problem with first ever diy amp

laki101

Member
2009-12-24 12:47 pm
So after a year finally today made my first ever diy amp using this PA100 DIY 2x LM3886 in parallel gainclone audio amplifier
1. conecetd just the power and turned it on, just to chack for some sparks :D and shorts
2. conected a speaker, now here the problems start it made a constant interval crack sound like it had voltage going to the speaker
3. conected a source an min volume the cracking continued, now as I volumed it up it started to do some good, it worked :) but the cracking was still present but weary quiet and it hade a quiet buzing noise

then i looked and the link and there is a part about seperating the signal and the power ground so I did that compleatly seperating it, now it ofcorse did not work beacuse the next sentence there is that it is conected but just at one small part
so i do that

power up, 3 weary loud clicks, thana sileance and than one LM3886 begins to extreamly overheat

power off

after 2 minutes just to chek if its really toasted start it up now boat lm3886s began to overheat and I was getting 35V at the audio out so a big problem

now i gues the lms are toast but the other component shoul be ok right?

and what coul be the problem because I dont want to toast any more chips :D
 

Mooly

Administrator
Paid Member
2007-09-15 8:14 am
If you have built it on proper PCB's as in the link then power up with just one channel fitted (1 pcb) and with just 1 LM3886 fitted. NO speaker connected. Also use a 60watt bulb in series with the primary of the mains tranny for all testing.

That's the first step...