[SOLVED] Oscilloscope Philips PM3302

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newtonsrl said:
IThe voltages, starting from pin 1 should be:
1) GND
2) +5V
3) -12V
4) +70V
5) +12V
6) AMP (i don't know what means)

and I measure:
1) 2.155V
2) 12.07V
3) 4.18V
4) -12.06V
5) 4.92V
6) 0V
Click to expand...

I agree with E-design's suggestion (post #16). Your first list (pins 1 through 6) is a mirror image of the second list (pins 6 through 1). Only your +70V pin gives you wrong reading (item 3 in second list). That disagrees with spec. I don't know what 'AMP' should be. All your other readings are a close match.
 

Pointing the negative of multimeter on the chassis, on C1005 I have -106V at -pole and +3.46V at the positive pole of the capacitor.

- - - Updated - - -

Found the problem!!!
The schematic shows T1006 as TIP47, but on the board there is BUX87.
I bought TIP47, and looking the datasheet this has reversed pin order!!! I've inverted the TIP47 and finally I got +70V and +45V!!!
Now I must reassemble everything and test it...
 

Here is a quick simulation to show what voltages to expect in the circuit when operating normally.
 

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  • 70V_reg.png
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Solved!! It works!!!
I'm happy like a child on Christmas Eve!!!!
 

Good for you! Luckily, it wasn't such a big problem to solve.
 

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