Adcom Gtp-500ii Fm Problem

sandstorm33 · 11th April 2008, 05:20 PM

Have chance to get GTP-500II FM tuner/preamp cheap. Has intermittent FM delivery..told this is common when unit ages ..Anyone have experience with this unit/problem??????

sandstorm33 · 11th April 2008, 05:23 PM

Anyone have a schematic??

Westley · 11th April 2008, 05:51 PM

This was a common problem that invloves the replacement of the FM trimmer capacitor. I seem to remember it being C4 but that was 15 years ago so I'll check the manual when I get home. It is a very simple repair.

Ty_Bower · 28th April 2008, 08:45 PM

Did you ever get a chance to check that service manual?

TerryC · 30th May 2008, 09:33 PM

The part # is CT-104, and it is located inside the metal box. I've made this repair successfully multiple times using Mouser P/N 659-GKG10015. Once replaced, you will need a DVM to bring the circuit back into alignment. I can provide instructions for performing the alignment.

sweiss1966 · 16th June 2008, 06:22 AM

My GTP-500II just started experiencing this the intermittent FM reception problem... Can you post those instructions on how to re-align the FM Tuner after replacing the cap?

gregbed · 27th June 2008, 01:19 PM

This website has all the details.

http://www.vgernet.net/bks0731/comms/adcom.html

TerryC · 27th June 2008, 04:15 PM

From the service manual....

http://i41.photobucket.com/albums/e2...500IIAlign.jpg

Don't attempt beyond steps 1 & 2 unless you have the specialized equipment.

gregbed · 7th July 2008, 01:00 AM

Terry C
I am trying to do this repair for the first time. I have a solid metal cage around FM section. It looks like the top is soldered on. How do open this? Do you just desolder the corners and inside side and pry it open? Any tips or tricks would be appreciated.
Greg

TerryC · 7th July 2008, 02:38 AM

Quote:

Originally posted by gregbed
Terry C
I am trying to do this repair for the first time. I have a solid metal cage around FM section. It looks like the top is soldered on. How do open this? Do you just desolder the corners and inside side and pry it open? Any tips or tricks would be appreciated.
Greg

Yes, one corner at a time. Any cheap soldering iron with a large tip will work. I used some wick to get the majority of the solder off, then heat it up again and pry it open.

11th April 2008, 05:20 PM	#1
sandstorm33 diyAudio Member Join Date: Sep 2006	Adcom Gtp-500ii Fm Problem Have chance to get GTP-500II FM tuner/preamp cheap. Has intermittent FM delivery..told this is common when unit ages ..Anyone have experience with this unit/problem??????

16th June 2008, 06:22 AM	#6
sweiss1966 diyAudio Member Join Date: Jun 2008	Can you post those alignment instructions? My GTP-500II just started experiencing this the intermittent FM reception problem... Can you post those instructions on how to re-align the FM Tuner after replacing the cap?

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11th April 2008, 05:23 PM	#2
sandstorm33 diyAudio Member Join Date: Sep 2006	Anyone have a schematic??

11th April 2008, 05:51 PM	#3
Westley diyAudio Member Join Date: Mar 2007	This was a common problem that invloves the replacement of the FM trimmer capacitor. I seem to remember it being C4 but that was 15 years ago so I'll check the manual when I get home. It is a very simple repair.

28th April 2008, 08:45 PM	#4
Ty_Bower diyAudio Member Join Date: Mar 2007 Location: Newark, DE	Did you ever get a chance to check that service manual?

30th May 2008, 09:33 PM	#5
TerryC diyAudio Member Join Date: Jun 2005 Location: WA-USA	The part # is CT-104, and it is located inside the metal box. I've made this repair successfully multiple times using Mouser P/N 659-GKG10015. Once replaced, you will need a DVM to bring the circuit back into alignment. I can provide instructions for performing the alignment.

27th June 2008, 01:19 PM	#7
gregbed diyAudio Member Join Date: Jun 2008	This website has all the details. http://www.vgernet.net/bks0731/comms/adcom.html

27th June 2008, 04:15 PM	#8
TerryC diyAudio Member Join Date: Jun 2005 Location: WA-USA	From the service manual.... http://i41.photobucket.com/albums/e2...500IIAlign.jpg Don't attempt beyond steps 1 & 2 unless you have the specialized equipment.

7th July 2008, 01:00 AM	#9
gregbed diyAudio Member Join Date: Jun 2008	Terry C I am trying to do this repair for the first time. I have a solid metal cage around FM section. It looks like the top is soldered on. How do open this? Do you just desolder the corners and inside side and pry it open? Any tips or tricks would be appreciated. Greg

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