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Vintage Sony discman d-7 dead

I got my hands on a discman D-7, I like older toys, and its got the classic dead symtom. No nothing. Well, I got a steady 12 volts in, but everywhere I probe, even the power switch, 0v. nadda.

In the power regulator area, I got 12v going to a few select transistors, and I got 6 to 8 volts comming out of one, and different areas I got

1.2volts to zilch. Nothing getting to the power switch.

There is also a big silver box like thing that has leads soldered in the board around that area, Is this the voltage regulator box? Im thinking about cutting that away and finding out.

I took readings on those pins, got about 10 volts in from the b+ supply, and no other voltages elsewhere on the outputs.

Also, Does anyone have service info or schematics theyd like to send?

Reply to
Mike
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The silver box might be a dc to dc convertor. You could start by confirming the door close switch is ok. Next , if the function pcb is on top of the lid , i'd look for a break in the connector or flex pcb linking it to the main circuit board. I had a case once when the faulty component was simply a defective play switch. Jango

Reply to
jango2

it is a PWM dc-dc converter.

I tore into the box, and the outputs have 6.3v caps, so by that, im juding the ouput is +/- 5v.

one pin is hooked to ground, the top pin is negative of the set of caps, the other is on the positive. Just like you would setup a rail on a power amplifier.

The other side has 4 pins. One is VCC, I know that, The other I have no idea, but it goes through a resistor to the VCC of the PWM IC. So, Im assuming thats also VCC.

and there are 2 left, one I have no idea, it goes to the main cd micro. (standby enabel?) and the other one goes to the base of a transistor. So, i guess when it is held high, it switches on that transistor which maybe turns on the Dc-dc? well that transistor has a 25 marking on it, SMD, and it reads nearly open. same on the other 2 that are on the DC DC.

hmmm. I assume the standby circuits get power, and when you press play, it toggles those pins high on the DC dC, causing it to switch on, and provide power to the LCD and the rest of the circuits?

Also, i have no idea, but when you flip the power switch, does the LCD immidiatly come on? or not? does the LCD only come on when you press play?

I got nothing out of this player. I see VCC on my required pins, but no output. so the DC DC isnt runing, maybe because those SMD transistors inside the module are reading about1.5 to infinate drop. supposed to be .5 to .7??

Reply to
Mike

I fixed it. 2 bad transistors, the shunt regulator driver, and a STROBE switcher in the DC-DC box.

classic

about

and

Reply to
Mike

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