Fujicom LCD LC3201 No Power

[s_henya]

Hey guys,

I got this TV for repair it for a freind,

Got no power at all,

PSU MLT666 Rev 2.7

Had 4 bad caps:
3X 1000uf 10v
1X 470uf 16v

5A main fuse,

I had a feeling that fuse didn't blow for nothing
tested diode bridge, seemed fine,

Had a quick test and big bang!

Did another quick test and found
2 Power Mosfets: p6nk60zfp blown
And may got more blown transistors,

any suggestions?

[s_henya]

Re: Fujicom LCD LC3201 No Power

also FSU05B60 shorted

[selldoor]

Re: Fujicom LCD LC3201 No Power

Well assuming you are going to replace all you have found faulty there is little to add. On the back of the board picture top right are those the mains posts?
and the brown streak across the ground screw pad has it shorted out there?

When you have replaced all the parts next time you start it use a 75w filament bulb in series with the mains positive. - "Dim Bulb Test" - should save you blowing more components if there is still a short on the board.
I suppose as you remove parts you could also test the pads for a dead short.

Forgot to say - where is bad on the back check the board has not carbonised one of these
MLT boards used to do it around the high voltage blue caps.

[s_henya]

Re: Fujicom LCD LC3201 No Power

hey selldoor yes i will try to locate parts locally or replacements and update..

[s_henya]

Re: Fujicom LCD LC3201 No Power

p6nk90z will fit?

[selldoor]

Re: Fujicom LCD LC3201 No Power

Looks ok to me - you will need to get the correct fitting (insulated backplate or metal?)

[s_henya]

Re: Fujicom LCD LC3201 No Power

got insulation for the FET and screw.
for the diode FSU05b60 i got STTH12R06FP

really dont know if the diode will fit...

[s_henya]

Re: Fujicom LCD LC3201 No Power

not very good news, fuse and 2 fet got blown again.

don't really know why, (incompatible parts, another short)

any more testing tips before i will order a whole board i already invested 15$ on parts
that i will have to order again.

Had that problem before with a another PSU, i was suggested to replace the driver ic
https://www.badcaps.net/forum/showthread.php?t=28186

i still have one in stock,

should i have another go at ordering fets and try again?

[selldoor]

Re: Fujicom LCD LC3201 No Power

Take it you didnt do this then:
When you have replaced all the parts next time you start it use a 75w filament bulb in series with the mains positive. - "Dim Bulb Test" - should save you blowing more components if there is still a short on the board.

[s_henya]

Re: Fujicom LCD LC3201 No Power

I had a felling i forgot somthing :-(

i will make the cable now.

just a 75w bulb in series?

[selldoor]

Re: Fujicom LCD LC3201 No Power

Yes - basically.
Type dim bulb test into google

[s_henya]

Re: Fujicom LCD LC3201 No Power

just found 3 more bad caps:
2X10uF 50v
1X100uF 35V

what about the IC worth replacing the fets again and the L6562D?

[selldoor]

Re: Fujicom LCD LC3201 No Power

Its up to you - depends on the value of the set and how much you want to spend on it.
Perhaps a replacement board would be the way to go.
Regards the IC - tested the old one for shorts? I see you were told about the dim bulb test
in that previous post as well.

[s_henya]

Re: Fujicom LCD LC3201 No Power

I was too lazy to bulid it,

but just now i have finished it (bulb in seires tester)

i ordered the parts from ebay and aliexpress (this time i got the original parts)

a used board isn't expensive at all,

but i want to learn to solve this kind of psu problems.

i fix computer psu also, they have the same problems...

IC has to go short in order to fail?

last time the IC was the blame for blowing the fets.

[s_henya]

Re: Fujicom LCD LC3201 No Power

UPDATE:

got the FETs & Diode.

did some more tests, found one zener diode IN4739A shorted
it is located near the fets and the diode that got blown.

So my guss is that the zener caused the fets to blow the second time.

i got some bad news,
i dont know if its me who broke it, because i work on a foamed surface
but i got a tiny smd transistor broken W2T

any ideas about a replacement?

i plan to replace many of the elec' caps, many were out of range/ high esr.

[s_henya]

Re: Fujicom LCD LC3201 No Power

i didn't recieve the caps from ebay, so i decided to buy them locally,

i used the dim bulb tester, and the light came on (on the bulb)

i don't know what to expect..

any help would be appreciated..

[s_henya]

Re: Fujicom LCD LC3201 No Power

after reading some on the bulb tester,

good psu makes the bulb light then dim
bad (shorted psu) makes the bulb stays on.

my psu i still shorted acording to the test.

i checked ad found the i still have a short on the zener i replaced, but out of the ciruit its fine.

i have some resistors in parallel to it, could it be the reason?

[s_henya]

Re: Fujicom LCD LC3201 No Power

i replaced today the FET driver chip,

Used the bulb tester, got a light for a sec then a little dim,

got standby light!

decided to remove the tester and plug it directly,

fuse blown..

i need some explenations...

with my meter i can see there is a short on the fets legs and zener,

but i dont know if its a real short or some coil or resistors in parallel.

(The fuse original rating were: T5AH 250V)

i used euss 5a pico fuse maybe its not suitible?

i never used picofuses before. (its nice they wont explode as the normal glass fuses)

please guys i must figure this one out....

[s_henya]

Re: Fujicom LCD LC3201 No Power

after testing the zener got shorted again.

so in full power the zener gets shorted,

while using the bulb tester i got standby voltage.

please guys any tips?

[budm]

Re: Fujicom LCD LC3201 No Power

Can I see the location where this 9.1V Zener is on the board, also the MOSFETs?