My next restoration victim, Silvertone
 

Uh, I mean patient...

A 1957 or 58 Sears Silvertone Portable, 17" I think, model PC 7102R

It's in pretty good shape, knobs have the white mold and there's a bit of rust in the bottom of the cabinet but nothing bad, knobs are soaking in soapy water as I type.

Silvertone sets seem to be another victim of the dust rag, this one, like so many, have bits of the Silvertone Script broken off, this reads more like
Cilver one.

Set powers up to a strong AC hum and a horizontal line across the screen so basically it just needs recapped.

The date code on the CRT is the 30th week of 1957 so I guess this could have been sold in 57 or 58 depending on how quickly it was sold.
The 312 EIA code would mean the CRT was made by Sylvania, it's branded Silvertone however.

There's some red inspection paint on the Ion trap and CRT neck that shows the trap has probably never been removed.

Pulled it apart to inspect, decal says it's a Deluxe model but it looks pretty stripped down to me, minimal series string chassis, pitifully low tube count, I don't even see a damper? it does feature (if feature is the right word) two selenium rectifiers though.

Does anyone know who built this thing, Wells Gardner, Muntz?

The set was unusually heavy for a hot chassis, part of the reason is it uses a real 1/4" thick safety glass!

There's a date stamped inside the cabinet but as luck would have it the year is obscured.

The tubes are dated middle of 57 so it seems like it should be Dec 57 but that last digit is clearly not a 7, possibly an 8 but that would mean more than a years difference between the tube dates and the final assembly?

Maybe it's Dec 29 1956, a 6 is plausible based on what can be seen, possibly the date the cabinet was made and not the final assembly date?

It would make more sense to have the cabinet sitting around for six months waiting for the chassis.

This thing has an odd Circuit breaker/resistor assembly mounted on the inside of the back, AC comes in directly from the cord to this assembly then to the chassis.

Hi Eric, What is the chassis I.D. number? It does look like a Warrick built set. A prefix of 528.xx,529.xx or 456.xx are Warrick sourced. all the best,Tom

It looks like a Warwick sourced set, but the model number seems a little different.
I understand, Warwick had a plant in California and it was probably built there. The damper is the octal tube above the HV cage.
The large resister on the plate with the CB is the heater dropper.

I had a big 24" set with what looked like almost the same chassis.

Eric, have one of those and have given up on it. I never could get the horizontal to stabilize. I rebuilt all the couplings and changed the horizontal frequency coil and finally set it I the shed. Maybe I will try again sometime.
I assume yours has those large copulate with about 13 parts per unit.
Keep us informed. I will follow this thread closely.

Your's is a later model, that uses PC boards.

When you go to recap that beast, don't make the same mistake I did back in the day. On the first one I got ahold of, that double-ended electrolytic needed replacing. The replacement had a red wire and a black wire coming out each end.
I (mistakenly) assumed "aha, each red wire goes with the black wire at the other end", and proceeded to wire it accordingly.
The set actually came on, but with gawdawful hum bars. Then after correcting the goof it worked fine and nothing got smoked.

I tested all the tubes, only one was bad.

The 4BQ7 in the tuner showed a short, there's a note from a tech on inside of the cabinet that says "4BS8=4BQ7" and sure enough, the tube chart shows a 4BS8 in that location.
I found a NOS 4BS8 to replace it but it too shows a slight short on my tester, possibly my tester is just wrong on this one, in any case I'm going to use the 4BS8 since that's what it originally came with.

I also gave the chassis a bath, it was filthy and some of the plated parts had that green Cadmium corrosion on them, I used some spray cleaner and a wire brush on the corroded parts, followed by a hot water bath, I avoided getting the flyback soaking wet. After that it went in the oven on the lowest setting of 170 for 15 minutes and then left it in another 30 minutes with the oven off, it came out sparkling clean!

I found this model in the 1956 Sears Wishbook catalog on http://www.wishbookweb.com/

Turns out the cabinet is Aluminum so what I thought was rust inside must just be 60 years of dirt and whatnot.

The tube shields are unusual on this set, I couldn't figure out how to remove them at first. They are two piece thin spring steel attached to the chassis, each half wraps two thirds of the way around the tube making a nice tight fit all around, you simply have to pull them apart and they open up exposing the tube, a really ingenious idea since it makes a good connection to the chassis and it holds the tube firmly in place.

Oh, and I found the Damper tube, hiding at the very bottom under the sweep tube, it's the usual 12AX4, you can just see the socket peeking out bottom right.

I pulled the Sams on the beauty and it shows the damper tube is beneath the horiz output tube, a 12AX4.
The set in question, seems a lot different, than the set shown in the Sams.

Can you give me the Sams number? I don't think I have one for it and have been having problems looking it up by model number

This set was repaired sometime in the early 60's, there's a five! section Sprague Atom installed with a 1960 date code.

If only I could time travel back and order another one of those.

Hi Tom, the chassis # is 456-50084

Hi Eric, Your Sams is 339-13 from 12/1956. With Sears look up for photo fact by chassis number and look under Sears not Silvertone.All the best,Tom

The tube shields were a U/L requirement, where they couldn't be removed and left laying inside the cabinet to contact the chassis and energize the metal cabinet.
BTW, the middle set, shown in the wish book, the one with the knobs and the dopey handle on the side is shown in the movie, "Godfather I". :thmbsp:

Thanks, I have one ordered.

I've made quite a lot of progress on this one.

Got all the caps replaced, for the five section cardboard electrolytic I just removed it and installed the individual caps where the original leads connected so they are scattered all over the chassis, as luck would have it there was a ground point within reach of all of them.

The other cardboard tube contained two individual metal can caps, I just removed those and soldered the wires directly to the new caps and stuck them inside the tube in it's original location, I'll squirt some Silicone Rubber inside to hold them in place.

The rest were just common value tubular caps, I replaced them all with the usual yellow axials.

I ordered a supply of caps from Sals Capacitor Corner, they were cheap and got here fast, they look like very good quality and have long leads on them, this was the first time I ordered from him but I will be going back next time. http://www.tuberadios.com/capacitors/

The Electrolytics came from Mouser.

the set is making a great picture but the sound is nearly inaudible, seems like that's usually the case, tweaking the detector didn't seem to make any difference but I didn't really get into it tonight because I'm tired of working on it for now. :yes:

the Vertical Lin control is either damaged or dirty, the vertical is a flat line up to a point then it pops up to a full raster, I'm able to get decent linearity but I'll probably have to fix it to get it perfect.

Found the problem with the sound, it was just a dirty socket on the ratio detector/af amp, now it plays nice and loud!

Found out this Sams isn't entirely correct for this chassis either, a couple of the tubes are different, including the ratio detector/af amp.

I had to use the tube chart in the cabinet to figure out what tubes were supposed to be in it.

the next thing to do is replace the vertical hold and linearity controls, the linearity is shot, it's dead past a certain point and I can't get the vertical perfect.

It's a double pot in a single case, the Sams lists two different part numbers for replacing it. I suppose I could just use a couple pots of the correct value.

Question, Sams says the linearity is 6000 ohms with a 1000 ohm stop, the Height is eight meg with a one meg stop.
Where would you even find an 8 meg pot?

I think those holes punched in the back of the controls are probably the stops?

One interesting thing happened, the vertical output tube died, I shut it off to do something and when I turned it back on no vertical, the amp meter I have in line with the Variac was showing almost an amp of current and one heater in the tube was glowing much brighter than normal.
I found another 6CM7 and was back in business.

I had been running the set with the Variac cranked up higher than normal trying to bring the B+ up a bit, (the Selenium rectifiers may be getting weak), possibly the extra voltage killed an already marginal (original Silvertone) tube.

For the linearity control, I wonder why you couldn't use a 5K pot with a 1k resistor is series? Seems like that would be a functional equivalent. 8 meg is going to be tough, other than another parts set. 10 meg are out there. http://www.allelectronics.com/make-a...ear-pot/1.html

edit - just found this. http://www.ebay.com/itm/1-Clarostat-...UAAOSwKPNTyrQw

If there's room to mount these type pots, I'd try it with a 1 meg resistor is series.

That sounds like a good idea.
the chassis already has the mounting slots for individual pots so all I need to do is get a couple of the right, or close enough values.

I have a box full of Pots I bought off eBay so I'll go through those first, doubt there's an 8 meg in there but I might find something to replace the 6k.

Okay, I've come up with an easy solution.

They only used one side of the pot, the side without the stop, circuit is hooked to the center tap, outer leg was hooked to ground through a 1k resistor.

I moved the resistor to the other outer leg and it worked but without enough range, then I realized that was the side with the 1k stop, so with the resistor it was 2k, took the resistor out and hooked the leg directly to the chassis and it works fine, the bad spot is outside the area needed to get the linearity right, the control works backwards of course but that's a minor issue.

The vertical controls have extenders on them so they stick out the back, accessible to the user, possibly there was a vertical issue at some point, or they were just obsessive about getting the picture perfect and they wore out the pot fiddling with it?

Sounds like a good workaround. So you can do the same with the 8 meg, or will the stop mess things up? Possibly you can eliminate the stop.

The 8 meg pot is okay, I was only going to replace it because it's a combined control.

I'm going to declare this one done!

I thought I was done a couple days ago but then I noticed a little vertical shrinkage and flagging at the top of the screen, increasing the AC voltage stopped all this.

I had noticed the B+ was about 20 volts low because the Selenium Rectifiers were getting tired, I was going to let it slide until these problems popped up.

With some help from the people over at the A.R.F. I ripped them out and replaced them with Diodes, after doing that I had to increase the size of the resistor feeding them because the B+ was 20 volts too high, then I had to install some snubber diodes across the caps to stop the hum bars caused by the diodes, it was a bit of work but after getting it all worked out the set looks great!

According the the 1956 Sears catalog, this was Sears Best portable, it's a cheap, series string set with a fairly low tube count but it works as well or better as some of the Deluxe RCA Portables I've worked on, and it's a heck of a lot easier to work on!

Looks good! I still love the soft B/W picture on these old sets better than the super-bright overly "crisp" HD flat-screens of today. Watching a classic movie like Double Indemnity or a Honeymooners episode is a totally different experience on these old sets.

That looks great. Horizontal and vertical linearity looks about perfect. And you sparked quite a technical discussion over on the ARF. :)