New here, amp repair?

[madmoody]

Hi people,

I'm not exactly well versed in electronics. I know how to be safe, I can solder and replace components but I can't say that I know what is going on.

I got given a non-working 100watt pa amplifier (practice 6 input thing probably from the early 80's) from a friend. I hooked up a cheap old speaker for a second and got DC hum (I know that sound and it hasn't been my friend before). I switched the amp off before the speaker got fried.

I opened up the amp and it has a couple of big leaky caps in the power section but nothing else seems 'obviously' wrong with it from a visual inspection. The preamp section is way to complicated for me to even start looking at and I don't think that would be the cause of this sort of problem anyway.

I can get the caps and transistors replaced for about $15. I'm trying to figure out if that would be likely to fix the problem. Spending much more than that wouldn't be worthwhile for the amplifier.

Opinions? Questions?

[vtech]

Several possibilities DEPENDING on what type of an amp & design;

It is quite possible that the "hum" that was heard is only due to leaky/dried up electrolytic caps , BUT if the output transistors are infact bad and there is NO speaker protection, (some inexpensive amps did not have it) the "hum' could have already damaged/fried your speaker by putting rail voltage across the speaker----(can not be quick enough to protect a speaker by shutting off). Need to do furthrt testing before hooking speaker up.

Btw.... $15.00 sounds too cheap for caps AND transistors repalcement.