VX 724 black screen green light flashing

[budm]

Re: VX 724 black screen green light flashing

I cut the legs and add more solder to the tab, the trick is to use wide tip soldering iron with at least 40watts.

[Nocta]

Re: VX 724 black screen green light flashing

Great. I took the coil and some caps off because the space is reduced. After that, I desoldered the VR

[retiredcaps]

Re: VX 724 black screen green light flashing

I'm trying but I can't desolder the VR.

From the same referenced thread in post #66

https://www.badcaps.net/forum/showpo...3&postcount=26

[Nocta]

Re: VX 724 black screen green light flashing

I'm trying but I can't desolder the VR. I guess I'll just have to wait and buy a rework station. I've been waiting for it for almost 20 days. There're some troubles importing products.

[retiredcaps]

Re: VX 724 black screen green light flashing

I'm gonna buy new voltage regulators on Monday, they're not expensive at all.

Desolder the old ones and verify they are shorted out of circuit.

I have a Dell monitor and both voltage regulators on the logic board are shorted. So it is not the first time that all the voltage regulators on a board have been shorted.

[Nocta]

Re: VX 724 black screen green light flashing

The original part number has no suffix to denote an output voltage so it sounds like an adjustable voltage regulator not a fixed one.

I looked at the service manual for the logic board power supply section, it looks like it uses the adjustable 1117 series, it also has 5v step-down switching regulator also so you may want to check those caps.. The stuff in the dash line are not used, I believe.

I fully recapped the board, so caps are new and working. I'm gonna buy new voltage regulators on Monday, they're not expensive at all.

Thanks!

[budm]

Re: VX 724 black screen green light flashing

I looked at the service manual for the logic board power supply section, it looks like it uses the adjustable 1117 series, it also has 5v step-down switching regulator also so you may want to check those caps.. The stuff in the dash line are not used, I believe.

[retiredcaps]

Re: VX 724 black screen green light flashing

Is it OK if I replace it with AS-1117? It's a 3-pin voltage regulator and the output is 3.3v and 800mA.

The original part number has no suffix to denote an output voltage so it sounds like an adjustable voltage regulator not a fixed one.

[Nocta]

Re: VX 724 black screen green light flashing

Okay then, I'm gonna find these voltage regulators on the market because if I buy them on eBay, it'll take at least 15 bussiness days.
But first of all, I'll have to look for the number of the resistors.


I found the service manual for this monitor. It says that if the display color is "abnormal" then I should check U3 (which is a voltage regulator). I'm looking at the diagrams and it seems that VR are shorted, the output should be 3.3v insted of 2v ...

Is it OK if I replace it with AS-1117? It's a 3-pin voltage regulator and the output is 3.3v and 800mA.

[retiredcaps]

Re: VX 724 black screen green light flashing

@retiredcaps - he has a picture its just a bit fuzzy -would he get that if all 1117s are shorted or he had a short on the board

I believe it is possible. Just a couple of days ago we had this case of a shaky jittery image due to a voltage regulator running at 1.2V instead of 1.8V DC. So if the 1117s are supposed to output 1.8V and they are outputting 2.0V, it could cause fuzziness.

https://www.badcaps.net/forum/showthread.php?t=19936

[selldoor]

Re: VX 724 black screen green light flashing

@retiredcaps - he has a picture its just a bit fuzzy -would he get that if all 1117s are shorted or he had a short on the board

[retiredcaps]

Re: VX 724 black screen green light flashing

Pin 1: 13,2v AC --- 2v DC
Pin 2: 13,2v AC --- 2v DC
Pin 3: 13,2v AC --- 2v DC

1117 voltage regulators output DC voltage (not AC). Put your black probe on a ground screw. Put your red probe on each pin. Put your multimeter on 20V DC if manual. Retest and report new readings.

If your readings are actually 2V DC for each pin, then all your voltage regulators are shorted. That would make sense since pin 1-2 readings are 0 ohms. Alternatively, something else on the logic board is shorted making it look like all your voltage regulators are shorted.

[Nocta]

Re: VX 724 black screen green light flashing

I see a couple voltage regulators (3-pin device) on the left side of the logic board below the Toroid choke. Please the number and the voltage reading on 3 pins. Also try heat up the logic board with hair dryer to see if it changes the picture quality after 2~3 minutes of heat.

I can't read the number but It says something like "xxx 5FAL - 1117L".

The readings are (with the black lead on ground)

Vr1

Pin 1: 13,2v AC --- 2v DC
Pin 2: 13,2v AC --- 2v DC
Pin 3: 13,2v AC --- 2v DC
Pin 2-1: 0 Ohm
Pin 2-3: 197 Ohm

Vr2

Pin 1: 13,2v AC --- 2v DC
Pin 2: 13,2v AC --- 2v DC
Pin 3: 13,2v AC --- 2v DC
Pin 2-1: 0 Ohm
Pin 2-3: 197 Ohm

Vr3 (on the board with the VTI 03601)

Pin 1: 13,2v AC --- 2v DC
Pin 2: 13,2v AC --- 2v DC
Pin 2-1: 0 Ohm
Pin 2-3: 127 Ohm

(From the power board, LEFT to RIGHT).

I don't have a hair dryer. Is it the same if I use my hot air gun?

Jumper should be on 6.5 for a 17 inch panel

https://www.badcaps.net/forum/showthread.php?t=14776

Thanks!

[selldoor]

Re: VX 724 black screen green light flashing

Jumper should be on 6.5 for a 17 inch panel

https://www.badcaps.net/forum/showthread.php?t=14776

[budm]

Re: VX 724 black screen green light flashing

I see a couple voltage regulators (3-pin device) on the left side of the logic board below the Toroid choke. Please the number and the voltage reading on 3 pins. Also try heat up the logic board with hair dryer to see if it changes the picture quality after 2~3 minutes of heat.

[Nocta]

Re: VX 724 black screen green light flashing

LOL. The original caps are TEAPO and the ones on the board I bought are Taicon.

I changed the jumper, means I changed its position (to 7 and 7,5mA) and still the image is not good.

I changed a couple of caps from the logic board but not all of them (yet). I'm working on that.

Thanks for your input!

[selldoor]

Re: VX 724 black screen green light flashing

Ohhhh! when you said green I immediately thought Teapo or Taicon. They are usually replaced on sight. Can you post pictures of your boards.

"Changed the jumper and nothing." do you mean no change or nothing?

[Nocta]

Re: VX 724 black screen green light flashing

Ok, so I cleaned the ribbon cable with isopropyl alcohol and nothing. Changed the jumper and nothing.

The caps of the power board are Taicon.

[Nocta]

Re: VX 724 black screen green light flashing

I had the "2 seconds to black" problem with my old board. The 2 seconds I had image, it was just like now but I thought it was the power/inverter board but now I realize it was not.
The old board had no jumper for the lights. The board is the same but a different model. The partnumber seems to be the same (unless it's a fake) but clearly a different model. For example, the main cap filter is 100uF and the original board had a 150uF. Plus, it has a big transformer for the 4 light connectors. The other one had 2 little transformers.
I don't know the brand of the caps on the new board. They were green.

I tried also with a VGA cable (now it's connected with a DVI cable) and I had the same result.
The PC is not the problem either because my other monitor works just fine. I connected this monitor (Viewsonic) to my laptop and same thing.

I'll try cleaning the Ribbon cable. Is it OK if I use isopropyl alcohol?

EDIT: Caps are Taicon.

[selldoor]

Re: VX 724 black screen green light flashing

I have not really followed this thread but The new power board you bought did it look as if it had been reworked. What make /series caps does it have in?

Did you re cap the video board and again what caps did you use?

Did your old board have the jumper for the lights - if so what was that set at?
This should be set the same? having said that the problem you have doesnt really look like its related to the brightness of the ccfls.

Have you tried a factory reset.

If the your old board did not have the power jumper - have you bought the correct board?


Is the pc set at the optimum resolution for the screen

Have you done the normal power board checks on the new board - voltage on main cap and output voltages.