2sa684 replacment

Discussion in 'Pioneer Audio' started by Tod denneny, Feb 4, 2018.

  1. Tod denneny

    Tod denneny New Member

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    Yes can be done but without the old boards parts cant be found...in my case i only had one board and needed three.
    I tried to source the old connectors not possible.

    On the last few Sansui boards i produced i used PC power supply connectors that way the board was plug and play.
    In the case of the 1250 the connector protruded out of the board way to much
     

     

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  2. Tod denneny

    Tod denneny New Member

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    I see what i can do about getting you a board when i send out for a new order i only had two extra and just sold one of the two.
     
  3. rcs16

    rcs16 Super Member

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    Nice to see someone working on new pcbs for this old gear. way to go.
     
  4. kramden

    kramden Active Member

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    158
    The 939/1010 power supplies would be excellent candidates. Many are charcoal.
     
  5. Tod denneny

    Tod denneny New Member

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    if we need them i will produce them ...just need to make sure they will sell
     
  6. Tod denneny

    Tod denneny New Member

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    20180206_191949.jpg almost done :) waiting for a few parts :banana:
     

     

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  7. markthefixer

    markthefixer On Hiatus, dealing with Dad's estate full time Subscriber

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    I don't want to rain on your parade, but since these particular boards are connected by pins and connectors in the unit AND you mentioned a commercial aspect, it would be a far better selling point that besides fitting into the available space, that they also accept the connectors. Worth a try.

    I would like to get the part numbers on those large rectifier bridges, I want to do some technical evaluation / analysis.
    It will be interesting to see how well those heat sinks dissipate when not in their normal plane of operation.
    I UNRESERVEDLY acknowledge that these new heat sinks are FAR better than those implemented by the factory.

    The one thing I REALLY LIKE in electronics is thermally cool power transistors
    and their heat sinks that are doing their job by coupling the heat to the ambient environment.

    How many layers are on these boards, and if multilayer, are they plated through?

    Thank You.
     
  8. Tod denneny

    Tod denneny New Member

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    31
    GBJ2510 Rectifers
    Two layer plated Tr
    2mm board thickness 2g copper traces
    There is a lot more to think about when producing boards all the calculation for trace size are a pain..

    I would love to see them with factory connector let me know what you fine and i can easily change PCB
     
  9. rcs16

    rcs16 Super Member

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    Exactly and how does one know what the demand will be?
    If you do the design for your own use, then there is the added benefit to sell some.
    We know it will be low volume but where do you draw the line at what number it is worth the time to engineer.
    If you re-do the design, then why not add some extra features like current limiting to the series pass regulators, the extra parts are trivial. Or replace some regs with IC equivalents that have built in CL or better performance.
    I am not a fan of using the old connectors knowing that they are tarnish sources, much better to change the connector to a gold plated design. yes it requires one to have to re-wire, but the gain is worth it imo. I guess you can have two versions, one original and one upgraded.

    On one power amp rectifier design I used
    512-GBPC3508W
     
  10. Tod denneny

    Tod denneny New Member

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    100% Agree but from pass experience everyone want the boards to be as close as i can get them to original design. I agree with them when it comes to power amp boards QE boards any board that has an in-pack that can change the overall sound quality next to the original sound.
    But when it comes to power supplies and stabilizer boards the better built boards will serve the original boards much better performance.

    PS the GBPC2508W is also a good choice
     
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  11. markthefixer

    markthefixer On Hiatus, dealing with Dad's estate full time Subscriber

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    Very nice rectifiers, 350 or 400 Amp surge, both have holes for bolt on heat sinks.
    The specs for the GBJ2510 (25A) mention a 250mm x 250mm x 20mm aluminum heat sink for 83 watts, and spec a thermal resistance..
    You have left PLENTY of correctly orientated airflow area for a bolt on heat sink - it won't be the full 83 watts in their spec
    (the forward voltage is about 1.0 as usual, so amps current translate closely to Watts to shed.) so a much smaller one will suffice.
    remember, the original diodes were mounted on a metal strap that doubled as a pretty effective heat sink.
    The only different one on many of the units I have encountered that comes to mind was the SX-1050's AWR-104 board
    which used a KBH25-04 bridge and a U shaped heat sink about 1.5 inches on each of three sides.
    So heat sinking on the high power rectifiers is not to be ignored.

    A small CPU type heat sink (plentiful, cheap) with one sheet metal screw through a hole in the bottom, with some thermal grease will be easy to implement.

    As for the connectors, easy peasey - just implementing a second row of PC board holes with the correct size and spacing would be enough to allow people to transplant the existing connector onto the board, you can just ship it with the phoenix separate and let them choose which to install.
    Rick has a point about the tarnishing, but this obviates having two versions of the boards.

    p.s. I'd LOVE to find nickel or gold or just plain non-tarnishing pins.

    And YES, I have personally transplanted pin connectors from board to board. AND model to model donors.
     
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  12. Tod denneny

    Tod denneny New Member

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    Really enjoy the feedback guys i should have being sharing the other boards i have produced
    my next board is a sansui F 2980 this one will take me 4 or 5 weeks to complete a customer has being asking for this board for a few months now...
     
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  13. Hipocrates

    Hipocrates Anti-Muppet

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    Keep them coming man, IMO, this is invaluable!
     
  14. rcs16

    rcs16 Super Member

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    Good luck on the F-2980, much bigger job for sure. I have an old one (from a G-7500) that has of course smoked traces on it.
    Hope it works out okay for you. the biggest problem with that design was that the o/p bjts were way underrated for the rail V. Anyone driving it hard or driving lower Z speakers, smoked the o/p bjts and traces on the pcb.

    Mark makes a good point about putting a HS on the bridge rectifier. I used a self adhesive pin array CPU type HS on the GBPC3508W version. The one on the SX-1050's AWR-104 board is made of steel.
     
    Last edited: Feb 8, 2018
  15. Tod denneny

    Tod denneny New Member

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    Willing to produce this board but would need a used one just for sizing ....no parts or a really good measurements of the board and mounting hole locations
     
  16. markthefixer

    markthefixer On Hiatus, dealing with Dad's estate full time Subscriber

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    I shouldn't have let that get by me.

    The SX-939's AWR-052 power supply is VERY different from the SX-1010 power supply AWR-054.

    So it would just be for the SX-1010.
     

     

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  17. Hipocrates

    Hipocrates Anti-Muppet

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    @Tod denneny, I think the Yamaha CR2020 could use your skills too! Not to mention the sansui 9090 and the F-2436 and F-2541, not sure how big can be the market though.
     
    Last edited: Feb 12, 2018
  18. Tod denneny

    Tod denneny New Member

    Messages:
    31
    Just sent both boards back to change connectors to plug and play......... Worth the cost...
    Installed both REV1 Boards today and work perfectly :) but really hard to wire with these current connectors...not much room once board installed to connect wires. Anyway did not like it so changed PCB to new connectors digikey WM14975-ND
     

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