Viewsonic lcd VA1912wb

[elbtax]

I was given the VA1912wb cause the green power light flashes off about every two secs. Screen is completely black. Checked with torch and see no image. Hooked to laptop and the os recognizes the monitor. Removed back cover and a 220uf,25v, 105c cap had the bottom blown out. Replaced all caps and checked solder joints on board. Soldered suspicious looking joints. When power applied the monitor exibits same problem as before. The fuse on the inverter board checks o.k. Any suggestions?

[elbtax]

Re: Viewsonic lcd VA1912wb

Forgot to add pics....

[tiggerific]

Re: Viewsonic lcd VA1912wb

I'm guessing the pictures are from before you recapped the board since there are 3 caps definately bulging. The 4 chips near the transformers seem to have undergone a fair bit of thermal activity. One or more might be toast.

[elbtax]

Re: Viewsonic lcd VA1912wb

Thanks for the reply tiggerific. These pics are before the recap as you surmised. I started re-capping about a month ago. Someone gave me a 19" Gateway tft fpd1960 that the screen flashed with the Win logo and went off. The power light stayed green. Replaced caps & put a "touch" of solder around inductor joints. Works fine now. Also recapped an Acer S58m mobo. Works fine now. Anyway, can't do a lot with only a solder iron and a Dig MM.

Thanks for your reply....

[Krankshaft]

Re: Viewsonic lcd VA1912wb

I second to check those IC packages.

They are probably driver transistors in a DIP package.

Go to alldatasheet.com enter the part number on them and get the pinouts.

Using the diode checker of your DMM should reveal any open shorts in the transistors.

[elbtax]

Re: Viewsonic lcd VA1912wb

Thanks for the reply KS. I will check for the pin-outs. I feel the problem is something simple i am missing. Hope so anyway..
Thanks again..

[elbtax]

Re: Viewsonic lcd VA1912wb

I must be an idiot..I can't find the datasheet for the pin-outs. The chip has an A with a long right leg with a circle going around it from the short left leg. (Mfg?) Then it says P605 and underneath that BD6E1P. I do think these are transistors as you said KS. I think they control voltage to the transformers maybe. Anyway. Will keep searching.
Thanks for the input. I am steady learning new things about these inverters even if i don't get it repaired. That is invaluable.

[elbtax]

Re: Viewsonic lcd VA1912wb

I have been searching on this inverter board and can find nothing. It is a Delta board,A190E2, DAC-12M030A, Rev1F. Have found 12M030 - disc & 12M030B Rev 0F. This must be a newer type inverter..

[tiggerific]

Re: Viewsonic lcd VA1912wb

Believe I found them - P605 => http://pdf1.alldatasheet.com/datashe...D/AOP605L.html

CE mode mosfets (1xN & 1xP) in each package so it's quite possible they have gone bad.

[elbtax]

Re: Viewsonic lcd VA1912wb

Thanks Tiggerific,
Had to take a break for awhile. Went fishing. Caught some nice bass & bream.
I had pulled up the P605 but didn't get to the right one. This datasheet looks just like the chips. Thanks again. BTW, i found some more bad joints with my magnifier. Wouldn't cut off with the switch before. Will now. I think progress is being made.
Thanks again....

[elbtax]

Re: Viewsonic lcd VA1912wb

checked the pin-outs on the chips and found no shorts. (IF i did the test correctly.) There is a fuse ,5a,250v, in front of the small cap near the chips., F200, but it checks o.k. On the board there is a notation to replace with correct fuse type and rating. (F101). Is this the type fuse are is there another fuse somewhere? Went over the board with magnifier and can't find another fuse...Looked for a pico fuse & found nothing. I know i am not getting power to the x-formers. Any more suggestions?

[Krankshaft]

Re: Viewsonic lcd VA1912wb

The other fuse is right behind the IEC line cord connector in that round package.

The first time I saw these fuses they were in crappy Delta (go figure) Xbox power supplies.

Most companies use glass or ceramic fuses with axial leads soldered to them.

But Delta seems to prefer these fuses.

[elbtax]

Re: Viewsonic lcd VA1912wb

Thanks KS - Haven't been on the site lately. Just got my internet back. Bad storm on Wed knocked out everthing. Killed my wireless modem also. The F200 fuse is of the glass type with axial leads. It checks o.k.

[elbtax]

Re: Viewsonic lcd VA1912wb

Found it.. Checks out ok. I think i will go ahead and replace the two fuses anyway. Got nothing to lose but time & a little money. I am retired and it gives me something to do. Thanks for everyones time and advice.

[elbtax]

Re: Viewsonic lcd VA1912wb

After extensive research and testing - two of the dip switches are toast...These are the AOP605 chips. Checked with Mouser. No comparable chip. Does anyone know where i can get these chips besides HK, China, or Taiwan? Maybe Fairfield? Will keep checking. Thanks for all of your input.

[truename]

Re: Viewsonic lcd VA1912wb

elbtax, what dip switches are you referring to? Where are they at on the board?

[elbtax]

Re: Viewsonic lcd VA1912wb

The ones that are in the "dark" area of the board that is in posting #2. They are the dips that give power to the x-formers. They are actuall mosfets. Alpha Omega P605 w/N&P channels.

[elbtax]

Re: Viewsonic lcd VA1912wb

UPDATE: After searching Digi-Key, Mouser, Fairchild, etc. on the web, i finally found the mosfets at Blue Star International at $6.99 each. Not cheap. Ordered and will be here soon. Coming from Huntington, N.Y.

[dan8139]

Re: Viewsonic lcd VA1912wb

Good Luck!

[sonicdrive]

Re: Viewsonic lcd VA1912wb

any luck on this repair ?? i have the same problem