Beko 30WLB500S - Sound, no picture

[PlainBill]

Re: Beko 30WLB500S - Sound, no picture

Ok, did a few tests.

On the bridge rectifier BD1, I was getting about 0.5 as normal (using guide from here), but when I reversed the leads to see if I see a high reading, I was getting the same 0.5 (the BR on the good board was showing about 0.5 and high as expected with the various combinations).

The D1 diode (BYV28-600) close to it was reading 0 both ways (and fell apart when I desoldered it, and I think I can see the fracture line on the original photo). I was seeing about 0.37 and high on the corresponding diode on the good board; is this possibly marginal?

However, when D1 was taken off the board, I retested the bridge rectifier. The AC to + tests were reading 0.5, reversed they went up to 0.8. The AC to - tests gave similar results, 0.5 normal direction, 0.8 reversed.

D1 is (normally) connected between points 1 and 4 of the bridge rectifier.

Does the bridge rectifier sound like it's ok?

Would the bad diode at D1 be causing the blown fuses? Or do I need to look at any other components?

I would remove the bridge rectifier and test it out of circuit. Unless you have a way of increasing the voltage slowly, you don't want to plug it in to see if you've found the problem.

PlainBill

[tmcw]

Re: Beko 30WLB500S - Sound, no picture

I would remove the bridge rectifier and test it out of circuit. Unless you have a way of increasing the voltage slowly, you don't want to plug it in to see if you've found the problem.

PlainBill

Ok, have done that, and it seems to be ok, readings are about 0.460-0.480 one way, overloading the meter the other way. I assume that's ok?

Anything else around there that I should test?

[PlainBill]

Re: Beko 30WLB500S - Sound, no picture

Ok, have done that, and it seems to be ok, readings are about 0.460-0.480 one way, overloading the meter the other way. I assume that's ok?

Anything else around there that I should test?

I would check D3, Q1, Q4 and the transistor on the other side of the heat sink from Q4 (Q9?). If everything checks out, while waiting for the fuse to arrive, I'd connect a 120 volt incandescent light bulb (60 or 100 watt) as a replacement for the fuse. When power is applied the light bulb should glow brightly for a few seconds, then glow dimly and you should have voltage on the standby output of the power supply.

PlainBill