Viewsonic VX2235WM White Display

[sghill99]

I've looked around and gotten some feedback from members here. They suggested looking for a fuse on what I imagine is the inverter (but I'm probably wrong about the board being the inverter).

I think I may have located the problem. I've attached a few pics of "F1." I've checked for continuity, and the DMM doesn't beep, so I'm assuming this fuse isn't working.

I can't identify what this is, or where I would buy one.

I've got access to the service manual, but am not sure if I'm allowed to post it here in the forum, so I wont for now.

Thanks for any help!

[sofTest]

Re: Viewsonic VX2235WM White Display

This looks like it's the logic/video board. It's a SMD (surface mount) fuse. You should be able to get it at DigiKey.com. Just measure the physical size, and look up the value in the service manual. It would be nice if you post the value here, in case someone else need it.

[sghill99]

Re: Viewsonic VX2235WM White Display

I wasn't sure if it was okay to post the service manual. If the moderator doesn't mind I will. Please let me know, and I'll post it today.

I looked in the manual, and can't find the value for this fuse. As a novice, I'm probably not looking in the right place.

[sam67]

Re: Viewsonic VX2235WM White Display

The fuse can cause a white display..now once you find the right fuse you need to find out why it blow ...could be just at the end of it's life span or something else caused it to go..I would order a couple just incase the new one goes..I know you can remove the fuse and put a 100w light bulb across the fuse holder to check if there is a short anywhere else but not sure with this as i once used this method on a psu that would blow fuses everytime i changed them. It worked for me but this might not for you.Someone with more ITK will put you straight ..So don't try owt just yet lol... But do keep in mind why has the fuse blown.

[sghill99]

Re: Viewsonic VX2235WM White Display

I wasn't sure about attaching the links for these until I checked with the moderator to make sure it was okay.

Anyway, here they are. The reason there are three is as follows, the monitor I have is a Viewsonic VX2235WM. When I opened it up and looked at the power supply board the label on it was VG2030WM. So to cover all the bases, I got both. Well it turned out that three arrived.

Anyway, if anybody out there who knows how to read these things is able to
identify Fuse "F1" I'd really appreciate it. I realize that there is possibly an underlying reason why it blew, so if you might ponder that issue as well, I'd also appreciate that!

I hope these service manuals help other members who are experiencing similar
problems with their LCD!

When I tried to upload these to the Badcaps server, they wouldn't upload
because they were too big, so I put them on my idisk... Hope you are able
to look/get them! They will be there for 30 days.

Viewsonic VG2030WM-1 http://files.me.com/scottghill/300x8w
Viewsonic VX2235WM-1 http://files.me.com/scottghill/fdwrq2
Viewsonic VX2235WM-9 http://files.me.com/scottghill/euirqa

Thanks again!!!

[seanc]

Re: Viewsonic VX2235WM White Display

That board is off of the LCD panel, isn't it.

What panel is it, Chei Mei? You probably need to see if you can find a schematic for that board or the LCD panel.

[kc8adu]

Re: Viewsonic VX2235WM White Display

iirc the one i had was a 3a.
it was white and would slowly turn both dark and colored lines.the fuse fixed it.

[sghill99]

Re: Viewsonic VX2235WM White Display

kc8adu THANKS! You had the same problem with the same monitor and it fixed it? Great! There wasn't anything else causing the fuse to blow? You say 3A, is there a voltage I need to get? Any suggestions where to get it?

In the real big pic of the fuse it looks like the soldier joint on one side looks a little strange.

[sghill99]

Re: Viewsonic VX2235WM White Display

I think this is the actual service manual for the monitor I have. I looked it over and one of the circuit boards is labeled VG2030WM. So I'm certain this is the correct service manual for a VX2235WM-3. I looked at this one too and don't see that "F1" fuse.

Help!

http://files.me.com/scottghill/h86up2

[sghill99]

Re: Viewsonic VX2235WM White Display

I think I figured out why the schematic for this part of the monitor is not in the service manual. The LCD screen and associated circuit board are apart form the monitor service service manual. The LCD screen has it's own service manual.

The service manual for a M220EW01 22" LCD screen is included in this post (I think). It looks like "F1" is 5V, not sure about the amps, unless kc8adu is correct at 3A.

http://files.me.com/scottghill/noyvbb

Any thoughts?

[sofTest]

Re: Viewsonic VX2235WM White Display

If your last link is the service manual for the board, it says on page 13:
- 5v (+/- 10%)
- max. 1272 mA (1.272 A) input current

So, I'm thinking a 24V 1.5A SMD fuse (DigiKey part P11365CT-ND) might be appropriate. Can anybody else confirm?

[MDOC]

Re: Viewsonic VX2235WM White Display

If your last link is the service manual for the board, it says on page 13:
- 5v (+/- 10%)
- max. 1272 mA (1.272 A) input current

So, I'm thinking a 24V 1.5A SMD fuse (DigiKey part P11365CT-ND) might be appropriate. Can anybody else confirm?

Yes, I can confirm, but note that the inrush current spec is TBD. We don't know what this current is, so for this reason I suggest going to 2A.
After all, this is a fast-acting fuse and it'll blow before any damage occurs.

[sghill99]

Re: Viewsonic VX2235WM White Display

Thanks much I'll get both, just in case...

[sghill99]

Re: Viewsonic VX2235WM White Display

I got the fuses today.

They are 0402 SMD. It looks like I should have gotten 0603 SMD. It looks like the 0402 will fit in okay, I should be able to soldier in the component, it's just a little smaller.

Do you think I will run into any problems using the 0402 instead of the 0603? The only difference between the specs are the 0402 are 24V and the 0603 are 32V. Both are 2A.

From what I've learned from other Badcaps members, the voltage going through the fuse will be less that 24V.

Thanks in advance, I'd like to get one of these soldiered in, THEY ARE SMALL!

Scott

[sofTest]

Re: Viewsonic VX2235WM White Display

Voltage on fuses are up-to values. The spec in your manual said this was a 5v line, so as long you are able to solder it in, it should work.

[sghill99]

Re: Viewsonic VX2235WM White Display

I just got the 0603 out, THAT WAS SMALL! I've got a pretty steady hand, but I'm not sure I can get the 0402 in. It's about half the size of the 0603. I'm tempted to order the 0603 and wait, but it's killing me to get this fuse in!

When I tried to use my forceps to pick-up the fuse, it must have shot out of the forceps! Can't even find it!

Guess the worst that could happen is that I couldn't get it soldiered in and I'd have to order the 0603!

Thanks!

[sghill99]

Re: Viewsonic VX2235WM White Display

Well, I got the fuse in (had continuity) put everything back together and it blew again (no continuity).

There are two voltage regulators right next to the fuse, a 3.3V and a 1.8V. Do you think one or both may be causing the short? How would I measure these? Is there anyway to test these out of circuit?

When I start the monitor, it's black for a second, then goes to white. When hooked up to a PC, the PC recognizes that the monitor is there. When hooked up to a PC the power light remains blue.

Any suggestions as to where I should go from here?

Thanks much, I don't want to give up!!!

[sofTest]

Re: Viewsonic VX2235WM White Display

It's difficult to say what's causing the fuse to blow. I had a new look at your board, and it seem like there might have been some heat on the components (C22, D3) in the upper right corner, as seen on the first picture. I usually probe around, test the diodes, resistors and so on for values and shorts, without power. If I find unexpected results, I remove the component and test them again. If that doesn't give any result, the trick of replacing the fuse with a light bulb, and measure the voltages might be the next step.

[MDOC]

Re: Viewsonic VX2235WM White Display

Any suggestions as to where I should go from here?

Thanks much, I don't want to give up!!!

Huh, a fuse blowing means you have a short somewhere. I should have checked that first, sorry about that.

It's the fuse circled in the pix below, right? If so, measure resistance across C1 cap (with everything connected together). How near to zero is it?

(Another way is to measure between Vcc and GND on each board, looking for a short or a relative short.) The board with the nearest short is probably the one you should look closely at.

[sghill99]

Re: Viewsonic VX2235WM White Display

In examining the schematic re: this IC board that's attached to the top of the LCD screen it looks like there is alot more stuff on the board than is pictured in the schematic. Without a good schematic, isn't it kind of difficult to figure out what might be wrong with the board?

With that in mind, since I feel that it's me against the monitor, I'm thinking about buying another broken monitor, same model, on eBay, that appears to have something different wrong with it. That way, I can get my hands on a good board and use it to make measurements. Is this crazy?

I don't see any other way around it, not having a good schematic.

Any thoughts?