The KA-9100 restoration.

Discussion in 'Kenwood-Trio/Kensonic-Accuphase' started by hopjohn, Aug 16, 2017.

  1. hopjohn

    hopjohn Kenwood Krazy Subscriber

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    Another sneak peek just arrived. If you are wondering if the decals are centered, he assured me they were. Perspective???

    [​IMG]

    It's an excellent multi-meter. I'm very happy to own it.

    A trait learned from the fairer sex.
     
    Last edited: Oct 12, 2017
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  2. rjsalvi

    rjsalvi Active Member

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    Coolness! Did you make the decals? Wait...lemme guess. You scanned the logo hi-res from Kenwood literature and then burned it to clear sticker paper? In any case, sweet.
     
  3. hopjohn

    hopjohn Kenwood Krazy Subscriber

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    I provided an original KA-7100 owners manual that had a decent sized logo on the back to the outfit that is doing the work. They work in vinyl and also do powdercoating. With that I decided to give the 9100 a little flair. What you're seeing in the last photo is the blanking plates stripped of paint and given a brushed finish and then the leaf logo decals applied. The idea was to compliment the look of the 9100's faceplate. Tomorrow they'll be clear coated so the finish and decal is preserved.
     
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  4. rjsalvi

    rjsalvi Active Member

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  5. 39cross

    39cross AK Subscriber Subscriber

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    Lot of work here, I hope you're pleased with the results - looks like another outstanding restore.

    Gotta say I'm worn out just from reading the details. Thanks for all great photos, I just re-read the triac piece trying to get those wires and their paths straight, it's starting to get clear(er).

    What's the story behind the heatsinks, I must have missed that part.
     
  6. hopjohn

    hopjohn Kenwood Krazy Subscriber

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    More photo updates from the powdwercoaters

    Front Top cover in a black/silver hammered powdercoat finish
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    Top back cover in a hammered black/silver powdercoat finish
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    Heatsinks in a gloss black powdercoat
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    Tranformers covers in a gloss black powdercoat with decals applied. This is prior to a clearcoat that will protect the decals from lifting.
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    Blanking plates pre-baked with clear powdercoat applied.
    [​IMG]
     
    Last edited: Oct 13, 2017
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  7. rjsalvi

    rjsalvi Active Member

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    HAWT!!! Can't wait to see it assembled! With what you'd done to the circuitry, it'll impersonate a modern high end unit.
     
  8. gort69

    gort69 AK Subscriber Subscriber

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    No kiddin'! Outstanding.
     
  9. hopjohn

    hopjohn Kenwood Krazy Subscriber

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    Alright here's a last bit of eye candy for today and the final update from the powdercoaters. It should provide a pretty good idea of what the assembled unit will look like. In the color and decal options I attempted to stay in keeping with the classic vintage look, but still add a bit of modern flair. I hope everyone likes it.
    [​IMG]

    [​IMG]
     
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  10. Hipocrates

    Hipocrates Anti-Muppet Subscriber

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    :eek2: Inspiring work man.
     
  11. rjsalvi

    rjsalvi Active Member

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    She's a looker. Do YOU like it? who cares what anyone else thinks. I think I know your new favorite amp. I think Gort69's 8150 is going to be a regular in his rotation as well. ;)
     
  12. hopjohn

    hopjohn Kenwood Krazy Subscriber

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    Well hopefully the subsequent posts made everything self explanatory. If you need any help with the triac just let me know.


    Thanks rjsalvi

    Well I have to give it to gort69 for planting the seed with the powdercoating work when he had his 9150 done. I was blown away by how good that looked. Initially I had no plans to do the covers, but as I was working on the unit I noticed just how easily the finish was coming off the heatsinks and it wasn't from getting bumped. It was literally just being rubbed off when scooted on my padded bench. So that was that, I decided it was going to get a full treatment. Also I'd always liked how Sansui and others had transformer covers emblazoned with their logo so that's where that idea came from. The plain blanking plates seem like something Kenwood left incomplete. Logic would have me believe they'd have done more with them had money crunching not been involved. Decorating them seems like a natural extension of an idea that likely existed, though obviously I have no evidence to back that up.

    Concerning my favorite amp I think that probably has to go to my Model 500, it's pretty darn special, but also a different animal from my other Kenwoods. For the later models the KR-9600 and KR-9100 are at the top of the list. Honorable mention must go to my restored KR-4200 which impresses me in ways I never thought it would.
     
  13. hopjohn

    hopjohn Kenwood Krazy Subscriber

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    When disassembling the parts for the powdercoaters I was in a bit of a rush. Having already made one trip with the covers and heatsinks, the artisan and I discussed some things that eventually led to me wanting to have transformer covers done as well. Eager to get the parts off and the second trip over with, I stupidly broke the already completed left amp board off at the screws while attempting to flip the amp over. Gutted.

    Having just had a discussion with gort69 about some unused grounding points with the 9100 amp boards I thought he may have a spare. And Wow, fortunately he did. This guy is a lifesaver, many thanks to him for saving my bacon. The board was quickly shipped out priority mail and rebuilt over the last two days in the exact same manner as the first. In fact, I moved most of the parts from the broken board to the new.

    When I attempted to reassemble the amp with the newly powdercoated parts it became quite obvious that nothing was going to fit correctly. This meant spending hours grinding away powdercoating on areas of the heatsinks where it was obstructing fit. After giving my Dremel tool a real workout the problems were rectified.

    After reassembling everything I needed to retest the amp on the DBT. The bulb went bright to dim as expected, but no relay click. Fudge! What now? After a few choice words I did a once over of the amp, nope perfect. Looking elsewhere, the power wire from the power supply to the control boards had snapped off. This was probably the sixth wire to have broken during the course of the restoration, but I was happy to have found it rather quickly. After a solid repair, another DBT test and the relay closed. We're golden.

    The multi-meter was put across the left terminals and boy was it way off, more than 800mv offset at the output. A quick adjust of the multi-turn trimmer and it was idling right at 0mv. A test at full power and some voltage checks and all looked good. The relay engages with real authority now. Done.

    The KA-9100 put up a bit of a fight, but persistence paid off. Some lessons were learned along the way that should make any subsequent 9100 rebuilds easier.

    [​IMG]

    [​IMG]

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  14. SicMan

    SicMan Fire up those speakers Subscriber

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    Great job and great thread. :beerchug: :thumbsup:
    Looks super John, I like it. Now to break it in for a while.
     
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  15. gort69

    gort69 AK Subscriber Subscriber

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    Really outstanding thread and restoration John, and I LOVE the look. Your attention to detail and the documentation of it is all top-notch. Your powder coat guy gets a blue ribbon as well - I know you went into that deal with your fingers crossed.

    The Kenwood decals on the transformers and screw cover plates are a very nice touch. I thought for certain you were going a different route with that, such a this

    xbxcbxb.jpg

    VA4C2Rn.jpg

    Kidding of course - and thanks for the kind words.

    PS - this might explain why the initial DC offset was so far off on that left amp board, and probably why a couple of transistors and resistors had been replaced. This is the module I removed from that channel which I'd forgotten about. (it worked!)

    P6291057.JPG
     
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  16. dlucy

    dlucy dlucy67 (Doug) Subscriber

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    I've found quite a few wires snapped off, mainly at the crease points in their first wire-wrapping turn. With bending the boards back and forth so much (disassembly, testing, reassembly) this seems to happen a lot. I wouldn't interrupt the thread here except for:

    I've found three hard-to-detect wire breaks that other might want to check. The three-conductor leads from the rear panel RCA jacks all have a bare silver conductor that connects to the ground rail between the RCA jacks. of the eight sets of three-conductor cables, three of mine were broken, loose and just hanging there in space... but they were still hanging in space right next to the place where they broke, so it took very specific inspection to find the breaks.
     
  17. rjsalvi

    rjsalvi Active Member

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  18. hopjohn

    hopjohn Kenwood Krazy Subscriber

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    Yes, definitely time to have a listen and enjoy it.

    Powered by Powerade hahaha, perfect. :rflmao:

    Ahh okay. I didn't expect it to be real close, but was a little surprised it was that high. I was just glad to be monitoring it right at the get go, tool in hand. Thanks for the replacement board, it worked great.
     
  19. hopjohn

    hopjohn Kenwood Krazy Subscriber

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    I actually checked those before putting the rear shield back on, but it's a good thing to point out for future reference.

    :thumbsup::thumbsup:
     
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  20. SicMan

    SicMan Fire up those speakers Subscriber

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    Now the real question is "what will you charge some one to do this" LOL ...
    Just curious. :dunno:

    burning_amp.jpg
     

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