evesham v32eccb no power

[snipersquad100]

Hello
I got this evesham v32eccb tv given to me. it's a 2006 model.
There is no power what so ever coming out of it. I can see scorch marks around two fet's and on the underside there is a hole in one of the chips (see pics) this is a stab in the dark but there is no burning on the chip, it looks like its been chiped some how "Pardon the pun". Is it possible that chip is ok??
I haven't done any other checks yet, just a visual inspection.
I will need a schematic if anyone got one cos if im going to repair this I will need to know what part the chip is as the hole on the chip had the numbers on it. Thank you...
p.s. I think the board is a wannien 101vo 0544 or the board number is the one in the pic not sure.

[tom66]

Re: evesham v32eccb no power

No, the chip is destroyed. This will happen if the FETs fail. I have a Vestel PSU here with a blown SMPS IC too. It actually put a very nice black mark in the back metal behind the screen.

[snipersquad100]

Re: evesham v32eccb no power

Only the one fet is blown "p14nk50zfp" but cant get the part on ebay or cpc, maybe no point if I cant get that ic number.

[tom66]

Re: evesham v32eccb no power

It's a 14N50, just find a similar part with:

- RDS(on): same or lower
- Qg: same or lower

[snipersquad100]

Re: evesham v32eccb no power

Closest I can find is STW14NK50Z, it has the same data sheet, think its just a different package. now just need to find out that part number on the blown chip. then I can order them and learn how to solder a small smd chip lol.

[snipersquad100]

Re: evesham v32eccb no power

.

[snipersquad100]

Re: evesham v32eccb no power

Hi Tom, I bought this STW14NK50Z, I didn't realise it was a TO-247 package. Do you think it work if I bodged it in.?

[snipersquad100]

Re: evesham v32eccb no power

I also need to know how to identify pin 1 on the chip ic2. as you can see in the pic there's no marks to let you know which way it needs to go. Do I use the writing as a reference and put it on the same way as the writing on the chip on the pcb?

[snipersquad100]

Re: evesham v32eccb no power

Just an update, I've soldered in the new chip, don't know if it was the right way around as there's no mark to see what is pin one, so I put it in with the writing the same way around as the one that came out. Changed the fet's to w14nk50z they a bigger package with metal back so cant be put on the heat sink as it shorts. Also had to change the fuse and the main cap as it was measuring in the nf region not 150uf, it wouldn't even register on the esr meter. I got a 5v on one of the pins but when I connected the psu to the tv it is fluctuating, tv wont turn on but there a orange flashing led on the front.
Any ideas anyone.
thanks.

[snipersquad100]

Re: evesham v32eccb no power

I need a schematic

[tom66]

Re: evesham v32eccb no power

What voltage across the 450V capacitor?

[snipersquad100]

Re: evesham v32eccb no power

333 volts dc, I did change this cap, the old one was 180uf 400v the one I put in was a 2nd hand one 220uf 400v and just within the esr range.

[tom66]

Re: evesham v32eccb no power

The PFC controller is not working then, did you check the resistor from the SOURCE pin of the MOSFET you replaced is OK? (Resistor goes from SOURCE to the negative of the big cap.)

[snipersquad100]

Re: evesham v32eccb no power

Cant find a resister going to source to neg on big cap but there is on from drain to positive R10, which is measuring 0.24M ohms in circuit. It says 3323 on the resister, is that 332k ohms?

[snipersquad100]

Re: evesham v32eccb no power

This pic might be better, it showing straight connection from source to neg on cap and the other fet going to the ic2 I changed.

[snipersquad100]

Re: evesham v32eccb no power

Could this be the PFC path going to pin 1 of ic1?
R10 goes to R11 "throu hole" not the neg of big cap like I said 2 comments up.
R10 R11 R12 are connected in series "3323 0.24Meg 3323"

R11 is orange orange red orange gold

[snipersquad100]

Re: evesham v32eccb no power

I've been looking at a repair kit for this psu http://www.ohmsupplies.co.uk/REPAIR-...BOARD-UP220-AE

•F1•IC5•Q5•R31•R32•ZD1•C28•C39 seem ok except for zd1 which is showing a short, don't know if its because its in circuit.

[tom66]

Re: evesham v32eccb no power

My mistake, the PFC is Q8 + IC1, etc.
You have only 330V across the main cap.

This means
- PFC is not turning on
- Chance of both PFC & main 24V output (possibly 12V) also being bad is unlikely
- Main board is sending PSON signal? Check this.
- Check voltage at Vcc of PFC IC - possible IC2 is loading it down...

[snipersquad100]

Re: evesham v32eccb no power

Well what do you know, I changed ZD1 which was a 1n4746 with a BZX85C and the tv came back to life. So all in all I changed the zener diode, main cap, 2 fets, 1 chip and a fuse. Now I know the tv works i'll have to buy the proper diode, fets as they are to big, proper cap as it to big to fit into the psu casing, and a proper fuse as I bodged in a 4 amp fuse soldering legs onto a normal fuse.
Well all done, Thanks Tom66 for you help as usual.
Just wish manufactures would be more relaxed in sharing their schematics especially ones like evesham who went out of business in 2008.
Thank you

[tom66]

Re: evesham v32eccb no power

Nice one.

Evesham didn't make the TV, it is made by a (probably Chinese) OEM.

In China, they tend to guard schematics with care, because there is so much copying. There is very little one company can do about another copying them. Releasing schematics, even just basic block diagrams, would be bad for them.