Hyvision by Megavision MV220 LCD monitor goes blank after 0.5-1 second

[bobioni]

I believe I have a bad capacitor based on its appearance and the aforementioned title. When installing the new capacitor, I realize the capacitor terminals are different lengths to differentiate positive from negative. Can you tell me which terminal goes to the ballast side and vice versa? Below is a link to the exact inverter board



https://www.badcaps.net/forum/attach...4&d=1389598177

[stj]

Re: Hyvision by Megavision MV220 LCD monitor goes blank after 0.5-1 second

forget the wire length, the negative side is marked on the plastic sleeve.

[bobioni]

Re: Hyvision by Megavision MV220 LCD monitor goes blank after 0.5-1 second

I have already identified the positive & the negative capacitor terminals. On the surface of the inverter board are now two holes from which the old capacitor was desoldered & removed. The interior hole (closest to the ballast/transformer) has a blue ring around it, whereas the exterior ring (closest to the edge of the inverter board) DOES NOT have any colored ring around it. Which of these holes is for positive & which is for negative?

[selldoor]

Re: Hyvision by Megavision MV220 LCD monitor goes blank after 0.5-1 second

You put it in the same way as the old one came out?
The Blue Ceramic caps do not have polarity.

As you can see in YOUR picture the stripe on the side
faces the edge of the board so just put the new one in the same way.
copy off YOUR picture?

[bobioni]

Re: Hyvision by Megavision MV220 LCD monitor goes blank after 0.5-1 second

That pic is what the inverter board should look like. That pic was borrowed from a post in January 2014; a member who had an identical problem. My capacitor had burst/exploded and was non-recognizable. I'll take your advice and line it up as in the picture, but from an educational perspective, I'd still like to know the positive/negative relationship with respect to the holes in the inverter board as requested earlier.

[selldoor]

Re: Hyvision by Megavision MV220 LCD monitor goes blank after 0.5-1 second

Post pictures of the top and bottom of your board

[bobioni]

Re: Hyvision by Megavision MV220 LCD monitor goes blank after 0.5-1 second

Attached is a pic of my inverter board (top & bottom) with the capacitor removed. The arrow points to the inverter board hole with a blue ring around it. Which capacitor lead goes to the hole with a blue ring, positive or negative?

[addytzu123]

Re: Hyvision by Megavision MV220 LCD monitor goes blank after 0.5-1 second

Hi,
The top hole is for negative lead and the one where your arrow points is positive.
As you can see, from the bottom, the positive lead of the capacitor is linked to pin 17 of the FAN7311 , wich is Vin.

[selldoor]

Re: Hyvision by Megavision MV220 LCD monitor goes blank after 0.5-1 second

That is correct - however if you had posted the picture with the query it could have been answered straight away.
See the white box where the cap is positioned, it has a broad white line down one side- That line indicates which side is negative.

[bobioni]

Re: Hyvision by Megavision MV220 LCD monitor goes blank after 0.5-1 second

Thanks to all for providing this micro-electronic beginner the needed insight. I will update status upon completion.

[bobioni]

Re: Hyvision by Megavision MV220 LCD monitor goes blank after 0.5-1 second

Okay, I replaced the inverter board capacitor; unfortunately, the same "2 seconds to black" exists. With the monitor on & a flashlight in hand, I can in fact see the Windows log in desktop , confirming the "2 seconds to black". I was able to secure a known-working inverter board and replaced the "faulty inverter board"; same result, "2 seconds to black". Is it accurate to assume at this point, that the CCFL bulb(s) are suspect?

[stj]

Re: Hyvision by Megavision MV220 LCD monitor goes blank after 0.5-1 second

or the wires on them.

[bobioni]

Re: Hyvision by Megavision MV220 LCD monitor goes blank after 0.5-1 second

Okay. The wires are intact. Does anyone know a good source for CCFL bulbs? Is it also possible to substitute LED lights for the CCFL bulbs in the event the CCFL bulbs might not be available?

[lexwalker]

Re: Hyvision by Megavision MV220 LCD monitor goes blank after 0.5-1 second

Okay, I replaced the inverter board capacitor; unfortunately, the same "2 seconds to black" exists. With the monitor on & a flashlight in hand, I can in fact see the Windows log in desktop , confirming the "2 seconds to black". I was able to secure a known-working inverter board and replaced the "faulty inverter board"; same result, "2 seconds to black". Is it accurate to assume at this point, that the CCFL bulb(s) are suspect?

If that 2 seconds to black still exist then there could be other factors causing it. Have you checked the resistance of both transformers on the secondary/output side? Also do check for failed MOSFETs (which looks like I.Cs).

[bobioni]

Re: Hyvision by Megavision MV220 LCD monitor goes blank after 0.5-1 second

Being a beginning knowledge seeker, I'm not quite certain what MOSFETs are. Are the MOSFETs as well as the transformers located on the inverter board? If so, I did mention that I swapped out the questionable inverter board for a known working inverter board. The known working inverter board was removed from a TV which I watched yesterday; so I know the inverter board functions.

[lexwalker]

Re: Hyvision by Megavision MV220 LCD monitor goes blank after 0.5-1 second

Being a beginning knowledge seeker, I'm not quite certain what MOSFETs are. Are the MOSFETs as well as the transformers located on the inverter board? If so, I did mention that I swapped out the questionable inverter board for a known working inverter board. The known working inverter board was removed from a TV which I watched yesterday; so I know the inverter board functions.

Whoops! My bad... Missed this part...

I was able to secure a known-working inverter board and replaced the "faulty inverter board"; same result, "2 seconds to black". Is it accurate to assume at this point, that the CCFL bulb(s) are suspect?

Yups, there is the possibility of bad CCFLs in that LCD panel. Anyway, are both inverter boards the same one? If the inverter board is different (and driving lamps of different specifications) then it could also produce that 2 seconds to black. However if both are the same inverter boards, then a very high likelihood that one (or more) lamps are bad. You can test which lamps by hooking both panels up on that single inverter board (by swapping the lamp connections between both panels), though a large table will be required to accomodate them...

[stj]

Re: Hyvision by Megavision MV220 LCD monitor goes blank after 0.5-1 second

Okay. The wires are intact. Does anyone know a good source for CCFL bulbs? Is it also possible to substitute LED lights for the CCFL bulbs in the event the CCFL bulbs might not be available?

yes to both questions.
http://stores.ebay.com/lcd-led-parts

[bobioni]

Re: Hyvision by Megavision MV220 LCD monitor goes blank after 0.5-1 second

Yes, both inverter boards are MV179; thanks for confirming my suspicions regarding a bad CCFL; will proceed to test lamps today.

[stj]

Re: Hyvision by Megavision MV220 LCD monitor goes blank after 0.5-1 second

make a note of the tube diameter,
and the total length including the metal frame it sits in,
you will need that info to order new tubes/led kit

[bobioni]

Re: Hyvision by Megavision MV220 LCD monitor goes blank after 0.5-1 second

"Anyway, are both inverter boards the same one? If the inverter board is different (and driving lamps of different specifications) then it could also produce that 2 seconds to black," to answer lexwalker (sorry, haven't figured out yet how to quote another forum member)

Yes, both inverter boards are MV179; thanks for confirming my suspicions regarding a bad CCFL; will proceed to test lamps today.