Adcom GTP 500 II Scratchy Constantly While Playing

F

Fafaafooie

Active Member
Hey All

I just picked up an Adcom GTP 500 II on CL and when I plug it in to my known good amp and speakers the sound coming out of the speakers is very scratchy almost like the scratchy you get from dirty switches/knobs when you use them but this is constant noise. I wouldn't call it static it's more of a scratchy sounds.
Apparently it's not been used in more than a few years. It actually came with the remote but of course it doesn't work!
It's very hard to get to anything to use Deoxit to try.
Any ideas?
 
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Which main-out are you using - norm or lab? My GTP-500 II didn't work correctly when using lab without using shorting plugs in the norm jacks. Seems strange to me but :dunno:
 
I've tried both and both are bad. Did you mean shorter cables? I've tried a 3' and a 1' and both work fine with my other adcom preamp.
I was able to get some Deoxit on the volume knob and tried to work it in but no change.
 
I meant this:

81KwkL7SraL._AC_SL1500_.jpg
 
Noise on all inputs or just tuner? Noise on headphone jack as well?

I just had to rebuild my 500II remote. Leaky batteries corroded the terminals. Also had to redo the red and black wires to the remote PCB. The remote works perfectly again.
 
Mrv8q said:
...I just had to rebuild my 500II remote. Leaky batteries corroded the terminals. Also had to redo the red and black wires to the remote PCB. The remote works perfectly again.
Click to expand...

I "repaired" my remote too when the battery terminals fell out. Here is a picture of the repair. It works great. I had a leaky battery problem too because I hadn't used the pre in years.

adcom remote.jpg
 
Mrv8q said:
Noise on all inputs or just tuner? Noise on headphone jack as well?

I just had to rebuild my 500II remote. Leaky batteries corroded the terminals. Also had to redo the red and black wires to the remote PCB. The remote works perfectly again.
Click to expand...
I didn't try the headphone jack but CD and both Tape 1/2 had it. I basically got it for free so maybe I send it to the shop and hope it's a cheap fix.
My current GFP 555 II sounds great and I can tell this one sounds better through the crackles.

I got a pretty good stack going....
And no that's not how I keep them. It was an Instagram Moment. IMG_20200516_174848.jpg
 
Fafaafooie said:
Wtf I have never seen one of those. Is that a Bestbuy item or am I going online to find that? It's called a shorting plug? I assume I plug into that before going into preamp?
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Amazon has them. You plug into the RCA jacks labeled norm when using the lab main out on the pre.
 
My issue was that one channel barely had any output. When I put the shorting plugs in both channels worked properly. Right now I have a tube amp plugged into the MAIN OUT norm jacks with no shorting plugs installed. I am pretty sure that when an amp was plugged into the MAIN OUT lab jacks I needed the shorting plugs installed in the MAIN OUT norm jacks in order for both channels to work properly.

Per the manual of the GTP 500 the shorting plugs go into the CD input if it is unused. If the CD is used it says not to put them into MAIN OUT or Tape OUT jacks but any other jacks are fine. The manual for the GTP 500 II doesn't mention shorting plugs at all. So be careful.
 
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Helluva stack there. I’m wondering if there are some cold solder joints going on with the 500 II.
 
Mrv8q said:
Helluva stack there. I’m wondering if there are some cold solder joints going on with the 500 II.
Click to expand...

It is definitely going to need a bench visit. I think i'm going to sell the whole stack I prefer the sound of my Denon POA 2800 vs 5500.
 
I ended up finding out my local speaker repair shop South Florida Speaker Repair (No affiliation) works on vintage components as well and without suggesting a recap changed 3 parts for about $120 and it sounds great and they got the remote working, just not on my Adcom CD player which I was hoping.
They also fixed a Denon DP 60L turntable for me for $75 way less than I expected.
If you are in southeast FL so far these guys have never let me down. Worked on my trusty old Polk 11tl before I realized they fix gear too.
 
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