Sony D50 - Won't power on

[ThePlague]

Hello all,

I just purchased a non working Sony D50 CD player. The person I got it from says it doesn't power on. I have to wait to confirm that as it has a euro plug. Just doing some checking I found that the fuses in the power adapter were fine and the voltage was set to 110. Someone has been inside it as there are screws missing and this worries me slightly. The only thing that seemed odd on the board was this bubbled white plastic. To me it looks like this chip overheated. Does anyone else have any opinions? The IC in question is the RF Amp/Signal Processor CX20109.

 

[mhedges]

Yeah that doesn't look good. You don't always see visible damage on ICs when they go bad. Actually I'd say usually you don't see anything amiss at all.

Is this the D50 Walkman?

 

[ThePlague]

Yeah that doesn't look good. You don't always see visible damage on ICs when they go bad. Actually I'd say usually you don't see anything amiss at all.

Is this the D50 Walkman?

It seems odd to me that this IC would have visibly failed as according to the schematic it is a ways down the chain from power. It is the D-50 "Discman" it doesn't have any Discman badging though.

 

[mhedges]

Yes Discman of course. Sorry!

I didn't realize they had surface mount tech in 82. I thought it wasn't seen until the late 80s.

Anyway good luck. Sorry I can't be of much help. A brief search seems to indicate that you have your work cut out for you.

 

[ThePlague]

Its definitely going to be a lot of work. I just learned that these older sony devices had the plug polarity reversed from today's standards. Since it has a euro plug, my guess is the person tried to a regular adapter and this caused the damage. The only question now is if it is possible to reverse the damage.

 

[mhedges]

If you mean the AC plug then it really shouldn't matter if it's reversed.

 

[ThePlague]

I mean the circular plug. Since it had the euro plug on the original power supply, the person probably just used a power adapter they found which has opposite polarity. Looking at the schematic, the chip in question along with a servo motor control IC aren't after the voltage regulators. They get power straight from the DC-DC converter. I'm hoping the voltage regulators stopped damage to all of the 3.3/5.0 logic.

 

[mhedges]

I would think a simple diode in the path would protect the circuit from a reversed polarity AC adapter.

 

[ThePlague]

One would think, but in the schematic the IC that I posted above comes right off the DC-DC converter. So if it took a hit, I'd imagine the other two ICs are the same.