2270 no power

Discussion in 'Marantz Audio' started by Dearslayer, Dec 5, 2016.

  1. Dearslayer

    Dearslayer AK Subscriber Subscriber

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    I'm just finishing up the 400 preamp board on this 2270 and I'm wondering if I should replace the two big Green caps at C401/402. They appear to be 50V .22uF. Only ones I have are Panasonic 250VDC 0.22uF Mouser pt# 667-ECW-F2224JAQ. If I should replace them would these be ok or should I leave the Greenies in place?
     

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  2. Steven Tate

    Steven Tate AK Subscriber Subscriber

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    I have replaced them with the Panasonics, replaced them with the Mundorf EVO Oils, and left them alone. My ear can't tell the difference. But...currently I replace them with the Panasonics just to get new ones in there.
     
  3. Dearslayer

    Dearslayer AK Subscriber Subscriber

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    Thanks Steven. Stupid question but does it mean the same thing when the value is stated such as DC ( direct current ) and VDC ( Volts Direct Current ) I noticed it on some packages from Mouser, that some have the value description defferently.
     
  4. Steven Tate

    Steven Tate AK Subscriber Subscriber

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    I think it's all the same. I have used 250v and 450v Panasonic polypropylenes and both seem to work fine. They look the same and are about the same size. Maybe someone knows if there is a specific "best" replacement in this spot.
     
  5. Dearslayer

    Dearslayer AK Subscriber Subscriber

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    Just about finished with the 2270 other than changing out the Vellum and replacing new LEDs. All spec settings check out spot on, except the bias on the right amp ( where I had to change out the drivers on that amp board to the TO- 220's) it sits at 15.4mV ( spec is 5mV ) and that's after letting it stabilize. I'm guessing I will have to change out the bias transistor at H760 with either a MJE243 ( back ordered at Mouser for 6 weeks ) or KSC3503DSTUFS as was suggested by Bob. Until I get an order in to Mouser for other parts needed for the next build is it ok to use this unit with the 15.4 bias on that right amp or will it do harm?
     
  6. Steven Tate

    Steven Tate AK Subscriber Subscriber

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    Catrafter reminded me that on the 2245 and 2270, if you are measuring bias between J754 and J760, the setting should be 10 mV.
     
  7. Dearslayer

    Dearslayer AK Subscriber Subscriber

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    I was instructed to measure at J756 and J754 for 5mV ( maybe that was an oversight ) , even though the Service manual Error post states .

    2270 SN>3900 Idle current or bias adjust:
    Meter set to read DC mV, connect from J754 to J760, set R763 for 10mV

    My serial number is 82553

    I will try that again tonight then to see if it makes any difference. Hopefully it will and I won't have to take that amp out again to change that transistor. Thanks.

    G.T
     
  8. Steven Tate

    Steven Tate AK Subscriber Subscriber

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  9. Dearslayer

    Dearslayer AK Subscriber Subscriber

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    Just looking at the schematic real quick here at work ,but wouldn't J754 and J756 be the same for 5 mV because it only goes across 1 resistor as opposed to two??
     

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  10. Steven Tate

    Steven Tate AK Subscriber Subscriber

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    Probably, but if nothing else, 760 is easier to get to than 756. It's easy for me to remember to just clip onto the third pin from each side and set to 10mV.
     
  11. Dearslayer

    Dearslayer AK Subscriber Subscriber

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    That is true. I always have to refer back to my notes. Old age sucks.still would like to know if the 15.4 bias on that Amp will do harm if used.
     
    Last edited: Mar 9, 2017
  12. Steven Tate

    Steven Tate AK Subscriber Subscriber

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    I've had two 2245's that wouldn't bias out properly -- close but no cigar. I took rBuckner's advice and replaced that bias transistor with MJE243G's and it fixed both of them. Very easy fix.
     
  13. Dearslayer

    Dearslayer AK Subscriber Subscriber

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    Cool but it will have to wait for 6 weeks till mouser gets them in. I will check other sources in the meantime. Looks like Digikey also backordered.
     
  14. Steven Tate

    Steven Tate AK Subscriber Subscriber

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    PM me your address and I'll send you one. Wonder how long it takes mail to get from Texas to Canada?
     
  15. rBuckner

    rBuckner Luv 2 Restore Subscriber

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    No it won't but if it leads to thermal runaway it will! I'd recommend monitoring the heatsink temperature somewhat often to be sure.
     
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  16. Dearslayer

    Dearslayer AK Subscriber Subscriber

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    Thanks Mr Buckner. I have no reason to actually put it in the loop just yet other than on the bench to let it Break In sorta speak, but was worried that even that might do it some harm so good to know. If I run it for any extended period I will monitor the heatsink Temps for sure. Thanks for the advise.
     
  17. rBuckner

    rBuckner Luv 2 Restore Subscriber

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    You're welcome and please.. call me Randy. Mr. Buckner was my Dad's name!! :biggrin:
     
  18. Dearslayer

    Dearslayer AK Subscriber Subscriber

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    Hahahaha no prob Sir...it's just habit. My Grandfather raised and taught me, and I still call the female gender ( any age ) Ma'am. Randy it is then.
     
  19. Dearslayer

    Dearslayer AK Subscriber Subscriber

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    Noticed today while I had the TT hooked up for testing to see Phono 1 input was ok,that after about 20-30 minutes the left channel started to drop. Not completely but about 75%. All other inputs are fine except the Phono. Even Phono 2 was the same. I listened to music on my IPhone through Aux for a couple hours and there was no channel drop. Same for FM all good. Any ideas? I haven't tried a different TT yet.
     
  20. Steven Tate

    Steven Tate AK Subscriber Subscriber

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    You might want to replace those four 2sc1000 transistors. I think KSC1815YTA works in those spots.
     

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