Hi, i recently got a sony wm-7 walkman in very neat condition, and replaced its belt, and it's having some weird issues, see video. When i open cassette door and click play, the motor sounds loud and then the walkman stops responding to any button. If anyone have idea then please suggest, it's a pretty thing to restore.
Hello ! I think I know what the problem is with your WM-7. You have probably put a high-impedance load on the heaphone output (I see that there is something plugged in) that is triggering the remote control circuitry. For example, the input impedance of an external amplifier is clearly too high and will for sure trigger the remote control circuit. I tried mine with 16ohm, 32ohm and 50hm headphones and works fine, so I would guess that probably anything below 200 ohms or so would work. Try running it with nothing plugged into the headphone socket and see if the problem disappears.
Make sure that the belt routing is correct. I will attach a picture from the service manual with the correct routing. There could be one of 3 things that cause this problem: 1. The remote control circuit (since it does it with heaphones not plugged in, I would assume this is not the problem, for now; although it could be some dodgy contact inside the connector itself, which loads the output with 33ohm resistors when nothing is plugged in) 2. The mode switch is dirty and the microcontroller does not detect that the mechanism is in fully loaded position (I opened mine when I serviced it, but it wasn't dirty, so I would say it's unlikely to be this). 3. The table reel sensor does not detect the table reel rotating or it detects the wrong one rotating (example: the mode switch is in forward position, but the reverse reel is rotating). This could indicate either a belt routing issue or a problem with the sensor itself. I would start with checking the belt routing first, since you say the problem appeared after replacing the belt, so that's the most likely cause now.
Many thanks for nice information, i will definitely check the belt first. I will also clean all contacts with electronics contact cleaner to make sure every switch is clean. I hope it will fix the issue. Otherwise i have to let it go for parts or repair. As the overall cosmetics are Excellent, and it seems like very very less used. And some professional can easily fix it.
WM-7 is very sophisticated. No ordinary construction. For example there is a small contact switch behind the PCB. This switch is normal open until you close the door. Therefore the walkman is not suppose to power on or play if you leave the door open. You said you opened the door and clicked play. This sounds to me that the small contact switch on the PCB was incorrectly fitted or damaged. "motor sounds loud" could mean gears grinding. That would be another story. Again WM-7 restoration could be a real challenge.
...besides all clues above, mke sure you have the right belt - not size only. the wm-7 needs the perfect belt, same as f.ex. wm10rv/40
I have missed that detail when responding. The door latch can be manually activated with the door opened, but I don't know if that is what @groundlessfears did. Now that I'm thinking more about it, "motor sounds loud" can also mean the belt has slipped of the motor pulley, so the motor is freespinning (it will sound louder without a belt in place). As @autoreverser mentioned, the belt must be the right one. I will put a link for reference: https://www.ebay.com/itm/131772035077 There is also something else I like to mention, discovered this when lubricating mine: if the motor is spinning the wrong way (wires soldered backwards on the PCB), the belt will slip immediately off the motor pulley. I am considering this as a possibility because the motor wires need to be desoldered when removing the PCB. The WHITE wire is the positive and RED wire is negative, contrary to intuition. They are marked on the PCB W and R. I discovered this while I powered on the motor with a lab power supply and put the positive on red wire: belt slipped immediately. Initially I didn't understand why that happened, but I figured it out later on when putting the PCB back and problem was gone.
Even if I arrive late ... you already have this information ... I placed this photo for further clarity ... Pay attention to the position of the belt on the engine ... it is very easy to misplace the position
