Help me please, problem with my ALEPH 5

[SNOWCRAB]

Hello everybody,

For some time I have a problem with my 5 ALEPH
(PCB DESIGN).
The right channel, works with a stifled and distorted sound.
I placed a protective kit speaker
against the DC current that goes into default.
Can someone guide me in my troubleshooting?

Best regards.

Thierry BASSAL.

 

[SNOWCRAB]

Hi

Last night i made some tests (see original N PASS Schématic)

OFFSET : 35,2 V

Tension between MOSFET Source Résistor

R41 : 0,61 V
R41 : 0,58 V
R42 : 0,60 V
R66 : 0,58 V
R65 : 0,58 V
R64 : 0,58 V

It must be ok

Tension between INPUT MOSFET Résistor

R11 : 4,83 V it must be ok
R14 : 8,40 V (it seems high ?)

Dont you feel there is a problem with Q1 ?

Regards

Thierry

 

[MEGA_amp]

Just to be safe, I'd re-match and install a new pair Q1, Q2. According to Aleph 5 schema, you should have 4-5 volts across R14.


-john

 

[Bill Fuss]

Looks like Q2 is probably open or bad solder joint. As John said, replace Q1 and Q2 with a new matched pair unless you find a fault in your wiring-soldering.
Bill

 

[SNOWCRAB]

Hello,

According to pass lab design,

I replaced Q1 - Q 2 - Q 3 with new matched IRF9610.

New tests :

V - : - 39 V
V+ : + 39 V

R11 : 4,78 V
R14 : 5,10 V
R40 : 0,61 V
R41 : 0,59 V
R42 : 0,61 V
R64 : 0,60 V
R65 : 0,58 V
R66 : 0,58 V
Z5 : 8,68 V

OFFSET : 100 mV

The sound is always distorded and stifled.

I am lost ...

Thierry.

 

[Bill Fuss]

All your measurements look OK. If one channel works compare more component measurements between channels. Check the components values, look for bad solder joints, look for wiring mistakes, check your pinouts on semiconductors.
Bill

 

[MEGA_amp]

I know it may be trivial; but have you tried swapping the inputs from your source and/or preamp?