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New bench project, 2245

Discussion in 'Marantz Audio' started by Mike Sweeney, Nov 1, 2018.

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  1. Mike Sweeney

    Mike Sweeney AK Subscriber Subscriber

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    420
    Location:
    Orange CA
    Here I go again.. another Marantz but since I just cleared three Kenwoods off the bench, it's time again :)

    This one has had someone in it who was a bit of a hack. Transistors are not OEM.. a few caps replaced and not well, speaker relay replaced at one time etc.. Plus the normal burned out lamps and one very cooked power switch even with the snubber. This follows how I normally do things.. inspect for obvious signs of issues and if nothing stands out, then take apart the power switch and clean it or replace it and replace the main filter caps. Then I'll apply some power in a limited form to see what happens. I can pretty much say every Marantz I've worked on so far, one or more main filter caps has been outright bad or leaky and half the power switches are cooked. I went ahead and scrubbed the selector switch, volume and balance pots. They get heavy use and tend to be in need of attention. I'm waiting on some more snubbers right now.. my last one got used on my KT-5500.

    I went ahead and put in the new LEDs since I had them at the ready :)

    This will be a fun one I think :)
     

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  2. Steven Tate

    Steven Tate AK Subscriber Subscriber

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    I just love this model. Keep us posted on the progress. :thumbsup:
     
    Mike Sweeney likes this.
  3. audiojones

    audiojones Jonesin' for audio Subscriber

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    My favorite of all the 22xx models. Get 'er done! :banana:
     
  4. Mike Sweeney

    Mike Sweeney AK Subscriber Subscriber

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    Location:
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    So the power supply board is done and the filter caps are done. But the unit wouldn't come out of protection mode. Adjusted voltage etc.. and no joy. So I moved on to the amps. I knew the transistors had been butchered from some pink shit someone used for compound in the distant past. I pulled the right channel first and the PNP was way low for hfe but working after a fashion. NPN looked pretty good. But I have new for both sides so I went ahead and replaced the caps ( 2) plus the .1uf with new films. I need to get some 1ufs I'm out and didn't remember to restock :/

    To get these boards, I had to cut them out and I will just re-wire them back in with new wire. Does anyone know a source for the thin coax they use? I can look but it's easier to ask. Anyways.. the left channel is where all the fun is.. the PNP had two micas with pink shit everywhere.. and it's shorted. And thats not counting the lack of solder on the lead :eek: A real hack was here.. And someone had pushed a resistor into a 2nd one and shorted them out. I am wondering what else I'll find bad on this board now :/ That explains not coming out of protection.. go figure ;)

    IMG_6894.jpg IMG_6897.jpg IMG_6914.jpg IMG_6915.jpg IMG_6916.jpg
     
  5. catrafter

    catrafter Marantz Specialist Subscriber

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    Mike,
    I believe it is just shielded wire. You should be able to use coax though, I think RG-174 is about that size.

    Tom

    P.S. With a little fiddling around, you can get the boards positioned where you can work on them without disturbing any original wiring.
    T.
     
  6. Mike Sweeney

    Mike Sweeney AK Subscriber Subscriber

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    Location:
    Orange CA
    I just ordered some guitar shielded circuit wire. It comes in colors so I can match the OEM colors and it's thin for use in the guitar body. Braided shield so I'll put up some pics when I get it next week. These amplifier boards looks have been wired then mounted and the wires then run to the end points. There is no way to get to the posts without either unsoldering the end point then pulling it back out or snip then splice or rerun it. I will be rewiring them into the chassis for a clean job of it. It's not that big of deal for this unit. I'm hoping the guitar wire works out well :) I'll have pics up of it all as normal :)
     

     

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  7. Mike Sweeney

    Mike Sweeney AK Subscriber Subscriber

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  8. Mike Sweeney

    Mike Sweeney AK Subscriber Subscriber

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    Location:
    Orange CA
    So I'm in a quandary .. the left side amp has been butchered.. bad power transistors.. burnt resistors.. but, the board transistors "seem" to be OK.. in other words, in circuit testing shows they match side to side and no dead shorts that I can see. Whoever worked on this swapped one 100 ohm resistor like it should be.. but the other measures at 500K .. the bands are so burnt I can't tell now. And it was a mother of a resistor.. 5 watts I'm guessing?

    Do I leave it and just get a replacement board.. or rebuild and hope for the best .. opinions?
    IMG_6923.jpg
     
  9. EastPoint

    EastPoint Factory Code No. 4200 Subscriber

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    Just check the manual for the resistor size. I’d rebuild the board. If you feel really uncomfortable you can shotgun the transistors.
     
  10. wlhd1610

    wlhd1610 Penny and her new friend Sponsor Subscriber

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    I'll send a replacement board,dont mess around with it.
    Bob
     
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  11. Mike Sweeney

    Mike Sweeney AK Subscriber Subscriber

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    Very generous.. thank you.
     

     

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  12. Mike Sweeney

    Mike Sweeney AK Subscriber Subscriber

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    Murphy is alive and well. The copy of the service manual we have here is missing that page :/ I'm hunting for it later tomorrow. The schematic is good.. damn nice actually. So I'm not too worried about figuring it all out.
     
  13. EastPoint

    EastPoint Factory Code No. 4200 Subscriber

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    Did you check hifiengine for the manual?
     
  14. Mike Sweeney

    Mike Sweeney AK Subscriber Subscriber

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    Yep.. that was my first source with the error. I found the same PDF in a dozen places. I ended up paying 16 bucks to servicemanuals.net for a very clean scan that is complete with the missing pages and a few extra schematics. Apparently there were design changes between batches of serial numbers. I need to look mine up tomorrow and see where it falls into this new info. I'm curious now how the schematics differ since there are three based on the SN.
     
  15. Mike Sweeney

    Mike Sweeney AK Subscriber Subscriber

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    Location:
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    Getting the amp boards re-wired. Like I said earlier, it was easier to cut the boards out to have them free of the chassis. I am betting they put them in like this. With the wires attached and then they routed them to the end point. This will make a nice clean job of it.
    IMG_6969.jpg
     
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  16. Mike Sweeney

    Mike Sweeney AK Subscriber Subscriber

    Messages:
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    Location:
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    I mentioned to a few folks that I ordered some guitar shielded circuit wiring to use as a replacement for the shielded wires in the 2245. It's almost a perfect match. I redid the leads from the P750 boards to the respective jacks on the back. The old wiring was ratty and hard to work with given how the P750s are mounted. So I made new runs.

    IMG_6987.jpg IMG_6990.jpg IMG_6997.jpg IMG_6998.jpg IMG_6999.jpg
     

     

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  17. Steven Tate

    Steven Tate AK Subscriber Subscriber

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    Nice work! :thumbsup:
     
  18. Mike Sweeney

    Mike Sweeney AK Subscriber Subscriber

    Messages:
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    Location:
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    Bob's replacement board showed up (Thank you!!) And its been refurbished and ready to put back into the chassis. New electrolyic caps, new 100 ohm resistors and new films plus new wiring for both the shielded and unshielded cross connections

    039C6362-FA95-4965-9A20-172835B0B069.jpeg
     
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  19. Mike Sweeney

    Mike Sweeney AK Subscriber Subscriber

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    Getting the amp boards done.. finally ;) What we have here is the replacement pots which were hard to find at 2.2 K with the side adjustments. Then I had to replace all four transistors. What I did here was use new hardware plus washer and lock washer. My 2285 had this so I borrowed the idea. I had to get new screws anyways.. so I just got them a bit longer to account for the added thickness of the two washers.

    I should be mounting the left channel amp tomorrow with all the new cabling in place and if I'm lucky, I'll have time to do the right channel too. I do plan to jump them into place first and apply some power for testing.
    IMG_7171.jpg IMG_7172.jpg
     
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  20. Dingman

    Dingman Do you know where your towel is? Subscriber

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    Looking good.
     

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