WM10 Powered up for ⅓ of a second, then died

Hello everyone, I hope someone will know how to solve this:

I have this WM10 which used to work just fine. I changed the belt a few years ago and was playing nice.

I put a battery today, plugged the phones and pushed the play button: the red LED shined, the motor hummed and the tape moved... at least for less than a second and the thing died.

I wiggled the earphone plug, checked the battery with a multimeter, cleaned both the battery and its connectors in the Walkman and still nothing.

I opened it up hoping the little copper switches for PLAY/FFW/REW were dirty, or something... Nothing.

This is what I've done, so far:

The PCB does get voltage, I measured 1.5 at diferent points. I know it should be higher than 1.5 at some points, but I don't know where to measure that voltage.

I used one of the multimeter probes to touch the two pairs of copper switches hoping to "jump" them in case they were not doing their job. Still nothing, the PLAY button was presssed when I tried jumping the switches. I kept wiggling the battery and the plug hoping something was just gummed up and the wiggling would clean it. Nothing.

I counted about 6 or 7 catalithic capacitors. Could they be the ones to blame? They're 41 years old!!...

This Walkman has no telltale sign whatsoever of acid leaks. It's clean in the battery compartment and the contacts are shiny, not corrosion AT ALL. Also, the PCB shows no signs of acid contact or corrosion. This thing was working fine and I stored in a sealed bag with a packet of silica gel inside to absorb any moisture.

What do you suggest I do next?

The dirt you see in the red squares is not corrosion, its just a thin foam sticker that degraded and left that goo there, I guess it isolates the aluminium case from the screw that goes there. I will put a new something there after I repair this beauty.

Please help!!

 

Thanks, I will look into that... But I was completely unaware these had any door-activated switches

 

Does the motor keep turning without the belt? Looks like it needs to work hard and draws to much current and then it will cease like instantly, had this on a WM60, even with full battery it would stop in a second. So to me this looks like to be a friction problem somewhere, you said you have stored it for a while so grease can become hard and create friction on turning parts.

edit: what you can also check, inside the the take up reel there is a switch (S901) on the axle. If this is dirty or doesn't make good contact it will not play.

 

Will look into the take up reel switch, thanks.

I haven't taken the belt off, but I was able to spin the motor pulley with the multimeter probe and it it didn't seem stuck, I also turned the capstan pulley with my finger and didn't seem to oppose either. I'll take the belt off and spin the motor and look for friction.

 

Hi, try checking the power outlet...as in this link

https://www.stereo2go.com/forums/threads/sony-wm-20-repair-restored.5573/page-2

 

I'll take a look there, thanks.

 

circled in red, clean the power activation switches, i used to wrap a toothpick in cotton from a t-tip to clean them easier without risk of bending them
second what you have circled would be a ground point, clean the gunk off the top and remove the screw to clean anything that might be blocking connection with the board contact
chances are its just the switches that need cleaning off though

also try cleaning out the headphone jack, not sure if the same on the wm-10, but in the f10 if it doesnt detect headphones itll power off. could be yours is dirty

 

Yes, there's a switch in the headphones jack in the WM10 too, I'll test it with a multimeter to see if it's closing the circuit when the plug is in.

The leaf contacts were cleaned right after I opened it. They were my primary suspect, but no, it wasn't that.

Thanks.

 

@Sergio Salinas
Here a picture of S901 on the take up axle, also a pic of the cracked gear on the take up reel. Is yours still in one piece? If not it could jam the mech and show the symptons your having. When its jammed the motor can't get the mech moving, draws to much current and shuts down.
Or the S901 is not sensing movement of the take up reel and shuts down. So cracked gear could cause all of this. My F15 sometimes would play with clicking untill the crack jammed itself on the gear, S901 senses no movement of take up and shuts down....worth checking.
Pic are from my WM-F15 which uses the same mech as the WM-10.

 

Thanks, when I press the play button it's completely dead. The issues you mention would at least let the LED come on for a split second and I would be able to notice the motor trying... but there's nothing at all, not with the play button, or any of the other too. The thing is completely dead.

 

-assuming you tried previous stuff, cleaning gunk off ground and switches, plus cleaning aux jack + reflowing it just in case
capacitors could be the cause, they are known to die on these and be near impossible to replace (except for smds, but i didnt get far in testing since i didnt have the tools when i tried smd recap years ago)
-bad caps CAN cause no power, but id use a tester like the TC1 to verify they are good/bad before going gung-ho in trying to recap it
try testing continuity between the power switch contacts and board, slim chance its actually bad but cant hurt to check they are working correctly
test continuity between the left channel of the headphone jack and the power contact, inc picture of exact contacts to test with headphones hooked up. if its bad or dirty it would cut power to the entire player (in your case, would make sense if this is the issue)
-if bad you could prolly just bridge contacts with some ((insulated)) wire- so you dont accidentally bridge channel contacts or ground



if the reel contacts are dirty or otherwise messed up, it might cut power to the entire player since it has 3v running through it at all times for the sensor to function, might try cleaning it, but maybe im misinterpreting the manual here
-if it works how i think, without that power present itll cut power as thats how the auto stop functions. so if dirty- no power at all since there was never power present for it to start (is what im thinking)
--nvm after looking back this is probably wrong, disregard


just what i happened to see going through the manual, still working on my circuit reading skills so take a bit of it with a grain of salt

 

Thanks, this will be very helpful.

Do you have a PDF file of the service manual?

 

ya its up on walkman land, heres a link - https://walkman.land/document/184/Sony_WM-10_-_Service_Manualpdf

 

Thanks a lot!! ✌