Acer P193w - blink screen

[spintop]

Re: Acer P193w - blink screen

Sounds like you are getting to the 'test CCFLs and wiring' part.Perhaps try one light on at a time...eg the top ones first and see if they come on at all, then try the bottom the same way.The majority of times I have the fault on this model, its usually the top lamp that fails,but you can get the monitor fault where either top or bottom does not light at all,so making it a component type fault.

U are right on ! absolutely correct !!!
See top post, faulty top ccfl !!

So did u try to replace the tube ? pls advice how to go about diassemble to reach the tube

[spintop]

Re: Acer P193w - blink screen

Today I try something else, there are 4 CCFL connectors in this Acer P193w.
Hook up 1 (topmost) to a spare 11" laptop panel, and the 3 remain hook to this acer panel.

Result:
- Great ! blinking resolved, and the image on screen is good except only 3/4 the brightness having only 3 CCFL powered.
- Same result if i hook to the 2nd connector.
- But with the 3rd and 4th (bottommost), blinking comes back.

Questions:
- Can I conclude top 2 CCFL tube faulty ?
- Bottom CCFL is ok ?
- Is it easy to buy and replace the CCFL ?
- Is there a way to trick the sensing circuit to just use 3 CCFL tubes ? Because with all 4 coonected, the sensing circuit kicks in and switch on and off (blinking). I can do with the brightness of 3 tubes, just that i have the 11" panel ON and hanging.

[Rtech]

Re: Acer P193w - blink screen

Sounds like you are getting to the 'test CCFLs and wiring' part.Perhaps try one light on at a time...eg the top ones first and see if they come on at all, then try the bottom the same way.The majority of times I have the fault on this model, its usually the top lamp that fails,but you can get the monitor fault where either top or bottom does not light at all,so making it a component type fault.

[spintop]

Re: Acer P193w - blink screen

Try taking a picture of that big 100uF suscon from an angle you see it's top if it's slitghtly bulged. Had similar symptoms with LG after replacing small caps. Eventually it was the big one.

Voltage at the big cap is stable at 330V.
I try change it with a new spare cap, did not solve the problem.

[spintop]

Re: Acer P193w - blink screen

With the power off, try checking the resistance of the inverter secondaries. The difference between the two should be no more than 3%.

I am not sure if i measured correctly, inverter transformer: secondary leads 517 ohms for both transformers.

See the diagrams, 517ohms between the 2 green point and also same value at the 2 red point

Is value too low ?

[spintop]

Re: Acer P193w - blink screen

Did you test the ESR on the caps? They can be bad without bulging, and those don't look like good brands. The solder on T502 looks nasty, but it could be the picture or just lead-free solder.

I did not test the ESR. Understand that they can be bad, but the voltage output at the filter caps are stable 5V and 14V

Solder is lead-free, I will re-touch all the solder leads again.

[CapBlown]

Re: Acer P193w - blink screen

Try taking a picture of that big 100uF suscon from an angle you see it's top if it's slitghtly bulged. Had similar symptoms with LG after replacing small caps. Eventually it was the big one.

[jetadm123]

Re: Acer P193w - blink screen

With the power off, try checking the resistance of the inverter secondaries. The difference between the two should be no more than 3%.

[jsog]

Re: Acer P193w - blink screen

Did you test the ESR on the caps? They can be bad without bulging, and those don't look like good brands. The solder on T502 looks nasty, but it could be the picture or just lead-free solder.

[spintop]

Issue: when switch ON, the screen blink very quick showing "Acer", and black screen, and the power LED also blink from orange to blue.

Open up the monitor

- No bad cap
- With connectors remove from logic board and CCFL, the power board has stable voltage of 5V and 14v
- On the back of PSB, the U501 & U502 Mosfet (9962GH) no short (measured the leads desoldered from board)
- IC501 i believe is inverter controller, part (MPS 0805, MP1008ES). Can't find the datasheet online
- Inverter transformer: secondary leads 517 ohms for both transformer

I am thinking of opening up the CCFL backlight to see if the problems lie in there.

Any advice before i proceed further ?
thanks