So I have 26 Germanium Transistors from the 60's What now?

[JASO410]

So I am new too building effects and I just finished building my first box (Basic Audio Scarab Deluxe Fuzz) the other day. I recently acquired an old Akai 355 Reel to Reel unit for $50 from someone off Facebook Marketplace. The unit powers up and runs however the tape heads are damaged. I disassembled the unit and cleaned it out with an Air compressor. I am going to try and sell the mechanical parts and salvage all the old transistors. I powered the unit up the other day and plugged my guitar right into the mic inputs for the Preamp it sounded really nice when I turned it up slowly getting more and more distortion. So now I am looking for some input on what circuits would be the best use for the Various transistors. Thanks in advance for any and all suggestions! The following is the type of transistor followed by the quantity.
2SB443 X4
2SB75 X14
2SB370A X4
2SB338 X4

[PRR]

> plugged my guitar right into the mic inputs for the Preamp it sounded really nice when I turned it up slowly getting more and more distortion.

So don't monkey around. Re-box the ancient boards.

[Kevin Mitchell]

So don't monkey around.

I agree with PRR. If it already sounds good there's no reason to tear the boards apart. Just rehouse them. There are plenty of new-old-stock germaniums in the world for new builds. No need to transplant.

[RickL]

I'm just betting that all those transistors aren't being used in just the preamp. If you can figure out what part of the circuit is the preamp, I agree, keep that part and use the other transistors for something else.

If there really are 26 transistors in one preamp, I'd love to see the schematic  . Seems a waste to use all of them in one pedal. I bet you could get pretty close to the same sound with only half that number  .

Any chance the  preamp is by itself on one board or there is some kind of indication on the board of what parts make up the preamp?

[PRR]

> I'm just betting that all those transistors aren't being used in just the preamp. ....If there really are 26 transistors in one preamp, I'd love to see the schematic....

The clues are there. This may be an Akai X-355, schematic here. There are indeed 24 transistors on one page and I know where to look for another few. They do seem to be Germanium transistors--- that disagrees with my memory so I am glad I kept my mouth shut.

The line-up is a 4-stage record amp, a 4-stage play amp, and a 4-Q power amp (20 Watts!) for speaker. 12. All duplicated for stereo. 24. The tape bias is a 2-Q oscillator off-down-left. 26.


A healthy X-355 sells over $1k. Not something I would scavenge.

What still bothers me: in 1960 there were 30-cent fall-out transistors in those $9.95 pocket radios, and the 3-cent radio rejects used in early Ge pedals. OTOH the 1966 Akai would be using hi-spec $1 and $3 trannies, nearly as good as contemporary Silicon (which was just on the verge of consumer success). They may not have the reputed "mojo". Mature Ge amplifiers are just very-good, not what we want. Though JASO has shown that the mike preamp overloads musically. And why not? It is Just Another FuzzFace, plus a booster in front, a classic pedal topology.

[JASO410]

Thanks for all the feedback everyone glad this was able too generate some discussion. So I did end up going ahead and taking everything apart in accordance with the Service Manual and after I blew everything out with an Air compressor and got it all taken down I took the boards out and Started to just visually inspect them and for the most part they seemed alright. Nothing jumped out at me as a possible problem. So I started going through the boards with my DMM and comparing the values I was getting back from the Capacitors with the Values in the Schematic and the stated values on the capacitors and I did not find one cap that was even close to right. I checked my meter against known good components too be sure it wasn't some kind of technical Issue. It was not. I decided that based on the price I paid for the unit and the amount of work it would take to start to get it back to where I would like it too be I would rather just Scavenge through it and get what I could use out of it. There were already pieces missing from the Tape head area and the guy I got it from said he found it in an old abandon building he was tearing down to build a new home. I still have the full motor assembly in working order and all the included reel too reel parts. I am going to attempt to get a little $ back out of those parts. So I now have these transistors and a lot of other interesting knobs and 8 stereo jacks to do what I will with. I also found a couple paper and oil Capacitors (.02 and .01ufd) that I could stick in the tone pot of a passive guitar circuit. So for $50 I would call it a win. After I get done with my current project I am gonna find something cool to make out these components. I have been exploring various articles and YouTube video's about testing and matching the transistors. This is something I am not really familiar with so I will have some studying ahead of me. I understand how to read a datasheet and how to select an operating point by drawing a load line over a set of characteristic curves. My knowledge is really only based in tubes though so I will have to see how things change when working with transistors. Also in case anyone hasn't had the privilege of de-soldering something that is very old and musky from sitting in a building for a few decades it creates quite a terrible odor. I would suggest you do it in a garage or something. When my questions arise I shall come back to this lovely message board and request assistance.

[amptramp]

You could always build 13 FuzzFaxes.  Some of them may not work with the gains you have but that's one (bad) idea.