Onkyo A10 - Power OK, relay click OK, no sound

Discussion in 'DIY' started by paultlaw, Nov 26, 2018.

  1. reddish75

    reddish75 Active Member

    Messages:
    204

    Take the old solder off with desoldering wik clean with isopropyl alcohol and resolder is the best way to do it I've found.

    While the boards are off and if your doing a full restoration replace any relays, zener diodes, fusible resistors clean and reseat any heatsinked transistors replacing mica insulators and new thermal grease, take plenty of photos label any disconnected wires, you can use a toothbrush to clean particularly dirty boards along with something like Mr muscle kitchen cleaner (the one in the orange bottle, it even smells nice) make sure it's rinsed properly after.
     

     

    Please register to disable this ad.

  2. jheu02

    jheu02 AK Subscriber Subscriber

    Messages:
    3,201
    Location:
    North Carolina
    Like radio shack I suppose. A shame!
     
  3. petehall347

    petehall347 the brandy coffee man Subscriber

    Messages:
    28,246
    Location:
    uk.. the middle bit
    and tandy which are long gone .
    radiospares are my go to but dont keep old style pots like they used to .. was a case of getting long shafts and cutting off whats not needed .
    i will look through my stock to see if i have a pot to fit op.s unit if i get chance . no promises . most are old ones solid round shafts .
     
    Last edited: Dec 19, 2018
  4. paultlaw

    paultlaw Active Member

    Messages:
    427
    You are very kind Pete, thanks, I will find one eventually so don't put yourself to any trouble
     
  5. paultlaw

    paultlaw Active Member

    Messages:
    427
    Dirty.
     

    Attached Files:

  6. paultlaw

    paultlaw Active Member

    Messages:
    427
    Before clean IMG_20181219_231515.jpg
     

     

    Please register to disable this ad.

  7. paultlaw

    paultlaw Active Member

    Messages:
    427
    After, poor camera apologies, but chassis now clean in full.
    IMG_20181220_013452.jpg
     
  8. paultlaw

    paultlaw Active Member

    Messages:
    427
    Update, managed to get that pot ordered, from the akai unit as put forward by jheu02, thanks.
    Had to use one of those services that set me up with american address .then its sent to me, no doubt at greater cost. Damn expensive. Let's hope it works, and unit sings immediately.
    Lots of transistors on this that look to be hard to locate suitable replacements/sub's for. Power amp boards are untouched even for cleaning so in the end depending on what needs replacement, and if I have to get 4 new filter caps I'm well into this financially.

    How people make money in this hobby is beyond me.
    My A7090 is also now down a channel so projects are piling up.
    The sa8500 I'm doing for a friend will hopefully be finished this weekend, I hope he likes it, he is in awe of this forum, he thinks its amazing how helpful and knowledgeable everyone here is.
    This is audiokarma
     
    Last edited: Dec 21, 2018
    merlynski likes this.
  9. jheu02

    jheu02 AK Subscriber Subscriber

    Messages:
    3,201
    Location:
    North Carolina
    I know what you mean about projects piling up... anywho, hope the pot works for you. In the meantime, search for Kenwood Basic C2 balance pot. There's a bypass for it involving two resistors that basically completes the circuit, removing the non-functioning balance pot. You could compare the setup and traces and see if jumpering the pot gives functionality while waiting for the new (used) pot to arrive.

    Edit:

    Here's a thread. Post #4 shows the bypass.

    http://audiokarma.org/forums/index.php?threads/kenwood-basic-c2-balance-adjustment-pot.509349/
     
    Last edited: Dec 21, 2018
    paultlaw likes this.
  10. reddish75

    reddish75 Active Member

    Messages:
    204
    Good news on that pot.

    R.e transistors unless there faulty or known to go bad dont replace them, absolutely no need to. I measured the big caps before deciding what to do with this amp, they both measured down on value, esr was fine, to get the amp tested and working they would be fine but wil need replacing down the road.
     
  11. paultlaw

    paultlaw Active Member

    Messages:
    427
    Ok Quick update - the pot finally arrived it is about 8mm longer than the original so i will use jumpers to run to the board.
    I will change out those 2SA726's with some KSA992FBU's on the preamp board and then the unit will go on the DBT
    Ill try get to this asap,as i am very eager to see if we have life.
     

     

    Please register to disable this ad.

  12. paultlaw

    paultlaw Active Member

    Messages:
    427
    So don't think I can make this work, new pot is much larger, won't be able to fit this and make it through front panel, no matter what orientation I put it.
     

    Attached Files:

  13. jheu02

    jheu02 AK Subscriber Subscriber

    Messages:
    3,201
    Location:
    North Carolina
    Wow, that is enormous compared to the other. Question: if the chassis hole was enlarged to take the threaded portion of the shaft, and if you used double hex nuts, one on the inside of the chassis, and one on the outside to be able to set the shaft length correctly, could you then run jumper wires?

    Other option would then be to use resistors across the circuit ala Kenwood Basic C2 balance issue, to at least complete the circuit with fixed balance to test on the DBT. If you're keeping it for personal use, you could then just keep your eye out for an exact parts unit.
     
  14. paultlaw

    paultlaw Active Member

    Messages:
    427
    Nope, won't work in any way, body of unit is way way too big. I'll go visit that thread, I'll take a resistor solution now, spent way too much on that pot.
    On the bright side if anyone wants that pot i got one all cleaned up and ready for use
     
  15. paultlaw

    paultlaw Active Member

    Messages:
    427
    OK so how do I go about this the resistor way? One leg of resistor either side of the wiper, with a single piece of wire going where wiper should be, and connected to one leg of the resistor???
    Trying to wrap my head around this.
    Or do I need 4x 250k ohm resistors and just put one end of each leg where the wiper goes??
     
    Last edited: Jan 12, 2019 at 8:40 PM
  16. paultlaw

    paultlaw Active Member

    Messages:
    427
    Unashamed bump
    Some people bypass the balance pot in the other thread without using resistors.
    If i use the picture as in the other thread and replicate the same with 2x 250kohm resistors and 2x jumper wires, will that work, jumper going from the wiper terminal to one leg of each resistor?
     

    Attached Files:

     

    Please register to disable this ad.

  17. paultlaw

    paultlaw Active Member

    Messages:
    427
    Here is a screengrab of the schematic -showing the balance control



    a10 balance.JPG
     
  18. reddish75

    reddish75 Active Member

    Messages:
    204
    Can you make any measurements on the old pot when at it's centre position?
     
  19. paultlaw

    paultlaw Active Member

    Messages:
    427
    No totally banjaxed unfortunately just have the massive replacement that will not fit - it has no detent either
     
  20. reddish75

    reddish75 Active Member

    Messages:
    204
    Why not try and rebuild the pot? If your not sure post it over and I'll see if it could be saved? Nothing to loose with it at this point.
     

Share This Page