Adcom GFA-565

Rich40
Rich40 Posts: 12
edited October 2010 in Troubleshooting
Hi
I have an ADCOM Model GFA-565. The ofset voltage is 6 volts and burned out a speaker. Could you tell me which caps I should replace. I was told to replace the caps in the driver board and the 2 driver transistors. Should i replace the 2 big cap too. I would appreciate any help.
Thanks
Rich
Post edited by Rich40 on
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  • megasat16
    megasat16 Posts: 3,521
    edited August 2010
    Rich40,

    Welcome to Club Polk! I wonder who told you to replace caps and 2 driver transistors. Do you have the service manual for the 565? CP has Adcom experts who can help you for these. Just wait till they see your thread with question.

    I don't know if the 565 is the model people are saying about having factory defects with the big capacitors or not but replacing those BIG caps will do more good and no harm if you have them ready. I am not sure but I think they are 22000uF 100V caps? I saw them on eBay from time to time.
    Trying out Different Audio Cables is a Religious Affair. You don't discuss it with anyone. :redface::biggrin:
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  • agfrost
    agfrost Posts: 2,428
    edited August 2010
    IIRC, you may simply replace caps if it's done as a preventative maintenance job--The 565 is prone to certain caps leaking.

    If those caps have already let go, you're into a more significant repair job that will likely require removing all parts from the affected board(s) followed by painstaking cleaning to remove electrolyte that has leaked.

    The job is beyond my level of expertise, but forum member Ben has done this job before, if you search the archives you should be able to find his thread. He may be in the middle of a move right now, so he may not see this in a timely fashion.

    In any case, welcome to Club Polk and hope you get your Adcom back into action!

    Jay
    Jay
    SDA 2BTL * Musical Fidelity A5cr amp * Oppo BDP-93 * Modded Adcom GDA-600 DAC * Rythmik F8 (x2)
    Micro Seiki DQ-50 * Hagerman Cornet 2 Phono * A hodgepodge of cabling * Belkin PF60
    Preamp rotation: Krell KSL (SCompRacer recapped) * Manley Shrimp * PS Audio 5.0
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  • Rich40
    Rich40 Posts: 12
    edited August 2010
    Hi
    Thanks for the info. The big caps didn't let go. I am not sure where to look for the problem. Any advice as far as what I should do, I would appreciate.
    Thanks
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  • agfrost
    agfrost Posts: 2,428
    edited August 2010
    I don't know that it's the big caps that are the ones that degrade. Browsing around, it seems that the driver board is where the issue lies. There are a few on the board that are more knowledgeable than me, but I'm a master at the search function. :)

    There's some information here: LINK

    and here LINK

    and here: LINK

    Good luck!

    Jay
    Jay
    SDA 2BTL * Musical Fidelity A5cr amp * Oppo BDP-93 * Modded Adcom GDA-600 DAC * Rythmik F8 (x2)
    Micro Seiki DQ-50 * Hagerman Cornet 2 Phono * A hodgepodge of cabling * Belkin PF60
    Preamp rotation: Krell KSL (SCompRacer recapped) * Manley Shrimp * PS Audio 5.0
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  • Rich40
    Rich40 Posts: 12
    edited September 2010
    Hi
    I appreciate the help. Do you think the problem is on the output boards. and do you know where i could by 100v/35.000 cap. I do have a service manual.
    Thanks
    Richard
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  • ben62670
    ben62670 Posts: 15,969
    edited September 2010
    It's not the big caps that go bad. There are some (5) electrolytic that go bad and funk up the input board.
    Please. Please contact me a ben62670 @ yahoo.com. Make sure to include who you are, and you are from Polk so I don't delete your email. Also I am now physically unable to work on any projects. If you need help let these guys know. There are many people who will help if you let them know where you are.
    Thanks
    Ben
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  • fbm211
    fbm211 Posts: 1,488
    edited September 2010
    I had to send mine out for service a few years ago.Almost all of the 565s had a bad batch of caps on the input boards.
    Do you only have one 565?
    I spent quite a bit to get my set repaired and it was worth every penny.The 565 is a great...even legendary amp.
    SDA-2BTL with custom IC
    Adcom 565 monoblocks--Monarchy Audio M-10 preamp
    Theta Data Basic Transport--Stello DA100 Signature DAC--Camelot Dragon Pro2 MK III
    Harman Kardon T-55c TT
    DH Labs Q-10 Signature Speaker Cables With Furez silver plated copper bananas
    Revelation Audio Labs Prophecy Cryo-Silver Reference AES/EBU
    Revelation Audio Labs Prophecy Cryo-Silver i2s digital cable
    4 Furutech FP-314Ag with FI-11cu Plugs/FI-11AG IECs--- Power Cords
    DH LABS REVELATIONS ICs-amps
    Revelation Audio Labs Paradise cryo-silver ICs-Source to pre
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  • Rich40
    Rich40 Posts: 12
    edited September 2010
    Hi
    I found the 4 electrolytics on the input board. I am going to replace them. I don't see andy leakage from them. Do you think I should replace anything else. Thanks for the info
    Richard
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  • ben62670
    ben62670 Posts: 15,969
    edited September 2010
    You won't see the leakage on the board. You will smell it when de soldering them. Rich where do you live?
    Please. Please contact me a ben62670 @ yahoo.com. Make sure to include who you are, and you are from Polk so I don't delete your email. Also I am now physically unable to work on any projects. If you need help let these guys know. There are many people who will help if you let them know where you are.
    Thanks
    Ben
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  • Rich40
    Rich40 Posts: 12
    edited September 2010
    Hi
    I live in Lock haven Pa. Do I still have to do anything with the board. Will I see the leakage. Do you think i should replace anything else. Thanks for all of you help.
    Richard
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  • agfrost
    agfrost Posts: 2,428
    edited September 2010
    Ah, we've got Ben into this thread now; you're in good hands.
    Jay
    SDA 2BTL * Musical Fidelity A5cr amp * Oppo BDP-93 * Modded Adcom GDA-600 DAC * Rythmik F8 (x2)
    Micro Seiki DQ-50 * Hagerman Cornet 2 Phono * A hodgepodge of cabling * Belkin PF60
    Preamp rotation: Krell KSL (SCompRacer recapped) * Manley Shrimp * PS Audio 5.0
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  • hearingimpared
    hearingimpared Posts: 21,137
    edited September 2010
    Yep and I think Brock should be weighing in soon too. My 565s didn't have that problem because they had the super duper deluxe silver whatever upgrades done by Musical Concepts and those mods made those 565s something special.

    Rich40 perhaps you might like to check out the mods here;

    http://www.musicaldesign.com/MC_AdcomAmp_mods.html
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  • Rich40
    Rich40 Posts: 12
    edited September 2010
    Hi
    I am going to try an remove the cap. I hope without a problem.
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  • Rich40
    Rich40 Posts: 12
    edited September 2010
    Hi
    I replaced the 5 caps on the input driver board. The ofset voltage is still way to high. I need some advice.
    Richare
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  • Rich40
    Rich40 Posts: 12
    edited September 2010
    Hi
    This is Richard again, Whn I set my meter at 200 volts it red 72. Does that sound right
    Thanks
    Richard
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  • FTGV
    FTGV Posts: 3,649
    edited September 2010
    Rich40 wrote: »
    When I set my meter at 200 volts it red 72. Does that sound right
    Not if your reading 72 volts DC at the output:eek:

    You should wander over to Diyaudio and do a search for 565 threads or register and ask the resident Adcom experts there about your issue.

    btw here is a service manual that may be helpful.Though some schematics apppear to be missing. http://www.schematicsunlimited.com/download.php?manu=adcom&file=adcom-gfa565-power-amplifier-service-manual.pdf
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  • Rich40
    Rich40 Posts: 12
    edited September 2010
    Hi
    I took all 5 output transistors of the one board, because i was getting a short reading across all of the emiter and base. The transistors all checked good. The board on the other side then checked normal. When i metered the base emiter and emitor ancolector, the board still showed shorted.
    What do you think
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  • Rich40
    Rich40 Posts: 12
    edited September 2010
    Hi
    I told you wrong. The colector to base or emitor is ok. base to emitor reads 18 ohms. I amm no sure if this is normal or not. All of the 5 outputs check good.
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  • Rich40
    Rich40 Posts: 12
    edited October 2010
    Hi
    I am seeking information on where I could find a front for a heathkit AR1500 receiver. I would appreciate any help or advice
    Thank
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  • agfrost
    agfrost Posts: 2,428
    edited October 2010
    Go ahead and start a new topic, you're not going to draw eyes to it in this thread.
    Jay
    SDA 2BTL * Musical Fidelity A5cr amp * Oppo BDP-93 * Modded Adcom GDA-600 DAC * Rythmik F8 (x2)
    Micro Seiki DQ-50 * Hagerman Cornet 2 Phono * A hodgepodge of cabling * Belkin PF60
    Preamp rotation: Krell KSL (SCompRacer recapped) * Manley Shrimp * PS Audio 5.0
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  • Rich40
    Rich40 Posts: 12
    edited October 2010
    Hi
    Sorry about that
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