ViewSonic VP201b

[PolishPaul]

Re: ViewSonic VP201b

lol.. dOmed... I don't believe they were... And no offense taken whatsoever

[pixelvisions]

Re: ViewSonic VP201b

Good evening gents... my USB ports aren't supplying power. I suspect a fuse is out for the hub. My computer is recognizing the monitor when I plug it in... but it is not sending juice to the 4 USB ports. Is this fuse easily replaceable... I searched through the images in this thread and it didn't stand out.

Also, I found a service manual online for anyone that is interested:

[PlainBill]

Re: ViewSonic VP201b

Good evening gents... my USB ports aren't supplying power. I suspect a fuse is out for the hub. My computer is recognizing the monitor when I plug it in... but it is not sending juice to the 4 USB ports. Is this fuse easily replaceable... I searched through the images in this thread and it didn't stand out.

Also, I found a service manual online for anyone that is interested:

Check IC955; that appears to be the voltage regulator for the USB section.

PlainBill

[lucky13]

Re: ViewSonic VP201b

Good evening gents... my USB ports aren't supplying power. I suspect a fuse is out for the hub. My computer is recognizing the monitor when I plug it in... but it is not sending juice to the 4 USB ports. Is this fuse easily replaceable... I searched through the images in this thread and it didn't stand out.

Also, I found a service manual online for anyone that is interested:

Nice find. Thanks for sharing. This one does have schematics for the p/s too!

You should check that 6-wire connector to see if your 5v is there to the USB board or not.

[jankro]

Re: ViewSonic VP201b

If you back up a little bit on that FTP address, there are many other service manuals for other Viewsonics too:
http://ftpkuban.com/FTP/Manual/ViewSonic/

-Jan

[jankro]

Re: ViewSonic VP201b

I got another VP201b to play around with. It had some problems when picture was very bright it starts to flicker.

I checked the power and inverter caps, they were file, then I started to check the main board SMD caps and some were 2-10 times the ESR what they are supposed to be.
Has anyone replaced these main board caps?

-Jan

[alexanna]

Re: ViewSonic VP201b

I am probably showing my ignorance here, but is it possible to get an accurate reading of one smd cap still on the board?
Al.

[jankro]

Re: ViewSonic VP201b

That is a very good question. I was wondering that too. I know that "normal" electrolytics can be measured reliably while in ircuit, but I'm not sure about SMD's.

Well the second VP201b had a bad inverter (fuses and caps fine). Backlight flashed briefly at startup so I replaced the inverter and it seems to be fine now. Ihad a spare inverter from my first VP201 from which I borrowed the panel to fix a vertical striped Dell 2001FP (the vertical stripe is caused by defective panel).

-Jan

[el3ctroded]

Re: ViewSonic VP201b

Initial things to check on that bad inverter board are the transistors or the transformers...

[nickmaynard]

Re: ViewSonic VP201b

Just wanted to thank you all on this thread for your assistance diagnosing & fixing my problem.

My display cut out suddenly one evening - green LED, but no display. If I was lucky, on power on I'd get a slight flicker in the display.

I followed the service manual instructions for this, leading to an inverter failure diagnosis.

Testing inverter fuses, I found one had blown, which I replaced with a glass fuse and holder from Maplin (UK electronics store):
10x 20mm 2A Quick Blow glass fuses: GG26D
1x PCB fuse holder with cover: KU29G

Attached photo is of new fuse holder & fuse. At this point, I had progress; I'd get a display for about 1s on power on, then the display would cut out as before.

Though they looked absolutely fine, I replaced both 220uF capacitors on the inverter board, again with kit from Maplin:
2x 220uF 35V 105C radial capacitors: N86KF

The solder holding the old caps onto the board wouldn't melt with my 40W iron, so I clipped off the old caps and joined the new cap leads onto the old cap leads (and thus the PCB). No photos of this I'm afraid.

This fixed it - happy days.

All in all, about £5 to fix a £600 monitor. Thanks again.

Service manuals:
Revision 1b: http://dl.dropbox.com/u/845142/Manua...b_%5BET%5D.pdf
Revision 1d: http://dl.dropbox.com/u/845142/Manua...1b-1_SM_1d.pdf

[Thornapple]

Re: ViewSonic VP201b

*** Second attempt ***

Four years since I visited this thread. I'm glad it's still here because I still have the VP201b but it has developed a problem. It flickers for 10 minutes before the lighting becomes even and even then it is prone to start flickering again at intervals.

I've taken some pictures of the innards and based on what I have read in this thread I have a notion what the problem is, but would like confirmation.

First, the inverter board:



The pic doesn't show the cap ends but they are flat [the monstrosity on red wires is a DIY fuse].

The centre board:



I can't see anything wrong there.

Finally, the power board:



Of the six caps visible four have flat ends, but the two at the top right (680uF 25V) appear to be bulging:



Closer up:





I would grateful if someone would cast an eye on those pics, especially the last two, and say what they think.

[Thornapple]

Re: ViewSonic VP201b

*** images not working on previous post....retrying......***

[lexwalker]

Re: ViewSonic VP201b

Four years since I visited this thread. I'm glad it's still here because I still have the VP201b but it has developed a problem. It flickers for 10 minutes before the lighting becomes even and even then it is prone to start flickering again at intervals.

I've taken some pictures of the innards and based on what I have read in this thread I have a notion what the problem is, but would like confirmation.

First, the inverter board:



The pic doesn't show the cap ends but they are flat [the monstrosity on red wires is a DIY fuse].

The centre board:



I can't see anything wrong there.

Nice. They used Rubycons YXG capacitors, albeit the lower range for low ESR type. Kinda extremely rare to see quality capacitors on LCD monitors nowadays...

Finally, the power board:



Of the six caps visible four have flat ends, but the two at the top right (680uF 25V) appear to be bulging:



Closer up:





I would grateful if someone would cast an eye on those pics, especially the last two, and say what they think.

Those bulging and leaking Ltec capacitors has to be replaced. Looking at the proximity of the heatsinks, its not surprising to see those capacitors go bad easily. Try replacing them first.

[Thornapple]

Re: ViewSonic VP201b

Thanks for the confirmation Lexwalker.

My next question is...how do I remove that board to change those two capacitors? I can see six disconnections that must be made, shown by the two yellow arrows:



The white plug is no problem. The five connections to the mains input socket are hopefully spade connectors and will come out with persuasion. But I can see a problem with the inflexible metal lugs (green arrows) holding the board down, and much worse, the curious tag thing marked by the red arrow. When I undo that screw I can't see any way I will be able to lift the board without cutting a slot in it to let the tag through. I can't even pivot the board upright (lifting the left hand side) because the mains socket will knock against the metal lugs immediately above and keep it down.

[Wrog]

Re: ViewSonic VP201b

My next question is...how do I remove that board to change those two capacitors? I can see six disconnections that must be made, shown by the two yellow arrows:

The white plug is no problem. The five connections to the mains input socket are hopefully spade connectors and will come out with persuasion. But I can see a problem with the inflexible metal lugs (green arrows) holding the board down, and much worse, the curious tag thing marked by the red arrow. When I undo that screw I can't see any way I will be able to lift the board without cutting a slot in it to let the tag through. I can't even pivot the board upright (lifting the left hand side) because the mains socket will knock against the metal lugs immediately above and keep it down.

Remove red arrow screw. Disconnect far left arrow connector. Slide PCB to the right so that the rectangular holes are positioned beneath the metal lugs. Lift board out.

[Thornapple]

Re: ViewSonic VP201b

Remove red arrow screw. Disconnect far left arrow connector. Slide PCB to the right so that the rectangular holes are positioned beneath the metal lugs. Lift board out.

Just need my caps now

[lexwalker]

Re: ViewSonic VP201b

Just need my caps now

Do check the capacitor size when ordering, note the dimensions of the original capacitors (diameter x height x lead pitch). I used Panasonic FMs a lot (till ran out of stock in hand recently) but quite often due to space constraints on the board (since Panasonic FMs are much bigger) I revert to using Panasonic FR, Panasonic FK and Nichicon PS due to their smaller size.

Recommended capacitors...

- Panasonic FM, FR, FK, FC series
- Nichicon HE, PW, PS series
- Rubycon ZL, YX series

Those in bold are the ones I've used most often. Rarely used Rubycon though...

[Thornapple]

Re: ViewSonic VP201b

Do check the capacitor size when ordering, note the dimensions of the original capacitors (diameter x height x lead pitch). I used Panasonic FMs a lot (till ran out of stock in hand recently) but quite often due to space constraints on the board (since Panasonic FMs are much bigger) I revert to using Panasonic FR, Panasonic FK and Nichicon PS due to their smaller size.

Recommended capacitors...

- Panasonic FM, FR, FK, FC series
- Nichicon HE, PW, PS series
- Rubycon ZL, YX series

Those in bold are the ones I've used most often. Rarely used Rubycon though...

Oops...spotted this just after sending the order. The place I've ordered from doesn't give dimensions, make or any picture. The only info is the temperature rating (105C). I'll have to wait and see what turns up. If they're no good I'll look elsewhere...not that we have much choice in UK.

[Thornapple]

Re: ViewSonic VP201b

Reporting back

The replacement caps may have been unbranded...



...and the soldering job may have lacked finesse....



...but it worked!



Thanks everyone

[retiredcaps]

Re: ViewSonic VP201b

The replacement caps may have been unbranded...

Those are Panasonic FR. Panasonic changed the sleeve and design compared to the FM/FC series.