Hello people of S2G, I have a Sony WM-FX 999 from 1993, it's a high-end model with a dual head mechanism. The radio works, but the cassette belts are bad. I'm new to this breed of Walkmans, as I've only dealt with cheapo, botl Panasonic models. I have two questions: 1. Is this model easy to work on compared with my cheap Panasonics? 2. If not, are there any repair shops in the california bay area? I'm living temporarily in San Francisco and I would like to get it repaired if I don't have the means to do it myself. Thanks. Theo.
I don't have that model, most of mine are before 1988 but I'd pop off the screws and check it out. There's a chance that it requires some desoldering but it might be a nice easy swap. Repair shops are getting harder to find, there's a thread on the site somewhere with guys doing this work. I've had bad luck in the Midwest and try to do a few myself every once in a great while. As long as they don't have ripped ribbon cables I've done ok.
Belt replacement is easy on this model, but if the single pinch roller between the 2 heads is bad/dented, it's not worth doing, unless you can find a new pinch roller. (This is one of 2-3 dual head Walkmans Sony made).
I recently bought this model, it was sold as "no power" which I assumed was a battery corrosion / connection issue. However the power led flashes on briefly and it beeps and then switches off. Sometimes the LCD screen comes on with random characters. The front casing has a small dent near to the screen but there is no visible damage on the main circuit board. I took it apart and discovered that if I put a bit of pressure over the ribbon connector it works fine but turns off as soon as I remove my finger. I can't see any cracks in the board, maybe it is a dry joint.
Looking at the block diagram in the service manual, there are quite a few things that need to work properly for this device to power on. There are 2 main ICs (IC701 and IC501) that control the operation of this unit and these 2 communicate with each other through a serial bus. Given IC501 also communicates with the remote control, I would assume the communication between this IC and the main microcontroller is needed for proper operation. This IC501 is also what drives the LCD. The random characters appearing on LCD can be either from corrupt data on the serial bus or from the zebra strip underneath the LCD. However I would ignore the LCD for the moment, as given the controller is inside IC501, a connection problem with the zebra strip will not be "seen" by IC501. Apart from this there is a battery detect IC (IC704 - it's the SOP8 package under the LCD) which I assume has to also generate the proper signals for the microcontroller to start. Then there the reset IC (IC702): if the microcontroller reset pin is kept low (it should be high during operation), the firmware will never run. Where you point out that pressing restores functionality are a lot of vias (also notice a test pad SCLK1 in that area). You may have a problem with a cold solder joint on IC501 or a broken via. But you need to narrow the area down a bit more and eventually look under a magnifiying glass for any obvious damage. The flex itself looks good and at least the radio part should work perfectly fine without that solenoid connected. As a sidenote, it's interesting how the main gear is made on this unit with the very long teeth. Probably to create some cushion in order to reduce the wow&flutter caused by gear teeth engagement. Very interesting !
