Audiopipe ACPL-30001D

[RJohns777]

Hi. Working on an Audiopipe ACPL-30001D. The outputs on one amp board are running hot and will eventually short. The other board runs fine. I removed the rectifiers in both board to compare drive signals. Both look very much the same. The only difference I see is in frequency. The board running correctly is 144.4 kHz. The board over heating is 120.5 kHz. Gate voltage DC and peak to peak are very close to the same. Q11,12,13&14 driver transistors check good. Any ideas?

 

[Perry Babin]

It's difficult to see what the drive signal looks like when there is modulation.

 

[Hexhclass]

I had one in where the solder melt and cause a bridge across the speaker terminals.

 

[RJohns777]

Here's pics with no input signal. 144kHz is the channel not shorting outputs. Taken at the gate lead.

 

[RJohns777]

ian33, When this one came in it was shorted with melted solder across turn-no and ground. That was an easy fix. Now I'm dealing with one of the 1500s shorting outputs. The other 1500 runs fine. Thanks.

 

[Perry Babin]

This is only one drive circuit (high or low). What does the other look like?

 

[RJohns777]

It's the high drive circuit. The low looks identical. I can take a pic if you want.

 

[Perry Babin]

I don't see anything wrong with the drive.

Do the outputs heat up before failing?

Does the amp draw more current when the failing channel is at idle (compared to the other channel)?

Does twisting the inductor make a difference in the idle current?

 

[RJohns777]

So the frequency between the two amps doesn't matter?


Yes the outputs heat up before failing.


I'll have to check the current and let you know. I have to put the rectifiers back in the amp. Tried that before I pulled the rectifiers.



Twisting the inductor makes no difference.

 

[Perry Babin]

Some of this type amp are clocked and some are self oscillating. The self-oscillating ones vary greatly in frequency as the output power changes. 120k vs 144k should be insignificant. If it was 20k or 250k, maybe.

Check to see if the inductor heats evenly all around. If it heats significantly in one area, that could indicate that it's shorted.

 

[RJohns777]

Follow up and hopefully ending to this thread. Drives to the outputs looked good. Put the amp back together. New set of outputs. Idling at 100 watts. Pulling 15 amps. So far it's playing fine. Not over heating on the outputs. Inductor seems to be heating evenly. Twisting the inductor makes no difference. I will let idle for awhile and crank it up. We will see. Thanks for the help.