sharp lc37d44e-bk short on 35v line

[dellxps15]

hi, a friend gived me that tv for checking for some bad caps.

tv as he said power on then off, so i thouth it was a bad caps to be replaced and told him i could give a look, but after i got it and opened the tv, i see all caps looking ok. tried to tutn on tv, but i got only backlight. put another tv connected to scart and still no picture on 2nd tv. so i tried remove tcon cable and after removing them both, i got picture on the second tv.

i looked on google for same av board and found a russian discussion with same problem as mine.
http://monitor.espec.ws/section31/topic175837.html

as i can read fro ma translated bad version to my language i see the dude was able to fix it but removing the short on 35volt line, but dunno how he did.

on that picture:

http://monitor.espec.ws/files/2011-05-15_192231_920.jpg

i have 0volt if i connect right side of lcd (looking it from the front ov tv).
if i dont connect right side, i have all voltage ok.

if i connect only the left side tcon cable, i got half picture like picture attached.

is this tv possible to be fixed or is a bad panel and i cant do anything ?


tnx for your suggestion.

[budm]

Re: sharp lc37d44e-bk short on 35v line

You have shorted circuit in the panel, probable the SMD IC on the flexible circuit board attached to the LCD Glass panel, nothing you can do if that is the case, it can also be shorted CAPs on the long PCBs that the flexible PCBs are attached to.

[dellxps15]

Re: sharp lc37d44e-bk short on 35v line

hey tnx badm for always replying and helping
i misured all caps and they have gnd only one side, so they are ok.....

so you think is bad panel?

av board is ok ? (it should as it is ok if i remove right side of tcon cable.)

upper side of lcd connectors looks ok. dunno if downside must be something wrong.....

[budm]

Re: sharp lc37d44e-bk short on 35v line

Same symptom as this one :https://www.badcaps.net/forum/showpo...7&postcount=10

I end up keeping boards for spares.

[dellxps15]

Re: sharp lc37d44e-bk short on 35v line

yes.... so not repairable.


tnx very much for helping

[dellxps15]

Re: sharp lc37d44e-bk short on 35v line

while was doing some test, now i have 14.5 volt on the 35 volt rail. what is wrong now according to measurement ?

[dellxps15]

Re: sharp lc37d44e-bk short on 35v line

how can i fix that 14volt instead of 31-35 volt ?

[tom66]

Re: sharp lc37d44e-bk short on 35v line

It sounds like the charge pump IC or diode has failed and you are just getting AVDD (15V), this is due to the panel fault so if you fix it, it will probably just fail again.

[dellxps15]

Re: sharp lc37d44e-bk short on 35v line

It sounds like the charge pump IC or diode has failed and you are just getting AVDD (15V), this is due to the panel fault so if you fix it, it will probably just fail again.

i will fix it so av board can be sell as working

i wont connect lcd to make it fail again

so what component could be damaged in the picture? as in these mosfet i have 35 volt.

edit: these measure are done without lcd connected. if i connect lcd as said before, i have 0volt instead of 14.5volt.

[tom66]

Re: sharp lc37d44e-bk short on 35v line

I would try replacing D8408

[dellxps15]

Re: sharp lc37d44e-bk short on 35v line

tnx for replying. how could i know what component is it ?

[tom66]

Re: sharp lc37d44e-bk short on 35v line

A dual diode of some sort usually, schematics may be available in service manual. Here is how I repaired a T-con with VGH fault:
https://www.badcaps.net/forum/showth...r+t-con+chimei

[dellxps15]

Re: sharp lc37d44e-bk short on 35v line

removed d8408 but i had the same voltage....

what next ?

[tom66]

Re: sharp lc37d44e-bk short on 35v line

Removing a part doesn't eliminate the possiblity of it having failed open circuit. You need to replace it, if you want to repair, no guarantees though other parts could be bad too.