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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    It's time to begin another big project. Up now a Kenwood KA-9100. The top of the line integrated for 1977. This particular amp was provided by fellow AKer and committed bronzed-face Kenwood collector, gort69. Sixty-nine? is that his favorite year or favorite something else, who knows, but he parted ways with this all-stock, silver faced beauty for undisclosed fortunes. Now, after a trip to the lone-star state, it's in my loving hands and time to restore it.

    Get your popcorn ready Kenwood lovers.
     
  2. gort69

    gort69 AK Subscriber Subscriber

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    This

    33881_154027691297018_100000693631228_307386_4375006_n.jpg
     
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  3. hopjohn

    hopjohn Kenwood Krazy Subscriber

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    A 1969 Camaro Convertible. The man has impeccable taste.
     
  4. hopjohn

    hopjohn Kenwood Krazy Subscriber

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    In all seriousness, thanks again to gort69 for selling me the amplifier. It's been a glaring hole in my collection for several years now and he gave me a very fair deal on it so many props to him for allowing this to happen.

    Let's start by discussing the disassembly and serviceability. The 9100 seems to have a reputation, by multiple accounts on these forums, to be a rather difficult amplifier to work on. I would tend to agree even though I was expecting something frighteningly worse The front boards require you remove an alarming number of screws to access. The sub-frame that houses the meters, two control boards, right side switches and volume pot have to be completely removed for recapping and adequate switch cleaning to take place.

    EDIT: Here's a photo showing just how much hardware is holding it all to the front sub-frame. There are more screws that can't be seen on the interior top edge and of course on the sides that meet the heatsinks.
    [​IMG]
     
    Last edited: Aug 16, 2017
  5. fernarias

    fernarias AK Subscriber Subscriber

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    The preamp is the hardest part to disassemble and to reassemble. My tip is to separate the metal bracket, after you have removed the screws, from the left and then work to the right. Do the opposite when installing. There's also a fragile black wire that connects the two control units (that's what they're called in the manual but they contain the eq switches and knobs). I would note the position of that wire and desolder it on one side until your done.

    I had to go into the preamp three times, first time during the recap, the second time to fix the black wire and the third time when I opened all the switches and cleaned them (solved intermittent problems that spraying deoxit just didn't solve). It's a great amp.
     
  6. gort69

    gort69 AK Subscriber Subscriber

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    You're welcome John, and thank you for the purchase - saved me the ebay headache....plus I figured you were frustrated thrashing on pipsqueak amps and need something to sink your teeth into. Looking forward to the thread.

    You too, huh? I had to send an emergency PM to a member who had just buttoned one up. It broke off so cleanly I had no clue. He assured me his had broken off as well so I didn't feel so bad. I replaced the wire with a longer piece of stranded.
     
  7. hopjohn

    hopjohn Kenwood Krazy Subscriber

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    My black ground wire broke off during disassembly as well. Fortunately, I was given fair warning so it'll be replaced before all goes back together.

    Here's the little bugger on Pin 12 of the "rear" control board.
    [​IMG]
     
  8. gort69

    gort69 AK Subscriber Subscriber

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    Hmmmm - that's not the wire I was talking about. It's this one - connects to pin #8 on the rear board and J6 on the front board.

    P1011153.jpg

    P1011154.jpg
     
  9. hopjohn

    hopjohn Kenwood Krazy Subscriber

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    Ahh ok, good to know. I think that one is still attached for now. I'll keep a close eye on it.
     
  10. hopjohn

    hopjohn Kenwood Krazy Subscriber

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    If I'd read more closely I'd have known what you meant, my apologies. Probably not a bad idea just to replace that one with some stranded as gort69 pointed out.
     
  11. hopjohn

    hopjohn Kenwood Krazy Subscriber

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    Another rather difficult part of restoring a 9100 is the work required on the two diode boards. These boards contain the main rectifiers and portions of the protection circuit. They are mounted in place with the four primary filter caps. In order to reach the component side of these two boards the filter caps need to be unsoldered from them. The large surface area of the pads and foil pattern makes using a smaller iron quite the task. I keep a 63 Watt Hakko 456 soldering iron around for chassis work and jobs such as these. With the use of the 456 and some solder wick, quick work can be made of removing the caps.

    Foil side of the diode boards with one of the four caps desoldered.
    [​IMG]
     
    Last edited: Aug 16, 2017
  12. DrumminDaddy

    DrumminDaddy Hit it, Baby !! Subscriber

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  13. fernarias

    fernarias AK Subscriber Subscriber

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    It's always better with pictures. I'm glad gort69 had pictures. I replaced mine with hook up wire.
     
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  14. fernarias

    fernarias AK Subscriber Subscriber

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    Yup, but I didn't catch it until after I started testing. I took forever since I thought that maybe I inverted a cap.
     
  15. rjsalvi

    rjsalvi Active Member

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    I can't believe he sold one! Where is the real gort69??? ...what have you done with him??? :biggrin:
     
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  16. SicMan

    SicMan Fire up those speakers Subscriber

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    He's breaking. Really he has too much stuff. LOL

    John
     
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  17. hopjohn

    hopjohn Kenwood Krazy Subscriber

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    The KA-9100 uses a couple of my least favorite style switches with the Meter Range and Loudness control. The conventional Deoxit cleaning approach on these guys typically doesn't do much but make a greasy mess. It really comes down to the lack of good access to the contacts. Since I really don't want to have to dig back into the front panel I felt like it was best to do a disassembly of them.

    [​IMG]

    [​IMG]
    [​IMG]
     
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  18. fernarias

    fernarias AK Subscriber Subscriber

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    I disassemble mine also but I also discovered to use either deoxit gold or fader to protect the silver contacts.
     
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  19. SicMan

    SicMan Fire up those speakers Subscriber

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    They get pretty bad, the separate switch on the back is mad the same same way. It;s a little easier
    to open or clean.
     
  20. hopjohn

    hopjohn Kenwood Krazy Subscriber

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    Those angry switches are the worst! :D

    Yes sir, I like me some Deoxit Gold for preservation. I just had the tiny tube of it and ran out, more is on the way. I used Fader Lube for now. I also like Super Lube for the mechanical portions.
     

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