AR ARS112PS Subwoofer - Hum

[RichK]

Hi,

This subwoofer is not that old and developed a hum, even with no signal
going in.

It was made in China - you guessed it. Do not have a schematic. Pulled the
ckt assembly out. Workmanship is ugly, but do not see anything obvious.
The ckt bd smells a bit , but it could be how these things smell

There are 2 large caps 63V 6800uF in the PS. Would that be the culprit?

Regards,

Rich

 

[Charles Schuler]

Hi,

This subwoofer is not that old and developed a hum, even with no signal
going in.

It was made in China - you guessed it. Do not have a schematic. Pulled
the
ckt assembly out. Workmanship is ugly, but do not see anything obvious.
The ckt bd smells a bit , but it could be how these things smell

There are 2 large caps 63V 6800uF in the PS. Would that be the culprit?

Most likely.

 

[RichK]

Most likely.

Anyone know where to get these? Googled a lot, but do not see many
suppliers.

Rich

 

[DaveM]

Anyone know where to get these? Googled a lot, but do not see many
suppliers.

Rich

Coming in late on the thread, ... didn't see your original post. How loud
is the hum? Can you hear any audio getting through?
I repaired a powered subwoofer last year that exhibited a loud hum, but no
audio was getting through. Turned out that one of the output transistors
had shorted C-E and was causing extreme stress on the power supply.
Replacing both output transistors fixed the problem.

--
Dave M
MasonDG44 at comcast dot net (Just substitute the appropriate characters in
the address)

Never take a laxative and a sleeping pill at the same time!!

 

[Charles Schuler]

Anyone know where to get these? Googled a lot, but do not see many
suppliers.

Mouser # 5985-85A-80V6800

http://www.mouser.com/?handler=data...+uf&Ntt=*6800*+*uf*&crc=false&Ns=SField&N=111

Also, as the other gent said, you could have a large drain on the supply
(bad output transistors).

 

[RichK]

Thanks for the hint Dave, it got me back to it. I was about to order caps
(thanks for link Charles), but got back to more testing. The output
transistors were OK, by VOM method. I started re-soldering some of the
suspicious joints, as the whole thing did not show good workmanship. Also
tightened the grounding screws. In that process I fixed the problem.

For those wondering, AR (Acoustic Research) is just a name anymore. Not
even sure who owns the name. Stuff is made in China, and not very well at
that.

Rich