ViewSonic VX922 and VX724 Bad CapXon

[Hunt]

Re: ViewSonic VX922 and VX724 Bad CapXon

That looks like the correct schematic. That is what you have, that IC is the same P/N as in the link I provided.
When that IC blew up like that, it may have taken out ZD120, ZD121 with it too, so check RESISTANCE of those two diodes to make sure they do not show low resistance (100 Ohms or less).

I have just been checking those diodes (Diodes removed from board) and I am confused by the 100 ohms or less.
Using a meter that has a diode option. The open circuit setting (probes not touching) is 1466 mV (dropping with use)...
Both diodes connected to the meter the correct way round negative probe to silver band 462mV-482 mV
Both diodes connected the wrong way round positive probe to the silver band 1466-1460 mV open circuit.

With the ohms meter setting...
The wrong way positive to the silver band open circuit.
the correct way negative to the silver band 4.8 to 6.4m Ohms.

[Hunt]

Re: ViewSonic VX922 and VX724 Bad CapXon

That looks like the correct schematic. That is what you have, that IC is the same P/N as in the link I provided.
When that IC blew up like that, it may have taken out ZD120, ZD121 with it too, so check RESISTANCE of those two diodes to make sure they do not show low resistance (100 Ohms or less).

Thanks guys, I will now start to look for parts.

[budm]

Re: ViewSonic VX922 and VX724 Bad CapXon

That looks like the correct schematic. That is what you have, that IC is the same P/N as in the link I provided.
When that IC blew up like that, it may have taken out ZD120, ZD121 with it too, so check RESISTANCE of those two diodes to make sure they do not show low resistance (100 Ohms or less).

[will62]

Re: ViewSonic VX922 and VX724 Bad CapXon

Does the attached schematic match your board?

[budm]

Re: ViewSonic VX922 and VX724 Bad CapXon

That circuit is for the main board, not for the power supply board.

[Hunt]

Re: ViewSonic VX922 and VX724 Bad CapXon

I've stumbled on this; however I cannot see U101...

[Hunt]

Re: VierwSonic VX922 and VX724 Bad CapXon

Your board is FSP043-2P101?
There are more than one version of the power supply used in that VX922 as you can see in my photo bucket.
One board uses IC but another board version uses 3-pin MOSFET.
Does that U101 have 3 pins or 6 pins?
I think your board uses POWER SMPS IC.
https://cdn.badcaps-static.com/pdfs/...5a94e9d98e.pdf

I think RB is being used on your board, not 100% sure though since I did not look real close at the spec to see what the difference between RE and RB is.
https://cdn.badcaps-static.com/pdfs/...c1a6d1361f.pdf

I see what you mean; yes, the U101 does indeed have 6 pins.
The board has FSP043-2PI01 printed on it.
P/N: 3BS010131 3GP Rev:1

[Per Hansson]

Re: VierwSonic VX922 and VX724 Bad CapXon

2. 400v 100uf electrolytic positive wire has what looks like burnt electrolyte oozing out, C114.

Probably this caused the failure.
Try desoldering it: probably the lead has corroded off meaning the poor regulator had to run without any bulk capacitor as best it could!

[budm]

Re: VierwSonic VX922 and VX724 Bad CapXon

Your board is FSP043-2P101?
There are more than one version of the power supply used in that VX922 as you can see in my photo bucket.
One board uses IC but another board version uses 3-pin MOSFET.
Does that U101 have 3 pins or 6 pins?
I think your board uses POWER SMPS IC.
https://cdn.badcaps-static.com/pdfs/...5a94e9d98e.pdf

I think RB is being used on your board, not 100% sure though since I did not look real close at the spec to see what the difference between RE and RB is.
https://cdn.badcaps-static.com/pdfs/...c1a6d1361f.pdf

[Hunt]

Re: VierwSonic VX922 and VX724 Bad CapXon

U101 is the SMPS IC, not rectifier.
Can I see the pictures of the whole board?

Stunningly fast response!

Here it is.
Do you think I have a chance of repairing this if I change those components?

P.S.
From looking at DSC00276.jpg of yours, the SMPS IC is a CET ? ,5, 4?, 2, M/ , Z last line C?, E , F, ? 4 N G

[budm]

Re: VierwSonic VX922 and VX724 Bad CapXon

U101 is the SMPS IC, not rectifier.
Can I see the pictures of the whole board?

[Hunt]

Re: VierwSonic VX922 and VX724 Bad CapXon

Well what ever it was it never came back!

Thanks to this site it is still working as I type this comment

9 years on and those caps that were bad and repaired are still going strong

Unfortunately the power supply has gone with a bang.
1. The single (rectifier) on the heat sink that is at right angles to the heat sink that usually has the bad caps has burnt out, U101.
Anyone know the part number for this?
2. 400v 100uf electrolytic positive wire has what looks like burnt electrolyte oozing out, C114.
3. Not related, I think to the current problem; however, seem sensible to replace 470uf 10v electrolytic that is swelling at the top, c242.

[lordgalla]

Re: VierwSonic VX922 and VX724 Bad CapXon

Can you post pictures of your repaired board(s)? Also, what brand of capacitors did you use for the recap and where did you buy them from?

Hello,Here is the photo of my board I replaced the caps on,I bought them from ebay,and I think they are CapXon brand.The monitor is working fine except for this contrast popping up and lowering it to minimum on it's own.

[momaka]

Re: VierwSonic VX922 and VX724 Bad CapXon

Hi guy's,I have done the repair on a Viewsonic VX922.Worked great for months,now all of a sudden the OSD contrast pops up on screen and lowers the contrast all by itself,and I can't stop it.

Can you post pictures of your repaired board(s)? Also, what brand of capacitors did you use for the recap and where did you buy them from?

[lordgalla]

Re: VierwSonic VX922 and VX724 Bad CapXon

Hi guy's,I have done the repair on a Viewsonic VX922.Worked great for months,now all of a sudden the OSD contrast pops up on screen and lowers the contrast all by itself,and I can't stop it.If I shut down the monitor,hold power button for 30 sec. and then start up the monitor,it works ok with no problems for about 5min. or so and then the contrast pops up again,and lowers contrast,and I can't stop it,I can raise the contrast and as soon as I let go of the button,it lowers it all the way down all by itself?? any help much appreciated.Thankyou.

[Hunt]

Re: VierwSonic VX922 and VX724 Bad CapXon

Thanks for the information guys/gals
Worked perfectly the first time I fired the PC up!
One slight niggle is when I fired the PC up the next day the screen was like a water colour paining were the paint had run
After leaving it on for an while it reverted back the a great picture.
Subsiquent cold starts have been ok.

Any ideas all; as to what the problem could be?

Well what ever it was it never came back!

Thanks to this site it is still working as I type this comment

[jsaily]

Re: VierwSonic VX922 and VX724 Bad CapXon

I repaired yesterday a VX724 which was salvaged from the company dumpster.

I have to say that at first the inverter board look beyond repair since the large 100uF / 400V cap had leaked badly and the board was also pretty red due to overheating. All other caps were also bulging. I immediately suspected that the switcher IC (SG6841S) could be damaged because of the primary side cap failure... Strangely enough not even the fuse was blown and all semiconductors tested ok. Replacing all small caps with new low ESR ones and using a transplant 100uF/400V cap from a donor board revived the monitor! The picture is clear and sharp as ever. It's a perfect Christmas gift to my father-in-law!

[nuryev]

Re: VierwSonic VX922 and VX724 Bad CapXon

Just completed a successful repair to Viewsonic VX922 - thanks to the detailed instructions and advice provided by people on this site. Another piece of electronic equipment not going to the junk pile - you are all doing your bit to save our planet.

YOU GUYS ROCK!!!!!

Pity we can't desolder and replace some caps to change people's attitudes to waste and pollution.

Thanks everyone for sharing your problems and posting pics of the powersupply boards and caps.

[Hunt]

Re: VierwSonic VX922 and VX724 Bad CapXon

Thanks for the information guys/gals
Worked perfectly the first time I fired the PC up!
One slight niggle is when I fired the PC up the next day the screen was like a water colour paining were the paint had run
After leaving it on for an while it reverted back the a great picture.
Subsiquent cold starts have been ok.

Any ideas all; as to what the problem could be?

[kc8adu]

Re: VierwSonic VX922 and VX724 Bad CapXon

it does not matter.not a timing element.
larger,lower esr =longer life.