Adcom GFP-565 - Just in Case...... - diyAudio
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Old 6th October 2011, 10:01 PM   #1
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Default Adcom GFP-565 - Just in Case......

This a FYI to anyone new who might have a heart attack when popping the hood on their GFP-565. I just upgrade my power from a Yamaha R9 (it died) to a Adcom GFA-555 and 565 preamp to drive my Polk SDA 2As. When I opened the top on the 565 I noticed mucho brown substance coming from the bottoms of ALL the capacitors (see pics). At 1st glance I cursed because the preamp was in mint condition. Upon 2nd glance (after I had wiped my tears) I found it to be some sort of adhesive used at the bottom of each and every capacitor. Is this normally the way the caps are put down?

O and by the way the Yamaha R9....good riddance! Probably a good receiver but these Polks have been taking it easy for the last 25 years with me. Now they be getting spanked. I know I am at the bottom end of the audiophile bucket equipment wise but I sure don't feel like it! It sounds great......just ask the neighbors.......

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Old 6th October 2011, 10:03 PM   #2
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I believe that the 565s are notorious for leaking and/or exploding caps.

-Charlie
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Old 6th October 2011, 10:09 PM   #3
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Originally Posted by CharlieLaub View Post
I believe that the 565s are notorious for leaking and/or exploding caps.

-Charlie
Hey Charlie. I don't believe these are leaking at all. There are eleven capacitors in the preamp in four different locations. All the spaces where the substance is located have a common area of displaying themselves as shown in the pics. I poked them a little with the end of small screwdriver and it is semi-hard and much like an adhesive.
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Old 7th October 2011, 04:46 AM   #4
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Hello, that does appear to be an adhesive for holding the caps down to the PCB. It's been used fairly regularly since the 70's. I recall demolishing clock radios, walkie-talkies, etc. in the 80's that were 70's era, and they had the same sort of stuff on them. No leakage to speak of.

I haven't heard of the Adcom preamps having issues with leakage from the Electrolytic Caps, but some of the power amps did have issues from what I have read. Especially some of the GFA-555's of certain eras. I suspect that Anatech will have better details about this.

Peace,

Dave
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Old 7th October 2011, 04:58 AM   #5
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Originally Posted by dave_gerecke View Post
Hello, that does appear to be an adhesive for holding the caps down to the PCB. It's been used fairly regularly since the 70's. I recall demolishing clock radios, walkie-talkies, etc. in the 80's that were 70's era, and they had the same sort of stuff on them. No leakage to speak of.

I haven't heard of the Adcom preamps having issues with leakage from the Electrolytic Caps, but some of the power amps did have issues from what I have read. Especially some of the GFA-555's of certain eras. I suspect that Anatech will have better details about this.

Peace,

Dave
Yes Dave we are correct in our statements about the adhesive. It really freaked me out when I first saw it but as soon as I figured it out she got plugged into my Nelson Pass design GFA-555, 1st generation amp. I cannot believe the sound difference in this setup and my old receiver. My music does not sound the same. I just cannot believe that I have missed hearing decent music all these years. Scary thing is now I must go ahead in the near future to a tube setup. It is my destiny. O well it is only money right!

Good to hear from you,
Kevin
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Old 7th October 2011, 05:07 AM   #6
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Hmmm, tube setup? That's one thought. Or you could go look at Pass Diy, and really get bitten by Papa's infectious designs! From what I have read, the Balanced Zen Linestage is similar to the Adcom GFP-750 preamp that Nelson Pass designed for Adcom. And that was Adcom's flagship for more than a few years.

Peace,

Dave

Last edited by dave_gerecke; 7th October 2011 at 05:07 AM. Reason: typo
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Old 7th October 2011, 05:24 AM   #7
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Originally Posted by dave_gerecke View Post
Hmmm, tube setup? That's one thought. Or you could go look at Pass Diy, and really get bitten by Papa's infectious designs! From what I have read, the Balanced Zen Linestage is similar to the Adcom GFP-750 preamp that Nelson Pass designed for Adcom. And that was Adcom's flagship for more than a few years.

Peace,

Dave
Dave I have a brother who is infatuated with tube setups. A few years ago I collected a few to put it lightly and thought what the heck, might as well put them to good use.

I am so new to this game is ain't even funny so I have a lot to learn. My learning curve goes up up and away! I know nothing about amps except what I have learned since buying mine 2 weeks ago. Up until then I owned a receiver that output 100 Watts per channel into 8 ohms. It stopped there. So now I have this monster amp designed by Nelson and I am giddy with it. I will need to learn some things about some things before I take on a DIY Pass project. However I am seriously contemplating asking for a solder station for Bday! Have a good multi-meter and a knowledge of electronics but only enough to be dangerous. I think it looks like a great hobby. (Encrypting file so wife cannot read)

Kevin
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Old 9th October 2011, 02:38 AM   #8
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Hey Kevin, I'm not saying no to the Tubes, as I have so many different things around here I can't criticize anyone. I just figure that perhaps a PassDIY preamp would go well with your GFA-555. Especially when it's similar to a preamp that Papa Pass designed for Adcom.

I also recommended trying something from one of Papa's DIY designs, as he provides some pretty good information about the designs. Check out Pass Diy and start reading!

Peace,

Dave

P.S. Build one of the Pass design preamps. Then get into the tubes also!
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Old 31st December 2011, 10:50 PM   #9
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Hi Kevin,

Please, do you have any tech docs about the R9 that died? I need a Service manual or at least a schematic to try to revive mine. No results searching the net.
Thank you.

Cheers,

Antonio Falcao
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