Have a Boss CH3000D monoblock here that has an issue where the amp would thump the subwoofer in and out repeatedly when powered up and the amp powers up with remote but remains on when remote is removed and only turns off when RCAs are unplugged.
I found that the bass boost knob when turned would cause the subwoofer to pull in and out also. The knob was swapped out but the problem still exists. After changing the bass boost knob the amp would turn on and had clean output when tested in a vehicle but the thumping returned at high output level and then when the remote was turned off, the amp remained on until the RCA plugs were removed. There were a few strands of wire still soldered to the case of the input voltage selector switch as if there was a ground jumper that came off. I resoldered a wire to it and screwed it down to the regulators heatsink clamp but nothing changed.
I found that the bass boost knob when turned would cause the subwoofer to pull in and out also. The knob was swapped out but the problem still exists. After changing the bass boost knob the amp would turn on and had clean output when tested in a vehicle but the thumping returned at high output level and then when the remote was turned off, the amp remained on until the RCA plugs were removed. There were a few strands of wire still soldered to the case of the input voltage selector switch as if there was a ground jumper that came off. I resoldered a wire to it and screwed it down to the regulators heatsink clamp but nothing changed.
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Is there any DC voltage on the RCA shields?
Measure with the black on both the negative speaker terminal and the primary ground terminal.
Measure with the black on both the negative speaker terminal and the primary ground terminal.
The board is currently out of the heatsink. With the black probe on GND input there is -48v on the RCA shields, and 0.1v with the black probe on SPKR- terminal.
With black probe on GND input terminal, there is -48v on both speaker terminals, and the outputs are getting very hot when powered up.
What's the resistance from the RCA shields to the cathode of ZD5?
http://www.bcae1.com/temp/classDtype2wdriverboardindexa998.pdf
http://www.bcae1.com/temp/classDtype2wdriverboardindexa998.pdf
Getting a measurement of 2.8-3.3kohm from RCA shield to cathode of ZD5. The reading rises slowly upwards when probes are in contact with test points...
Same points, what's the DC voltage with the amp on?
Is the shield of your signal source grounded?
Compare the voltage on the terminals of the SG3525 with the amp on and again when the amp remote removed but RCAS plugged in.
Then again when you remove the RCAs and the amp shuts off.
No need to post all. Just note which ones change in each scenario.
Is the shield of your signal source grounded?
Compare the voltage on the terminals of the SG3525 with the amp on and again when the amp remote removed but RCAS plugged in.
Then again when you remove the RCAs and the amp shuts off.
No need to post all. Just note which ones change in each scenario.
Went to acquire the above requested information, and the amp went into protection. Posting the KA3525A voltages:
1) 2.6mv
2) 5V
3) 15mv
4) 213mv
5) 2.1V
6) 3.6V
7) 2V
8) 271mv
9) 5.5V
10) 24mv
11) 5.3mv
12) 2.5mv
13) 11.8V
14) 5.3mv
15) 11.8V
16) 5V
1) 2.6mv
2) 5V
3) 15mv
4) 213mv
5) 2.1V
6) 3.6V
7) 2V
8) 271mv
9) 5.5V
10) 24mv
11) 5.3mv
12) 2.5mv
13) 11.8V
14) 5.3mv
15) 11.8V
16) 5V
After it went into protect, did you confirm that all voltages were essentially the same as they were before it went into protect?
Which terminal, when you probed it, caused it to go into protect?
Which terminal, when you probed it, caused it to go into protect?
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What happened is that I powered the amp up without RCAs connected and then turned off remote power. The green led remained on and after a few seconds it started to flicker a bit and there was an 'arcing' sound coming from the area of the traces running between the rail caps and the transformer, under the 'aged fixative'. I could see visible flashes, and then it stopped and the amp shut off. Afterwards, it would only power up into protection. I removed the fixative from the area expecting to find a burnt/separated trace underneath, but it wasn't.
The only other thing is that pressing on the circuit board in the area of the bass boost knob and that general end of the amplifier would cause the protection light to turn off when it was remaining on after remote power was removed.
The only other thing is that pressing on the circuit board in the area of the bass boost knob and that general end of the amplifier would cause the protection light to turn off when it was remaining on after remote power was removed.
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That fixative becomes both conductive and corrosive. You need to remove 100% of it (everywhere) before doing any more troubleshooting.
Removed all the fixative from the circuit board and cleaned it off of all the traces, resistor and diode legs that it was on. The amp is currently still powering up into protection.
KA3525 voltages:
1) 3.7mv
2) 5V
3) 16mv
4) 211mv
5) 2.1V
6) 3.6V
7) 2V
8) 271mv
9) 5.5V
10) 24mv
11) 5.9mv
12) 3.1mv
13) 11.8V
14) 5.3mv
15) 11.8V
16) 5V
KA3525 voltages:
1) 3.7mv
2) 5V
3) 16mv
4) 211mv
5) 2.1V
6) 3.6V
7) 2V
8) 271mv
9) 5.5V
10) 24mv
11) 5.9mv
12) 3.1mv
13) 11.8V
14) 5.3mv
15) 11.8V
16) 5V
If you want to try to force the 3525 on (be careful), you can sometimes do it by jumping the softstart pin to the 5v output of the IC.
If this doesn't work, note whether the 5v is pulled down or the SS is pulled up.
If this doesn't work, note whether the 5v is pulled down or the SS is pulled up.
The moment the wire from pin16 touches the pin8 terminal, there is a loud buzz from the amp so I didn't hold it on any longer. The 5v is pulled down on that jumper wire and the fan speed drops as well but the mains limiter does not light up though.