Power Acoustik BAMF5500, no output

[FireII]

Howdy,
I got a Power Acoustik BAMF 5500 that produces no audio output. I've got 115v +/- on the rectifiers, no DC on output terminals, actually I've got 0.0000v on terminals(seems strange because I've never had that exact of a number before, they are not shorted though), I can't trace down the audio signal because as soon as they go through the first 15,000ohm resistor the signal is no longer usable.Output voltages are as follows -

IRFP264N

NEG
Gate -115
Drain 0
Source -116

POS
Gate 0
Drain +115
Source 0

Edit : Customer said he was "beatin' on it pretty hard when it cut out", I hear the relays click during power on and power off, but I'm not sure how the power acoutiks go about clamping the signal.

 

[Perry Babin]

Do you have signal on the small output filter inductor?

If so, the relays may have failed. When they fail, they generally melt.

 

[FireII]

I do not, before when I wrote I had zero output signal, after doing some probing I've managed to get a VERY small output on audio components, not sure how it came about but it's only ~10mV that does correspond with the input sine wave.

Kinda scratchin my head on this one.....

The relays appear to be fine, visually, but I have not checked for sure. How does this amp go about clamping the signal?

 

[Perry Babin]

Is there any significant DC on the output pins of the op-amps near the RCA jacks?

 

[FireII]

Is there any significant DC on the output pins of the op-amps near the RCA jacks?

I have half a volt on one, the rest are ~3mV

 

[Perry Babin]

1/2v seems a bit high.

Do you have audio reaching the class D driver board?

If not, have you followed it through the op-amps to see where it stops?

 

[FireII]

1/2v seems a bit high.

Do you have audio reaching the class D driver board?

If not, have you followed it through the op-amps to see where it stops?

Yes, I do have audio in the driver board. As to where it starts and ends, I'm not sure. My "specialty" has been in older A/B amps, with only about 15% of my business being class D, you'll have to excuse my ignorance.

 

[FireII]

I've found the output drivers on the driver board, the signal is VERY weak, I can only see the negative half with my scope because the positive side has such high voltage on them.

 

[FireII]

Do you happen to know where the relay outputs are on the top side of the board? I noticed that the clicking only happends when B+ is applied or taken away from B+ and B-, not remote.

 

[Perry Babin]

The relays connect the small inductor to the positive speaker terminals. Do you have the board out of the sink?

 

[FireII]

The relays connect the small inductor to the positive speaker terminals. Do you have the board out of the sink?

I do now I'm trying to figure out the pin configuration, I got frustrated trying to find a schematic on them.

 

[FireII]

Just to make sure, this is the board your referring to, correct?

 

[Perry Babin]

Were you looking for the relay pin configuration?

That's the board.

Do any of the outputs have the legs broken at the point where they make contact with the solder?

 

[FireII]

I reflowed the solder just to make sure, still the same senario.

I did noticed that the coils of the relays are directly connected to B+ and B-.... this doesn't seem right to me, the relays are on with only having B+ and B- connected....

EDIT: Also, if this were a typicall relay, where would 87a(pin 4) connect to? Does this pin have anything to do with the driver board "running"? I still don't think that the driver board is working correctly because of the very weak drive signal.

 

[Perry Babin]

The orange line is the connection between the inductor and the relay. The yellow line is the path from the relay to the terminals.

The photo of the relay shows typical damage when the relays fail.

The high current terminals of the relay shouldn't have any connection to the B+ or ground terminals.

Can you post a photo of the drive signal on pin 1 of the IR2110S driver IC?

 

[FireII]

The orange line is the connection between the inductor and the relay. The yellow line is the path from the relay to the terminals.

The photo of the relay shows typical damage when the relays fail.

The high current terminals of the relay shouldn't have any connection to the B+ or ground terminals.

Can you post a photo of the drive signal on pin 1 of the IR2110S driver IC?

From the schematics of your diagram, pins 2 and 6 go directly to the power terminals, on a bosch relay they would be equivalent to pins 86 and 85. When those terminals get 12v, pin 5 switches to pin 3 connecting the inductor to the positive output terminals. Still stumped as to why the relays turn on only with B+ connected and not remote, somthing shorted?

Pin1 of the IR2110S has 115v DC on it.

 

[Perry Babin]

+115 or -115?

Any drive signal?

Are the relays connecting the inductor to the positive speaker terminals properly (~0 ohms between inductor and positive speaker terminals)?

Is Q71 shorted? Edit: Not Q71. The transistor against the relay.

 

[FireII]

+115 or -115?

Any drive signal?

Are the relays connecting the inductor to the positive speaker terminals properly (~0 ohms between inductor and positive speaker terminals)?

Is Q71 shorted? Edit: Not Q71. The transistor against the relay.

Yes, when the relays turn on they are connecting the inductor to the positive speaker terminals, Yes, that transistor is shorted and it was -115v on pin 1.

 

[Perry Babin]

Was there any drive signal on pin 1?

You may have to set the scope to AC coupling. Set the vertical amp to 10v'div and the time base to about 5uS.

 

[FireII]

Was there any drive signal on pin 1?

You may have to set the scope to AC coupling. Set the vertical amp to 10v'div and the time base to about 5uS.

I'll be sure to try that, I know before I wasn't able to lock onto any drive signal at all. I'll get back with you tomorrow evening. I gotta get to bed so that I can teach students about ohms/watts law tomorrow..... yay .

Thanks for your help, Perry.