Belinea 10 19 10

[Scenic]

got this 19" LCD for free.

it worked fine when i first plugged it in, but now, it's dead

thats the problem why i got it for free... works when connected for the first time (after sitting without power for a while), and then it's dead..

seems that someone was already in there, as the PSU board has solid polys in there (i doubt that it came with those, maybe usual crapcaps like on the video-board (Teapo))

problem is that i have no real idea what to check.. !?

fuses are okay... no cracks in the solder joints...
and absolutely no output. should be 12V (at max. 1,75A)

i wonder what's the reason for this?!

i doubt that the polys are the reason for this, because the guy i got it from used it for a while (about half a year) before it started to get flaky..

any ideas..?

PSU board is made by Fortron Source.
Model: FSP035-1PI01 M

http://bambooz.pytalhost.net/badcaps...a/DSC06714.JPG
http://bambooz.pytalhost.net/badcaps...a/DSC06718.JPG

[Scenic]

Re: Belinea 10 19 10

damn edit limit -.-!

i also tried to discharge the primary cap to see if it comes back to life.

no luck. still dead.

i honestly don't know what teh hell is wrong with this thing...!?!

*if* it works, everything's fine. clear pic, bright, no obvious noise or something.. (like a high pitched whine..)

i could try to replace the polys, but the only caps i have at hand for that are Rubycon YK general purpose ones (16V 1000uF)

[zandrax]

Re: Belinea 10 19 10

In the first picture, left upper corner, the two pair of cables (pink and white) are unconnected. Did you detach them or were they already unconnected?

Zandrax

[i4004]

Re: Belinea 10 19 10

what to do?
measure voltages when it doesn't start as opposed to when it works.
what happens to output, is it heailly damped?

if it is it suggests short circuit somehwere on the secondary side.
if so
http://www.electronicrepairguide.com...nd-router.html
if you don't have supply, there should be ways to make regulated supply from pc psu.

btw. are you suggesting it works when cold?
that means you may have cold joint.
not many components on that psu so you could try that first.
prior to that you could try heating it with hairdryer to see if temp makes it cut the power.

[Gianni]

Re: Belinea 10 19 10

Hi Scenic

can you investigate with a scope or DMM?

You can find here the datasheet of the CCFL controller for the inverter lamps.

I don't see the PS controller but from the first picture I see Output: 12V 1.75A.
If you can identify where the 12V is connected you can check if it is present.
If PS doesn't work, you can try connecting an external PS and see if the board works.

Ciao
Gianni

[Scenic]

Re: Belinea 10 19 10

@ zandrax: i disconnected those. wanted to take the PCB out and forgot to take a before-photo.. so i made one after unplugging them..

@i4004: unfortunately it has nothing to do with the temperature :/
went over all suspicious looking joints with my iron... didn't change anything..
letting it cool down (i put it on the balcony for 10minutes.. -2°C out there ... brrrr) and heating it up with a hair dryer didn't help either..

on the output side theres really nothing going on.. 0,00V
also no direct short on the secondary side (so the caps don't seem to be the reason for this..)

@ gianni: i don't have a scope :/
only my trusty old Xerox 600T1616 DMM ..

the problem with trying to use an external power supply is that the video board has some sort of standby line going to the PSU board (something like the 5VSTDBY on a PC Mainboard to turn on the PSU i guess)

this is really weird...

once it's dead, you cant do anything to make it work again..
only option is to let it sit without power for a day or longer..

but that has nothing to do with the input cap still being "charged up" as i tried to discharge it with a resistor, checked that it's discharged with my DMM and connected the power again..
still no go..

there's nothing getting unnormal hot till now. at least i couldn't find anything yet..

i'll get the board PSU board out and try around a bit.. maybe i'll find a short somewhere.. but if there's a short, why does it sometimes still work then...?!?

this is weird

[i4004]

Re: Belinea 10 19 10

stays charged?
was just reading this
http://www.electronicrepairguide.com...-problems.html

either way, concentrate on that cap, as that doesn't seem like normal condition(cap remaining charged).

can you find datasheet for pwm ic?
to check if it's getting supply, and if it's producing output pulses, are they reaching the main switcher, etc.

when the output is at 0v is primary side switching at all?
if it is then it should be the trafo itself.

[Scenic]

Re: Belinea 10 19 10

it stays charged for a while (voltage falling constantly)

i always discharge those primary caps with a huge old resistor before doing something on a PSU board because i got shocked (in general, not on this board) by those caps a lot

but i just noticed something...

notice the negative side marked on the PCB..




now look at this one...



didn't notice that before..

all polys on that PSU board are connected in parallel (12V output)
and one of those 4 caps (2nd pic) has been soldered in the wrong way (polarity)


i'm gonna remove it and test again... just need to wait for my dumb soldering iron to get hot enough... takes like forever to heat up *hmpf*

[kc8adu]

Re: Belinea 10 19 10

surprised that cap didnt explode!
yes poly will blow up if reversed.i tried it just to see.
and replace the other lytics as well as any 200k-1m resistors on the primary side.

[Scenic]

Re: Belinea 10 19 10

well.. that cap seems to be open..
maybe thats why it didn't explode.

but removing it didnt help.
anyways... i tried to check the video board to see if it still works (if not, fixing the PSU would be a waste of time..)

connected a 12V 1A PSU to the pins of the video board (located positive and negative by following the traces to a cap)
it turns on and shows the usual "no signal" message.. so it's ok. (allthough you can't turn it off with the power button because of that standby line thingy)

@ i4004: just checked that primary cap again..
after removing the power cord it stays charged for about 5minutes.. constantly discharching..

[Scenic]

Re: Belinea 10 19 10

god damn.. i begin to really hate this 10minute edit limit
---
okay i just fed this beast with an external power supply (12V).
but this time not only the video board but both boards, as the inverter circuit is also running off the 12V rail..

suprise..







and i just found an open resistor on the primary side...


edit: i also thought about reworking it to use an external PSU brick, because i have plenty of them lying around and this would keep the heat (which discolored the PSU PCB already) out of the LCD..

but i'm still trying to fix it.. just to have a little challenge

[Scenic]

Re: Belinea 10 19 10

i replaced the open resistor R320 (covered in heat shrink tube ; on the right of the primary cap) and it came back to life

still running opened with a signal coming in.

damn.. this thing is really hot-running..

considering the metal cover isn't on it yet i may rework it to use an external psu brick..

getting a bit too hot IMO.. but working fine..

thanks i4004 for that link in post #7..

[FIXITNOW]

Re: Belinea 10 19 10

what value was resistor ?

[i4004]

Re: Belinea 10 19 10

you should replace both (r112 too) if it was taking the beating because of r320.

what's getting hot?
put a small fan?

btw. for how long NOW the cap stays charged?
let me guess: a second, if that...

[Scenic]

Re: Belinea 10 19 10

33k
replaced the other one too..

those heatsinks get so hot that you can barely touch them for longer than a few seconds.
seems to be normal, because the whole PCB changed the color on the bottom from green to brown-ish already..

a small fan (40mm) wouldnt fit in there (height) and wouldn't make much sense, as there's a metal cover over those PCBs with only a few air vents...
but you can't leave it without this cover, because the foot of that LCD is screwed onto that metal plate/cover.. :/

cap stays charged for about 3secs now..

i'm actually reworking it to use an external power brick.
it's just getting too hot IMO..
heats up the LCD Panel from the back pretty much..

and as it's working fine with a (recapped) external power brick (12V 2,5A) and there's no difference in the backlight brightness (compared to the original PSU) i think its OK like that..

[zandrax]

Re: Belinea 10 19 10

Fortunately you found the reversed cap and the burnt resistors: since it runs hot, can't you add some cooling vents in the rear plastic case? I know there is the metal plate, but the vents may help in cooling it.

Zandrax

[Scenic]

Re: Belinea 10 19 10

i worked for the trashcan.

the panel is f*cked..




this should be black. (the dark spots in the lower middle are from my cam..)

just didn't notice this before because i set it to min. brightness to take photos..

[PCBONEZ]

Re: Belinea 10 19 10

I would keep working on it.
Previous re-cap installed some caps backwards.
Look into that (and replace those caps) and you might get the unit back in service.

[i4004]

Re: Belinea 10 19 10

on the 2nd image, is that flash of your camera, or is it hell?

if problem is slight non-uniformity on higher brightness...well..don't look at uniform surfaces, just like you normally wouldn't..heh...

this crt of mine has come discoloration(visible on white screen) on particular spots, but nobody can notice that unless one stares at the white screen...and if you do that, i think monitor is the least of your problems...hehe...

if you still mind, sell it...to somebody with crt that reads a lot; he'll appreciate it allright...

[PCBONEZ]

Re: Belinea 10 19 10

Hmm,
Looking back maybe I interpret photo of screen wrong.