Power Acoustic GT1-4500D

[Andregopee]

I am working on a Power Acoustic GT1-4500D Mono block and the amp powers on in protect mode and then shuts down. I have check the power supply and I and getting my rail voltages at the Rectifying diodes D423, 424, D323 and 324, Can anyone supply me with a service manual? or point me in the right direction? Thanks.

 

[Perry Babin]

If you can't get a diagram from the manufacturer, post a photo of the board.

 

[Andregopee]

Thanks Perry, I'll post some pictures of the board.

 

[Andregopee]

Power Acoustic GT1-5400D Pictures

Perry, these are the pictures of the board. Let me know if you need anything else.

 

[Perry Babin]

I don't have a diagram for it but the soundstream ta1.2000d is very similar. If PA tech support won't help, try soundstream.

The 4 MPSA42s along the bottom of the driver board fail. Do the solder connections look like they've been very hot?

 

[Andregopee]

Thanks Perry. I will solder out those Transistor and give them a check. I had change the driver IC but that didn't help.

 

[Stetsom23]

That driver audio board fails
Try desolder the audio board and try again. If tbe amp power up with the voltages correct. The audioboard is bad. I replace ALL transistors and the ic and amps go out working

 

[Perry Babin]

That's why I asked about the solder connections. The 6000 version has problems with severe overheating. I've never seen the 4500. In the 6000, I add a 40mm fan that blows across the board.

 

[Andregopee]

I desoldered the audio board and change all the transistors... I am getting my 68 Volts on the output mosfets but not the drive signal. I put the audio board on headers so as to not damage the connection by taking it in and out. I had found two small resistor type capacitor on the board that is bad. one I replace and the other I can't figure out. I have inserted a picture of the capacitor. Can anyone tell me the value? The colors are Brown, Black, Black. I thinks it is a 10 PF but not sure.

 

[Perry Babin]

10pf is likely correct.

Is it shorted?

Did you try driving a signal into the amp? Sometimes, self oscillating amps won't oscillate until they get a signal.

 

[Andregopee]

Yes it is shorted and yes I input a audio signal and it still does not work.

 

[Andregopee]

Okay guys, I finally got the amp working... and yes Perry you were correct in saying that the amp might be self oscillating. The 10 PF cap on the driver board was shorted and I change it and it came back to life. Thanks guys for all the help.