ViewSonic VP201b

[EGuevarae]

Re: ViewSonic VP201b

Exactly!!

PlainBill

[jankro]

Re: ViewSonic VP201b

Hello to everyone, since this is my first post on this forum!

I just received a malfunctioning VP201b and the original owner claimed that the picture rolled from top to bottom.
However, when I unpacked it, it functioned perfectly, hmm...
Since I have been reading a lot about the bad caps in Viewsonics, I decided to take a look inside.
It looked like someone had been there before me, but I removed the power supply to measure the ESR on caps. I found that they were fine, BUT the main 400v cap was totally broken off from is soldering on + side and same thing on one of the legs on a power transistor, other that these probs, it seem to function perfectly.

-Jan

[jankro]

Re: ViewSonic VP201b

It seems that after a few days of working fine, the original fault has returned and it seems to come and go.
Here's some video of it in action:
http://www.youtube.com/watch?v=azFRo8uhad0

After I filmed this, it returned to normal and has been working fine for a couple of hours now.

-Jan

[EGuevarae]

Re: ViewSonic VP201b

It seems that after a few days of working fine, the original fault has returned and it seems to come and go.
Here's some video of it in action:
http://www.youtube.com/watch?v=azFRo8uhad0

After I filmed this, it returned to normal and has been working fine for a couple of hours now.

-Jan

Well. Welcome to the forum
You said you resoldered the 400v cap and power transistors, and that the ESR of the installed caps was OK.
1.- Did you measure the Voltage coming out of the PSU into the main board?
2.- Is there any noise coming from the unit when this happens (I can't hear anything in the video)?

If it is making a sound, it comes from top or bottom of the unit? Or the PSU? It looks like an arcing CCFL. There are 6 CCFLs in there. maybe one degraded and arcs. It is an intermittent failure until it finally dies and the whole backlight subsystems will just shut off.

[jankro]

Re: ViewSonic VP201b

No, I did not measure the voltage and there is really no sound at all.
The picture starts doing that first slowly and the faster and finally it stops, like cut with a knife and picture returns to normal.
I checked all the caps on the power supply, but not the video/control PCB.

Actually, it does not seem to be backlight problem, since the backlight does not flicker at all, it just looks that way, since youtube downgraded the avi file so much.
The backlight stays at constant brightness all the time this is happening.

-Jan

[EGuevarae]

Re: ViewSonic VP201b

No, I did not measure the voltage and there is really no sound at all.
The picture starts doing that first slowly and the faster and finally it stops, like cut with a knife and picture returns to normal.
I checked all the caps on the power supply, but not the video/control PCB.

Actually, it does not seem to be backlight problem, since the backlight does not flicker at all, it just looks that way, since youtube downgraded the avi file so much.
The backlight stays at constant brightness all the time this is happening.

-Jan

Check first if the voltage reading fluctuates (I doubt it because you say the Backlight is constantly on.
Then check the VBoard.

[lucky13]

Re: ViewSonic VP201b

It seems that after a few days of working fine, the original fault has returned and it seems to come and go.
Here's some video of it in action:
http://www.youtube.com/watch?v=azFRo8uhad0

After I filmed this, it returned to normal and has been working fine for a couple of hours now.

-Jan

It is not the p/s.

Look at your main board (where the vga & dvi connects to). If it is covered with browish film. Wash them off. Look on the solder side too.

If that doesn't help, remove the flat cable to the LCD panel, clean it with eraser and insert it back. You can yank off those yellow high temperature tape to access the cable.

[EGuevarae]

Re: ViewSonic VP201b

It is not the p/s.

That's why I said "I doubt it", but I have to rule out that possibility (for the prevous problems he told about), then move on to the VBoard.
The ribbon cable suggestion is great too.I forgot about it.

[burzukk]

Re: ViewSonic VP201b

Thank you guys for all the information here!!! It seems to be a very usefull site for people wanting to repair ther electronics. I am very glad I found this forum!

(please tell me if I'd better start a new post, but I think i'm on the right topic)

Here's my situation:

I have a vp201b
It stopped working yesterday, green led stays on, but no image.

During the last year it went though intense pink flickering issues that I gently solved by hitting the screen on its bottom. I thought that backlamps could have been slightly out of socket (are theses soldered?). Recently, it worked pretty well, without any flickering issues at all... then just shut the image off yesterday, without any other sympthoms.

I did unsrcrew the whole thing, then visually inspected all the caps (Rubycon). Nothing catched my eye. Then I tested the current out of the red and black wires of the power supply: 17,83v (I assume it's ok).

I looked at the 2 fuses on the inverter panel, theses seem visually ok to me, i tested if current goes through: it does.

My assumption is that the backlights are blown. When I took the whole thing appart, I thought I saw some brownish crap on two of the tubes, but now It somehow disapered... Can they blow altogether? Can any other part could have make theses blow? (appart from me hitting it.. i know) Is there any way to make sure theses are blown, any other things to look for before trying to replage theses?

and a last thing... i've looked everywhere for the lights... anybody knows where to find this part, or at least the part number...

Thanks a lot guys!!

[PlainBill]

Re: ViewSonic VP201b

Thank you guys for all the information here!!! It seems to be a very usefull site for people wanting to repair ther electronics. I am very glad I found this forum!

(please tell me if I'd better start a new post, but I think i'm on the right topic)

Here's my situation:

I have a vp201b
It stopped working yesterday, green led stays on, but no image.

During the last year it went though intense pink flickering issues that I gently solved by hitting the screen on its bottom. I thought that backlamps could have been slightly out of socket (are theses soldered?). Recently, it worked pretty well, without any flickering issues at all... then just shut the image off yesterday, without any other sympthoms.

I did unsrcrew the whole thing, then visually inspected all the caps (Rubycon). Nothing catched my eye. Then I tested the current out of the red and black wires of the power supply: 17,83v (I assume it's ok).

I looked at the 2 fuses on the inverter panel, theses seem visually ok to me, i tested if current goes through: it does.

My assumption is that the backlights are blown. When I took the whole thing appart, I thought I saw some brownish crap on two of the tubes, but now It somehow disapered... Can they blow altogether? Can any other part could have make theses blow? (appart from me hitting it.. i know) Is there any way to make sure theses are blown, any other things to look for before trying to replage theses?

and a last thing... i've looked everywhere for the lights... anybody knows where to find this part, or at least the part number...

Thanks a lot guys!!

The pink flickering would indicate failing CCFLs. There are several tests to try.

1. What happens if you turn the monitor off, then on by pressing the power button on the front of the monitor?

2. When you have the green power LED AND are sending a good signal to the monitor can you see an image when you use a bright light to illuminate the screen?

The best way to test the CCFLs and the inverter is by buying a 'cold cathode light kit' used for 'modding' computer cases (available for under $10 on eBay). Use the inverter in the kit to power the CCFLs in the monitor; use the CCFLs in the kit to test the inverter in the monitor.

CCFL lamps come in a wide variety of diameters and lengths. Google CCFL Lamp or CCFL Backlight to find suppliers.

PlainBill

[burzukk]

Re: ViewSonic VP201b

Awesome, thanks for the fast reply!

I'll reassemble the monitor and do the flashlight test and get back to you!!

[EGuevarae]

Re: ViewSonic VP201b

The pink flickering would indicate failing CCFLs. There are several tests to try.

1. What happens if you turn the monitor off, then on by pressing the power button on the front of the monitor?

2. When you have the green power LED AND are sending a good signal to the monitor can you see an image when you use a bright light to illuminate the screen?

The best way to test the CCFLs and the inverter is by buying a 'cold cathode light kit' used for 'modding' computer cases (available for under $10 on eBay). Use the inverter in the kit to power the CCFLs in the monitor; use the CCFLs in the kit to test the inverter in the monitor.

CCFL lamps come in a wide variety of diameters and lengths. Google CCFL Lamp or CCFL Backlight to find suppliers.

PlainBill

I agree with PlainBill. Pink hue= dead (or about to die) CCFLs.
Also agree on the case light kit method, as that's what I use.

[burzukk]

Re: ViewSonic VP201b

Ok, I did reassemble the monitor, I see the faint image with the spotlight. I also spotted back the brownish things near the bachlights... It's actually the thick transparent plastic that seems to have to small melting spots near the begenning of the backlights, on the left... Same thing for the upper lights.

It seems to have overheated over time (I use this monitor A LOT)

I'll look for ccfl, dependind on the cost, I might just try my luck at buying theses directly without testing with the case modding kit, even if this semms to be the best method.. I need this monitor asap, and since the flickering issue, changing lights could not be a bad thing.

Thanks again for your help guys, i'll get back with results!

[burzukk]

Re: ViewSonic VP201b

Ok,

I spotted this place..

http://www.lcdparts.net/ccfldetail.a...ctCCFL=MS26413

they sell theses 13$ each.
from what I saw in the monitor, I need 6 fo theses.
they also want to sell me silicon caps... do I need this?

Do you believe this is what it's supposed to be worth?

Thx again!

[PlainBill]

Re: ViewSonic VP201b

Ok,

I spotted this place..

http://www.lcdparts.net/ccfldetail.a...ctCCFL=MS26413

they sell theses 13$ each.
from what I saw in the monitor, I need 6 fo theses.
they also want to sell me silicon caps... do I need this?

Do you believe this is what it's supposed to be worth?

Thx again!

Also look here: http://www.ccflsurplus.com/26x41fuspcc.html

PlainBill

[burzukk]

Re: ViewSonic VP201b

nice... cheaper

you think I need the caps and rings?

http://www.ccflsurplus.com/2siendca.html
http://www.ccflsurplus.com/siliconorings.html

[PlainBill]

Re: ViewSonic VP201b

nice... cheaper

you think I need the caps and rings?

http://www.ccflsurplus.com/2siendca.html
http://www.ccflsurplus.com/siliconorings.html

I don't know. It would depend on the condition of the originals and the care you took in removing them.

PlainBill

[fritz]

Re: ViewSonic VP201b

Great forum.
I was given a vp201b - I have determined the main power supply is bad. Puts out 18VDC disconnected but drops to 4VDC when connected. I wired up a 16.9VDC brick PSU to the main board and the monitor works beautifully.

I still want to fix the main power supply.
Two Ltec 680uF 25V with bulging butts are the main suspects.
They measure 200 and 460 uF respectively.
A Taicon 150uF 400V cap measures 130uF - tolerable?

So far so good: should I expect anything beyond that?
Thanks in advance

[PlainBill]

Re: ViewSonic VP201b

Great forum.
I was given a vp201b - I have determined the main power supply is bad. Puts out 18VDC disconnected but drops to 4VDC when connected. I wired up a 16.9VDC brick PSU to the main board and the monitor works beautifully.

I still want to fix the main power supply.
Two Ltec 680uF 25V with bulging butts are the main suspects.
They measure 200 and 460 uF respectively.
A Taicon 150uF 400V cap measures 130uF - tolerable?

So far so good: should I expect anything beyond that?
Thanks in advance

Nope, just replace the two Ltec caps. The Taicon is seldom a problem.

PlainBill

[EGuevarae]

Re: ViewSonic VP201b

Nope, just replace the two Ltec caps. The Taicon is seldom a problem.

PlainBill

I agree. I have repaired three VP201 and two VP211 (it's 21.1" cousin) besides one unit I have that needs a panel. Always the 680uf ones on the PSU.
Leave the big fat bad boy alone. I don't think it is the trouble.