Asus VH226H no power led

[plexico]

Ok. so this is my first Thread and I'm kinda new to actually trouble shooting circuits like this but i have read a lot of other post here and got the general basics down I think and so far i haven't seen a problems like mine.

so to start with whats obviously wrong with the board and that would be Resistor r605 I noticed it had been hot and i could read the markings so I opened the working monitor I have (matching set) and it should have been a 10k ohm resistor. checking it with a dmm I was reading about 25K ohms so i replaced it and its smoked up in just a few seconds.

What do you think could be causing this? I think its part of what you all call the start up circuit? correct me if im wrong.

what I have checked

voltage on main cap= 162v dc
Bridge rectifier = ok
checked esr of caps and all very close to specs i could find on there datasheets ( i know you this doesn't mean there all good because some are in parallel and the bad one wont show but im not worried about those at the moment)

Im a little rusty on checking mosfets so im not 100% sure on it but the values are not matching that of the working board also checking the ic for a short i am getting resistance between almost all the pins and thats not the case with the working board.

[budm]

Re: Asus VH226H no power led

Need to see good clear pictures of the bottom side of the board to see how this R605 is connected. One side of it may have low Ohm due to bad component.

[plexico]

Re: Asus VH226H no power led

Sorry about the pictures I only have a my cell phone. But from what I have gathered the only reason the resistor would burn out would be if the ic was shorted and this is a problem because i cant find a replacement. but I don't really know where to start a cross referencing one the ic is a TEA1530AP which should also be the same as a TEA1530AP/N2,112-ND but I can't find either.

[budm]

Re: Asus VH226H no power led

Ebay:
http://www.ebay.com/sch/i.html?_trks...at=0&_from=R40

[plexico]

Re: Asus VH226H no power led

Thanks do you think there's anything else i should test before i order this im not positive that's what it is, but I don't see how it could be anything else

[selldoor]

Re: Asus VH226H no power led

There is a bit of info about that IC in this thread (Different machine)
https://www.badcaps.net/forum/showth...0AP#post146494

Was the set yours when the fault developed may be there are other faults
you do not know or have not told us about. Some Asus are prone to bulb/wiring failure

[plexico]

Re: Asus VH226H no power led

it was mine I changed some display seting that caused it to go in to sleep mode and when it did it just went completely off and after that i discovered it didn't even have the standby power to light the led. but like i mentioned i have a pair of these and i swamped the know good board in to the other monitor and everything worked fine, i have had both since new and both plus a lg was all connected to the same outlet and computer when the fault occurred.,

[lexwalker]

Re: Asus VH226H no power led

it was mine I changed some display seting that caused it to go in to sleep mode and when it did it just went completely off and after that i discovered it didn't even have the standby power to light the led. but like i mentioned i have a pair of these and i swamped the know good board in to the other monitor and everything worked fine, i have had both since new and both plus a lg was all connected to the same outlet and computer when the fault occurred.,

The last time I find this type of symptom was due to a bad 5V rail, plus badcaps on that same rail. The monitor would suddenly go off whenever some menu setting was done, but then goes away after it has warmed up.

[budm]

Re: Asus VH226H no power led

Just measure the resistance between pin 8 (Drain) and pin 2 (GND), it will probably show low resistance. One end of r605 is connected to the main filter caps which as 160~170VDC on it. Are you sure that the old resistor was 10K?
This is the typical setup of the circuit.

[plexico]

Re: Asus VH226H no power led

Positive its a 10k ohm here's a picture of the resistor in the working board

checked the resistance between pin 2 and 8 and it starts at about 2k ohm and slowly continues to build resistance. checked the same on the working board and it shows completely open.

I went ahead and ordered the ic earlier this morning.

[plexico]

Re: Asus VH226H no power led

Im Happy to say after replacing the ic I am back in business the monitor on the left is the one that had problems.

Thanks for all the help guys

[selldoor]

Re: Asus VH226H no power led

Hi - That is great news - did you find an alternative IC or did you get the same from ebay?

[plexico]

Re: Asus VH226H no power led

Ordered a pack of 5 from china on ebay it was $11.00 but with 2 of these monitors figured wasn't a bad idea to have extras