Viewsonic vx2235 with bad caps

[gregmcc]

I've got a faulty Viewsonic VX2235 with the classic bulging caps problem. From some of the posts I've read guys have replaced the same 2 cap's that I have bulging and its sorted out their problem.

I've replaced the caps and it still has the same symptoms.

Faulty caps:
Capxon
1000uF 25V
105C
P630
VENT

I've replaced them with:
JWCO
1000uF 25V
105C
VENT

From further reading up I've now learnt a cap is not a cap and if it doesn't have the right ESR it will never won't work.

I suspect its because I'm not using the right caps. Correct? So my question is how do I know if the above cap is a good equivalent. I"m unable to find Capxon caps locally.

[retiredcaps]

Re: Viewsonic vx2235 with bad caps

I suspect its because I'm not using the right caps. Correct? So my question is how do I know if the above cap is a good equivalent. I"m unable to find Capxon caps locally.

Capxon is a hated name here. We recommend Rubycon MCZ, Panasonic FC or FM, and/or United Chemicon.

You may have more problems than just bad caps.

Post clear focused pictures AFTER reading

https://www.badcaps.net/forum/showthread.php?t=1868

DO NOT post pictures inline.

Take your boards to a window on a sunny day, turn flash off, and use macro mode. Take a top down view of all your boards (front and back). Make sure the photo is legible so that we can read the PCB printing clearly. A shutter speed of 1/125 or faster will produce nice clear focus pictures. Try to get a photo that is 2000x2000 resolution or as close as possible.

Here is an example of the pictures we want.

https://www.badcaps.net/forum/showpo...94&postcount=1

[gregmcc]

Re: Viewsonic vx2235 with bad caps

Ahh - I found this thread which explains all

https://www.badcaps.net/forum/showthread.php?t=2280

I'll see f I can locate one of these brands and provide feedback

[gregmcc]

Re: Viewsonic vx2235 with bad caps

Here is an example of the pictures we want.

https://www.badcaps.net/forum/showpo...94&postcount=1

Thanks - I"ll post pics asap.

[PlainBill]

Re: Viewsonic vx2235 with bad caps

I've got a faulty Viewsonic VX2235 with the classic bulging caps problem. From some of the posts I've read guys have replaced the same 2 cap's that I have bulging and its sorted out their problem.

I've replaced the caps and it still has the same symptoms.

Faulty caps:
Capxon
1000uF 25V
105C
P630
VENT

I've replaced them with:
JWCO
1000uF 25V
105C
VENT

From further reading up I've now learnt a cap is not a cap and if it doesn't have the right ESR it will never won't work.

I suspect its because I'm not using the right caps. Correct? So my question is how do I know if the above cap is a good equivalent. I"m unable to find Capxon caps locally.

You are probably correct. And there may be additional problems. one of the 'wits' here refer to them as Crapxon, a scatological reference. (If you don't understand it, you have had a good upbringing).

Personally, I prefer Panasonic FM or FC series caps. The FAQ entry 'Which caps should I buy' lists other brands and series as good or better.

PlainBill

[gregmcc]

Re: Viewsonic vx2235 with bad caps

I've replaced the bad caps with Rubycon YXF caps and the problem still persists

Its got all the symptoms of the bad caps problem - if I shine a light on the monitor I can see the image faintly.

[jetadm123]

Re: Viewsonic vx2235 with bad caps

1) Did you replace ALL (except for the large one) the caps? Caps don't have to be bulging in order to be bad. Looks like you still need to replace maybe 4 caps? Also replace the small 22uf? cap, it's part of the startup circuit.

2) After replacing the caps and connecting the boards and backlights, if the problems persists, check the output voltages at the 8-prong plug connecting the boards together. Check for the 5 and 12 volts and report your findings.

[retiredcaps]

Re: Viewsonic vx2235 with bad caps

if I shine a light on the monitor I can see the image faintly.

Did you check F200 (fuse)? It should read around 0.3 ohms on your multimeter.

[jetadm123]

Re: Viewsonic vx2235 with bad caps

Did you check F200 (fuse)? It should read around 0.3 ohms on your multimeter.

Good catch by retiredcaps. If F200 is blown, it's most likely caused by one of the two 8-pin AOP605? chips (located to the right of the top inverter transformer) shorting out.

[seanc]

Re: Viewsonic vx2235 with bad caps

Do your backlights ever come on?

When we have this fixed, can you see if your PSU emits a whine when in standby? Mine is driving me crazy.

[gregmcc]

Re: Viewsonic vx2235 with bad caps

Thanks for the tips - I've not replaced all the caps. I'll try that and provide feedback with the measured voltages.

[gregmcc]

Re: Viewsonic vx2235 with bad caps

I've replaced all the caps and checked the fuse - still no luck.

I"ve also checked the voltages on the 2 x 8 way plug

First row on pins:
0
0
3.1
5
0
4.6
0
0

2nd Row:
2.6
0
0
5
14.2
4.5
0
0

Anything else I can check?

[retiredcaps]

Re: Viewsonic vx2235 with bad caps

Anything else I can check?

What is the part number of U202 and U203? These are the 8 pin ICs just right of the two transformers.

They could be shorted?

[gregmcc]

Re: Viewsonic vx2235 with bad caps

what is the part number of u202 and u203? These are the 8 pin ics just right of the two transformers.

They could be shorted?

u202:
P605
bd6n2b

u203:
P605
bd6n4d

[retiredcaps]

Re: Viewsonic vx2235 with bad caps

u202:
P605

Datasheet at


With power off and lcd unplugged, put your multimeter (if it is manual range) to 200 (two hundred) ohms. If it reads 1 on the left hand side, just record 1.

Refer to datasheet for pinout diagram.

Test S1-G1, S1-D1, G1-D1. Note there are 2 D1s.
Test S2-G2, S2-D2, G2-D2. Note there are 2 D2s.

If my math is right that should be 12 readings for each chip. Please list them all for both IC chips.

[gregmcc]

Re: Viewsonic vx2235 with bad caps

Both chips give the same readings. I've also checked the diode across D/S - its open the way one and .5 the other.

S1-D1:1
G1-D1:1
G1-S2:1
S2-D2:1
S2-G2:1
D2-G2:1

[retiredcaps]

Re: Viewsonic vx2235 with bad caps

2nd Row:
2.6
0
0
5
14.2
4.5
0
0

Is there a more specific marking on the back cover? Like vx2235-4 or vx2235wm-3?

There are service manuals available at

http://ftpkuban.com/FTP/Manual/ViewSonic/

and two of the ones that I looked through suggest it should have 24V DC. If you have a manual range multimeter and set it to 20V DC, you may not have gotten correct readings on these connector pins?

Also, one other question that hasn't been answered yet.

A member asked if the screen flashes at all? Or is it just black the entire time. It matters.

[jetadm123]

Re: Viewsonic vx2235 with bad caps

I've replaced all the caps and checked the fuse - still no luck.

I"ve also checked the voltages on the 2 x 8 way plug

First row on pins:
0
0
3.1
5
0
4.6
0
0

2nd Row:
2.6
0
0
5
14.2
4.5
0
0

Anything else I can check?

The ID or voltage is usually silk screened on the board next to the row(s) of pins. Can you equate what's on the board to each pin above?

[retiredcaps]

Re: Viewsonic vx2235 with bad caps

On the back side of the power board, IC 200 is an 18 pin chip. What is the part number? I can't quite make it out. Is it OZ9616N?

This is the inverter IC. It controls the backlight function.

We will have to find its datasheet to know what the pinout is and then measure the voltages.

[gregmcc]

Re: Viewsonic vx2235 with bad caps

When I switch the monitor on it flashes on and off for a fraction of a second and I can briefly see the correct grahpics on the screen. Then all goes dark.


IC200 is a 20 pin chip:
OZ964GN

I've also had a look at the service manuals - The manufacturing date on the monitor is Sept 2006 so I think the vx2235wm-1 is the closest with a date of Aug 2006 however I can't seem to see the inverter circuit on the -1 pdf.

From the silkscreen I can make out the following:
gnd
5v
13.8
mute
aor-
aol+

and on the other pins:
eva
gnd
det
5v
v_ad
shut
aor+
aol+