stereson wildcat bass amp

[teemuk]

I wouldn't advice going overboard with the capacitance. Too much of it and the inrush will begin to blow fuses. Use caps that have equal or higher voltage rating than the caps you are replacing. For capacitance, get something that's in the ballpark of the old part.

If the old one was, say 500uF, don't use a 1000uF cap but maybe a 470uF, 520uF, or 560uF.

As for unobtanium germanium transistors. If they die replace with silicon and reconfigure the bias circuit. You probably won't notice much difference except for a huge improvement in reliability. R.G. Keen has written some good stuff about this issue concerning Thomas Organ solid-state Vox amplifiers. The good news: The information is for most parts interchangeable since you likely find a very similar design from these amps.

Schematics and layouts..? Heck, if you really need them just spend a few hours to sketch them out. With these kinds of amps it's still humanly possible without a microscope and without having to spend weeks into the process. If you choose to take that path then post the sketches here (or to the Internet in general) so that in the future there actually will be some information and technical documentary about these amps to help other guys like you.

[Tonyrhs13]

yea i think im going to gut it and build a fender tube amp into the head, maybe a Princeton?

i just pick up today 2 Sunn 2000s heads and 1 sunn 2x15 cab and a 1979 Fender Bassman combo 4x10. (pics for proof)

so im all set with amps right now so I'll probably set it a side till i feel like building something. lol

[Tonyrhs13]

I wouldn't advice going overboard with the capacitance. Too much of it and the inrush will begin to blow fuses. Use caps that have equal or higher voltage rating than the caps you are replacing. For capacitance, get something that's in the ballpark of the old part.

If the old one was, say 500uF, don't use a 1000uF cap but maybe a 470uF, 520uF, or 560uF.

As for unobtanium germanium transistors. If they die replace with silicon and reconfigure the bias circuit. You probably won't notice much difference except for a huge improvement in reliability. R.G. Keen has written some good stuff about this issue concerning Thomas Organ solid-state Vox amplifiers. The good news: The information is for most parts interchangeable since you likely find a very similar design from these amps.

Schematics and layouts..? Heck, if you really need them just spend a few hours to sketch them out. With these kinds of amps it's still humanly possible without a microscope and without having to spend weeks into the process. If you choose to take that path then post the sketches here (or to the Internet in general) so that in the future there actually will be some information and technical documentary about these amps to help other guys like you.

yea i could get a sketch of it and upload it here. pictures of the wiring too would help others. i no how had it is to do something without a layout or schematic. but it will be a little bit (few weeks) got lots of projects right now.

thanks for all the input everyone!!

[Roly]

Why wreck it?  If you don't want it give it to somebody who can be bothered restoring it.  As for "parts" - it's 50 years old and there isn't anything in there that you can't buy better new, and a lot that is simply useless once it is pulled apart.

Why don't you have a go at tracing the circuit?  A bit like servicing an unknown stereo amp you seem to have two similar preamp boards to compare, and two similar output stages as well.  Tracing one of the preamps should give you most of the other one, and ditto for the two output stages (which are likely to be identical).

If you are going to be doing any work on this I'd apply some heatshrink to the mains socket inside to avoid accidentally "shaking hands with beef"; and the "ground" switch certainly needs cleaning up (if you haven't done so already).

It appears to have two power trannies, one for the low voltage to supply the preamps and driver, and the bigger one to power the output stages.

The small tranny down between the heatsinks suggests that this uses an old style transformer-coupled driver.  I'll attach a circuit of an amp that I think used a similar driver/output stage arrangement to give you the idea.

I'm guessing that the board mounted vertically in the middle will combine the two input channels and feed the driver; that transistor mounted on the back plate will be a class-A driver for the output stages; and the missing fuse holder may go some way to explaining why one channel isn't working.

It's going to need a few new electros, but frankly I think this would be a poor choice of metalwork for a valve/tube build.

[J M Fahey]

I think this would be a poor choice of metalwork for a valve/tube build.

Fully agree.
A tube chassis is thin (say 2 in deep) , has small parts inside, has a 4 to 6 in free space on the other side for tunes, transformewrs and large caps and on its surface has the sockets which jopin the inside and the outside world.
An SS Chassis is 4 to 6 in thick, has *everything* inside and nop free space outside because it does not need it.
ASbsolutely incomptible.
Better donate it to some poor bass player or whatever.
jm2c.

[joecool85]

...and the missing fuse holder may go some way to explaining why one channel isn't working.

I'm with Roly.  I'd try to fix it or give it away/sell it to someone who wants it.  No point in tearing it apart when it is almost fully functional and quite rare.