Yes, it's just a 12AU7. I foolishly bought the gold plated version of the ECC-82 from AES thinking that it would be more reliable and have better controlled characteristics if I had to replace it in the future.

JJ doesn't list this version on their web site anymore, which is interesting. AES still carries it.

I'm pretty sure the light bulb effect was because of a heater-cathode short. I looked at the schematic of the Precision 10-12 and when you set it up for a particular tube the first state that it will be in is with the filament return selected and all other pins connected to filament supply. With a cathode-heater short, say in the middle of the filament, then it's like applying 6.3VAC to a 3VAC filament. The cathode that is connected to pin 3 is shorted to the heater, but there's no way I could prove that it didn't happen after the burn-out.

I'm going to check the ECC-82 that I have in the vertical section with a leakage checker first.

Thanks for the offer of the 12AU7s. I just bought four "Baldwin Sylvania" 12AU7s on ebay for less than I paid for a gold ECC-82.

John

The ECC-82 was working even with the shorted heater/cathode because the cathode of that section is at DC ground anyhow. *I meant to also say that the filament supply is isolated.* It just injected some hum, which I had noticed. There had been a very small slow weave of the dot pattern. It would reduce the feedback in the horizontal oscillator a little bit.

I put in a 12AU7 that I had taken out of the set. It's at the low end of the good scale, nearly in the weak when I test it. Using it I get insufficient horizontal width and fold-over on the right. I hope the ones I ordered are strong.

I was surprised that it performed so poorly with this tube so I did some more checking. I found one resistor out of tolerance by 20%. It's a 10% resistor. Probably shouldn't matter too much but I'll replace it. Another one is off by 20% and one is just the wrong value. It looks like someone replaced it using the schematic from the previous production change and not the current one for this chassis. This ends up shifting the grid bias on the Horizontal Discharge half of the 12AU7.

The 6BD5 horizontal output tube seems strong and I didn't find anything wrong in that section.

John

One step forward
 

I decided that R151, 470K being high by 20% shouldn't be problem since they used a 2.2meg in the previous version. I was wrong about R152 being the wrong value installed, I misread the bridge number in the schematic. R155 is a bit high, but again shouldn't cause a major problem. I tried various 12AU7's and still had the folding on the right. I decided to take the JJ ECC-82 from the vertical section and try it expecting to have the horizontal back the way it was. No, changer other than improved width.

I then did the horizontal alignment. This was much easier than the first time since there was much less interaction between the adjustments. Everything behaved as it should. I ended up with a nice horizontal alignment. This makes me believe even more that the brand new ECC-82 that I had used originally, had a heater/cathode short to begin with.

If you want to read about how the alignment is done you can find it at:
Service Manual

It uses the following supplements:

Supplement-1

Supplement-2

I have chassis C15 and bridge B17.

While the effects are obvious, I don't understand why the charge peaking resistor R211 needs to be shorted in the first part of the adjustment, or what the ringing coil L60 does.

An oddity is the 20MFD electrolytic paralleling a fuse. It's C219 around F1. Any ideas on that would be appreciated.

John

Two steps back...
 

I was still having a problem with focus on the right hand side of the raster. Jr_tech's suggestion made the most sense so even though I didn't see a ripple in the screen bias I added, I decided to check it again.

I foolishly decided to try a different 6BD5GT HOT at the same time. I didn't get a raster and no HV. I checked the fuses and F3 was blown so no -125V.

I checked the 6BD5 I put in and it was at 100% where a NOS tube should be 70%. I probably should have reduced the horizontal width before turning it on. F3 used to be 1/4amp but they upped it to 0.3amps. Probably still marginal. Replacing it and going back to the first 6BD5 didn't bring back the HV though. I did all the tests I can without removing the HV assembly from the bridge and everything looks o.k. Fortunately the HV RF transformer seems good. That would really be unobtainium.

Maybe the 6Y6 went bad just by coincidence. Except for taking out the fuse, I don't see why the 6BD5 would make the HV go away. The heater of the 6W4 is isolated so a short there shouldn't matter either.

The radio works so the +170 and +180 must be o.k. I'll have to swap the 6Y6 and if that doesn't work, then start troubleshooting.

John

** I forgot, there was something else I did differently too. I had left the TV in the radio position when I shut the AC off. It was still in this position when I turned the AC back on. The HV section still has +170 and -125 supplied to it when the radio is on, but the filament of the 6Y6 is off. Maybe the 6Y6 didn't like waking up this way. Guess I'll find out when I sub it. **

My dad had cut 1/4" off the bottom of the molding in front of the TV section to make room for the cedar boards to fit. You can see the cut in the first photo.

I carefully measured the radius of the bead and bought a beading bit for my router. Although it's obvious in the second photo, I didn't notice that the step isn't perpendicular to a tangent of the arc. I could still use the router bit to make a replacement molding, but I'd have to do it in two steps. First make the bead at the appropriate angle, then go back and make another cut to square up the step. The second cut would have to be precise.

It turns out that the molding goes up 1/2" under the top front trim so all I really have to do is remove the molding and slide it down to the bottom. The top will still be hidden by the trim.

Well, if I break the second molding removing it I at least have a cutter to try to make a replacement.

John

Well, the lack of HV turned out to be the 6Y6. I put in a new one and I got a solid 11KV. Maybe there's something to this cathode stripping theory after all. I hope not, I like to listen to the radio on this set and that biases the 6Y6 with the heater off.

With the higher HV the horizontal width is marginal. I have to turn the width control to the end. I tried the NOS 6BD5 that I thought killed the B- supply. I turned the width to minimum first. It gave me a raster, then as I turned the width up it would soon start to collapse. Eventually, even at a reduced width bad things started to happen. I wasn't sure if it was Barkhausen or breakdown. It caused static in the audio and looked scary enough that I immediately shut it off. The tube tests at 100% when it should test 70% if new.

I can improve the width by going to a 6BQ6. It's an easy change, but it would make it a bridge code B18 instead of B17. I'm not sure if I want the bridge to be different than the version stamped on it.

This and the 12AU7 are two bad tubes in one lot from AES. I can't blame them, but the next time I order any tubes I'll test them in circuit immediately upon receipt. I have a small stock of bottle shaped 6Y6's. I have two really good ones from eBay. Looks like I'll need to obtain a few more.

The focus is better, but when using a dot pattern it's clear that it's an astigmatism. I can correct it with a weak external magnet. The next time I have the CRT out I'll try degaussing the yoke support and play around more with the location of the focus magnet. If that doesn't work I guess I'll resort to mounting a weak magnet.

The photo is the plate of the horizontal discharge 12AU7 tube. The service manual shows a rounded sawtooth and it doesn't have the dip between the teeth that mine shows. Is this a problem?

John

In regards to the scope trace of the horizontal discharge tube plate, it looks like the trace I show is correct and the service manual is wrong. Later sets using the same exact circuit show traces like the one that I photographed.

Also, C219 that is shown paralleling fuse F1 is partially explained by Wallace's Telaides. It seems to help the fuse respond only to the average DC current and not the large peaks from the horizontal sweep. Also, they moved one end from the +180 to the +170 to help the horizontal oscillator start more reliably. I didn't think a fuse had a significant impedance, but it must if this helps.:dunno:

John

John,

That Sylvania of yours is a very curious beast. Sylvania definitely did their own thing, design-wise. I have several 10" and larger sets that use RF high voltage power supplies, and have always enjoyed them. I have never seen any other 40s vintage TV with a large capacitor across a fuse. Seems curious, probably not the best design. But a really interesting set from a technical point of view. Thanks for posting the service data.

Thanks John. To me the design seems straightforward because it's the first TV I was exposed to as a kid. I participated when my Dad did repairs, or when Gus Wall, our TV repair guy would make a home visit. And I actually enjoyed the smell of selenium rectifiers. Well, I admit the large cap across a fuse is strange..

From looking at old texts, data-sheets that I looked at nearly 50 years ago, and old magazines, I think Colonial Radio cut and pasted patented circuits and did some of their own weird stuff like the paralleled 5U4 and 7X6. The horizontal circuit seems to be from RCA. The RF HV, I'm pretty sure, is from Spellman who manufactured HV supplies for TV's. I think that's where they got their start.

6BD5 followup
 

I decided to try to understand why a 6BD5 that tested so good, performed so poorly. I guess if something seems to good to be true, it is.

The tube is definately NOS. The getter looks good at first glance, nice and shiny, but looks horrible when you shine light through it. I also noticed a slight haze on the envelope around the plate area.

So, I put it back on the tube tester and turned out the lights. When I did the dynamic test there was a blue glowing haze between the plate and cathode. The tube is gassy. It acts like it has higher emission, but is really gassy.

The supplier only gives a 10 day warranty period and I tend to be too trusting. I'm dissappointed that I had two bad tubes in one order. I've had better luck with eBay. I'll still use them but I'll test as soon as I receive any tubes and I have a better idea of what to look for now. Hopefully I won't fool myself like I did with the gassy tube.

I have a Senecore LC3 leakage tester which works great for the tubes it handles, but it doesn't do the 6BD5 or 6Y6. The Precision 10-12 will find shorts, but doesn't do a sensitive leak test. But I have seen 1B3's glow blue from gas with it and now the 6BD5.

I'm tempted to try a 6AU6, would that make a good substitute for a 6BD5?

John

"I'm tempted to try a 6AU6, would that make a good substitute for a 6BD5?"

huh?:saywhat:

jr

Oh, I get it... My substitution book sez 6AU5 6AV5 6FW5 if not series filament circuit.:yes:

Oops! Typo. The filaments are all parallel so there's no problem there.

Actually I wasn't wearing my glasses and a 5 looks alot like a 6 when it's smeared out... Thanks for pointing that out.

John

The 12LP4 that Scotty has rebuilt with a rebuilt gun came today. I installed it and it works great! I still have to figure out the focus issue though.

I might have to go back to the 10MP4 just to make sure that something else didn't change or fail coincidentally.

John

Awesome - I'm glad someone is still rebuilding CRTs!

Still trying to figure out the focus issue on the right side. I tried rotating the focalizer 180 degs but that had no effect. I thought that if it was at fault that the problem would switch to the left side.

I scoped all the voltages including the HV. They're stable. Only the HV shows any structure and I don't believe it's enough to cause the problem.

All the photos have a vertical scale sensitivity of about 60V/div. It was AC coupled using a 20KVDC, max pulse 40KV scope probe.

In the first photo you see the pips correspond to the horizontal retrace. The rest of the variation is due to the video signal. The second photo has the time base set to view the vertical sweep period and the fuzz is the horizontal retrace pips. In the last photo I turned the brightness down and all you see are the horizontal pips.

I think the horizontal pips are capacitively coupled from the windings on the yoke to the aquadaq, which is capacitively coupled to the dag on the inside connected to the HV. The horizontal windings are closest to the neck of the CRT.

The HV was about 11KV during this test. The variation appears to be about 50 volts PP. I doubt that 50 volts would affect the focus much.

The resistor in series with the HV supply is about 470K. So, 50 volts means about 100 micro-amps, which is probably reasonable with the brightness set high.

I looked at the old test pattern photos I took with the 10MP4 and I see that it has the same problem, just to a lesser degree. I'm starting to think that the problem is with the yoke.

I'm going to ring test the yoke and perhaps swap the horizontal leads to see if the focus issue moves to the other side of the screen or stays put.

John

"I'm going to ring test the yoke and perhaps swap the horizontal leads to see if the focus issue moves to the other side of the screen or stays put."

That experiment should be interesting!

"20KVDC, max pulse 40KV scope probe"

6015A?

jr

Yes, but not mine. I borrowed it.

John

I ring tested the yoke with a Sencore LC101. If the yoke is good it's supposed to give 10 rings or more. I got 9 max. Not definitive.

The DC resistance is supposed to be 36 ohms. I measured 47 ohms. The yoke is a bit different in that the horizontal windings are in parallel. This would mean that each coil should be 72 ohms. If I assume the difference is due to one coil, then it would have a resistance of about 135 ohms. Quite a bit different.

I swapped the horizontal leads and while the raster reversed, the focus problem remained on the same side. This, along with trying to rotate the focus magnet and moving to different positions has no effect on the problem leads me to believe that the yoke has a problem.

Another clue is that it appears that someone replaced on of the horizontal leads with HV wire. It has a polyethylene core and a plastic jacket. All the other leads are fabric coated.

https://www.msu.edu/~yurkon/Photos/young_einstein.jpg
Normal

https://www.msu.edu/~yurkon/Photos/Hleadsswapped.jpg
Reversed

The ringing is probably due to the long jumpers I used to connect the yoke.

Notice that the keystoning is the same for both. If it was a supply issue it should be reversed when I reversed the leads.

It looks like I need to search for a yoke.

I would need a Sylvania 100-0001 or a 100-0002 and a horizontal choke 241-0002. The second version has a center tapped yoke instead of parallel windings and thus needs a center-tapped choke. I'd call it a transformer, but they call it a choke.

The Merit numbers would be MD-13 for the yoke and C-2980 for the choke.

If anyone can provide Thordarson or other cross reference numbers that would be great. The actual parts would be even better! ;)

John

If you rotate the yoke 90 or 180 degrees does the area of poor focus follow the mechanical rotation of the yoke? If it still stays on the right hand side of the tube, perhaps some steel part near the neck of the CRT is magnetized ?

jr

I can probably only rotate the yoke over a +/-15degree angle. But that's probably enough to do the test you suggest.

I don't think it's a magnetized part of the chassis. The point at which the focus gets bad follows a vertical line. I wouldn't expect it to follow a straight line line if it's the chassis.

It's a good test though, if the bad focus rotates too, then it has to be the yoke.

John

I have a Sylvania yoke that is similar to the one in the set. I just did a ring test on it and got 25 rings. Quite a bit more than the one in the set.

Sencore says to make a shorted copper loop and place it around the yoke windings. If the number of rings doesn't change by a lot, then there is probably a shorted turn.

I'll have to try that along with rotating the yoke over its limits.

But, not tonight...

John

I finally scored a hit with Moyer's. They have a RAM yoke that will replace either the 100-0001 or 100-0002 Sylvania yoke. I don't think that there are many of these around so it won't hurt to have one on hand even if it turns out that the yoke is o.k.

John

Sorry I don't have time to read this lengthy (and great) thread, but that looks like an h-linearity problem to me. See how it's all stretched out on the right hand side in the second pic?

That's true, but is only due to the temporary connection by the use of jumper leads. It's not part of the focus problem that I'm concerned with.

John

I tried rotating the yoke over the limits of it's travel as suggested by jr_tech. I used a dot pattern to judge whether the focus problem followed the rotation or not. It follows the yoke.

I'm getting more and more convinced that the problem lies with the yoke. I should find out soon, when the RAM yoke arrives.

John

I received the RAM replacement yoke today. I tried ring testing the horizontal and saw 33 rings as opposed to the 9 rings I saw with the original yoke.

I don't think I'll get a chance to install it this weekend. The core is loose on this yoke also and I'll need to fix it in position before I install it.

John

Hope the new one fixes the problem, you're so close to having a very nice picture!

I made a couple of attempts at making rosettes. The one on the left was done with a clear epoxy that is close to mahogany in color. I did spray it with brown mahogany lacquer.

The one on the right is made with a white paste epoxy. I think I'll try dying the epoxy to the right color, then give it a coat. Although it does kind of match the aging of the cabinet as is.

I need to trim the rosettes a bit to remove the excess epoxy.

The photo on the right shows the rosettes before coating.

John

I finally got around to swapping the yoke. Guess what, it was the yoke that was causing the focus issue! :banana:

I'll post some photos as soon as I get it finalized. In spite of being careful I managed to swap the two horizontal leads. I left them long in case I did something stupid like that. There's a bit of ringing that I hope clears up when I dress the leads.

The yoke that was in the set is the wrong yoke. It was a 100-0002 and the manual says that you cannot use it with an output choke that isn't center tapped without danger of breakdown in the yoke. That must be what happened to it. The manual warns that servicemen have been replacing the 100-0001 with the 100-0002 when they shouldn't.

The yoke I put in though is made just like the 100-0002. Moyer said that RAM says it can be used for either yoke. It came wired as though it was a 100-0001, but internally it's like the -0002.

Does anyone have a RAM catalog? I'd be interested in knowing what it says about a Y70F25 yoke. It's to replace a 100-0001 yoke in a 1-108 sylvania chassis.

I'd feel better about using it if I could find a center tapped choke to go along with it. Can anyone tell me cross reference numbers for a 241-0002 choke for this set? I've yet to figure out why they call it a choke instead of a transformer. :scratch2:

John

John,

Thats fantastic! Way to go. You may find the ringing is better when you swap the yoke leads, as often the yoke has a balancing capacitor across one of the two horizontal windings.

The Y10F25 yoke is speced at 25mH (H), 50mH (V), 27 ohms (H) and 60ohms (v). RAM does not list a replacement for the 241-0002 (flyback transformer, not a choke)

Thordarson, Stancor and Merit do not list a replacement. Must be an oddball flyback...?

The Thordarson cross ref. lists the 1-108 chassis as using a 113-0010 flyback, with a HVO-50 replacement. Is this a mistake in the Thordarson listing?

I was wondering about whether the balancing capacitor would do that, but it goes against my grain to think that a one-port passive network would behave that way. There must be enough stray capacitance to make another connection, turning it into a two-port. It does seem to behave as you said though. At least the original one did so I hope this one does too.

Thordarson didn't exactly make a mistake. The RF HV supplied sets don't fit neatly into the charts of Thordarson, RAM, and Merit. The 113-0010 is the RF HV transformer and is listed for the Horizontal output in the Merit catalogue also, even though that's not what it is.

I wouldn't call the 241-0002 a flyback because it doesn't use the retrace (flyback) to generate the HV. It looks just like a filament or audio transformer. All four of the manuals that I have for this set call it a choke, including the SAMS. I assuming that they have a reason to call it that. It hurts my head to think about that part of the schematic. :drool:

If you want to peruse the service manual you can see it at:
https://www.msu.edu/~yurkon/Sylvania_9-2_Sup1.pdf

Thanks for pointing out the 113-0010 being called a flyback. I now have cross-reference numbers to search for a spare. :thmbsp:

John

John, I am afraid I am a poor student. I had forgotten your Sylvania was one of those very interesting RF HV supply sets, and would use s separate transformer (choke?) to drive the horizontal coils. I also note on the schematic the yoke coils are wired in parallel, so my supposition about the balancing capacitor is probably not valid. But hopefully when you reverse the leads on the yoke, your ringing issues will get better.

Good thing you don't have troubles with the RF HV coil, as some of these don't have a replacement.

Any thought of making a wood one? If you could make a study enough die, (maybe with jb weld?) you could probably make one the same way the originals were made. Maybe cut a circular piece of mahogany, soak it in water for a while, and force your die over it, maybe in a vice, and let it sit until the wood dries?

That would be cool! I think I might try it.

John

The yoke that was in the set, and the replacement, are both made as you described with the coils in series and a capacitor across one coil. The 100-0002 yoke that is in the set was meant to be used in a center-tapped mode. The schematic shows the 100-0001 yoke where the windings are in parallel. That's the yoke that should have been in the set.

So, your comments really do apply.

I wonder why there are replacements for all of the other transformers and coils, but not the horizontal output thing?

John

John, if reversing the yoke leads does not work, I wonder if you could try rearranging the yoke to operate in parallel, without the balancing cap? How does the inductance of the replacement yoke compare with the original? What Sams Photofact is your set in?

These RF HV supply sets for the 10" and 12" CRTs were oddball sets even in their day, and I suspect the Thordarson/Merits/Stancors of the day did not consider it worthwhile to make these low volume parts.

The folder is number 11, set 96. I find the SAMS more difficult to read than the Sylvania or Wallace schematics.

The inductance of the RAM yoke is the same as the Sylvania. If I were to rewire the coils in parallel the resulting inductance would be somewhere between 1/4 to 1/2 the original inductance, depending on how much mutual inductance there is between the two.

I'm doing laundry tonight and when I do laundry I don't have access to the trap door to my basement so I won't get to try it tonight.

Roger Dreyfoos sent me some info from a RAM guide to yokes that is pretty interesting. It talks about residuals fields in some that need to be eliminated. I thought that was my problem, but now I think it's just a bad yoke to begin with, but no shorts.

It has an iron wire winding to form the core, that likely accounts for the low ring test. I don't think there's a short because both half coils test the same for inductance and number of rings. It probably doesn't shield well against the focus magnet which causes a rotation in the raster.

The yoke also appears to be deformed, I'm not sure why that is, but it is also off axis from the housing. The off axis problem is just the way it was assembled.

It also appears that it is not cosine wound, which doesn't help the focus either.

I'm still going to check it out with a hall probe, but using the digital compass on my watch suggests that the residual field is less than the earth's field. I don't think a residual field is the problem. If it turns out to be stronger than that, I might try degaussing it.

John

This is getting to be more involved than I expected.

I checked for residual magnetism in the yoke. The earth's field in Michigan should be about 0.57 Gauss. The field along any axis in the yoke was 0.5 Gauss or less so it doesn't appear to be magnetized. At least not enough to cause any problems.

The first photo shows the rear of the yoke. You can see the bottom h-coil is distorted. The second photo shows that it doesn't appear to be cosine wound. The third photo shows the ends of the coils not being perpendicular to the axix. I think these all add up to the bad focus issue.

If you look through the mounting slot you can see the iron wire that forms the core.

I shortened the leads on the yoke and corrected the reversed horizontal lead connection. The ringing is terrible.

After getting the right image by swapping the leads, the blue lead was not connected to the hot side as both the schematic says and the data sheets indicate. The horizontal output choke appears to at least had one lead lengthened. I don't think it's possible for them to have reversed the output leads and have it work at all.

As John Folsom mentioned, the coil that has the capacitor across it should be on the hot side, which it isn't now that I have the right image. I'll have to move it to the hot side and see how well it works.

The data sheet with the RAM yoke says that when they supply the network with the yoke it's not connected. In this yoke it was already connected. They also give instructions for balancing the yoke if there is still ringing after properly connecting the supplied network. If connecting the capacitor to the other coil half doesn't eliminate all the ringing I'll have to build their little "X" checker device. Just a variable resistor and capacitor in series.

I don't want to run the set while it's in this condition, so I'll take photos once I get it working better.

In spite of the ringing, the focus problem is still gone.

The yoke appears to have been made by Chicago. It looks just like their TY-1 yoke.

John

You can see the Chicago TY-1 here: http://www.bunkerofdoom.com/xfm/CHICAGO1954/004.jpg

and the similarity to the Sylvania 100-0002 is very strong.

The data is here: http://www.bunkerofdoom.com/xfm/CHICAGO1954/003.jpg

and the TY-1 is not cosine wound. It has an iron wire core just like the Sylvania. Not too surprising that focus was so touchy. Especially if they stretched the design to go from 53 degrees to 70 degrees.

John

I moved the balancing capacitor from its original position to the hot side of the yoke. I didn't take any before pictures because the ringing was so severe I was afraid it might damage something.

I haven't aligned the horizontal section or do any serious adjustment of the vertical. I was mainly interested in seeing whether the ringing would be reduced and if the focus would be good. The focus looks good, there is still a little bit of ringing.

The balancing cap in the original yoke was 47pf and the one in the RAM replacement is 68pf. I'll probably use a variable cap first to see what value works best.

Then I need to shim the yoke. For some reason it tilts down a little when it's mounted in the saddle.

Then I'll align the horizontal. That will take care of the curvature and reduce the flagging. There was always some flagging unless I was receiving an over the air broadcast. No chance of that now. There may be a minor problem in the sync separator.

John