Viewsonic VA2010wb (flashing screen)

[sabre504]

Re: Viewsonic VA2010wb (flashing screen)

Hi i will check that tomorrow am off to sleep gotta work in morn
Thanks

[sabre504]

Re: Viewsonic VA2010wb (flashing screen)

Hi yes it is i get continuity to all 4 corners

[budm]

Re: Viewsonic VA2010wb (flashing screen)

That voltage for U3 input is generated by that U6 AAT1164 chip above that inductor, you can down load the spec of that chip and start checking the voltages on those pin.
http://www.alldatasheet.com/datashee...164C-Q5-T.html

[sabre504]

Re: Viewsonic VA2010wb (flashing screen)

Hi
no power to U6 at all .

On picture i have attached

ZD1 is pulsing 0-3.1v
ZD4 is pulsing 4.56-4.62v
R24 is pulsing 4.56-4.62v

Also rechecked the psu with no load 5v output is steady at 5.21v
but in picture of psu the jumper ringed in green shows 11.8v no load but when connected to the screen it fluctuates betwwen 12.01 and 12.33v .

Cannot borrow the supply i originally used to test as it appears it is not working so maybe my supply still has a fault so am going to change the
dm0565r green mode power transistor (one of the few bits not been replaced yet ) and then go from there

[selldoor]

Re: Viewsonic VA2010wb (flashing screen)

Have you checked D5 and also R41 despite a number of people telling me no
I am sure I once read that 0 rated resistors could be used as fuses.

[selldoor]

Re: Viewsonic VA2010wb (flashing screen)

While your at is are Tvs1 & 2 surge protection resistors - they seem to go in bigger versions stopping sets from working but allow it to work when they are removed.
(dont really understand how that works)

[sabre504]

Re: Viewsonic VA2010wb (flashing screen)

Hi Selldoor i have seen it once on a board in a TV 0ohm in F1 and it looked factory fit but i wouldnt like to argue the case .

I will check those parts later when kids are in bed and i get some peace

[ben7]

Re: Viewsonic VA2010wb (flashing screen)

Hi Selldoor i have seen it once on a board in a TV 0ohm in F1 and it looked factory fit but i wouldnt like to argue the case .

I will check those parts later when kids are in bed and i get some peace

If you find that R41 is still OK, try removing it, and see if the switching smps comes up to voltage.

Also, those mlcc's do go short sometimes, perhaps one of them (C47,48,49,50,51) is bad.

[sabre504]

Re: Viewsonic VA2010wb (flashing screen)

Pulled D5 off the board and measures ok .

R41 ok no difference when not in line to PSU .

C47-51 all measure the same so assume ok .

Changed dm0565r still the same issue .

The Tvs not sure what they are so just checked them on resistance and they all measure the same too .

Also reflowed the whole of the board just in case any bad joints .


I now have laid the whole thing out on my bench and connected it all together and have noticed that the inverter trans is buzzing in sync to the power going up and down ,whether that is because the power is fluctuating or thats whats causing it i am not sure.

[selldoor]

Re: Viewsonic VA2010wb (flashing screen)

Still seems odd there is nothing in that whole area. I'd test R166 as a fuse then with the power on see what voltage was on every test point in that part of the board.
Did you diode test the two zeners.

[sabre504]

Re: Viewsonic VA2010wb (flashing screen)

Hi all
well still not got any futher with this as had to put it to one side for a while .

Thought i would check all the ic chips but cant find any spec sheets for
U8
PS25LV010
EO553
CN1FJW

or U10
L32
6T74W

Wondered if anyone had an idea or dealt with them before
Other ic's i have if i need to replce them

[retiredcaps]

Re: Viewsonic VA2010wb (flashing screen)

PS25LV010

Likely serial flash.

http://www.alldatasheet.com/view.jsp?Searchword=25LV010

[Duncanbest]

Re: Viewsonic VA2010wb (flashing screen)

U10 is a eeprom (BR24L32).

Outlook is like
http://www.ictradenet.com/BR24L16F-WE2/

data-sheet

http://www.rohm.com/web/global/produ...ct/BR24L32FJ-W

[sabre504]

Re: Viewsonic VA2010wb (flashing screen)

Hi thanks for the pointers
U10 and U10 are both getting voltage in at a steady 3.2v and i cannot find any shorts .

Managed to find a sheet for the main logic ic controller and think this may be the problem as 3.3v are going in but the outputs fluctuate from 0 - 3.2v and should be at 3.3 steady

[sabre504]

Re: Viewsonic VA2010wb (flashing screen)

I have removed the large chip U7
Now the screen and power are no longer pulsing .
Not to say this is the problem but until new chip turns up in a couple of weeks and fitted (again ordered from Hong Kong as cant get here ) will have to see what happens from there .
So yet another job in the attic awaiting parts