Please help me Packard Bell Maestro W220 3 seconds backlight

[me.just88]

Hi to you all i'm new to this forum so be a little gentle,ok so i have a 22" Packard Bell monitor with a common 3 seconds backlight problem.
At first i thought that it has bad caps or bad lamp,then i inspected the caps to see that no one of them are bulged.
next i have put my sparing lamps to see witch one is bad,and to my surprise one pare of lamps dind't start at all,i changed again the laps wich didn't power on with other spare lamps,and again the same problem,please help.

[CapLeaker]

Re: Please help me Packard Bell Maestro W220 3 seconds backlight

O.k. we need a picture of YOUR inverter board. What you can do now is to verify each of the transformer outputs with your ohm meter and check if there is a bad transformer. They should be within 3% of each other.

[me.just88]

Re: Please help me Packard Bell Maestro W220 3 seconds backlight

here are the photos,i forgot to mention that my board is PI 190DTLB 5,now i will try to check the transformer

[tom66]

Re: Please help me Packard Bell Maestro W220 3 seconds backlight

Moved to a more appropriate forum

[me.just88]

Re: Please help me Packard Bell Maestro W220 3 seconds backlight

sorry bad for bad posting.
There is a problem,i don't know how to check the transformer,any instructions or tutorials will help. thanks

[vinceroger69]

Re: Please help me Packard Bell Maestro W220 3 seconds backlight

whats the details from the top of the transformers

[me.just88]

Re: Please help me Packard Bell Maestro W220 3 seconds backlight

i don't think that i get the question, "CapLeaker" said to me to "What you can do now is to verify each of the transformer outputs with your ohm meter and check if there is a bad transformer." and i was saying that i don't know how to do it.
when you said the details from the top of the transformers i understand the numbers written on it,and they should be in the photos above,if that's not it,i don't know what other details. thanks

[vinceroger69]

Re: Please help me Packard Bell Maestro W220 3 seconds backlight

yes if you can post the numbers from the top of the transformer we can see which are the primary and secondary winding and help you test them i cant read the numbers from the pictures sorry.Have you got a multi meter to test?

[me.just88]

Re: Please help me Packard Bell Maestro W220 3 seconds backlight

I have a multi meter,if it helps i have also an osciloscope,but i don't know to use it
anyway on inverter transformer i have:
730 703-190DTLB-DH
EEL19-AD1700
DARFON 2025E 734075

the yellow big transformer:

730-102-170DTLA-AH LAE ER2817 0734

[vinceroger69]

Re: Please help me Packard Bell Maestro W220 3 seconds backlight

I cant seem to find much information about these transformers maybe budm with have a idea which pins to test theres some good pictures of the windings and pins in this ebay link
http://www.ebay.com/itm/2X-TRANSFORM...-/260737091450

[Joe Black]

Re: Please help me Packard Bell Maestro W220 3 seconds backlight

Use your DMM on Ohm setting and just compare the results of the transformers.
Not likely that both have failed...
If they test same (or about 5% +/-) they should be OK and you will have to check MOSFETs which actually drive those transformers.

Failed MOSFETs will have shorted D and S pins, so google datasheet, ohm setting again, lift pins of board and test.

[budm]

Re: Please help me Packard Bell Maestro W220 3 seconds backlight

The primary side of both inverter transformers are connected in series and driven by half-bridge drive design, since you are getting one set of the lamps to come on, that means you may have open winding on one that does not light up.

[me.just88]

Re: Please help me Packard Bell Maestro W220 3 seconds backlight

i've compared the invertors and like Joe Black said the result where not identic, after that i changed the bad inverter and now is working just fine.thank you everyone for ideas and fast response.

[Joe Black]

Re: Please help me Packard Bell Maestro W220 3 seconds backlight

i changed the bad inverter and now is working just fine.

Please elaborate for future reference

edit: I guess by inverter you mean transformer?

[me.just88]

Re: Please help me Packard Bell Maestro W220 3 seconds backlight

ok sorry,so this is what i've done, I put the DMM on ohm meter,then checked the transformer pointed in picture below,and I read value 1 (I mean nothing happend actualy) after that I checked the other transformer and i read 740,then i realised that the one with 1 value was broken,after that i replaced the one with problems,and that was it.
I hope that my answer helped.
thank all for your help.

[budm]

Re: Please help me Packard Bell Maestro W220 3 seconds backlight

OK, thanks for the follow-up so you did have one transformer with open winding on the secondary high voltage side.

[me.just88]

Re: Please help me Packard Bell Maestro W220 3 seconds backlight

it seems that the thin wire within the transformer has broken from nowhere,I've had other monitors that when one of the transformer was bad,the simptoms were diffrent,both lamps where lighted halfway. no light at all it will be a first.

[me.just88]

Re: Please help me Packard Bell Maestro W220 3 seconds backlight

it seems so.