Viewsonic VX1962wm, I think it just needs caps, need confirmation

[aerostarlegacy]

Hi, I have a vx1962wm.
It turns on for a few seconds, then goes black; the power light stays blue. I can turn it off and then back on, and the picture will reappear for a few seconds again, then go black again.
There is a high pitched electrical sound from it when it is on and the picture is showing, the sound dies when the picture dies.
I have read some threads here and it seems that I am another victim of CapXon. Two of the caps seem to be bad, the other 4 look good, including the big filter cap.

However, there is also a dark area on the board with a part behind it. I don't know what it is. The model is:
"NIKOS
P2804ND5G
UN45J0D9B"
it sorta looks like it could be burned out, but I can't tell for sure.

Obviously I should replace the busted caps with better ones.

But my question to you is: should I replace ALL the caps, and should I replace the little doohickey on the back of the board (the NIKOS thingie)?

Thanks!

[jetadm123]

Re: Viewsonic VX1962wm, I think it just needs caps, need confirmation

Yes, two caps are definitely bad. However, with the exception of the large 400V cap, all five of the smaller ones should be replaced. Use Panasonic FM or FC caps available from digikey.com. Replace caps first, before anything else.

The dark spot you see is generated by the Nikos p2804 mosfet. Since it is soldered directly to the circuit board and generates a lot of heat, it will discolor the board over time.

[aerostarlegacy]

Re: Viewsonic VX1962wm, I think it just needs caps, need confirmation

So, do you think that mosfet is working properly? Is it supposed to discolor the board?

Also, there are many types of caps for sale on digikey, which kind do I get? I'm assuming aluminum, but I'm not sure.

[momaka]

Re: Viewsonic VX1962wm, I think it just needs caps, need confirmation

So, do you think that mosfet is working properly?

You can see the screen for a few seconds when you turn it on, so yes, it should be working fine.

Is it supposed to discolor the board?

No.
But I think that's just bad design on Viewsonic's part or whoever manufactured the power supply. There just needs to be more cooling in that area. The ripple from the bad CapXon caps probably also contributed to the problem.

Also, there are many types of caps for sale on digikey, which kind do I get? I'm assuming aluminum, but I'm not sure.

Yes, aluminum electrolytic.
Which series of CapXon caps do you have? I can see the black one next to the video/logic board connector is KM series.
CapXon KM can be replaced with United Chemicon KY and Nichicon HE series. United Chemicon KZE, Rubycon ZL, and Panasonic FR and FM should also work fine.

[aerostarlegacy]

Re: Viewsonic VX1962wm, I think it just needs caps, need confirmation

The green ones are GF series and the black ones are KF series. I notice 2 different types of caps on digikey that seem to fit the specs of these: ones that look very similar to these, and shorter, fatter silvery ones. are those better/worse/different at all?

Also, what's a good way to disengage the caps from the white glue/cement stuff that seems to be everywhere?

You mention six different models that should work well, does it matter which ones I get, or are they all good?

Are the only specs I need to worry about the voltage and capacity? or do I need to match up the ohms and ripple and variance and color and whatnot?

[PlainBill]

Re: Viewsonic VX1962wm, I think it just needs caps, need confirmation

The green ones are GF series and the black ones are KF series. I notice 2 different types of caps on digikey that seem to fit the specs of these: ones that look very similar to these, and shorter, fatter silvery ones. are those better/worse/different at all?

Also, what's a good way to disengage the caps from the white glue/cement stuff that seems to be everywhere?

You mention six different models that should work well, does it matter which ones I get, or are they all good?

Are the only specs I need to worry about the voltage and capacity? or do I need to match up the ohms and ripple and variance and color and whatnot?

The glue can usually be pried off with a fingernail. Just give it time to yield.

I prefer Panasonic FM FR, and FC. The other brands / series are also good.

I wrote this procedure for selecting caps. Of course, you can substitute other series simply by changing 'FM' to whatever series you are interested in.

Primary requirements are capacitance and voltage. Height and diameter are also important, so check the dimensions of the proposed replacement. It's REALLY embarrassing when you can't get the back on.

PlainBill

[momaka]

Re: Viewsonic VX1962wm, I think it just needs caps, need confirmation

Are the only specs I need to worry about the voltage and capacity? or do I need to match up the ohms and ripple and variance and color and whatnot?

I'm glad you asked.
When matching capacitors for power supplies, motherboards, and other high-frequency applications that require low ESR caps, the ripple current and ESR/impedance ratings become very important (voltage and capacitance ratings are still important, though).
For power supplies, first match the voltage and capacitance ratings, then try to get as close as possible to the ripple current and ESR/impedance ratings. When matching low ESR caps, make sure that:
1) the ripple current rating of the new caps is the same or higher than the originals
2) the ESR/impedance rating of the new caps is the same or lower than the originals

The ESR and ripple current ratings can be found in the cap's data sheets (use Google or ask here).
If you can't get the right ripple current rating and the ESR/impedance, you can also go up in voltage. This will give you the same capacitance with better ripple current and ESR ratings (that's because within a series of a capacitor brand, the ripple current and ESR depend on the physical size of the capacitor).
Do NOT go with a lower voltage rating, unless you have measured the voltage of the circuit the capacitor will go in and you know that the circuit voltage will never exceed the capacitor voltage rating.

PlainBill also has a very good point about the size - make sure your replacement caps match in size. It's actually okay to get different sizes, but make sure your monitor has the space (if your capacitors are physically bigger, for example).

The green ones are GF series

GF datasheet can be found here:

(I think the data sheet was also uploaded on this forum before, but I found it faster with Google ).

Based on the data sheet, I would recommend any of the following:
Rubycon ZL, ZLG, and ZLJ, United Chemicon KZE, Nichicon HD, and Panasonic FR and FM.
(I encourage you to take any of the above brands and series and check their data sheet to see how it matches to the CapXon GL - this will give you a good idea of how to pick replacement caps in the future)

I notice 2 different types of caps on digikey that seem to fit the specs of these: ones that look very similar to these, and shorter, fatter silvery ones. are those better/worse/different at all?

Hard to say. You do know you can post pictures/links/part numbers here, right?

You mention six different models that should work well, does it matter which ones I get, or are they all good?

No, not really. All of them are high quality Japanese caps and are pretty equivalent in specs. So your choice really.

[aerostarlegacy]

Re: Viewsonic VX1962wm, I think it just needs caps, need confirmation

So, this is what I have so far:

Caps to replace:
1. CapXon gf 220 uf 35v 1060 ripple 10x12.5mm
2. CapXon gf 220 uf 35v 1060 ripple 10x12.5mm
3. capXon gf 2200 uf 10v 1890 ripple 13x20mm
4. CapXon kf 1000 uf 10v 1040 ripple? 8x20mm
5. CapXon kf 22uf 50v 220 ripple 5x11mm

KF datasheet
GF datasheet

I couldn't find the exact cap for #4, so I went with the closest one, does that ripple current sound right?

I'm planning on replacing them with: (digi-key part numbers)
1 and 2: P12411-ND
3: 565-1650-ND
4: P12354-ND
5: P12927-ND

I think I matched them up right, but I would really like a second opinion especially from someone who knows what the heck they are doing.

Also, why doesn't the huge capacitor need to be changed?

Thanks!

[PlainBill]

Re: Viewsonic VX1962wm, I think it just needs caps, need confirmation

So, this is what I have so far:

Caps to replace:
1. CapXon gf 220 uf 35v 1060 ripple 10x12.5mm
2. CapXon gf 220 uf 35v 1060 ripple 10x12.5mm
3. capXon gf 2200 uf 10v 1890 ripple 13x20mm
4. CapXon kf 1000 uf 10v 1040 ripple? 8x20mm
5. CapXon kf 22uf 50v 220 ripple 5x11mm

KF datasheet
GF datasheet

I couldn't find the exact cap for #4, so I went with the closest one, does that ripple current sound right?

I'm planning on replacing them with: (digi-key part numbers)
1 and 2: P12411-ND
3: 565-1650-ND
4: P12354-ND
5: P12927-ND

I think I matched them up right, but I would really like a second opinion especially from someone who knows what the heck they are doing.

Also, why doesn't the huge capacitor need to be changed?

Thanks!

1 and 2: P12411-ND - Check, good
3: 565-1650-ND - Check, good
4: P12354-ND - Check, good
5: P12927-ND - Check, good


These caps handle relatively high current pulses (> 1 amp) at a frequency of (I believe) around 70 KHz. The mains filter cap handles current pulses of less than 1 amp at a frequency of 120 Hz. Each of these pulses generates heat. Because of it's larger physical size and location, the mains filter cap can more easily shed the heat generated, so it doesn't cook itself to death.

PlainBill

[cadillacman]

Re: Viewsonic VX1962wm, I think it just needs caps, need confirmation

doing the caps *should* fix ua up. I had another model viewsonic, same power supply. On mine just the pair of 220uf caps were vented, replaced just those two and its happy.

[aerostarlegacy]

Re: Viewsonic VX1962wm, I think it just needs caps, need confirmation

Thank you all so much for your superb help. I now know much more about capacitors and related stuff. I've ordered the caps, so they should be here thursday or so, then I'll put them in.

Thanks again!

[aerostarlegacy]

Re: Viewsonic VX1962wm, I think it just needs caps, need confirmation

Put the new caps in, and I'm writing this to you on my good-as-new screen! Thanks for all the help guys, I love you!

[Joecm]

Re: Viewsonic VX1962wm, I think it just needs caps, need confirmation

Hi, I'm having the same black screen problem I have replaced the 2) 220 the 1000 and the 2200. but did not work do you think replacing the 22uf will help?
I would also like to replace the nikos p2804nd5g mosfet while I'm at it, is there any US source for purchasing just one or could you recommend a substitute.

Joe

[selldoor]

Re: Viewsonic VX1962wm, I think it just needs caps, need confirmation

It says earlier in the thread to replace all 5 small caps?
and you only need replace the Nikos if after doing that you dont get any screen flash.

[Joecm]

Re: Viewsonic VX1962wm, I think it just needs caps, need confirmation

Thanks Selldoor,
I'll give it a shot.
Joe