Trying to fix a Sony Discman D-50 - Stuck at troubleshooting

kaosun

1: Door switch and laser switch measured working.
2: 9V input working, 5V for CPU working.
3: Pressing PLAY, a POWER ON signal will be sent to power DC_DC unit. If the unit works flawlessly, it outputs +5V, -5V and controlled 9V.
4: You can download the service manual from out website to have the detail of the DC_DC unit, it will help you replacing all burnt components.
5: When the DC-DC unit is fixed, directly apply 9V, GND to it, connect a 1K resistor between 9V and ON/OFF terminal, you can measure +5V, -5V and 9V from each terminals of the unit. After that, restore the unit back to the D50 to test reading.

kaosun

It seems it's less likely to be repaired due to PCB  burnt.

electronomad

Hi. Sorry if it was asked before.
I'm currently in possession of D-5 & D-50 with similar problems. Both have failed IC802 and CP-301 (DC-DC conv)
CP-301 on D-5: P/N 1-464-378-14. Pins 2 & 6 are short (Q3 B985 is short, adjacent inductance overheats)
CP-301 on D-50: P/N 1-464-378-13. Pin 2 is sort Q3 - diffrent one - short & blown and can't be id'd and smd diode (?) beside it is also short & blown.
Strangely but none of the D-5 service manuals in circulation has details about CP-301.
Could you please share some info about it like schematics, active components?