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 11, 2018

     

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  2. Spenser

    Spenser AK Subscriber Subscriber

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    Report 5: Replaced transistors in Control Amplifier Board and all electrolytic capacitors and transisitors in the Equalizer Amplifier Board. Sounds fantastic. Wow.

    Next Moves: recap and carefully clean tuner. Still have to circle back to the protection circuit and replace relay. Still have to do lamps. Mouser and Wojnarowski orders should arrive soon. Couple trim pots coming, too. Originally ordered wrong resistance for VR3,4.
     
  3. Spenser

    Spenser AK Subscriber Subscriber

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    Report 6: Tuner Board recap completed. Replaced 15 capacitors and two transistors. Does not seem to have thrown off alignment, at least inasmuch as still tuning FM station it has been on throughout. Check out these Nichicon film caps. Used Wima elsewhere but another member had these on his list for the tuner so I thought I would give them a try. Whoa baby. Fun.

    Note: First restoration with a lazy susan. Good grief I don't know how I've lived without one. This project would have been tremendously more difficult had it not been for this simple tool. The view of this board of course is with the receiver standing on end transformer side down.

    Humongo Lollipops. (Nichicon QYX Series Film Capacitors)
    Tuner Board Pioneer SX-737 02-13-18.jpg
     
    Last edited: Feb 13, 2018
  4. loweran

    loweran AK Subscriber Subscriber

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    Good progress!
     
  5. Spenser

    Spenser AK Subscriber Subscriber

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    Thanks Loweran man for additional words of encouragement!

    Note: the new relay didn't want to fit into the old case; and I didn't want to force it (not sure it would have been possible to, really); so I went with the protocol Echowars came up with if you follow the link back on Post #21.

    I found I didn't need the washers between the standoffs and the chassis (you may or may not); DID use washers on either side of the tabs for a nice fit and to avoid stressing the plastic; the original screws work here to mount the tabs to the standoffs.

    The standoff threads in my case were not a perfect thread-match for the chassis holes but close enough; gently cranked them in there and the holes self-tapped-adjusted; lock tight meh didn't.

    Here is the Mouser part number for the standoffs. The Digikey part number is in the Echowars post (basically the same part number). Remember you will need 4 standoffs. The standoffs DO cost a couple bucks but what a nice result.

    534-24315
     
    Last edited: Feb 14, 2018
  6. larryderouin

    larryderouin Turn it UP, POP? PLLUUEEEZZZZZEE Subscriber

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    Sounds like you've got the Gremlins :whip:on the run. The rest of it is fairly easy and shouldn't take more than 1 evening (if you stay up until 4am on a workday):D
     

     

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  7. Spenser

    Spenser AK Subscriber Subscriber

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    Thank you, Larry. I got a good chuckle out of your message when I read it earlier today. Been plugging away.

    Before I secure the boards and tidy up the wires, let me run these power supply voltages up the flag pole here; and also ask if there is anything else that should be addresssed before buttoning her up?

    Power Supply Voltages
    Pin Spec / Actual

    14 35V / 34.8V
    13 -13 / -12.8
    19 13 / 13
    7 -38 / -38.7
    9 37 / 37.3
    10 -37 / -37.2

    All I have left to do is check and possibly clean the variable tuning capacitors ground leaf contacts to the shaft all the way across with toothpick-applied deoxit, and spray the tuning capacitors down with CRC QD non residue.

    The stereo indicator lamp issue I was having before I think was due to signal interference from my lab bench LED strip lighting. Sometimes I forget to turn it off; wreaks havoc with radio signals.

    Which reminds me to mention, Messr. Wojnarowski sent me warm white LED fuse lamps instead of incandescent, so that is what went in. He must've been doing that Spok Vulcan mind thing again. Knew deep down I wanted to try these out. They look good.
     
    Last edited: Feb 15, 2018
  8. larryderouin

    larryderouin Turn it UP, POP? PLLUUEEEZZZZZEE Subscriber

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    Voltages look good. There's always going to be a bit of variation based on todays voltages vs. 1974-1976. If they are within 10% give it a kick in the pants and let'er rip.
     
  9. Spenser

    Spenser AK Subscriber Subscriber

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    Thanks, Larry. Thanks everyone. This receiver sounds amazing. Looks amazing, too. Really a pretty receiver.

    I very much appreciate all of everyone's kind advice and support. Had a blast you guys. Cannot thank you enough.

    I have several other pieces in my queue. I think, though, I want to dedicate some time to Malvino, Horowitz and Hall and the ARRL Handbook first, alongside the 737 schematic, before rewarding myself with more substitution list and solder monkey time.

    I will be back though before long. You can be sure.

    Very truly yours.

    -Matt
     

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