HP W2408H No Power (Surge) Repair - Success

[ryankam]

Customer brought in an HP W2408H 24 Inch wide screen lcd monitor. Customer said the monitor has no more power. He suspected it was due to a power surge. I opened the monitor, examined the power supply and noticed I was not getting any voltage on the secondary side of the power supply. I checked the Thermistor and found that it was only showing 3 OHMs of resistance which the specs for the NTC SCK 037 said it should had. Found out it should have been reading 5 OHMs when cool. Replaced thermistor with 5 OHM resistor and the monitor powered up. Removed thermistor, ordered SCK 037 part (NTC) replaced it. SG6902SZ (PWN/PFC) chip was now getting proper voltage and secondary now had standby power. Successfully powered up monitor. Not sure why it blew the thermistor instead of the varistor? Am I missing something?

Ryan

[macfun]

Re: HP W2408H No Power (Surge) Repair - Success

Customer brought in an HP W2408H 24 Inch wide screen lcd monitor. Customer said the monitor has no more power. He suspected it was due to a power surge. I opened the monitor, examined the power supply and noticed I was not getting any voltage on the secondary side of the power supply.Ryan

Hello, Ryan.

How did you open the monitor ?
I would open mine, due to noise inside (like a noisy cooling fan).
But did not see any screws after the 4 from the stand.

thanks

Philippe

[cmj21973]

Re: HP W2408H No Power (Surge) Repair - Success

Hello, Ryan.

How did you open the monitor ?
I would open mine, due to noise inside (like a noisy cooling fan).
But did not see any screws after the 4 from the stand.

thanks

Philippe

This might help you figure out how yours open.
Not the exact same one but, similar disassembly.

Use an old gift card, instead of a screwdriver, to pry the bezel off.

[macfun]

Re: HP W2408H No Power (Surge) Repair - Success

Waow, this great and exactly what I need to open it !!!

1000 thanks !!!

And obviously, there is no cooling fan inside ...
So I guess the noise is coming from one of the components.

I can check further on now, thanks to your help.

[AJH]

Re: HP W2408H No Power (Surge) Repair - Success

MANY THANKS, Just what I needed to know. Maybe I can access my USB connector and repair it.

[saferat10k]

Re: HP W2408H No Power (Surge) Repair - Success

Customer brought in an HP W2408H 24 Inch wide screen lcd monitor. Customer said the monitor has no more power. He suspected it was due to a power surge. I opened the monitor, examined the power supply and noticed I was not getting any voltage on the secondary side of the power supply. I checked the Thermistor and found that it was only showing 3 OHMs of resistance which the specs for the NTC SCK 037 said it should had. Found out it should have been reading 5 OHMs when cool. Replaced thermistor with 5 OHM resistor and the monitor powered up. Removed thermistor, ordered SCK 037 part (NTC) replaced it. SG6902SZ (PWN/PFC) chip was now getting proper voltage and secondary now had standby power. Successfully powered up monitor. Not sure why it blew the thermistor instead of the varistor? Am I missing something?

Ryan

i have the same issue with the monitor, the thermistor says 3 ohms on a test, which matches the info on:
http://www.mouser.com/ProductDetail/...bvgzTXCa9NLw==
do you have the power supply schematic so i can locate the varistor?
thanks, Jordan

[agie222]

Re: HP W2408H No Power (Surge) Repair - Success

Originally Posted by ryankam View Post
Customer brought in an HP W2408H 24 Inch wide screen lcd monitor. Customer said the monitor has no more power. He suspected it was due to a power surge. I opened the monitor, examined the power supply and noticed I was not getting any voltage on the secondary side of the power supply. I checked the Thermistor and found that it was only showing 3 OHMs of resistance which the specs for the NTC SCK 037 said it should had. Found out it should have been reading 5 OHMs when cool. Replaced thermistor with 5 OHM resistor and the monitor powered up. Removed thermistor, ordered SCK 037 part (NTC) replaced it. SG6902SZ (PWN/PFC) chip was now getting proper voltage and secondary now had standby power. Successfully powered up monitor. Not sure why it blew the thermistor instead of the varistor? Am I missing something?

Ryan

Ryan,

I also have that monitor and this one the power comes on the power light is blue BUT i get a pic for 1 -3 secs and then nothing blank/black pic. It seems as if some of the bulbs have burned out and I really like/love my monitor. Can you give me a suggestion on either what I can do to fix or where I can take it to fix it. TY

Adrianne

[budm]

Re: HP W2408H No Power (Surge) Repair - Success

@agie: It will help if you upload good clear pictures of the boards.

[blargg]

Re: HP W2408H No Power (Surge) Repair - Success

@agie: also, start a new thread, so that this one can be for ones that failed due to the thermistor.

[GameMaster1229]

Re: HP W2408H No Power (Surge) Repair - Success

Very late bump but I was browsing the web and found this forum as a solution for my HP W2408H monitor. My monitor appears to have no power what so ever but everything else is in good shape. Considering to crack it open and have a look at the power board side and replace the same exact SCK 037 part (NTC). I can barley find these parts on eBay in a 10 pack for $9 and from Taiwan. Hoping it will fix this nice monitor as I would enjoy to have it up and running again.

Also, as a first timer in basic repairs, how do you guys analyze and find out what parts need replacing for such situations for electronics? Any tips?

[kingwolf]

Re: HP W2408H No Power (Surge) Repair - Success

Alright so i have this monitor and im having this weird issue. i have these weird line distortions that are running through the monitor, i have like 3 lines going vertical and 1 going horizontal towards the top, you can really notice it when watching movies, not so much when playing games or browsing the web. Any info would be appreciative ^^

[vth]

Re: HP W2408H No Power (Surge) Repair - Success

Any other common issue on this PS? i checked the rectifier bridge and it gives random values on-board, while it tests correctly out of the board, anybody had issues with this? i checked the above mentioned thermistor but i also get datasheet results. Any other hint would help

[vth]

Re: HP W2408H No Power (Surge) Repair - Success

Solved!

Symptom: Completely dead, no standby light, nothing.

Solution: I replaced all caps and didn't work, so i checked Diodes and the larger one next to one inversor was giving bad readings in and out circuit ( .001 in both directions on multimeter diode mode), replaced it and monitor is up and running correctly.

[Porto]

Re: HP W2408H No Power (Surge) Repair - Success

I had this monitor also for nearly 7 year without problems.
I recently bought a 2nd hand HP2510i for 40 euro's because it wouldn't start up; after replacing some dpak mosfet and an SR26 diode it's working perfectly again.
I now use the 25" monitor because of its bigger screen.. image is identical to the HP w2408h... just plain and simple : BEAUTIFUL!

But my 2408h had the problem that when you turned it off, there was an audible, high frequency tone present, like a cap discharging or some transformer. If in standby mode, the tone is present but more high pitched. When the monitor was running there was no sound at all from it, quite weird.

[jamalC]

Re: HP W2408H No Power (Surge) Repair - Success

.. Replaced thermistor with 5 OHM resistor and the monitor powered up. ...Am I missing something?

Ryan

hello. im newbee and I have exactly the same problem with this screen. i only manage to find 4.7 or 5.6 oHm resistor, would that work?

cheers

[jamalC]

Re: HP W2408H No Power (Surge) Repair - Success

hello. im newbee and I have exactly the same problem with this screen. i only manage to find 4.7 or 5.6 oHm resistor, would that work?

cheers

ok i was a wee lazy. now i found a 5ohm, but there are so many: 30W, 10W, 25W, 2W etc.
im really puzzled which one would fit insteadof that thermistor, which was supposed to be 5ohm cold.
any help would be highly appreciated.

best regx

[Chungalin]

Re: HP W2408H No Power (Surge) Repair - Success

Correct me if I'm wrong, but varistors and thermistors are protection components against power line surges. For continued protection it's highly recommended to replace them, but for operational purposes they're are useless. A varistor can be just removed and the power supply will work the same. And a blown thermistor can be replaced by a wire bridge. This is for diagnostic purposes only.

[jamalC]

Re: HP W2408H No Power (Surge) Repair - Success

...For continued protection it’s highly recommended to replace them, but for operational purposes they’re are useless. A varistor can be just removed and the power supply will work the same. And a blown thermistor can be replaced by a wire bridge. This is for diagnostic purposes only.

so you mean I can safely remove this sck 037 thermistor and replace it with a wire to see if the screen will power up?

[Davi.p]

Re: HP W2408H No Power (Surge) Repair - Success

Probably yes, supposed you power on che monitor only one time, the NTC is there to protect the diode bridge from Power surge due to high current requested to charge the big cap the first switching on.

[budm]

Re: HP W2408H No Power (Surge) Repair - Success

SCK037: 15mm Dia.
At room temp (25c) the resistance is 3 Ohms (Zero power, no current flow), full steady state current is 7A Max at 25C, at this current flowing the resistance will drop down to 0.091 Ohms. It is NTC so as the temp goes up when the current start flowing its resistance will go down.