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Harman/Kardon HK6500. Loudness not working when button is pressed

Discussion in 'Troubleshooting and Repair' started by Rickedafied, Aug 23, 2014.

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  1. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

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    Nov 28, 2011
    Yes you should replace the eight transistors in the power amplifier section, then run it for a while and see how hot everything gets. If those eight transistors are still getting hot, we can measure some more voltages to see whether they are running at the right current or not.

    How are you dealing with the different pin arrangements of the new transistors? You haven't asked about any of them yet. Those replacements, and the replacements for the phono section (if we decide that they should be replaced), have different pin arrangements so you'll have to cross wires over and use a piece of insulation on at least one wire to stop them from shorting together.

    You can get data on your replacement transistors from digikey.com or nteinc.com. See if you can work out how to fit the replacements in there. If you want, remove the old ones and take a photo of the top side, and either mark the new part connections on the photo, or I can do that.
     
  2. Rickedafied

    Rickedafied

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    Aug 3, 2014
    New pin arrangements? You're not talking about the new transistors for Q531 and. Q532 right?
     
  3. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

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    No. Where are Q531 and Q532? I can't seem them in the parts list.

    I mean that all the TO-92 transistors that look like either one of these pictures. The originals have the Japanese pinout, which is E-C-B looking at the flat face with the pins pointing downwards. The replacements have different pinouts.



    TO-92.png TO-226.png
     
  4. Rickedafied

    Rickedafied

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    Aug 3, 2014
    Sorry I meant to say "you're not talking about Q519 and Q520"

    The new ones I got for Q908 and Q907 were NTE287 and NTE159. They do say EBC on their packages, so they're installed wrong? Maybe that's why Q519 and Q520 are getting hot then?
    I don't remember in any post that you said I was gonna have to cross them or anything lol.
     
  5. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

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    I mentioned pinouts in posts 65 and 110 where I was suggesting replacements, but I didn't explain what they were. I didn't suggest using the NTE devices - I said I didn't recommend them. Whoever suggested them should have pointed out the differences.

    I guess they probably are in wrong. I don't think that will affect Q519 and Q520 but you'd better fix them up!

    Here are the diagrams for the three commonest pinouts for the standard and tall versions of the TO-92 package. All of the devices in your amp use the Japanese pinout. NTE use a mixture of pinouts for their products, but mostly the American pinout I think.

    TO-92 Japanese pinout.png TO-92 American pinout.png TO-92 European pinout.png
     
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  6. Rickedafied

    Rickedafied

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    Aug 3, 2014
    Yeah, the employee there at the time didn't know too much about components and I had to look for things myself.
    Maybe i should go get another set, what if I already damaged them turning the amp on and off all this time. Also it might be easier to modify them with longer pins.

    Ok those 8 other transistors that are getting hot, I'm gonna replace them. So those are ECB pin outs too right? And just to be sure... The NTE55 and NTE377 I had installed for Q519 and Q520, didn't have to be modified right?
     
    Last edited by a moderator: Sep 2, 2014
  7. Rickedafied

    Rickedafied

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    Aug 3, 2014
    The NTE55 and NTE377 packages said their pin outs were BCE
     
  8. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

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    Right, the NTE55 and NTE377 are TO-220 packages - the flat type with the tab at the top for mounting on a heatsink. These are always BCE pinout (at least, I've never seen any exception in 30+ years) so there's no problem there. They are in the right way.

    Yes, the eight transistors that are getting hot are all TO-92 or tall TO-92 packages like the drawings in post #125, and the originals all have the Japanese pinout, ECB. The Fairchild KSA and KSC replacements I suggested in an earlier post have the same pinouts.
     
    Last edited: Sep 2, 2014
  9. Rickedafied

    Rickedafied

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    Aug 3, 2014
    I was able to find four NTE399 with ECB pinouts and four NTE32 with ECB pinouts.

    I couldn't find anything there to replace Q908 and Q907 so I just got the same ones I got before, witch are the NTE287 and NTE159 with the EBC pinouts.

    C411 and C412 are close to those 8 transistors so I though I'd look for some capacitors to replace them. They didn't have any 16V 10uf capacitors but they had two 100V 10uf capacitors. Will those be ok for a replacement?
     
  10. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

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    If they'll fit, yes, but you would be better to buy the right thing from Digi-Key when you order the replacements for Q421~428. Don't tell me you're going to use NTE "equivalents" for them as well. I've looked at the parts that NTE claim are equivalents for the transistors in your amplifier, and they are NOT suitable equivalents. I think they must have been chosen by the NTE marketing department.
     
  11. Rickedafied

    Rickedafied

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    Aug 3, 2014
    So that means I can't use them? Today I went to two different electronics parts stores because one store only had half of the components i needed and i noticed that both stores had mostly NTE components everywhere and both gave me the same NTE transistors. I have no choice right now but to buy from these stores because i cant order from online.

    What will happen if I install them? Am I better off leaving the originals in
     
  12. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

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    Yes you are better to leave the originals in. Perhaps you have a friend who has a credit card?
     
  13. Rickedafied

    Rickedafied

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    Aug 3, 2014
    No, I don't. Can the NTE's for Q908 and Q907 go in at least after I modify them?

    I dont understand, how are they not equivalent? What is it that doesnt match up? Why would they sell them to me if they weren't replacements? Does NTE have a bad reputation?
     
  14. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

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    I don't know what sort of reputation NTE has generally, but they have a bad reputation with me.

    Reputable companies like ON Semiconductor, Texas Instruments, Fairchild, NXP, etc provide complete and detailed information on their products, including minimum/typical/maximum values wherever relevant, and typical characteristics graphs for all of the parameters that are relevant to the component's intended application.

    By contrast, NTE's data sheets give only the most basic information. This implies poor quality control and lack of a responsible attitude to their customers. The fact that they don't manufacture their own devices doesn't excuse them from providing proper documentation for products they re-badge and on-sell. That information would be available from their source companies if those companies had proper quality control. We don't even know who or where they get their components from, and I doubt they would tell you.

    The NTE "equivalents" I've seen are not suitable equivalents. Some have lower voltage and current ratings, and other differences, and all of the ones I've seen have gain specifications that aren't detailed enough to be compared against the original components. So I don't recommend NTE at all.
     
  15. Rickedafied

    Rickedafied

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    Aug 3, 2014
    Ok i understand
     
  16. Rickedafied

    Rickedafied

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    Aug 3, 2014
    Hey Chris, I installed all the parts in the amp and afterwards i powered it on and let it run for about an hour, then I connected my speakers and listened to music for a few more hours with the volume up and so far its working great. The transistors still get hot, but I'm guessing thats probably normal.
     
  17. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

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    OK, if you're happy, I'm happy.

    You might want to crack it open in a month or so, to check that nothing is getting discoloured by the heat from those heatsinks.
     
  18. Rickedafied

    Rickedafied

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    Aug 3, 2014
    Yeah, I was thinking the same thing. Thanks for all your help. I have a stereo receiver I've been wanting to fix also, It doesnt turn on. I haven't opened it up yet. I'm hoping its just cold solder.
     
    Last edited by a moderator: Sep 4, 2014
  19. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

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    OK, if you need help, start a new thread for it.
     
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