2270 Bad relay?

Discussion in 'Marantz Audio' started by gregd, Jun 24, 2017.

  1. gregd

    gregd Well-Known Member

    Messages:
    577
    Location:
    San Luis Obispo,CA
    I just scored a very clean 2270 at a garage sale. No click from the speaker protection relay and hence no sound. Using a stick to manually close the relay I can get nice sounding music. I was able to adjust the bias to a couple mV at the speaker terminals but the relay still does not engage ( it was not far off prior to adjustment ). Is there anything else to check or should I just put in a new relay?

    Thanks
     
  2. gregd

    gregd Well-Known Member

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    577
    Location:
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    When I said bias I meant D C offset, sorry I've been reading a lot of threads and terms are getting jumbled in my brain.
     
  3. runningdog

    runningdog AK Subscriber Subscriber

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    Getting the DC offset closer to 0.0mV if possible will be good, but a couple of mV should not be enough to keep the relay from closing. The other setting is bias (idle current). If the serial number of your 2270 is >3900 (most are), measure across J754 to J760, set R763 for 10mV. Let it warm up for 30 minutes first.

    Some possible issues related to the relay:

    1. The relay is working as it should, meaning there is an issue with one or both amps.You can disconnect the amp audio outputs one-at-a-time from the bottom of the P800 power supply to see if the relay closes when one or more amp outputs are disconnected.
    2. The relay is working but the protection circuit has failed. A common cause for this is H808 on the P800 power supply has failed.
    3. The relay is not working and needs to be replaced.
     
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  4. gregd

    gregd Well-Known Member

    Messages:
    577
    Location:
    San Luis Obispo,CA
    Thanks runningdog.
    I set the bias but the relay still does not click. When I engage it manually it feels kind of buzzy and that goes away when it is engaged. The pins on the relay that are unmarked, I am guessing are the ones that energize the seloniod, have 18v and 26v on them if that tells you anything.
    I was going to disconnect the amp audio outputs to further diagnose but I'm not sure which ones they are.
     
  5. runningdog

    runningdog AK Subscriber Subscriber

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    299
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    On a 2270 the wires from the amplifier outputs to the relay typically are blue and yellow. Those are soldered on closer to the middle of the bottom of the power supply and are the ones to disconnect to test. Then typically there are gray and orange wires leading away from the relay.

    When you close the relay manually does it stay closed?
     
  6. gregd

    gregd Well-Known Member

    Messages:
    577
    Location:
    San Luis Obispo,CA
    No, it does not stay closed.
     
  7. runningdog

    runningdog AK Subscriber Subscriber

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    I'm sure you know this but be very careful to not ground the blue and yellow wires when they are disconnected from the power supply. And turn it off in-between each change to the wiring. Turn off the speaker Main and Remote to spare your speakers from a mistake, if they are hooked up. It wouldn't hurt to have it on a DBT while you are doing this.
     
  8. gregd

    gregd Well-Known Member

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    577
    Location:
    San Luis Obispo,CA
    Thanks, will observe all precautions and won't be getting back to it till tomorrow since I had a beer with dinner and plan on another.
    I have read many threads about this relay being problematic but the failure mode seems more related to bad contacts and not the seloniod portion.
     
  9. gregd

    gregd Well-Known Member

    Messages:
    577
    Location:
    San Luis Obispo,CA
    The relay still does not engage after removing the blue and yellow wires.
     
  10. runningdog

    runningdog AK Subscriber Subscriber

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    299
    Location:
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    That's good news, it means the amplifiers are not the issue. Which narrows it down to the relay, or the protection circuit. It's probably worth ordering a relay and the H808 transistor to be covered. It's possible it is another part of the circuit but H808 is what seems to fail.

    H808 --> 2SC945 --> KSC945 or KSC1845 (others, please chime in on this transistor choice)

    L801 --> MY2 --> Omron MY2 DC24
     
  11. gregd

    gregd Well-Known Member

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    577
    Location:
    San Luis Obispo,CA
    Thanks for the guidance, I'll get those parts coming.
     
  12. catrafter

    catrafter Marantz Specialist Subscriber

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    2SC945 = KSC945C The final 'C' gets you a part with the collector in the center like the original.

    Tom
     
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  13. gregd

    gregd Well-Known Member

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    577
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    I can get a MY2N dc24 without paying shipping, looking at the specs it seems the same except that it has an led indicator, anyone have experience with that?
     
  14. Shain

    Shain AK Subscriber Subscriber

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    It would be advisable to recap the power supply board.
     
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  15. runningdog

    runningdog AK Subscriber Subscriber

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    The MY2N 24DC (S) version has the useful topside indicator and is widely available.
     
  16. gregd

    gregd Well-Known Member

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    577
    Location:
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    I probably will, but since I've been known to introduce more problems than I solve with such things I want to get it working first.
     
  17. gregd

    gregd Well-Known Member

    Messages:
    577
    Location:
    San Luis Obispo,CA
    I put in the new relay and h 808 transistor and still no action. I may have installed the transistor incorrectly. All the references to the npn transistors are constructed as follows; looking at the flat face with the numbers on it, going from left to right it is, emitter, base, collector. I could not find one with the part number ending with a 'C' so I am assuming the ones I got follow the standard convention. I can find no reference as to the construction of the KSC945 so perhaps they are not emitter, base, collector.

    The my2 relay is a 24v relay which I assume is the voltage necessary to energize the coil, I am getting 32v on both the pins at the top. Does this tell us anything?

    I'll be the first to admit that I'm pretty amateur when it comes to this stuff but a relay is a pretty simple device, am I missing something?

    Thanks for the help.
     
  18. Bert 1100

    Bert 1100 Well-Known Member

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    Planquiri !
  19. gregd

    gregd Well-Known Member

    Messages:
    577
    Location:
    San Luis Obispo,CA
    In an effort to figure out the pins on this transistor I found some things, first the old one appears to not flow current in any direction so I'm guessing it was bad. The new one flows current from the center pin (base?) to the left side pin (emitter?) but not from the center pin to the right side pin ( collector?). This was with the positive probe on the center pin and the meter set to Ohms and the flat side with the part number facing me. I'm confused. I tried all other combinations and only get flow from center to left.
     
  20. gregd

    gregd Well-Known Member

    Messages:
    577
    Location:
    San Luis Obispo,CA
    Thanks for that Bert. I got that in there correctly now but still no contact.
     

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