Yusmart 229IP-P 22" LCD Monitor Dead

[fusionmax]

Hi all,

I have aquired a Yusmart 229IP-P 22" LCD monitor that has no power. When pressing the power button nothing happens at all.

I have stripped the monitor down and done some research and the power board appears to also be used in Viewsonic VS11446, I have included some links below.....

http://www.shopjimmy.com/power-suppl...ic-vs11446.htm
http://item.taobao.com/item.htm?id=6880290874

I have done a visual inspection of the board and all of the capacitors look good with no bulges or leaks, they are 'Hermei' brand.

I also managed to find a service manual for the Viewsonic monitor with the same power supply, this can be found at this link

Please can somebody advise me on my next move?

[jetadm123]

Re: Yusmart 229IP-P 22" LCD Monitor Dead

Is there a reason why you removed the main fuse located to the left of the power plug?

With the fuse in place, your next step would be to check the voltage across the large brown cap (lower right corner). BE CAREFUL as this is HIGH VOLTAGE! If you're in the USA the voltage should be approx 165VDC.

[fusionmax]

Re: Yusmart 229IP-P 22" LCD Monitor Dead

Forgot to mention I removed the fuse to test it

I am in the UK so what should the voltage be?

I have a standard digital multi-meter, will I be ok using this to test or will the voltage be too much for it?

[jetadm123]

Re: Yusmart 229IP-P 22" LCD Monitor Dead

Forgot to mention I removed the fuse to test it

I am in the UK so what should the voltage be?

I have a standard digital multi-meter, will I be ok using this to test or will the voltage be too much for it?

Whatever your outlet voltage is x 1.4

IE, in the US, outlet voltage is 120VAC x 1.4= 168VDC

[fusionmax]

Re: Yusmart 229IP-P 22" LCD Monitor Dead

Ok, I measured the voitage at the brown cap and it gave me a reading of 322volts which is 1.4*230

So everything is ok so far?

[fusionmax]

Re: Yusmart 229IP-P 22" LCD Monitor Dead

Are there any other points I can check voltages at?

[retiredcaps]

Re: Yusmart 229IP-P 22" LCD Monitor Dead

Are there any other points I can check voltages at?

For fuses, you can test them "in circuit" (power off and LCD unplugged) and get a reading. A good fuse should measure below 1.0 ohms depending on your multimeter.

You can now test for secondary voltages on the connectors that go to the logic card. You should see something like 5V DC and/or 12V DC, 3.3V DC depending on the design. Use a ground screw for your ground (black probe).

Report the voltage measurements.

If you see none of those voltages, we will need a clear focused picture of the backside. On the backside, there is likely to be a 8, 12, or 16 pin IC. We will need the part number for that chip.

[fusionmax]

Re: Yusmart 229IP-P 22" LCD Monitor Dead

I have tested the voltages using my multimeter and included them below, I seem to be getting 5v from 3 points.

[retiredcaps]

Re: Yusmart 229IP-P 22" LCD Monitor Dead

I have tested the voltages using my multimeter and included them below, I seem to be getting 5v from 3 points.

Okay, voltage should be getting to the logic board if you see 5V DC.

Does the power LED turn green or any other color when power is applied?

Also, please post a picture of the logic board (top down view) both sides.

[jetadm123]

Re: Yusmart 229IP-P 22" LCD Monitor Dead

I have tested the voltages using my multimeter and included them below, I seem to be getting 5v from 3 points.

Looks like the 5V output is working correctly. Brown wire should read 24v. With power off, check diode pack D821? (at top, mounted to heatsink) for shorts.

[fusionmax]

Re: Yusmart 229IP-P 22" LCD Monitor Dead

The power LED does nothing when it is pressed or the power lead is plugged in.

How would I go about checking the diode at D821? Would I need to remove it from the board to test it with my multimeter?

I have also attached some hi-res pictures of both the front and back sides of the PSU board and logic board.

[retiredcaps]

Re: Yusmart 229IP-P 22" LCD Monitor Dead

How would I go about checking the diode at D821? Would I need to remove it from the board to test it with my multimeter?

Check the diode "in circuit" first. If the readings are suspicious, then you will have to remove it and retest.

If it is a dual diode, it should have two diode symbols pointing at each other towards the middle pin (pin 2).

Put your multimeter on ohms scale. With power off and lcd unplugged.

1) put red on pin 1, black on pin 2. report ohms.
2) put red on pin 3, black on pin 2. report ohms.
3) put red on pin 1, black on pin 3. report ohms.

Now switch to diode mode setting on your multimeter.

1) put red on pin 1, black on pin 2. report volts.
2) put black on pin 1, red on pin 2. report volts.
3) put red on pin 3, black on pin 2. report volts.
4) put black on pin 3, red on pin 2. report volts.

edit1: PS. What is the part number of that IC chip right in the middle of the power board (backside)?

edit2: Test both dual diodes. One is for the 5V and the other is for 24V DC or 19V DC. We don't know which is which.

[Rtech]

Re: Yusmart 229IP-P 22" LCD Monitor Dead

Put your meter to resistance 2k Range..there should be a short circuit between the outside pins(you should see them connected together on the bottom of the board.Then go from the centre pin to each outside pin in turn,Reversing the red and black wires of the meter...and you DO NOT want a short circuit ??

[fusionmax]

Re: Yusmart 229IP-P 22" LCD Monitor Dead

Hi,

I am fine with the diode mode, as that is the option with the diode symbol But when you say put the multimeter on the ohms scale, what exactly do you mean?

My multimeter has 5 options in the ohms section, they are...

• 2000k
• 200k
• 20k
• 2000
• 200

Which one should I be going for?

I have also managed to find what the two diodes are and the datasheets for them if that helps?

D821 - DIODE,SCHOTTKY FCH10A20 TO-220AB NI - datasheet
D822 - DIODE,SCHOTTKY SB1060FCT TO-220AB PEC - datasheet

The IC on the power board says...

7575
1439

[retiredcaps]

Re: Yusmart 229IP-P 22" LCD Monitor Dead

My multimeter has 5 options in the ohms section,

Which one should I be going for?

2000 (two thousand) as per Rtech in post #13.

[retiredcaps]

Re: Yusmart 229IP-P 22" LCD Monitor Dead

Just found the schematic, I think. I searched for godo gdp-003 and found a post here

https://www.badcaps.net/forum/showth...hlight=gdp-003

which suggests it uses the same board as a VX2235WM-3. That leads to



On page 46, it is definitely D821 that supplies the 24V DC. If the diode tests good, then I suggest measuring the voltage on pin 2 (put black on a ground screw). You should get 24V DC.

If you do, then either or all C822 C829 C823 are likely suspects. Even though they show no visible sign of distress, they can have high ESR (ohm) or be out of uF tolerance.

[fusionmax]

Re: Yusmart 229IP-P 22" LCD Monitor Dead

I tested pin 2 with the power applied and got nothing. Maybe the diode is bad then?

[retiredcaps]

Re: Yusmart 229IP-P 22" LCD Monitor Dead

I tested pin 2 with the power applied and got nothing. Maybe the diode is bad then?

Try the diode tests in post #12 and #13 and report back.

[retiredcaps]

Re: Yusmart 229IP-P 22" LCD Monitor Dead

I tested pin 2 with the power applied and got nothing. Maybe the diode is bad then?

Just to verify. You had black probe on a ground screw and red probe on pin 2? And measuring for DC V?

Is your multimeter a manual range one? If yes, you will need to set it for 200V DC since you are looking for 24V DC.

[fusionmax]

Re: Yusmart 229IP-P 22" LCD Monitor Dead

Sorry, its a manual range one. Just tried again...

With the multimeter set at 200 DCV, the black probe on a ground screw and the red probe on pin 2 of D821-FCH10A20 it read 27.1