1951 Silvertone 1342 Amplifier [Build]

Today, I took apart the guitar amplifier I bought last month.  It's a 1951 Silvertone, model 1342, that I honestly believe belongs in a museum.  So, because I am who I am, I took it apart!

The neat thing is that there is no schematic of this amp online, no real information on it other than anecdotal stuff by old-timers and collectors.  For the most part, it has fallen through the cracks in history and into my hands via a very fun, very interesting older gentleman by the name of Dash who lives in the east village, still bikes around at the spry age of 60-something, and invited me to jam with him whenever I get a chance.  Cool cat, for sure, and yet another awesome Craigslist experience.

This amp cost $65 new when built and the design only lasted two years, for reasons unknown to me.  I'm in the process of putting the 100% original components through their paces and replacing what needs to be replaced in order to keep the amp and the player safe from harm. Here's a list of things I'm going to do (things completed are in bold):

1.  Replace 2-prong power cord with properly grounded 3-prong cord
2.  Clean potentiometers, jacks, speaker, grille, and cabinet.  Make sure all solder connections are solid.
3.  measure resistor drift (this happens over time, esp. in older, cruder resistors)
4.  replace all electrolytic capacitors (these can leak and explode and actually have about a 30-year shelf-life)
5.  properly shield the chassis from Radio Frequency (RF) interference
6.  Replace speaker baffle
7.  Replace speaker for personal use

Just for funsies, here's a link to a site that specializes in vintage Silvertone stuff

Here are some photos of the amp and some explanations of what the crap goes on inside one of these things:

You can't really see it, but it's slightly trapezoidal.  The explanation in the catalog is that this "improves airflow."  But that's pretty much bullshit.  Note how clean the contact paper is.  This thing was babied.

panel from left to right:  2x instrument jacks, microphone jack (unbalanced), instrument volume, microphone volume, tone/on/off, fuse, pilot lamp.

The speaker has a tiny ALNICO magnet (that stands for Aluminum, Nickel, Cobalt) and pushes out about 10-20 watts peak.  It's not very efficient, which leads to some beautiful break-up as you turn up the volume.

Tubes, from left to right:  1273, 6SL7GT, 2x 6V6GT, 5Y3GT.  The two metal cases behind the tubes are multi-capacitor cans with several VERY high voltage capacitors whose function was originally to filter the electricity as it comes from the wall.  As they get old, they can burn up and explode, causing the big metal power transformer (to the right behind the tubes) to burn up.  At that point the amp is worthless.

If you've ever seen a modern amplifier, you know that this is nothing like those.  This is a true point-to-point design, without any support or organizing boards.  All these components are discreet, there is not a single transistor or integrated circuit.  That makes it fun, but the disorganization makes it harder to work on.

This is the full tear-down.  Note the plywood speaker baffle, which is honestly the only bad part about this amp.  It's thin, flimsy, and the screw holes have started to split.  I will replace this if I keep the amp, which is still up in the air.

This is the seriously awesome schematic.  The Silvertone brand was part of the Sears Roebuck company.  They also made guitars, harmonicas, and other various instruments.  Kinda cool.