Rockford 1501bd

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Hi all, I have a Rockford 1501bd pulling excessive current, it also produces a high pitched squeal from near the power terminals.

I only powered it up momentarily to avoid further damage.

Not sure where to start with this one, there's no physical damage on visual inspection.

None of the outputs are shorted either?

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Thanks for the suggestion Perry,

I tried the jumper across C51 and it made no difference.
When I re tested I noticed upon connecting the remote wire the amp briefly draws excessive current and the red led lights up for half a second then the current draw drops off to zero and the led turns off.

I also noticed 3 red wires from the lower torroid had either worked loose from the board or had been lifted by someone.

I re-soldered them and it made no difference.

So when remote power is applied the amp appears to charge up the caps, the red led momentarily lights up and then nothing. Could it be going into protection mode?


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Either something is pulling pin 18 down or the 3526 is defective. If you have the jumper on C51, remove it and recheck pin 18. It should be 5v ±1%.

If you have the 3526 and you replace it, R34 may need to be replaced with a resistor. I've been using a 1k resistor. Some replacement ICs will fail to oscillate with the 0 ohm R34 in the circuit.
 
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Hi Perry,

so I replaced R34 with a 1k resistor and no change.

I measured the pins on the 3526 and the results are as follows

1, 2.24v
2, 0.08v
3, 079.6v
4, 007.0v
5, 060.7v
6, 000.9v
7, 000.8v
8, 005.2v
9, 009.6v

10, 0.56v
11, 002.0
12, 1.30v
13, 000.3v
14, 13.8v
15, 000.7v
16, 000.4v
17, 13.8v
18, 2.19v
 
For future reference, when R34 is an issue, the IS will produce no pulses.

The problem was that the IC was defective OR something was pulling pin 18 down.

Are any of the ICs, U13, U16 or the IC labeled Q31 getting warm?

Tantalum capacitors like C95 and C72 have a high failure rate and could be leaking internally. You may want to pill those to see if the voltage on pin 18 goes back up to 5v.
 
Success .... all the aforementioned ICs were running cool, I pulled C95 and no change.

Next I pulled C72 and the amp powered on, its currently drawing a steady 2 amp at idle.

I didn't know Tantalum capacitors could leak, that's a good lesson learned for the future.

Thank you Perry for sharing your knowledge, I really appreciate your help as always.
 
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This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.