low voltage Classic

[bibilit]

Not lucky with Classic ABs.

I have a Classic at home, Logic board has been recaped and working great, but the AB is not delivering the proper voltages.

New caps in the usual area and new Optoisolator as well.

The 12 v is around 11.4 at best and the 5 v is around 4.5 v.

the screen is wobbling also, even when voltages are fine (managed to crank voltage for a test)

Any idea welcomed.

 

[bibilit]

Another one solved.

Here, The Analog board was the late model, 220 volts type.

Voltage at pin 6 of the TDA4605 was a bit low also, and PP1 was not able to crank the voltage high enough.

replaced both diodes DP4 and DP3 (1N4148), capacitors CP4 and CP5 (47 uf/25 volt and 1 uf/50 volt) and touched weldings around :







Both diodes were leaky, now PP1 can be adjusted.

So all in all those two diodes have a high failure rate.

 

[sigtau]

Wait a second, you're telling me that diodes can leak too?