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Discussion in 'Marantz Audio' started by Mike Sweeney, Mar 10, 2018.

  1. Mike Sweeney

    Mike Sweeney AK Subscriber Subscriber

    Messages:
    490
    Location:
    Orange CA
    I'm restoring a battered 2285B and it's coming along. I have it working again and the recap is done except for the main amp and the AM/FM board. In the process I had to remove the power amp transistors to re-goop them :D I decided to order up a full set of modern replacements and swap the OEM with new just to see if I can hear any different from the OEM to modern. I'm expecting the new transistors this week from Digikey and I'll swap them in. Has anyone else done this? The OEMs are "Fine" according to testing but the right channel HFE is consistently lower than the left channel by 15 points. Even that is above the min of the data sheet.
    MJ21193G
    MJ21196G

    At the time same I'm replacing the diode arrays on the power supply board with

    VS-MUR1620CTPBF
     

     

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  2. Jailtime

    Jailtime Standin' on a corner Subscriber

    Messages:
    11,406
    Location:
    San Angelo TX
    21194G is the complement to the 21193G. The 21195/21196 have the same ratings, but different gain curves. Dunno how much difference that will make.

    I've only replaced outputs when necessary. I'll be interested to hear if there's an audible or measurable difference.
     
    jstang likes this.
  3. Mike Sweeney

    Mike Sweeney AK Subscriber Subscriber

    Messages:
    490
    Location:
    Orange CA
    Yeah.. but not available right now for some reason. I got the closest replacement I could get. I could not find anything that really stood out that would cause an issue :eek: But I decided since I had it all apart, it would be fun to dabble a bit
     
  4. Ziricote1

    Ziricote1 AK Subscriber Subscriber

    Messages:
    67
    Location:
    N. Virginia
    Interesting, I'm working on a 2285B now as well and was going to order the 21193G and 21194G replacements until I saw they were out of stock. Figured I'll just make do with the originals for now until they get some more in. I would be hesitant to use sets that are not complementary.

    For the diode packs, I used 2x 863-MUR1620CTG and 1x 863-MUR1620CTRG.
     
  5. Mike Sweeney

    Mike Sweeney AK Subscriber Subscriber

    Messages:
    490
    Location:
    Orange CA
    I hear that all the time but the sets here are not that "complementary" there was a pretty significant different between the two banks. I don't know if that is abuse or Marantz was saying "close enough" or truth be told, if I will ever hear the difference :D I will certain post my results. It will only cost me some time, a few pieces of mica and some thermal compound. The transistors are just an investment. If they work well, I'll leave them in .. if not, I'll use them somewhere else and put the OEM back in. If they do work, I might sell the OEMs.. there seems to be quite the market for the OEM cans. I'm not one that believes the OEMs were something magically.. They were picked for the power, curve and low bid. Probably not in that order :D
     
  6. jstang

    jstang Honey,I can't hear you... Subscriber

    Messages:
    3,524
    Location:
    Northern Jersey.....
    The mj21195/6s have a broader SOA.... Which I believe is more critical for an amp that can double down into 4 ohms and high damping factor like the 500. If your amp is current limited into 4 ohms, less need for the broader SOA of 21195/6.

    Think you are mixing terms between complementary and beta matched....
     
    Last edited: Mar 11, 2018

     

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  7. Jailtime

    Jailtime Standin' on a corner Subscriber

    Messages:
    11,406
    Location:
    San Angelo TX
    I hope MJ21193/21194 being out of stock isn't a bad sign of things to come. We'll be doomed if OnSemi discontinues those.

    This 2215 I'm restoring will be an experiment in hearing if outputs can change the sound. I have to go to MJE15032s, since half of the original 2SD315s are missing. TO-66 to TO-220, I'm betting there's no difference.
     
    Mike Sweeney likes this.

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