electronics, repairs, service manuals and datasheets discussion community for the repairs professionals and technicians
FAQSearchMembersGroupsRegisterProfilePM'sLogin/Out
New here, amp repair?

 
Post new topic   Reply to topic    Electronic equipment repair and service manual search discussion Forum Index -> Equipment Repairs
View previous topic :: View next topic  
Author Message
madmoody



Joined: 19 Jun 2007
Posts: 1

PostPosted: Wed Jun 20, 2007 5:06 am    Post subject: New here, amp repair? Reply with quote

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?
Back to top
View user's profile Send private message
vtech



Joined: 08 May 2006
Posts: 1264
Location: USA

PostPosted: Thu Jun 21, 2007 10:46 pm    Post subject: Reply with quote

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.
Back to top
View user's profile Send private message
Display posts from previous:   
Post new topic   Reply to topic    Electronic equipment repair and service manual search discussion Forum Index -> Equipment Repairs All times are GMT
Page 1 of 1

 
Jump to:  
You can post new topics in this forum
You can reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum


Електроника София - Service Manuals Free Download - Prikachi - Service Diagrams

Free TV Schematics Download - HARDW.net - Pinout Master - Jabse Search - Jabse.InK  - Pulsator

Connector Pinout Forum - Новини - SnimkiOt.com - безплатен DNS - Whois разузнаване - Poblizo.com : пътешествия