"William R. Walsh" m
wrote in message ...
Hello all...

I was all of bored and inspired by reports of these stereo receivers going
up in sparks and smoke from time to time to see what was inside this
stereo
receiver and how well it was put together. I think they're actually a
decent
piece of equipment as long as they're not abused or the specifications
violated. The following web page is the result:

http://greyghost.mooo.com/rx4109takeapart/

This also applies to the Insignia NS-R2000 sold by Best Buy, possibly
other
receivers produced by Sherwood with other names on them, and the RX-4105
model.

While not strictly related to the repair of electronics, maybe it would
help
someone in such an effort. I'd greatly appreciate *constructive* comments,
suggestions and clarifications...especially for the section on the audio
amplifier, where I have only the most rudimentary understanding of what is
going on.

Does anyone have the Sherwood RX-4109 service manual kicking around? I'd
gladly pay for one and/or provide a valid e-mail address to which it could
be sent. (Sherwood hasn't responded to me in two days, and I have reason
to
believe that none of the e-mail addresses on their site really work. I
haven't broken down and called them. Yet.)

William



I've seen several models that have a similar look inside. Denon uses the
same chinese vendor and has for years. I've seen it on lower end Pioneers -
not their high-end mind you. They are mostly OK to service if you have the
service literature; frequently they will have a "special" bias transistor,
like a 2SC3964 or a 2SD947. Not the type of thing one normally stocks unless
maybe you do a lot of audio, like I do.

Most use the infamous Denon .22 ohm small emitter resistors, 4 per channel.
Some later ones have gone to a more traditional .47 version, still
paralleled 2+2 on each channel.
I will literally order the .22 versions 50 at a time, since they are only
..15 ea from Denon, and I go through so many of them. You have to replace all
4 if the channel blows, even if one or two check "good". They'll come back
to bite you.

The mid-fi Denon and cheap Pioneer versions generally use the 2SB1560 and
2SD2390. Higher powered models often use the 2SB1647 and 2SD2560.

Mark Z.