Well, here I am rolling along on BigAudioAl's Admiral. Complete recap, etc. Here's where I'm at. Thoughts?

http://www.youtube.com/watch?v=5qgng8DixKY&feature=youtu.be

Have you either tested the vertical output and oscillator tubes or substituted them with "known good" tubes. Sometimes the substitution method is the best; that way there is no question about the electronic integrity of the vacuum tube.

There are so many possibilities that I guess people will hit on with this common symptom of no vertical sweep. I think that the next most important question to ask you would be: Was there vertical sweep before the "recap?" You could have a bad vertical output transformer, a potentiometer or a bad yoke. There are resistors across the yoke windings that can bad or have cold solder joints.

I'll stop there so some others can maybe elaborate. I hope this helps.

I didn't plug it in before the recap. The caps looked horrible, and I didn't trust them....I knew from experience that there was no way I was gonna get anything on screen unless I replaced those 6 kV deflection caps, anyway.

The only thing in the entire set that looks like a real abortion is the horizontal sweep transformer. New leads soldered on inside, and a wrapping of black tape on the outside. I'll assume that it's working though, since it has horizontal sweep.

I'll try tube substitution next. I just thought that it was really odd that I'm getting what sounds like horizontal sync bleeding into the audio.

The high megohm resistors near the vertical size control are reasonable suspects... I have seen the 10 meg ones *really* increase in value and kill the vertical, but the others are also suspect. Might want to ohm check the vert osc xfmr as well. Good Luck!
jr

Sounds like you are good for now in the horizontal realm with the exception of that audio/horizontal noise that you describe. That description of new leads being soldered on and "a wrapping of black tape" around the flyback transformer sounds scary and may be the heart of that noise you are hearing.

However, nothing in the horizontal circuitry is going to bring back the vertical sweep. Try the tube swap first, then work from there. Good luck.

I don't see a yoke, flyback transformer, or vertical output transformer on my schematic for an Admiral 19A1... It is a 7" electrostatic set. :)
jr

Someone mentioned to me that you can't use disc caps for the 6 kV vertical deflection, but they'll work fine for horizontal. Seems to me that I remember using disc caps for a VT71 I did years ago.

I'll hop on it tomorrow again and check those resistors. Thanks for the advice :)

Someone mentioned to me that you can't use disc caps for the 6 kV vertical deflection, but they'll work fine for horizontal. Seems to me that I remember using disc caps for a VT71 I did years ago.

I have used them also, for both Horizontal and Vertical coupling to the deflection plates. They worked ok, but with perhaps a little change in height/position as the set warmed up... no biggie... and certainly did *not* kill the vertical sweep.
jr

I don't know about the tv, but after yer video there was this GIRLFRIEND ZOMBIE ATTACK video I just had to see, and then I forgot about your tv a little more....

http://www.youtube.com/watch?v=PIVtr5kYvmU

Give it a try, you'll forget about that tv......

What TV were we talking about that was awesome.... seriously though I had the same exact set check the linea te controls on the back. they usually need a really good cleaning in my case it was simply burnt open I replaced it and the tv went back to normal. as for the black tape on the transformer be extremely careful I mean extremely careful the winding on that transformer use wire that is about the size of a human hair. my Transformer failed shortly after the set begin to make a quiet squealing sound I managed to solder the broken wire but when I moved it by accident it broke way back by the core my set is now DOA until I can find another transformer.

And believe it or not that could also be a tuner issue

First question is on capacitor C2B, the 50 uF section of the big white or tan filter cap under the bottom. I need to know where this goes, along with a couple pictures of the wiring at the end of said red wire.

Greetings from FixitLand!

No one's said this yet, surprisingly, so -- PLEASE turn the brightness DOWN on that set while it's showing only a bright horizontal line, lest you burn that line permanently into the phosphor!

Good luck on the fix,
--
J. E. Knox "The Victor Freak"

That is turned down. I played with the shutter settings on the camera.

As to the vertical circuit: once you get it working at all, I have a suggestion
for it that resulted in "oohs" at the picture it made on my lowly Pilot TV-37,
which has the same circuit idea.

My change was to replace the capacitors feeding the vertical deflection
plates with much much higher value 6kV ceramic ones. Actually my
set could use 3 kV ones but yours need the 6kV ones.

I would suggest 0.05 uF but 0.03 would work. Parallel cheaper
ones if necessary. Its still not terribly expensive. What this does
is increase the time constant of the circuit so that there is no
"exponential droop" during the 1/60 sec. scan time. Then remove the
odd 20 meg resistor between the vertical oscillator plate and the
second vertical output plate.

The waveforms on the plates of the two output tubes will then be
much more linear than the very odd ones shown on Rider's (
and which were similar to those on my Pilot before the mod.) And due
to the much larger capacitors they will be essentially identical on
the picture tube deflection plates.

Sorry to thread-crap Tim, but it seems that you haven't been reading (tracked) PMs, and I'm concerned about the remotes that you're forwarding to me. I just thought I would have heard something by now about what shipping will be for those and the other stuff. As long as you know where they are, I'm good.

I've been really busy with other things around the house and haven't had chance to get them forwarded yet. I'll respond to you in a sec.

The set as it is uses 6 kV caps.....right now I have to figure out where one of the four tuner wires goes, and I can't do that without taking the drum out of the tuner and tracking the schematic. Gonna be cold and snow is in the forecast here for the week, so I may end up staying on this set for a bit. My Mouser order for another set won't be in until late in the week for my Zenith 23 H chassis.....

No prob, it's all good, I was just concerned that they may have been lost somewhere around there. Probably my OCD.

Anyway, I saw the video and was surprised that it was a mere 2-meg download. Following this thread for sure to see the conclusion.

Well, now I've got this spare chassis in hand, and have figured out where all the loose wires go.

Attached them, and now nothing but a bright dot on the screen, no sweep whatsoever. I was able to blur it out with the focus control to the size of a quarter, but I couldn't even dim it down with the brightness control. Shut it off after about 30 seconds.

Why does it feel like I've taken a huge step backwards......

Tim,
My 19A1 did not like GTB tubes. Caused problems with one of the sweeps (vertical I think). Putting in older GT/GTA tubes worked better.
I have the same set in almost working condition (it has some wiggling of the picture) if you need any wiring pictures.

Maybe for vertical sweep, but I *did* have horizontal sweep before hooking up the one errant wire in the tuner, and before I realized that another wire was grounding out to chassis. The next step here is to pull the tuner drum and see what's going on with the wiring in there. I noticed that one of the wires inside the tuner was coming out the wrong hole, meaning that someone was in there fooling around at some point.

Did your set lose sweep entirely with the GTB tubes?

Swapped the entire tuner assembly from a parts chassis with no change whatsoever.

I'm stumped as to where to start. When one wire was unhooked from the tuner and another was (possibly) grounded to the chassis, I had horizontal sweep, and audio of some kind. Now with the wires hooked up properly, and even subbing a different tuner assembly, I've got zero sweep of ANY kind (just a super bright dot, I had to pull it way out of focus and dim it of course), and zero out of the audio.

Thoughts? :dunno:

Good luck! Hope someone has some suggestions.

For the time being I'd leave the tuner out of the picture. Check that all your B+ voltages are correct, then focus on getting your horizontal and Vertical oscillators running first.

Voltages are all screwy. I've got 295V on pin 3 of the 6V6 (should be 220VDC), and 261V on pin 4 (should be 200 VDC). Also showing 262V on pin 2 of the 6SL7 vertical output (should be 210 VDC). I've yet to find any negative voltage. Bear in mind also that my experience level isn't as high as a lot of you, but I'm learning quite a bit.

This set was a real hack job when I got it, so at this point anything could be suspect.

Voltages are all screwy. I've got 295V on pin 3 of the 6V6 (should be 220VDC), and 261V on pin 4 (should be 200 VDC). Also showing 262V on pin 2 of the 6SL7 vertical output (should be 210 VDC). I've yet to find any negative voltage. Bear in mind also that my experience level isn't as high as a lot of you, but I'm learning quite a bit.

This set was a real hack job when I got it, so at this point anything could be suspect.

High voltages on the plate of the 6V6 seem to indicate the tube is not conducting. The question is now why? How about the grid and cathode. Are they where they belong?

Can somebody post the schematic? The screwy voltages sound like the audio output stage is used as B+ dropper for the IF strip, tuner etc.

http://www.earlytelevision.org/pdf/Admiral-19a1-sams-59-2.pdf

I can get back to checking the rest of the voltages, etc, tomorrow.....

Can somebody post the schematic? The screwy voltages sound like the audio output stage is used as B+ dropper for the IF strip, tuner etc.

Yep. There's suppose to be 125vdc on the cathode (pin 1) of the 6AS5 audio output. 210vdc on the plate(pin 7).

Everything seems to be running high. I've got 179 VDC on pin 1 and 286 VDC on pin 7.

That's strange. What's on pins 2,5,6 while you're at it? Got another 6AS5 to try?

166 on pin 2, 164 on pin 5, 293 on pin 6. Might have one laying around here.

Better check R48,R49 too. Those two resistors bias the grid.

Pin 2,5 should be about half of whatever's on pin 6 - because the voltage on pin 6 should be basically divided in half by the 470k and 560k resistors in series going to ground. The grid(pins2-5) get's it's bias from the junction of those two resistors. Not sure why your source feeding pin 6 is so high. You might go back and measure the AC voltage on pins 4,6 of the 5Y3. Suppose to be 240vac from each pin to ground. Then 240vdc on pins 2,8.

R48 is high....should be 560K, it's reading 704K. R49 isn't terrible, it should be 470K, testing at 496K. I should have that value here to replace.

704k isn't that far out. Basically your measured 166v is roughly half of 293v.
Better back up and measure AC volts on pins 4,6 of the 5Y3 - should be 240vac each pin to ground. Then 240vdc on pins 2,8. What's your AC line voltage?

With the resistor changed to 550K (closest I could come), voltages dropped to exactly 152 on both pins 2 and 5. Still no changes otherwise, not that I'd have expected there to be at this point :)

704k isn't that far out. Basically your measured 166v is roughly half of 293v.
Better back up and measure AC volts on pins 4,6 of the 5Y3 - should be 240vac each pin to ground. Then 240vdc on pins 2,8. What's your AC line voltage?

Pins 4 and 6 are at 280 VAC, and 2 and 8 are at 310 VDC. Line current is 118 VAC.

That seems awfully high. Honestly I'm not familiar with how much current the HV oscillator circuit pulls from the LV supply on this set. Possibly if that's not running and producing HV, that it's making the other B+ voltages high. It's as if there's hardly any load on the LV supply. :scratch2:

Read back and didn't see where you measured voltage on pin 3 of the 6V6 HV osc. Sams says 3 volts, which would be 30ma across that 100 ohm cathode resistor. I suppose that's a significant part of the total load on the LV supply? Were these supply voltages always high, even when you had HV?

I still have HV, just no sweep whatsoever. The dot in the center is horrifically bright, the only way I could get it so that it wouldn't put a nasty ion burn on the screen is to bring it way out of focus. Brightness control has zero effect on it.

Have you've checked the brightness control, and the 1M resistor coming off it's center tap? The brightness pot is fed by the same B+ on pin 6 of the 6AS5. The voltage on pin 2 of the CRT should vary from 72-180v(according to Sams) with rotation of that control. Make sure you don't accidentally measure the HV with your VOM.

I'll get on that tomorrow morning and let you know my findings. It's 19 degrees out, and I'm pooped out from moving DuMonts in the cold that weigh as much as a conversion van ;)

My Sams is showing me that the 6V6 should have 3 VDC on pin 8. I've got 6.32. On pin 3, I've got 281 VDC, should be 220.

And now, seems I've lost raster......

My Sams is showing me that the 6V6 should have 3 VDC on pin 8. I've got 6.32. On pin 3, I've got 281 VDC, should be 220.

And now, seems I've lost raster......

:wave: Tim , If this is the same set that's been kickin yer nuts with the selenium replacement and such , here's my offer ;

Next time your gonna be in eastern Mass. PM me and we can spend a couple hours going over it together . I may not be a total rocket scientist , but I did work in radio/TV repair back in the 60s and 70s (and as a special bonus I CAN even spell "rocket scientist" :D )

Definitely will! Wife and I take a LOT of road trips.....we usually combine our interests....she'll look up a Diners Drive-Ins and Dives restaurant, and I'll manage to work a TV in there :D

Nope, different set though.....this is a little 7" from the late 40s. The other one's a Sylvania Halolight.

I quit on the Admiral today, and I've got the RA113 on the bench, doing some more caps. Perfect day for it too.....20 degrees and windy with light snow outside. Wife is working (she does freelance transcription), and I'm all toasty in the basement with my soldering iron, my old Perfection kerosene heater, and a snoozing cat. Sundays were meant to be just like this :)

Can we assume the brightness control checked out OK, along with the 1M coming off it's center tap?

Have you've checked the brightness control, and the 1M resistor coming off it's center tap? The brightness pot is fed by the same B+ on pin 6 of the 6AS5. The voltage on pin 2 of the CRT should vary from 72-180v(according to Sams) with rotation of that control. Make sure you don't accidentally measure the HV with your VOM.

Resistor is measuring 1.13 M, so we're close anyway. Brightness control is within spec. Now, here's the odd part.

I noticed on the brightness control there is a wire that is attached to the terminal of the brightness control opposite chassis ground, that goes right to one half of C1.

My parts chassis does not have this wire.

The plastic on the end of the wire where it attached to the brightness control appears to have melted, and the wire was disconnected. Granted, it could have melted from the previous owner's soldering iron, but I get lost in the schematic right at that point trying to figure out if it should even BE there, as the junction spiders out everywhere.

:dunno:

Definitely will! Wife and I take a LOT of road trips.....we usually combine our interests....she'll look up a Diners Drive-Ins and Dives restaurant, and I'll manage to work a TV in there :D

Nope, different set though.....this is a little 7" from the late 40s. The other one's a Sylvania Halolight.

I quit on the Admiral today, and I've got the RA113 on the bench, doing some more caps. Perfect day for it too.....20 degrees and windy with light snow outside. Wife is working (she does freelance transcription), and I'm all toasty in the basement with my soldering iron, my old Perfection kerosene heater, and a snoozing cat. Sundays were meant to be just like this :)

:thmbsp: Cool , Sounds Great to me . If you are coming anywhere near Boston just give me a PM a day or two in advance so we can meet up . I am sincere in my offer of help when ya got a tough one , like I say I ain't God's gift to all things electronic but I do have a pretty good way with diagnosing and repair of our beloved tube sets .

From the Sams, it appears that the high end of the brightness pot should connect to C1-b. Does the wire indeed go to the "b" section of the cap? Perhaps the set that you are working on has a less obvious connection path... ohm it out, I bet the high end of the brightness pot is indeed connected to C1-b

jr

Agree with JR that the end opposite ground needs to be connected to + side of C1-B. You need that variable control voltage on the CRT's cathode(pin 2) in order to change brightness.

Gotcha. I guess the parts chassis was more of a parts chassis than I thought.

I'll resolder the wire and proceed with the voltage test on pin 2 of the picture tube.

Okay, now we're getting somewhere.....

Powered up after resoldering the wire, and shortly thereafter, a small POP....not big enough for me to shut the set down right away, but now I've got sweep of some kind FINALLY!

Same audio buzz is back in the speaker as in the video. High pitched whine coming from the chassis....I'm not sure if it's the horizontal oscillator going at warp speed, or what. Didn't see anything obvious in the POP, but I assume the next step is to start rechecking my voltages?

Yeah, you've at least got horizontal and vertical sweep now. It'd be interesting to see if your supply voltages came down closer to spec, now. From here it looks like you don't have horizontal lock, so that may be all that's keeping you from getting a stable picture at this point. Hard to say about the pop noise. Sometimes a control can arc if the riveted terminals are making poor contact with the resistance element, or the wiper itself could have poor contact. Does the brightness control appear to be working correctly now?

Sure does! In fact, the set is now passing signal......I've got vertical lock, and perfect audio! :D

The horizontal is all messed up, though. There's a flat spot on the horizontal size control that's, well, most of the control. I'll ohm that out later and change it from the parts chassis if needed be.

Weirdly, the audio level is affected by the contrast control. I know in some of these sets, the circuits affect each other, is that the case here?

Yes! the contrast control varies the gain of the video amp, and the sound IF is driven off the plate of the video amp (through a 2 uuf cap) so contrast will affect the sound.

jr

The POP mighta cleared a tin whisker.

The POP mighta cleared a tin whisker.

Good point. I've yet to find a control with a tin whisker, which I guess makes me a TV tech rookie. :D

Here's where I'm at now :)

http://www.youtube.com/watch?v=7MkX8nn28yQ&feature=youtu.be

Looks like multiple foldover to me. Any chance you installed a cap that's off by a 10 factor? If so the horizontal osc could be running at some higher multiple frequency.

When you change the horizontal hold, it appears that you're actually get lock at more than one higher frequency.

That's what I was thinking too. I was pretty careful about that, but I suppose anything's possible. I'll double check my work.....

Everything seems fine....

One thing to note....I can't get more vertical out of it than I've got.

Got any more 6SN7s and 6SL7s to try? how are the dc voltages in the vertical & horizontal circuits?

jr

Tubes tested good, replacements yielded no change. I'll test circuits as time permits this evening. Really appreciate you guys sticking with me in this thread :)

The POP mighta cleared a tin whisker.


I know that I am 24 hours "late for the party" but that very symptom had me pulling my hair out on an Admiral 26R12. It was on the height control. The clue which I failed to pick up on was that varying the control did not change the voltage. The set started out good. But then there was a "POP" and I lost about half of the vertical height. To me, a lesson learned. I was not familiar with tin whiskers at that time. So, you may be good to go for that.

You may want to try brushing the controls G E N T L Y to get any tin whiskers away. They can be from the terminals to the control case and drive you crazy.

In the schematic for chassis# 19A1,
There's four components in the H. osc circuit which, if they've been replaced and one were inadvertently the wrong value, could throw the frequency 'way off. They are:

C36, .01 uf. comes off pin 6 of H. osc tube
C37, .001 uf. connects between yel. and brn. leads of T4
R42, 39K goes to pin 5 of H. osc tube
R43, 39K goes to pin 4 of H. osc tube

(color code for 39K = orange-white-orange)

C36 in my Sams is a .002@600, "de-emphasis", and C37 is a .005 audio coupling cap. I'm working with set 59, folder 2, date 4/49. Matches what is in my set.

I'll just check those specific caps and resistors. Hang tight.

Okay, my diagram numbers them C46 and C47. C46 is fine, C47 is an original Micamold that I never replaced. Time to give that a try.

In the schematic for chassis# 19A1,
There's four components in the H. osc circuit which, if they've been replaced and one were inadvertently the wrong value, could throw the frequency 'way off. They are:

C36, .01 uf. comes off pin 6 of H. osc tube
C37, .001 uf. connects between yel. and brn. leads of T4
R42, 39K goes to pin 5 of H. osc tube
R43, 39K goes to pin 4 of H. osc tube

(color code for 39K = orange-white-orange)

Translation to Sams numbers

C36 = C46
C37 = C47
R42 = R81
R43 = R82

jr

No change. Should have just done C48 while I was in there. I'll change out C48 and check those two resistors next. I'll get this yet :)

Changed C48. R81 (R42) was at 52K, R82 (R43) was at 73K. Put in brand new 39K 1 watt 5% resistors. No change in the picture.

Did your supply voltages ever come down closer to spec? What DC voltage do you read now on pins 4-6 of V13B(horz osc)?

And if the voltages are *still* too high, perhaps use your variac to reduce until they are normal and see how the horiz behaves.

Is 10 k resistor from horiz hold to the transformer ok? How about the 50 uuf cap to the sync circuit? Does the "parts set" have a good horizontal transformer if you need it?

jr

Did your supply voltages ever come down closer to spec? What DC voltage do you read now on pins 4-6 of V13B(horz osc)?

-69 VDC on pin 4, 2.44 VDC on pin 6. Still high.

And if the voltages are *still* too high, perhaps use your variac to reduce until they are normal and see how the horiz behaves.

Is 10 k resistor from horiz hold to the transformer ok? How about the 50 uuf cap to the sync circuit? Does the "parts set" have a good horizontal transformer if you need it?

jr

Tried it on the variac, and the only thing that happened is that the picture shrunk, and it shrunk as it was, it didn't come into sync.

I'll check the 10K resistor next. Everything on the parts set (except for the frozen controls) *looks* okay? But I haven't tested anything.

Resistor reads just under 12K. Enough to cause what I'm facing? Might as well replace it while I'm in here.

Tried it on the variac, and the only thing that happened is that the picture shrunk, and it shrunk as it was, it didn't come into sync.


Darn... that actually worked on my 7" Philco... thing made a decent but small picture at about 90 volts line... I found some parts way out of spec!

jr

12K does not seem to be too far off, does the pot have it's full range of 20K?

Resistor reads just under 12K. Enough to cause what I'm facing? Might as well replace it while I'm in here.
Which direction are you turning the hold control when it's going 'toward' good sync? Is it the maximum-resistance or minimum-resistance direction?

Pot smoothly ranges to 15K. I tested it in-circuit. Seems about midrange where the sync locks in to where it's shown in the video.

Changing the 10K resistor made no difference, but at least when it's done, the horizontal is going to be REALLY stable :)

Man, THIS has 'un really got you Buffaloed..No pun intended, either..

Heh :D

It's snowing out like crazy, the wife was working most of the night, my Mouser order for DuMont and Halolite parts didn't show, so I had nothing else to do anyway. Besides which, this is extremely valuable experience that I'm getting :)

This l'il guy's a 7", correct ? Never understood how those worked, anyway... They look like they're missin' about half the parts..

What did you measure on pin 5 of V13B?

Maybe it's time to ohm out T2. Sams says 50 ohms primary, 150 ohms secondary. Interestingly Sams shows the same part number used for both horizontal and vertical blocking oscillator transforms(T2,T3). That makes it easy to compare windings.

Any chance there's an adjustable core down inside the top hole of T2? Sams doesn't mention it, but I just noticed the hole in the Sams top of chassis photo.

Pot smoothly ranges to 15K. I tested it in-circuit.

15K *not* 20K? My Sams sez it should be 20K... In-circuit measurement should not make any difference, as it appears that the pot is isolated DC wise from any shunting paths. What does the pot in the "parts set" measure?

jr

Any chance there's an adjustable core down inside the top hole of T2? Sams doesn't mention it, but I just noticed the hole in the Sams top of chassis photo.

Nah, no such luck. I'll ohm that out next.

One thing I should note. It looks like T4 was replaced at some point in time with something that was a little larger than the original. I decided to ohm that out first. Should be 250 ohms on the primary, and 200 on the secondary. I've got 225 on the primary and 190 on the secondary. Dunno if that could be a contributing factor.

15K *not* 20K? My Sams sez it should be 20K... In-circuit measurement should not make any difference, as it appears that the pot is isolated DC wise from any shunting paths. What does the pot in the "parts set" measure?

jr

I'm getting 16K on the pot on the parts set.

What did you measure on pin 5 of V13B?

Maybe it's time to ohm out T2. Sams says 50 ohms primary, 150 ohms secondary. Interestingly Sams shows the same part number used for both horizontal and vertical blocking oscillator transforms(T2,T3). That makes it easy to compare windings.

I'm getting 44 and 142 out of T2. This one I tested in circuit, which I don't usually do. It's just a PITA getting in there to unhook a side, but I will if I gotta :)

Going on the assumption that the H frequency is too high (rather than too low), you could experiment with slowing it down by subbing a couple of values.
The 10K resistor.. try something like 15K, 18K, or 22K
The .01 cap.. increase value by adding something like .002, .0033, or .0047 across it.

If this improves things, while not "fixing" it, it'd at least tell you it's moving the frequency in the right direction (ie., down).

Is it safe to assume we don't have a scope at the scene of this repair?

This set is certainly being a little stinker. :yes:

I have a Hickok 505A scope, but I don't think it's up to par yet. I threw some caps in it a few months back, but never finished the job because I was informed that this scope was useless without external sweep and RF generators.

Going on the assumption that the H frequency is too high (rather than too low), you could experiment with slowing it down by subbing a couple of values.
The 10K resistor.. try something like 15K, 18K, or 22K
The .01 cap.. increase value by adding something like .002, .0033, or .0047 across it.

If this improves things, while not "fixing" it, it'd at least tell you it's moving the frequency in the right direction (ie., down).

I subbed in a 20 K resistor. No change.

I added .0047 across the .01 cap. No change.

Man, this is really a tough dog. Should I start scouring Craigslist for a scope?

I'm getting 44 and 142 out of T2. This one I tested in circuit, which I don't usually do. It's just a PITA getting in there to unhook a side, but I will if I gotta :)

In-circuit measurement *should* be ok... I don't see an obvious DC path that would affect the reading other than the two 39K resistors, which would only slightly lower the readings. What does the vertical transformer measure? How about the transformers in the "parts set"?

jr

Decided to swap the horizontal sweep transformer out of the parts set, and looky what I got!!!!

Obviously, it's not done, but I'm a HECK of a lost closer than I was! :banana:

Now the weird part was that the readings on the transformer that was in the set weren't far off spec, but it was some replacement that was larger than the original. I figured that maybe it was wound different or something, causing the issue. Bingo!!!

Now, to fix the vertical issue and the lousy focus. At least it's nice to end tonight on a win....sort of :)

Glad you got it working. :thmbsp:

Oh, and you should have another backup in the spare vertical osc transformer. At least Sams calls them the same part number, which seems a little weird.

Good thing you made mention of that. I tested and replaced 3 of the resistors in the focus circuit, one of the 2.2 M was open. Powered up the set, no raster, and the transformer I just installed was starting to brown up. In all fairness, that transformer that I installed looked like dried out garbage, but it ohmed out fine.

Guess that's next on the list.

Checked the transformer. Now I see why there was black tape on the one I removed.....seems that something happened to this transformer when I went to relocate the chassis ground (it was clip leaded for the test). Move the wire one way, open. Move it another, it's in spec, move it another, and it's WAY high.

Yep, transformer time.

New transformer installed, and with the resistors I replaced, she's making a pretty nice picture. Sound is good too :)

The only thing that I have to address is the vertical height. Not ideal, but may not be noticeable once in the cabinet. Still, going to check all the resistors in the circuit to see where we're at. Of course, I still have to tweak the linearity, but I'm pretty pleased so far!

Pretty pretty pretty!

Here's a video of where we're at now. I replaced a 10M and a 100K resistor that were about 30% high. Pulled in the picture somewhat better:

http://www.youtube.com/watch?v=r0MsL64FJeo&feature=youtu.be

Still as you can tell, it's got slightly insufficient height. I had to adjust the linearity to compensate for it to get (close to) a full raster. The 6SL7 tests like new. I figure this is some type of low emission in the vertical output circuit, and the only component I can think of in there that I haven't changed or tested is a 100 PF cap.

Or am I being too picky? :dunno:

Or am I being too picky? :dunno:

You should be able to get the picture more linear than that... Are the voltages ok? Do you have other 6SN7s and 6SL7s to swap? (sometimes a tube test does not tell the whole story).... Once, in one of these sets I mixed up the 6SN7 and 6SL7 and the set worked *almost* ok, but had height problems.

jr

I admit that right now with the set working somewhat decently, I'm starting to get lazy, and I don't wanna go back and test voltages :D . No other way though.

I have a boatload of 6SN7s, I should have some 6SL7s here too. I'll take time to do that tomorrow....I noticed that the horizontal width control has a flat spot big enough to drive a car through, and the flat spot is right where it should be, so I'll test the one out of the parts set and swap it over.

New weird issue with the Admiral, after about 6 hours of use. Getting intermittent blanking of the horizontal sweep. Linearity's not perfect I know, but here's a video. I'm almost thinking that the used horizontal sweep transformer that I installed is starting to give way.

http://www.youtube.com/watch?v=wWhXOKf5BIs&feature=youtu.be

To follow up, for the first 20 minutes the set is on, this blanking is not evident.

Seems to start after the set has been on for about 20 minutes.

I would also check the video, perhaps there is a noisy resistor in the video amp. Perhaps check for HV arcing as well? IMHO, the horizontal is looking nice and stable.
jr

Look closely at the blanking. It almost looks like the scan lines are getting folded together.....for lack of better phraseology.....

So there are little "step function" jumps in the vertical position as the tube is scanned? Noisy resistors? Dirty vertical position pot?
jr

I replaced almost all of the resistors in the vertical section, but there were a couple that I had to rob out of the parts chassis because I didn't have suitable replacements. Hm.

Other than testing the resistor to see if it's in spec, how does one spot a "noisy" resistor?

Look closely at the blanking. It almost looks like the scan lines are getting folded together.....for lack of better phraseology.....

That description almost makes me think line pairing. Does it look like every other scan line is missing when this happens? I can't really detect what you're describing from watching the video.

Other than testing the resistor to see if it's in spec, how does one spot a "noisy" resistor?

Since the problem occurs after the set is "warmed up", perhaps blasting suspect components with "circuit cool" might reveal the source of the problem.
jr

Often some judicious poking and prodding (with an insulated tool), tapping tubes (including the CRT neck) will reveal an intermittent component.
Freez Spray ("circuit cooler") can be useful if the condition is heat related.

The set's now in the hands of my friend Al, in MD. It's generally been performing well for him, other than that intermittent raster issue.

Since Al is pretty handy and not a stranger to the soldering iron (and loves this stuff), I suggested that he replace the remaining resistors in the sweep circuits.

I probably would have, but ran out of time......he was in to visit family for Christmas :)

Resistors ordered.

ID, Snip, solder. Repeat! :D