WM-EX508 totally no reaction

Discussion in 'Tech talk' started by bplanes, Aug 16, 2024.

  1. bplanes

    bplanes New Member

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    Hello. everyone,
    I just bought an ex508 in a quite good state - it seems new- but with its battery in nothing happen. no "beep" no engine noise...
    (hold button is off)

    before a deep investigation, do you have any clue about this symptom on this model?

    thank you by advance.
    Bertrand
     
  2. Cassette2go

    Cassette2go Well-Known Member

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    Did you clean the battery terminals with Emery cloth? To ensure a good electrical connection?
     
  3. bplanes

    bplanes New Member

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    Hello Cassette2go,
    thank you for reply and your help, yes contact are cleaned and battery is new...
    here are some pics to give you an idea of it's state...
    sincerely
     

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  4. Cassette2go

    Cassette2go Well-Known Member

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    I have a 508 and mine has green on the positive terminal so I got my drill and my little micro tiny wire brush and cleaned it 17238460567183197854519752129768.jpg
    I got one of my favorite rechargeable batteries which is charged. Put it in there and I've never tested this one but it's dead too. Doesn't do a darn thing 17238462788988833084373842987916.jpg
    But I'm not worried. I got lots of walkmans that don't do anything. 17238463632865338205409418737734.jpg
    Curious what did you pay for yours?
    1723846642440548775217737306934.jpg
    I tried a different battery. A green hqrp battery. It did this for a second or two and the motor ran as I can hear it but it was rumbling or something but didn't do anything else here. I'll show you the battery 17238467371137581613658165209613.jpg
    And now I'm going to get back to what I was doing which is the Sony cf1990 17238468133024686955100049660897.jpg
    To see about it just look under tech talk in boomboxes. Good day.
     
    Last edited: Aug 16, 2024
  5. bplanes

    bplanes New Member

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    hello. thank you for your pictures,
    I m glad to hear it finally gave you a sign of life! it could be the engine wich need lubrification or the old melted belt which lock the engine...
    by my side no sign still... I stay confident, better to have nothing at all than strange symptoms.

    i bought mine 25e in France... ' 85% of chance it will play a tape soon... need to find the reason (it's a great hobby to find it)

    if news of yours don't hesitate to let me know'.
    sincerely
     
  6. Valentin

    Valentin Well-Known Member

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    There are 2 things I would check:
    - is voltage actually getting to the PCB ?
    - does the tape in switch (S702) get closed when a cassette is in ?

    Even if the motor was to be seized (which is unlikely), the power LED should still turn on briefly.
    The fact walkman doesn't do anything at all suggests either there's no voltage or it doesn't "see" a tape inside (case in which the buttons won't do anything).

    You can download the service manual from here: https://elektrotanya.com/sony_wm-ex502_ex508.pdf/download.html
     
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  7. bplanes

    bplanes New Member

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    hello Valentin,

    sorry for this delay I was away from home lost in countryside...

    i just checked if electricity reach the PCB, and yes
    btw I opened the WM and even if it seems pretty new, I noticed a light dust (oxidation?) very easy to remove around the head zone...
    I cleaned the PCB in case of sorry circuit caused but this undifined dust with contact bomb...
    no reaction! so frustrating cause it looks in. a so good state...


    i ll check the switch you adviced me to check, I didn't know there were a tape in switch on this model (I have another working ex508 and as far as I remember without tape it can start...)

    thank you!
     
  8. bplanes

    bplanes New Member

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    @Valentin I didn't localize the. tape in switch, would you please help me to find it?

    merci by advance
     
  9. Valentin

    Valentin Well-Known Member

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    Look in the cassette compartment, has to be on the back near the record safety tab of the cassette.
    Usually there are 2 swtiches there: one to change the EQ from 120us to 70us and another for tape detection.
     
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  10. bplanes

    bplanes New Member

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    hello
    something new :
    I spent few minutes with my wm to try some manipulations... after a while wow! I heard the typical noise of an engine with its broken belt! (and characteristic beeps trough my head phones)

    after few attempts I found how to. make it work each time : press strongly both side of the wm ( right top) ... and press play, it starts...

    well pbly a wrong contact... any idea?

    thank you
     

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    Last edited: Sep 7, 2024
  11. Cassette2go

    Cassette2go Well-Known Member

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    Cold solder joint. Perhaps circuit board cracked. My thoughts
     
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  12. bplanes

    bplanes New Member

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    hello Master
    yes.. I ll check soon, I noticed something important, when play button is pressed and engine starts, I can release the pressure on the wm and it continues to turn (few sec until the 3 beeps and stop because of the broken belt)
    it means It could be a wrong contact on the buttons circuits... no?
     
  13. Valentin

    Valentin Well-Known Member

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    That area you press on is where the buttons PCB connects to the main board. This explains why you can realease the pressure and unit still runs.
    I think you have a cracked PCB. Problem is described here: https://www.mikrocontroller.net/topic/563519
     
  14. bplanes

    bplanes New Member

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    hello Again Valentin
    merci beaucoup

    I finally found the problem...
    The wm have been already repaired and during the operation they pbly forget to unsold the 2 points and or force it...ill try to repair

    btw i noticed a mysterious patch added to the pcb (next picture) no idea the reason..

    any idea?

    thank you ☀️
     

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  15. bplanes

    bplanes New Member

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    à Quick repair to test it with 2 new soldering, it works now..
     
  16. bplanes

    bplanes New Member

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    here is the picture
     

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  17. Valentin

    Valentin Well-Known Member

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    Looks factory to me, it's a bodge on an early revision of the PCB most likely.
    On later revisions they probably added those components on the main PCB.
     
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  18. bplanes

    bplanes New Member

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    ... yes you're right! that's probably, some kind of beta revision, obvious!

    waiting now for the new belt from fixyouaudio.com

    preparing for cleaning... and lubrification, I have clock oil for bearing, but no idea what kind of grease to use for mechanical parts I would be grateful if you can advice me.

    back with with some update when something new happen

    thx again


    .
     
  19. Cassette2go

    Cassette2go Well-Known Member

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    Very simply do not use grease at all. Only use oil and only use oil sparingly.
    In my opinion, Sony used grease so it would last longer, but it will also gum up and freeze up if you don't use it on a regular basis, whereas oil doesn't freeze up or gum up, over time of use.
     
  20. Valentin

    Valentin Well-Known Member

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    For all rotating parts shafts use watch oil, even if there was grease from the factory.
    Only part where you need to use grease in on top of the motor bushing, as indicated in the attached image.
    Levers and other mechanism parts usually don't need re-greasing, but use grease there also if you want to re-lubricate.

    White lithium grease is fine for this application.
     

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