Proview PL926WBi No Power

[delaware74b]

I was 'gifted' with this monitor that had no power complaint. Ooened it and found it full of Xunda caps, replaced the 220 uF and 470 uF with panasonic FC series caps. Still has no power indicator, however the +14 and +5 VDC supplies are working, both with and without the logic board connected. My questions are: is there a way to override the BLON to trigger the backlights and does it sound like a logic board problem? BTW- C215 and C216 were removed so I could fix another monitor that had 6 bad caps. More are on order from DK

[PlainBill]

Re: Proview PL926WBi No Power

I was 'gifted' with this monitor that had no power complaint. Ooened it and found it full of Xunda caps, replaced the 220 uF and 470 uF with panasonic FC series caps. Still has no power indicator, however the +14 and +5 VDC supplies are working, both with and without the logic board connected. My questions are: is there a way to override the BLON to trigger the backlights and does it sound like a logic board problem? BTW- C215 and C216 were removed so I could fix another monitor that had 6 bad caps. More are on order from DK

IIRC, you can trigger the backlights by grounding the BLON line. Do this only with the CCFLs hooked up!! They would be at minimum brightness, but you can use a voltage divider (2 resistors in series) to pull the brightness line up.

PlainBill

[delaware74b]

Re: Proview PL926WBi No Power

Thanx PlainBill, I'll give it a test once I get the remaining caps from DK

[delaware74b]

Re: Proview PL926WBi No Power

I just installed the new caps in this monitor and it is definitely a problem in the logic board. I can't justify the $ in repairing or replacing the logic board on a monitor that cost me nothing.

[junkmansam]

Re: Proview PL926WBi No Power

Sorry to hear that. I'm a newbie when it comes to LCD monitors and so far I'm 1 for 1 in that a fixed a Viewsonic VA1912wb that started the early stages of bad cap itis. Purely beginers luck. A lot has to do with what stage the cap failure mode the monitor is in when you get it. My Viewsonic was exhibiting white horizontal lines floating upwards. I've yet to bring a monitor back from complete darkness.

Sounds like you are far more technically advanced than I am but I was wondering if the logic board became faulty because of bad caps or did it have a seperate component failure on the logic board itself that caused the problems.

[delaware74b]

Re: Proview PL926WBi No Power

There is no doubt in my mind the bad caps caused damage to the logic board. All the 470 uf and 220 uf caps on the power supply/inverter board were swollen. That allowed ripple current into the logic board. I had +5 and +14 at the logic board that had very little ripple after recap. FWIW, I have successfully an envision 19" LCD and a compaq evo d510 sff and have one another awaiting my time for recap.

[junkmansam]

Re: Proview PL926WBi No Power

PlainBill really knows the in's and out's of these things. He helped me imensely.

This website is great. I plan on sticking around for a long time. Great reading these help threads.

Let us know how your next project goes. Good luck

[EGuevarae]

Re: Proview PL926WBi No Power

I was 'gifted' with this monitor that had no power complaint. Ooened it and found it full of Xunda caps, replaced the 220 uF and 470 uF with panasonic FC series caps. Still has no power indicator, however the +14 and +5 VDC supplies are working, both with and without the logic board connected. My questions are: is there a way to override the BLON to trigger the backlights and does it sound like a logic board problem? BTW- C215 and C216 were removed so I could fix another monitor that had 6 bad caps. More are on order from DK

So you have no green / power led, or have the led on but no backlights? I'm kinda confused, and since I've dealt with that PSUs before, I need more info to see if I can help you.
I guess you have already tested F202, right?

[delaware74b]

Re: Proview PL926WBi No Power

I have good +5 and +14 volts going into the logic board. I have no power LED either blue or orange, the backlight isn't lighting when i try to pull up with +5v through 1k resistor or grounding the BLON. I can faintly hear the inverters high frequency drive when i apply the power. All fuses test good on the inverter board.

[EGuevarae]

Re: Proview PL926WBi No Power

I have good +5 and +14 volts going into the logic board. I have no power LED either blue or orange, the backlight isn't lighting when i try to pull up with +5v through 1k resistor or grounding the BLON. I can faintly hear the inverters high frequency drive when i apply the power. All fuses test good on the inverter board.

5V go to the logic board, and then return to the inverter section of the PSU/inv board via the BLON pin. I remember feeding 5v in the BLON pin of a 700P to turn on the CCFLs, but then I remember that PCBONEZ said it was not a good Idea (or it was PlainBill.....). Did you check the panel buttons/board to see if they are OK? if the ON/Off button/switch is bad you won't turn on that thing never. I will try to look to see if I have a Proview board for a 19" (with 14v input instead of 12 like the 15 & 17 versions) and I will check into it.