What capacitors to replace?

Question

Do it yourself

Brought in for repair. tuner Orton 4100Cl - does not start, the red light is on.
The problem is BP. At 12 V, the line gives out 11.5 V.
The capacitors do not look swollen, but I sin on them. How to identify a problem capacitor?
I am attaching the diagram of this PSU.

What do you advise?

Answer 1

won't start, red light is on.

There is not a single red light bulb visible in your diagram (except for the LED inside the optocoupler, but it is clearly not red). From this I conclude that the signal about troubles is not sent by the power supply unit, but by the device itself. And check it out.
However, it is also useful to check the PSU in autonomous operation by loading it, for example, with light bulbs of suitable (not excessive) power and voltage - in fact, this is what experienced repairmen do.

At 12 V lines, it outputs 11.5 V.

Feedback for voltage stabilization is only connected from the 3.3 volt output - it will be stabilized by the PSU, the rest will line up as it should, and this greatly depends on the correct load of this output.

Answer 2

Measure the ESR of the conder and you will get an answer;)