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Thread: Marantz pm4 capacitors replacement

  1. #1
    Join Date: May 2016

    Location: Milton Keynes

    Posts: 1,532
    I'm Andrew.

    Default Marantz pm4 capacitors replacement

    Help ....please
    Ok so Iím going to dive in BUT !!
    I canít identify the smaller blue caps and those bigger black ones are no longer available.
    I have researched all the posts on other sites but theyíre years old and Iíve had no reply from the person posting the thread.
    Itís imperative that I donít lose the magic .
    Iím no expert at this but it doesnít scare me either.
    I will replace each component one at a time and listen in between each stage .
    At some point someone has replaced the horrible original speaker terminals so Iím now wondering if this has been recapped (all the caps are bright and shiny )there is an orange gunk around the base of the caps which could have been left from the original caps ? Or is this wishful thinking


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  2. #2
    Join Date: Sep 2012

    Location: Derbyshire

    Posts: 310
    I'm mark.

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    Looks like its been done already to my untrained eyes.

    If its working and sounds OK I'd be very tempted to leave it alone...

  3. #3
    Join Date: May 2016

    Location: Milton Keynes

    Posts: 1,532
    I'm Andrew.

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    Quote Originally Posted by DiveDeepDog View Post
    Looks like its been done already to my untrained eyes.

    If its working and sounds OK I'd be very tempted to leave it alone...
    Thatís what I thought also Iíve now looked at the underside of the circuit board and the soldering is different around the larger black caps .
    Itís going back together now


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  4. #4
    Join Date: Apr 2012

    Location: Southall, West London

    Posts: 36,847
    I'm Geoff.

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    I never re-cap anything unless it's ridiculously old or there's a suspect looking cap.

  5. #5
    Join Date: May 2016

    Location: Milton Keynes

    Posts: 1,532
    I'm Andrew.

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    Quote Originally Posted by walpurgis View Post
    I never re-cap anything unless it's ridiculously old or there's a suspect looking cap.
    Music to my ears


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  6. #6
    Join Date: Oct 2016

    Location: Bolton, England

    Posts: 1,381
    I'm Andrew.

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    What's access to the underside of the board like? If it's a pain in the backside I'd be tempted to leave it alone as much as possible. The flying leads are attached by "wire wrap", which was common with Japanese equipment of that era. It's actually a very good way to make a joint but impossible to remove and then re-wrap.
    The usual "re-cap" involves replacing just the main power supply reservoir capacitors. If you want to go further you could replace all the electrolytics, though there are probably dozens of them.
    I'm not sure about the orange gunk. Yes, it could be residue from the original caps which have since been replaced.

  7. #7
    Join Date: May 2016

    Location: Milton Keynes

    Posts: 1,532
    I'm Andrew.

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    Quote Originally Posted by RothwellAudio View Post
    What's access to the underside of the board like? If it's a pain in the backside I'd be tempted to leave it alone as much as possible. The flying leads are attached by "wire wrap", which was common with Japanese equipment of that era. It's actually a very good way to make a joint but impossible to remove and then re-wrap.
    The usual "re-cap" involves replacing just the main power supply reservoir capacitors. If you want to go further you could replace all the electrolytics, though there are probably dozens of them.
    I'm not sure about the orange gunk. Yes, it could be residue from the original caps which have since been replaced.
    Itís all back together now and singing away , thanks for your input Andrew .


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  8. #8
    Join Date: Aug 2008

    Location: Suffolk, UK

    Posts: 1,308
    I'm Paul.

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    I think the brown stuff is just the standard glue that the factory would have used to glue in the capacitors after soldering. This is normally done just to stop them moving. If you think you need to do this to the new replacement caps you can use a small tube of cheap silicone, putting 3 small blobs around the bottom. I doubt that it is really necessary.

    Assuming that the replacement capacitors have the same voltage and capacitance ratings as the originals the only potential concern would be the ripple current ratings of the large PSU caps. Ripple currents might be relatively high when the amp runs in class A. The the caps don't have a high enough rating they could fail prematurely. I suspect you are OK as the amp is not really a powerhouse beast.
    ~Paul~

  9. #9
    Join Date: May 2016

    Location: Milton Keynes

    Posts: 1,532
    I'm Andrew.

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    Quote Originally Posted by Primalsea View Post
    I think the brown stuff is just the standard glue that the factory would have used to glue in the capacitors after soldering. This is normally done just to stop them moving. If you think you need to do this to the new replacement caps you can use a small tube of cheap silicone, putting 3 small blobs around the bottom. I doubt that it is really necessary.

    Assuming that the replacement capacitors have the same voltage and capacitance ratings as the originals the only potential concern would be the ripple current ratings of the large PSU caps. Ripple currents might be relatively high when the amp runs in class A. The the caps don't have a high enough rating they could fail prematurely. I suspect you are OK as the amp is not really a powerhouse beast.
    Hi Paul, itís all back together now .

    Cheers


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  10. #10
    Join Date: Oct 2017

    Location: West Wales

    Posts: 55
    I'm Alan.

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    Nice amp by the way, very sweet sound and I like the different style.

    The black 6800uf caps are Panasonic TS-UP series. Sadly no longer in production, but excellent quality. As long as they are the 63v ones, the ripple is 4.6 amps at 100Hz, so fine. Pity they are not the 105 degree C ones though...

    As said previously someone has recapped it and haven't bothered to clean the glue from the PWB too well. Cosmetics.

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