Adcom GFA 5500 produces static

bored184
bored184 Posts: 324
edited June 2014 in Electronics
I just recently bought and Adcom GFA-5500. At start up it sounds greats but after about 10-15minutes both channels start to distort. No distortion light comes on and no thermal protection light comes on. Also I notice the left side of the amp is a little warmer then the right. Any ideas?
Speakers: TL Monitor 10s, RTA 11TLs, Fortes, Thiel CS 1.2
Amplifiers: ]Ashly FTX 2001 III, Dynaco ST-70, DIY F6
Pre: Adcom GFP 750, Aikido Tube Pre
Post edited by bored184 on
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  • ZLTFUL
    ZLTFUL Posts: 5,650
    edited June 2014
    Physical grounds...loose nuts. Also, potentially some weak solder joints.
    "Some people find it easier to be conceited rather than correct."

    "Unwad those panties and have a good time man. We're all here to help each other, no matter how it might appear." DSkip
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  • bored184
    bored184 Posts: 324
    edited June 2014
    ZLTFUL wrote: »
    Physical grounds...loose nuts. Also, potentially some weak solder joints.

    I am a little confused though, why would a loose ground developed static in both channels 10-15 minutes into playing? I thought a loose ground would cause static from the beginning.
    Speakers: TL Monitor 10s, RTA 11TLs, Fortes, Thiel CS 1.2
    Amplifiers: ]Ashly FTX 2001 III, Dynaco ST-70, DIY F6
    Pre: Adcom GFP 750, Aikido Tube Pre
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  • ZLTFUL
    ZLTFUL Posts: 5,650
    edited June 2014
    Amp warms up, tolerances change...

    I have a GFA-5503 that had hum on 2 of the 3 channels. Would only show up after 15 or more minutes.
    Took it to my tech who found like 4 loose grounds and 3 solder joints that were suspect. After he fixed those and tightened up the grounds, the only noise is normal noise floor from the amp.
    Just throwing out a suggestion that worked for me. Take it for what it is.
    "Some people find it easier to be conceited rather than correct."

    "Unwad those panties and have a good time man. We're all here to help each other, no matter how it might appear." DSkip
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  • bored184
    bored184 Posts: 324
    edited June 2014
    ZLTFUL wrote: »
    Amp warms up, tolerances change...

    I have a GFA-5503 that had hum on 2 of the 3 channels. Would only show up after 15 or more minutes.
    Took it to my tech who found like 4 loose grounds and 3 solder joints that were suspect. After he fixed those and tightened up the grounds, the only noise is normal noise floor from the amp.
    Just throwing out a suggestion that worked for me. Take it for what it is.

    I appreciate it believe me I just never never knew a ground issue could do that. When I opened this amp up there was quite a bit of rust on some of the connections. I will open it up again and and look to see if I missed anything or accidentally loosened anything while I was in there cleaning.
    Speakers: TL Monitor 10s, RTA 11TLs, Fortes, Thiel CS 1.2
    Amplifiers: ]Ashly FTX 2001 III, Dynaco ST-70, DIY F6
    Pre: Adcom GFP 750, Aikido Tube Pre
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  • ZLTFUL
    ZLTFUL Posts: 5,650
    edited June 2014
    It was frustrating to say the least. I though maybe the amp boards had issues but he took video of the points he repairs to show me after the fact.
    The 5500 and the 5503 are "new" enough that unless it was abused, the caps shouldn't need any attention.
    "Some people find it easier to be conceited rather than correct."

    "Unwad those panties and have a good time man. We're all here to help each other, no matter how it might appear." DSkip
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  • Polkie2009
    Polkie2009 Posts: 3,834
    edited June 2014
    bored184 wrote: »
    I appreciate it believe me I just never never knew a ground issue could do that. When I opened this amp up there was quite a bit of rust on some of the connections. I will open it up again and and look to see if I missed anything or accidentally loosened anything while I was in there cleaning.
    Rust huh? Was the amp stored out in a garage or attic for awhile?
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  • bored184
    bored184 Posts: 324
    edited June 2014
    Polkie2009 wrote: »
    Rust huh? Was the amp stored out in a garage or attic for awhile?
    It was stored in a garage for over a year. He said he had dehumidifiers running.
    Speakers: TL Monitor 10s, RTA 11TLs, Fortes, Thiel CS 1.2
    Amplifiers: ]Ashly FTX 2001 III, Dynaco ST-70, DIY F6
    Pre: Adcom GFP 750, Aikido Tube Pre
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  • [Deleted User]
    [Deleted User] Posts: 10,716
    edited June 2014
    Well, my Crown amps have never had that particular problem...
    I wish I could help.
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  • bored184
    bored184 Posts: 324
    edited June 2014
    I took the amp downstairs and placed it in a new setup, no hum developed down there. I am beginning to think though something has happened in this old duplex my wife and I are renting. I am picking up hums in my audio gear that I have never heard before.
    Speakers: TL Monitor 10s, RTA 11TLs, Fortes, Thiel CS 1.2
    Amplifiers: ]Ashly FTX 2001 III, Dynaco ST-70, DIY F6
    Pre: Adcom GFP 750, Aikido Tube Pre
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  • EndersShadow
    EndersShadow Posts: 17,590
    edited June 2014
    bored184 wrote: »
    I took the amp downstairs and placed it in a new setup, no hum developed down there. I am beginning to think though something has happened in this old duplex my wife and I are renting. I am picking up hums in my audio gear that I have never heard before.

    John... I know your like me and cheap. Pickup one of these babies for your gear and you should be fine.

    http://www.rakuten.com/prod/furman-sound-ac-215a-line-conditioner-ac-noise-ac-surge-over-voltage/215887528.html

    You can run a audioquest multi plug or signal cable multi outlet off it and have enough plugs for your gear.

    And you can be 100% sure you wont be current limited with this thing.
    "....not everything that can be counted counts, and not everything that counts can be counted." William Bruce Cameron, Informal Sociology: A Casual Introduction to Sociological Thinking (1963)
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  • bored184
    bored184 Posts: 324
    edited June 2014
    EndersShadow wrote: »
    John... I know your like me and cheap. Pickup one of these babies for your gear and you should be fine.

    http://www.rakuten.com/prod/furman-sound-ac-215a-line-conditioner-ac-noise-ac-surge-over-voltage/215887528.html

    You can run a audioquest multi plug or signal cable multi outlet off it and have enough plugs for your gear.

    And you can be 100% sure you wont be current limited with this thing.

    The wiring in this old place is 2 prong. I can only imagine what it would look like if I actually delved into the wiring of his place.
    Speakers: TL Monitor 10s, RTA 11TLs, Fortes, Thiel CS 1.2
    Amplifiers: ]Ashly FTX 2001 III, Dynaco ST-70, DIY F6
    Pre: Adcom GFP 750, Aikido Tube Pre
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  • EndersShadow
    EndersShadow Posts: 17,590
    edited June 2014
    bored184 wrote: »
    The wiring in this old place is 2 prong. I can only imagine what it would look like if I actually delved into the wiring of his place.

    LOL... then I would be VERY CAREFUL about plugging stuff in lol...
    "....not everything that can be counted counts, and not everything that counts can be counted." William Bruce Cameron, Informal Sociology: A Casual Introduction to Sociological Thinking (1963)
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