viewsonic vx2255wmb-2 2 seconds to black

[pookie21]

Hi to all you great people on this forum.
Firstly i turn on monitor and it flashes image then goes to orange.Did not try flashlight trick at this stage.Disassembled monitor and had visual inspection.I noticed high voltage ceramic caps c506 and c523 are burnt and have turned green(should be blue)and all caps looked ok. I ignored this and replaced caps X12 except 150/420v.
Reassembled and whilst connected to my pc turned on and now screen flashes but this time blue light remains constant.Yes i can see image with flashlight.Well i thought i had achieved something ?. Got monitor apart again now and am trying to identify parts and learn how to test.Firstly the 150/420v capacitor reads 137.7 capacitance is this acceptable ?. Cannot get one yet from parts store.Secondly the two high voltage ceramic caps c506 and c523 which i have removed give me no reading no matter what i try with multimeter? .The markings on ceramic are both 10p3kv.It is my first attempt at this so would appreciate any help from here.Have attached photo (same as) but not my photo .In the meantime i am reading through forum to get any knowledge that will help me. Max [email]sangwa2001@yahoo.com[

[budm]

Re: viewsonic vx2255wmb-2 2 seconds to black

Those are ballast caps for the lamps, very low capacitance, you need to check and see if it has any leakage resistance at all, your meter should show OL at the highest Ohm setting.
Do they all have 10p3kv printing on them?
It is 10pf 3000V, if it has resistance leakage, then the lamps will draw too much current which will cause the inverter to shutdown to protect itself.
When these caps start leaking, they will get hot and the body will have light brown color:
http://s807.photobucket.com/albums/y...nt%20FLX-3210/

Replacement cap:
http://www.mouser.com/ProductDetail/...ABWWD1BTwl8p83

These Viewsonic VX series have a lot of bad caps problem just like any other brand as you can see here.
http://s807.photobucket.com/albums/y...udm/VIEWSONIC/

The 150uf 420V, how good is the cap meter? can it also read ESR? You may want to replace it. If you have meter with TRUE R.M.S reading, then set to AC and read the AC ripple on that 150uF cap, it should be 1~2VAC or less.

[pookie21]

Re: viewsonic vx2255wmb-2 2 seconds to black

Thanks Budm for the quick reply.Have a Digitech qm1496 and all known good caps i check are within capacitance stated on caps.No sorry do not have esr meter. With the exception of the 150/420v which gives me 137.7 everytime. Do i test ballast caps off board? I have the repair manual and schematics but still trying to get my head round the info.
I will wait for reply before i unsolder ballast caps for testing.
thank you very much.Max

[budm]

Re: viewsonic vx2255wmb-2 2 seconds to black

Yes, test those ballast caps off the board, if you have doubt about them, I would replace them since they can cause damage to the inverter transformers. Your meter does not put out high enough voltage for really find out if the caps are bad for sure, but if you can read resistance with you meter which can only put out less than 10V, just think what will happen when those caps are exposed to 2000V in the circuits.

[pookie21]

Re: viewsonic vx2255wmb-2 2 seconds to black

Thanks again budm, my friend can locate the parts in question and i will replace them anyway.I will also do the tests you told me.I will let you know the results.

[pookie21]

Re: viewsonic vx2255wmb-2 2 seconds to black

Hi budm, just went to my local store and they only have 10nf3k .Mine are 10pf3k could i use them temporarily to see if any result.

[budm]

Re: viewsonic vx2255wmb-2 2 seconds to black

That is too much capacitance, it will let the lamps draw more current than they should, so the inverter may go into shut down.
10nF = 0.01uf
10pF = 0.00001uF
So that cap is 1000 time higher value than the original!

[pookie21]

Re: viewsonic vx2255wmb-2 2 seconds to black

Thank you budm. Will wait to get correct values. Bit annoyed that the salesman said yea they'll be ok mate. Max