ROCKFORD Fosgate t10001bd 2004

[rhempz01]

Amplifier is stuck in protection. All outputs, and the power supply fets test good. The power supply has drive. No oscillation.
No negative regulated on the op amps.

 

[Perry Babin]

Does the negative regulator have output?

 

[rhempz01]

All positive, even if I switch out the lm337t, the small 10uf caps in the curcuit in front of the regulators are all corroded. Despite changing them the result is the same.

 

[Perry Babin]

Are you saying that the input to the negative regulator is positive?

Good quality photo?

 

[miniman82]

All positive, even if I switch out the lm337t, the small 10uf caps in the curcuit in front of the regulators are all corroded. Despite changing them the result is the same.

If they leaked electrolyte, you'll have to scrub the board really well with alcohol or some other solvent to get the crud off the board. Replace the caps, try again.

 

[rhempz01]

U8 DC left to right.

1.) .755
2.) . 341
3.) .770

 

[rhempz01]

Photos

 

[rhempz01]

2

 

[Perry Babin]

Check CR1 and CR2. If they're OK, confirm that there is input to those rectifiers and that there is a good connection between their anode and the negative regulator.

 

[rhempz01]

Cr1 & cr2 have -18.50vdc.

 

[seankane]

I had one do this and it was a shorted output. It tested normal with your quick gate to source test with an ohm meter, but when I switched the probes in all configurations I found one that was shorted.


You have -18v at CR1 and CR2. Did you confirm they read ok as far as testing them with your meter?


Did you confirm what Perry asked for the good connection between their anode and the negative regulator?

 

[rhempz01]

Hmn I'll check that Sean,

I not sure if a good connection or not. I do not have that negative voltage at the regulator.
I have 3.385mohms from the diode to the regulator center leg?
Both are the same
I CHANGED THEM FOR GOOD MEASURE AS WELL.
I can check the outputs more throughly for a short.

 

[rhempz01]

What size caps are supposed to smd caps around the outputs c237, c235, c236 ect. 68uf? 100v

 

[rhempz01]

Here a lot of these hole through are broke loose at the pads.

 

[seankane]

They are .0068uf 50V.

 

[rhempz01]

I'm confused as to where I should have my lm337t connected to the - 18.50, there is no broken or burnt connections.
Despite fixing the capacitance of the outputs the amplifier remains with that positive voltage on the lm337t
Should jumper a connection somewhere?

 

[Perry Babin]

Looking at the 337 datasheet, the input is pin 2.

The voltage is positive because voltage is leaking from the components that have positive voltage but no negative voltage.