Audiopipe AP 3000 1D

[Perry Babin]

The sla1500 is 1/2 of this amp.
http://www.bcae1.com/temp/SLA1500.pdf

On only 1 lead of the output filter inductor? That's not likely. Re-check.

 

[caraudioguy2100]

Ok I get 73 volts on both sides of the inductor.

The drivers MMBT4401 and 4403 are brand new also the outputs are brand new
Bought them from mouser electronics .

I cannot seem to find where the problem is with the 1 board causing 73 volts across the speaker terminals .

Any ideas or can point me in the right direction ?

 

[Perry Babin]

Pull the rectifiers again and re-check the drive signals at the gates of all of the output FETs on that board.

 

[caraudioguy2100]

On outputs Q5,Q6,Q7,Q8 I get no drive signal.

 

[Perry Babin]

Do you have a square wave driving the input to the optocoupler on that side of the board?

Does that optocoupler have output and supply voltage?

 

[caraudioguy2100]

I do not get a square wave driving the input to the optocoupler

Here’s what I get in the optocoupler

6N137

Pin 1:0.00
Pin 2:0.76
Pin 3:0.00
Pin 4:0.00
Pin 5:-2.45
Pin 6:2.14
Pin 7:-0.63
Pin 8:2.37

 

[caraudioguy2100]

Ok I replaced the optocoupler and now I have drive signal on the outputs .

 

[caraudioguy2100]

This is the drive signals for both high and low side

Scope settings are 2us 5 volts/div

 

[Perry Babin]

Is this a test?

The waveforms look OK if you forgot to center the trace on the reference.

The frequency looks normal for 5us.

 

[caraudioguy2100]

Put the amp back together to test am the optocoupler blew again.

So the 70 volts is present again across the speaker terminals

Any idea what might cause this

 

[Perry Babin]

Is the optocoupler the only thing that failed?

 

[caraudioguy2100]

Yes

 

[Perry Babin]

Which side is failing (input or output)?

 

[caraudioguy2100]

Output side

 

[Perry Babin]

What's the resistance between pins 6 and 8?

 

[caraudioguy2100]

0.678k ohms

Must have confused the sides I believe the input side is blown

 

[Perry Babin]

How is it failing? Is the internal LED opening?

 

[caraudioguy2100]

I had no drive signal replaced the optocoupler and had good drive signal .

It blew again and have no drive signal again and 70 volts across the speaker terminals

 

[Perry Babin]

What was the drive signal you were seeing? Was it the audio frequency that you drove into the amp or was it a high frequency (80kHz) signal?

 

[caraudioguy2100]

The high frequency 80k hertz