There's something confusing about the SAMS schematic that Kevin Keuhn attached in post 192. We all know that dashed lines on a SAMS means an alternative circuit that may have come about on a later chassis.

Look at C3D. The alternate circuit has the positive side of C3D connected to R54. However, it also shows that the negative side of C3D is connected to +245V. That is definitely an error as C3 is a four section electrolytic with a common ground. Since C3A-C are all in the power supply, their negative sides all go to ground.

What gives? SAMS error?

There's something confusing about the SAMS schematic that Kevin Keuhn attached in post 192. We all know that dashed lines on a SAMS means an alternative circuit that may have come about on a later chassis.

Look at C3D. The alternate circuit has the positive side of C3D connected to R54. However, it also shows that the negative side of C3D is connected to +245V. That is definitely an error as C3 is a four section electrolytic with a common ground. Since C3A-C are all in the power supply, their negative sides all go to ground.

What gives? SAMS error?

What my hard copy of the Sam's for this TV shows is that C3A-C3C are in one can and C3D is a separate non-polarized cap in some models in a small note on the bottom of the schematic which is what that is all about.

I hope that helps you out.

What my hard copy of the Sam's for this TV shows is that C3A-C3C are in one can and C3D is a separate non-polarized cap in some models in a small note on the bottom of the schematic which is what that is all about.

I hope that helps you out.

Yes and the alternate circuit has C3D negative lead going to B+ and the positive to B Boost, so it's still polarized correctly for that scenario. I suspect they did it that way so that full B boost voltage wasn't across C3D, because B Boost likely swings above 500v during warmup. Off hand I have no idea why they went to a non polarized cap unless it's exposed to negative going spikes on the B Boost. If by chance you used a 450v cap for C3D it could become unhappy with full B Boost across it. :scratch2:

Yes and the alternate circuit has C3D negative lead going to B+ and the positive to B Boost, so it's still polarized correctly for that scenario. I suspect they did it that way so that full B boost voltage wasn't across C3D, because B Boost likely swings above 500v during warmup. Off hand I have no idea why they went to a non polarized cap unless it's exposed to negative going spikes on the B Boost. If by chance you used a 450v cap for C3D it could become unhappy with full B Boost across it. :scratch2:

Yes I did use a 450V cap there, but it is rated for 550V surge so it should be fine.

OK, I checked all of my negative lead connections on my electrolytics and they aren't floating, so that's not the problem.

But I think I definitely figured out this time for sure where my voltage is getting lost at on my Zenith Bugeye TV.

C49, a 470pF ceramic disc capacitor that goes from TS8-4 to chassis ground measures open (measuring the resistance across it, it quickly goes to O. L. from 25 MOhm and measuring it on my cap checker it measures 25pF, and when I measured the voltages across that cap my voltages were right there going to ground.

So am I onto something here? :scratch2:

Are you measuring C49 out of circuit? And even if C49 were open it would have no influence on the weird B+ voltages you're reporting. I'd say it's nothing more than a RF filter to the audio signal leaving the detector plate.

Next definitely for sure possibility please. ;)

Are you measuring C49 out of circuit? And even if C49 were open it would have no influence on the weird B+ voltages you're reporting. I'd say it's nothing more than a RF filter to the audio signal leaving the detector plate.

Next definitely for sure possibility please. ;)

Well that capacitor though is where my voltages to the audio output circuit are getting lost though for sure because I measured the B+ voltage from the terminal that C49 ties to and goes to ground and I have B+ voltage there going to ground but then when I measure from that point to the other side of C50 the 10,000 pF ceramic disc cap there's no voltage there (it's -20V or so) and that is supposed to supply the voltages to pins 5 and 6 of the 6AQ5 tube, and yes I did replace C50 with a new capacitor finally and that didn't change the voltage readings any.

Yes I did use a 450V cap there, but it is rated for 550V surge so it should be fine.

It wouldn't be a bad idea to measure your B Boost directly across that cap. My Bugeye's B Boost runs around 475v with it's decrepit selenium rectifiers still in it and 117 AC line voltage.

Well that capacitor though is where my voltages to the audio output circuit are getting lost though for sure because I measured the B+ voltage from the terminal that C49 ties to and goes to ground and I have B+ voltage there going to ground but then when I measure from that point to the other side of C50 the 10,000 pF ceramic disc cap there's no voltage there (it's -20V or so) and that is supposed to supply the voltages to pins 5 and 6 of the 6AQ5 tube, and yes I did replace C50 with a new capacitor finally and that didn't change the voltage readings any.

Let's get one thing straight here. B+ is not suppose to get to pins 5 and 6 of the 6AQ5 through C50. C50 is a audio signal coupling cap to the top of the volume control. C50's function is to pass the audio signal from the plate of the detector to the audio output grid. A capacitor is used because it's intended to block the B+ feeding the plate of the detector tube from getting into the grid circuit of the 6AQ5.

It wouldn't be a bad idea to measure your B Boost directly across that cap. My Bugeye's B Boost runs around 475v with it's decrepit selenium rectifiers still in it and 117 AC line voltage.

Ok, and would replacing those old selenium rectifiers with a couple of 1N4007 diodes be a suitable replacement? If so do I need to add or change some voltage dropping resistors in the circuit?

Let's get one thing straight here. B+ is not suppose to get to pins 5 and 6 of the 6AQ5 through C50. C50 is a audio signal coupling cap to the top of the volume control. C50's function is to pass the audio signal from the plate of the detector to the audio output grid. A capacitor is used because it's intended to block the B+ feeding the plate of the detector tube from getting into the grid circuit of the 6AQ5.

Well either way I'm not getting any audio out of the TV and I'm still not getting the 200+ volts I need to be getting on pins 5 and 6 of the 6AQ5 tube that the Sam's calls out and I'm not getting 17V on pin 2 of the 6AQ5 either, so I'm still stumped as to what's going on with the audio section of this TV, and I've still got no signal from the tuner to the TV on here either.

Well either way I'm not getting any audio out of the TV and I'm still not getting the 200+ volts I need to be getting on pins 5 and 6 of the 6AQ5 tube that the Sam's calls out and I'm not getting 17V on pin 2 of the 6AQ5 either, so I'm still stumped as to what's going on with the audio section of this TV, and I've still got no signal from the tuner to the TV on here either.


Reread post #245 where you had 210v at C3B. You need to follow that point to pins 5 and 6 of your 6AQ5 and see where you loose the 210V. Follow the schematic and ohm everything out. One path is from C3B positive to pin 6(screen), the other is C3B positive to the bottom(red) wire of the output transformer primary. B+ needs to go in on the red wire of the primary winding and exit on the blue wire to pin 5(plate) of the 6AQ5. If there's no connections where there should be, something has become open or otherwise mis-wired.


OK. That's close enough for now. At least you've verified B+ on C3b.

The identical voltage should be appearing on pin 6 (screen grid) of the 5AQ5, and on the bottom of the output xfmr primary (red lead).

In other words, there should be solid continuity (zero ohms) twixt all those points. (Forget the negative voltage issue for now) Main thing is to find out what connection's gone open.

With the set OFF, and an ohmmeter set to RX1, connect the black lead to pin 6. With the other lead, check for zero ohms to bottom of xfmr primary (red lead), and to C3b. You'll probably find the connection to C3b is what's open.

BTW, also check the xfmr primary for a few hundred ohms between pins 6 and 5 (plate) of the 5AQ5.

Once this is all sorted out, check for solid continuity (zero ohms) from C3's can to ground. Any resistance here could be contributing to the 'negative voltage' condition.

[Edit] Here's a picture of the bottom side of my working chassis showing the 5AQ5(6AQ5) connections so you can compare your wiring.

https://live.staticflickr.com/65535/51770764018_b2c916bd1c_c.jpg

Reread post #245 where you had 210v at C3B. You need to follow that point to pins 5 and 6 of your 6AQ5 and see where you loose the 210V. Follow the schematic and ohm everything out. One path is from C3B positive to pin 6(screen), the other is C3B positive to the bottom(red) wire of the output transformer primary. B+ needs to go in on the red wire of the primary winding and exit on the blue wire to pin 5(plate) of the 6AQ5. If there's no connections where there should be, something has become open or otherwise mis-wired.




[Edit] Here's a picture of the bottom side of my working chassis showing the 5AQ5(6AQ5) connections so you can compare your wiring.

https://live.staticflickr.com/65535/51770764018_b2c916bd1c_c.jpg

Well besides the fact that your TV's wiring is in much better shape than mine is (the color is faded from my TV's wiring) I don't see anything different from yours and mine except that it seems you still kept some of the original can caps in circuit whereas mine are all replacent capacitors.

I really don't know what's going here.

Well besides the fact that your TV's wiring is in much better shape than mine is (the color is faded from my TV's wiring) I don't see anything different from yours and mine except that it seems you still kept some of the original can caps in circuit whereas mine are all replacent capacitors.

I really don't know what's going here.

I sawed the top off my cans and re-used the old terminals. Any chance you can post a close up of the underside of your chassis around the 6AQ5, including your filter caps? Sometimes it helps to have a fresh set of eye's look things over.

https://live.staticflickr.com/65535/51770707506_2118b79dbe_c.jpg

I sawed the top off my cans and re-used the old terminals. Any chance you can post a close up of the underside of your chassis around the 6AQ5, including your filter caps? Sometimes it helps to have a fresh set of eye's look things over.

https://live.staticflickr.com/65535/51770707506_2118b79dbe_c.jpg

Ok, I wondered about that. I'll get you a picture of my 5 (6)AQ5 tube section of the TV and the replacement electrolytics.

I'll have to do it when I get home from work because I'm at work right now. I meant to include this in my initial post but forgot to, I'm adding it as an additional posting because I know you don't like it when I edit my posts multiple times to add additional information.

OK so here's some pictures of the Audio Section of my Zenith Bugeye TV, and of all of the Electrolytic caps I replaced in the TV.

I added some visual markers and texts to each of the photos so you can tell what's what in each photo.

See pictures below.

OK so here's some pictures of the Audio Section of my Zenith Bugeye TV, and of all of the Electrolytic caps I replaced in the TV.

I added some visual markers and texts to each of the photos so you can tell what's what in each photo.

See pictures below.

I think I see a problem but it's tough to see everything in your photo. Take a look at my orange circled area's. All 3 circled points should be interconnected. Inside the largest circle there should be 4 items soldered together. The + side of C3B, the right lead from R56(470 ohm feed from B+), left lead of R54(390k), and a orange wire should head over to the second solder pocket from the right end of the terminal strip directly below the 6AQ5 socket. From that same solder pocket another orange wire should be connected to pin 6 of the 6/5AQ5, and also the red lead from the audio output transformer should be soldered into that same pocket. But specifically I can't see any wire coming over to that solder pocket from the positive end of C3B(large circled point)? You can reference the photo from my set. In any event that's the path B+ needs to follow to get from C3B over to the audio output tube.

https://live.staticflickr.com/65535/51772664773_40edda1f7c_c.jpg

https://live.staticflickr.com/65535/51772492631_d8b2e87f0b_c.jpg

I sawed the top off my cans and re-used the old terminals. Any chance you can post a close up of the underside of your chassis around the 6AQ5, including your filter caps? Sometimes it helps to have a fresh set of eye's look things over.

https://live.staticflickr.com/65535/51770707506_2118b79dbe_c.jpg
Rather impressive! How do you cut the cans so perfect? :thmbsp:
Bought and sold a set like that about 60 years ago. Mine was an earlier model that used a 3BY6 instead of the better circuit using a 3BU8.
The outward appearance was similar.

Rather impressive! How do you cut the cans so perfect? :thmbsp:
Bought and sold a set like that about 60 years ago. Mine was an earlier model that used a 3BY6 instead of the better circuit using a 3BU8.
The outward appearance was similar.

Thanks. I actually removed these and used my band saw. Then a few passes over 220 grit on a flat surface squares the end. Seems like a lot of work, but by using a very large (radiator sized :D) soldering iron I'm able to heat the ground lugs and squeeze them straight with a flat nose pliers, then carefully wiggle them free. Space permitting you certainly could hack them off using a Zona saw while they're still attached to a chassis.

Thanks. I actually removed these and used my band saw. Then a few passes over 220 grit on a flat surface squares the end. Seems like a lot of work, but by using a very large (radiator sized :D) soldering iron I'm able to heat the ground lugs and squeeze them straight with a flat nose pliers, then carefully wiggle them free. Space permitting you certainly could hack them off using a Zona saw while they're still attached to a chassis.

OK, so I looked over my chassis after you mentioned the missing wire and sure enough, I'm not sure how I missed it but I forgot to put that wire back in when I removed it from the old can cap to install the new one, I now have the voltages back in the audio section, and its functioning as it should. :thmbsp:

But now I have a new problem, one of my Video IF tubes was bad (which is why I'm not getting anything from the tuner) which is a 3CB6 and I tried subbing in a 6CB6 (because I have a whole butt load of them) and it seems the TV doesn't like them, because they just glow white and then just die after 3 seconds (and it doesn't matter which 3CB6 socket its stuck in, it does the same thing in all 3 sockets) and I was hoping I could get away with not having to order a new tube for the TV (as I don't have any 3CB6 tubes in my stash.)

Is it normal for a 6.3V Tube to glow white hot and then burn out after 3 seconds in a socket originally meant for a 3V tube in a series string set?
I was thinking that it was possible to install a higher voltage tube in a lower voltage tube spot in series string radios and TVs (like how you can sub in place of a 35L6 a 50L6 on old Series string radios and it would run fine.)

Am I missing something here? :scratch2:

It's a series strung set and the current ratings for a 3CB6 are double a 6CB6. 0.6A vs 0.3A.

The 35L6 and 50L6 are both 0.15A filament tubes.

It's a series strung set and the current ratings for a 3CB6 are double a 6CB6. 0.6A vs 0.3A.

The 35L6 and 50L6 are both 0.15A filament tubes.

Ok, so I'm guessing that the reason why the 6AQ5 worked in place of a 5AQ5 was because the current draw was similar on those tubes? :scratch2:

So then with that in mind I will probably have to order another 3CB6 after all. :sigh:

OK, so I looked over my chassis after you mentioned the missing wire and sure enough, I'm not sure how I missed it but I forgot to put that wire back in when I removed it from the old can cap to install the new one, I now have the voltages back in the audio section, and its functioning as it should. :thmbsp:

But now I have a new problem, one of my Video IF tubes was bad (which is why I'm not getting anything from the tuner) which is a 3CB6 and I tried subbing in a 6CB6 (because I have a whole butt load of them) and it seems the TV doesn't like them, because they just glow white and then just die after 3 seconds (and it doesn't matter which 3CB6 socket its stuck in, it does the same thing in all 3 sockets) and I was hoping I could get away with not having to order a new tube for the TV (as I don't have any 3CB6 tubes in my stash.)

Is it normal for a 6.3V Tube to glow white hot and then burn out after 3 seconds in a socket originally meant for a 3V tube in a series string set?
I was thinking that it was possible to install a higher voltage tube in a lower voltage tube spot in series string radios and TVs (like how you can sub in place of a 35L6 a 50L6 on old Series string radios and it would run fine.)

Am I missing something here? :scratch2:

3CB6 is 600ma filament vs 6CB6 300ma. In other words your entire series string of tubes should be 600ma type, so trying to pull 600ma through a filament intended for 300ma isn't going to cut it. Your 6AQ5 is a 450ma tube, so you're really pushing that one as well.

Congratulations on a major victory putting that missing B+ wire back in place. :D Although I can't believe how much time we've been chasing tail because of that very simple oversight. :nono: You really need to post more photo's of your handiwork when asking for advise. My suggestion to you is to take very detailed pictures before you remove any original components so you can refer back to them. And you would do us all a big favor by getting a couple books on understanding very basic DC circuits so you have a better grasp of how to trace voltages in a power supply circuit. Read up on Ohms Law and understand how to apply it.

Is it normal for a 6.3V Tube to glow white hot and then burn out after 3 seconds in a socket originally meant for a 3V tube in a series string set?

Yes.

A little factoid worth bookmarking:

A series circuit is constant current thru the whole string.

A parallel circuit is constant voltage across the whole (i.e., the voltage across each component is the same, tho each may draw different current).

I was thinking that it was possible to install a higher voltage tube in a lower voltage tube spot in series string radios and TVs

A higher-voltage rated heater has higher resistance, thus runs hotter in the constant-current string (that's why the 6CB6's heater was actually seeing closer to 12 volts and blew its cookies).

(like how you can sub in place of a 35L6 a 50L6 on old Series string radios and it would run fine.)

Am I missing something here? :scratch2:

The 35 and 50 volt heaters are both designed for the same current (.15 A).

“ Your 6AQ5 is a 450ma tube, so you're really pushing that one as well. “

For grins, I connected a 6AQ5 to a constant current power supply set to 600ma and measured the voltage drop across the heater. The heater voltage stabilized at about 10.5 volts! This is indeed really pushing it for a 6.3 volt tube... I suggest that proper 5AQ5 be ordered as well.

jr

“ Your 6AQ5 is a 450ma tube, so you're really pushing that one as well. “

For grins, I connected a 6AQ5 to a constant current power supply set to 600ma and measured the voltage drop across the heater. The heater voltage stabilized at about 10.5 volts! This is indeed really pushing it for a 6.3 volt tube... I suggest that proper 5AQ5 be ordered as well.

jr

Ok, I'll have to get the proper tubes ordered I guess. Hopefully they aren't going to be too expensive.

“ Your 6AQ5 is a 450ma tube, so you're really pushing that one as well. “

For grins, I connected a 6AQ5 to a constant current power supply set to 600ma and measured the voltage drop across the heater. The heater voltage stabilized at about 10.5 volts! This is indeed really pushing it for a 6.3 volt tube... I suggest that proper 5AQ5 be ordered as well.

jr

OK well I also noticed that the previous owner of this TV had installed a 6BU8 in place of a 3BU8 tube in the TV I'm guessing that should also be replaced with the proper tube as well?

OK well I also noticed that the previous owner of this TV had installed a 6BU8 in place of a 3BU8 tube in the TV I'm guessing that should also be replaced with the proper tube as well?
First, you might want to see if someone's put a shunt resistor across the 3BU8 heater (pins 4 and 5). It'd be a low value resistor, something like 20 ohms. Without the shunt for protection, seems like the 6BU8 would be lighting up like that 6CB6 did.

Ok, I'll have to get the proper tubes ordered I guess. Hopefully they aren't going to be too expensive.

Those series string tubes are usually quite cheap. If you shop around $3 more or less. Especially the IF tubes.

X2 at what everyone said abot taking pictures beforehand. Saves a lot of headaches. It sure beats the old days of writing notes down on paper.

OK, so the tube in the TV that I thought was a 6BU8 was actually a 3BU8 tube it was a GE branded replacement tube dated 39th Week of 1963, there was a bunch of dirt buildup on the tube designation number and the way GE does their tube numers in a "stencil" font the dirt buildup made the 3 look like a 6.

And then as far as the 5AQ5 goes, I took it and rechecked it in another tube checker I had laying around (a B & K DynaJet Model 666/606 Tube Tester) and the tube checked fine (no shorts in it anymore) so I wonder if I somehow blew off whatever was causing the short in the tube, I know that can happen sometimes.

So it looks like all I need is that 3CB6 tube and a 6CN7 tube which I don't happen to have in my stash anywhere, the 6CN7 tube in the TV which is an original Zenith badged GE tube dated the 20th Week of 1956 only had one section that tested good, the other 2 sections tested completely dead.

First, you might want to see if someone's put a shunt resistor across the 3BU8 heater (pins 4 and 5). It'd be a low value resistor, something like 20 ohms. Without the shunt for protection, seems like the 6BU8 would be lighting up like that 6CB6 did.

It was a 3BU8 after all, the way the dirt and grime buildup was on the tube it made the 3 look like a 6.

OK, so the tube in the TV that I thought was a 6BU8 was actually a 3BU8 tube it was a GE branded replacement tube dated 39th Week of 1963, there was a bunch of dirt buildup on the tube designation number and the way GE does their tube numers in a "stencil" font the dirt buildup made the 3 look like a 6.

And then as far as the 5AQ5 goes, I took it and rechecked it in another tube checker I had laying around (a B & K DynaJet Model 666/606 Tube Tester) and the tube checked fine (no shorts in it anymore) so I wonder if I somehow blew off whatever was causing the short in the tube, I know that can happen sometimes.

So it looks like all I need is that 3CB6 tube and a 6CN7 tube which I don't happen to have in my stash anywhere, the 6CN7 tube in the TV which is an original Zenith badged GE tube dated the 20th Week of 1956 only had one section that tested good, the other 2 sections tested completely dead.

Although I've never used them findatube.com is looking like a reasonable place for common TV tubes. 3CB6-$2.50, 6CN7-$3.00. And only a state away from you?

Although I've never used them findatube.com is looking like a reasonable place for common TV tubes. 3CB6-$2.50, 6CN7-$3.00. And only a state away from you?

OK, I'll give them a try. :scratch2:

So if the Horizontal AFC/Horizontal Phase Detector Tube is bad would that cause issues with the TV not receiving/dsiplaying signals from the tuner properly or would that be the Video IF tubes that would cause that?

OK so I sent Bob over at Find A Tube a message with the tubes I'm looking for and hopefully I'll hear back from him on Monday or sometime after that (since its Christmas this weekend.)

He actually got back to me right away. It would only be $6 to ship to me he said. :thmbsp:

A little update:

Still waiting on the tubes that I ordered for my Zenith "Bugeye" TV that I had ordered around Christmas and were supposedly shipped the monday after Christmas, and here it is the middle of the first week of January and I still haven't gotten my tubes yet. :sigh::thumbsdn:

The more you need a part, the slower the shipping is.

Well my parts came in today and I got the TV working, mostly, I'm still having some issues with the centering of the picture and the Video and Audio IF are still a little off yet, so I'm still trying to get that adjusted but other than that it is producing a picture from the tuner and some audio but its not very loud audio and the Video IF is still a little off, hopefully when I get that B & K 1070 TV Analyst (which is supposed to come tomorrow) maybe that will help with getting the video and audio IF finalized on the TV.

Also how do you tell which station this TV is on? There doesn't seem to be pointer or anything that points to what the channel selector knob is on on this TV.

On my Bugeye the selected channel is at the 12 o'clock position. Unfortunately the Analyst isn't an alignment tool, It's basically a substitution signal source for trouble shooting the various circuits in a TV, say if you can't get a signal through via the tuner, you can inject directly into the video IF, or video amp to see where the signal is lost . The best way to check alignment is with a sweep generator and oscilloscope to look at the video IF response curve.

On my Bugeye the selected channel is at the 12 o'clock position. Unfortunately the Analyst isn't an alignment tool, It's basically a substitution signal source for trouble shooting the various circuits in a TV, say if you can't get a signal through via the tuner, you can inject directly into the video IF, or video amp to see where the signal is lost . The best way to check alignment is with a sweep generator and oscilloscope to look at the video IF response curve.

Oh, ok. Well anyways I know the IF is definitely off on this TV (just like it was on my Meck TV) also how do you adjust the centering rings for a properly centered picture?
I tried adjusting the centering rings on my TV and just about got it centered and then I whacked my hand against something on the picture tube and got a nice jolt off of it.
On mine I noticed that when I would adjust the height and linearity adjustments the screen would go really dark especially towards the top and also something seems to be off with the DC Restoration on this TV because the screen is really dark especially when going through the channels the screen will just go black and then when you settle on a channel then the screen will finally brighten up after about 10 seconds.
Is this normal?

As for the 23" Zenith I got some new bulbs ordered for the tuner and they came in the mail today as well, and unfortunately the lights for the tuner don't seem to trigger on and off correctly because when I have the tuner triggered for the VHF tuner the pilot light doesn't kick on right away and also when the UHF tuner is triggered the pilot light doesn't always turn on for that either.

Also the TV isn't producing a signal for the tuner and I figured out that the Oscillator/Mixer Tube (a 6GJ7 tube) iin the VHF tuner is pretty much dead (which was also what was wrong with the bugeye TV as well) unfortunately I don't have a 6GJ7 tube in my tube stash, nor any of its substitutes.

Oh, ok. Well anyways I know the IF is definitely off on this TV (just like it was on my Meck TV) also how do you adjust the centering rings for a properly centered picture?
I tried adjusting the centering rings on my TV and just about got it centered and then I whacked my hand against something on the picture tube and got a nice jolt off of it.
On mine I noticed that when I would adjust the height and linearity adjustments the screen would go really dark especially towards the top and also something seems to be off with the DC Restoration on this TV because the screen is really dark especially when going through the channels the screen will just go black and then when you settle on a channel then the screen will finally brighten up after about 10 seconds.
Is this normal?


Please don't mess with the IF adjustments.

Centering consists of spreading or bringing closer the 2 circular rings along with moving them together. Fiddling with them should give you an indication of the direction you need to go.

There is no DC restoration.

You should be able to get a full snowy white raster with no signal going to the tuner. Your brightness control should be able to take it from bright to complete darkness.

On mine I found the cathode bypass cap(C2) on the 6CM7 vertical output tube really needs to be at least 60uf in order to get decent vertical linearity. I tried a 47uf and that was a no go.

Please don't mess with the IF adjustments.

Centering consists of spreading or bringing closer the 2 circular rings along with moving them together. Fiddling with them should give you an indication of the direction you need to go.

There is no DC restoration.

You should be able to get a full snowy white raster with no signal going to the tuner. Your brightness control should be able to take it from bright to complete darkness.

On mine I found the cathode bypass cap(C2) on the 6CM7 vertical output tube really needs to be at least 60uf in order to get decent vertical linearity. I tried a 47uf and that was a no go.

Well on mine the IF Adjustments were already fiddled with, that was part of the reason why my tuner wasn't working right, besides bad tubes.

As far as the full bright snowy raster goes that is a no go, the top part of the screen is completely dark, and trying to adjust the centering rings doesn't affect it any, there is supposed to be a ion trap on this TV but I don't know where it is in reference to the rest of the picture tube, the Sams shows it as being part of the yoke but I don't see anything on the yoke assembly that looks like an ion trap.

Any ideas?

As far as the full bright snowy raster goes that is a no go, the top part of the screen is completely dark, and trying to adjust the centering rings doesn't affect it any, there is supposed to be a ion trap on this TV but I don't know where it is in reference to the rest of the picture tube, the Sams shows it as being part of the yoke but I don't see anything on the yoke assembly that looks like an ion trap.

Any ideas?

Ion trap should be out on base end of the neck where most are. What Sams shows is the schematic representation, not physical location. Are you currently running without the ion trap?

Also both of my sets have a width sleeve - a thin piece of brass sheet wrapped around the neck inside the yoke. Moving that in and out of the yoke varies the picture width.

Ion trap should be out on base end of the neck where most are. What Sams shows is the schematic representation, not physical location. Are you currently running without the ion trap?

Also both of my sets have a width sleeve - a thin piece of brass sheet wrapped around the neck inside the yoke. Moving that in and out of the yoke varies the picture width.

Well there is an ion trap looking thing on the end of the neck near the base on my CRT but it I try to rotate it or pull it in or out and it wont budge like its stuck or something like that.

And with the base of the CRT already being somewhat damaged I don't want to force anything and risk damaging the CRT any further.

I have a picture posted below showing what I mean.

Also my TV Analyst Came today, and its intact, but I have no idea if it functions or not because I don't have any cables for it yet. I would guess that the probes for this thing could still be bought seeing as B & K is still around and they still make test equipment and probes for them.

Well there is an ion trap looking thing on the end of the neck near the base on my CRT but it I try to rotate it or pull it in or out and it wont budge like its stuck or something like that.

And with the base of the CRT already being somewhat damaged I don't want to force anything and risk damaging the CRT any further.

I have a picture posted below showing what I mean.

Also my TV Analyst Came today, and its intact, but I have no idea if it functions or not because I don't have any cables for it yet. I would guess that the probes for this thing could still be bought seeing as B & K is still around and they still make test equipment and probes for them.
The ion trap is the thing with the spring. Remove the spring and the trap should move.
That set was stored in a damp environment, as it shows mildew all over.

Good to hear the B&K showed up. The only cables you need are a shielded 50 ohm BNC cable to alligator clip leads and a couple un-sheilded male pin plugs to alligators clip leads. Those pin connectors are the same as what commonly came with inexpensive VOM meters back in the day. Nothing special about them and I'd be shocked if you don't already have the BNC cable with all the test gear you've told us about. ;)

But before worrying about connecting any signal to the Bugeye, get your CRT sorted out. You don't need any video signal to get a raster.

When I first got mine I used a BNC scope probe before making a dedicated BNC to clip lead cable...It worked fine with both.

Good to hear the B&K showed up. The only cables you need are a shielded 50 ohm BNC cable to alligator clip leads and a couple un-sheilded male pin plugs to alligators clip leads. Those pin connectors are the same as what commonly came with inexpensive VOM meters back in the day. Nothing special about them and I'd be shocked if you don't already have the BNC cable with all the test gear you've told us about. ;)

But before worrying about connecting any signal to the Bugeye, get your CRT sorted out. You don't need any video signal to get a raster.

I got the TV to give a proper raster but now I've hooked up the TV Analyst to the TV through the Video IF input and it showed the test pattern like it was supposed to but the linearity is way off (the top of the test pattern is really scrunched down and the bottom is normal looking), and when I try to adjust that the screen goes blank and I can't get the screen to come back up.
I figured out the ion trap, it was just stuck in place because it hadn't been moved in years.

Another weird thing is that even adjusting the ion trap there's still a dark spot on the top of the screen when I adjust the linearity and height adjustments.

And yes I did have the correct connectors for this thing, the same connectors I used for my signal generator is the same connector that TV Analyst uses (BNC to alligator clip leads.)

I got the TV to give a proper raster but now I've hooked up the TV Analyst to the TV through the Video IF input and it showed the test pattern like it was supposed to but the linearity is way off (the top of the test pattern is really scrunched down and the bottom is normal looking), and when I try to adjust that the screen goes blank and I can't get the screen to come back up.
I figured out the ion trap, it was just stuck in place because it hadn't been moved in years.

Another weird thing is that even adjusting the ion trap there's still a dark spot on the top of the screen when I adjust the linearity and height adjustments.

And yes I did have the correct connectors for this thing, the same connectors I used for my signal generator is the same connector that TV Analyst uses (BNC to alligator clip leads.)

Good you got that working.

Now before you go crazy trying to set linearity on the Zenith... do you have a known good somewhat modern TV you can hook the B&K to, something to verify it didn't get it's own linearity messed up during shipment? It does have linearity adjustments very similar to a TV. And don't mess with them unless you have a TV that you know is very near perfect picture. You can even use the B&K Video out to go into composite video in on a newer TV. Here again it doesn't need to be perfect, you just need a reference so you know what it normally looks like. Everything is relative.

Good you got that working.

Now before you go crazy trying to set linearity on the Zenith... do you have a known good somewhat modern TV you can hook the B&K to, something to verify it didn't get it's own linearity messed up during shipment? It does have linearity adjustments very similar to a TV. And don't mess with them unless you have a TV that you know is very near perfect picture. You can even use the B&K Video out to go into composite video in on a newer TV. Here again it doesn't need to be perfect, you just need a reference so you know what it normally looks like. Everything is relative.

Yes I have several newer CRT Sets all of them are color sets, one is a Zenith 9" Color TV from 1986, and then I have a Monkey Wards 5" Color TV from 1982, and then I have a 13" Magnavox Color TV from 1991, and then I have my GTE/Sylvania 25" Color TV from 1974 and all 4 of those TVs have darn near perfect linearity.

OK. After you get that squared away it would be great if you could provide us a picture of what you're currently looking at on the Bugs CRT. BTW did you actually check to see what you replaced the 60uf cathode bypass cap with on the video out tube? When you moved the ion trap, were you able to make the picture brighter, or was it best were it was previously?

OK. After you get that squared away it would be great if you could provide us a picture of what you're currently looking at on the Bugs CRT. BTW did you actually check to see what you replaced the 60uf cathode bypass cap with on the video out tube? When you moved the ion trap, were you able to make the picture brighter, or was it best were it was previously?

When I moved the ion trap the screen would get brighter. The bypass cap for the 6CM7 tube was replaced with a 47 MFD cap with a 39 MFD cap in parallel to make 78 MFD, both caps are rated for over 100v.

The weird thing is that I actually had a really good picture on the TV going through the Tuner using my NES as a good stable video source and when I went to switch over to a converter box the picture went haywire and I wasn't able to get the tuner to lock in on the converter box signal, but yet it locked in rock solid with the NES.

What's up with that?

When I moved the ion trap the screen would get brighter. The bypass cap for the 6CM7 tube was replaced with a 47 MFD cap with a 39 MFD cap in parallel to make 78 MFD, both caps are rated for over 100v.

The weird thing is that I actually had a really good picture on the TV going through the Tuner using my NES as a good stable video source and when I went to switch over to a converter box the picture went haywire and I wasn't able to get the tuner to lock in on the converter box signal, but yet it locked in rock solid with the NES.

What's up with that?

78uf may possibility be too much. That tube needs to be biased "just right" in order to get vertical linearity in it's sweet spot, so that it interfaces well with the height and linearity controls. I have a 47uf in parallel with 22uf on mine which seems OK. Has something to do with were the tube amplifies relative to it's characteristics load line. :nerd:

Lot's of folks have reported very strange things a happening with converter box's. One thing we can be sure of , they were never designed for compatibility with older than dirt TV's. :D

78uf may possibility be too much. That tube needs to be biased "just right" in order to get vertical linearity in it's sweet spot, so that it interfaces well with the height and linearity controls. I have a 47uf in parallel with 22uf on mine which seems OK. Has something to do with were the tube amplifies relative to it's characteristics load line. :nerd:

Lot's of folks have reported very strange things a happening with converter box's. One thing we can be sure of , they were never designed for compatibility with older than dirt TV's. :D

Well lets see here, I did previously have a 59 uF capacitor (a 20 and a 39 uF capacitor in parallel with each other) in place of the 60 uF capacitor but then you had said that the capacitor needed to be 60 or more so then that's when I upped it to the 39 and the 47 uF caps.

Should I go back to the 59 uF cap?

I wonder if the converter box issue has something to do with how sensitive the tuner and IF is to switchmode power supply noise? Because I know the converter box works fine with my Meck TV strangly enough but then it might be because that TV isn't overly sensitive to outside RF interference such as that put out by SMPS.

Should I go back to the 59 uF cap?.

I honestly don't know for sure. I was just suggesting it on a hunch because I struggled to get the vert linearity straightened out on my own set. It's not a straight forward linear amplifier.


I wonder if the converter box issue has something to do with how sensitive the tuner and IF is to switchmode power supply noise? Because I know the converter box works fine with my Meck TV strangly enough but then it might be because that TV isn't overly sensitive to outside RF interference such as that put out by SMPS.

If your tuner is so sensitive it's possible your TV's AGC circuit isn't working correctly. You could try measuring the AGC DC control voltage at point D on the Sams schematic. It should be around positive 1.5v with no input signal, around -4.5v with a strong signal. As a reference I've measured mine using an older DVD/VHS player with an RF output. The key being you should see some kind of AGC voltage swing dependent on signal strength. If that's not happening you could try forcing point D negative by putting some negative DC voltage across that point and ground(positive goes to ground). Maybe a couple 1.5v batteries in series. Just remember that going more negative reduces the gain of the TV's front end. In the end you really shouldn't expect these old set's to operate reliably in a noisy RF environment, such as switch mode supplies in their near vicinity.

Here's what the TV looks like with my NES hooked up and running.

See picture below.

Here's what the TV looks like with my NES hooked up and running.

See picture below.

Excellent. Is that through the antenna input, and back to your 59uf cathode bypass?

Excellent. Is that through the antenna input, and back to your 59uf cathode bypass?

Yes to both. :thmbsp:

Yep the Bugeye is finally fixed for sure, and unfortunately the TV won't work with a converter box for sure, and it for sure has to do with the converter box's switchmode power supply because as soon as the converter box powers on you can hear and see the switchmode power supply oscillating through the TV's tuner.

I'll just have to use an RF Modulator to hook a VCR or DVD Player up to the TV and just use the TV to watch movies on.

It's possible if you feed the composite audio/video from the converter box to the VCR and let the VCR modulate it into RF that you'll be able to watch the converter box on the bugeye.

Yep the Bugeye is finally fixed for sure, and unfortunately the TV won't work with a converter box for sure, and it for sure has to do with the converter box's switchmode power supply because as soon as the converter box powers on you can hear and see the switchmode power supply oscillating through the TV's tuner.

I'll just have to use an RF Modulator to hook a VCR or DVD Player up to the TV and just use the TV to watch movies on.

What brand and model is the offending converter? Is the power supply internal or a wall wart?

What brand and model is the offending converter? Is the power supply internal or a wall wart?

I have 2 converter boxes, and both of them do the same thing, one of them is a "Zenith" model DTT901 and the other one is a "Magnavox" model TB110MW9 and both of them have a built in power supply (no wallwart.)

Although now I'm beginning to suspect something else. By any chance is the frequency at which channel 3 and 4 are running at on the NES RF modulator at a different frequency than the channel 3 and 4 on the RF modulator on the converter boxes?

I'm asking because I even tried a radio shack RF Modulator (of the variety that has RCA and S-Video inputs on the back so that you can make a TV without A/V inputs have A/V inputs) and not even the Radio Shack RF Modulator would work with this TV.

Any ideas? :scratch2:

You should be able to set the RF output of the converter box to ch 3 or 4. Can you test that by plugging into one of your newer TV's?

You should be able to set the RF output of the converter box to ch 3 or 4. Can you test that by plugging into one of your newer TV's?

They are both set to channel 3 as far as I know. The reason I asked about the frequencies of channel 3 and 4 on my NES vs my converter boxes is because I know that in Japan even though they used NTSC just like we did, their channel frequencies were slightly different than ours were especially on the lower VHF channels like 2-6, the reason I know about this is because I saw the video Shango did on a late 1960s Hitachi Console TV that was originally meant for the Japanese market and when he worked on it he had to use different channel settings to get stuff to come in correctly on it.

They are both set to channel 3 as far as I know. The reason I asked about the frequencies of channel 3 and 4 on my NES vs my converter boxes is because I know that in Japan even though they used NTSC just like we did, their channel frequencies were slightly different than ours were especially on the lower VHF channels like 2-6, the reason I know about this is because I saw the video Shango did on a late 1960s Hitachi Console TV that was originally meant for the Japanese market and when he worked on it he had to use different channel settings to get stuff to come in correctly on it.

But as far as we know both of those boxes were made for the US market? Right now as I'm typing I'm watching my Bugeye through that same Magnavox converter with the RF output set to ch 4. The only issue I have is these Zeniths buzz with text on the picture, which seems pretty common.

Are you aware of the fine tuning control on the back side of the tuner, and also there's a local oscillator adjustment for each channel that's accessible though the little round hole in the upper back side of the tuner?
If you don't have channel 3 or 4 precisely tuned you could potentially pick up all sorts of noise.

But as far as we know both of those boxes were made for the US market? Right now as I'm typing I'm watching my Bugeye through that same Magnavox converter with the RF output set to ch 4. The only issue I have is these Zeniths buzz with text on the picture, which seems pretty common.

Are you aware of the fine tuning control on the back side of the tuner, and also there's a local oscillator adjustment for each channel that's accessible though the little round hole in the upper back side of the tuner?
If you don't have channel 3 or 4 precisely tuned you could potentially pick up all sorts of noise.

Ok, well I wasn't aware of those extra adjustments as my Sam's folder didn't mention those settings (at least not that I was aware of.) Also when I hooked up my NES to the TV which was set to channel 3 the only setting on the tuner that the NES came in at half way decently was when the tuner was set with channel 3 at the 6 o'clock position (3 is facing up) and nowhere else (so my TV has channel 3 at the 6 o'clock position and not at the 12 o'clock position like yours is).

But as far as we know both of those boxes were made for the US market? Right now as I'm typing I'm watching my Bugeye through that same Magnavox converter with the RF output set to ch 4. The only issue I have is these Zeniths buzz with text on the picture, which seems pretty common.

Are you aware of the fine tuning control on the back side of the tuner, and also there's a local oscillator adjustment for each channel that's accessible though the little round hole in the upper back side of the tuner?
If you don't have channel 3 or 4 precisely tuned you could potentially pick up all sorts of noise.
I was trying to find a picture of the VHF tuner.
I remember my Zenith set had a tuner that was unusual in a Zenith.
Maybe, just trying another 5U8 would help.

Now that you mention it my chassis is a 16Z21 which has the alternate VHF tuner shown in Sams page 12, so what I told you about the fine tuning and osc adjustments may not apply to yours. Otherwise schematicly our two chassis are identical as far as I can tell. This tuner almost looks like a standard coil unit with interchangeable channel modules.

https://live.staticflickr.com/6553/51806802711_37d5849aaa_c.jpg

https://live.staticflickr.com/65535/51807161359_b6e0c07e21_c.jpg

OK I'm very sorry for the mix up, but the Sams for your TV doesn't even show my tuner on page 12. I have 2 Sams folders and the Riders all sprawled out for these TV's and it's all gotten just a little disorganized. :D But I did just look at the Sams for your set and it appears you have a circle of holes in the front side of your tuner that should be your local oscillator adjustments. But I'm going to go study that some more right now. :)

Does this page 7 match your Sams? Clearly shows the front local oscillator adjustments along with the channel number designations. I would think as long as you've already twerkulated your IF slugs there would be very little harm in trying to fine tune the oscillator adj. associated with either channel 3 or 4. This drawing also explains why your channel positions don't match mine. :yes:

https://live.staticflickr.com/65535/51807586540_ff252c2ebc_o.jpg

The NES, DTV boxes and TV are all US market. The Japanese marker version of the NES (called the Famicom) looks wildly different from the US market version to the point that side by side you wouldn't think in your wildest dreams that they were the same device. Japan also uses an incompatible DTV standard so a Japanese DTV converter wouldn't reciever anything in the USA.

Also Japanese low band VHF channels are off a country mile from US channels. The North American VHF band goes CH2-6(54-88MHz), 88-108MHz FM radio, some public service 2-way stuff, CH7-13(174-216MHz).
The Japanese VHF band went FM radio 76-90MHz (IIRC), CH1-3(90-108MHz), other things, CH4-12 (170-222MHz)...So the lowest frequency overlap would be US ch7 which mostly overlaps Japanese cut and a bit of the top of CH4.

Having seen Japanese VCRs (and owning a recently imported used Japanese domestic market ED-BETAMAX) I can tell you that most Japanese market VCRs and games use Japanese CH1 or 2...Which are both squarely in the US FM band....US CH6 fine tuning MIGHT be able to get japanese CH1 in some cases.

OK I'm very sorry for the mix up, but the Sams for your TV doesn't even show my tuner on page 12. I have 2 Sams folders and the Riders all sprawled out for these TV's and it's all gotten just a little disorganized. :D But I did just look at the Sams for your set and it appears you have a circle of holes in the front side of your tuner that should be your local oscillator adjustments. But I'm going to go study that some more right now. :)

My TV is the one covered in Sam's 333-17.

Yes the tuner on my TV has 13 adjustment screws arranged in a circle in front of the tuner that are marked 2-13.

I was thinking I might just see if I can hook the 1076 up to the tuner on my TV via the VHF antenna terminals on the back and then tune in each respective channel on the 1076 and check the tuner adjustments.

I'm just curious but when got this TV and first started working on it the 5BK7 RF tube in the VHF tuner was subbed out years ago apparently with a 4BQ7 tube, and I'm just wondering but could it be possible that someone had to tweak the tuner adjustments when they installed the 4BQ7 tube into the tuner in place of the original 5BK7 tube to get the tuner to function properly with that tube?

Now that you mention it my chassis is a 16Z21 which has the alternate VHF tuner shown in Sams page 12, so what I told you about the fine tuning and osc adjustments may not apply to yours. Otherwise schematicly our two chassis are identical as far as I can tell. This tuner almost looks like a standard coil unit with interchangeable channel modules.

https://live.staticflickr.com/6553/51806802711_37d5849aaa_c.jpg

https://live.staticflickr.com/65535/51807161359_b6e0c07e21_c.jpg

Yeah that's definitely a way different tuner than I have in mine, I think yours is a bit earlier than mine as yours appears to be a VHF Only model and mine is the VHF/UHF model.

Yeah that's definitely a way different tuner than I have in mine, I think yours is a bit earlier than mine as yours appears to be a VHF Only model and mine is the VHF/UHF model.

A little update, I hooked up the 1076 to the antenna terminals on the TV and sure enough you were right the first time, Channel 3 pointing up to the 12:00 position was indeed the correct position because as soon as I tuned the tuner to that position the 1076 came in loud and clear, it was just a matter of me having the tuner in the wrong position the whole time. :scratch2:

A little update, I hooked up the 1076 to the antenna terminals on the TV and sure enough you were right the first time, Channel 3 pointing up to the 12:00 position was indeed the correct position because as soon as I tuned the tuner to that position the 1076 came in loud and clear, it was just a matter of me having the tuner in the wrong position the whole time. :scratch2:

Very interesting. While the 1076 is a great trouble shooting tool, don't go so far as to assume it's an ideal frequency standard. But once you've established what's what, you can fine tune any channels local oscillator to whatever signal source you're wanting to watch. Essentially you're shifting the tuners's mixer IF output to accommodate whatever state of alignment your IF is at. The local oscillator can tune over a broader range, while the IF is optimized for a relatively narrow response.

A little update, I hooked up the 1076 to the antenna terminals on the TV and sure enough you were right the first time, Channel 3 pointing up to the 12:00 position was indeed the correct position because as soon as I tuned the tuner to that position the 1076 came in loud and clear, it was just a matter of me having the tuner in the wrong position the whole time. :scratch2:

With ch 3 at the 6:00 position, I suspect that ch 9 was at the 12:00 position, so the tv was actually tuned to ch 9. Ch 9 (186-192 mHz) falls in the range of the third harmonic of ch 3 (60-66 mHz), so is likely that the NES has a much stronger third harmonic output than your other devices, (poorer quality modulater). :thumbsdn:

jr

With ch 3 at the 6:00 position, I suspect that ch 9 was at the 12:00 position, so the tv was actually tuned to ch 9. Ch 9 (186-192 mHz) falls in the range of the third harmonic of ch 3 (60-66 mHz), so is likely that the NES has a much stronger third harmonic output than your other devices, (poorer quality modulater). :thumbsdn:

jr

OK, so that exlains why I was able to get the NES to come in so well at the wrong channel (CH. 9 rather than CH. 3.)

It looks like what I need to do is set my converter box and RF Modulator to channel 3 hook them up to the TV antenna input and then fiddle with the local oscillator adjustments for channel 3 until it shows a proper image on the screen and then adjust the fine tuning knob (UHF Tuner Knob) and go from there.

I think other than the channel selector confusion I think we can call the Bugeye TV as good as fixed! :thmbsp:

Now onto trying to figure out the Big Zenith! :yes::D

A little Update: I hooked my B & K 1076 up to the IF Input on the 23" Zenith and I was able to get a weak intermittent IF Signal on the TV and so I twerkulated the IF tubes in their sockets just to see if maybe there was a loose or intermittent connection in the tube sockets and sure enough I wiggled the 6EJ7 3rd IF tube and the IF signal would go in and out intermittently and so I removed the tube (it was the original Zenith badged Telefunken tube) and so I replaced it with a NOS GE 6EJ7 tube and sure enough the IF circuitry woke right up and was producing a nearly perfect picture (except for a little weird issue at the top of the screen, which is I think a vertical issue, but maybe you guys can tell what it is when you look at the pictue I took of the screen on the TV.)

This TV has a really nice bright raster yet which tells me that for sure this was definitely a low hours TV (possibly just used as furniture, or only used on special occasions.)

one thing can't figure out is that the backlight circuitry on this TV for the tuner is kind of intermittent for some reason.

When you first turn on the TV the tuner backlight is dead (isn't glowing) and then after the TV warms up a bit then the backlight comes on and when you "scan" through the channels the pilot light for the UHF tuner won't come on right away when you hit the "UHF" position, I have to smack the side of the TV a little bit and then it comes on.

Any ideas as to what's going on here?

See picture below for a view of what the screen currently looks like on the 23" Zenith.

P.S. I never touched the IF cans in this TV, the picture that this TV is producing right now (as seen in the picture below) is how the IF cans were set when I got the TV.

Primarily a vertical linearity issue. Could be linearity and/or height control or a cap. I don't have any service info so I'm not of much help.

If your tuner has this switch on the back, it's purpose is to switch on the UHF B+ and dial light. The 3 back connections are for the lights. The left terminal is the common one, usually has a brown wire connected to it, and the VHF light connects to the right terminal, UHF light connects to the middle terminal. On channels 2-13 the two outside terminals have continuity, when the UHF position is selected, the right terminal disconnects from the left and the center terminal is now connected to the left one. Your switch needs cleaning. It can be opened up and fixed, just be careful parts don't spring out!

I wouldn't open the switch up. Just give it a shot of Deoxit or similar. Then let it work a few cycles.

Primarily a vertical linearity issue. Could be linearity and/or height control or a cap. I don't have any service info so I'm not of much help.

well that's what I was thinking as well, and I was trying to adjust the height adjustment (called Vertical Size on this TV) but that control is inset within the Peak Picture control and I can't seem to adjust it because none of my screwdrivers I have are long enough to go inside that Peak Picture contol knob to adjust the Vertical Size Adjustment. :thumbsdn: :sigh:

I wouldn't open the switch up. Just give it a shot of Deoxit or similar. Then let it work a few cycles.

I'll give it a shot. :thmbsp:

I'm just curious, but can missing centering rings cause the issues my TV is having with the weird linearity issues?

Hi Vortalexfan.in the past,if I needed a long skinny adjustment slot screwdriver,I would take a piece of coathanger and hammer one end flat.then take a file and clean up the end.then bend a 90 deg at the other end for a handle..has worked well for me. RonL

I actually did end up finding a screwdriver that worked.

OK, so I had a really weird issue just come up on my 23" Zenith TV, C61 which is apparently a bypass cap of some sort for the Horizontal Output Tube just went up in flames literally, which I was able to extinguish the flame by blowing it out like a candle (it was burning like a candle would.)

any ideas as to what would cause that to happen?

Do you think that this issue might have something to do with the weird linearity issues that I was having?

I posted a screenshot of the schematic showing the part of the circuit where the strange failure took place.

Looks like the cap just randomly decided to short. No doubt the resistor supplying B+ cooked also.

Looks like the cap just randomly decided to short. No doubt the resistor supplying B+ cooked also.

OK, well it was a modern replacement cap (the yellow film variety) and it was one i had salvaged out of a radio I had recapped a couple of years ago that I ended up having to scrap out because I wasn't able find some parts to fix the rest of the radio.

That B+ Supply Resistor was an 8.2kOhm 3W resistor so not a very common value...:scratch2:

OK so here's a picture of the burned up capacitor, has anyone seen a capacitor fail like this before, especially one that's only a couple years old?

OK so here's a picture of the burned up capacitor, has anyone seen a capacitor fail like this before, especially one that's only a couple years old?

You probably ruined it when you salvaged it...the plastic sides and dielectric/foil roll melt easily. If you accidentally touched your iron to the side of the cap and melted it a bit you could have shorted together the 2 capacitor metalized plastic plates, or damaged the dielectric enough to make failure easier.

I've ruined a few yellow caps with my iron myself....I don't like that they can melt easily so I only use them if I'm restuff paper caps or dealing with a situation where I need extra long leads and I don't want to Western Union splice longer leads on.

Also, that thing is always being hammered by high freq AC by the horz circuits,I always go for something at least 100v higher than the original rating.

Also, that thing is always being hammered by high freq AC by the horz circuits,I always go for something at least 100v higher than the original rating.

The original cap was a .047 uF 200V and the replacement I installed was a .047 uF 630V capacitor...:scratch2:

You probably ruined it when you salvaged it...the plastic sides and dielectric/foil roll melt easily. If you accidentally touched your iron to the side of the cap and melted it a bit you could have shorted together the 2 capacitor metalized plastic plates, or damaged the dielectric enough to make failure easier.

I've ruined a few yellow caps with my iron myself....I don't like that they can melt easily so I only use them if I'm restuff paper caps or dealing with a situation where I need extra long leads and I don't want to Western Union splice longer leads on.

Well I had replaced the burned up one with another one and for some reason the picture tube is glowing a purplish color inside the neck near the socket, and I'm not getting any picture on the screen.

Well I had replaced the burned up one with another one and for some reason the picture tube is glowing a purplish color inside the neck near the socket, and I'm not getting any picture on the screen.

NOT GOOD

that means the CRT is gassy. like seen here
https://www.flickr.com/photos/70039806@N00/5379156237/

Running it with a bad tube like that can cause all sorts of nasty feedback problems.

NOT GOOD

that means the CRT is gassy. like seen here
https://www.flickr.com/photos/70039806@N00/5379156237/

Running it with a bad tube like that can cause all sorts of nasty feedback problems.

What would of caused it to do that? Because it wasn't doing that before, the picture tube was running normally (no purplish glow) up until that capacitor failed.

What would of caused it to do that? Because it wasn't doing that before, the picture tube was running normally (no purplish glow) up until that capacitor failed.

you need re-check all voltages on the CRT, who knows what that did when the cap let go.

stick it on a CRT tester and see if it still has emissions.

is the HV still good, and not AC somehow.

for you to be seeing purple in the CRT elements, something is VERY wrong, and usually that is a tip off of air have gotten in there somehow.

you need re-check all voltages on the CRT, who knows what that did when the cap let go.

stick it on a CRT tester and see if it still has emissions.

is the HV still good, and not AC somehow.

for you to be seeing purple in the CRT elements, something is VERY wrong, and usually that is a tip off of air have gotten in there somehow.

I don't have a CRT tester, I do have a Knight tube tester that can be used to test CRTs but I don't have the special adaptors to convert the Knight tube tester into a CRT checker.

Sometimes the glass spontaneously cracks from manufacturing defects or improper care/handling.

Case in point back in October I found a CTC16 with a ruined flyback, and an OK 21FBP22. I installed that 21FBP22 in my Zenith Franken Chancellor and it worked fine for an hour (2 half hour runs) then the glass spontaneously cracked at one of the base leads and it took in air and failed gassy.
Once a CRT gets gassy enough that it stops displaying an image, lugs down the HV, and starts glowing purple in the neck that tube is usually FUBAR.
I had to source another tube after mine cracked.

I just thank my lucky stars I'm not miniman82....He had a basically priceless metal cone prototype of the 15GP22 spontaneously crack and fail on him... Loosing a tube that irreplaceable has to royally suck!

and having a gassy CRT can cause all sorts of weird feedback issues, that COULD be what toasted the cap.

Sometimes the glass spontaneously cracks from manufacturing defects or improper care/handling.

Case in point back in October I found a CTC16 with a ruined flyback, and an OK 21FBP22. I installed that 21FBP22 in my Zenith Franken Chancellor and it worked fine for an hour (2 half hour runs) then the glass spontaneously cracked at one of the base leads and it took in air and failed gassy.
Once a CRT gets gassy enough that it stops displaying an image, lugs down the HV, and starts glowing purple in the neck that tube is usually FUBAR.
I had to source another tube after mine cracked.

I just thank my lucky stars I'm not miniman82....He had a basically priceless metal cone prototype of the 15GP22 spontaneously crack and fail on him... Loosing a tube that irreplaceable has to royally suck!

Well how hard would a 23EDP4 picture tube be to locate?

and having a gassy CRT can cause all sorts of weird feedback issues, that COULD be what toasted the cap.

Including maybe linearity issues? I'm asking because this TV had some weird linearity issues on the top of the screen when I got it going. See my picture several posts back to see a picture of the linearity issues I was talking about.

Well how hard would a 23EDP4 picture tube be to locate?

ETF has 2

https://docs.google.com/spreadsheets/d/e/2PACX-1vSz0V8WEE-neLfF0RzkPKv8QOJlyb_VbvIZ8c4XvN0w-4ZDIdpSEPvGHPiq2W9E2k32Qs8VkpuEQkkm/pubhtml?gid=832382218&single=true

ETF has 2

https://docs.google.com/spreadsheets/d/e/2PACX-1vSz0V8WEE-neLfF0RzkPKv8QOJlyb_VbvIZ8c4XvN0w-4ZDIdpSEPvGHPiq2W9E2k32Qs8VkpuEQkkm/pubhtml?gid=832382218&single=true

Ok, how do I get one from them?

Ok, how do I get one from them?

their email is [email protected]

you can contact them with your request , that is the best way,

Steve McVoy should get back to you sooner or later! :)

their email is [email protected]

you can contact them with your request , that is the best way,

Steve McVoy should get back to you sooner or later! :)

Ok, thanks! :^) Sorry for all the questions, I've never gotten a picture tube before from them, which is why I asked.

How it normally works is, Steve will give a ballpark cost for the tube ( item + shipping & packing ), while the check inventory, this can sometimes take a while as they are only at the location on the weekend.

In the meantime, you can use this time to go over your set with a fine tooth comb, looking for any damage, be it a direct cause of, or a secondary symptom of this CRT failure.

This can include CRT socket & wiring and related circuits.
Flyback transformer & HV elated circuits including boost and focus.
Deflection yoke and related circuits, while paying close attention to the horizontal windings, there is a great deal of voltage potential on these windings, and if anything went wrong here, ( shorted turn, or short to dag etc ) , it has a chance of creating a hotspot, and could crack the neck.

Not saying that this is what happened to you but, you wanna be SURE that it did not! :)

How it normally works is, Steve will give a ballpark cost for the tube ( item + shipping & packing ), while the check inventory, this can sometimes take a while as they are only at the location on the weekend.

In the meantime, you can use this time to go over your set with a fine tooth comb, looking for any damage, be it a direct cause of, or a secondary symptom of this CRT failure.

This can include CRT socket & wiring and related circuits.
Flyback transformer & HV elated circuits including boost and focus.
Deflection yoke and related circuits, while paying close attention to the horizontal windings, there is a great deal of voltage potential on these windings, and if anything went wrong here, ( shorted turn, or short to dag etc ) , it has a chance of creating a hotspot, and could crack the neck.

Not saying that this is what happened to you but, you wanna be SURE that it did not! :)

I think that's what I'm going to do, and also finish the final touches on the Bugeye TV.

Thanks for the heads up, as like I said this is the first time I've ever gotten this heavily involved in repairing TVs, in the past I've only ever done minor repairs like vertical and horizontal hold adjustments on 1980s TVs and or replacing blown fuses in TVs that were inadvertently shorted by the power cord being partially unplugged from the wall and a metal legged chair shorting up against the plug, or adjusting picture and color adjustments on TVs.

Besides my Meck and my RCA and now these Zeniths I'm relatively new to repairing tube powered TVs (I've only ever repaired Solid State TVs up to that point.)

It appears your yellow screen grid bypass cap was jammed right up tight against the Horizontal Output plate lead soldered to pin 7. That's the Do Not Measure point on your Sams schematic. Speculating but it's possible high voltage burned through the outer plastic film trying to get to the ground layer. Or the socket terminal could have knifed through the insulation. It also looks charred down inside the center of the socket base. The 8.2k doesn't show any sign of heat, so it likely was not part of the short.

https://live.staticflickr.com/65535/51815482854_693e59fb33_c.jpg[/url][url=https://flic.kr/p/2mWKTQ3][/img]

It appears your yellow screen grid bypass cap was jammed right up tight against the Horizontal Output plate lead soldered to pin 7. That's the Do Not Measure point on your Sams schematic. Speculating but it's possible high voltage burned through the outer plastic film trying to get to the ground layer. Or the socket terminal could have knifed through the insulation. It also looks charred down inside the center of the socket base. The 8.2k doesn't show any sign of heat, so it likely was not part of the short.

https://live.staticflickr.com/65535/51815482854_693e59fb33_c.jpg[/url][url=https://flic.kr/p/2mWKTQ3][/img]

Well that's actually right near where the original cap ran, the only difference was that the original cap was a bumblebee cap that had a non-conductive plastic cover over the paper and foil electrolyte roll.

But I do see what KK was getting at, that cap should have been as far away as possible from that joint, where as the cap is like rated 630v, or what ever, the voltage at that point is MUCH higher, and could very easily find a way to burn into the outer layer of the newer cap, where it did not of the older style one.

There is also a chance the wire to pin 7 is damaged ( carbonized) needs to be looked at closely.
Not only could this high voltage found a path to ground, but it may also have gone the other way to the bias on the other side of the 5w resistor, and hit your CRT, (not sure of how your set is wired), but via focus or the brightness or video output.
Thus I mentioned having to check stuff.

Ok so I finally got the Bugeye TV going the rest of the way. 👍😁
See picture below for the screenshot I took.