The Sony CFD-S05 unit will not power up

"I troublehot (and fixed!) that very problem just the other day. You can get schematics for that unit at electrotanya. The symptom you describe happens when the main voltage does not turn on (quickly enough) when the unit leaves standby mode. The start-up process is actually quite complex (possibly it is meant as short-circuit protection): Power is turned on by a high level on the base of Q951. The high level there turns on the transistor. The first thing that happens is that the main power rails (+9V, +6.2V and +3.3V) are pre-charged through the diodes D951 and D952 (a dual diode). The total current available to pre-charge the power rails is limit by R950-R953 to around 20mA. Only when all of the power rails are charged to around 1.0V, the emitter voltage at Q951 is high enough to turn on Q953 which drivers the main power switch transistor Q952. The +6.2V and +3.3V regulators are powered from the output of Q952 and thus also turn on after Q952 turns on.

In the case of my broken unit, the pre-charge didn’t manage to bring up the +9V rail above 100mV (which can be measured for example at pin 1 of IC302). This was caused by excessive leakage current in C329. I temporarily “fixed” it by accidentally shorting the switched +9V line to the unswitched +9V line, which slightly reformed the capacitor. The permanent fix is to replace the cap."

I had the same problem and found C953 had gone short circuit, replaced this and it now powers up OK.

cndwilson sounds like you have an issue with the power circuitry on the mainboard. Disassemble it and check for any burned/leaking or domed looking caps. Post some images of your board with your question. Use this guidefor that. That way we can see what you see. Use these guides to work on your Sony

"Hi @transform2020,

Asking questions when you don’t know is never dumb, not asking questions when you don’t know, is.

Here’s a link that may help.

Just select the value of the capacitor C329 = 470uF 16V, can’t see C953 value shown in answers above, but it should be marked on the capacitor itself.

Alternatively, there are electronics parts suppliers in Vancouver.

Just search for electronics parts Vancouver Canada to get results. Contact them and ask if they have the required components in stock.

Ebay also has them but you mostly have to order in minimum quantities (mostly >5) and there may be shipping delays as the less expensive ones are shipped out of China"

"I am fixing a unit with the identical problem. After some troubleshooting and replacing the two above stated capacitors, the unit continued to do the same. (Turn on very briefly)

I should have gone with my first instincts which was a fault in the capacitor at C950 !!

4700uF @ 16V

(I replaced it with a 25V)

Once this cap was replaced, the unit functioned as it should."

"I think with this CD player any of the electrolytic caps are suspect. As I remember there are several power supply lines of different voltages in this unit. When troubleshooting I found it easiest to disconnect all the supply lines and then check them one by one to see which one is shorted. When you find the shorted supply line start removing capacitors on that line until the short goes away. Once the short disappears you found the shorted capacitor.

Alternatively you could just replace all the electrolytics. It’s likely just a matter of time until they all short out."