Packard Bell CT700p shutting down

[tom66]

Re: Packard Bell CT700p shutting down

Well, I had it completely open when I used the computer PSU so it could be some overheating inside the display, it was pretty hot when I opened it an hour ago. Trying to cool it with fan now, maby something will change.

I think we have some supplies here, will ask what exactly.

ADD// well, having the dispaly out of plastic cover with fan blowing on the metal cover, it is running fine for ten minutes more than usually :-)

Are there any caps on the main controller board?

[Behemot]

Re: Packard Bell CT700p shutting down

Yeah, several caps of very small high, I've already change some of them for higher capacity (some of those which sit on input). Do you suggest complete recap just for case?

[tom66]

Re: Packard Bell CT700p shutting down

Yeah, several caps of very small high, I've already change some of them for higher capacity (some of those which sit on input). Do you suggest complete recap just for case?

Well, it sounds like a thermal problem. First look for any cold or bad solder joints.

Cold joint: http://en.wikipedia.org/wiki/File:Co...der_joint2.jpg
Bad/broken joint: http://en.wikipedia.org/wiki/File:Ge...oetstellen.jpg

[Behemot]

Re: Packard Bell CT700p shutting down

Still running. OK, I'll open it tomorrow, do somplete recap and resolder every suspicious joint. Also try to reconnect all cables

[Behemot]

Re: Packard Bell CT700p shutting down

So I've swapped all caps on the data board and also resoldered almost everything bigger than SMD caps (but I did SMD transistors). The result is, the monitor is still running (this is success itself), athough one thing happenned, when I turn it off, it does not show completelly black screen, but 100 % white

Anyway, I'll let it running and see whether it will turn off again or not.

[PlainBill]

Re: Packard Bell CT700p shutting down

So I've swapped all caps on the data board and also resoldered almost everything bigger than SMD caps (but I did SMD transistors). The result is, the monitor is still running (this is success itself), athough one thing happenned, when I turn it off, it does not show completelly black screen, but 100 % white

Anyway, I'll let it running and see whether it will turn off again or not.

Trace the inverter On/Off signal back to the processor on the signal board. If you only worked on the signal board, odds are you introduced a short somewhere.

PlainBill

[Behemot]

Re: Packard Bell CT700p shutting down

Bad news. Display turned off after 35 minutes. After another ten seconds, it even got black. Forever

Two burned transistors on the inverter board, labeled DK QE. Don't have an idea what they are, did not find anything. Those are two probably switching transistors righ before one of the two transformers. Second half looks to be fine (two mirrored sides for two CCFLs).

It looks like the DK and QE are only labels of the actual voltage lines, not the transistors itself. I guess those are just FETs, N channel maybe?

Also which fuse would you suggest, original is 4 A, I have 3,15 A and 5 A.

[Behemot]

Re: Packard Bell CT700p shutting down

I desoldered the transistors and tried to connect just one CCFL. There was also some resistor which overheated on the second half of the board, its desoldered too, now. I guess there is some protection which disables it when only one CCFL is running because it blinks for a while (two seconds or so) and turn off.

According to LED, data board reacts on being plugged into computer (changes from orange to green and otherwise after siconnec of VGA cable). But the LCD itself is black, not only there is no backlight. I guess I have to change the transistors and hope there is no IC damaged on the inverter board

Anyway, thanks for your support up to now guys!

[PlainBill]

Re: Packard Bell CT700p shutting down

I desoldered the transistors and tried to connect just one CCFL. There was also some resistor which overheated on the second half of the board, its desoldered too, now. I guess there is some protection which disables it when only one CCFL is running because it blinks for a while (two seconds or so) and turn off.

According to LED, data board reacts on being plugged into computer (changes from orange to green and otherwise after siconnec of VGA cable). But the LCD itself is black, not only there is no backlight. I guess I have to change the transistors and hope there is no IC damaged on the inverter board

Anyway, thanks for your support up to now guys!

Those transistors are Rohm 2SC4672. They are available from Digikey and other suppliers for about $.75 each.

PlainBill

[Behemot]

Re: Packard Bell CT700p shutting down

Oh man pity there is no karma on this board, I would give you + every day :-)

Unfortunately these are not here. I can take some when me or somebody else here will be ordering from digikey. Is there any replacement I can use which could be found here? I will also ask nearby shops.

[sam_sam_sam]

Re: Packard Bell CT700p shutting down

Here is one place you might be able to get some

http://china.futureelectronics.com/en/Pages/index.aspx

http://www.findchips.com/avail/?part...tm_medium=Link

[Behemot]

Re: Packard Bell CT700p shutting down

Well, I am afraid that only the postage itself would outrange the price of this display. I thought about something in Prague at best

[PlainBill]

Re: Packard Bell CT700p shutting down

Oh man pity there is no karma on this board, I would give you + every day :-)

Unfortunately these are not here. I can take some when me or somebody else here will be ordering from digikey. Is there any replacement I can use which could be found here? I will also ask nearby shops.

I apologize for missing your location info. As often as I bug people to include it in their profile, I should at least check for it.

How are import duties in the Czech Republic? This eBay auction has them at good prices - and free shipping. You might even want to get a few more, he has 10 for sale in this auction.

PlainBill

[Behemot]

Re: Packard Bell CT700p shutting down

One shop answred me they can order it, it will be here in ~2 weeks. So I'll report than. Thanks for now