Power Acoustic OV1-5500D

S Merlington · 2013-11-03 11:13 am

This amp is the same design that many amp manufactors use..

This is the board where the Audio driverboard sits in front of a fan..

Amp powers up idels perfectly all rail and regualted voltages are correct..

Amp has very very low output u have to put your ear to the test spaeker in order to hear it..

Any ideas what might cause this??

Perry Babin · 2013-11-03 4:06 pm

master/slave switch not set to master?

If that's not it, do you have rail-rail oscillation on the output transistors?

S Merlington · 2013-11-04 6:04 am

Switch was set to master..

I have rail to rail oscillation on the outputs.. Nice sqaure wave

S Merlington · 2013-11-04 7:10 am

Ok i noticed the Vias is damaged on the pads for the audio driverboard i will fix the connections from the top of the board to the bottom of the board ..

I will post back once i fix this

S Merlington · 2013-11-04 3:42 pm

Ok fixed that now i have another issue..

A screwdrive rolled across my bench and hit 1 of the outputs when that amp was powerd up..

had a big spark but it didnt blow the output ..

I removed the output and powerd the amp up again now it stuck in protection mode..

If i remove all the low side outputs amp will power up and idle fine..

I tryed to put 1 brand new output on the low side but as soon as i do the amp protects..

Would the driverboard be the most likely cause of this??

S Merlington · 2013-11-13 5:41 am

Any ideas what might cause this amp to protect when the audio driverboard is in the amp???

As soon as i removed it the amp powers up and idles fine

Perry Babin · 2013-11-13 5:46 am

Do you see a pulse of DC on the positive speaker terminal when the amp is powered up with the outputs and driver board in the circuit?

If so, is the pulse positive or negative?

S Merlington · 2013-11-13 5:55 am

Yes I get a pulse of -18.33 volts

Perry Babin · 2013-11-13 6:35 am

Q124 and Q125 would be the most likely suspects. Those drive the low-side FETs on. Q126 and Q127 may be damaged as well. Check for leakage as well as shorts and opens.

S Merlington · 2013-11-13 7:50 am

Ok the problem is with the + 15 volts ..

The regulator is working correctly..

If i power the amp up it will flash in and out of protection..

If i remove the 7815 regulator the amp will power up normally

Perry Babin · 2013-11-13 10:06 am

Is this with all other components in the board?

S Merlington · 2013-11-13 4:56 pm

Perry Babin · 2013-11-13 4:58 pm

Did you (carefully) check the transistors that I listed?

S Merlington · 2013-11-13 5:22 pm

I replaced them also replaced all the A56's ,A92's and 42's tested the others in the board all tested fine

Perry Babin · 2013-11-13 5:29 pm

Is it still producing the same negative pulse?

The regulator affects many different things.

Is there any discoloration between the pads for Q124/125 or anything else in that area of the driver board?

S Merlington · 2013-11-13 6:01 pm

No discoloration in that area..

Its still producing the negative pulse

namesmeanlittle · 2013-11-15 5:45 am

i dont fix amps but it sounds like a driver or bias problem

S Merlington · 2013-11-15 2:44 pm

Perry,

Should i look at the driverboard some more??

Cant figure out why this amp is stuck in protection mode with the audio driverboard in the amp but as soon as i remove it the amp powers up perfectly..

Perry Babin · 2013-11-15 3:12 pm

Pull Q124 and Q125 and confirm that there are no solder bridges on either side of the driver board.

Does that eliminate the negative DC pulses?

S Merlington · 2013-11-15 3:17 pm

with the driverboard removed i get -0.14 volts on the positive speaker terminal not sure if this is a problem or not

Power Acoustic OV1-5500D

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