4 caps..input board...adcom gfa555

sda2mike
sda2mike Posts: 3,131
edited November 2011 in The Clubhouse
good morning!

putting together an order for soniccaps..the input board on my adcom gfa555 has 4 caps that i want to replace..not much info is printed on them...i have an owners manual that list caps with different 'c' numbers, than what is stamped on the board...the one's i want to replace are: C 608 & 607, C 609 & 610...the amp was made in 86...it has the input board configured vertically..would a service manual solve this?

thanks
mike
Post edited by sda2mike on
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  • [Deleted User]
    [Deleted User] Posts: 7,658
    edited November 2011
    Hi Mike,
    Usually the service manual will have a parts list that should give you capacitance and working voltage for every cap. If you are certain that there is no DC leakage from your preamp you could consider removing the input coupling caps on the power amp. There's nothing that sounds as good as a piece of wire. If you're unsure about the preamp then the caps are necessary.
    Regards, Ken
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  • sda2mike
    sda2mike Posts: 3,131
    edited November 2011
    actually, i have the service manual...didn't realize it till i went on hifi engine..hopefully someone will know which caps to order..for c608 & 607 the schematic shows 100 v 47 and 50 v 4.7...
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  • [Deleted User]
    [Deleted User] Posts: 7,658
    edited November 2011
    I believe the first number is the working voltage and the second is the capacitance. It would be 47uF, 100V and 4.7uF, 50V.
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  • PreCd
    PreCd Posts: 786
    edited November 2011
    sda2mike wrote: »
    actually, i have the service manual...didn't realize it till i went on hifi engine..hopefully someone will know which caps to order..for c608 & 607 the schematic shows 100 v 47 and 50 v 4.7...

    Mike I just recapped my GFA-555 and the 4 capacitors are:

    2 each 100v 47uf Dimensions LxW 15x10mm
    2 each 50v 4.7uf Dimensions LxW 10x5mm

    I used Panasonic FCs. Just finished the GFP-565 this week....all with Elna Silmic IIs.

    Enjoy.

    Kevin
    SDA2BTL
    Marantz CD5004
    Adcom GFA-545
    Bottlehead Quickie Tube Preamp
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  • sda2mike
    sda2mike Posts: 3,131
    edited November 2011
    there we go! thanks Kevin!
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  • sda2mike
    sda2mike Posts: 3,131
    edited November 2011
    hmmm...i think i understand the schematics now...everything is 'per channel'..
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  • PreCd
    PreCd Posts: 786
    edited November 2011
    sda2mike wrote: »
    hmmm...i think i understand the schematics now...everything is 'per channel'..

    That is right.

    I had a hard time finding my schematic as there are more than one for these 555s. Here is the schematic for mine:

    My 555 schematic
    SDA2BTL
    Marantz CD5004
    Adcom GFA-545
    Bottlehead Quickie Tube Preamp
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  • heiney9
    heiney9 Posts: 25,165
    edited November 2011
    I would recommend Panasonic FC's as well. Sonicaps are overkill in that position and don't come in the proper values or sizes and you don't need to use a film cap there, electolytic is just fine. Sorry I never responded to your PM, but scour www.diyaudio.com for all kinds of info as this was/is a popular amp that has a load of repair/upgrade threads over the years.

    If FTGV see's this thread he has knowledge way beyond mine as far as circuits go, maybe he can help or give some advice.

    Why are you replacing them? For piece of mind or are they damaged? If you are doing it for piece of mind you should do them all. FTR, only a certain run of 585's and 565's have the leaking cap issue if that's what you are trying to avoid. 555's in general didn't have the defective caps in them.

    H9

    P.s you also need a Radial lead cap not axial like the Sonicaps and be sure they aren't polarized or you need to look for that as well. Panasonic FC is an excellent choice but also be sure the dimensions fit.
    "Appreciation of audio is a completely subjective human experience. Measurements can provide a measure of insight, but are no substitute for human judgment. Why are we looking to reduce a subjective experience to objective criteria anyway? The subtleties of music and audio reproduction are for those who appreciate it. Differentiation by numbers is for those who do not".--Nelson Pass Pass Labs XA25 | EE Avant Pre | EE Mini Max Supreme DAC | MIT Shotgun S1 | Pangea AC14SE MKII | Legend L600 | BlueSound Node 3 - Tubes add soul!
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  • heiney9
    heiney9 Posts: 25,165
    edited November 2011
    One last thing with Adcom is a lot of the parts they used have their own part number so it can be more difficult to determine values.

    H9
    "Appreciation of audio is a completely subjective human experience. Measurements can provide a measure of insight, but are no substitute for human judgment. Why are we looking to reduce a subjective experience to objective criteria anyway? The subtleties of music and audio reproduction are for those who appreciate it. Differentiation by numbers is for those who do not".--Nelson Pass Pass Labs XA25 | EE Avant Pre | EE Mini Max Supreme DAC | MIT Shotgun S1 | Pangea AC14SE MKII | Legend L600 | BlueSound Node 3 - Tubes add soul!
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  • sda2mike
    sda2mike Posts: 3,131
    edited November 2011
    thanks brock and kevin! this is only to prevent disastrous leaking of the caps onto the board..i'm not concerned with the big power supply caps...this amp runs great..i just want to keep it that way...especially when it comes time to put it on the market..thinking about tubes in my amp:) i'll check the link brock, thanks..
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  • heiney9
    heiney9 Posts: 25,165
    edited November 2011
    Like I said the 555 had NO ISSUES with leaking caps, it was only the 585 and 565 mono's and not all of those had issues just a certain run of them. Knock yourself out if you still want to replace them, but they were never part of the defective caps.

    H9
    "Appreciation of audio is a completely subjective human experience. Measurements can provide a measure of insight, but are no substitute for human judgment. Why are we looking to reduce a subjective experience to objective criteria anyway? The subtleties of music and audio reproduction are for those who appreciate it. Differentiation by numbers is for those who do not".--Nelson Pass Pass Labs XA25 | EE Avant Pre | EE Mini Max Supreme DAC | MIT Shotgun S1 | Pangea AC14SE MKII | Legend L600 | BlueSound Node 3 - Tubes add soul!
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  • FTGV
    FTGV Posts: 3,649
    edited November 2011
    Due to age it is not a bad idea to replace the electrolytics.They are not in the direct signal path and any good lytic (like the FC's) will suffice.
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  • sda2mike
    sda2mike Posts: 3,131
    edited November 2011
    understood...i figured they were reffering to the big caps...i'd rather not delve into it, if it's just overkill..i have some old marantz imperial 6 spkrs, now they definately have a leaky cap!

    thanks again!
    mike
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