Marantz Model 4300 needs help

Discussion in 'Marantz Audio' started by AsRock, Apr 27, 2018.

  1. AsRock

    AsRock New Member

    Messages:
    37
    Location:
    Pittsburgh
    Yes i put the details above.

    Right Side
    SJ2517
    SJ2518
    2SC1403
    A475
    All tested good with no leaking with 33-100 gain.

    Left Side
    2SC1403 ( Failed )
    2SA745 ( Failed )
    SJ2517
    SJ2518

    Which is were the other failed parts are.

    And thank You.
     

     

    Please register to disable this ad.

  2. petehall347

    petehall347 the brandy coffee man Subscriber

    Messages:
    25,693
    Location:
    uk.. the middle bit
    2SC1403
    2SA745
    are listed as correct ones .
    just researching ..subs . on semi are good . i only have old sub list and not found a pair yet .
     
    Last edited: May 9, 2018
    AsRock likes this.
  3. AsRock

    AsRock New Member

    Messages:
    37
    Location:
    Pittsburgh
    Well was thinking of just replacing the caps on the power board (P800) and sound boards (P700) and any thing else that was recommended.

    I am after the 2 transistors (2SC1403 + 2SA745) and the following.

    R742 (100Ohm 5% 1/2w
    H715 D357
    H716 B527

    And be nice to replace undocumented resister between H730 & H718, which all i know is 50Ohm ( if memory serves).
     
  4. petehall347

    petehall347 the brandy coffee man Subscriber

    Messages:
    25,693
    Location:
    uk.. the middle bit
    you should at least replace all outputs in blown channel ... working channel should be fine ..so long as those sj ones are suitable .. cant find any reference for those with this unit ..
     
    AsRock likes this.
  5. AsRock

    AsRock New Member

    Messages:
    37
    Location:
    Pittsburgh
    Replace all 4 ?, i thought it would be just the pair. well thanks for looking.
     
  6. AsRock

    AsRock New Member

    Messages:
    37
    Location:
    Pittsburgh
    This post needs deleting.
     

     

    Please register to disable this ad.

  7. petehall347

    petehall347 the brandy coffee man Subscriber

    Messages:
    25,693
    Location:
    uk.. the middle bit
    yes oops .. on my behalf .. one npn pnp pair per channel ..
     
    AsRock likes this.
  8. AsRock

    AsRock New Member

    Messages:
    37
    Location:
    Pittsburgh
    Well i found the parts just waiting on them to get here, should be no llonger than a week. Going go though the thread at least one more time and go though though the tests again as i cannot keep throwing money at it and actually think they are original parts that are being sent. I guess we will see.

    Hopefully they all work when i get them.

    The burned out resister could that of been due tot he transistor failing ? (D357 Or B527). Just trying to get more of a idea what happened and why it failed.

    There is another resister but i cannot find it in the service manual, i have asked about it but no ones responded about it.
     
  9. petehall347

    petehall347 the brandy coffee man Subscriber

    Messages:
    25,693
    Location:
    uk.. the middle bit
    save me reading through again which transistors and resistor ?
     
  10. AsRock

    AsRock New Member

    Messages:
    37
    Location:
    Pittsburgh
    H715 D357 (Short B+E)
    H716 B527 ( short B+E)

    R742 failed open

    Unknown resistor ( working but burned ( 50Ohm )
    [​IMG]
     
  11. petehall347

    petehall347 the brandy coffee man Subscriber

    Messages:
    25,693
    Location:
    uk.. the middle bit
    yes its something to do with those transistors shorted . b to e short is unusual but can happen . did you confirm the shorts out of circuit ?
    i would like to know id of unknown resistor .. can you figure out what each end connects to ?
     
    AsRock likes this.

     

    Please register to disable this ad.

  12. AsRock

    AsRock New Member

    Messages:
    37
    Location:
    Pittsburgh
    Yes i checked were the old transistor were and short as gone in both cases

    Spent a little more time with it and found another short :(, 2SC458 on the same side is all so shorted,i noticed it was their and missed it ^^, so compared with other board and channel and it's surly only one that shows a short. Will have to pick one of those up now to but the guy i got the other stuff of is away until the 20th :(. Once i get the part i will check if the short goes their too when removed.

    I got the unit for $50 so don't mind dropping some money on it as it seems like i could make it back anyways.
     
  13. petehall347

    petehall347 the brandy coffee man Subscriber

    Messages:
    25,693
    Location:
    uk.. the middle bit
    keep checking .. the thing is when in circuit one shorted component can make others appear shorted
     
  14. AsRock

    AsRock New Member

    Messages:
    37
    Location:
    Pittsburgh
    Here's a closer pic of that burned but working resistor and the other from the other channel.

    [​IMG]
    [​IMG]

    I have taken out all the other transistors and they tested all good.
     
  15. petehall347

    petehall347 the brandy coffee man Subscriber

    Messages:
    25,693
    Location:
    uk.. the middle bit
    how many ohms is the good one ?
     
  16. AsRock

    AsRock New Member

    Messages:
    37
    Location:
    Pittsburgh
    Both are 50 Ohm same on the other board too.
     

     

    Please register to disable this ad.

  17. petehall347

    petehall347 the brandy coffee man Subscriber

    Messages:
    25,693
    Location:
    uk.. the middle bit
    h71? it is next to it . 47 ohms . r738 maybe or r737
     
    AsRock likes this.
  18. AsRock

    AsRock New Member

    Messages:
    37
    Location:
    Pittsburgh
    H717\8, Yes that would make perfect sense with the R737\8.

    Thanks.
     
  19. AsRock

    AsRock New Member

    Messages:
    37
    Location:
    Pittsburgh
    Just after a 2SC458,anyone know were i can get one ?, Well i do need the string if anyone has any idea's.
     
  20. petehall347

    petehall347 the brandy coffee man Subscriber

    Messages:
    25,693
    Location:
    uk.. the middle bit
    2sc2240
    or
    KSC1845
    or
    bc550
     
    AsRock likes this.

Share This Page