Pioneer SX-737 Restoration

Discussion in 'Pioneer Audio' started by Spenser, Jan 29, 2018.

  1. Spenser

    Spenser AK Subscriber Subscriber

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    Last edited: Feb 6, 2018
  2. loweran

    loweran AK Subscriber Subscriber

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    It ain't so bad man.
     
  3. Motnick

    Motnick AK Subscriber Subscriber

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    I made the exact same mistake with my parts order when I redid my SX-737.

    653-LY2F-DC24 was what I ordered the second time around. I was even able to snap the new relay guts into the original relay housing so that it would mount into the unit without any fuss.

    [​IMG]
     
    Last edited: Feb 6, 2018
  4. Spenser

    Spenser AK Subscriber Subscriber

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    Hey Motnick! Man that's good to know. I thank you!

    Might see if can order the standoffs from Mouser anyway for insurance. That way we know for sure it will snap right in there. Thanks again!

    I went over and posted a quick note to the thread that contained the LY4F on the BOM spread sheet.
     
    Last edited: Feb 8, 2018
  5. larryderouin

    larryderouin You can be sure if it's Westinghouse??????? Subscriber

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    GUYS! The LY4F-DC24 is the correct replacement. If it's NOT AVAILABLE the LY2F-DC24 will work. All you are doing here is NOT jumpering 2 poles on the LY4F-DC24 with the LY2F-DC24. Even tho the LY2F-DC24 will work, the LY4F-DC24 will last longer as the contacts are "bridged" so they are sharing the load which is halved on each of the contacts compared to the LY2F-DC24. (ie: 4 contacts is better than 2 for longevity). I've done the same thing as Motnick with the LY4F into a 1010, a 939 and a 737 and they all work. This is going back to 2010 for the 1010. See my post on the other 737 thread. It has Mark the Fixer's list of single relay units that take these (LY4F-DC24 PRIMARY.......LY2F-DC24 SUB) relays, and the link and post # this came from.
     
  6. Spenser

    Spenser AK Subscriber Subscriber

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    Au contraire. Now there appears to be considerable difference in dimensions. See pages 7-8 of datasheet. The one in my hands (LYF4-DC24), at the base (without case), meaures 40.66 x 26.96 mm. I don't have the old one pulled yet but it looks like around 24.58 x 19.27 mm. The LYF4-DC24 is quite a bit larger.
     
  7. larryderouin

    larryderouin You can be sure if it's Westinghouse??????? Subscriber

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    It looks like OMRON changed the design and dimensions of the damned thing. This has been the go to relay for over a decade. This is a 4 year old LY4F-DC24 in my SX-939. Note the orientation of the contacts. There are 16 on it. Looks like they turned it 90* and enlarged it. Can you VERIFY the dimensions of the one you have in hand? Actually the Ly4F is shown on PAGE 9. I'll let MARK KNOW what's going on.
    [​IMG]
     
    Last edited: Feb 7, 2018
  8. larryderouin

    larryderouin You can be sure if it's Westinghouse??????? Subscriber

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    I'll open up my 737 as it's the easiest to get to, and check the dimensions. It'll be later today as I have to go watch the grandkids today.
     
  9. Spenser

    Spenser AK Subscriber Subscriber

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    Gunga Din.
    LY4F-DC24 02-07-18.jpg
     
  10. larryderouin

    larryderouin You can be sure if it's Westinghouse??????? Subscriber

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    Oh YEAH! They redesigned it. QUESTION. Will the tabs fit with the screw holes, so you can hang it underneath????? And is there enough room to do so below. I just got home. Grandson has pylonephritis and cystitis(Kidney and bladder infection per the urine samples son took in). Pumped him full of Cranberry Juice and 7-Up(50-50). I have to learn what 6 year old girls like to eat, wear, play with, etc. as we had boys, no girls and let my late wife handle the granddaughter with regard to those things. I just passed out $$$. Grandson's are a lot easier. Get them Tonka Trucks and Hess Toy Trucks, Diecast cars, etc. and they are fine.

    If the hole and the dimensions the the LY2F-DC24 are approx the same, by all means use it.
     
  11. larryderouin

    larryderouin You can be sure if it's Westinghouse??????? Subscriber

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    O-fish-ul word from Mark the Fixer. DELETE the LY4F-DC24 and sub in the LY2F-DC24. The LY4F WAS substantially re-designed.

    My comments. Looks like a Typical GOV'T Contract where they spec a small single seat Attack or fighter(A-4 or F-16) and end up with an ELEPHANT the size of a A3D Whale/B-66 Destroyer with less capability, 1/3 the range and 6 times the fuel usage. The cost goes from 10million a copy to 200 million a copy, and the Pilots damn near revolt. .
     
  12. Spenser

    Spenser AK Subscriber Subscriber

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    Hey Larry. Hope your grandson gets over his infection quick and easy. Good thing you guys caught it. And don't worry your granddaughter will school you. Ha. It was all girls in my household.

    That redesigned relay. Razzle frazzle sugar bleep. Yes well. You guys are right. No good. Tabs are now catty corner; the redesigned version is like twice its original size; would have to enlarge the mount opening in the chassis, tap, etc. I'll be ordering the LY2F-DC24. Motnick said the experience with his SX-737 was a good fit. In his case new guts snapped right in the old housing. He put up a picture on Post #23. I will probably still see if I can get four standoffs in order to have the option to configure Echowars-style.
     
    Last edited: Feb 8, 2018
  13. larryderouin

    larryderouin You can be sure if it's Westinghouse??????? Subscriber

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    All of mine had the tab's on the top of the case, so I swapped cases and installed. It's a bit tight but it works quite well. Hope these last longer than the originals.......
     
  14. Spenser

    Spenser AK Subscriber Subscriber

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    Report 3: Power Amplifier Board. I've gone ahead and changed out all the power amplifier electrolytic capacitors and the trim pots.

    Opinion Poll. Replacement of what power amplifier transistors is warranted?

    How do you vote?

    The two on our "most wanted" list 2SC1451 -- Q5, Q6 -- they're already out and replaced.

    Next up... Q1,2,3,4 all have the factory 2SA763 (not 2SA726). Should they be replaced?

    And what about the driver transistors Q7-10 replace?

    What about the output transistors Q11-14 replace?

    See schematic attached below.

    What say you!?!?

    Thank you!
     

    Attached Files:

    Last edited: Feb 9, 2018
  15. markthefixer

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

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    There is no real reason to replace any (all or nothing?) others. You might get a an improvement in sound, or not.I'm not sure how well 2sa763's age,.

    I thought the 2sc1312 and 2sc1313 blameless but replacements have improved sound before.
     
  16. Spenser

    Spenser AK Subscriber Subscriber

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    Thanks, Mark. I appreciate the feedback.

    Report 4: I'm finished with the Control Amplifier Board now. Replaced all electrolytic capacitors. Again found 2SA763's -- Q1, Q2 -- and 2SC1344's (not 2SC1312's), in the Q5-6 positions, so no transistor replacements.

    Next Moves: Equalizer Amplifier Board.

    Notes: Still running check-ups using DBT, and taking power supply voltage readings, after every five or six component replacements. Still all good. Also checking sound using tuner. Hearing noticeable improvement in sound quality. Wow. Fun.
     
    Last edited: Feb 10, 2018
  17. Spenser

    Spenser AK Subscriber Subscriber

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    Question: What's the story on these cute little guys? These were in the Control Amplifier Board, C1 and C2 positions, in line just before the first-transistor-bases in the Q1/Q3 and Q2/Q4 pairs. Pioneer Part# CSZA 010M 25 (1uF 25V), according to the service manual . Probably overkill but I I replaced with 1uF 50V longer-lead WIMA's set up high (wire insulation on the leads), on account of the tight fit between resistors.

    csza 010 M 25 02-10-18.jpg
     
    Last edited: Feb 10, 2018
  18. markthefixer

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

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    Sorry!! The control amp board gets new transistors (even the 1344's), it does have an effect that the power amp doesn't.
    That's why they're on the list.
    Something to do with the power amp feedback that compensates for deficiencies if there.

    The cute little guys, CSZA caps are tantalum caps - fine for power bypass (except for their disturbing tendency to fail as short circuits and start GLOWING), not so great as audio coupling caps.

    Wima's are GREAT for that CSZA circuit position.
     
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  19. Spenser

    Spenser AK Subscriber Subscriber

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    Thank you for advising DO recommend replace all transistors in control amplifier board. Thanks, too, for saying why do so there, and why not-necessarily in power amp board.

    I'll get that control amplifier board back out and do those transistors before moving on to the next.

    Sorry Another Question: does the recommendation to replace all transistors apply to the equalizer amp board, as well?

    Aha! So THAT is what the storied tantalum caps look like. Small, pretty to look at and benign. Lke a Coral Snake.
     
    Last edited: Feb 10, 2018
  20. markthefixer

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

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    All of the preamp (non-power amp) transistors will greatly benefit from replacement. The replacements are 30 + years of improved manufacturing technology.
    Of course new coupling capacitors are also needed to realize the benefits. Just a plain re-cap mainly does it - caps have gotten better as well, and "film caps" for the 0.1uf 1 uf range instead of using electrolytic caps are the icing on the cake. There are some important details about their construction that lets sound through very nicely indeed.

    But one has to draw the line somewhere, and generally it's at the power amp. Of course with the restoration work I do I tend to go further.
    BUT there ARE some transistors that are hard to get replacements for. In the "NSA" amps there are some infernally fast drivers that defy replacements (they run at over 100 megahertz) that it is best to keep as long as they are behaving themselves.

    The RE-supply of replacements is drying up - things just don't NEED the high voltage and high gain we use in our audio transistors so manufacturers don't have the sales volume of them to justify the costs of keeping those lines active. While I bought bags of 1000 for the price breaks way back when - all the new "recruits" to preservation are starting to run smack dab into not being able to get new trustworthy transistors.

    So if the power amp is working, just do the troublemakers, if the troublemakers have hurt the power amp, do the whole power amp when possible.

    People start to realize that all the hard work is GETTING TO the parts to replace them, so it makes sense to spend a few (and just a few) extra bucks and get it all over with before closing it up.
     
    Last edited: Feb 11, 2018

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