My Viewsonic VX924 monitor died!

[NeiltheDruid]

Re: My Viewsonic VX924 monitor died!

Unfortunately, I don't have an analogue multimeter.

Hmmmmm. I'm a bit stuck. What do you wizards think?

[bonney]

Re: My Viewsonic VX924 monitor died!

I would use a analog multimeter set it to times 10k ohm range, then you should get full reading one way and a little reading the other way

[NeiltheDruid]

Re: My Viewsonic VX924 monitor died!

On your multimeter, it is the same function dial as the 2000 ohm setting (which I personally hate).

Correct, does that mean I am doing it wrong? Because no matter what I do, the meter just drops to 000.

[retiredcaps]

Re: My Viewsonic VX924 monitor died!

Ok, I tested the MBR10100CT. No matter which way I put the probes on which ever pins, the reading starts at around "230" and very quickly drop to "000". Basically, almost exactly the same as touching the probes together.

And this is with the multimeter set on the diode test function? On your multimeter, it is the same function dial as the 2000 ohm setting (which I personally hate). You only need the 4 measurements I outlined.

[NeiltheDruid]

Re: My Viewsonic VX924 monitor died!

Ok, I tested the MBR10100CT. No matter which way I put the probes on which ever pins, the reading starts at around "230" and very quickly drop to "000". Basically, almost exactly the same as touching the probes together. Yep, sounds like I'm doing it wrong, but I swear I'm not

[NeiltheDruid]

Re: My Viewsonic VX924 monitor died!

Hmmmm, I've been reading newbie1's thread. Since I'm targeting the SMPS controller on my board. I checked the chip using the pins that newbie1 tested. Pins 1+3 bounced around 16.5-18.6v and pins 1+7 was similar in behaviour but bouncing between 13.5-15.5v.

Since PlainBill stated that the SMPS won't start until pin 7 reaches around 16v, I'm wondering if it actually is the SMPS controller that's dead.

I'll be back asap with the schottky.

[retiredcaps]

Re: My Viewsonic VX924 monitor died!

How do i test this?

With power off and LCD unplugged, set your multimeter on diode test function.

pin 1 = left
pin 2 = middle
pin 3 = right

1) Black probe on pin 1, red on pin 2 record diode measurement
2) Red probe on pin 1, black on pin 2 record diode measurement
3) Black probe on pin 3, red on pin 2 record diode measurement
4) red probe on pin 3, black on pin 2 record diode measurement

A good diode should measure between 0.4 to 0.7 V in one direction and 0L (or "1") in the other.

[NeiltheDruid]

Re: My Viewsonic VX924 monitor died!

How do i test this?

[bonney]

Re: My Viewsonic VX924 monitor died!

it's a MBR10100CT Schottky

[NeiltheDruid]

Re: My Viewsonic VX924 monitor died!

No, I haven't. Is it a voltage regulator?

[bonney]

Re: My Viewsonic VX924 monitor died!

have you checked D660?

[NeiltheDruid]

Re: My Viewsonic VX924 monitor died!

Also, is there a way to test the SMPS controller before I do order a replacement? Since it looks like I'm going to have to order one from way out East.

[NeiltheDruid]

Re: My Viewsonic VX924 monitor died!

Caps are all in correct. Checked the power board and logic board together, nothing. With the jumper removed, it's also the same.

[PlainBill]

Re: My Viewsonic VX924 monitor died!

Hi guys. Just posting back with results of a full recap. Unfortunately, I am getting the same results off the 12vdc out. I'm now guessing that the next suspect would be the SMPS controller?

Darn!!! I'm sorry to hear that.

Before replacing the SMPS controller, there are three tests I would like you to perform.

1. Double and triple check the orientation of the capacitors you installed.

2. Try the power supply without the logic card connected

3. I've circled the ends of the jumper that supplies power to the inverter. Disconnect either end of that jumper. (I believe it is obstructed by a heat sink on the top side). With the logic card connected, try the power supply again.

PlainBill

[NeiltheDruid]

Re: My Viewsonic VX924 monitor died!

Hi guys. Just posting back with results of a full recap. Unfortunately, I am getting the same results off the 12vdc out. I'm now guessing that the next suspect would be the SMPS controller?

[NeiltheDruid]

Re: My Viewsonic VX924 monitor died!

Honestly, avoid eBay for caps unless you know the seller is a good one (referrals through badcaps or other forums) and even then you may get fakes. I'd check out getting Panasonic FC or FM through either Farnell or Radio Spares in the UK, whichever has cheaper shipping.

I would definitely order from digikey, farnell or radio spares, but the cost of the cost of delivery is at least £10 from each of them. I wish they could do a low cost delivery option.

[Wrog]

Re: My Viewsonic VX924 monitor died!

Small question, how can I tell if capacitors are low ESR caps? I am looking at some caps on ebay, they are advertised as "low impedance" is that the same thing?

If the ESR (or impedence) is listed on it's datasheet, then it's probably low ESR (impedence is different, but for this purpose it is close). Honestly, avoid eBay for caps unless you know the seller is a good one (referrals through badcaps or other forums) and even then you may get fakes. I'd check out getting Panasonic FC or FM through either Farnell or Radio Spares in the UK, whichever has cheaper shipping.

[jetadm123]

Re: My Viewsonic VX924 monitor died!

Yes, low impedance is the same as low-esr. On Ebay, just be careful who you order from (especially overseas), since there are sellers that deal in counterfeit caps. Look at the seller's feedback rating carefully.

[PlainBill]

Re: My Viewsonic VX924 monitor died!

OK PlainBill, I'll order a replacement cap for C320. Before I do though, since you suggest that you replace all caps except the filter cap, do you think I should replace the caps I have marked with a green dot, or should I leave well alone?

Yes to both. You will have to slice the heat shrink tubing off the one to identify the value. I'm not sure which part of the world you are in, but in the USA those three caps would cost less than $5.00, including shipping. With a new set of caps I'd expect the monitor to last another 5 years, or until the CCFLs die. At that time you might be able to buy a 26" wide screen with LED backlights for $75.

PlainBill

[NeiltheDruid]

Re: My Viewsonic VX924 monitor died!

Small question, how can I tell if capacitors are low ESR caps? I am looking at some caps on ebay, they are advertised as "low impedance" is that the same thing?