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2270 no power

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

  1. MBuras

    MBuras Restoration is an Addiction Subscriber

    Messages:
    433
    Location:
    Champaign, IL
    Hyperion has recommended a BC337 sub over on the Sansui forum recently. And I see Pete just made a recommendation as well. Looks like the main difference is the BC337 has a lower fT than the original (100MHz vs 300MHz) whereas the PN2222ATA is equal at 300MHz. I don't know if the speed is critical at that position so will defer to Pete's recommendation.

    Original SC735:
    http://www.datasheetspdf.com/PDF/2SC735/613419/1

    Fairchild PN2222ATA:
    http://www.mouser.com/ProductDetail/Fairchild-Semiconductor/PN2222ATA/

    Either way the replacements have a center base pinout and will need some lead bending to fit. The original was center collector.
     
  2. petehall347

    petehall347 the brandy coffee man Subscriber

    Messages:
    22,692
    Location:
    uk.. the middle bit
    i looked at the bc337 and that is why i chose the other one . but i didn't check all parameters . just voltage current and ft .
    hfe really needs checking too
     
  3. quadtech

    quadtech Active Member

    Messages:
    469
    I rechecked my thread (it's been a while) and I found that I had replaced H754/H755 (2SC735) with 2N3904
    and it is still working fine to date

    In this thread, blhagstrom recommends a BC635. so looks like you have multiple options.

    http://audiokarma.org/forums/index.php?threads/marantz-300dc-problem.615247/page-2#post-8149318
     
  4. MBuras

    MBuras Restoration is an Addiction Subscriber

    Messages:
    433
    Location:
    Champaign, IL
    The 25 series of the BC337 covers the hfe range just fine as does the PN2222ATA. The 2N3904 sacrifices IC showing a continuous collector current of 200ma vs 400ma on the original but everything else is in line. Looks like each option has at least one sacrifice. Wish I understood the circuits better to know which sacrifices were appropriate.

    :lurk:
     
  5. Dearslayer

    Dearslayer AK Subscriber Subscriber

    Messages:
    554
    Location:
    Ontario Canada
    So many options. I'm not experienced enough to say either way so I will go with the PN2222ATA that Pete suggested. Thanks so much for all the suggestions.
     
  6. Dearslayer

    Dearslayer AK Subscriber Subscriber

    Messages:
    554
    Location:
    Ontario Canada
    It’s been a while since I started this thread and due to uncontrollable circumstances I haven’t been able to devote much time to the repair /restoration of this 2270. I did manage to recap the PS and a little work on the R/S amp board with the gracious help and guidance of Bob ( wlhd1610 ). I replaced H755 -2SC735 with a PN2222ATA as suggested by Pete. The DC offset when checked on the R/S amp was -31.43 V which indicated a problem and the L/S amp was 0.004 . Just yesterday I found that H766 is toast as well on the R/S and will need to be replaced. I do have a few 2N3906 transistors but would I be correct to assume I can’t use it because it would NOT be complimentary to PN2222ATA that’s in place at H755?? I guess the only way I could use it ,is if H755 was a 2N3904 ( that I don’t have ) correct?
     
  7. Dearslayer

    Dearslayer AK Subscriber Subscriber

    Messages:
    554
    Location:
    Ontario Canada
    This is the first unit I've left unfinished for various reasons but I'm now moving forward with it. I have most boards recapped and I'm on the 500 FM detector board and I just noticed an Axial cap at C510. Should I replace it with the same or install a radial cap in that position.
     
  8. wlhd1610

    wlhd1610 Penny and her new friend Subscriber

    Messages:
    1,999
    Location:
    upstate new york
    What does the board pictorial in the service manual show?
    (btw,my 102℉ fever has subsided so I'll be back to help you shortly)

    Bob
     
  9. Steven Tate

    Steven Tate AK Subscriber Subscriber

    Messages:
    1,873
    Location:
    Burleson, TX
  10. Dearslayer

    Dearslayer AK Subscriber Subscriber

    Messages:
    554
    Location:
    Ontario Canada
    Glad to hear your finally feeling better Bob. The SM shows a axial 50V 1uF. I had a radial at that value so I installed that. DBT was ok. Oh BTW I have sound through the headphones on FM and Aux using my phone as a source.
     

    Attached Files:

  11. Dearslayer

    Dearslayer AK Subscriber Subscriber

    Messages:
    554
    Location:
    Ontario Canada
    So should I replace the radial I put in this location with the proper Axial. Will the radial do any harm? I can always replace it when I place my next parts order but that may not be for a bit.
     
  12. Bassblaster

    Bassblaster Super Member

    Messages:
    1,621
    Location:
    Cambridge, Ohio
    Nope. only difference is the lead style.
     
  13. Dearslayer

    Dearslayer AK Subscriber Subscriber

    Messages:
    554
    Location:
    Ontario Canada
    Ok thanks Bassblaster. I just wanted to make sure before going any further and forget all about it ,and not get back to it.
     
  14. Dearslayer

    Dearslayer AK Subscriber Subscriber

    Messages:
    554
    Location:
    Ontario Canada
    Following a cap list that was posted on here and on the Phono 700 board at C713 the SM has the cap listed at 50V 100 uF and that is what I just removed,however the cap list has it at 50V 220uF and that was what I ordered but didn't realize it till now. So is the increase in capacitance intentional or a mistake. I would guess to replace with like value especially where uF is specified. Not sure if I have an extra kicking around at that value.
     
  15. MBuras

    MBuras Restoration is an Addiction Subscriber

    Messages:
    433
    Location:
    Champaign, IL
    That 220 is fine. C713 is the local dc filter and can be increased vs original.
     
  16. Dearslayer

    Dearslayer AK Subscriber Subscriber

    Messages:
    554
    Location:
    Ontario Canada
    Ok thanks Mike. It's funny that you should reply as your thread " 2270 Extreme makeover " was the thread I was reading last night just after I posted. Very interesting thread by the way. I didn't finish that board last night because I worked late and only got that one cap and started to get very sleepy. Thought best to not go any further but I remember having more questions and will check back later. It's off to work I go. Damn shift work. I'm getting way too old for this.
     
  17. MBuras

    MBuras Restoration is an Addiction Subscriber

    Messages:
    433
    Location:
    Champaign, IL
    That seems like ages ago but glad it's still a good reference. I've never done another like that. I just can't hear a difference when changing resistors.
     
  18. Dearslayer

    Dearslayer AK Subscriber Subscriber

    Messages:
    554
    Location:
    Ontario Canada
    Referring to the 700 Phono board

    The cap list I'm using ( don't remember whose list it was ) also has NPN transistors ( ZTX694B ) as replacements for the 458's at H 705/706. I read a lot about KSC1845FTA replacing the 458's so which is best? The 1845 just needs to be turned around whereas the 694 has a different pin out and leads would need some fancy bending.
    Also would the ECQ -E2105KF 250DC 1uF film caps on this list be replacing the glass/silver caps at C709/710/711/712 would you suppose?

    Reading your rebuild back then you had H707/708 replaced with 1N4148 diodes however again this cap list has that replacement part number at 1N4448. Wondering if I would be good with the 1N4448 that I just installed at those locations?
     
    Last edited: Feb 25, 2017
  19. MBuras

    MBuras Restoration is an Addiction Subscriber

    Messages:
    433
    Location:
    Champaign, IL
    I don't know anything about the ztx transistors but the 1845's are fine. 709-712 should be polystyrene caps and will not need replacement. The 1uf Panasonic films might be to replace the .47uf films at 701/702 & 714/715.

    For the diodes, I don't usually use 4448 but from what I understand they're fairly interchangeable.
     
  20. Dearslayer

    Dearslayer AK Subscriber Subscriber

    Messages:
    554
    Location:
    Ontario Canada
    Thanks Mike.
    I used the diodes and changed out the two transistors for now but will wait for someone to help out about the other caps at whatever locations they should go.
     

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