I picked this up off my regional Craigslist last week and thought I could do a quick restoration on it. However, when I took the back off tonight, I was greeted by the following: see pics. It looks like the yoke cover melted. This is as far as I've gotten.

As awful as that looks, it's possible the yoke may still be sound. Some covers were made of a miraculously cheesy plastic that self-destructs. I haven't seen one quite that bad before, but I have seen covers that were warped all to heck, with pieces falling off, etc.

I would withhold judgment for the time being. If the yoke turns out to be OK and you finish the remainder of the project, you can fashion a substitute cover later on.

Phil Nelson
Phil's Old Radios
http://antiqueradio.org/index.html

Is that a Philco style circuit module (top center of the picture)?
http://videokarma.org/attachment.php?attachmentid=184894&d=1416542902
Maybe Philco made this set for Sears...

I picked this up off my regional Craigslist last week and thought I could do a quick restoration on it. However, when I took the back off tonight, I was greeted by the following: see pics. It looks like the yoke cover melted. This is as far as I've gotten.

This was a common ocurrence with these yokes from the 50's & 60's. the material used to make this plastic like cover would deteriorate because of heat. the deflection yoke should be Ok. the problem with these plastic covers is that they also hold the centering rings in place. when the plastic cover deteriorates, you will not have any way to center the picture.

Is that a Philco style circuit module (top center of the picture)?
http://videokarma.org/attachment.php?attachmentid=184894&d=1416542902
Maybe Philco made this set for Sears...

Couplates are not specific to Philco. RCA, GE, Motorola, and others used them as well. This set looks like either a Warwick or Westinghouse to me.

Is that a Philco style circuit module (top center of the picture)?

Maybe Philco made this set for Sears...

Warwick Electronics of Chicago built this set.
Also, It Is not a "Philco" style circuit module, it is referred to as a "Encapsulated Circuit Module". there were two manufacturers that made these "E.C.M's" Centralab & Erie. the red modules were built by Centralab. these were used by many electronics manufacturers during the late fifties all the way up to the early seventies.
Both Centralab & Erie Would build these to manufacturers specifications. these were mainly resistor / capacitor circuits.

I've gotten the chassis out of the cabinet and cleaned up the mess. I'm wondering if one of the electrolytics shorted causing it to overheat. The 1st one pictured looks to be oozing its insides. It's a 5 section unit. haven't seen one that big before.
The 2nd electrolytic is one that I've never encountered before. It has a positive and negative at both ends. Normally, dual or multiple units share the ground.
Yes, this set does have couplates. I took a pic of the largest one, 15 components. I've watched bandersens Predicta restorations, and I've used his techniques to rebuild the couplates in a Philco Briefcase I recently restored. I'm also currently restoring a Predicta and will be rebuilding the couplates in it within a week or so. However, I hope I don't have to do that in this set. It has a 15unit, a 13 unit, and an 11 piece unit.

The 2nd electrolytic is one that I've never encountered before. It has a positive and negative at both ends. Normally, dual or multiple units share the ground.
It's actually two separate, unconnected caps. One is the doubler input cap, IIRC.
The first time I ever replace one of those, I (mistakenly) thought the red lead coming out one end went with the black lead coming out the other end, and proceeded to wire it accordingly. :eek:The dang set came on and worked, but with humungous hum bars and hourglassing.
I quickly corrected the goof.

I finished replacing all the electroltyics today aw well as the two rectifiers. I tried a power up with my Variac. Not very good results. Tubes lit but no sound no raster. Unfortunately this set is one of those where the chassis is a square with a cutout in the center for the CRT which stays in the cabinet as the yoke can be unplugged. To make test on the underside, I'll have to pull the yoke off the CRT and use my test CRT.

This is where having a test jig with a 'universal' yoke becomes rather convenient.

Well, after my last posting, I pulled the yoke off and hooked up to my 5" test CRT. I was rewarded with a raster but still no sound. Either something is amiss with the correct CRT in the cabinet or I turned up the wrong control for brightness when I made my initial power up. The controls aren't labeled, and I don't have a Sams for this set. Hooking up a signal gave me a pic, but I couldn't get the vertical to sync. Right now I'm recapping the sync board.

I'd like to know who built this set for Silvertone. I've already had one PC trace lift up on the sync board despite how careful I was. Even though the Predicta I'm also working on was a pain to recap, I didn't have 1 trace lift up during it's recap.

I'd like to know who built this set for Silvertone.

Warwick Electronics of Chicago built this set for sears.
i stated this in a earlier post.

I've got all of the capacitors replaced. That allowed me to lock in the vertical temporarily. The audio output transformer was open, so I replaced that. Now I have bad sync in both horizontal and vertical. I've subbed new sync tubes and replace the resistors in the sync circuit. It starts as a wavy pulling at the bottom of the screen hen travels up to the top. I cannot get that straightened out with the horiz hold. The vertical also loses sync too. This set is so simple, I can't figure out what I have overlooked.

With that symptom one always worries about a bad AGC resulting
in very compressed sync pulses. Scope the video.

Are you still using all of the original couplates? What circuits are they used in?

What's your video source? (Weak signal can cause weak sync and result in bad horizontal & vertical lock).

Phil Nelson
Phil's Old Radios
http://antiqueradio.org/index.html

Well, after my last posting, I pulled the yoke off and hooked up to my 5" test CRT. I was rewarded with a raster but still no sound. Either something is amiss with the correct CRT in the cabinet or I turned up the wrong control for brightness when I made my initial power up.

See if the heater inside of the original CRT is lighting up. Many sets have loose CRT plugs and the pins often had poor soldering from the get go, so things start moving around and you get intermittent connections. If the plug is loose, then you can move it gently and the heater will light up, or should. You can then re-solder the pins and re bond the plug to the glass with a suitable adhesive. CRT rebuilders' of late used a silicone based material, but I'm not sure exactly what it is.

Either way, you don't want to leave a loose plug that way because you will eventually break a conductor possibly at the glass and you will be really messed up....

Yes, it still has the original couplates. As of last night, I did not have a Sams, and had been trying to fix it blind. I was finally able to locate and order one. When it gets here, I'll work on the two couplates that appear to be in the sync area.

My Sams arrived today. The other night, I made some good progress. I foun that by putting slight pressure on the tunershaft, the pic and signal would clear up. Cleaning the tuner wafer switches didn't help, but I poked around and bent up one of the lugs on one of the wafer switches, and that seemed to clear up the issue.

During a 30 min bench test, the pic stayed pretty stable except it lost horiz sync twice. With the Sams here, I will start rebuilding the copulate in the Sync Coupling.

One question, one of the mica caps in this copulate is a 150pf10%. Then it says N1500. What would the 1500 stand for?

When you get the Sams, see if the set uses a 3-legged dual diode for the horiz AFC. If so, it probably is the cause of weak H sync and needs replacing.
It's in a little rectangular potted casing, and most common type is common-cathode (vs. series-connected).

This set doesn't have the 3 legged dual diode. After two bench tests tonight, I find that after about 10-15 min, it really loses horiz sync so much that it can't be corrected with the horiz hold control. I end up tweeking the horiz waveform slug.

Most of the parts in the horiz circuit are part of a 15 piece copulate, so I guess I will have to rebuild it as well as the sync copulate. This one uses two 8000pf caps as well as one 8200pf. All I can find are 8200s. I hope that will work. I'm going to start gathering parts tonight and see what I need to order.

I've been gathering the necessary parts to rebuild the couplates. I went ahead and rebuilt K5 which is the Horiz coupling. However after installing the new unit, still no change. When I 1st power it up, there is no horiz sync, and the horiz hold has to be turned about 5 times to sync it. AT this point, I have a full pic but jittery. Within about a min or 2, it loses sync, and the hold as to be retweeked about 1/3 turn every 10 seconds. Finally it gets to where it will not lock, and I have to touch the underside of the coil which is B1. At this point, the horiz hold has been rotated about 5 turns, and the pic does not fill the left side of the screen. After I shut it off and it cools down, I then have to put the hold back in it's original position to get a lock.

On the 6CG7, plate at pin 6 is about 190V, grid on pin 2 is about -30. Plate on pin 1 is about 155. Have tried another 6CG7. Voltages are ok on 12AV5G output. I have another output tube on order.

Look at the ID tag on the chassis, there's a number such as 528.xxxxxxx. The 528 (or other number) indicates manufacturer, 528 being Warwick.

Warwick built the lions share of Sears / Silvertone products until around the mid 1970's when Sears started using Japanese products.

Doug,
What is the exact model number for this set. I ask because when I look up
Sears-Silvertone in the Sam's index for 8106 , it lists Folder 35-20. Folder 35-20 is from the 1940's. The chassis number seems to be more important with Sears products.
Ed

Sorry about being so long in replying. My model is 8106, and that is what the sticker inside the cabinet says. My Sams 389-3 has it listed by the chassis, which is 528.50124. Both numbers are also on the back of the set.

I did make a little progress. R38, and 8200 ohm @ 2W was bad. I had replaced it earlier, but during a bench test, I had walked out of the room. When I got back the horiz was way off sync and squeeling, and that resistor was frying. It still checked good, so I left it in place not realizing that's when those horiz problems started. I put a new on in, and that kept the horiz from drifting ever few seconds.

It is still touchy and keeps losing sync, but I just have to bump the hold to correct it. Sound has also gotten weak. I tried doing an alignment on the audio using the instructions in the Sams, and that's didn't help. I then noticed when I would stick the alignment tool in the top of A8 (L15) the sound would get louder for a brief second.

A7/8 (L15) is a 4.5MC trap and also a Sound IF. It has two 33pf capacitors in parallel with it. I'm thinking maybe these have gone bad, so I've got some on order. The bottom slug on the coil is also stuck. I checked with Moyers, but so far they haven't found one yet.

My Sams only list the Silvertone number for the coil 10-120-1. Haven't been able to find a cross reference for that number yet.

The Sam's index I'm using has an error. The Silvertone 528.,,,
chassis shows up as 389-3. The 8106 number lists that other
Sam, folder 35-20.
Ed

Sams 389-3 is correct. You must have the same index I do because I had trouble finding it.

The Sams 35-20 covers an earlier Silvertone model 8106 radio/phono console. Sears reused numbers on many of their products.

My 33pf caps arrived today which are C35 and C37. I installed them across
L15, but that made no difference. Moyers has located me a Miller replacement for L15, and that should be here by the 1st of next week. Audio is still very weak, and horizontal still loses sync. The bottom slug on my L15 is stuck, so I'm hoping a new coil will help.

I like the Corvair convertible.....

.

I think I have fixed the audio. I started checking voltages, which were way off on the 5AQ5 audio output. R44, 560 ohm 1W going to pin 6 was open. Didn't have a new one, but I tacked in 2 units in series to give me around 570. Sound is much better but not perfect. I think when I get that new coil in, the sound will improve as I adjust it.

My L15 sound take off coil arrived today, and I have a couple of questions before I install it. The Miller replacement coil 1471-a has a resistor soldered across two lugs and also has two 4.7 caps.

The guy at Moyers, where I bought the coil, emailed me and said that his book said to delete them if my old coil doesn't use them. Therefore I will take out that resistor. However, the old coil uses two 33pf caps which I replaced. Should I keep the 4.7pf caps in the new coil or change them to the 33pf caps?

What does your new coil measure compared to the existing one?
Sams schemo shows 4 ohms, and if the new one measured the same as the old one, inductance is likely the same, so it may be better to use only the 33pF caps.

The only way the 4.7 pF would work is if the resonant frequency can be found within the tuning range of L15. The resonant frequency is likely 4.5 MC, so the sound is both amplified by the video amp tube AND taken off via L15 without loading down the video signal going to CRT cathode

Of course, you need to tune the primary and secondary slugs per the sams schematic, which may not have a method simpler than using a signal generator and oscilloscope.

I often did the sound take-off (secondary) by ear but always use a plastic hex tool.

I tried the coil with both the 4.7pf and the 33pf, and it worked better with the 33s, so I went with them. Sound is pretty good now, so I'm back to the horizontal.

As the set warms up, the horizontal loses sync several times. The horiz hold control is very touchy. The slightest movement of the slug causes a huge shift in the pic, and the lock range is very small.

Could this be caused by too much pic width? Here is why I am asking this. My set uses a width sleeve inside the yoke. When I started on this set, I found a piece of metallic tape inside the yoke for a width sleeve. Don't think it was original, and it was crumpled after I separated the yoke from the CRT. My CRT is one that stays in the cabinet, so I am using a test CRT. See pic for what was in my set vs the sleeve I am trying. New sleeve is wider.


I couldn't get that piece of tape back in the yoke properly, so I've been restoring the set with no sleeve meaning maxed width. Yesterday, I checked in my junk box and found a yoke with a width sleeve, so I tried that.
I could see a reduction in the width, but after a minute I heard some arching in the yoke, and I lost HV. Pulled out the new sleeve, and HV was restored. I thought maybe there is a bare spot on one of the yoke windings, so I have coated the windings with Corona dope and am waiting for it to cure.

I also replaced the horiz output tube, and no change.

You may be onto something.
Try putting an AM radio in proximity to areas of suspected arcing.
Arcing of anything will usually cause a loss of horizontal sync.

The next thing to look at for your sync issue requires an oscilloscope so you can see if sync pulses are making it from the video amp through the sync sep 6EB8 and amp tube 5U8 to the 6CG7. The K-dots all over the place show the resistors and capacitors in the Kluster-packs (AKA integrators) and any one of those could cause your issue. Check those tube voltages....

Not too much luck today with it. After the corona dope cured, I reinserted the width sleeve and it immediately started arching. I had used the lighter amber corona dope to coat the yoke windings, but I have not used the thicker orange stuff, and it's curing now.

I also discovered something else. I was watching bandersen's series on Zenith bug eye sets last night. In that series, he encounters width sleeves for the 1st time. He describes them and mentions the spring clip that holds them in place with a ground wire. I hadn't don't that, so I went back out to the parts chasses where I got that width sleeve out of a yoke, and sure enough, there was that grounding clip. However installing it made no difference. Still arching.

Continuing to watch his series on the Zenith sets, I noticed his yoke had a cardboard sleeve insulating the yoke windings. So is the correct set up: yoke, cardboard sleeve, then width sleeve inside the cardboard b ut still against the tube neck, or should the width sleeve be directly in contact with the woke windings?

... should the width sleeve be directly in contact with the woke windings?
:eek: Nein! Nyet! By all means insulate it with something more substantial than spray-on dope if there's enough clearance.

Just a thought, have we checked the horizontal hold pot for tin whiskers? Even if it ohms out correctly, I'd sneak a peek inside and clean it good. I had a tough dog once with the same indication you have, and turned out to be that simple.

did you check R36?

Ok, here is where I am at. I decided to take the full size CRT out of the cabinet and try it. With the width sleeve in, I'm getting too much width on the right side and not enough on the left. Centering rings won't compensate for this. See pic.

Horizontal is still messed up. First off, it's not a pot. It's a coil with a top slug for find adjustment and a bottom slug for course adjustment. I'm going to check with Moyers tomorrow to see if they have a replacement. All my Sams has is the original Silvertone # 10-121-1.

Dave, I had replaced R36 earlier, but the other night decided to experiment and tried a 6800 ohm, 10K, and 15K. All that happened was I had to turn the hold to a different frequency, and it was still unstable.

I checked all the voltages on the 6CG7, and they are normal. I then moved back to the sync. V5 Sync Sep 6BH8 SB 7.5V on pin 3, and I have around 25.
Also on the Sync Amp 5U8, Pin 8 SB 9.5, and I have around 25V also.

I have rebuilt K1, K3, & K5. K2 seems to be tied into these problem areas. Perhaps I should rebuild K2 next.

Doug, sorry to not being able to help you out about your width issue, but one thing in your message popped out to my eyes: the 2 adjustments on the horizontal coil are NOT for fine/coarse adjustment!

This is the typical synchroguide horizontal oscillator and, for proper operation, it should be set in the following way: first, you set the horizontal hold pot at half of it's travel, then you short out C48 (the .01uF capacitor in parallel with the horizontal waveform coil) and, with the upper slug, you should sync the image on the screen. Then you remove the short on C48 and, with an oscilloscope connected at the junction of the 2 coils, you should obtain a combined waveform composed of a sawtooth and a sinewave, just like this one: http://www.rfcafe.com/references/electronics-world/images/wayward-capacitor-woes-oct-1960-electronics-world-3.jpg. You should pay attention that the "tip" and the "shoulder" of the sine part of this waveform are at the same height.
If this particular oscillator is not properly aligned, it could cause every kind of strange behaviour in a TV set.

If you already knew that, then I apologize having stated the obvious :thmbsp:

Cheers

Giulio

Edit1: I rechecked the schematic, your TV doesn't have a horizontal hold pot, so disregard this 1st step
Edit2: The place to put the 'scope probe is called "G" on the schematic you provided. If, after tweaking the slugs, you still have instability, you should check the waveforms coming from the sync separator, if these have the correct shape and amplitude, then keep in mind that all the mica capacitors in the hor AFC/oscillator circuit are suspect, as these are under lot of electrical stress and can definitely fail. These capacitors MUST be perfect and NO leakage!
Note3: Your R36 (or R38?), the 8,2K is the screen grid dropper for the Hor. output tube. Changing it's value affects the frequency because the B+ voltage for the hor oscillator is derived from the B+ boosted. Changing the resistor does in fact have an effect on the B+ boosted source because it lowers or raises the power the 12AV5 gives out.

I'm back on this again and really need some help. I've been looking for a yoke, and Moyers found a Thordarson Y97 which is supposed to be an exact replacement for mine, Silvertone 80-2-4.

When it arrived today, the instructions said to take out the two 220 ohm resistors in parallel with the 560 ohm resistors to duplicate the original. When I took the cover off the yoke, which is stamped Y97, I only found two 150 ohm resistors.

trying to compare the instructions with my original Sams even got me more confused. My original yoke only has 3 wires going to the socket, while this one has 5.

I've enclosed a scan of the instructions, the yoke section of my Sams, and a pic I took of the replacement yoke.

Thanks for any help.
Doug

Hello Doug, please no panic, the solution to your issue is simpler than you think! :thmbsp:

About the resistors value and the instruction to desolder the two 220 Ohm, then the more logical conclusion I came to is that the original parallel of 220ohm and 560 ohm gives a final value of 157ohm, pretty close to the 150 ohm you found. The best way to fix this problem is to simply discard the 150 ohm in your yoke and solder a couple of 560 ohm ones in their place.

To fix your other problem, first thing to do is to disconnect the orange wire coming from your new yoke, this is not required in your TV. I would simply snip it from the tab inside your new unit and pull the now "dead" wire away. So, now we are at 4 wires instead of the original 5, yikes!! This, again, is very simple to take care of, simply unite the Yellow and black wires and consider it a single wire. Again, me being me, I would make a jumper inside the yoke body and exit from it with our 3 wires.

Please, pay attention to the replacement yoke plug pinout, as drawn, it is wrong! (as an example, the red wire, called pin#7 does in fact go to pin 8 of the plug, so, unless i'm barking up the wrong tree, something is amiss!)

Also, if your new yoke does not have the series RC cell (68pF 3000V + 1000ohms) across half of the horizontal deflection coils, you'll have to transplant it from your old unit.

I hope I was of any help to you, not a pain, unfortunately my english is not too good

Cheers

Giulio

A favorite practice of mine when subbing yokes is to do the initial connections with clip leads so if I have it wrong I can power it off reconfigure the connections and try again before the tube heaters go completely dark...

After I panicked last night, I sat down an reread the instructions and figured it out, but thanks for the help.

Now I have a new issue. I've got the new yoke installed and did a power up. I have no Hi voltage. Checking voltages on the 6CG7 gives good readings on both plates, pin 6 and 1. I don't have any negative voltages on pins 2, 7, 8.
High voltages probe shows nothing on CRT anode, plate of 12AV5, or pin e of Damper.

Good afternoon Doug,

You are missing your negative voltages because the horizontal oscillator is not working, also, your High voltage is missing because of this!
As a quick check, please control the continuity of the 50 Ohm part of coil L22 and that you obtain about 490Kohm between 6CG7's pin 2 and ground. If these 2 tests do not point to a "smoking gun", I'll suggest you some other tests to perform to help straight out your problem.

I really doubt it is the 6CG7 itself, as it is a reliable tube, but did you try a spare tube?

Cheers

Giulio

Hey, the tests were way off, so I replaced C47. Still nothing, so I tried another 6CG7 tube. That brought everything back including HV. Didin't think it would be as simple as a tube!

Thanks for the help.
Doug

When I got this set, the original yoke cover had disintegrated leaving a black powder over the chassis. Also missing was the width sleeve. I found another width sleeve, and I know I need an insulator like fish paper between the sleeve and the yoke.

I just got some fish paper. Do cut the paper the size of the width sleeve and glue them together, or do I encircle the yoke completely with the fish paper?
Thanks

Ok, I've finally got the yoke working right with the width sleeve and yoke cover. However I still have unstable horizontal which has plagued me from the start. I turned the set on tonight for about 30 min, and a new problem arose. The sound became distorted, and a hum bar appeared which started at the bottom of the screen them moved towards the top then started again at the bottom. Tried new tuner tubes, but that had no effect.

here are two pics.

After a hiatus, I'm back on this again. The original CRT was very weak, so I just replaced it. The new CRT allows me the back off the contrast, which makes the horizontal more stable. I gave it a bench test tonight for about 45 min. I had to sync the horizontal when I first turned it on. After awhile, the pic shifted to the left which can be seen in the pic. Also, I have several black vertical bars on the left of the screen. This set has no horiz drive to back off of. Just the horizontal hold coarse and fine slugs. Also some smearing on the right of the screen.