Fixing an Adcom GFA 555

pablo_rodz
pablo_rodz Posts: 331
edited August 2009 in Electronics
Hi all,

I just got a used Adcom GFA 555, it looks different to all the 555's I've seen, so I think it's kind of old.

The amp was cheap because the right channel RCA Jack is broken. I thought it was going to be an easy and cheap fix, but the two (2) RCA inputs are in one plastic unit. I need help finding a new RCA jack "thingy". At least the amp powers up and seems to work.

Below are pictures of the amp opened up and the RCA jack plastic unit/thingy :confused:

It looks clean, the caps are not swollen or leaking everything looks great.

CIMG2901.jpg

CIMG2902.jpg

The broken Right Channel RCA Jack
CIMG2908.jpg

The back of the RCA jacks
CIMG2909.jpg

The plastic RCA jack unit
CIMG2912.jpg

This is where the RCA's are soldered to the board
CIMG2913.jpg

CIMG2905.jpg

CIMG2903.jpg
HT:
Projector - JVC HD100, 100" Fixed Screen, A/V Receiver - Pioneer Elite VSX-92TXH, Power Conditioner - Panamax M5300-EX, BluRay - Sony PS3, (2) ADCOM GFA 555 Bridged, Speakers - LSi 15, LSi C, LSi FX, Sub - 12" M&K VX-1250.

Living Room:
Schiit Saga, Parasound HCA-600, OPPO BDP-103D, LSi7
Post edited by pablo_rodz on
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  • AudioGenics
    AudioGenics Posts: 2,567
    edited July 2009
    check out

    http://www.parts-express.com/home.cfm
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  • cnh
    cnh Posts: 13,284
    edited July 2009
    Don't most older GFA-555s just have TWO large Blue 30kmfs CAPS not four? So are those new mods to that unit?

    cnh
    Currently orbiting Bowie's Blackstar.!

    Polk Lsi-7s, Def Tech 8" sub, HK 3490, HK HD 990 (CDP/DAC), AKG Q701s
    [sig. changed on a monthly basis as I rotate in and out of my stash]
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  • pablo_rodz
    pablo_rodz Posts: 331
    edited July 2009
    jvc wrote: »
    check out

    http://www.parts-express.com/home.cfm

    I did check PE, but the RCA jacks they have are for chassis mount, I need the plastic RCA pad (L+R in one). If I cannot find it I'll have to rig-up something:confused:
    HT:
    Projector - JVC HD100, 100" Fixed Screen, A/V Receiver - Pioneer Elite VSX-92TXH, Power Conditioner - Panamax M5300-EX, BluRay - Sony PS3, (2) ADCOM GFA 555 Bridged, Speakers - LSi 15, LSi C, LSi FX, Sub - 12" M&K VX-1250.

    Living Room:
    Schiit Saga, Parasound HCA-600, OPPO BDP-103D, LSi7
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  • pablo_rodz
    pablo_rodz Posts: 331
    edited July 2009
    cnh wrote: »
    Don't most older GFA-555s just have TWO large Blue 30kmfs CAPS not four? So are those new mods to that unit?

    cnh

    I have no Idea, the guy that sold it to me had no info. on it, he even asked what I wanted it for :eek:, that he had no idea why will some one need one...:rolleyes:
    HT:
    Projector - JVC HD100, 100" Fixed Screen, A/V Receiver - Pioneer Elite VSX-92TXH, Power Conditioner - Panamax M5300-EX, BluRay - Sony PS3, (2) ADCOM GFA 555 Bridged, Speakers - LSi 15, LSi C, LSi FX, Sub - 12" M&K VX-1250.

    Living Room:
    Schiit Saga, Parasound HCA-600, OPPO BDP-103D, LSi7
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  • cnh
    cnh Posts: 13,284
    edited July 2009
    I may have been wrong about those caps....perhaps it is 4 X 15K. And 16 small caps.

    See this link for a photo to compare with yours.

    http://www.polkaudio.com/forums/attachment.php?attachmentid=16755&d=1148038682

    cnh
    Currently orbiting Bowie's Blackstar.!

    Polk Lsi-7s, Def Tech 8" sub, HK 3490, HK HD 990 (CDP/DAC), AKG Q701s
    [sig. changed on a monthly basis as I rotate in and out of my stash]
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  • pablo_rodz
    pablo_rodz Posts: 331
    edited July 2009
    cnh wrote: »
    I may have been wrong about those caps....perhaps it is 4 X 15K. And 16 small caps.

    See this link for a photo to compare with yours.

    http://www.polkaudio.com/forums/attachment.php?attachmentid=16755&d=1148038682

    cnh


    that is correct it has (Capacitor Technologies) 4 x 15000 MFD 80 WVDC
    and 16 Toshiba small caps.

    Does someone knows what does this mean on the Toroidal Transformer:confused: 01124 708 VA 11 85 ???
    HT:
    Projector - JVC HD100, 100" Fixed Screen, A/V Receiver - Pioneer Elite VSX-92TXH, Power Conditioner - Panamax M5300-EX, BluRay - Sony PS3, (2) ADCOM GFA 555 Bridged, Speakers - LSi 15, LSi C, LSi FX, Sub - 12" M&K VX-1250.

    Living Room:
    Schiit Saga, Parasound HCA-600, OPPO BDP-103D, LSi7
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  • pablo_rodz
    pablo_rodz Posts: 331
    edited July 2009
    Anyone??
    Does anyone know where I can find a dual RCA jack?
    HT:
    Projector - JVC HD100, 100" Fixed Screen, A/V Receiver - Pioneer Elite VSX-92TXH, Power Conditioner - Panamax M5300-EX, BluRay - Sony PS3, (2) ADCOM GFA 555 Bridged, Speakers - LSi 15, LSi C, LSi FX, Sub - 12" M&K VX-1250.

    Living Room:
    Schiit Saga, Parasound HCA-600, OPPO BDP-103D, LSi7
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  • Bigbang
    Bigbang Posts: 233
    edited July 2009
    you might try and contact this guy...

    http://www.alibaba.com/product-gs/50034743/RCA_Jack.html

    or better yet save up some cash and send it to these guys...

    http://www.musicaldesign.com/adcom.htm

    or at least call them and see if you can source that part somewhere...

    David
    I like to listen, tinker, listen and repeat.
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  • RandyWilliamson
    RandyWilliamson Posts: 178
    edited July 2009
    Pedro....try:

    www.jameco.com

    they're very likely to have it...u may have to do extensive searching or call them tho.

    Good luck....at worst you can rig one im sure.
    Cool stuff: Adcom GFA-555, GFP-710, Oppo BDP-83, Monitor 10's w/RDO198s, rebuilt and modded XO: Sonicap/Mundorf topside, Daytons Low.
    Benq W5000

    "Leaning back like a maxwell tape commercial listening to pure polk bliss"
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  • pablo_rodz
    pablo_rodz Posts: 331
    edited July 2009
    Bigbang wrote: »
    you might try and contact this guy...

    http://www.alibaba.com/product-gs/50034743/RCA_Jack.html

    or better yet save up some cash and send it to these guys...

    http://www.musicaldesign.com/adcom.htm

    or at least call them and see if you can source that part somewhere...

    David

    Yikes that would be quite a bit of cash:(

    I wonder If I could do some of that myself:eek:
    HT:
    Projector - JVC HD100, 100" Fixed Screen, A/V Receiver - Pioneer Elite VSX-92TXH, Power Conditioner - Panamax M5300-EX, BluRay - Sony PS3, (2) ADCOM GFA 555 Bridged, Speakers - LSi 15, LSi C, LSi FX, Sub - 12" M&K VX-1250.

    Living Room:
    Schiit Saga, Parasound HCA-600, OPPO BDP-103D, LSi7
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  • obieone
    obieone Posts: 5,077
    edited July 2009
    +1. I'm sure Dr. Polkenstein can hook you up.
    I refuse to argue with idiots, because people can't tell the DIFFERENCE!
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  • pablo_rodz
    pablo_rodz Posts: 331
    edited July 2009
    So Ben or Dr. Polkestein are the guys to find??

    But I would like to learn how to do it....
    HT:
    Projector - JVC HD100, 100" Fixed Screen, A/V Receiver - Pioneer Elite VSX-92TXH, Power Conditioner - Panamax M5300-EX, BluRay - Sony PS3, (2) ADCOM GFA 555 Bridged, Speakers - LSi 15, LSi C, LSi FX, Sub - 12" M&K VX-1250.

    Living Room:
    Schiit Saga, Parasound HCA-600, OPPO BDP-103D, LSi7
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  • pablo_rodz
    pablo_rodz Posts: 331
    edited July 2009
    Hi all!

    I just ordered a pair of gold plated RCA Jacks to fix the amp. I couldn't hold my self and decided to hook-up my new Atrium 45 to the amp to see if it works....

    Well the right channel works, music plays fine, but the left channel has a Humm/ buzzing sound. The humm is even present when I remove the Interconnect (cable).

    Does anyone have an idea of what could be causing it?
    HT:
    Projector - JVC HD100, 100" Fixed Screen, A/V Receiver - Pioneer Elite VSX-92TXH, Power Conditioner - Panamax M5300-EX, BluRay - Sony PS3, (2) ADCOM GFA 555 Bridged, Speakers - LSi 15, LSi C, LSi FX, Sub - 12" M&K VX-1250.

    Living Room:
    Schiit Saga, Parasound HCA-600, OPPO BDP-103D, LSi7
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  • pablo_rodz
    pablo_rodz Posts: 331
    edited July 2009
    obieone wrote: »
    +1. I'm sure Dr. Polkenstein can hook you up.

    I tried searching by his name but I got no results...:confused:
    HT:
    Projector - JVC HD100, 100" Fixed Screen, A/V Receiver - Pioneer Elite VSX-92TXH, Power Conditioner - Panamax M5300-EX, BluRay - Sony PS3, (2) ADCOM GFA 555 Bridged, Speakers - LSi 15, LSi C, LSi FX, Sub - 12" M&K VX-1250.

    Living Room:
    Schiit Saga, Parasound HCA-600, OPPO BDP-103D, LSi7
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  • Systems
    Systems Posts: 14,873
    edited July 2009
    pablo_rodz wrote: »

    Does someone knows what does this mean on the Toroidal Transformer:confused: 01124 708 VA 11 85 ???
    Probably part#,VA rating (708)and date code.
    Testing
    Testing
    Testing
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  • Systems
    Systems Posts: 14,873
    edited July 2009
    pablo_rodz wrote: »

    Does anyone have an idea of what could be causing it?
    Possibly a bad filter cap.Also did you make sure to isolate the body of the new RCA connectors from the chassis.
    Testing
    Testing
    Testing
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  • CoolJazz
    CoolJazz Posts: 570
    edited July 2009
    Coupling capacitor maybe or you still have a open signal or cracked ground on that jack? Since you have obvious external damage, I'd focus on that first.

    Coupling caps COULD be something like those round yellow caps that I think I see four of in one of those pictures. Somebody with experience on that amp might be able to send you right to the correct parts in there. Just know what your doing before you poke around in there...those big caps mean business and may hold a charge long after it's off!!

    CoolJazz
    A so called science type proudly says... "I do realize that I would fool myself all the time, about listening conclusions and many other observations, if I did listen before buying. That’s why I don’t, I bought all of my current gear based on technical parameters alone, such as specs and measurements."

    More amazing Internet Science Pink Panther wisdom..."My DAC has since been upgraded from Mark Levinson to Topping."
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  • polrbehr
    polrbehr Posts: 2,830
    edited July 2009
    I'm sure this is who Lasareath is referring to...

    http://www.polkaudio.com/forums/member.php?u=76154

    Ben knows about Adcoms, in fact he's who I bought mine from (GFA555).

    He's also a pretty good guy, but that's just IMHO ;)
    So, are you willing to put forth a little effort or are you happy sitting in your skeptical poo pile?


    http://audiomilitia.proboards.com/
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  • cnh
    cnh Posts: 13,284
    edited July 2009
    Ben is great at exactly this kind of thing among a whole host of others. And offers to help anyone out there who needs it. He knows his stuff.

    When I first got my Adcom, he told me to drop it by and he'd take a look at my caps, etc, if I were down his way. I have a friend in Atlanta and occasionally get down there. I will certainly lug the Adcom down on my next trip.

    Drop Ben a line and get an estimate...and check out your shipping options.

    cnh
    Currently orbiting Bowie's Blackstar.!

    Polk Lsi-7s, Def Tech 8" sub, HK 3490, HK HD 990 (CDP/DAC), AKG Q701s
    [sig. changed on a monthly basis as I rotate in and out of my stash]
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  • dudeinaroom
    dudeinaroom Posts: 3,609
    edited July 2009
    I don't believe those had coupling caps
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  • pablo_rodz
    pablo_rodz Posts: 331
    edited July 2009
    I PM'd Ben....

    Thanks...

    Also, I haven't replaced the RCA jacks, I just ordered them today. How do I discharge the caps, before shocking myself???

    Thanks again!
    HT:
    Projector - JVC HD100, 100" Fixed Screen, A/V Receiver - Pioneer Elite VSX-92TXH, Power Conditioner - Panamax M5300-EX, BluRay - Sony PS3, (2) ADCOM GFA 555 Bridged, Speakers - LSi 15, LSi C, LSi FX, Sub - 12" M&K VX-1250.

    Living Room:
    Schiit Saga, Parasound HCA-600, OPPO BDP-103D, LSi7
    · Share on FacebookShare on Twitter
  • Systems
    Systems Posts: 14,873
    edited July 2009
    dudeinaroom wrote: »
    I don't believe those had coupling caps
    I believe the original version did but the MK11 version omitted them in favour of a servo.
    pablo_rodz wrote: »
    How do I discharge the caps, before shocking myself???

    Thanks again!
    With a >50 ohm 2watt resistor.
    Testing
    Testing
    Testing
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  • RandyWilliamson
    RandyWilliamson Posts: 178
    edited July 2009
    where did u find the part btw?? should this ever so sucky situation arrive....I'd want to know.......
    Cool stuff: Adcom GFA-555, GFP-710, Oppo BDP-83, Monitor 10's w/RDO198s, rebuilt and modded XO: Sonicap/Mundorf topside, Daytons Low.
    Benq W5000

    "Leaning back like a maxwell tape commercial listening to pure polk bliss"
    · Share on FacebookShare on Twitter
  • pablo_rodz
    pablo_rodz Posts: 331
    edited July 2009
    RandyWilliamson wrote: »
    where did u find the part btw?? should this ever so sucky situation arrive....I'd want to know.......

    I havent found the part, I'm going to try to "rig-it up".
    HT:
    Projector - JVC HD100, 100" Fixed Screen, A/V Receiver - Pioneer Elite VSX-92TXH, Power Conditioner - Panamax M5300-EX, BluRay - Sony PS3, (2) ADCOM GFA 555 Bridged, Speakers - LSi 15, LSi C, LSi FX, Sub - 12" M&K VX-1250.

    Living Room:
    Schiit Saga, Parasound HCA-600, OPPO BDP-103D, LSi7
    · Share on FacebookShare on Twitter
  • pablo_rodz
    pablo_rodz Posts: 331
    edited July 2009
    Well I got the RCA Jacks, and solder iron today.... Can't wait for the weekend to "fix" the amp.
    HT:
    Projector - JVC HD100, 100" Fixed Screen, A/V Receiver - Pioneer Elite VSX-92TXH, Power Conditioner - Panamax M5300-EX, BluRay - Sony PS3, (2) ADCOM GFA 555 Bridged, Speakers - LSi 15, LSi C, LSi FX, Sub - 12" M&K VX-1250.

    Living Room:
    Schiit Saga, Parasound HCA-600, OPPO BDP-103D, LSi7
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  • pablo_rodz
    pablo_rodz Posts: 331
    edited July 2009
    pablo_rodz wrote: »
    Can't wait for the weekend to "fix" the amp.

    Well that didn't work! :(

    The HUMM is still present, and louder.:confused:

    I tried PMing Ben, but his PM's are maxed out!
    HT:
    Projector - JVC HD100, 100" Fixed Screen, A/V Receiver - Pioneer Elite VSX-92TXH, Power Conditioner - Panamax M5300-EX, BluRay - Sony PS3, (2) ADCOM GFA 555 Bridged, Speakers - LSi 15, LSi C, LSi FX, Sub - 12" M&K VX-1250.

    Living Room:
    Schiit Saga, Parasound HCA-600, OPPO BDP-103D, LSi7
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  • fbm211
    fbm211 Posts: 1,488
    edited July 2009
    Not to jack this thread,, but WHERE IS BEN???...Anyone Know?Im a little worried as I havent seen any posts lately and thats not like him.
    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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  • hearingimpared
    hearingimpared Posts: 21,137
    edited July 2009
    fbm211 wrote: »
    Not to jack this thread,, but WHERE IS BEN???...Anyone Know?Im a little worried as I havent seen any posts lately and thats not like him.

    Ben is in Conneticut visiting his mom.
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  • ben62670
    ben62670 Posts: 15,969
    edited August 2009
    That amp has been modded quite a bit. You are going to need new jacks. I would just use some nice after market types.
    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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  • obieone
    obieone Posts: 5,077
    edited August 2009
    Welcome back.
    I refuse to argue with idiots, because people can't tell the DIFFERENCE!
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