Hi everyone , I just got this Sony Walkman wm 24 and is in pretty rough shape, the main problem is That there is no sound only buzzing noise, the cables connecting to the head looks fine and there is continuity, I think the problem is on the pcb how can I check where is the problem? If touch the point where the cables coming from the head connect to the pcb with a screwdriver normally you hear a loud noise coming to the headphones, but with this the static doesn’t change. Thank you so much! Maybe the big expert @Valentin can help me
First thing I would check is power getting to the preamp and Dolby IC. The power amp is powered directly from 3V line, but preamp and Dolby are powered from a regulator (Q301, Q302). So check if you have 2.5V on the collector of Q301. If you do, check if power and ground is actually getting to the preamp and Dolby. Service manual is available here: https://ia600401.us.archive.org/8/items/wm-14-24-25/wm-14.pdf
I do basic repairs but always start with the headphone jack, they get corrosion or the metal contacts/solder inside breaks, sometimes the hairline solder breaks are hard to see. Good luck!
Hi! Thank you , looks like there is power on the q301 and there is power coming to the Dolby chip, but checking the chip there is power only where I put the purple arrows, all the other pins show 0 volts. How do I check ground?
Vcc is pin 12, while GND is pin 5 on the CX20085. Check the ground also, not just Vcc. You can do this either by measuring directly between pins 5 and 12 and see if you get the same 2.5V or check the resistance between pin 5 and main circuit ground. Resistance should be a low value and measurement is done with power off/batteries removed.
My multimeter is not very good, and it shows lover voltage then reality, checking pin 5 and 12 there is voltage , around 2v but I think is about right considering my multimeter, the value when checking resistance stay at 1 and if I check continuity between pin 5 and ground there is not.
Something doesn't add up. If you have 2V between pins 5 and 12, you should have continuity between pin 5 and circuit ground also. Fact voltage is lower may be normal if you're using NiMH cells.
