Rockville DB comp5

[caraudioguy2100]

Regulator problem fixed .

Now I have another problem .

If I leave the audio driverboard out of the amp it will power up fine

If I install the audio driverboard the amp protects .

I checked the driver ic’s and they check fine is there anything else on these boards that will make the amp protect ?

 

[Perry Babin]

It could be that the driver board is causing DC to be driven to the output of the amp.

It could also be that there is a problem with the over-current protection on the driver board.

Are the outputs in the circuit?

 

[caraudioguy2100]

The outputs were in circuit .

I powered the amp up and it went into protection

I shut it down and powered it back up amp would sit and idle for 30 secs then protect did this a couple times then it blew the outputs .

 

[Perry Babin]

Is rail voltage building fully before the output stage starts to oscillate?

Are there any damaged vias on the driver board?

 

[caraudioguy2100]

No damaged vias on the driverboard .

I will check to see if the rail voltage builds fully before the outputs stage starts to oscillate .

 

[caraudioguy2100]

I replaced all of the ic’s on the audio driver board .

Also replaced all of the smd transistors on the driverboard with the exception of the ones labeled max .

Amp will power up and idle perfectly without the audio driver board installed


If I put the audio driverboard in the amp it will
Power up for about 20 secs then protect and blow an output.

The original problem was that a speaker wire got grounded out to the case of the amp .

Any ideas on what to check ?

 

[caraudioguy2100]

Some more messing with this amp .

If I power the amp up after sitting awhile it will protect if I cycle the remote wire 5 or 6 times the amp will power up and play clean audio .


Amp will play about 3 mins clean audio then it will protect again if I cycle the remote wire again 5 or 6 times it will play clean audio again .

Any ideas what might cause this ?

 

[caraudioguy2100]

Still can’t figure this out been checking everything and everything I test checks good .

Any ideas on what might cause this issue ?

 

[Perry Babin]

Is there any DC building on the speaker terminal when it shuts down?

Does it shut down idling?

 

[caraudioguy2100]

It shuts down when idling .


When the amp starts to protect I get a spike of 4 volts across the speaker terminals

 

[Perry Babin]

What do you mean by 'starts to protect'? Can you see something change that tells you that it's about to shut down?

What sort of spike? A short pulse or a 4v DC output that lasts until the amp shuts down?

 

[caraudioguy2100]

Sorry I worded that wrong .

The voltage measured directly across the speaker terminals is 0.1 volts

As soon as the amp protects and the really clicks I bet a 4 volt spike across the output terminals

I get a voltage spike across speaker terminals when the amp protects and install drops back down to 0 volts

 

[caraudioguy2100]

Should I check anything else ?

 

[Perry Babin]

So, the voltage across the speaker terminals is 0.1v up until the instant that the relay disengages. Is that correct?

Does a speaker connected to the speaker terminals pop when the amp goes into protect?

 

[caraudioguy2100]

Yes 0.1 volts up until the amp protects .

The speaker pops when the amp protects .

 

[Perry Babin]

Does heating/cooling any of the components change the way it goes into protect?

What about pushing on various parts of the board?

Left idling, do you see a change in the pulse width in the r-r oscillation as it goes into protect?

 

[caraudioguy2100]

It might be easier to track down now .

Whatever it is was Intermittently causing problems now the amp will not come out of protection mode and the clip light is on also

 

[caraudioguy2100]

I think the problem still is in the regulator circuit .

I have 15 volts at the regulators but only have -12 volts at opamp and + 2 volts at opamp

 

[Perry Babin]

What's the resistance from the +15v regulator output to the positive supply terminal of the op-amps?

Measure the same for the negative circuit.

 

[caraudioguy2100]

0.2 ohms on both .

The problem I’m having now is the regulated voltage is not right .


From the output terminal of the positive regulator to the positive terminal of opamp I get 0.2 ohms

Negative regulator output to negative terminal of opamp I get 0.2 ohms

If I use the ground leg of the regulators I get +- 15 volts on the regulators .

On the opamps them selfs on pin 4 I get -27.01
On pin 8 I get 3.08