Powerbass 6000w

[Aqeeb127]

Hi i need help with this amp everything is working but no switching on the output section

 

[Aqeeb127]

These are the images of the amp

 

[DanFS722]

test the switching transistors out of circuit.

 

[Perry Babin]

With the black probe on the negative rail. what's the DC voltage on pin 2 of the 21844?

If you drive a signal into the amp, do you see that signal on the output terminals of the TL072 and the Lm211 on the driver board?

 

[Aqeeb127]

I changed the tl072 other guy told me i should change that and there is output on the 072 and there is output on the lm211

 

[Aqeeb127]

Pin 2 on 21844 is reading approximately 300mV

 

[Perry Babin]

It should be near 5v. Check the muting transistor.

 

[Aqeeb127]

Ive already checked this transistor but it seems the problem is lying on the main board as i had audio out then took remote off and reapplied the remote then it didnt have audio again

 

[Perry Babin]

Does the power supply shut down when you have no audio?

 

[Aqeeb127]

No it does not shut down ive resoldered the whole board also i cannot find why its doing this

 

[Aqeeb127]

I resoldered the inductor last night and had audio then i took the remote off and applied it again then no audio output. Then replaced the inductor with the exact same inductor from a donor board then it worked again and now its again no output audio

 

[Aqeeb127]

All voltages are present going into the driver card and i have replace the card also with a known working card still the same issue

 

[Perry Babin]

Does the protect LED light up?

 

[Aqeeb127]

No it does not it powers up fully

 

[Perry Babin]

Did you check the muting transistor for leakage?

As a side note, it's bad practice to resolder large areas of the board. Bad connections typically have a layer of oxide that may not fully float to the surface. This will leave a connection that's marginal at best and likely to fail again. It's better to troubleshoot to find the fault and if it's a bad connection, then you properly repair that one connection.

 

[Aqeeb127]

Ok thanks for the tip and i took out the mute transistor and audio is back and no leakage.

 

[Perry Babin]

Some amps seem to be sensitive to not having a mute delay (they will blow the output FETs).

Repeatedly power up the amp (muting transistor in the circuit) and measure the DC voltage on pin 2. Does the voltage remain relatively constant when it has audio and when there is no audio? Or does the voltage vary widely?

 

[Aqeeb127]

On a working amp similar model it varies widely but i will have to check this amp

 

[Aqeeb127]

It stays constant with it in and no audio out

 

[Aqeeb127]

53v on pin 2 referenced to ground