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Kenwood ka-9100 help

Discussion in 'Kenwood-Trio/Kensonic-Accuphase' started by rossm, Feb 17, 2018.

  1. rossm

    rossm AK Subscriber Subscriber

    Messages:
    273
    Good news, both channels on the parts amp are working, along with the preamp and tone controls. About the only electrical fault is the relay ckt.
    It does have some physical damage on the back, some of the speaker terminals are damaged and some rca jacks are damaged

    A9E4FB4A-010F-4CEC-B1C5-2F0265013E9C.jpeg
    756BBC8E-E3D2-4FAA-B7DD-A4C95B174E6F.jpeg

    Just like my original 9100 The power switch was bent 90 degrees over
    9FE459CC-0C5F-436A-B4ED-6EB9EE1EFE79.jpeg

    I broke the original amps switch trying to straighten it, so I got creative and used some locking forceps and soldering iron to heat up the shaft and then carefully bend the switch back to its normal position
    161784FF-0097-4699-B3FA-96108823DD83.jpeg

    And it worked !!!
     
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  2. rossm

    rossm AK Subscriber Subscriber

    Messages:
    273
    Hi again,
    Replaced the zener diode and still had 46 volts on cathode side of D1. But I did figure out why, with the amp board disconnected from the case ( on the bench I had connected pins 5 & 11 +- B voltage and 9 which is ground to the power supply) I didn't think to connect the other ground pin 3 to the case. That brought my cathode side of D1 down to 24 v, but still +34v on pin 3 of the ta-100w. Did some more voltage checks and it looks like pins 1&7 of the ICe1 uPA63H are off, 24v pin 1, 17v pin7, they both should be 20.5v, maybe ce6 is passing DC ? Might pull it tomorrow and see. Also pins 3 and 5 of ICe1 should be .8v and I have 2.8v. Notice the typo , the left power amp is all odd numbers, yet we have Re38 and C6 ! looked all over before I figured out its Re37 and C5.

    ka9100.png
     
  3. rickl

    rickl Active Member

    Messages:
    109
    Location:
    Twin Cities
    i would measure the collector of Qe7 on the working amp and compare with your board. looks like it should be 1.15v and not 34v you are measuring. Pin 3 on the ICe3 might be easier to get to.

    did you replace Ce13/Ce15? those voltages look off too. Plus you are measuring 49v on a 16v cap. Yikes. Makes me wonder if ICe3 is working to get 49 v on pin 4.
     
  4. gort69

    gort69 AK Subscriber Subscriber

    Messages:
    1,095
    Location:
    Vancouver, WA
    Good to hear JG - makes you wonder how many 9100s have been scrapped thinking a TA-100w was bad when it was something else....
     
    tarior likes this.
  5. rossm

    rossm AK Subscriber Subscriber

    Messages:
    273
    Hi finally had some time today
    I removed the small ceramic caps and the voltage is about the same
    The collector of Qe7 is 35v also have 32v pin 7 of Ice3
    Ice1 2.7 v on pins 3 & 5 should be .8 v think Ice1 is bad ?
     
  6. rossm

    rossm AK Subscriber Subscriber

    Messages:
    273
    C44DBAA4-C5D9-48EA-BE72-9BF5BB8E907F.jpeg Hi again
    Was able to score a parts ka-9100, both channels appear to function but relay does not engage.
    Removed the amp board and recapped it.
    C44DBAA4-C5D9-48EA-BE72-9BF5BB8E907F.jpeg
    Will replace q9 when the next mouser order gets here
    Also got a new tool, Hakko de soldering tool.
    3C1F43B9-A99E-46F5-AD63-745BD18EBFEC.jpeg
    Really like it, made short work of the 4 big caps

    734C0D3D-238B-419F-99A2-B94A002AC900.jpeg

    Will be replacing the 12000 uf 63 v with the reccomended 10000uf 63 v solder tab caps, would have preferred the 15000uf but twice the money, has anyone done that ?
    After 24 hours 3 of the big caps still had 45v while one had 12v. Looks like one of the caps is having an issue
    016F90CB-7267-4008-833F-132E83F5A79E.jpeg
     

     

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  7. rossm

    rossm AK Subscriber Subscriber

    Messages:
    273
    Hi
    Do you have a link for the part ?
    Thanks
     
  8. rossm

    rossm AK Subscriber Subscriber

    Messages:
    273
    HI
    I am back on the 9100 again. I have recapped and replaced all transistors on both of the power amps. I have also replaced the trimpot with a multi turn unit. But it looks like I may have introduced a problem. The amp powers up and plays fine (sounds great) but I am unable to adjust the off set voltage. I can get the voltage to about .004 volts but its swinging around like crazy +- .070 volts. Both amps are doing this, but the left channel is worse, also its getting pretty warm. I have checked voltages on the transistors and they are about what I would expect, with the exception of Q11 collector voltage (also tied to pin 9 of tw100) its swinging around quite a bit as well -1.2 v +- .7 volts. I had replaced Q11 with C2690A-Y. Thinking about putting old Q11 transistor back in, but its a pretty warm day in the lab... Any suggestions ?
    thanks
     
  9. gort69

    gort69 AK Subscriber Subscriber

    Messages:
    1,095
    Location:
    Vancouver, WA
    Which subs did you install at Qe1-4?
     
  10. rjsalvi

    rjsalvi Well-Known Member

    Messages:
    563
    Location:
    San Diego, CA
    Main filter cap link: https://www.mouser.com/ProductDetail/Nichicon/LKG1J153MKN?qs=sGAEpiMZZMtZ1n0r9vR22SV4CH/%2butB%2b9QcVT5Iv%2bWCGsekoD045KQ==

    Other main filter cap link (requires minor dremeling of filter cap mounting slots): https://www.mouser.com/ProductDetail/KEMET/ALT22A153DE063?qs=sGAEpiMZZMtZ1n0r9vR22fqp084l1X3er8GMABHdfi0=

    Are the voltages on amp board test point pins 5 & 6 (+57Vdc), 11 & 12 (-57Vdc) solid, or jumping around? The collector of Q11 is tied to pin 7 of the TA-100, not pin 9. Pin 9 is a ground.
     
  11. rossm

    rossm AK Subscriber Subscriber

    Messages:
    273
    Hi Gort, Just got back from vacation, sorry for the late reply
    Q1 & Q3 are C2690A-Y
    Q5 & Q7 are A1220A-Y
    Q9 C1845
    Q11 C2690A-Y
    thanks
     

     

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  12. rossm

    rossm AK Subscriber Subscriber

    Messages:
    273
    HI
    Thanks for the links
    The +- voltages look good, I have a donor amp board (non modified) that seems to work fine. Your right, don't know what I was thinking Q11 is tied to pin 9.
     
  13. gort69

    gort69 AK Subscriber Subscriber

    Messages:
    1,095
    Location:
    Vancouver, WA
    You sure on that? If so, I'd replace them with KSC1845
     
  14. rossm

    rossm AK Subscriber Subscriber

    Messages:
    273
    Thanks I will check. What’s really odd is if I select the back switch to separate the amp and preamp the offset voltage becomes rock solid. I can connect my MP3 player to the power in and it plays fine.
     
  15. Kenny*G

    Kenny*G AK Subscriber Subscriber

    Messages:
    66
    Location:
    Dickinson, Texas
    Not meaning to bust in your thread but I just tried connecting my tablet to my ka-9100 like you mention and I have relatively clean sound, but the volume control & balance don't work. With the switch in Normal, I barely get sound on the right channel with a lot of static & popping. So does this give me a starting point of where to start looking for an issue ?

    Again, Sorry for bust in your thread.
     
  16. rossm

    rossm AK Subscriber Subscriber

    Messages:
    273
    Hi
    Sounds like your might have some dirty pots or switch’s, a good deoxit job should clear it up, search this site on how to clean the ka-9100 switches, they can be hard to clean. You might want to start a new post to get more exposure, lots of folks willing to help here
    Good luck
     

     

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  17. gort69

    gort69 AK Subscriber Subscriber

    Messages:
    1,095
    Location:
    Vancouver, WA
    That's because the volume and balance (and all other controls) are in the pre-amp section. "Power in" is only the power amp, so make sure whatever you connect there has a volume control or else your speakers and ears will take all the power the amp can deliver.
     
  18. rossm

    rossm AK Subscriber Subscriber

    Messages:
    273
    HI Gort69
    Thanks I don't know why I put the C2690's in, I had ordered the KSC1845. I replaced them tonight and It looks like the amp temps is lower now, I was seeing 130 deg on the TA 100 and now its down to 100 deg. But I am seeing 200 mv voltage swings on the speaker outputs with the volume at 0. Switching the amp to separate amp/preamp the voltage is rock solid. I connected a scope to the preamp outs and didn't find any strange high freq signals. Every thing seems to function otherwise tone, volume, loudness etc and it sounds great.
    thanks again..
     
  19. SicMan

    SicMan Fire up those speakers Subscriber

    Messages:
    2,973
    Location:
    Wolcott - CT. USA
    One thing to check is see if there is AC riding on the +/-57 Volts (High Ripple)
    AND check R23 for open.
    OR the 24volt zener.
     
    Last edited: Jul 30, 2018
  20. rossm

    rossm AK Subscriber Subscriber

    Messages:
    273
    Just wanted to post that I finally got one of the KA-9100’s finished and working great
    EADF10A4-DD69-4A6B-8C5F-6773C37711D0.jpeg

    Still trying to sort though the 2nd 9100. Did complete recap and get popping sounds out of the speaker when turning off, also having wild voltage fluctuations when adjusting the DC Offset, voltage problems go away when preamp is disconnected though.
     
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