sinus live sla-1500 repair need help

[Ground Zero]

Hello

I create a new post about my problem of pop noise with the mono amplifier sinuslive SLA1500 "Rev A"

the old post
SinusLive SL-A1500 help needed.

I prefer to create a new post because this will be more easy to understand and now i have a 2x20mhz scope

I remember you The problem:

When i turn on the amplifier i can here a "pop, noise" in the speaker, the pop noise appear in the same time when the power on led bright, there is no input rca connected.

For the first start of the amp "capacitors are not charged"
with no speaker connected to the terminal i have ~2.5 vdc and the voltage go down to zero volts and grow to -177mv dc -178mv dc - 179mv dc slowly and seems don't stop

For the second start of the amp with no speaker connected,
the dc voltage start from zero vdc to -172mv dc, - 177mv dc etc slowly and seems don't stop.....but after one or two minutes i have -192mv dc

the pop noise is more important during the first start of the amp when rail capacitors are not charged.

I also seen when i touch the bass boost potentiometer, i can here a noise like a scratch....

Could you help me to resolve the problem please?

thanks in advance

[Perry Babin]

The potentiometer may only need cleaning.

Is this a loud pop or simply the click produced by 175mv of DC offset?

Do you see a large spike on the output at the time of the pop?

[Ground Zero]

Hello Perry

Thanks for your answer

For the first start of the amp "rail capacitors are empty" I can here a loud pop in the speakers with fast click in the supply off the amp.

i power off the amp

For the second start i can here the click produced by the 175mv dc offset

Theses test are not in the car but if i put the amp in the car i alway here a loud pop...

By spike did you mean the cone of the speaker go up ?

[Perry Babin]

Looking at the signal on the speaker output terminal with your scope, do you see a large voltage spike when it pops loudly?

How far does the spike swing (2.5v, 20v, 50v...)?

How long is the delay between the time that you apply remote voltage and the time that amp pops?

To clarify, does the amp pop loudly EVERY time you power it on in the vehicle but only once when you initially power it up on the bench?

[Ground Zero]

the scope is set to dc voltage, with 2 volts / div and 0.5 time / div
I 've seen about 2.5volts spike when it pop.

the delay between the time i apply the remote voltage before pop appear is about 4 seconds.

The amp pop loudly every time i power it on the bench and in the car but sometimes the pop noise is less loud in the car and the sometimes the pop noise is very loud .

I have other amp in my car and i only have problem of pop with this one.

[Perry Babin]

I think you'll find that the rail caps are fully charged well before it pops.

Solder a jumper between pins 1 and 2 on the driver module? Make sure it's pins 1 and 2. Pin 2 is directly connected to the negative speaker terminal. With that jumper in place, does the amp pop?

Did you ever trace the rest of the circuit (I think it was for the subsonic filter)?

[Ground Zero]

could you tell me please, where is pin 1 and 2 on the modu1 driver board ?

Yes the amp have a subsonic filter and i don't test other things because i don't really know what can produce this noise so i don't know how to proceed it's why i need your help please.

thanks

[Ground Zero]

i find pin 1 and 2 and i solder a jumper, but the pop noise is here !

and i also hear a strange noise in the amp or in the speaker i'm not sure, like a sweep frequency in continu and grow up or stabilizes...


This is the picture of modu1 from the service manual



I also mesured the output voltage from pin 11, 10 and i have 1.70 vdc and on pins 7, 6, i have 2.40vdc is it normal ? because it seems to go to mosfet is it right ? so why voltage are differents ?

[Perry Babin]

Does it pop precisely as it did before or did shorting pins 1 and 2 make the pop change?

Only 2 of the outputs from the driver module are used.

[Ground Zero]

The amp pop like it did before but shorting pin 1 and 2 seem to stress the supply of the amp

So what can i do ?

Thanks