Samsung 231T, recapped, no power, no lights

[selldoor]

Re: Samsung 231T, recapped, no power, no lights

I am assuming ref to a 213T is a typo - you can edit it if your quick

Your right it doesnt have the fuse detail however if you look at the 'silver' ends of the main fuse it has the details on it. Have you tested the fuses? if they are good you dont actually need the detail

Its always better if we can see your boards as we may spot
problems

The suggestion to replace caps after the mosfets is because the mosfets may have failed because as caps fail they put pressure on other components eg mosfets
so if you have replaced mosfets it makes sense to replace the caps that may have contributed to their demise.

[RalphSimon]

Re: Samsung 231T, recapped, no power, no lights

The original post in this thread starts

Samsung 231T, recapped, no power, no lights
My search shows no successful repairs on this particular Samsung 213T Syncmaster LCD model....

Mine is a 213T. I just assumed KINGOFCOINS had made the typo.
It appears to me that all the follow on posts are in reference to 213T not 231T.
[His images are for a 213T. I know nothing of a 231T]
I assumed everyone else also assumed he meant a 213T not a 231T & ignored the supposed typo.

[selldoor]

Re: Samsung 231T, recapped, no power, no lights

Ok - you will gather I have not read the history - its a bit like looking at pics of other boards.
Anyway there are two fuses on the Power supply board.
One is a white ceramic and the other is a Black Barrel
I can actually read that it is a T3.15A 250v.
Power off, meter on ohms 200 one probe on each end of fuse
or each fuse leg what do you get.- Should be the same as
touching the probes together.

[RalphSimon]

Re: Samsung 231T, recapped, no power, no lights

Those PS fuses are OK. 0 Ohm

However re-reading my initial post I should have clarified I was referring to the SMD fuses F51 & F101 that protect the FETs. Both appear open circuit

I have tested the 8 FETs

U52 & U54, U101 & U105 are short circuit
(The 4 furthest from the connector)

[selldoor]

Re: Samsung 231T, recapped, no power, no lights

I can see SMD F1 but cant make out the two you mention board numbers are too blurry. A good picture would help.
Is there no markings on them - Looks like there is something on F1 but cant read it
What are the part numbers on the fets.

[bluto]

Re: Samsung 231T, recapped, no power, no lights

Stop the madness. Its all laid out in my 213T thread. Basically what has transpired is that that the 4 220uf caps on the inverter have failed. The excess ripple causes one or more of the AO4600 MOSFETS to short out. This then causes the fuses to blow. So you need to replace the shorted MOSFETS (SMD can you handle soldering these?), replace the 4 220uf caps and any blown fuses on the inverter (4 amps). Also replace any bludged caps on the power supply while you are in there. I fixed over 30 of these a couple years back and they all came back to life.

[RalphSimon]

Re: Samsung 231T, recapped, no power, no lights

Hi Bluto.

To reiterate, (I have read your thread)
I have replaced the 6 caps on the PSB & 4 on the inverter board

I have now identified the 4 shorted MOSFETS U52 & U54, U101 & U105
& could buy some (obsolete) AO4600s off of eBay. Please advise if I should use a better, newer equivalent MOSFET. I note AO4619 (which you used) & AO4622 are listed as replacements, but even those seem obsolete / unavailable now! Am in UK.
As for my ability to (un/)solder them, time will tell. I have some braid & isopropyl alcohol

I have identified that the 2 SMD fuses F51 & F101 are open circuit, but am trying to discover their value so I can replace those too rather than jumper them.

Thanks.

[selldoor]

Re: Samsung 231T, recapped, no power, no lights

Hi Bluto.

I have identified that the 2 SMD fuses F51 & F101 are open circuit, but am trying to discover their value so I can replace those too rather than jumper them.

Thanks.

Bluto has now said they are 4 A fuses - these may be suitable
http://www.ebay.co.uk/itm/10-X-FUSE-...item3cca246825. It is sometimes easier to solder them on top of the
existing dead fuses rather than risk damage to the pads.

You could also check out the stock at farnells

http://uk.farnell.com/jsp/search/bro...D2031%2B204372

You will need to get the physical size right. some are 0603 and some 1206.

[bluto]

Re: Samsung 231T, recapped, no power, no lights

I might have some AO4619s left if you are unable to procure any. I think either is fine. I did not experience any issues using them alongside the AO4600s. I would practice removing some smds from a dead motherboard first. If you can't do it satisfactorily, then chipquik is definitely recommended to get the old ones off easier.

[RalphSimon]

Re: Samsung 231T, recapped, no power, no lights

Selldoor - Don't know how I missed Bluto's 4A info.

Bluto -Thank you for your most kind offer. However >

I have already bought on eBay (giorgio11185, China), package deal for 8 only of each, including delivery (8 of each to have some spares!)

10PCS AO4600 4600 SOP8 POWER MOSFET TRANSISTORS
Item number:390349008895 Sale price:US$5.00

10Pcs Littelfuse SMD 0603 4A 4 Amp Fuse
Item number:250896762299 Sale price:US$4.00

When I'm finished, if there are any left over... as a thank you to this board, anyone here can have them for free.

I'll update here as & when.