Jamo A-101 Sub Amp

[nissam72]

Re: Jamo A-101 Sub Amp

Good morning Dear,

Finally after a long time I have removed glues from the PCB, but still having same problem, is it possible to replace PWM IC?

Kind Regards,

Nissam.

[budm]

Re: Jamo A-101 Sub Amp

So can you read the P/N as printed for that Gate driver IC U2?

[nissam72]

Re: Jamo A-101 Sub Amp

So can you read the P/N as printed for that Gate driver IC U2?

There is no number..

[Agent24]

Re: Jamo A-101 Sub Amp

Don't you just love it when they do that?

If you can draw up a schematic of what pins of the IC connect to what, maybe someone can figure out what it might be. They're probably using a fairly well-known part.

[rievax_60]

Re: Jamo A-101 Sub Amp

I have handled a Jamo SUB250 unit and it has a variation of an "old school" computer power supply circuit (self oscillating) - the A-101 should be of the same variant mentioned thereof.

I just opened up a Jamo SUB250 also. I can confirm that the SMPS really is a self oscillating half bridge using a pair of IRF730 MOSFETs which were shorted.

I sent Jamo a message via their Facebook page expressing my annoyance that their products are failing prematurely because of the yellow glue.

[rievax_60]

Re: Jamo A-101 Sub Amp

Good morning Dear,

Finally after a long time I have removed glues from the PCB, but still having same problem, is it possible to replace PWM IC?

Kind Regards,

Nissam.

U2 looks like it has built in high/low side drive. It might be a type of control IC that is normally found in something like the inverter in a CCFL lamp.

[rievax_60]

Re: Jamo A-101 Sub Amp

This looks right, https://cdn.badcaps-static.com/pdfs/...345f70bf55.pdf

[Huub88]

Re: Jamo A-101 Sub Amp

Hello everyone,

I'm new to this forum and I registered because of this thread. I have a jamo a101 sub that stopped working overnight. The standby circuit is powered as far as I can tell, it just won't switch on when I apply an audio signal. How is the sub amp supposed to come out of standby?

Thank in advance

[sreeraj m]

Re: Jamo A-101 Sub Amp

I have a jamo a101 sub that stopped working.i need to know the MOSFETs details in frond of the 100V 470 uf cap side

[budm]

Re: Jamo A-101 Sub Amp

I have a jamo a101 sub that stopped working.i need to know the MOSFETs details in frond of the 100V 470 uf cap side

What is the P/N as printed on the body?

[tothta75]

Re: Jamo A-101 Sub Amp

Halo,

could anyone tell me please, what should I use to remove the discoloured glue?
(I am a REAL beginner in electronics. Never repaired anything :-) )

THX:
Tamás

[jesgatt]

Re: Jamo A-101 Sub Amp

This looks right, https://cdn.badcaps-static.com/pdfs/...345f70bf55.pdf

Hi, I know that this post is a bit old, but is this the part number for the PWM controller? I tried IR21531D (which is quite similar) but the IC seems to not provide any oscillations (Note: I changed the IRF740 to P10NK60, since they were shorted).

Thanks

[Jicisson]

Re: Jamo A-101 Sub Amp

Bonjour,
Je suis dans le cas #2 ou les traces de coulures sont sur ma pcb. Il y a des traces de surchauffe au niveau des transistors, comme sur la photo.
Est-il possible d'avoir les valeurs des condensateurs et des transistors concernés ?
Merci de votre aide.
Jicisson

[Tannie]

Hi all,
Today I recieved a Jamo A101 subwoofer.
The problem was it did not work at all. The switched power supply did not start oscillating. After measuring I noticed the feedback optocoupler was not switching. After checking some caps I finally found a defective Schottky diode. This one was fully shorted.
See backside of PCB here below. I have marked de culpritt diode in red. It is a SS16 diode. After replacing it, the subwoofer works well again.