Adcom GTP-500 II

[J.B. Wood]

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.

 

[Chuck]

On Mon, 22 Sep 2008 06:42:56 -0400, wood@itd.nrl.navy.mil (J. B. Wood)
wrote:

In article <gb6bcj$m11$1@ra.nrl.navy.mil>, "J.B. Wood"
john.wood@nrl.navy.mil> 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: wood@itd.nrl.navy.mil
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

 

[J.B. Wood]

Chuck wrote:

On Mon, 22 Sep 2008 06:42:56 -0400, wood@itd.nrl.navy.mil (J. B. Wood)
wrote:

In article <gb6bcj$m11$1@ra.nrl.navy.mil>, "J.B. Wood"
john.wood@nrl.navy.mil> 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: wood@itd.nrl.navy.mil
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,