A LED mod for the SX-3900, and rebuild for Reliability

Discussion in 'Pioneer Audio' started by zebulon1, Jun 5, 2017.

  1. zebulon1

    zebulon1 Into Phase Linear's lately Subscriber

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    I thought I would post this thread and add to the database images of the set with the LED mod in progress.
    So far I have the lamps exposed and waiting on the Mouser order.

    One other thing: The entire dial, back lighting harness is missing. wire, sockets and lamps all gone. A guy horsed in two fuse type lamps and hot glued the lamps on either side of the light diffuser.

    If this thread rings a bell please post your images or thoughts.

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  2. zebulon1

    zebulon1 Into Phase Linear's lately Subscriber

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    The original dial defuse'r lamp holders are missing so I had seen Marks replacement holder and will use that with a set of wedge LED's from eBay.
    Images of the set as received:
    Ecky

    [​IMG]

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  3. zebulon1

    zebulon1 Into Phase Linear's lately Subscriber

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    I received the LED's ordered from Dave.
    The "White, 4mm wire lead diffused LED's with in-line circuitry" for all the selector switching indication. They fit like a glove.
    So far:

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  4. zebulon1

    zebulon1 Into Phase Linear's lately Subscriber

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    Indicators are done. Took about 1.5 hours to complete (9 total).
    The "Stereo" indicator will light in both polarities but works like it should in one way. I used jumpers and tested the indicators before connecting the leads permanently.
    Waiting on the Dial lamp sockets. I see their here in town, hopefully tomorrow I can finish this job.

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    Last edited: Jun 14, 2017
  5. zebulon1

    zebulon1 Into Phase Linear's lately Subscriber

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    I finished the mod this morning and it really made the set pop.
    The sockets from Mouser fit perfectly. The only issue is that the pointer string runs close to the socket wiring. I secured the socket harness to the defuser so the two do not become tangled or damaged by the tuning operation.
    The dial lighting is from the "Light Blue" wedge LED's.

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  6. Drayhazel

    Drayhazel New Member

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    That looks awesome !!
     
  7. zebulon1

    zebulon1 Into Phase Linear's lately Subscriber

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    I checked out the settings for Dennis and cleaned it up a bit.

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    sawdust, baco99 and Drayhazel like this.
  8. Drayhazel

    Drayhazel New Member

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    Looks awesome !!!
     
  9. zebulon1

    zebulon1 Into Phase Linear's lately Subscriber

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    After finishing the lighting I was having reservations about the sets condition. The power supply was showing signs of stress and the tone seemed muddy in both the Bass and Treble.
    Mentioning it to the owner Dennis only after some thought. Work was piling up with equipment from other clients and did I have the extra time to sort the receiver out? There was no decision really, it needed to be done. Dennis gave the go ahead and time I needed.
    Here's some images of the set in work:
    I thought I would add to the discussion for others working on these SX-3800 and 3900's, very similar in build.

    Below is the tone and amp boards. It's not the easiest set to work. Getting the boards out requires removing the heatsink and outputs, loosening up the harness from the other boards and removing the mounting screws from the Power Supply. This allows access to the power supply and tone control boards. The trick is to de-solder the lower AC and ground leads from the PS board.
    Remember to secure the dial string from unraveling from the VC pulley. I use a rubber band.

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    The power supply is toasted and had a previous repair, noted by a non Pioneer pass transistor.

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    The mounted transistors thermal paste was powder and the replacement pass transistor had nothing, no paste at all.
    Below are the drivers for the left Amp.


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    Completed tone board:

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    Attached Files:

    Last edited: Jul 17, 2017
  10. zebulon1

    zebulon1 Into Phase Linear's lately Subscriber

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    I use the modern sill pads for the outputs. I feel they benefit from the pads over the mica/paste. The outputs get really hot on these NSA amps and the sill pads will hold up to the abuse.
    I cut the pads from a sheet of material .007 inch or .19mm.

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    Some images of the before PS:

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  11. Awesomeaudio

    Awesomeaudio AK Subscriber Subscriber

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    Pardon my off topic note here Zeb.
    I don't recall hearing about these "Sil Pads" in place of the Micas. Google to the rescue !
    Here's what I found and interesting too.

    Sil-Pad� is a thermally-conductive interface material developed for the electronics industry. This flexible silicone material is designed to conduct heat away from discrete components or circuit board assemblies into a heat sink, heat spreader, or equipment chassis.

    Sil-Pad� 400 is a composite of silicone rubber and fiberglass. The material is specially formulated for use as a thermally conductive insulator. The primary use for Sil-Pad� 400 is to electrically isolate power sources from heat sinks.

    Sil-Pad� 400 has excellent mechanical and physical characteristics. Surfaces are pliable and allow complete surface contact with excellent heat dissipation. Sil-Pad� 400 actually improves its thermal resistance with age. The reinforcing fiberglass provides excellent cut-through resistance. Sil-Pad� 400 is non-toxic and resists damage from cleaning agents.

    Features:
    - Excellent thermal performance
    - Eliminates the mess of grease
    - More durable than mica
    - Flame retardant
     
  12. zebulon1

    zebulon1 Into Phase Linear's lately Subscriber

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    That's it.
    I'm slowly moving away from the paste.
     

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