Logik LCXW32HD1-Standby Transformer Problems

[scooby-doo]

Hi Andy

Yes it has been turned on with U4 the wrong way round, this is when I got the flashing control panel lights, turned it back round and now I just get the very dim standby light, since my last post I have replaced U4 and still have the same fault.

[Ohm Supplies]

I'd think that the scaler board is damaged from the opto, i've seen it a few times and not managed to repair the board.

regards
Andy

[scooby-doo]

Hi Andy
I know its all confussing, but the PSU I am working on is the one that HASNT been turned on with U4 upside down.

Or when these boards fail is there a chance this damage will be caused anyway, judging by the fuse in this board it was a large short.

Is there anywhere else you can direct me too with my DMM to confirm this is Fubar'd

Cheers

[Ohm Supplies]

Hello,

WHen the boards blow its not that common to have a problem on the scaler however the opto being in the wrong way nearly always causes problems, the symptoms are dead, all the lights on the front on permanently or if you’re lucky the front buttons not working and the remote control being the only way to get the set on. Putting a working or repaired psu in wont sort the scaler and it would have to be replaced
Regards
Andy

[scooby-doo]

Hi Andy

Right I understand now, so what you are saying is I could go out buy a gleaming new psu and the problem will persist.

What I am finding hard to understand is that if I plug the PSU just using the AC plug (like you told me to do to check between c45 & C55) if I leave all other cables out of the board and check all the terminals on the board I am not getting any voltages at all just 5.10v from 5vs and 1.8v from STB.

Wouldnt there be a voltage at 12v or 3.3v or would all the other boards need to be plug in to stabilise all the other voltages.

[Ohm Supplies]

Depending on the design of boards, some psu’s are switched on by the main board, others will have all the voltages present (17pw boards are the best most common example).

You can switch most boards while on the bench by adding voltage or sometimes earthing. Not only does this mean a test can be done with out the rest of the set (although the set does not run with a load) it also tells you if the fault is on another board as is the case with this set.

If you look at the general forum on this site about the diagnostika tool, this is a palm sized device that works on this principle, simply because its how power supplies work.

We did some service info. a few weeks back showing how most engineers do this on a practical level.
Regards
Andy

[scooby-doo]

Hi Andy

Cheers for all you help on this one mate, my next question is do you have a scaler board in stock?

[Ohm Supplies]

Sorry no,

You can get the scaler from a scapper (it the little board on the right going to the screen and the psu) but if the psu has been repaired then it might of been damaged with the opto being incorrectly fitted.

regards
Andy

[johnboy183]

Hi,
 I have also been working on one of these boards for some time now and I am not sure if I also may have unintentionally put U4 in the wrong way round. I can't easily find a photo or description of which way round it should go.
Usually the boards are marked quite clearly (with a number "1") to show where pin1 of the opto (the one with the dimple next to it) should go. However all of the other optos on this board dont seem to follow that pattern and the printed "1" is on the opposite side to teh dimple! (none of these others have been out of the boardso they are as original)
Can anyone tell me the correct way round as I dont wish to change mine and find it was correct to begin with?
regards
John

[Ohm Supplies]

John,

INfo. on fitting the opto and checking the transformer is on the backer that comes with the kit, failing that, you can check but fitting the opto. the same way as the other 2. (the nearest being the other side of the stand by transformer or as always with opto's, follow the line that splits 2ndary/primary

regards
Andy