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madmoody
Joined: 19 Jun 2007 Posts: 1
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Posted: Wed Jun 20, 2007 5:06 am Post subject: New here, amp repair? |
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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? |
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vtech
Joined: 08 May 2006 Posts: 1264 Location: USA
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Posted: Thu Jun 21, 2007 10:46 pm Post subject: |
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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. |
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