Sears Silvertone Solid State 150 (Model 1465)

[jHill]

Hello all, I'm new to the forum, but I'm glad I found it because this seems like a place where I can find some real answers. I am the proud owner of a Sears Silvertone Solid State 150 (Model 1465). I just recently opened up the head to clean it (I don't think it had been cleaned since it was manufactured). This amp was a gift to me from my dad when I was about 17 and I have kept it ever since. It sat in storage for some time (about a year) where it wasn't used. I plugged it in and it sounded as good as ever. Then I took the head out of its old casing and blew out a LOT of dust that has been building since I'd guess around 1968, haha.

Anyway, this amp used to be notoriously loud, to the point where there was no way I could turn the volume knob above 4. After blowing it out I took some q-tips and isopropyl alcohol and cleaned off some of the gunk that had built up on the back of the volume pots. I made sure that the q-tips were not dripping but only damp, and what came off of the back was an unbelievable sight. There was a LOT of filth that had built up on the back where you could see the rod come out of the back of the pot, there was literally stuff falling off of them just from turning the knobs on the front and making that rod on the rear of the pot spin. (sorry if I'm using incorrect terminology, I'm totally green here).

After cleaning them, I replaced the power cable because the old one had a very large area of wire exposed. I installed an 18AWG SVT cable with a ground (the old wire did not have a ground, it was just an old 2 prong plug), attaching the black wire to an existing black wire where the old cable had been soldered in, and the white end attached to the 5A fuse housing that holds the 5A cylindrical fuse. I then attached the ground wire to the metal chassis that the circuit board is mounted to (the board is held away from the metal by plastic spacers.) Then I stalled a 1/2" bushing in the hole to protect the cable.

Well, after putting everything back together and putting in a brand new fuse, I turned it on, with no unexpected problems. No pops or crazy noises, but now when I turn the volume up, it responds up until about the 1 -2 mark on the knob, but then the volume stops climbing, no matter how far I turn the knob. Even at level 10, it sounds only as loud as about 2. It is not distorted or making pops or cracks, and the hiss doesn't sound any different than it ever has with this amp, mainly just normal sounding line noise I hear with any amp. This amp has two inputs per channel, and two channels. I tried all of the inputs and both channels, and I found no difference per input, and also the second channel is doing the exact same thing.

So there you have it, just trying to figure out where the monster that used to live in this thing went... I'd like it to come back soon. Solutions or suggestions welcome. Thanks so much for reading.

[J M Fahey]

Pots start scratching from dust and grime in only a few months .
I would have expected 40 years old pots, seeing little or no use, would be absolutely useless.
Try to get the schematic just to play it safe and replace all pots, probably jacks and switches too.
Everything metallic corrodes some way or another and dust+grease grinds pot tracks.
A very small price to pay for restoring such a fine amp to full glory.
And yes, a true 100W RMS amp into 2 good ¿Jensen? speakers IS loud, even today.

[jHill]

Thanks so much for the info! I'm learning, I'm actually glad that I have a little project like this to work on. The only problem I'm having is locating a schematic for this particular model. I looked in the link listed on this site for the silvertone schems, but my amp is not listed. Also, when I do locate one, where would I go about buying all the new parts? Pots, jacks, switches, etc....

I'm excited to learn more about this, I have always been curious about how my music equipment works, I'm glad I found this site to guide me. Thanks again.

P.S. I was fortunate to have a pair of 10" Celestion Greenbacks that I installed in the original cab. They sound great. I'm running an American Strat through it. The only thing that saddens me is that the mesh grill on the front of the cab was apparently replaced with a black one and they removed the plate in the lower corner that read silvertone on it. Oh well, at least I have a good majority of this historic setup.

[teemuk]

I don't see why you would neccessarily need a schematic, it can speed up things but things can be fixed without one too. The potentiometers likely have markings on their back indicating the resistance and the taper function, you can also try verifying them with a multimeter. In case of switches, judging by the photo, I think there aren't any except for the mains switch, which is most likely still ok. The jacks, they can be switching type but they likely aren't encased like many modern ones so you should be able to see if there's an internal switch moving inside them when you insert a plug. Multimeter's resistance test will tell the rest about the switching scheme.

[jHill]

Ok, I took everything back apart, and took some shots of the pots that are in the amp. I have looked all over the internet for these, unsuccessfully. Then again, I may be looking in all the wrong places. Here they are.





So there they are. The numbers on the backs of these read "45-2176 15k 6629." The one in the picture has "6611" on the end, but is the only one that does, and it controls the BASS on the first channel. The BASS control on the second channel has a "6629" as well, not sure why they're different or if it makes a difference at all.

6629 goes for 8 of the 11 pots that are in the amp.
6611 goes for 1 of the 11.

The other two are as follows: 41-2175 1 MEC DJ F6 (These two are the pots controlling the tremelo and reverb functions)

I'll continue to look for them, if you know of a place where I can get them, please let me know. Thanks again for all the help to both Teemuk and J M Mahey. I'm ready to knock this thing out.  :trouble

[bry melvin]

musicparts.com has that schematic plus other info

I quote:

Sears 1465 Silvertone (Chassis 185.12011) Amplifier Service Manual
Contents: Schematics, Controls, Functions & Theory of Operation, Voltage Check Points, Front / Rear Panel Illustrations, PC Board Layout, Speaker Wiring Diagram, Parts List (D1960's) ($15)

I've gotten several hard to find schematics from them. This should give you the values so you can substitute!

[bry melvin]

Just another thought the reverb and tremolo pots MAY be different because SOME tremolo pots are reverse pots on some amps (reverse logarithmic) ...at least in vintage tube amps they are.

[J M Fahey]

From what I see your pots can be descr1bed as "value in ohms" - "maybe taper" - "maybe some mechanical code (winged/P.C. mount/shaft length/shape/etc." - "manufacturer code" - "manufacturing date" , not neccessarily all or in that order.
All those "extra" numbers maybe are not that important to you as an end user but help (a lot) inventory and ordering systems in factories, specially big ones such as golden era Silvertone.
As a side thought, consider the millions of Americans who built high quality amplifiers, instruments, TV sers, cars, jeans, tools, whatever, who now lost jobs to overseas cheap exploited labor.
Check this pot dating info:
http://www.triodeel.com/eiacode.htm
Back to the pots: from all the numbers I can guess some:
Th"45-2176 15k 6629." =
45 = *maybe* an old manufacturer  *or*
45-2176= ¿an internal part number?
15K= definitely the ohmic value
6629= week 29 of 1966 (compatible with a '68 amplifier)
6629 goes for 8 of the 11 pots that are in the amp.
6611 goes for 1 of the 11.<-- date codes.

The other two are as follows: 41-2175 1 MEC DJ F6
41-2175= probably internal part number, as above
1MEC = probably 1 Meg(ohm)
DJ F6 = probably an "encoded" date number, to avoid users complaining "my new (1968) amplifier has an old (1966) part", which is ridiculous (for us).
In short, your pots are original (you already knew that), the value can be read, although not the taper , they are probably 25mm (1") size, you measure them, with printed circuit mount legs, measure their length too, and have side wings for strength, which you will probably not get.
In that case I usually grind pot sides slightly and solder a piece of stiff 0.50 mm brass wire joining case to PCB. Not the same as a dedicated side wing, but helps.
*IF* you spend those meager $15 on the schematic, you will read pot values accurately there, have it for future maintenance, and even popst it here (hint, hint) to help fellow Forum members. :tu:
I sure would love to learn how they pulled 150W out of only two TO3 devices. I make amplifiers since 1968 and king of the hill was 2N3055, good for 100W, period.
Good luck.

[amp_tramp]

If I understand you correctly, you said the amp was fine after being stored but not fine after you opened & cleaned it, etc.  So, you need to check the work you did.  Cleaning the cases of the pots wasn't likely to cause any problems.  Perhaps you accidently bent a part over and its shorting out to another part, or to the chassis.  Do a close visual inspection.  Undo any other changes you made, for instance, remove the ground you added and see if that makes any difference.

I'm not sure replacing all the pots will make a difference, lots of old pots still work great.  If they are dirty, many clean up fine with a good cleaner.  Use one made for use on pots and that includes a lubricant to help them last as long as possible.

If the amp lost volume while it was in storage, you might be looking for a bad capacitor.  Electrolytics (like the little blue cans in your photos with a lead out of each end) especially don't age well.  Neither do some old paper types, but that amp might not have any any of those, (I don't see any in the photos).  Note that electrolytics have a positive and a negative end, be careful not to get them backwards.

Another possibility is that you damaged a part even though it was off while you were working on it (it was off then, I hope).  Sometimes there is enough energy stored in the circuits to allow that to happen if you accidentally shorted something out moving things around.  In this case, probably a transistor.

These old Silvertones can really sound quite good, and a lot of people still love them.  I hope you can get it going.