Proview PL926Wbi - recapped, same shut off issue

[Wyld_Goose]

Re: Proview PL926Wbi - recapped, same shut off issue

Well done - so does that mean the second set is working correctly?

Yup, powers up and is as good as gold. Funny how in both cases, it was the bulbs and not the caps. (not that changing them out for good ones didn't hurt) I just want my old fashion monitor powered by a hamster and wheel. Wheels needed a little WD-40 and hampsters just needed to be fed, and were cheaply replaced if they died.

[selldoor]

Re: Proview PL926Wbi - recapped, same shut off issue

Dunno about replacing an LCD panel or if it's even worth it.

Probably not unless you can pick a working one up cheap where the
set has another problem.

I might as well use good bulbs from the first monitor to get the second one working.

Good Plan

I successfully took a good bulb from the first and replaced the bad bulb in the 2nd. Not fun.

Well done - so does that mean the second set is working correctly?

So in researching CCFLs, it seems just like with some of the bad caps out there, it's not a matter of if, but when CCFLs start to die. And when they do start to die they tend to draw more voltage in from the inverter and can tear it up bad, especially if there are crappy caps on it.
I had two thoughts on this. One being a question of: Would it not be smart to replace all caps with a slightly higher voltage ratings, knowing that CCFLs will start to die within 2-4 years?

Bulbs do have a life span seems to vary from 10000 hours to 20000.
Replacing the caps on the inverter board with higher voltage may give a cleaner supply and give them a longer life.

And the second, because CCFLs will die, would it not be better if your going for a new monitor to just bite the dollar bullet, and go LED? Seems like the extra cost will pay for itself in the long run.

Yes and No - seems a good idea but what is the life span of a led?
I still dont think that it is proven and the cynic in me suggests monitor manufacturers are not working to give you a set that will last any longer.
We have seen a few cases on here where LED sets go wrong and we have been unable to bottom out what the problem was.

Tough luck on Monitor 1

[retiredcaps]

Re: Proview PL926Wbi - recapped, same shut off issue

I take a ccfl that I have leftover. And I plug it into the connector with the bad bulb. Then I find a spot on the lcd panel that is flat and will fit the bulb, and I tape it down. And cover it with duct tape. The entire length of the bulb. By having the 4th lamp lit the monitor now stays on full time.

Hmm, interesting idea.

We have seen some members try to fool the inverter pwm with a capacitor, resistor and other components, but never the above.

[Wyld_Goose]

Re: Proview PL926Wbi - recapped, same shut off issue

What I have learned:
LCD panel corners are easy to crack when the light goes out in the workshop just as your separating the screen case, an you attempt to set it back down carefully, and the corner just catches the edge of the case and doesn't want to support the weight of the entire panel. Needless to say the original monitor I've been working on here is screwed.
Dunno about replacing an LCD panel or if it's even worth it.

I've learned the working with CCFLs sucks! I turned to working on the 2nd monitor and figured at this point, where I was going to buy new CCFLs I needed to replace in both of them, I might as well use good bulbs from the first monitor to get the second one working.

I successfully took a good bulb from the first and replaced the bad bulb in the 2nd. Not fun.

So in researching CCFLs, it seems just like with some of the bad caps out there, it's not a matter of if, but when CCFLs start to die. And when they do start to die they tend to draw more voltage in from the inverter and can tear it up bad, especially if there are crappy caps on it.

I had two thoughts on this. One being a question of: Would it not be smart to replace all caps with a slightly higher voltage ratings, knowing that CCFLs will start to die within 2-4 years?
And the second, because CCFLs will die, would it not be better if your going for a new monitor to just bite the dollar bullet, and go LED? Seems like the extra cost will pay for itself in the long run.

[Wyld_Goose]

Re: Proview PL926Wbi - recapped, same shut off issue

Thank you. I'm now wondering what is going to be more difficult. Checking/Changing out CCFL tubes for the first time, or finding somewhere in my house without dog hair. lol

Again. Thanks. I will attempt to keep updated on success or failure.

[Lumberjack777]

Re: Proview PL926Wbi - recapped, same shut off issue

There is another option you could use, that I have never shared with this forum.
I sometimes do repairs for people and I get a bad ccfl. When I tell them the amount I'll need to charge to replace a single lamp, they would rather junk the monitor and buy a new one. So I give them this option instead.
I take a ccfl that I have leftover. And I plug it into the connector with the bad bulb. Then I find a spot on the lcd panel that is flat and will fit the bulb, and I tape it down. And cover it with duct tape. The entire length of the bulb. By having the 4th lamp lit the monitor now stays on full time.
The lamp used can be a little smaller. And you can often find them at a local electronics recycling center for a few bucks. Or taken from a scrap lcd monitor.
Three bulbs is usually plenty of light for the monitor to be useful. And the diffusing technology of the plastic distributes the the light fairly evenly over the entire lcd screen.

[Lumberjack777]

Re: Proview PL926Wbi - recapped, same shut off issue

Ok I now know what bulbs are bad. On the 1st monitor, the one this thread is about, I definitely know 1 that is really bad. (Made the 2nd monitor screech and fritz), and am a little suspicious of a 2nd bulb on the first monitor. I know which bulb is bad on the 2nd monitor. OK! Small steps to success. (little happy dance)

Ok sensei, now what?

Ok good. You've narrowed it down to the ccfl. A place a lot of people out here recommend is CCFL Warehouse http://www.ccflwarehouse.com/

Hopefully its just a bad wire connection. Then you won't have to buy anything.

You'll need to strip it down to just the LCD panel. Then the outside edge pieces unlock and pry loose. Sometimes little screws have to come out in places. Be very careful with the board that connects to the plastic that goes inside the lcd screen.
You'll pry off a plastic piece around the edge (normally) and the lcd screen will be loose. Don't let it drop out. Then you'll get to some plastic sheets (diffuser sheets). Make sure those stay in the exact same order for reassembly. Then to the thick plastic plexiglass. The ccfls will be on the top and bottom. You may have to pull it out a little to release the bulbs.
Then you need to pry the end cap off the bad bulbs. Check for broken wires here. It might just be a bad soldering connection. If the bulb(s) are cracked or bad you'll have to order some new one(s). You'll need to measure the length and the diameter of the ccfl and put that in your order from ccfl warehouse. http://www.ccflwarehouse.com/tutorials.html
You can also call them and talk to them and maybe they can help with the measurements.
Just follow those tutorials I just posted. Then you put it all back together again carefully.
You want to perform this in a dust free room with no pet hair also. Anything that could stick to the plastic diffuser sheets.
The best thing is to go slow. Take your time. Good luck grasshopper.

[Wyld_Goose]

Re: Proview PL926Wbi - recapped, same shut off issue

Ok I now know what bulbs are bad. On the 1st monitor, the one this thread is about, I definitely know 1 that is really bad. (Made the 2nd monitor screech and fritz), and am a little suspicious of a 2nd bulb on the first monitor. I know which bulb is bad on the 2nd monitor. OK! Small steps to success. (little happy dance)

Ok sensei, now what?

[Lumberjack777]

Re: Proview PL926Wbi - recapped, same shut off issue

OK. With a good bulb plugged in. You try each connector. When you plug it into the one with the bad bulb. It will stay lit. That means that's the one with the bad bulb.

And right. Try testing them with another bulb in case you used a bad bulb from the broken monitor to test with.

If it does turn out to be a bad ccfl, then we can go from there. Replacement takes a lot of patience.

[Wyld_Goose]

Re: Proview PL926Wbi - recapped, same shut off issue

ok that's what I'm working on now. Correct me if I'm in error.
I have both monitors next to each other. The 1st monitor has 3 of the 4 ccfl connected to the inverter board.
The second is not connected to it's board at all. I am connecting 1 of the ccfl connectors from the 2nd monitor to the 1st inverter board (the 4th spot).

Fire it up. If it doesn't work, turn off, wait a minute, disconnect ccfl connection from 2nd monitor and move it to then next connection up on the first monitor. (say the 3rd slot this time) Then replace the 4th slot with the 4th connector from the 1st monitor.
(the 2nd monitor connection i used might be to a good or bad ccfl. just because it didn't work doesn't mean it was a bad bulb)
repeat. do this for all 4 connections. if none work, I can assume I picked a bad bulb from the 2nd monitor. and repeat all the steps with another bulb connector from the 2nd monitor.


Sound right?

If I have to change out bulbs, do you know of a good video on how it's done? I'm not finding anything good on youtube. I may be using the wrong search for it

[Lumberjack777]

Re: Proview PL926Wbi - recapped, same shut off issue

I've got a 2nd monitor that I'm working on, but to seems to have the same problem. There is always my wife's monitor that works. hmmmmm

So if 1 CCFL is bad, all 4 will shut off?

(has breaking a wife's monitor in the process of checking for a bad CCFL ever been used as grounds for divorce before?)

Hahaha. And nah, it won't break them. I mean, you are just borrowing them for a few minutes right?

You could use your spare. You just have to locate a good bulb. You have a 3 out of 4 chance.

And yes, just one bad ccfl kicks in the protection (feedback) circuit and the monitor shuts them all off.

It's looking more and more like you have a bad ccfl.

[Wyld_Goose]

Re: Proview PL926Wbi - recapped, same shut off issue

I've got a 2nd monitor that I'm working on, but to seems to have the same problem. There is always my wife's monitor that works. hmmmmm

So if 1 CCFL is bad, all 4 will shut off?

(has breaking a wife's monitor in the process of checking for a bad CCFL ever been used as grounds for divorce before?)

[Lumberjack777]

Re: Proview PL926Wbi - recapped, same shut off issue

That's extremely high voltage. The best method is to plug in a spare ccfl and locate the bad bulb.
Your inverter transformers look fine. The readings are within 3% of each other.
Do you have a spare monitor that you can plug in a known good cffl from it into each connector on the bad monitor, and find out which bulb is bad?
retiredcaps also had a way of testing them without a spare ccfl. In his 2 seconds to black guide.

[Wyld_Goose]

Re: Proview PL926Wbi - recapped, same shut off issue

Should I be getting a volt reading from when I test the actual connectors on the inverter that lead to the CCFLs? My DCV only goes up to 1000.

update: never mind I guess it can easily go up and over 1300v

[Wyld_Goose]

Re: Proview PL926Wbi - recapped, same shut off issue

I did a test on the transistors Q5 and Q6 per https://www.badcaps.net/forum/showthread.php?t=7366 thread which deals with the same power board as I have.
Testing pins 1 -3 via 1-2, 1-3, 2-3 to both resister and compare the numbers,then reverse the readings. (My diode tester doesn't give me an option to set it to 2000 or anything else. It simply is what it is)

1-2 on both = 1145 ohms
1-3 on both = 678 ohms
2-3 on both = (climbs up to over 2000 ohms then says "1")

In reverse:

2-1 on both is (climbs up to over 2000 ohms then says "1")
3-1 on both = 1454 ohms
3-2 on both = 296 ohms

[Wyld_Goose]

Re: Proview PL926Wbi - recapped, same shut off issue

I see what my first problem is, when i touch the probes together for an ohms test, my meter reads 002 @2000 ohms. =/

with that said.. S1-S2 I get a reading of 797, S3-S4 I get 805, and both fuses read 002 (which is the same when I touch the probes together.....so should be good?

sigh! faulty equipment.

Got caps in today for my second monitor that did the same thing a few years ago, just decided to hang on to it up in the closet. Wanna guess what my results were after recapping it? GRRR!

I'm not going to post it's pics or meter readings yet, figure at this point, solve one then move on to the next.


**yeah I misunderstood, I originally touched the two pins of S1, then I did the same for S2, and so on. I correctly tested between S1-S2, then S3-S4 this time***

[selldoor]

Re: Proview PL926Wbi - recapped, same shut off issue

Well that sounds bad but I expect you have tested them incorrectly or I have marked the wrong pins!!

Set your meter on 2000 ohms and touch the probes together should read 0.00
or near. Probes apart should read "1" or "OL"

Put red lead on S1 black lead on S2 if there is any lacquer on the joints
scratch through it.
Then Put red lead on S3 and Black lead on S4.


Fuses
Almost the same - POWER OFF Set meter on ohms 200 put one probe on each side of the fuse - should read the same as putting the probes together -0.00

[Wyld_Goose]

Re: Proview PL926Wbi - recapped, same shut off issue

S1-S4 @ meter set to 2000 ohms all read 002

I feel like a bit of a dunce. I'm not sure how to check the fuses. My multimeter doesn't have a continuity function on it. DCV, ACV, DCV, battery tester, OHMs, transistor tester and diode tester is what I got.

[selldoor]

Re: Proview PL926Wbi - recapped, same shut off issue

Also can you retest the 2 fuses F202 and 203

[selldoor]

Re: Proview PL926Wbi - recapped, same shut off issue

Ok Anal we like - saves a lot of problems.

Looks like although it is chipped that Q1 may be ok.

Just before you get to the lamps do this test POWER OFF meter on ohms
2000 test S1 to S2 and S3 to S4 as on attached.
Also if that glue has become hard and is brown you should try and remove it as with age it becomes conductive