Lafayette Stereo-10
I got this old stereo amplifier from a flea market and only paid a buck for it. It's a low wattage amp and uses two seperate pots for the stereo channels which is super weird. I wanted to give this thing to a friend so my goal in working on it was to make sure it would be reliable.
The inspection date on the bottom says this thing was made in the 60's. I'm expecting some germainium transistors.
This amp is very servicable. I will definitley be changing out the filter caps in the power supply.
You can see the germainuim transistors that are bolted to the chasis for heat dissapation. Before doing anything, I took the values down for all the electrolytic caps in the amp and ordered replacements for the ones that I didn't have on hand. I want this amp to be reliable and there aren't that many electrolytics so I figured I'd just replace them all.
Here's a shot of the replacement caps soldered into the power supply section. The alligator clips are going to dummy load resistors for each channel so I can test the amp with a signal generator.
This is my setup for testing the amp. I was looking at both channels on an oscilloscope using a 1kHz tone. Both channels looked good through the aux and phono inputs and could be driven pretty hard before showing distortion.
Since I already had replacements for them, I went ahead and replaced all of the electrolytic caps in the amplifier circuit. Heres a shot of the phono preamp before.
And here's the preamp after replacement. I used some Nichicon audio caps.
While resoldering a cap on the main amplifier board, I noticed a resistor that was soldered on the underside of the PCB that had split in half.
I used two 1/4 Watt resistors in parallel to be safe because I don't know what kind of current this resistor needs to carry but I doubt it would be over 1/2 a Watt.
Here's a shot of the board after re-capping.
The board is a little more crowded now because I used capacitors with a higher voltage rating.
All the old caps
The last step was using contact cleaner on all of the pots and switches and then putting it all back together.