Satellite receiver - no +5 V SB

[Khron]

Re: Satellite receiver - no +5 V SB

Are the output diodes and caps ok as well?

[Behemot]

Re: Satellite receiver - no +5 V SB

Some caps were replaced for crapxon but it is OK for the test, no diode seems to be shorted.

[kasfamily]

Re: Satellite receiver - no +5 V SB

Check R25

[Agent24]

Re: Satellite receiver - no +5 V SB

Have you tried Google for images of this same PSU\Tuner? Maybe you can find a photo that shows the original Opto.

[Behemot]

Re: Satellite receiver - no +5 V SB

I think I've tried looking after a replacement one and found nothing at all. One of the devices meant to be thrown away after 2 years and bought a new one...

[Behemot]

Re: Satellite receiver - no +5 V SB

Check R25

It is OK at 2,021 MΩ.

[stj]

Re: Satellite receiver - no +5 V SB

check the primary rectifier diodes - and i mean properly, not just for shorts.
then put another 400v smoothing cap on just for a test.

i'm still not happy about that ripple in the early part of the thread.

[Behemot]

Re: Satellite receiver - no +5 V SB

What else can I test? I got the right DC voltage on the input cap so they all must be working and not shorted.

As for the ripple, I have yet to measure it grounded with O-scope ground…

[stj]

Re: Satellite receiver - no +5 V SB

if a diode is open, you will still get the voltage,
but because it is half-wave rectified for half the cycle, the ripple is much worse.
and the cap has been calculated to kill full-wave ripple - not half-wave.

do a diode-test on the diodes for voltdrop etc.

[Behemot]

Re: Satellite receiver - no +5 V SB

I did, I always test diodes with diode tester, all of them had usual 350 or so.