Grundig 32 LXW 82-8600 DL (XLA194-03 PSU)

[Trevtron]

I was given this 2008 vintage set to "see if I can get it going again", I like a challenge.
Powering up gave a blue standby light and pressing the power (or channel-up) button dimmed the standby light but nothing else apart from a soft 'pop' from the loudspeakers after a few seconds. A second press of the standby button restored full brightness to the LED so I concluded there can't be much wrong.
Whipped the back off & couldn't see any obvious swollen cap's or burnt components (I checked the back of the PSU board too), so I powered it up again to check a few voltages.
The 12V supply came up when coming out of standby but the 24V rail lingered around 1.3V, even with the inverter board disconnected.
As an experiment, I tried 'jump-starting' it off an external 24V supply and after a flicker of the backlight the set came on, and continued running even after disconnecting the auxiliary supply. Even switching the set to standby and back on again, it continued OK. BUT disconnect the mains even for a few seconds and the fault returns.
Any pointers gratefully received... TIA.

[Trevtron]

Re: Grundig 32 LXW 82-8600 DL (XLA194-03 PSU)

Well it was a boring Saturday afternoon, so I had another quick look at it. Turns out it wasn't much. It was C2056, a sick 100uF 50V which was wrapped up in heat-shrink, and wedged between a heatsink and a transformer.
Not a bad picture for such an old set

[bbccbb]

Re: Grundig 32 LXW 82-8600 DL (XLA194-03 PSU)

Well it was a boring Saturday afternoon, so I had another quick look at it. Turns out it wasn't much. It was C2056, a sick 100uF 50V which was wrapped up in heat-shrink, and wedged between a heatsink and a transformer.
Not a bad picture for such an old set

I have the same model, and the same problem... but it has a different power board.

Is the capacitor I'm looking for on the right from the bottom transformer? Left from the three blue capacitors (C29) and diode (D5)... where the white silicone blob is.

I'm asking because you did not provide a photo with metal plate removed and I can only guess what is under it...

[Trevtron]

Re: Grundig 32 LXW 82-8600 DL (XLA194-03 PSU)

It's over two years since I posted this, I had forgotten all about it! If you look closely at the image on the second post I have arrowed the offending cap (it's not very clear, sorry).
Despite the obvious differences, the power supplies do look similar in design, with an almost symmetrical layout. Do you have a capacitor (ESR) tester? If so it shouldn't be too hard to find the culprit. But from your image the component you refer to looks more like an inductor.

[bbccbb]

Re: Grundig 32 LXW 82-8600 DL (XLA194-03 PSU)

It's over two years since I posted this, I had forgotten all about it! If you look closely at the image on the second post I have arrowed the offending cap (it's not very clear, sorry).
Despite the obvious differences, the power supplies do look similar in design, with an almost symmetrical layout. Do you have a capacitor (ESR) tester? If so it shouldn't be too hard to find the culprit. But from your image the component you refer to looks more like an inductor.

I have something like this:
https://www.elektor.com/media/catalo...l._sl1000_.jpg

Maybe I could connect multimeter probes to it and check.
But... is it possible to make "in circuit" measurements?

[Trevtron]

Re: Grundig 32 LXW 82-8600 DL (XLA194-03 PSU)

I have been tempted to buy one of those testers but not got round to it yet.
Usually yes, esecially if the board is unplugged from the rest of the set. Occasionally a capacitace reading will be wildly off what you might expect, in which case you will need to carefully desolder one leg. But I do not think it will tell you a cap is good if it is not, even in-circuit
.

[bbccbb]

Re: Grundig 32 LXW 82-8600 DL (XLA194-03 PSU)

There is a negative coefficient thermistor hidden under silicone blob. When this area is heated with a heat gun I can power the TV without problems. Can thermistor go bad? Or something around that place? There are no cold joints around that place on the board.

[Trevtron]

Re: Grundig 32 LXW 82-8600 DL (XLA194-03 PSU)

I've never had a NTC go faulty, but I suppose there is always a first time, eh? But I do see several small electrolytics in the same area, you could try heating each one individually with the tip of a soldering iron to see if one of them gets it running.

[btokat]

Re: Grundig 32 LXW 82-8600 DL (XLA194-03 PSU)

I have the same problem. C2056 100MF/50 i changed it. fixed.

[btokat]

Re: Grundig 32 LXW 82-8600 DL (XLA194-03 PSU)

I have the same problem. C2056 100MF/50 i changed it. fixed. c2056 have plastic cover. near the u2000 transformator.