Transistor Substitution for (don't laugh) a Sanyo DCS-3500K

Discussion in 'Solid State' started by ringading, Sep 9, 2017.

  1. ringading

    ringading AK Subscriber Subscriber

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    Location:
    Auburn, WA
    Thanks for the pinout - that didn't come up in my google search. I have the SM now and it shows the pinouts.

    I don't know what the gain is - the information in my previous post is the most i have been able to find. I will try the KSC945s - I have a couple but will need to pick up some more - there are 12 of them on this board and there aren't any other transistors here - just the capacitors and a couple of resistors which almost never go south.

    Aside from the 537s, I can't imagine what else would be happening on this board. Will probably replace the handful of caps here as well while I have access to it. Thankfully it isn't hard to get to.

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  2. Oldsansui441

    Oldsansui441 AK Subscriber Subscriber

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    Yeah good idea to do all of the transistors and caps on this board while you have it out. I would be fairly confident that the KSC945's will work if the gain is similar but it will be a bit of a pain to have to cross the legs over for correct pinout.

    All the best and let us know how it all goes.
     
  3. redk9258

    redk9258 Super Member

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    Illinois, close to St. Louis.
    Would KSC945C be better? Suffix ā€œ-Cā€ means Center Collector (1. Emitter 2. Collector 3. Base)
     
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  4. Oldsansui441

    Oldsansui441 AK Subscriber Subscriber

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    Location:
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    Good call redk9258 :thumbsup:, l had in the back of my mind that you could get some in that orientation but wasn't sure if it was the case for the KSC945's, obviously l didn't study the datasheet enough to see the mention of "C" suffix :rolleyes:. That would make life much easier for ringading's repair l am sure.
     
  5. ringading

    ringading AK Subscriber Subscriber

    Messages:
    527
    Location:
    Auburn, WA
    The 945s I had were center collector so no issues there.

    I checked (all good) and replaced all of the transistors on the SQ board and the problem still persists - little to no sound on the rear channels in any of the 4-channel modes.

    Not sure where to check next. Sounds good in 2-channel mode and in the front channels when in 4-channel mode. I don't think the problem would lie in the CD-4 board as the problem is in Matrix, SQ and CD-4 modes.

    One thing I noticed is that the control for the left rear channel has a lot of bad noise in in even though I have cleaned it a few times. The only other board I have not checked is the EQ board but I would assume that I would have problems on the front channels if a transistor was failing on that board.
     
  6. ringading

    ringading AK Subscriber Subscriber

    Messages:
    527
    Location:
    Auburn, WA
    Coming back around to this after thinking about it for some time. I recapped the SQ board and replaced all of the transistors even though the originals all tested okay.

    I am beginning to suspect the Meter Board. Strange name as this is a small board that contains the pots for each of the individual channels. Channel 1 has lots of noise when rotated even though I cleaned it several times. Meter for Channel 1 jumps around when this happens as well. Also I noticed that Meter for Channel 4 starts out high and then settles down once I work through the 4-Channel options.

    There isn't much on this board - looks like just one cap, three resistors and two diodes for each one. I am thinking that perhaps the germanium diodes may have gone south. I have yet to pull the board as it is crammed in below the meters and is going to be a PITA to get out requiring some desoldering of the leads that go to each of the meters.

    The two diodes are 1S188FM and DS430. I haven't worked a lot with diodes but it sounds like the 1S188 is a germanium. I plan on pulling the diodes and testing them - do you test germaniums the same way you do a normal diode? Any suggestions on a replacement for this one and/or the DS430?

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