I don't know where you got the 135v rating, but forget it.

It's a 3 watt 2700 ohm resistor, and will dissipate 3 watts when the voltage is 90 volts DC. (P = (V^2)/R). So, if the specified wattage rating is 3 watts, the circuit was designed to apply less than 90 volts to that resistor. Of course, a circuit fault might put more voltage across a resistor than intended, and that would have to be fixed, and the resistor would indicate that by overheating and smoking.

Edit: resistor voltage ratings are usually for momentary voltage that might cause the resistor to arc over. Typical max voltage rating for discrete resistors might be 200-600 volts, but as you see, for DC, the wattage rating may be exceeded long before the voltage is. AC or pulse current will be different, as r.m.s. current determines the power while the peak voltage determines whether the voltage rating is exceeded.

I don't know where you got the 135v rating, but forget it.

It's a 3 watt 2700 ohm resistor, and will dissipate 3 watts when the voltage is 90 volts DC. (P = (V^2)/R). So, if the specified wattage rating is 3 watts, the circuit was designed to apply less than 90 volts to that resistor. Of course, a circuit fault might put more voltage across a resistor than intended, and that would have to be fixed, and the resistor would indicate that by overheating and smoking.

Edit: resistor voltage ratings are usually for momentary voltage that might cause the resistor to arc over. Typical max voltage rating for discrete resistors might be 200-600 volts, but as you see, for DC, the wattage rating may be exceeded long before the voltage is. AC or pulse current will be different, as r.m.s. current determines the power while the peak voltage determines whether the voltage rating is exceeded.
The voltage rating was listed on the mouser site where I got it and this voltage is 275 dc from the power supply so I just want to make sure because these resistors get hot but it is 3 watt same as what was in there. And it’s a wire wound. These resistors are small bearly half inch.

Was the original wirewound?
Can you post a link to the mouser page?

the resistor types I mentioned a few weeks back were 750v type metal film ones.

https://www.mouser.com/ProductDetail/Vishay-BC-Components/PR03000202701JAC00?qs=LCMWAU1DZcx07iWwtn4Z2Q%3D%3D

perfect for this situation. :O

which DID you order?

Well it turns out that I never used that site before so the 6.8 and 8.2 were metal film and the oxide the 2.7 is a wire wound.

Was the original wirewound?
Can you post a link to the mouser page?

All the power resistors were wire wound.

Here’s the 2.7 3 watt wire wound

please post info links of the Mouser parts that were ordered, you should have gotten this info in a confirmation e-mail when the order was placed.
:yes:

Here’s the resistors I got

The only one in doubt is indeed the wire wond one.
https://www.mouser.com/ProductDetail/Vishay-BC-Components/PR03000206801JAC00?qs=LCMWAU1DZcwK0C0BKWoLFQ%3D%3D
https://www.mouser.com/ProductDetail/YAGEO/RSF200JB-73-680K?qs=oypCK0zG327iMn1SlkNR2g%3D%3D
https://www.mouser.com/ProductDetail/KOA-Speer/MOS3CT631R822J?qs=wxTalxQfganJz9Mm2017zw%3D%3D
https://www.mouser.com/ProductDetail/Ohmite/23J2K7E?qs=109ApXgPLfl02XFaCwg9Xg%3D%3D


The 750v ones I had shown on page 46 were a good match and even cheaper, :/

https://www.mouser.com/ProductDetail/Vishay-BC-Components/PR03000202701JAC00?qs=LCMWAU1DZcx07iWwtn4Z2Q%3D%3D

As a general rule, I try to get a voltage rating that is 2x above the circuit the resistor is to go in, not that a lower won't work, it's just for better longevity.

So the 2.7 k will work but may not last.

It's not going to immediately explode, throwing fire and sparks all over, it will work, but it will always be a weak point, prone to fail at some point.

I don’t understand what’s going on with this set anymore I put the other 2 resistors in v2 the image is even better but the b+ voltages are dipping again and maybe at this point if the voltages were up where they should be I might have video now. One moment there good the next they drop. I’ll have to change the 2.7k resistors maybe v1 v2 are drawing to much because they are not conducting at full. Who knows.

You guys need to read the datasheet a little more closely and take a step back.
The limiting factor on the resistor is power dissipation. Nothing to do with voltage rating.
https://www.mouser.com/datasheet/2/303/res_20-2758246.pdf

If you had 750 volts across a 2.7K resistor, it would be pumping out over 200W!

Old TV Nut had it right, you hit the 3W mark at 90 volts so there better be much less than that across the resistor.

You guys need to read the datasheet a little more closely and take a step back.
The limiting factor on the resistor is power dissipation. Nothing to do with voltage rating.
https://www.mouser.com/datasheet/2/303/res_20-2758246.pdf

If you had 750 volts across a 2.7K resistor, it would be pumping out over 200W!

Old TV Nut had it right, you hit the 3W mark at 90 volts so there better be much less than that across the resistor.

It's not more concerned 750 "across" the resistor itself, but more the being at that potential as a whole, and the possibility of there to be a breech of the outer layer if the voltage rating is to high.

The resistors he ordered are fine.

Breach of the outer layer to what? The 750 for the Vishay is across the resistor and subject to the same power limits.

Generally speaking for all resistors. 1W can handle 350 volts, 2W, 500 volts, 3W, 750 volts across the resistor. Constrained by power disippation and ambient temperature etc.

As for diodes I can’t see putting higher amp diodes in only to feed a draw and that’s not fixing a problem the output diode is way to hot it is definitely not normal I can’t even touch it it’s that hot and I tried the cheapy diodes and the output still gets hot. It appears that when working all the controls are working color controls vertical I have to find out why they are hot as it may answer why the video is not there yet.

As for diodes I can’t see putting higher amp diodes in only to feed a draw and that’s not fixing a problem the output diode is way to hot it is definitely not normal I can’t even touch it it’s that hot and I tried the cheapy diodes and the output still gets hot. It appears that when working all the controls are working color controls vertical I have to find out why they are hot as it may answer why the video is not there yet.

not really.

you have shown that you have good video with direct input, more than once I believe.

did you do a current test on this set now that you have a meter to do so?
was it more than 580-590ma?
if the original diodes are worn, it could explain them getting hot, and as mentioned before, the cheap ones are suspect as being counterfeit diodes, so they won't be much better, so putting in new 1a or 2a diodes should put the heating problem to rest.

Since you get good video from direct input, it is safe to say its not related to the power supply.

not really.

you have shown that you have good video with direct input, more than once I believe.

did you do a current test on this set now that you have a meter to do so?
was it more than 580-590ma?
if the original diodes are worn, it could explain them getting hot, and as mentioned before, the cheap ones are suspect as being counterfeit diodes, so they won't be much better, so putting in new 1a or 2a diodes should put the heating problem to rest.

Since you get good video from direct input, it is safe to say its not related to the power supply.
I did do the ma test and it was 550ma so that would suggest there’s no short I have these big diodes but don’t know the rating. And again after the set is on 10 or so minutes the voltage comes up within 5-7 volts normal voltage so now all the resistors are in v1 v2 and this video is so close. I noticed that the video would flicker on the screen as perfectly clear video so something is upsetting the video path.

"So if this is only drawing 550ma then the diodes should not be getting hot not warm but hot. Another mystery."

This is within the norm range.

These diode are 57 years old after all, and after getting hammered each and every time the set is turned on and the caps charge up, it would not be any surprise that a pair on new ones would help quite a bit, and the price dif between 1a & 2a is almost nothing.

"So if this is only drawing 550ma then the diodes should not be getting hot not warm but hot. Another mystery."

This is within the norm range.

These diode are 57 years old after all, and after getting hammered each and every time the set is turned on and the caps charge up, it would not be any surprise that a pair on new ones would help quite a bit, and the price dif between 1a & 2a is almost nothing.

Yes that’s true I will have to end up changing them if I could only get video it is so close I could taste it there is a coil right at the antenna input maybe someone turned it so I’m going to turn in and out carefully watching exactly how many turns if no better I’ll put it back exactly where it was because it almost seems like a very weak input signal. Nothing to lose at this point.

Are c1, c2 and c3 staying cool? :scratch2:

jr

Are c1, c2 and c3 staying cool? :scratch2:

jr

Yes but one is in the area of the 550ohm resistor it gets hot in that corner.

one you may want to try is listed on page 6 on the sams, step 5, coil A13, it is a visual only adjustment.

Yes but one is in the area of the 550ohm resistor it gets hot in that corner.

the 20w 550 gets hot enough to cook a steak in a decent amount of time! :D:yes:

That’s the last coil in the IF I already tried that one turns in and out little if any difference put it back exactly where it was that’s the coil with the diode video detect.

I’m almost burned out with this set although i don’t give up easily but trying that coil no difference from befor just alittle but I put it back. I’m wondering about the .001 caps in L4 and L5 to be honest I already did the leakage test with the .1 cap to ground and the cap dropped to 0 so I guess this means they’re good.

One thing to try is an AGC override, as shown on page 6 on sams, this is easy and needs few items and clip leads. Shown below. If it helps get a tuned picture , it means AGC is the problem.

500k potentiometer, linear.
9 v battery.

Wire the battery to the outer lugs of the potentiometer.
Hook negative line to chassis, and wiper of potentiometer to test point A on chassis.
Start sweep from 0v and work up from there to see if it gets a reaction.

You know I had a small feeling that the agc may be the problem because the agc pot does absolutely nothing if the agc is maxed couldn’t it distort the video like this. What could cause the agc not work or have it maxed. Wouldn’t the agc affect the video input B.

Input at point B bypasses the tuner and IF sections, and thus leaves ACG redundant.

Thus the point if you can't get it to work, you can always build a simple video amp to get the contrast levels right and go that route.

https://www.electronicsforu.com/electronics-projects/simple-video-amplifier

That’s another thing with the little video I have the contrast bearly makes a difference is this because of possible agc problems. And of course don’t have a 500k pot I think I have a 700 don’t know if this would work.

if its 700k then it should be OK,, anything above 100k should work, i picked 500k, cause they were most common.

700 OHMs, may load the battery down a bit however, not sure.

There’s not much to this agc the 50k pot and a 33k and 47k the pot checked good so this pot adjusts the bias on pin 6 of the 6hs8 correct?? I redone the k1 and it’s in this time I got a 680k rather then 680 ohm.

https://www.amazon.com/RadioShack-100K-Ohm-Audio-Taper-Potentiometer/dp/B007Z864ZU/ref=sr_1_6?crid=38PB7PRUX2FNS&keywords=potentiometer&qid=1666652324&qu=eyJxc2MiOiI1LjU0IiwicXNhIjoiNS4yMyIsInFzcCI6IjU uMDAifQ%3D%3D&sprefix=potentiometer+%2Caps%2C242&sr=8-6


It's audio taper, but should still work for the AGC bypass test.

Pics from today does this look like the agc maxed.

It's most likely 1 of 3 things.

A) the IF is so out of alignment that you cant tune in anything.

B) AGC is messed up and you can't tune in anything.

C) combo of both.

applying bias to the AGC test point will rule out one of these.

What if there is a higher voltage at the test point holding the tube at full agc then the test won’t work using a 9 volt battery how would this setup lower higher voltage if that works that way. Or does it maybe need a certain amount of voltage like the battery to turn it off per say. I do know that test point has 7.5volts there.

If you look at the “alignment instructions” in the sams, it says to connect a variable bias supply to point A, this will override any voltage present and allow you to set your own due the the high resistance of the the source.
Using a potentiometer and a 9v as described, should allow you to set the test point from 0 to 9v, which should be enough to see if AGC is the fault.

Ok well I’ll put that together and try and from what I have read agc is really not needed anymore since we are not using antenna anymore but rather stable inputs like cable.

This would be correct if the circuit were working as intended, but it may also so out of wack that it won't let you tune in anything.

The intent of doing this bias sweep on point A is to see if it has any effect at all on the screen, better / worse.
If there is a noted change, then it prob is AGC related, if not, then it's IF and alignment.

I’m going to go over a few resistors in the agc circuit then on to the 9v get up.

Just for the heck of it chassis back on back but upon plugging it in have a test lead on v1 with antenna and just as the hv came up it jumped 4kv and when it did the voltages on v1 and 2 neared 100 v then hv dropped again did this twice this just about confirms something is getting in or shorting intermittently somewhere. I never seen this since working on this chassis.

Well it’s official the 9v setup proves an agc problem voltage jumps up 11 volts on v1 and that’s a huge difference using the only pot which was 900k

Just for the heck of it chassis back on back but upon plugging it in have a test lead on v1 with antenna and just as the hv came up it jumped 4kv and when it did the voltages on v1 and 2 neared 100 v then hv dropped again did this twice this just about confirms something is getting in or shorting intermittently somewhere. I never seen this since working on this chassis.

The voltages when it first comes on really don't mean that much, it's once it is all warmed up and stable that matters.

There is a reason for doing the AGC bias test, this goes back to 2016 when I was working on my CTC-16XL and it too had IF problems, and old_tv_nut said the following..
---
The AGC circuit is a feedback circuit. This means that the 9 volts at the plate does not necessarily mean anything is wrong with the AGC circuit itself. It may be getting an incorrect detected video signal at the grid due to some other reason (like a dead IF) and trying to correct it by changing the AGC voltage. You need to check the detected video for starters. If it's missing, check and/or replace the AGC tube. And, you may be right that some component is bad. Check all the voltages in this area. Check resistor values wherever voltages are way off. Further trouble shooting could involve breaking the feedback loop by connecting an adjustable bias to the AGC line, as you would for aligning the IF. If video is missing or wrong amplitude and you can't get it by manually setting AGC bias, there is something dead in the IF or tuner.
---
so please try that bias override, and see the results.

The voltages when it first comes on really don't mean that much, it's once it is all warmed up and stable that matters.

There is a reason for doing the AGC bias test, this goes back to 2016 when I was working on my CTC-16XL and it too had IF problems, and old_tv_nut said the following..
---
The AGC circuit is a feedback circuit. This means that the 9 volts at the plate does not necessarily mean anything is wrong with the AGC circuit itself. It may be getting an incorrect detected video signal at the grid due to some other reason (like a dead IF) and trying to correct it by changing the AGC voltage. You need to check the detected video for starters. If it's missing, check and/or replace the AGC tube. And, you may be right that some component is bad. Check all the voltages in this area. Check resistor values wherever voltages are way off. Further trouble shooting could involve breaking the feedback loop by connecting an adjustable bias to the AGC line, as you would for aligning the IF. If video is missing or wrong amplitude and you can't get it by manually setting AGC bias, there is something dead in the IF or tuner.
---
so please try that bias override, and see the results.

So I assume the voltages at the agc tube 6sh8
3 7.95v 9 32.53 6 116 7 83. Doing the 9v setup then check voltages?

This should be done with the crt hooked up and a signal being fed in the tuner, adjusting the AGC bias to see if it makes any marked improvement in the picture on screen.

This should be done with the crt hooked up and a signal being fed in the tuner, adjusting the AGC bias to see if it makes any marked improvement in the picture on screen.

Ok let’s say it makes a huge difference nice picture what would be the next step because I’m lost at this point I have checked all the resistors in and around the tubes associated with the agc so if this proves to give a great clear picture what’s next.

If it does turn out to be an AGC related issue, the whole AGC / NOISE GATE system will have to be taken into account, as Old TV Nut pointed out, this is a feedback system, involving not just the 6HS8 immediate area, the whole point of this is to find if there is or is not a problem in this circuit.

if there is not, then on to the IF.

Well unfortunately the bias test did nothing I even jumped the pot and gave it 9 v no change. This is beginning to really hurt. So I guess the agc is trying to fix or adjust the input.

Since you have given test point A a bias sweep of 0-9v with no results, and been over the resistors in the IF section more than once from what I can see, this basically only leaves one thing left, the IF is badly out of alignment, this is likely causing AGC to overcompensate, as there is no video for it to reference to, causing the abnormal voltages.

Who knows, the de-tuned state may also disrupt the normal voltages, be that as it may, color sets are quite hard to align even for the most experienced techs with the right equipment on hand.

It took me 3 tries to align my BW Arvin set (45mhz), and that was just with a frequency generator and a volt meter.
But for color, you need a sweep marker generator and a oscilloscope plus lots of know-how.

But the one thing that must never be done is, try to visually align a color set's IF, this will always end badly and make is worse than when sttarted.

While I can understand the IF but what happened here today I still think there is something shorted possibly to ground maybe a cap that I didn’t change yet there are caps still in there originals because on the bench the hv jumped instantly as if there was an arc and at the same time the voltages jumped up on the IF but it was instant a bad alignment would not do this hv jumped 4kv and the IF 15v so I’m going to hope to find this it could be anywhere and besides the picture has flickered in clear on it own several times already so I don’t think the IF is out. I have no idea how I’m going to find this because other then the agc pot not working probably because it’s maxed already trying to fix the signal all other controls work even though something could be leaking somewhere or to ground. I’m sure it wouldn’t take much to corrupt the video signal. So bottom line is voltage still dips diode gets hot so something is not right. I have 2 4 amp diodes I tried they only get warm so it’s not a diode. To bad this forum dont have audio easier to talk then type.

For that I still suggest a longevity test, remove V1,V2,V3, hook direct video to point B as before, heck, hook audio input to pin 3 of the still connected volume control plug connector to R1 if ya want, you should get some sound, run video for 30 min ( do NOT leave it unwatched ).
If OK, try another 30, try longer, and so on.

For that I still suggest a longevity test, remove V1,V2,V3, hook direct video to point B as before, heck, hook audio input to pin 3 of the still connected volume control plug connector to R1 if ya want, you should get some sound, run video for 30 min ( do NOT leave it unwatched ).
If OK, try another 30, try longer, and so on.

Ok but what am I accomplishing I already have good video at test point B and my goal is to have it work with its own tuner I know you said I could take the other route with video inputs but I would rather find this headache and be done with it. After seeing the video flicker in and out clear there is another obvious problem something is more then likely leaking to ground I feel it don’t know why but I do. And an arc somewhere can only do what it did in an instant I don’t think it’s a tube. I had an rca don’t remember what chassis but I had a disc cap short dead to ground and took out the flyback and ho transistor so those caps do go bad. In this case I just don’t know.

What I did try was disconnected both diodes and ran the heaters and checked the positive side of the power supply caps and I got a very low voltage reading on the 250v 260uf string and also the 450v 80uf but all the other caps were zero so I pulled each tube one by one thinking heater cathode short but still had that small reading. These caps do go to ground but still why only these caps.

The point is to eliminate any possible problems from the video det forward first, then work back.
If you can determine that you can run the set for extended periods of time with A/V input without any strange things popping up, then you can turn attention on IF/ tuner.

But if things still act strange with A/V input when run for long periods, address that first.

Well the sound does fade on and off but that’s probably because of the lousy video

What I did try was disconnected both diodes and ran the heaters and checked the positive side of the power supply caps and I got a very low voltage reading on the 250v 260uf string and also the 450v 80uf but all the other caps were zero so I pulled each tube one by one thinking heater cathode short but still had that small reading. These caps do go to ground but still why only these caps.

"disconnected both diodes "

but c151 was still there, right?
that gave some charge to C1, not much.

C1 & C2A = voltage doubler when added with the diodes, the other caps are filters.

C151and c152 are disc caps and both diodes completely disconnected there wouldn’t be anything flowing out of those caps from the heater string.

Ok but what am I accomplishing I already have good video at test point B and my goal is to have it work with its own tuner I know you said I could take the other route with video inputs but I would rather find this headache and be done with it. After seeing the video flicker in and out clear there is another obvious problem something is more then likely leaking to ground I feel it don’t know why but I do. And an arc somewhere can only do what it did in an instant I don’t think it’s a tube. I had an rca don’t remember what chassis but I had a disc cap short dead to ground and took out the flyback and ho transistor so those caps do go bad. In this case I just don’t know.

and about that, things of this era just do not compare to the SS one, as everything went solid state, it also went cheap cheap CHEAP, the components were just not built to the same standards, not expected to last, all disposable, hell, only a fraction of the CRTs from SS TVs even still worked after 10 years, let alone 30+!

All I know is there is something that I would call an arc because of how the hv changed and IF voltages in an instant and if the chassis was in at that moment the video probably would have been clear for that moment.

All I could do now is look at the old caps that are still in the chassis more so the ones that tie to ground along with all the rest of course they are old and should go and if there’s a bad one I will know it.

any leakage from heaters should have been AC, If it was DC, then it was most likely residual voltage from before.

Prob nothing.

I did get an ohms reading but I didn’t write it down.

Well how about this scenario being the hv jumped up and the voltages went up on the 2 IF I could possibly have a cap at the horizontal oscillator that may be defective and that would possibly change the frequency and there for mess up the agc and down to the IF strip. I never had a new bad or defective cap but I guess it’s possible.

I’m wondering why if v6 is pulled then there is no horizontal oscillator v12 it don’t run shouldn’t the oscillator run without v6. Maybe this is my problem if the oscillator should run by itself. I’m not sure looking at the block diagram if v6 is needed or not for the oscillator to run.

I'm rather unfamiliar with the way Zenith did their horizontal oscillator circuits, it's clear that this set has a clone of the Zenith and not RCA, or some other kind.

Very close to this.
https://www.earlytelevision.org/pdf/zenith_25mc30_sams_757-4.pdf

do remember , the horizontal oscillator is a phase locked loop, and where I'm not sure of all the aspects of how it's implemented in this set, but, removing V6 is most likely breaking the feedback chain, and the oscillator won't start w/o it.

Is there a reason why L42 gets really hot along with the focus coil L42 measures 35ohm so far it’s still good but why both really hot these 2 tie into the agc and noise gate kind of odd being the problems in the agc circuit. When I first got this set the 100k resistor on the focus coil was burned.

Well how about this scenario being the hv jumped up and the voltages went up on the 2 IF I could possibly have a cap at the horizontal oscillator that may be defective and that would possibly change the frequency and there for mess up the agc and down to the IF strip. I never had a new bad or defective cap but I guess it’s possible.

The horizontal running off frequency shouldn't effect AGC a noticable amount. If you have ever misadjusted the horizontal hold on a working set you'd see that the video amplitude stays very close to normal with the hold out of locking range....If the set by design lost IF signal because misadjusted hold screwed up AGC then the sets wouldn't be able to receive a signal unless the horizontal miraculously synced up to a station without signal....No maker would sell something so Mickey mouse.

Again, the whole point of applying the 0-9v sweep to the AGC test point was in hope that the circuit may have been malfunctioning, and by giving it external control power, it would have given the IF a chance to pass something through, but this did not help, again pointing at an alignment problem, and not related to any other areas.

EDIT==

EM addressed the resistor issue before...
"I think I have heard that if the coil is at it's extremes it will burn that 100K resistor."

But I have been looking for a draw down in voltage as a possible reason video is screwed up and this maybe it I don’t know but the focus coil and L42 get really hot L42 got so hot that the glue holding the coil in let loose and the coil fell out so I put hot glue and I just noticed the coil fell out again heating the hot glue. The resistance check on v6 and v12 were good so the focus coil and L42 both are tied to 2 locations in the agc feedback circuit the 2.2pf and the 470 pf disc caps c96 130pf is new so if the focus coil is bad or any one of the 2 caps along that line are bad then maybe this could solve it. Amazing but I found a new focus coil.

Any issues that may, or may not be with the focus coil area are not related to the tuning / IF or AGC issue, if it was, you would have seen a substantial change in video on screen when AGC test point A was given a bias sweep from 0 to 9v.

This means that no matter how AGC tries to set gain, no matter what the voltages are on V1 & V2, or the tuner, no video is going to get from the tuner to the detector diode w/o getting corrupted.
The alignment is wrong.

There are voltages between the 2.2 cap if this cap is bad then it would upset the sync sep and as been stated before is that if the sync sep is not right I won’t get video or be able to tune anything in. The voltage on pin 6 IIRC was low and should be 145v and the agc does nothing as it should change voltage via the agc pot. It’s just my thought I could be wrong.

I know I’m being stubborn but if the alignment was so far out then I would not have had the picture flicker in clear as can be for a second and I have 2 components getting very hot for a reason and need to find out why like the diode getting hot heat equals voltage so I need to find out why and if it corrects any other problems then that’s a plus.

What you may see in the first second or two is not relevant, as how any given receiver behaves before all the components come up to normal temperature and operating voltages is very different from up in a stable state.
Thus the alignment instructions clearly state “allow a 20 minute warm up period.”
What you are most likely seeing is the IF/and or tuner passing video before things have fully come up to power and stabilized, this is not unusual, the alignment method of course would be to get it to pass video when it's fully up and warm.

Also, the sync sep has been shown to be in a good state already, if it was not, you would have no video lock, and or unstable video with the direct video input.

What you may see in the first second or two is not relevant, as how any given receiver behaves before all the components come up to normal temperature and operating voltages is very different from up in a stable state.
Thus the alignment instructions clearly state “allow a 20 minute warm up period.”
What you are most likely seeing is the IF/and or tuner passing video before things have fully come up to power and stabilized, this is not unusual, the alignment method of course would be to get it to pass video when it's fully up and warm.

Also, the sync sep has been shown to be in a good state already, if it was not, you would have no video lock, and or unstable video with the direct video input.
Ok true but I still have the focus coil and the peaking coil very hot this is not right for only a minute on the focus coil could be shorted but I didn’t check it yet.

Pardon my ignorance, but what is the "focus coil" on the schematic? This set uses electrostatic focus.
Ah, nevermind - L49 - focus coil.

I still have pin 8 of v1 that the chart says 3.2k but I’m still getting 6.2k after changing the resistors so that’s a problem unless the chart has a typo. I have a Motorola book for different chassis and there is a 907-B I don’t know if mine is a B but if I take the 8.2 off ground then pin 8 shows the correct resistance maybe the 907-B is updated it’s from 1969.

I have to look into the video detect diode the one I put in may not have been good so can I mount this diode on the outside run 2 small wires to an opening on the chassis and mount it to a small tie strip for easy access to try different diodes. Maybe this diode has excessive leakage and it’s tough to reach it every time.

I have to look into the video detect diode the one I put in may not have been good so can I mount this diode on the outside run 2 small wires to an opening on the chassis and mount it to a small tie strip for easy access to try different diodes. Maybe this diode has excessive leakage and it’s tough to reach it every time.

Altering the detector like that may result in unwanted undesired results.

How does one know if the diode has excessive leakage. Like many other things that test good but really is bad like tube testers.

The diode test with any DVM is good enough in this situation to detect any faulty diodes.
The detector is not under any high power load or voltage extremes.

The diode test with any DVM is good enough in this situation to detect any faulty diodes.
The detector is not under any high power load or voltage extremes.

Well it does check good but at this point I’ll check anything to rule out.

Still didn’t come up with the reason why pin 8 v1 is at around 6.3k when it’s supposed to be 3.2k. I’m letting everything else go for now and have to focus on this discrepancy with pin 8 v1. I don’t even know if sams is wrong because pin 8 v2 is 6.4k and matches sams.

More likely than not, the data on the SAMs is in error, and 6.3k is correct.
You should really look into what Squirrel Boy mentioned, and try injecting IF signals into the string at the various stages via the grids of the tubes, (pin 2), using a decoupling capacitor to protect the tuner subber from any voltage that may be on the grid.

Since you can't place the chassis in service position for this, or have a tube test socket, you will have to get something like some 30 Gauge Wire Wrap Wire, and wrap a few turns around P2 of the tube of the stage under test, as this has to be done with it hooked up fully to the CRT to see if you get a picture.

More likely than not, the data on the SAMs is in error, and 6.3k is correct.
You should really look into what Squirrel Boy mentioned, and try injecting IF signals into the string at the various stages via the grids of the tubes, (pin 2), using a decoupling capacitor to protect the tuner subber from any voltage that may be on the grid.

Since you can't place the chassis in service position for this, or have a tube test socket, you will have to get something like some 30 Gauge Wire Wrap Wire, and wrap a few turns around P2 of the tube of the stage under test, as this has to be done with it hooked up fully to the CRT to see if you get a picture.

+1 basically your using your tuner subber like a B&K analyst's IF output....Only I'm not sure why you bought the subber instead of an analyst in the first place....I never use my tuner subber, but I use my analyst more than my scope (it's probably second to my DMM interms of use).

More likely than not, the data on the SAMs is in error, and 6.3k is correct.
You should really look into what Squirrel Boy mentioned, and try injecting IF signals into the string at the various stages via the grids of the tubes, (pin 2), using a decoupling capacitor to protect the tuner subber from any voltage that may be on the grid.

Since you can't place the chassis in service position for this, or have a tube test socket, you will have to get something like some 30 Gauge Wire Wrap Wire, and wrap a few turns around P2 of the tube of the stage under test, as this has to be done with it hooked up fully to the CRT to see if you get a picture.

So your saying inject signals from the subber to pin 2 of the first 2 IF tubes. Ok well that’s next. .01 cap or .1 I’ll leave the rf plug from the tuner out while trying each tube.

Ok v1 same v2 was impressive v3 nothing so either L4 was turned or something right there at v1 is the problem or just befor it I don’t know. The picture is from v2.

This is a 1st IF problem, something between L3 and L4.

First replace
R36,R37,R38,R42,R43,R44,R45 with all new carbon film parts, do not rely on any meter to tell you the old parts are OK, at this point, you want all new resistors in there, of coarse, paying close attention to lead dress and placement when put in, making it look as close to original as you can, then go on from there.

This obviously means all is good from the 2nd IF onward, including the detector diode! :banana::D

Well this somewhat proves it don’t need a full blown alignment.

there is a problem in the first half.

Ok v1 same v2 was impressive v3 nothing so either L4 was turned or something right there at v1 is the problem or just befor it I don’t know. The picture is from v2.

This is very good looking. Looks like you now have a light weight less expensive
B&K Analyst....

http://videokarma.org/attachment.php?attachmentid=204990&d=1666899517

If you apply that signal to the plate of V1 with the coupling capacitor in place
you might be able to pass the signal through the IF Coil A6, it should be tuned
to that IF frequency and pass the signal. Not sure of any other way to be sure
that coil is actually "Good" as far as passing the signal, Even though the ohms
might read ok.....
Other than that, you will have to go through all those parts around V1 to find
the problem.....

Anyway, looks better than I expected. I'm not sure, but it even looks like
that girl may even have red lipstick on, or it's just my wishful thinking....
If there is - well then it's tuned well enough to pass burst signal too....
I would not turn anything till you can get this set working from it's own tuner.....


You know.... I wonder if you took the iF plug from this tv's own tuner, and jumped
it ahead with a coupling cap, to that V2, if you would see the same results....?

It would also rule out the tv's own tuner as a source for trouble......

You guys have done some good work here......


.

This is very good looking. Looks like you now have a light weight less expensive
B&K Analyst....

http://videokarma.org/attachment.php?attachmentid=204990&d=1666899517

If you apply that signal to the plate of V1 with the coupling capacitor in place
you might be able to pass the signal through the IF Coil A6, it should be tuned
to that IF frequency and pass the signal. Not sure of any other way to be sure
that coil is actually "Good" as far as passing the signal, Even though the ohms
might read ok.....
Other than that, you will have to go through all those parts around V1 to find
the problem.....

Anyway, looks better than I expected. I'm not sure, but it even looks like
that girl may even have red lipstick on, or it's just my wishful thinking....
If there is - well then it's tuned well enough to pass burst signal too....
I would not turn anything till you can get this set working from it's own tuner.....


You know.... I wonder if you took the iF plug from this tv's own tuner, and jumped
it ahead with a coupling cap, to that V2, if you would see the same results....?

It would also rule out the tv's own tuner as a source for trouble......

You guys have done some good work here......


.
Well now I’m going to go over all resistors at v1 and I’m sure the sets own tuner is good because I get the same result from the subber and the tv tuner I don’t know how far off resistors in the IF strip have to be before knocking out the rf signal. I’m sure that coil at v1 is good the wire inside is heavy gauge wire but anything is possible I did measure it and it’s under 1 ohm. And this v1 is the one that sams indicates that pin 8 should be 3.2k but it actually measures 6.3k so I hope it’s a sams typo because there is no reason that I can find why this would be.

Again it will be most advantageous for you to replace the resistors previously mentioned with new 2% or better, as the first half of the IF can't pass a signal.
The cost of doing this will be very low and the gain will be high, don't just rely on DVM testing, the original ones are old and you know there is a fault in this area, so go ahead and replace.

Problem areas include.

L1 47.25MHZ TRAP
L2 39.75MHZ TRAP
L3 1ST Video IF
perhaps
L4 2nd Video IF
As you could feed a signal direct into V2, but not any steps before it.
again, replacing said said resistors could improve thing quite a bit.

Good Morning:

You know, you could possibly try disconnecting pin 2 of L3, A7, same coil, and feeding
that tuner subber signal to G1 of V1, to see if possibly that trap circuitry is killing
your IF signal..... Just be sure your V1 voltages don't change, like possibly G1
changing bias or something...
You might even check that R23 the wiper arm does not leak to ground, or any
other pin for that matter..... You might even try disconnecting that wiper
arm from the L3 coil and see if it passes a signal.......


.

After all that changing all those resistors the pic shows little to no change and the voltage is 97volts on pin 8 so that’s good. When I had the 10k and 2.2k off I checked L3 under 1 ohm. The other L1 L2 are good also.

This is it. Trying to send a pic but won’t go. But it’s the same. Back to square one. I also checked L4 and it matches L5. I wonder if the agc is messing with the signal the video from antenna input in v2 would the agc have affected that because it didn’t or is agc only at v1.

You say voltage is up on pin 8, this is progress, but you still have to isolate the fault, and that will take a few steps, of chassis in/out going by what Squirrel boy suggested.

==
Try disconnecting pin 2 of L3, A7, same coil, and feeding
that tuner subber signal to G1 of V1, to see if possibly that trap circuitry is killing
your IF signal..... Just be sure your V1 voltages don't change, like possibly G1
changing bias or something...
==
If you get a picture when you do this, then L1,L2,L3 are out of tune, if you do not, and still no video when trying to feed to pin 2 of V1 (which should be 3-7v depending an AGC, ) then L4 is likely out of tune.

You say voltage is up on pin 8, this is progress, but you still have to isolate the fault, and that will take a few steps, of chassis in/out going by what Squirrel boy suggested.

==
Try disconnecting pin 2 of L3, A7, same coil, and feeding
that tuner subber signal to G1 of V1, to see if possibly that trap circuitry is killing
your IF signal..... Just be sure your V1 voltages don't change, like possibly G1
changing bias or something...
==
If you get a picture when you do this, then L1,L2,L3 are out of tune, if you do not, and still no video when trying to feed to pin 2 of V1 (which should be 3-7v depending an AGC, ) then L4 is likely out of tune.
I have the bottom off the set and turned on it’s side so I don’t have to take it out again. I remember there was 7.5v on pin 2 and I don’t remember if it changed at all with turning the agc.

7.5v on the grid should be OK for V1 to work, if it does, the gain level needed will be much less than was for V2.

Not really ... its square 5001.
Try these: Feed (as usual through a .01 or .001 uF cap) the external tuner to
pin 2 of V2. Does it work?

Remove V1 and repeat ... is there any difference?

Try connecting the input through the usual cap to the pin 7 on the v1 socket ...
does it work?

Connect the input to pin 2of v1. Check the voltage to ground at the cap lead.
(With tube out). Insert v1. Does the voltage change at all? Does it work?
Wiggle v1 vigorously ... does anything change. Try a different 6EH7 ... does anything change, with wiggling.
If its close quarters, attach a thin bent wire to the probe tip to reach the pins.

Disconnect the wire to pin 2 of L3, everything else the same. Does it work? Is the voltage at pin 2 of v1 the same? Check voltages at each and every terminal of
L1, L2, and L3 ... all should be the same. This takes a high impedance voltmeter.
IF there is any picture at all ... does it change differently as you touch different terminals.

Finally ... have you checked that each and every pin of v1 is in fact making
a connection to a wire connected to that pin? By that, I mean actually touching
a probe to the pin itself, with the tube pulled a little out so you can reach the pin ...
and wiggle the tube. Of course, a tube extender is better.

Not really ... its square 5001.
Try these: Feed (as usual through a .01 or .001 uF cap) the external tuner to
pin 2 of V2. Does it work?

Remove V1 and repeat ... is there any difference?

Try connecting the input through the usual cap to the pin 7 on the v1 socket ...
does it work?

Connect the input to pin 2of v1. Check the voltage to ground at the cap lead.
(With tube out). Insert v1. Does the voltage change at all? Does it work?
Wiggle v1 vigorously ... does anything change. Try a different 6EH7 ... does anything change, with wiggling.
If its close quarters, attach a thin bent wire to the probe tip to reach the pins.

Disconnect the wire to pin 2 of L3, everything else the same. Does it work? Is the voltage at pin 2 of v1 the same? Check voltages at each and every terminal of
L1, L2, and L3 ... all should be the same. This takes a high impedance voltmeter.
IF there is any picture at all ... does it change differently as you touch different terminals.

Finally ... have you checked that each and every pin of v1 is in fact making
a connection to a wire connected to that pin? By that, I mean actually touching
a probe to the pin itself, with the tube pulled a little out so you can reach the pin ...
and wiggle the tube. Of course, a tube extender is better.

The picture posted yesterday was when fed into the grid of V2, but there was nothing when he tried the same on V1, he has not tried the plate of V1, however, but he is going to try again with the grid of V1 unhooked from L1,L2,L3, But I suspect the problem is L4 :(

I don’t know there’s something else wrong here L42 keeps getting so hot it’s falling out of the holder that it’s in this is definitely not right the wire on this coil is like hair and if it breaks I’ll have even more headaches unless I find out why.

Maybe there’s something going on with k1 that I made all resistances seem to check out ok but I’ll probably put the original k1 back in because the k1 is agc and tied to all of this madness.

Maybe there’s something going on with k1 that I made all resistances seem to check out ok but I’ll probably put the original k1 back in because the k1 is agc and tied to all of this madness.

the hot coil problem is most likely due to a faulty C96, But you can't get the exact replacement for it, it may even be what burned r145.

it can be replaced with 2 caps in series,
https://www.mouser.com/ProductDetail/TDK/CC45SL3FD221JYGNA?qs=eSfX1CQlHqregLrjw6zMJw%3D%3D
https://www.mouser.com/ProductDetail/TDK/CK45-B3FD331KYNNA?qs=2FIyTMJ0hNmlhSEPCXzdjw%3D%3D

this is unrelated to K1
2 3kv caps in series that = 6kv@132pf total

get 2 new 1000v 2amp power diodes at the same time.

C96 is a 130 6kv it’s new I still have the old one. Yet in the pic the other day the focus was good unless this cap is leaking I don’t know. I was able to get a new one from moyers.

the hot coil problem is most likely due to a faulty C96, But you can't get the exact replacement for it, it may even be what burned r145.

it can be replaced with 2 caps in series,
https://www.mouser.com/ProductDetail/TDK/CC45SL3FD221JYGNA?qs=eSfX1CQlHqregLrjw6zMJw%3D%3D
https://www.mouser.com/ProductDetail/TDK/CK45-B3FD331KYNNA?qs=2FIyTMJ0hNmlhSEPCXzdjw%3D%3D

this is unrelated to K1
2 3kv caps in series that = 6kv@132pf total

get 2 new 1000v 2amp power diodes at the same time.


Not really square 1, or square 5001. You are making progress......


I was just looking at the schematic & thinking about the hot focus coil too....
But I was wondering about the other part of the circuit....... You know, the
part over by V1 where there has to be a rotten nut.....

I'm wondering about C60, & R87, & R14. At this point any Variable Resistors
should be checked from all 3 pins to ground for a possible internal short, not
just checking to be sure they read their rated resistance.... I still did not see
a post about R23 to be sure there is no short to ground from any of it's pins...
Think about that "tin wiskers" stuff inside these pots.....

Any way poor Timmy being pulled in 30 different directions to check this, and
replace that..... I think he needs a beer....... And if he ain't drinking yet
well then he's a strong determined individual!

The other bad bunch-a nuts can be hiding in that V6 area, where this focus
pulse is going - See that pin 3 with 2.5V on it, and with the scope pic of that
450V P-P wave.... No way you going to be able to figure out what should
really be there..... And that little circuit helps that K1 do it's thing, and it's
attached to V1, or did I say that once already.....


.

unless there is some other weird error in the way the flyback was wired back up, I'm not sure what is going on here.

Not really square 1, or square 5001. You are making progress......


I was just looking at the schematic & thinking about the hot focus coil too....
But I was wondering about the other part of the circuit....... You know, the
part over by V1 where there has to be a rotten nut.....

I'm wondering about C60, & R87, & R14. At this point any Variable Resistors
should be checked from all 3 pins to ground for a possible internal short, not
just checking to be sure they read their rated resistance.... I still did not see
a post about R23 to be sure there is no short to ground from any of it's pins...
Think about that "tin wiskers" stuff inside these pots.....

Any way poor Timmy being pulled in 30 different directions to check this, and
replace that..... I think he needs a beer....... And if he ain't drinking yet
well then he's a strong determined individual!

The other bad bunch-a nuts can be hiding in that V6 area, where this focus
pulse is going - See that pin 3 with 2.5V on it, and with the scope pic of that
450V P-P wave.... No way you going to be able to figure out what should
really be there..... And that little circuit helps that K1 do it's thing, and it's
attached to V1, or did I say that once already.....


.

The agc pot checked already for anything and r23 didn’t check yet but the 2.2pf+25 cap I actually have one coming. And yes I know the agc network is hooked to v1 so with L42 and focus coil getting hot there’s the 2.2pf cap and the 130pf hopefully one of these is the cause.

unless there is some other weird error in the way the flyback was wired back up, I'm not sure what is going on here.

Flyback is good I went over that.

I would also think that C59 would be suspect, its getting hammered with pulses from the flyback.

DANG this set is REALLY an oddball one!
:scratch2:

I still have the original 130pf 6kv and I have a 470pf 2kv and I have a 2.2Pf +25 pf 1kv coming sams don’t show a voltage for the 2.2pf I hope this cures L42 from getting hot that is very delicate.

Disconnecting the 470pf and 2.2pf made no difference L42 still getting hot and made no difference with video the 22ohm on v1 was 28+ohms so I changed the 22ohm on v2 it was 26+ohms on since doing this I don’t have the good video I had on pin 2 of v2. The batteries are at 8v maybe the subber is not working at full because of that. As for L42 all I got left is the focus coil or the 130pf 6kv cap which is new so I don’t know what’s more likely.

Has that big dropping resistor network been changed? r142-144?

Has that big dropping resistor network been changed? r142-144?

Are you referring to k1 ?

I did not think that those caps in the sync/ AGC area had anything to do with the L42 heating problem, you unhooking them just confirmed that, the way they are doing things in this set is confusing to say the least, BUT, the current path for L42 has to be between pin 1 of the flyback and pin 8, and also the resistor network to ground.
But what is really going on here is odd.

Are you referring to k1 ?

i mean the 3 big 22 meg 2 watt resistors in the focus circuit

i mean the 3 big 22 meg 2 watt resistors in the focus circuit
Yes they are new along with the 130 cap

So I could have probably used the one single 66 meg focus resistor that’s used in the ctc series clone chassis and rca.

So I could have probably used the one single 66 meg focus resistor that’s used in the ctc series clone chassis and rca.

yes, they are sill to be found all over the place.

yes, they are sill to be found all over the place.

But can that single 66 meg be used in place of 3 22 meg resistors. Why Motorola used 3 resistors when they could have used one. I have a bunch of those resistors.

But can that single 66 meg be used in place of 3 22 meg resistors. Why Motorola used 3 resistors when they could have used one. I have a bunch of those resistors.

yes, the big 66 HV ones are much better in this case than small ones cause they were made just for such this task, and multi small ones have to be rated 2kv each or higher, its much easier to get a big 66 meg 6kv one, as they are all over the place.

yes, the big 66 HV ones are much better in this case than small ones cause they were made just for such this task, and multi small ones have to be rated 2kv each or higher, its much easier to get a big 66 meg 6kv one, as they are all over the place.

When I changed those 3 22meg resistors I just got 22meg 2 watt resistors I didn’t specify 2kv rating does those pose a problem of any kind. ??

When I changed those 3 22meg resistors I just got 22meg 2 watt resistors I didn’t specify 2kv rating does those pose a problem of any kind. ??

It stands to reason that they should be, you have 4-6kv on one side, ground on the other.

they may have used the 3 22k ones for Creepage and clearance for high voltage reasons.

but at any rate if they are not rated for 2kv, they may be a source of trouble.

22meg @ 2w 2kv seems to be unobtainium, so you are better of with a big 66m 6kv one.

I’m going to put the single 66meg resistor in but if the resistors I had put in are just ordinary 22meg 2 watt resistors then is it safe to say they were passing excessive voltage to ground. After all there is 4-6 kv on them.

I dont get why sams don’t list certain resistors like the 3 in the focus circuit.

I’m going to put the single 66meg resistor in but if the resistors I had put in are just ordinary 22meg 2 watt resistors then is it safe to say they were passing excessive voltage to ground. After all there is 4-6 kv on them.

Reading that I don't think you understand how ohms law or resistor voltage ratings work. The same 6KV will be across those 3 resistors regardless of their voltage rating. Resistors don't pass voltage, they pass current and that too wouldn't necessarily change with voltage rating.

The voltage rating on the resistors is the maximum Voltage that you can put on the terminals and expect voltage to not cause arcing across the terminals....If it arcs it probably will do so noticably, and if it arcs it will pass current NOT voltage.

Tom: I don't believe that arcing across terminals is what really determines
voltage ratings of at least carbon composition and possibly metal film resistors.

The reasson is that for a given voltage rating, terminal strips of the same outer material of the same spacing have higher voltage ratings. For a given size (spacing) epoxy transistors and diodes have enormously higher ratings.

I suspect that for carbon composition reststors the voltage rating has to do with possible internal damage due perhaps to tracking. In any case, experience says that the actual usable voltage for one and two watt carbon composition resistors of high resistance starting about 1947 or 48 is enormously higher than the ratings. The two watt ones easily take 2 kV.

I've used 2 watt 1 meg carbon resistors pulsed to 2.5 kV run continuously for months and on and off for 20 years with zero failures. Ditto for 1/2 watt resistors at 1 kV. One circuit generates 20 kV pulses with 800 pS rise times using 22 series connected ordinary transistors (yes, all one type and all only two near-sequential batches from one manufacturer) in avalanche mode with the bases driven by pulse transformers with resistor bias networks. The pulse rate was up to 10 kHz. I was stupefied when the idea worked at all, but after 20 years with zero failures in numerous systems .....

They ran continuously to keep the temperature constant as they were driving crystal polarization rotators that needed to keep the resonant frequency constant to better than 0.5 ppm (and rotators, while being quartz just like radio crystals, are an abysmally bad temperature quality cut).

I figured Timmy was talking about modern carbon film resistors which probably are less resistant to arcing than the old carbon comps. I doubt he would be as likely to look up the voltage rating on a period part as he would a modern replacement being considered.

It makes sense the old carbon comps would have better resilience against over voltage since there's a nice straight path between the terminals unlike some of the film resistors now that have a spiral which can potentially arc between adjacent tracks and or the terminals.

Either way, there has to be SOMETHING causing the peaking coil L42 to get hot, and I had serious doubts that it had anything to do with the sync / AGC area (C59,C60), him unhooking them confirmed this, so it has to be something with the current path in the flyback transformer pins 1 & 5, which also includes the resistor net to ground off C96, there is no way to know if the 2w ones he put in there are not up to the job, but there is no way to know if they are as well, but if he does have a 66m 6k resistor that's made for just this situation, best to try it and see if it helps. :)

I figured Timmy was talking about modern carbon film resistors which probably are less resistant to arcing than the old carbon comps. I doubt he would be as likely to look up the voltage rating on a period part as he would a modern replacement being considered.

It makes sense the old carbon comps would have better resilience against over voltage since there's a nice straight path between the terminals unlike some of the film resistors now that have a spiral which can potentially arc between adjacent tracks and or the terminals.

Actually I was talking about the modern resistors not the old ones

Well the 66meg is in place and the L42 is still getting exceptionally hot all that’s left is maybe the focus coil or can the coil even cause this L42 to get hot I’m sure it gets warm under normal conditions but it’s way to hot.

does it still get hot with the 1V2 removed? :O

does it still get hot with the 1V2 removed? :O

I was going to say if the 1v2 is shorted which I doubt or the 130pf is shorted which is new cause this.

1v2 out still gets hot but with it out the screen bearly lights

1v2 out still gets hot but with it out the screen bearly lights

That is normal for no focus bias.

This leaves only 2 things, problem with the focus coil or L42 or something weird with the flyback transformer.

The path is from pins 1 -5, if the focus coil was somehow not resonating correctly, L42 would take the hit for it, or if somehow pins 5 &9 on the flyback were swapped, then focus coil/L42 would be overloaded.

Not really sure what it is here, this is a weird circuit.

It appears correct at the flyback 9 is horz centering that’s right and pin 6 is next to pin 5 and it’s right to the focus coil. If the ohms are correct the coil could still be bad ? The voltages 640 and 770 are at the right locations.

Pin 8 v6 should be 230v normally but as it stands it’s only 160v if something is not conducting in that tube maybe this is the voltage buildup I have the new 2.2pf cap just a thought even though I disconnected it before it won’t make a difference if the cap is bad. At this point I don’t know if I should put the old k1 in even though the resistance’s are not right unless I screwed up the one I made I don’t think so but never know all this is tied together video focus voltages.

The heating of L42 is unrelated to K1 or the state of V6, working or not, this was verified when you took C59/C60 out of the loop and it had no change on the heating of the coil.

So it has to be local to the FBT, focus coil and L42, but not the 1V2.

The heating of L42 is unrelated to K1 or the state of V6, working or not, this was verified when you took C59/C60 out of the loop and it had no change on the heating of the coil.

So it has to be local to the FBT, focus coil and L42, but not the 1V2.

I don’t know where a problem could be at the flyback I checked all the connections I didn’t want to miss anything at the flyback. Would a damper have anything to do with what’s going on here. So I wouldn’t think the 130pf would be bad.

Not sure what is going on here, I do not think it's the damper, could be C96, but not sure what unhooking it may do, the way they have this set up is strange.

Not sure what is going on here, I do not think it's the damper, could be C96, but not sure what unhooking it may do, the way they have this set up is strange.

That’s Motorola for you they had to be different

Guess I’m at a standstill.

Well I haven’t had a decent picture to set up the focus but I found that when the slug is out to much L42 seems to gets hot faster but when it’s in further it takes longer to heat up again I’m sure it’s supposed to get warm under normal conditions so until I get a good picture to focus I’ll leave the slug in more for now. So now I have to figure out what to use to keep the coil in it’s holder hot glue may not be good enough.

Epoxy?

Epoxy?

Well I want to make sure it can dissipate heat rather then trap it in. If the temperature don’t exceed the melting point of hot glue then it’s good.

Hot melt is a bad choice for holding such a coil, as it will get soft as it warms.
Better choice would be MG Chemicals - 8329TFF-25ML 8329TFF , thermal epoxy. $21
or silicone type 2.

Ok here’s what’s happening now the 770v tap is off the 640v tap but to make 640v it goes through a 47k but L42 is tied to the 640v tap befor the 47k at pin 1 on the flyback so there is almost 780v on both sides of L42 so I changed the focus coil it did nothing infact I had the antenna on and again it flickered clear and almost instantly L42 and focus coil got super hot. I don’t know what’s going on here I thought I had it with the position of the focus coil but something seems to be getting in the 640v tap I don’t know.

The boost tap is pin 7 (should be) , L42 is pin 1, which is on the bottom of that winding, so there should not be boosted voltage at L42, but only the base bias that's fed to pin one.

What you may want to do is double check the resistance of that winding.

.8 .5 .45 & 9 ohms for each taps .

The boost tap is pin 7 (should be) , L42 is pin 1, which is on the bottom of that winding, so there should not be boosted voltage at L42, but only the base bias that's fed to pin one.

What you may want to do is double check the resistance of that winding.

.8 .5 .45 & 9 ohms for each taps .

Yes pin 7 is for the most part pin 1 they are so close they should be the same there’s nothing between 1-7 that shows.

Yes pin 7 is for the most part pin 1 they are so close they should be the same there’s nothing between 1-7 that shows.

Incorrect.

It just looks that way due to artifact errors from the poor scan of the schematic, pin 7 skips over 1 & 2 and connects to the 3rd tap of the winding only, just under where pin 5 is.


it should be .5 ohms from 1-7.
or so it says on SAMS.

Flyback should be ok because it is making 640v and 770v so where is something crossed. Omg this set wow.

Without warm up just when screen lights up the 640v is 605v and the 770v is 760v didn’t check ohms yet but this looks ok I tested at the 10k and 47k.

Could the horizontal frequency be off in such a way that it would generate higher voltages and still be able to lock into video.

Not likely, if the horizontal frequency was off, then there would be no video lock, horizontal AFC and sync control will bring it into range for it to lock into the incoming video, but it has to be within the right frequency range in the first place to do so.

Something else is going on here, at this point, you may try to unhook one side of C96 to see if that has any change on the heating of the coil.
Can't think of anything else right now. :O

None of this makes sense one leg off c96 coil gets hot I don’t know where this coil could be getting a ground to heat up like this. It can’t possibly be designed this way that it would get this hot and I believe this may have something to do with the video in some way or another.

if you have not already, make sure R145 is still = 100K OHMS.

if you have not already, make sure R145 is still = 100K OHMS.

Yes checked r145 it’s still good so I’m thinking maybe overall this coil is supposed to get hot can’t see any other reason it’s getting hot it’s hard to believe that the coil stayed in it’s holder all these years with some kind of antique glue they used and now it’s falling out. I’m probably going to remove it and use hi temp silicone maybe it will stay in this time. If it burns well then i know that it’s 35ohms and 3600uh and hope I could find another if I need it.

This is L42 the coil itself is big compared to others in this tv.

The coils still look OK.

This is a bit costly, but should work.

Find a ceramic heat sink NOT metal, that can be glued to the coil, big enough to do it some good, small enough to fit under the chassis, use thermal conductive epoxy to stick it together, making sure the epoxy touches both the coil and heat sink.

Once cured, it should run cooler.
https://www.amazon.com/MG-Chemicals-Thermally-Conductive-Adhesive/dp/B07D18R5Z5/ref=sr_1_3_mod_primary_sns?keywords=thermally+cond uctive+epoxy&qid=1667332821&qu=eyJxc2MiOiIzLjgyIiwicXNhIjoiMy40MiIsInFzcCI6IjM uMzkifQ%3D%3D&sbo=GLaw0Fx56FiNH%2FiZ%2B6XKiQ%3D%3D&sr=8-3

example
https://www.walmart.com/ip/Whigetiy-20x20x5mm-Ceramic-Anti-static-CPU-Cooling-Heat-Sink-For-Raspberry-Pi-Orange-Pi/1005007799?wmlspartner=wlpa&selectedSellerId=101180981

There is absolutely no room for anything other then the coil lol �� I have 500 degree silicone.

There is absolutely no room for anything other then the coil lol �� I have 500 degree silicone.

you can get a small ceramic heat sink

Problem now is the coil measures 55ohms it’s not 35 ohms anymore so I guess it’s not supposed to get this hot more heat more ohms.

I have a Motorola book with a schematic note the500vpp pulse negative and positive where do these come and go.

Better picture. I had taken the focus coil out to change the horizontal centering pot but I took a picture of the coil so I wouldn’t put it back wrong so I know by the color of the wires it’s right. I can’t for the life of me find C3-C power supply cap I’m just checking if I maybe hooked it to the wrong source.

https://www.amazon.com/Ceramic-Cooling-dissipador-Raspberry-Orange/dp/B07VH3F9SQ 1/2 inch in size should fit nicely any replacement coil will be unobtainium, protect what you have while it still works, put a ceramic heat sink on it.

Right now I’m not going to plug this in until I can find C3-C capacitor to see where it goes because according to the Motorola schematic the L42 should only have 500v on it but I’m testing it has around 780v so I need to find where this cap goes maybe I placed it in the wrong place. This extra voltage on the L42 is not good I need to find out why.

Right now I’m not going to plug this in until I can find C3-C capacitor to see where it goes because according to the Motorola schematic the L42 should only have 500v on it but I’m testing it has around 780v so I need to find where this cap goes maybe I placed it in the wrong place. This extra voltage on the L42 is not good I need to find out why.

Incorrect. :(
the Motorola schematic is referring to the tie points on the flyback transformer, It's saying + and - 500v PP as in Peak to peak, that is not to be read as DC voltage ref to ground.

stick with the SAMs.
It's less confusing! :yes:

That Motorola schematic has some good additional information on it.... It would be cool
to know if those voltages are there, and correct. I was wondering if the focus voltage
is correct, and in the range that is printed on the Sams.... Can you turn the focus
coil and have a range of 4.3KV to 5.2KV ? I know with a HV Probe you will not
see much resolution, but it may tell you if things are OK enough to not
worry about that part of the circuit. Not sure how you would check
that Plus & Minus 500V P-P - I guess you can give it a try
with DVM and see what happens......

Also for L42 getting hot, you know each coil & Cap are a tuned circuit, If there is something
wrong, it may be peaking at a poor point and creating too much power.

All I can think of right now would be to check focus voltage as best you can.
Since the flyback was removed, it may be a good idea to try and see as best you
can that the pins that go where you think they go have the right resistance on
them as best as you can determine.

Take a picture, several pictures, of the flyback wiring, then disconnect all the wires,
measure the resistance of all the pins as you see them using both schematics, and
try and determine if it's wired correctly. You may also want to check resistance
from one isolated winding to another, This confirms no short between windings
and that they are wired correctly inside the transformer.... Since you have 2
Flyback transformers, you can compare between the two.....

My thinking is that since that flyback has pins that are tied to components and then
back to other parts of the flyback, that if a wire is not connected right, then voltage
may be fed to, or from one section out of phase, and causing problems, possibly
even heat on L42.

Does the flyback run hot?

I'm not sure I would switch any wires unless you have real good cause to do so,
you don't want to make anything worse....

With that coil measuring a higher resistance, it may be because it's been hot, and
starting to change because of that.... Or since there are differences on the resistance
measurements of some coils from one schematic to the other, it may just me
differences in their test equipment, or component tolerances.....




.

That Motorola schematic has some good additional information on it.... It would be cool
to know if those voltages are there, and correct. I was wondering if the focus voltage
is correct, and in the range that is printed on the Sams.... Can you turn the focus
coil and have a range of 4.3KV to 5.2KV ? I know with a HV Probe you will not
see much resolution, but it may tell you if things are OK enough to not
worry about that part of the circuit. Not sure how you would check
that Plus & Minus 500V P-P - I guess you can give it a try
with DVM and see what happens......

Also for L42 getting hot, you know each coil & Cap are a tuned circuit, If there is something
wrong, it may be peaking at a poor point and creating too much power.

All I can think of right now would be to check focus voltage as best you can.
Since the flyback was removed, it may be a good idea to try and see as best you
can that the pins that go where you think they go have the right resistance on
them as best as you can determine.

Take a picture, several pictures, of the flyback wiring, then disconnect all the wires,
measure the resistance of all the pins as you see them using both schematics, and
try and determine if it's wired correctly. You may also want to check resistance
from one isolated winding to another, This confirms no short between windings
and that they are wired correctly inside the transformer.... Since you have 2
Flyback transformers, you can compare between the two.....

My thinking is that since that flyback has pins that are tied to components and then
back to other parts of the flyback, that if a wire is not connected right, then voltage
may be fed to, or from one section out of phase, and causing problems, possibly
even heat on L42.

Does the flyback run hot?

I'm not sure I would switch any wires unless you have real good cause to do so,
you don't want to make anything worse....

With that coil measuring a higher resistance, it may be because it's been hot, and
starting to change because of that.... Or since there are differences on the resistance
measurements of some coils from one schematic to the other, it may just me
differences in their test equipment, or component tolerances.....




.
Before I had put the old flyback back in I checked resistance on it and it was very close for an old flyback. I do know the ohms are going up on L42 because of heating up. The flyback is cool no heat there. I had went over all the flyback connections several times they are good. I had a new flyback but it turned out bad so I put the old one back in. As for L42 I have to worry about that coil if I can’t get one if it burns I’ll have to check focus voltage.

The focus voltage is perfect and adjustable to sams specs. But the 6hs8 v6 has questionable voltages on 3 and 6 3 should be 2.5v but it’s only .3v and 6 should be 145v but it’s 111v and these pins have the 470pf and the 2.2pf caps these I think are for feedback and it don’t look like it’s doing anything otherwise the agc would probably work and I would have video. I question this because both caps have a wire one to L42 and the other to the focus coil so if these caps are not conducting in the circuit this could be affecting L42 and killing the video it’s all tied together.

You ran the 0v-9v volt sweep at test point A to show that it's not an AGC problem with the video, otherwise you would have seen a reaction on the screen as the voltage was changed at point A, and the gain was forced to change.

You said that you unhooked C59/C60 and there was no change in the heating of L42, so unless perhaps there is a fault in the wires between C59/C60 and the area of the flyback transformer /L42, the problem is still in the area of the FBT.

R13 alters the bias on pin 7 of V6 and R14 alters the bias on pin 6 V6, the balance of the 2 will alter the voltage on pin 3.

What you uncovered the other week, you do have an IF fault, regardless of if AGC is working correctly or not, 3rd IF is working, direct into 2nd IF works, but 1st does not, including L4 .
This has yet to be debugged.

The only one that changes is the noise gate r13 on pin 7

So these need to be closely checked, if they have not been already.

R62/R88/R91/R85/R87/R14

C60 side of R87 should be easy to test, resistance to gnd, 100k ish to 47k ish as r14 is adjusted.

R117 27k 3 watt is cold 6volts on one side and like 5mv on the other a 3 watt resistor don’t stay cold and should have a lot more voltage there then what it has now. And the agc pot does vary and the other resistors I had checked more then once.

The resistors mentioned determine the over all voltage seen on that pin, another factor is if there is video present or not, so don't expect to see EXACTLY what they say there on the SAMS.

What you got was most likely close enough, and once video is working, it will prob come up into what's on the SAMS.

V12 pin 1 is -8.5v and pin 9 is also -8.5v this is nuts and this looks like if I had video these voltages would straighten out.

Well bottom line here is I’m not convinced that there is actually a problem with the IF I believe there is stray voltage from somewhere and it’s corrupting the IF as well as overloading the focus circuit at the same time taxing the power supply. I don’t know where to look at this point. Diodes didn’t help anything. Like I said the video would flicker in and out and the hv would jump 4 kv and back down in an instant. Even though I got video at v2 it was still very distorted whatever this stray voltage is if it is maybe it’s affecting v1 and still carries on to v2 don’t know. When this set powers up there should be enough voltage to run everything even though the thermistor is warming up the voltage is just not there in the beginning and not always does the voltages come up to full after a few minutes it seems intermittent it’s odd never seen anything like this. I wish if there’s something shorting it would burn up that’s a way to find it.

I still had the issue with pin 8 v1 resistance check it should be 3.2k but it measured 6.3k this may be the key here since the set still don’t work I can’t say it’s a typo in sams every socket I checked were perfect except for the pin 8 v1. What is the likelihood of one of the old caps to ground that were not changed be shorted or should I say has this been seen before. The last time I checked v1 pin 8 it was 97v should be 100v v2 was 101v.

very likely an error, as V2 has an near identical bias on the pin and it's in the 6.3k range, but this has been pointed out before.

very likely an error, as V2 has an near identical bias on the pin and it's in the 6.3k range, but this has been pointed out before.

Yes they are nearly identical but v1 is not v2 there has to be differences between the 2 or they wouldn’t have v123 it’s just odd get some video on v2 but v1 nothing and that’s the one with a discrepancy. The difference between v1 and v2 is that v1 8.2 resistor goes to ground the 8.2 don’t go to ground directly on v2.

The reason for the bad video is that there is something out of tune between the input from the tuner, to the grid of V2, AGC has nothing to process, and therefore has no reference to set the gain of the circuit , but it is not an AGC fault, as was shown by the override test, the heating of L42 and any HV related issues, if they exist, are a separate issue entirely.


"The difference between v1 and v2 is that v1 8.2 resistor goes to ground the 8.2 don’t go to ground directly on v2. "

since the measurement is not taken from ground reference, but from the main power point, this difference is infinitesimal, very high chance the SAMS is wrong and the 6k reading is correct for both.

Ok so let’s say it’s a sams mistake and leave it at that I already mentioned that the video would pop in clear and then gone so v1 there’s really nothing there except a few resistors and a few coils so I can’t believe that those coils were touched because the video at random would pop in and then be gone again. So what’s really left to check. Perhaps the .001 cap in L4 is bad the coil couldn’t conduct properly if that cap is bad.

The IF is the most sensitive tuned area of the set, having RC constant circuits, that are going to react to voltage and temperature, and you have no clue as to what was done to it before you got it.

It's not unusual for something that is out of alignment to briefly pass a signal as it starts up while voltages and things are cold, but stop as it gets into normal ranges.
Thus alignment is done when the set is warm.

HELL, all my sets that are able to tune in stuff take 60-90 seconds before the can tune correctly, then they run OK for hours, what you see in the first few moments does not mean anything.

Have you cleaned the tube pins? Is the socket ok? :scratch2:

jr

The IF is the most sensitive tuned area of the set, having RC constant circuits, that are going to react to voltage and temperature, and you have no clue as to what was done to it before you got it.

It's not unusual for something that is out of alignment to briefly pass a signal as it starts up while voltages and things are cold, but stop as it gets into normal ranges.
Thus alignment is done when the set is warm.

HELL, all my sets that are able to tune in stuff take 60-90 seconds before the can tune correctly, then they run OK for hours, what you see in the first few moments does not mean anything.

Oh I understand what you’re saying but this is when it was already warmed not just turning on so I don’t know I have new .001 caps maybe I’ll try one in L4 and see what happens. If that don’t work then maybe I’ll disconnect L4 and check resistance and see what comes up.

Have you cleaned the tube pins? Is the socket ok? :scratch2:

jr

I checked the pins and tightened them a bit move the tube side to side no change

Would an RF fixed 3600uh inductor the same is a peaking inductor 3600uh

I kind of overlooked at L4 that it has 2 .001 caps where L5 only has one the 2 in L4 one is red and the other is regular color ceramic disc the red one may be a mica won’t know til I get up close a personal with it. So now there’s 2 possible reasons for no video.

If it's intermittent it could also be one of the tuner inductors has a lead that either isn't soldered or corroded badly enough that it's effectively open and only gets continuity occasionally. Intermittent conditions often spawn in unusual places.

Since mica caps are used a lot in rf circuits it looks like it’s probably a .001 mica cap is on the primary of L4 makes sense to have a perfect signal to send down the IF line.

The difference between ceramic disc capacitors and mica is easy to spot, a pic of the caps in question would help.

But do remember, if you ARE thinking of replacing the .001 disc capacitors, don't use any old caps, but be sure to get C0G (NP0) type, it will save you from a whole world of pain down the line.

Well I was not going to touch L5 cap seeing it works already and the questionable problem is in v1 L4 hopefully. All I can say at this point is the primary side of L4 has a red cap and the secondary side has a regular color disc cap and it’s so tucked in there tight I can’t even get a picture to show it. So I’ll try the secondary side cap first if it Works then great if not then I may have to take the coil out of the housing that it’s in.

I don’t even have a 1000pf mica I have micas that I can make up a 1000pf but then I have to leave it out of the coil housing don’t know if that’s acceptable or not.

Before doing anything to L4, you should try what others have suggested, V1 removed, and feed in the tuner subber into pin 7 the same as you did before, through a isolation capacitor, to see if you can get any signal through, you may have to adjust the gain on the subber a bit.

possible choices.

https://www.mouser.com/ProductDetail/TDK/FA24C0G2W102JNU00?qs=zFwFjAF3uagZ5aznO8lXZA%3D%3D
https://www.mouser.com/ProductDetail/Cornell-Dubilier-CDE/CD19FD102JO3F?qs=PXF%252Blbo4VJ4mEFdco7WMcA%3D%3D


Mica caps are NOT cheap! :tears::no:

Before doing anything to L4, you should try what others have suggested, V1 removed, and feed in the tuner subber into pin 7 the same as you did before, through a isolation capacitor, to see if you can get any signal through, you may have to adjust the gain on the subber a bit.

I had taken v1 pin2 off L3 and fed the subber in got the same as befor and with that wire off L3 I tried pin 7 but the tube was in and I got less of a response. When I fed v2 I used pin 2

It would most likely work better for you to put the original K1 couplet back in, as the 24meg section was not really that far off to matter that much to start with, and replacing it did not really do much.

It would most likely work better for you to put the original K1 couplet back in, as the 24meg section was not really that far off to matter that much to start with, and replacing it did not really do much.

I already put the original k1 back in problem with it is the 2.2meg measured 2.4meg and the 2meg measured 2.4meg the 24meg measured 30meg and the 680k measured 740k this is why I made it up so I’ll leave it in for now and it may not be needed at all.

I already put the original k1 back in problem with it is the 2.2meg measured 2.4meg and the 2meg measured 2.4meg the 24meg measured 30meg and the 680k measured 740k this is why I made it up so I’ll leave it in for now and it may not be needed at all.

https://www.allaboutcircuits.com/tools/resistor-color-code-calculator/

that's all pretty much within 20% save for the 24 meg, which is just a hair.

most people say it's safe to let it go to 30%, then worry about it.
tube stuff is very forgiving with this! :D

I do have a 1000pf mica from the 1940s for test purposes it tests like new exactly 1.00

I would never trust it in a 60s type set, especially in the RF area, no idea what the voltage rating is, but it is a neat souvenir however! :)

Rather then use that old mica can modern micas be put in parallel to make the right capacitance. I know it’s the IF so it can be touchy.

Rather then use that old mica can modern micas be put in parallel to make the right capacitance. I know it’s the IF so it can be touchy.

Doing that in an IF is not recommended...

the cap I pointed out IS the right capacitance, .001 @ 500v

598-CD19FD102JO3F mouser part #

So if the red cap that’s in L4 if it’s not a mica but rather a special type ceramic disc then replacing it with a mica should be better for the circuit.

Going to try 2 disc caps in v1 see what results I get if it works then when I get the mica cap then I’ll put it in. Regular disc cap should work in place of a mica if that’s infact what’s in there hopefully I get a good result.

If you are thinking of trying 2 capacitors in parallel, then that would not be advisable on a IF circuit, as it would drastically change the rc constant of it, and make it worse than when you started.

If you are thinking of trying 2 capacitors in parallel, then that would not be advisable on a IF circuit, as it would drastically change the rc constant of it, and make it worse than when you started.

No I’m going to try the 2 .001 ceramics in L4 to see what the result is hopefully video. Ordered the micas if it’s good then I will put the mica in.

Ok tried the 2 .001 caps in L4 made no difference but v1 pin 8 is 100v but pin 7 is only 200v should be 210v after a couple of minutes and the 275v buss is only at 260v I cannot figure out why this b+ is low something here still seems to be pulling it down. The voltages are the same on v2.

Look in the parts list in Sam's and see if there's temperature constants listed for the original caps. When permanently replacing caps in tuned circuits especially original ceramic in the IF you want to use the same temperature coefficient. Sometimes a coil changes inductance a meaningful amount when it heats up and a cap is chosen with a temperature coefficient such that the cap changes value in step with the coil such that the tuned frequency of the pair remains constant despite the R and C values shifting with temperature.
Temp codes are typically 2 letters and a number like C0G, NP0 which are no change temp constants.

Ok tried the 2 .001 caps in L4 made no difference but v1 pin 8 is 100v but pin 7 is only 200v should be 210v after a couple of minutes and the 275v buss is only at 260v I cannot figure out why this b+ is low something here still seems to be pulling it down. The voltages are the same on v2.

you are putting too much emphasis on the voltages posted in the SAMS, it's not unusual for there to be variances of 10-15% or even more and it being perfectly fine, no two sets are alike, even more so as they age.

Ok upon turning on voltage starts high of course then it steadily drops the 275v dropped 226v then momentarily went up 260v ok well again I’ll leave the voltages alone but now back to the video problem with the test caps in place I removed the ground for a moment and made really no difference just alittle snow dots that’s it. Batteries are dead in the subber they don’t last.

The antenna put in at v1 pin 2 but v1 pin 7 it’s a better picture v2 pin 2 about the same and pin 7 no video. I put the new focus coil in and it along with L42 is still getting really hot if I leave it on long enough it’s got to burn up L42 and the focus coil. I can’t help but think these 2 problems video and overheating L42 and focus coil are related.

Not exactly sure what you are doing here, "The antenna put in at v1 pin 2 but v1 pin 7 it’s a better picture v2 pin 2 about the same and pin 7 no video."

this is a bit hard to follow :O

Not exactly sure what you are doing here, "The antenna put in at v1 pin 2 but v1 pin 7 it’s a better picture v2 pin 2 about the same and pin 7 no video."

this is a bit hard to follow :O

The better pic is v2 pin 7 and the others I do get some video it’s better if v1 tube is left in.

At this point I feel like I’m chasing something that I may not find because with L42 overheating and focus coil overheating I probably think I should put my time into finding out why these are overheating.

The 770v tests 780v the 640v tests 620v the crt anode brightness down 24kv I don’t even know if L42 is supposed to have 780v on it I’m alittle lost not knowing the proper voltages that should be there it’s obvious there is to much voltage there.

For that you will have to do as SB suggested.
======
Also for L42 getting hot, you know each coil & Cap are a tuned circuit, If there is something
wrong, it may be peaking at a poor point and creating too much power.

All I can think of right now would be to check focus voltage as best you can.
Since the flyback was removed, it may be a good idea to try and see as best you
can that the pins that go where you think they go have the right resistance on
them as best as you can determine.

Take a picture, several pictures, of the flyback wiring, then disconnect all the wires,
measure the resistance of all the pins as you see them using both schematics, and
try and determine if it's wired correctly. You may also want to check resistance
from one isolated winding to another, This confirms no short between windings
and that they are wired correctly inside the transformer.... Since you have 2
Flyback transformers, you can compare between the two.....

My thinking is that since that flyback has pins that are tied to components and then
back to other parts of the flyback, that if a wire is not connected right, then voltage
may be fed to, or from one section out of phase, and causing problems, possibly
even heat on L42.
====
Mainly pins 1 & 5.
Others may be involved, but 1&5 hook directly to L42 & the focus coil, and must be unhooked to get a good reading, which SAMS says is .45 ohms, I think.

Before I put the flyback back in the resistances we’re good and the focus voltage measured perfect. And the other flyback I determined was bad I couldn’t get the hv right that why I put the old one back in and before taking the old fly out I drew a picture of the wires and colors where they came from and that’s how I put it back. So if it’s determined to be right and resistance is good then I’m still looking for a problem.

never hurts to double check stuff, cause there has to be a fault local to the FBT & focus area someplace.

never hurts to double check stuff, cause there has to be a fault local to the FBT & focus area someplace.

I traced all the wires before and they all were good so next I’ll pull the chassis and disconnect all wires and check resistance on the flyback. I just checked the new flyback I have and all the coil taps check perfect but the donut checks at 470 ohms but the paper with the resistances it came with says it should be 640 ohms is that close enough.

I traced all the wires before and they all were good so next I’ll pull the chassis and disconnect all wires and check resistance on the flyback. I just checked the new flyback I have and all the coil taps check perfect but the donut checks at 470 ohms but the paper with the resistances it came with says it should be 640 ohms is that close enough.

too low, pin 12 to the cap of 3AT2 should be at least 600, so it has shorted turns, or is the wrong part. :scratch2:

too low, pin 12 to the cap of 3AT2 should be at least 600, so it has shorted turns, or is the wrong part. :scratch2:

Ok well that explains why I couldn’t get the hv right. I checked the donut on the original fly it’s 582 ohms so that’s good then I hope. I’ll be tracing wires again and checking resistances on the old flyback.

Donut 585ohms
1-2 .9
7-2 .6
5-7 .6
8-6 1.0
11-12 1.0
13-14 1.1
9-5 9
2-5 .8
5-2 1 I wasn’t able to get .45

something weird there, not really sure what, it SHOULD match the replacement, IF they are the same FBT.

The new flyback I have gives resistances and there are alittle different then the sams but that fly I can’t use if the donut tests bad that’s the flyback that kept red plating the hot. The numbers do match for the replacement flyback

Replacement sheet

if they both match from pins 1-5 then this has gotten very strange THOSE are the pins that matter most.
the resistance between 1 and 5

Are you referring to the .45

Pins 1 and 5 measure 1.6 ohms

Pins 1 and 5 measure 1.6 ohms

on both the new and old?

on both the new and old?

The new flyback 1-5 1.6 ohms same as old one

That one section with the .45 is weird how those coils are configured.

So I guess it’s not a good idea to use this flyback. So I got a line on another new one so I’ll chance another one. The new one that’s no good is a stancor and the one I’m going to get is a thordarson.

I’m not sure why 1&5 would be so important because I do have both boost voltage’s so if those 2 taps were shorted in some way the voltages should be way off at last check 640v was 620v and 770v was 780v that don’t seem to bad but it sure doesn’t explain why the focus circuit is hot even though focus voltage is right and variable via focus coil. And the 66meg stick resistor for focus gets alittle warm as well.

the AC current path of L42 was the reason for looking at the resistance of pins 1-5

http://suzaku.live-evil.org/L42.jpg

not really sure why it's hot if both FBT match, but this may be related to why the 100k ohm resistor burned in the first place.

the AC current path of L42 was the reason for looking at the resistance of pins 1-5

http://suzaku.live-evil.org/L42.jpg

not really sure why it's hot if both FBT match, but this may be related to why the 100k ohm resistor burned in the first place.

I had a silvertone that burned the resistor also. Is there a possible reason for the hot L42 from either the horizontal centering circuit or hv regulator like a bad cap. The centering boarders pin 5. Other then that would you use this flyback with the specs it has and the donut 585ohms.

C99 shows.25 but what came out was a .5 this shouldn’t make a difference unless I messed up.

Well it’s official I put the wrong cap in c99 I put a .5 in instead of .25 I don’t know if this may cause the L42 issue along with the video issue

Well it’s official I put the wrong cap in c99 I put a .5 in instead of .25 I don’t know if this may cause the L42 issue along with the video issue

Which would have caused the pulses to be 2x higher then they should have been at that coil , you may want to test r136 too.

Lucky I saved all the caps I changed and there is only one .25 400v c99 and that’s the one I put was wrong. Hopefully the L42 will be ok now and maybe I’ll get video because the pulses pass v6.

Well sorry for driving you guys crazy but it’s not a mistake the .5 is next to the .25 I looked at the wrong one my glasses are not working for me. .25 is in place and checks good. Back to square one again.

I don’t know if these new caps these days are any good but the original cap checks better then the new so maybe I should try the original cap it’s +20% and see what follows.

The 10ohm resistor is 11.3ohms

I don’t know if these new caps these days are any good but the original cap checks better then the new so maybe I should try the original cap it’s +20% and see what follows.

if the OLD is paper, do not trust it.

now the question remains, is the IF problem still there or not?

I'd guess it's a 50/50 chance. :(

If I only had an idea what it is that tunes the focus coil. All there is focus coil L42 .25 cap 10 ohm resistor that’s it.

The old cap is those dark red ones. I have to concentrate on this focus issue before getting back to the IF because the L42 is going to burn up then I’m screwed.

The IF problem is still there

If you are so worried about the L42 Temp. then just put a 10 Ohm 10W resistor in
series with it, and check it's temp. and move on till you get a pic on the screen
and then you can figure it out.... I mean like a Good Pic from the tuner
with everything else working.....


I also doubt that any cap. that you replaced where the value is .1 and you put
in a .5 by mistake is causing all these problems... I hate the idea of using a
parts cannon on all these tv's before you get it working by only replacing
electrolytics, but that's what you guys end up doing....

This should be your main focus:

Every TV without a signal should produce snow on Picture & Sound
this one does not. You tracked the signal loss to a specific area, & now
need to focus on why it's getting lost. IF Amp not working? IF amp
turned off because of some AGC Fault?



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If you are so worried about the L42 Temp. then just put a 10 Ohm 10W resistor in
series with it, and check it's temp. and move on till you get a pic on the screen
and then you can figure it out.... I mean like a Good Pic from the tuner
with everything else working.....


.

I thought of doing that but there’s a reason why this is happening and I really wish I could get to the bottom of it then move on to video maybe this problem is related to the video problem.

It is entirely possible both problems are related.... But which is the chicken, and which
is the egg..... And is there a 3ed or 4th problem in there too.....
To figure out what is going on with L42 you might just have to look at wave forms
especially that + - 500V P-P as it would be most telling as to the health of that
circuit. Flyback not hot +, Focus voltage within range +, Screen is focused when
signal makes it through from test points +.

You don't know what that coil's temp is when it working perfectly, like when it
came from the factory.....? Did it run hot anyway...?



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