Proview PL926Wbi - recapped, same shut off issue

[Wyld_Goose]

I am new to trying to fix a monitor. I have a Proview PL926Wbi that decided to die on me a few weeks ago. I would turn it on and it would turn off but the blue LED light on the power button would stay on. When I would lower the brightness down very low, it would stay on for a while with a little flickering and then turn off. From everything I had read up on, this sounded like a clear case of bad caps. I opened the case and examined the PSU to find no caps that had burst. The caps were a mix of HEC and Procon brands. I could see, what looked like it could be leakage, on the board around 2 of the 220uF caps and when I compared those 2 caps with another 220uF cap in a different location on the board, they clearly were very discolored and dark. I only have a multimeter, so can only check for shorts. Again with everything I had read, better to just go ahead and replace all of the caps. I hadn't discovered digikey at the time and put in an order for all but 4 of the caps from Mouser. (Mouser didn't have the 680uF 25v caps) Not to long after that, I had read up on the big-thumbs-up for Panasonic FM and bought 4 of the 680uF 25v of that model. So this is list of caps that I replaced with:

4x 680uF 25v Panasonic FM
2x 470uF 25v Lelon Low ESR from Mouser
3x 220uF 25v Lelon Low ESR from Mouser
1x 22uF 50v Lelon Low ESR from Mouser
1x 10uF 50v Lelon Low ESR from Mouser

I put the monitor back together and hook her up and she seems to work. After about 10 minutes it start to flicker, so I drop the brightness down and it stabilizes for another 10 minutes and now we are back to shutting off after a few seconds. Aarrgg! I've been doing some reading of threads on the same monitor and it seems that the AS1117 regulator was an issue on some of them. I have to admit, I really don't want to have to remove and replace something that small. With those threads where the regulator was the issue, the monitors didn't come on at all, so I'm not entirely sure if that would be my issue seeings how my monitor does come on. What I'm curious about is with the big 100uF 400v cap that is on the PSU that everyone says not to worry about. On this board it's a HEC brand, on another monitor I'm waiting on parts for, it's the dreaded Fuhjyyu brand.

What are my options at this time? It still seems like it's a cap issue.

[Pentium4]

Re: Proview PL926Wbi - recapped, same shut off issue

You should check to see if the main cap is getting ~165V DC. Also...Lelon aren't a good brand at all, I wouldn't use them even for the less critical caps, you should replace the rest with Panasonic FM/FC. Could you post some clear pictures of the board using the attach function?

[Wyld_Goose]

Re: Proview PL926Wbi - recapped, same shut off issue

I will probably upgrade all of the caps, but for the time being to solve the issue, what I have should be fine. Just not for anything beyond getting this back on it's feet. I will get some pics posted here soon. Leave it to me to have searched for postings but missed the sticky "A guide on how to troubleshoot 2 seconds to black" at the top of this thread. doh!

https://www.badcaps.net/forum/showthread.php?t=10419

Could I get some clarification on something said there?

Since you are seeing the image, but with no backlight, we will assume for now that the power board and logic board are working 100%. That leaves the inverter board to check.

I know of 2 boards in the case, but am unsure of the 3rd. The power board is literally the board that is plugged into from the wall socket, I assume the logic board is the one with the chip(s) on it that sits next, above or under the power board. What is the inverter board?


Actually I see how impossible it is to ask about anything, without pics. I will have them on tomorrow. I was going to ask how I am able to "to see if the main cap is getting ~165V DC" with a multimeter, but that may require pins that you need to see pics of. =/

[retiredcaps]

Re: Proview PL926Wbi - recapped, same shut off issue

What is the inverter board?

Post a clear focused picture of all your boards using the manage attachment function and we can tell you.

[Wyld_Goose]

Re: Proview PL926Wbi - recapped, same shut off issue

The 1st pic is what I believe to be the logic board.
The 2nd pic is a pic of the 200-000-170DTLBMH power board. All caps, except the 100uF 400v, have been replaced.
The 3rd pic is of the reverse side of the power board. Took quite a few pics to get clear identifiers of the points.

OK, so what is the inverter board?

Here are all of the measure voltage readings from all caps, +5, BLON & +14 pins and the HV CCFL outputs:

C11 220uF 25v Measured @ 14.69v
C12 220uF 25v Measured @ 14.69v
*** C22 10uF 50v Measured @ 0.0v !!
C201 100uF 400v Measured @ 159.7v
C206 22uF 50v Measured @ 12.42v
C211 680uF 25v Measured @ 14.69v
C212 680uF 25v Measured @ 5.03v
C213 680uF 25v Measured @ 14.69v
C214 680uF 25v Measured @ 5.03v
C215 470uF 25v Measured @ 14.69v
C216 470uF 25v Measured @ 5.03v
C217 220uF 25v Measured @ 14.69v

CON203 pins=
BLON Measured @ 0.0v
+5 Measured @ 5.03v
+14 Measured @ 14.69v

All 4 High Voltage connectors to the CCFL Measure @ 0.0V

The 4th and 5th pic is of the reverse side of power board zoomed in at a concern with C22 ("C22" can't be seen printed on this side of the board). First of these two pics (4th) is from same angle as the 3rd pic, the 5th pic is of same location, just a different angle. The C22 cap gets a 0 voltage reading. I was concerned originally with the solder as the pics show, when I originally solder wicked away the original solder, what was left behind was the metal exposed on the board as you can see. There is a concern with the resister in the 4th pic just above the "104" resister. I can barely make out a "t04" on it (I'm assuming that it's a resister). The corner closest to the C22 looks chipped.

I haven't looked at the CCFLs yet. I'm trying to find a good video showing someone breaking into the screen. I don't want to start just tearing into it without know what not to touch and such. So far, the best I have found are low resolution videos getting into a laptop screen. (why tear something apart never knowing about that "hidden screw", when you could get a heads-up seeing someone else do it first)

[selldoor]

Re: Proview PL926Wbi - recapped, same shut off issue

It doesnt have an inverter board as such- the inverter transformers are the two big gray
rectangular components in Pic2.
Please can you check all the caps are in the correct way round.
Voltage looks low at the main cap.
Can you go through what happens from switch on to final fault stage what doe the power light do does the screen flash at all any ticking screeching noises.


EDIT
That "resistor" is at Q1 and I think it is a switching transistor - I will try and find it T04 you say?

EDIT2

I think it might be one of these
http://pdf1.alldatasheet.com/datashe...BZX84-A11.html

t= made in malaysia 04

[Wyld_Goose]

Re: Proview PL926Wbi - recapped, same shut off issue

Caps are all in the correct polarity. I was very anal about this seeings how it was my first repair job. Drew up a diagram for myself and everything. But just to check because you asked............. yup totally confirmed.

What happens is exactly what the 2 second to black describes. Click pwr button. blue LED comes on. Screen comes on, then 2-3 seconds later it goes black. No clicks or any sounds. No smells either (I have honestly expected some kind of smell all along) The blue LED stays lit. Hold a flashlight up to it and you can see the screen is on, just not lit up.

I have found a couple threads dealing with this board, and they all seem to end up dealing with the CCFL. Again, I haven't cracked into the actual screen yet to look at the CCFLs. If anyone knows of a good video or step by step, so I can see how to do it right. I don't want to screw something up or touch something or detach something I shouldn't.

**oh and from what I can see on the thing that you think is a switching transistor, what I can see when I look real close is lowercase "t"04 on it. I can't tell if there is or was something after the "4". teenyweeny

[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

[selldoor]

Re: Proview PL926Wbi - recapped, same shut off issue

Also can you retest the 2 fuses F202 and 203

[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

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

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***

[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

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

[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

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

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

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

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 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?