TA-100W follow-up "work around"

Discussion in 'Kenwood-Trio/Kensonic-Accuphase' started by norm kerr, Feb 25, 2011.

  1. EchoWars

    EchoWars Hiding in Honduras

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    The fact that a 2SB718 is a totally different transistor than a 2SD718.
     
  2. srinath

    srinath Super Member

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    Yeow - thanks.
    Cool.
    Srinath.
     
  3. srinath

    srinath Super Member

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    2,455
    OK got it, I think this amp may have a solder bridge or a wire to wire short that caused it to die in the previous incident ... I will look it over with a very fine tooth comb.

    Cool.
    Srinath.
     
  4. robo81

    robo81 New Member

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    Hi
    I have never posted here before.
    I have Kenwood ka 9100 with blown ta100w.

    Searched everywere and all I saw was how to modify
    sanken.
    But found my orginal kenwood Ta100w on aliexpress
    been installed and worked perfectly
     
  5. robo81

    robo81 New Member

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    Hope this helpes for those in similar circumstances
     
  6. jrj90620

    jrj90620 New Member

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    Which Aliexpress Seller?

    I bought a TA-100WA from an Aliexpress seller and it was defective.Returned it and never got a refund or replacement.Can you tell me who you bought yours from.
     
  7. SicMan

    SicMan Fire up those speakers Subscriber

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    Oh Boy !!! :scratch2:
    I bought 2 of them and will be testing them this week .. that is sad that they sell that stuff .. took 40 days to get it and they did not honor their 30 day policy of returning purchase price either .. :thumbsdn:

    John M
     
  8. SicMan

    SicMan Fire up those speakers Subscriber

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    WELL .. JUST A FOLLOW UP.. i WAS ABLE TO TEST THE 2 ta100'S i BOUGHTand they both work .. I guess I was lucky .. you could see they are pulls from units by the condition of the leads ..

    I still wouldn't recommend to buy from them... :no:

    AS far as the Sanken parts I'll be working on a prototype with the STD03's and the emitter resistors etc over the holidays (if I get to it) ..
    Cheers Peeps!!! and Merry Christmas .. :beerchug:

    John M
     
  9. EchoWars

    EchoWars Hiding in Honduras

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    The stock 'protection' in the original TA-100W module was simply a current foldback scheme (V/I limiter). They work OK when an amp is overdriven, but have little use when the output is shorted or some such. While I'd prefer a solution that includes such circuitry, I'd not lose a lot of sleep over it's loss. The 9100 still has DC protection through the relay circuitry.
     
  10. SicMan

    SicMan Fire up those speakers Subscriber

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    Thanks Glenn .. I'm concerned about the speaker wire short when it's playing .. not going to stop this just for the protect concerns, I'm looking to test the stability of this fix and go from there .. I have a few ideas but haven't really put them on paper yet .. too much multitasking .. need to focus.. right ... The SAP16's work fine .. but don't short them out while playing .. the ones I have out there are still working. I guess they are sticking to my "DO NOT Short the speaker wires out! "

    see ya
    John M
     
  11. restorer-john

    restorer-john Super Member

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    I have had some supposed 'pulls from old gear' and they were fakes that had been tinned roughly to 'look' like pulls. When you have a full length straight lead with solder on it, be suspicious. Order one extra of everything and cut it open first.
    I get my stuff direct from a very reliable, 100% trustworthy source in Japan now. Nowhere else for semis.

     
  12. SicMan

    SicMan Fire up those speakers Subscriber

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    Good (real) vintage parts must be a premium in Australia..

    john m
     
  13. EchoWars

    EchoWars Hiding in Honduras

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    Define 'does not work'.

    I never found an application sheet for the STD-series, but the sheet for the SAP-series is around. The devices are identical, except that the STD devices require external emitter resistors whereas the SAP devices had built-in thick-film resistors. In any event, the data sheet for the SAP suggest no additional diode, and only a 200 ohm trimpot between the two diode terminals (preliminary adjustment to zero for minimum idle current).
     
  14. SicMan

    SicMan Fire up those speakers Subscriber

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    yep I know that ... does not work means that I couldn't get the offsets etc and putting the jumper in
    solved that for now. Connects the internal diodes together in each part without the pot and diode in there.
    I picked up a schematic, if I can find it i'll post it ... with the diode in there and I tried the pot only with the SAP16's and couldn't adjust properly. I did not spend alot of time on this stuff as I would like to.
    I'm still on the lookout for an app sheet for the STD series also

    The 9100 bd offset pot, set zero mv offset .. and I did try it in a real unit and it works quite well.
    Be nice to have a doubled up one for the KR9600.
     

    Attached Files:

    Last edited: Feb 23, 2016
  15. Enjoyable

    Enjoyable New Member

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    Hi There EchoWars In 2005 I got a circuit from AudioKarma to replace a blown TA-100WA on a Kenwood Amp. The circuit used MJL4281/4302 output transistors. I built it and installed it and it has worked fine for 10 years. Now it is making bad popping noises and worried it will blow the voice coils. I think you published the circuit. Looking to get advice on how to solve problem. Thanks for your assistance. Richard
     
  16. EchoWars

    EchoWars Hiding in Honduras

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    I've never built it, I only posted a schematic that I thought ought to work.

    Look something like this?

    [​IMG]

    Popping is usually a sign of a failing transistor. I'd power up on a 100W DBT (for safety's sake) and use some freezespray to hit some of the transistors and diodes one-by-one and see what it does to the noise. And remember that these devices in this schematic are really the least likely to have such problems...there's a bunch more semiconductors on that factory PC board,

    I'd be careful about shooting the input FET with freezespray, as offset will go bonkers for 15 seconds or so.
     
  17. Enjoyable

    Enjoyable New Member

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    Hi There,

    That is unreal. Thank you so much for your response. Yes 10 years ago I built that circuit and it works fine until the popping noise. Will follow your advice and let you know what happens.

    Thanks again Richard (Sydney Australia)







     
    dlucy likes this.
  18. EchoWars

    EchoWars Hiding in Honduras

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    Thought I'd add this link to the thread. A really nice replacement for the TA-100W. Page translates OK to english.

    The guy put the trimmer pot between the collector and the base of the bias transistor. Needs to be between the base and emitter. Not sure if the value would have to be changed to get this done...needs some experimentation to see, but overall looks to be a neat solution:

    http://www.suwa-koubou.jp/repair/ka_7500/ka_7500_2.html

    [​IMG]

    [​IMG]
     
    Last edited: Nov 19, 2016
  19. llwhtt

    llwhtt Super Member

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    The trimmer should be between base and emitter, Glenn did a double base-collector. Oops.

    Craig
     
  20. EchoWars

    EchoWars Hiding in Honduras

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    Ha! Missed your reply a month ago. Yep...a bit of a stutter-step there. Fixed...
     

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