245BW, can't find problem. No 24 or 6.3V, standby is good.

[Yaaman]

Re: 245BW, can't find problem. No 24 or 6.3V, standby is good.

Hi selldoor
Not I didn't. I'll try after work. But that in my opinion doesn't explain such a randomness.

[selldoor]

Re: 245BW, can't find problem. No 24 or 6.3V, standby is good.

Can I just check - the bulb in your bulb trick device is a filament bulb? not a powersaver cfl or led. What wattage?

[Yaaman]

Re: 245BW, can't find problem. No 24 or 6.3V, standby is good.

It is good old style 100W incandescent bulb which is now banned in bloody EU. Fortunately I found some on eBay

[Yaaman]

Re: 245BW, can't find problem. No 24 or 6.3V, standby is good.

I've just connected everything together and unfortunately it's not working. Test bulb comes on and after 2s is pulsing quickly.

[Yaaman]

Re: 245BW, can't find problem. No 24 or 6.3V, standby is good.

It doesn't look good. I've got more than one issue.
I removed solder from pins 12 and 14 of ICM801 - MC33067. With logic board connected test bulb is coming on randomly. But when I use 2k resistor and I start the power supply board with it the test bulb never comes on.
I don't think the video board is bad as I have short circuit behind the J830 jumper (on the picture). When I reconnect the jumper I can see sparks and board dies.
I need your help guys.

[selldoor]

Re: 245BW, can't find problem. No 24 or 6.3V, standby is good.

Budm is your best bet but can you put up a picture of the whole of the bottom of the board- cant see one and as the OP posted off site they have disappeared

[Yaaman]

Re: 245BW, can't find problem. No 24 or 6.3V, standby is good.

Yes of course.

[Yaaman]

Re: 245BW, can't find problem. No 24 or 6.3V, standby is good.

Ok. I keep working. I've got all 24V and 5.3V now. I thought I swapped the zeners in 24V-to-5.3V section but I didn't. Anyway this part is now fixed.
I still need to find out why this power supply randomly making my "trick bulb" to light.
With video board connected test bulb always comes on. When I use 2k resistor the bulb comes on only sometimes. I really don't even want to think that the logic board is fried. I prefer to think it is because of the load.

Could it be because I used some Panasonic EB which are not low esr caps?
How do I diagnose that? Please help.

[WiseguyTom]

Re: 245BW, can't find problem. No 24 or 6.3V, standby is good.

I had the same problem with my syncmaster 245B (which has a BN44-00195A power supply).
Blue light came on but no image on the screen.

I was able to fix it and want to share my experiences.

At first, the problem was intermittent.
Sometimes an image was displayed and then suddenly it went black again.
Hitting the back or side of the screen a few times, often brought back the image.
But I had to hit it harder and harder to get the image back and after a few weeks I deciced to have a look inside.
After visual inspection I saw nothing special, no bad capacitors or resistors.
Also the fact that hitting it often/sometimes brought back the image made me believe it's not caused by an electronic component but by something else.
But what? A bad or loose transformer was my first guess.

I took out a DVM and started measuring on the stand-alone power board.
Standby 5.2V was ok. Connected it to the Pwr-On line to activate the other output voltages.
Nada, no 24V.

Then I started bending the PCB, pulling up one side while holding down the middle.
Don't do this with you bare hands or you'll get electrocuted!
All of a sudden, the 24V appeared!

Then I stumbled on this blog:
http://blog.whitesites.com/How-to-Fi...97265_blog.htm

Here they mention soldering joins that went bad.
So I re-soldered all big end medium joints and that did the trick.

So get your soldering iron out guys!

Cheers,
Tom