[Mark D. Zacharias[_3_]]

"J.B. Wood" wrote in message
...
Chuck wrote:
On Mon, 22 Sep 2008 06:42:56 -0400, (J. B. Wood)
wrote:

In article , "J.B. Wood"
wrote:

Hello, all. I have the subject audio preamp/tuner that I purchased way
back in 1991. It has worked flawlessly over the years but yesterday
started randomly power cycling (the unit uses a relay) without operator
intervention. When it's on and feeding the companion GTP-500 II audio
power amp everything works audio-wise except that in addition to the
power cycling, infrared remote control has also been rendered
inoperative. Has anyone seen this or similar behavior in other
products? I currently do not have the service manual. I did unplug
the unit from the AC line for 24+ hours but upon restoring AC power the
problem continues. Thanks for your time and comment.
Hello, and wrt the above I should have said "companion GFA-545 II audio
power amp." Sorry for the confusion. Sincerely,

John Wood (Code 5550) e-mail:
Naval Research Laboratory
4555 Overlook Avenue, SW
Washington, DC 20375-5337



My guess would be an open electrolytic capacitor in the power supply.
I no longer have the service manual for this piece, so if someone
could post the schematic on a website, I could be of more assistance.
Chuck

Thanks so much for the quick response, Chuck. I called Adcom today and
the customer service rep said he would send the service manual free of
charge. That's the kind of support that endures me to a vendor. I
described the problem to him and he thinks it may be a processor. I
would still look for the electrolytic first, though, since these are
often parked near a hot running regulator and dry out over a period of
time. This was a recurring problem I had when I was working on Jerrold
CATV 61-channel set top boxes years ago (the box actually remained "on"
as long as it was plugged into an AC outlet). Sincerely,


Could be a power supply issue as someone else posted, but I do also
sometimes see problems involving the front panel which could cause a similar
symptom.

In the case of some later model Sony direct view TV's for example, flaky
tact switches used for the volume, channel, etc would get leaky and cause
their associated functions to trigger randomly or continuously, as well as
disabling the remote...


Mark Z.