Alpine 3555 4ch loud turn ON/OFF pop

[nonprof]

Hello!

I almost ended up thinking what's the problem of this amp. The speaker pulls and loud turn ON/OFF pop during on and off this amplifier. Anyone has an idea how to repair this amp?

Music is clear but not this problem.

thank you so much!

 

[Perry Babin]

How long does the speaker pull in?

Do all 4 channels do this?

Do you have ±15v on the op-amp power supply pins?

 

[nonprof]

How long does the speaker pull in? it happens around 1 sec after you apply the voltage to remote IN and the pull in takes approx 1 sec.

Do all 4 channels do this? All channels do this.

Do you have ±15v on the op-amp power supply pins? Yes I have +-12V(not sure or +-15V), the original problem of this amp is blown 4 capacitors at regulated supply(+-15V).

Thanks for helping...

 

[Perry Babin]

Does the DC voltage on all bridging speaker terminals go positive or all negative or a mix (specify)?

Black probe on one non-bridging terminal. Use the same for all bridging terminals.

 

[nonprof]

Does the DC voltage on all bridging speaker terminals go positive or all negative or a mix (specify)?

Black probe on one non-bridging terminal. Use the same for all bridging terminals.

thanks....ill take measurements get back to you tomorrow.

 

[nonprof]

hi Perry, All output channels swings from positive to negative at around 5volts. channel 1 & 2 has a louder pop. speakers push and pull in a millisecond. i shorted the input signal to sgnd in a mute transistor per channel but pop remains.

 

[nonprof]

hello...


pls give advice...

 

[Perry Babin]

I don't have an answer to all questions. If I think of something, I'll post.

 

[nonprof]

I don't have an answer to all questions. If I think of something, I'll post.

yeah...thanks for your usual help...

 

[Perry Babin]

If you pull the muting transistor (Qx01) for one or more channels, does that affect the pop for the corresponding channel?

Are you using a signal source that's grounded to the same power supply as the amp?

 

[nonprof]

If you pull the muting transistor (Qx01) for one or more channels, does that affect the pop for the corresponding channel?

Are you using a signal source that's grounded to the same power supply as the amp?

I disconnected the four signal path going to the channels but the speakers still pulls back and forth for few millimeters. Pop noise reduces compared if signals are connected.
No signal source yet...but i'm using phones.
I notice that if speaker is connected to bridge terminals, there are NO event of pulling or popping. I suspected that S-GND is fluctuating.

 

[an2ny888]

I wonder if this has something to do with the acoustic compensation circuitry. Is the pop louder with the acoustic conpensation on?

 

[nonprof]

I wonder if this has something to do with the acoustic compensation circuitry. Is the pop louder with the acoustic conpensation on?

Yes, it's louder if acoustic compensation is ON.

 

[Perry Babin]

Confirm that there is no significant DC voltage on the RCA shields. If there is not, connect the shields to the amp ground with a jumper wire. Does that eliminate the pop?