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Marantz 2265b

Discussion in 'Marantz Audio' started by Moby Dick, Feb 18, 2017.

  1. Moby Dick

    Moby Dick Active Member

    Messages:
    100
    Location:
    The Motorcity
    Just picked up a 1978 marantz 2265b one owner in 9/10 cosmetic condition for $50!
    It came with the original owners manual.

    Only problem is owner says it blows a fuse when powered on.

    I have not yet turned it on because I am leaving for Florida tomorrow.

    I am really hoping I am capable of troubleshooting the issue when I return.

    If not, I will take it to a friend of mine who repairs electronics.

    Here is a quick pic for now.
    Now I have to decide between the marantz and my pioneer sx 880!
    Tough choice!

    [​IMG]
     
  2. Punker X

    Punker X AK Subscriber Subscriber

    Messages:
    3,863
    Location:
    Panic in Detroit
    Unlikely that the tuner section of your receiver is blowing the fuse. Typically an issue. Moving to the Marantz forum from the tuner forum. Nice pick up. One of my favorite receivers.
     
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  3. airtime

    airtime Super Member

    Messages:
    1,893
    Location:
    Central Arizona
    I would choose the Marantz 2265b over the Pioneer SX 880. And this is NOT because this is a Marantz forum but because I am familiar with Pioneer gear as well. I was an old Pioneer fan once myself. I really like the SX x50 line. I always thought the SX-750 was perhaps one of the best receivers ever made. And I just loved the early 727, 737 and other models of that era.

    But the 2265b IS a winner.

    You most likely have blown output transistors or a power supply component. Should be an easy. Get it going got now and consider having it restored one day.
     
    Moby Dick likes this.
  4. Moby Dick

    Moby Dick Active Member

    Messages:
    100
    Location:
    The Motorcity
    I opened up the cover on the 2265B to take a look inside.
    It looks untouched.
    I am still waiting on my order from mouser electronics for the output transistors but thought I would poke around and see what I could find.

    I have no electronics training but I checked each output transistor with my multimeter.

    The photos show how I checked each transistor across the two contacts.

    Two of the transistors show OL on my multimeter while the other two transistors show a value on the multimeter.

    Are the two output transistors which displayed OL on my multimeter bad? Or, are the two transistors which display a resistance value bad? Or neither?


    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]
     
    Last edited: Mar 4, 2017
  5. mbz

    mbz Well-Known Member

    Messages:
    553
    Location:
    Melbourne, Victoria
    You should use the diode function on your multimeter to test transistors. There are several AK posts that describe how to
    test a transistor so a search should be performed. Very briefly, a transistor can be modelled as 2 diodes in series. The
    mid point between the diodes is the base connection. Depending on the transistor type (PNP or NPN) it may or may not
    conduct between Base and emitter depending on the orientation of the MM leads. There are 6 combinations that you
    need to work through. OL is ok for some of the combinations, check out the video.
     
  6. mbz

    mbz Well-Known Member

    Messages:
    553
    Location:
    Melbourne, Victoria
  7. dgunnr

    dgunnr Marantz Owner

    Messages:
    143
    Location:
    Southern NJ, USA
    The 2265B is a very nice unit! For that series it has almost all the features the bigger units have. Great looking, especially with the 3 piece wood case. Good luck with the repairs.
     
    Moby Dick likes this.
  8. mfaz28

    mfaz28 Active Member

    Messages:
    101
    Location:
    Bergen, NY
    I had mine overhauled by Catrafter almost 10 years ago. And I still enjoy it thoroughly !!
     
  9. Moby Dick

    Moby Dick Active Member

    Messages:
    100
    Location:
    The Motorcity
    I received my new output transistors and am ready to replace the old marantz transistors.

    I need help cross referencing the new ON part numbers to the old marantz part numbers.

    Which transistors replace which?
    Here are my new ON part numbers:
    Mj21193G
    Mj21194G

    Replacing original marantz:
    B645
    D665

    Any help is very much appreciated.
     
    Last edited: Mar 13, 2017
  10. Steven Tate

    Steven Tate AK Subscriber Subscriber

    Messages:
    1,874
    Location:
    Burleson, TX
    According to datasheetes, 21194 and D665 are NPN and 21193 and B645 are PNP
     
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  11. Moby Dick

    Moby Dick Active Member

    Messages:
    100
    Location:
    The Motorcity
    I have installed the new ON semiconductor output transistors and it powered up without blowing a fuse.
    I tuned in a local fm station and thought all was well until I hooked up my turntable and CD player and noticed distortion coming from the LH channel. Apparently what I thought was FM reception static was actually distortion.

    I thought I would eliminated the possibility of a bad transistor and swapped the transistors with the other side, still severe distortion coming from the LH side.

    So, nothing found after a quick google search. I think my next step is a bias and check D.C. offset.

    Does anyone have any insight on what the distortion from the left channel is?
    I disconnected the turntable and ground to eliminate The phono section.
    I also switched the speaker wire to the second speaker set just to eliminate that.

    Any help I would greatly appreciate.
    I want to get this beauty singing like it should.
     
  12. Steven Tate

    Steven Tate AK Subscriber Subscriber

    Messages:
    1,874
    Location:
    Burleson, TX
    Have you cleaned all of the pots and switches with Deoxit? Lots of these distortions are eliminated by a good control cleaning. Also, try plugging pre-out into another amp to rule out the pre-amp section. Also spray Deoxit into pre out / main in jacks and insert RCA's multiple times to clean the internal pre/main connections. If this doesn't eliminate the distortion, at least you have it narrowed down to pre or main amp to go looking for electronics.
     
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  13. mbz

    mbz Well-Known Member

    Messages:
    553
    Location:
    Melbourne, Victoria
    First up, follow up on Steven Tate's suggestions.
    - clean pots/switches and RCA's
    - use Rx as a seperate PRE then POWER amp to localize the distortion

    Going over the posts, it looks like the only "facts" we have
    is some sort of distortion of LEFT channel. Present on both TUNER
    and AUX so assume PRE and POWER stages.

    Some basic things to try,
    - does the distorting increase with increasing volume?
    (distortion present before volume control)
    - is the distortion also present through headphones?

    The quickest way to track this down is with an oscilloscope, I assume
    you don't have one. Maybe your electronics friend?

    I made the suggestion below on another thread about using a PC based oscilloscope.
    There was no interest. I've used it a few times and the results are a bit "binary"
    (yes/no) which is all you need for tracking down noise sources. I will try and work
    out some good test points for you.



    http://audiokarma.org/forums/index....ight-channel-in-vintage-yamaha-ca-610.751622/

    What about using a PC based CRO, eg,

    https://www.zeitnitz.eu/scope_en

    I use it as a signal generator while saving up for the real thing. Also my cro died before Christmas so I'll probably
    use it. Can't see it being much good, but should be ok for audio frequencies. Uses a 3.5mm stereo jack, ie, need to
    make up your own probes. Also there has been talk that it's tough on the sound card, so if you have an old pc...

    The amp appears to test ok when doing nothing/little work (ok through headphones) but starts to fail when pushing
    "8 ohms". You might get lucky with static testing of TR's etc but...

    The above scope is a free download.

    For what it's worth, I tried the PC based cro mentioned above with reasonable results.
    See pics for diy probe and trace of OUT pin on a CA-1000. Apology for poor photography
    I have no affiliation, other SW CRO programs may be better.
    Its been suggested that such programs may damage your PC soundcard.

    . IMGA0437.JPG IMGA0439.JPG
     
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  14. mbz

    mbz Well-Known Member

    Messages:
    553
    Location:
    Melbourne, Victoria
    Some test points to try with a CRO. Will do more once Steven Tates suggestions have been tried.
    PRE-OUT/MAIN-IN RCA's

    PREAMP STAGE
    Input Pin JE07
    Output Pin JH06
    JH04/05 (L/R?)
    POWER AMP STAGE
    input Pin J702
    Output Pin J706 or Pin J813 on relay/psu board
    J710 and 713 should be tested on the first pass.
     
  15. Moby Dick

    Moby Dick Active Member

    Messages:
    100
    Location:
    The Motorcity
    Than you very much for all the help so far.
    I really do appreciate the input.

    I will separate the preamp stage tonight.
    I will get to the deoxit after that and report back in a couple days.
     
  16. Moby Dick

    Moby Dick Active Member

    Messages:
    100
    Location:
    The Motorcity
  17. Moby Dick

    Moby Dick Active Member

    Messages:
    100
    Location:
    The Motorcity
    Did some more investigating,
    The distortion is present when listening through headphones through the headphone jack.

    I will focus on preamp components.
    Anyone have a wild guess?
     
  18. mbz

    mbz Well-Known Member

    Messages:
    553
    Location:
    Melbourne, Victoria
    Does the Pioneer SX pictured have any option for PRE-OUT/MAIN-IN, I'm not familiar with the model.
    If so, the suggestion was to connect the PRE of one amp, say the Marantz to the MAIN of another, say the SX.
    If there was no Left channel distortion then conclude problem in Marantz power amp.
    If there was left channel distortion then conclude problem in Marantz PRE.
     
  19. Moby Dick

    Moby Dick Active Member

    Messages:
    100
    Location:
    The Motorcity
    so, does the heaphone jack come from the preamp and bypass the power amp?
     
  20. mbz

    mbz Well-Known Member

    Messages:
    553
    Location:
    Melbourne, Victoria
    Pioneer SX-880, no PREout Main in. Do you have another amp or can borrow that does have pre out...
     

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