Sony PSX70 Auto cue issues

Discussion in 'Turntables' started by boostedb18, Feb 13, 2018.

  1. boostedb18

    boostedb18 Active Member

    Messages:
    237
    HI guys,

    Just picked up this PSX75. It is in amazing shape, from the original owner. While i was looking at it the auto function stopped working. The tonearm moves to almost center then returns. I suspect the LEDs, However if no record is on the platter the tonearm travels to just the edge of the platter and returns. Any ideas?
     
    Last edited: Feb 14, 2018 at 12:50 AM
  2. Harolda

    Harolda Active Member

    Messages:
    426
    Location:
    Netherlands
    The record detection system seems to work.
    There can be various causes for this:
    1) power supply voltages not up to spec (old electrolytics) in the power supply
    2) the trimmer for the drop point adjustment might have corrosion so the value is off
    3) failure of the main control ic
     
  3. boostedb18

    boostedb18 Active Member

    Messages:
    237
    Thanks Harolda. Starting to suspect its the IC. The tonearm now sometimes goes all the way to the center and sometimes gets to the edge of the record and pulsates . If i use the arm transport and cue myself the auto return doesnt work..

    I think i know the answer. But what are the chances of finding a working IC to have copied? Has anyone tried this? Side note I have a nicely working PSX600 Would there be a similar IC in there that i could copy?

    This is who i would use,
    http://www.advin.com/IC-Programming-Services.htm
     
  4. Harolda

    Harolda Active Member

    Messages:
    426
    Location:
    Netherlands
    I would check the power support voltages first, especially the voltages supplied to the IC’s. if these are off then the main controle IC or otter IC’s will go haywire!
    For my ps-b80 that was a simple solution to a lot of issues. Voltages where off due to bad electrolytics in the power supply. I changed the caps and verified the voltages where correct.

    After that I gradually replaced other electrolytics and trimmer pots step by step. Replacing the trimmer pots is much more complex, because afterwards you have to perform all adjustments iteratively.

    So check power supply voltages first and then decide what to do next
     
  5. boostedb18

    boostedb18 Active Member

    Messages:
    237
    This board it a bit more complicated then the last one I recapped. Should I start with c101 and c102? Or are there caps actually in the power supply?

    [​IMG]
     
  6. Harolda

    Harolda Active Member

    Messages:
    426
    Location:
    Netherlands
    Don’t just start recapping. Get yourself a service manual and try to understand the circuit at least to the point to verify the voltages.
     
  7. boostedb18

    boostedb18 Active Member

    Messages:
    237
    too late :) I recapped it. Now the tonearm always moves to the center and stops does not cue. before the recap it would sometimes move to almost the center or sometimes the edge of the record and pulsate. . Just noticed the tower lamp is out. Not sure if it was the whole time or not. is that now the last piece of the puzzle?


    Just ordered these.
    https://www.ebay.com/itm/5-x-8V-50mA-Birne-Lampe-Miniature-Lamp-Bulb-T1-1-4-T1-25-4mm/112399276597?ssPageName=STRK:MEBIDX:IT&_trksid=p2057872.m2749.l2649

    Edit. It now cues when you first turn it on. did it 3 times in a row, auto return still not functioning
     
    Last edited: Feb 17, 2018 at 1:08 PM
  8. Harolda

    Harolda Active Member

    Messages:
    426
    Location:
    Netherlands
    Again check voltages!

    The picture you added already shows where you can measure the +5V rail (just above C101). That 5V is the power supply for all IC's.
     

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