Repair or redesign?

I have an old behmoth of a solid state amp - an Audio Centron for pro audio use. One channel is out. It consists of a lot of discrete components on some PCBs driving a row of power transistors. I guess the cheapest thing is to just take the time to troubleshoot it, but before digging in to the dusty old monster I've considered the option of reusing the power components and replacing any dead power transistors, but then replacing the rest of the amp with some more modern circuits. Anybody know of sources or info on doing that? I know some electronic basics and have successfully modded my guitar tube amps, but have little experience with solid state circuits, so if there isn't already a beaten path I can follow I'm probably going to have some tough slogging.


2008-01-08 11:51 pm
It'll almost certainly be less trouble to fix it than to extensively rebuild it. I don't know this amp, but it's all discrete components, this generally means fixable, where if you had a lot if ICs in there, there might be problems.

The other big thing on your side, you've got a working channel. That means that you've got all the DC conditions. You can go from input to output following the signal path and cross checking from the working channel to the defunct one with a DMM. When you find different voltages from one channel to the other on an active component, you've pretty much located the problem area.

Be careful how you go, it only takes a slip with the DMM probe, if you short the wrong two points on the working channel, you'll lose that one as well.

IMO big old amps can be a great starting point for a new project, but only if you have a design you want to try and if that's your original intent. In every other case, repair will be a cheaper and better alternative. If you haven't built an amp from scratch before, it's best to start with something low powered- cheaper if you have a few mishaps!