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RockfordFIx 27th February 2013 12:09 PM

Rockford Fosgate BD1000@1
Hey guys,

I am working on a bd1000 and have 36v on the speaker output. I replace the powersupply fets and the output fets. I also had to replace one of the ic drivers
MIC4420CT cause it was shorted. Amp powers up fine, only thing i noticed out of the ordinary was using diode check on my meter from (+) on source and (-) on drain it read correct around .498 vdc. When i reversed the leads it would read a short 0.000vdc. I think this causing my problem not sure if the fets are leaking or if there is a bad component somewhere else.

Perry Babin 27th February 2013 01:26 PM

Some meters won't read correctly if there is voltage present in the circuit. Charged capacitors can provide enough voltage to cause this problem. I'm guessing that this isn't a Fluke meter.

Post the DC voltage on all pins of U17.

RockfordFIx 28th February 2013 12:24 PM

Damn your. Good ..and yes its not a fluke..

1= nc
2= 0.021
3= 0.002
4= -9.70
5= nc
6= 9.88

Perry Babin 28th February 2013 01:10 PM

Something doesn't seem right. You have positive output on pin 6 but no supply voltage on pin 7. Re-check the voltage.

Is the voltage on the positive speaker terminal positive or negative 36v?

RockfordFIx 28th February 2013 02:14 PM


My mistake reading the pin-out of the chip wrong..

6= 0.006
7= 9.88

the output on the speaker terminal is +5.025vdc this morning. At one point i noticed the protect light was on and the output on the speaker terminals was 0.00vdc and the output pin 6 on u17 was 8.58 vdc. Pin 2 was 1.021vdc. I removed power and it went back to normal mode and was reading 5vdc on speaker terminal.

Perry Babin 28th February 2013 04:19 PM

Post the DC voltage on all pins of U11.

RockfordFIx 1st March 2013 11:42 AM

1= -0.005
2= 0.004
3= 0.005
4= -9.65
5= 0.005
6= 0.005
7= 0.055
8= 9.89

Perry Babin 1st March 2013 09:06 PM

Those look OK.

Can you power it up and down a few more times, posting the voltage on pins 2 and 6 of U17 as well as the DC on the output?

The voltage on U17 is inconclusive. It appears that it could possibly be defective but with only about 20mv difference between the two inputs, it's hard to tell.

RockfordFIx 2nd March 2013 02:48 PM

Perry the pin voltages were about the same. Although, i did notice the voltage on speaker terminal would start to increase to 4.35v and when power is removed it immediately drops to .678 volts. The voltage is not very stable and tends to bounce from 4v to 4.38v.

Perry Babin 2nd March 2013 02:51 PM

Just to confirm... The protect LED is on for a few seconds after remote voltage is applied, then goes off. Is that correct?

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