Pioneer M-22 Power Amp - Epic Japanese Gear From the Past

Discussion in 'Power Amps' started by Armaegis, Mar 30, 2017.

  1. dBel84

    dBel84 Friend

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  2. Armaegis

    Armaegis Friend

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  3. Vishal

    Vishal New

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    I've been following this thread for a while now, it's helped me refurbish my pioneer M22.

    Thought I'd show you some of the things I've been up to with my own rebuild of this wonderful amplifier.

    My power capacitors have seen better days and to find replacements is expensive and not the same fitment.

    I decided to build my own keeping to the original size and aesthetics of the amplifier.

    I know it's a crazy idea but I had to try something different, so i cut away the old mount from the capacitor, bought some Murndorf 40v 33000uf caps, 3D printed some holders from PETG and used a perspex tube to house it all keeping to the original size.

    I think it came out well and now i just have to install them!



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  4. Armaegis

    Armaegis Friend

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    @Vishal
    And you're running some smaller caps in parallel with the Mundorfs?
     
  5. Vishal

    Vishal New

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    [​IMG]

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  6. Vishal

    Vishal New

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    Bypass coupling capacitor, just a PIO 0.1uf.
     
  7. uncola

    uncola Friend

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    the tops look like little speaker cones.. on purpose? either way, nice job fabricating those
     
  8. Vishal

    Vishal New

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    Yes that was my intention, just wanted to give it a theme and futuristic look. It also serves a purpose to hold the capacitor I place and keep it in position.
     
  9. donnie00darko

    donnie00darko New

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    New to forum. What a wonderful thread to read. I was wondering if you all leave the m22 on all the time and if its okay to do so. Do you turn off the amp at the end of the day? Curious to know your thoughts on what would be the correct way to do it. Leave on? Or cycle on and off.

    Thanks
    Don
     
  10. skem

    skem Friend

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    I turn it off. It produces way too much heat to leave on...and it’s just baking those capacitors and shortening their life. But once I left it on by mistake and, subjectively, I felt it sounded better than normal having been on for hours. Wouldn’t change my behavior though.
     
  11. Vishal

    Vishal New

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    Guys just my luck, so the amp was fired up this evening everything is as it should be, the only issue I have is that the output relays aren't engaging aaarrrgghhh.

    I used these as replacements

    Omran My2n

    https://www.mouser.com/ProductDetai...Ee0xWmeNOnTfsn9b1n4pFBQVQzQifh1RoCzHYQAvD_BwE

    They seemed to be a smililar spec but they don't seem to engage.

    Should i try and source these ones?

    https://www.digikey.co.uk/product-d...div/G4W-1112P-US-TV8-HP-DC24/Z5210-ND/1815530

    Thanks almost there just can't see why the ones installed aren't engaging, any other recommendations for replacements relays?
     
  12. Vishal

    Vishal New

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    Thanks for the help guys! Sarcasm, ordered new relays which did the trick and she's purring away without any issues.

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  13. Vishal

    Vishal New

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    decades of dirt

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    nice and clean now

    B4F93307-FBEE-4786-8730-F16ABEA470FB.jpeg

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    new rca connectors fit a treat also replacing the speaker binding posts with audio note items

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    next is respraying and touching up the metal work and heat sinks where there are scratches.

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    [Mod edit to a photo]
     
    Last edited by a moderator: Jun 7, 2020
  14. Armaegis

    Armaegis Friend

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    Ah it does my heart joy to see metal being cleaned... but I hope you're spraying with a thermally conductive paint?
     
  15. Vishal

    Vishal New

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    Just touching up scratches where you see metal, not doing a complete respray so it's not really needed.
     
  16. Vishal

    Vishal New

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    You know what the heat sinks and metal work just needed so much work I just went all out and resprayed the whole thing.

    Anything black was resprayed, high temp plastikote paint was used in matt black. Two coats of primer, 3-4 coats of final.

    You have to just take your time preparation is key and lightly go at it, every coat check you work and sort out any issues in the layers of paint.

    masked chassis and spraying bottom base

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    absolutely anything audio goes through this capacitor, the choice was to use good quality one. this meant making it fit.

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    Looks like new

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  17. Armaegis

    Armaegis Friend

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    Dude, at this point you've raised my expectations and I'll be disappointed if you don't ditch the 3d printed holders and mill out your own brass or acrylic fittings...
     
  18. skem

    skem Friend

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    What did you use for the differential pair, the five pin transistor. Based on the pin out I’d guess KSS992s

    would love to hear that coupling cap.
     
  19. Vishal

    Vishal New

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    hahaha because 3d printed holders wasn't good enough already? Access to a cnc lathe/milling machine is limited presently. Maybe in the future, at least the 3d printed version gives many more diy audio people the ability to make and design their own., plus there prototypes and I can make the print of a higher quality or different design. For now they are doing a grand job!
     
    Last edited: Jun 7, 2020
  20. Vishal

    Vishal New

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    https://imgur.com/a/qILrnu6

    Had to match the hfe closely then make sure they were thermally bonded to each other.

    A992 transistor.
     
    Last edited: Jun 8, 2020

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