Question about Sony SDM-HS73P 17" LCD Monitor

4 Answers

Monitor won't turn on, no led.

My monitor won't turn on. I am an electronic technician myself, so I started checking. I have both 5 volts and 12 volts from the inverter board that feeds the video board.These voltages are marked on the inverter board. The On/Off line is measuring 0.15 volts, and the Dimming line is 2.6 volts. I also measured 3.3 volts on each side of the power switch, and pushing it makes no difference. I checked the switch itself, and it is good. This tells me that a voltage regulator is working. If the control for turning on this monitor must come from the video board,or must the ON/off line be a voltage developed from the inverter board sent to the video board? If so, this may suggest a problem such as a defective opto-isolator on the inverter board. I cannot find good service literature on this.

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  • ddp-eng Dec 23, 2007

    I have the same issue with the screen on my Sony LCD (SDM-HS73) going black after a few seconds. I have the LHS73K V1.2 chip that rjsoderlund indicated was the dead one. I would like to replace it if I could with the V1.3 chip referred to. Does anyone know where I can find one to buy?

  • timo16 Feb 15, 2008

    where can I find the part LHS73k ver 1.3



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If you have a monitor which has an external power that power supply can be substituted for another one by soldering the positive and negative cords to the back of the circuit board, but I found out that I have to stick something into the power jack to push down a contact thing so that it does not connect with another part of the jack that shorts the connection. I found this out on my own just now. Free lcd monitor, didn't work because it had no power supply and the power button was busted. I am going to school to be a computer engineer, sorry if I don't have the right terminology.

Posted on Aug 01, 2010

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Hi guys, just been reading your posts on the symptoms regarding this montor. I have a very similar problem whereby, no power light is displayed and monitor is totally dead. Any idea where i can get a replacement graphics card? My chip states LHS93K v1.0 THANKS ALL

Posted on Jun 01, 2008

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I am having the same problem with one of these monitors, however, i'm in a unique situation. I have one that works and one that doesn't.

I narrowed it down to being the power controller / video signal processing circuit board in this LCD. When I swapped this part alone (after checking the power supply very carefully), the dead monitor came to life. The model number of this part (Manufactured by LG, NOT SONY) is LHS73K. The Version 1.2 is the dead one, the version 1.3 is the good one. Even though the plastic connectors are slightly different, the pinouts are the same and the pins do line up, so I swapped the controllers, and the dead monitor came to life. I notice the dead controller card's GENESIS IC gets slightly warmer than it does with the working one.

I took some high resolution pictures of the 2 cards, and highlighted (light yellow boxes) some differences....

(i'm hosting the pictures on my own file server because they are 1.5mb each, and fixya puts a limit on the file size you can attach a picture with)

Working v1.3 Image: <url></url>
Dead v1.2 Image: <url></url>

I am going to do some more work and see if I can bypass the soft-switch with a hard-switch to turn the power supply on in the dead monitor, if that works, i'll update the post and let everyone know what and how I did it.

Posted on Nov 27, 2007

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If the LCD has an internal power supply, then the inverter circuit should be on the board as the power supply. If the power supply is external, then the inverter circuit will have it own board.

What is the output of the Inverter circuit? It should have 12VDC going in, but around 50VAC going to the CCFL bulbs.

The "no led" should be a sign. Your getting voltage, but what about current? It still can be the power supply. All LCD monitors should have a "soft switch", or software driven switch to turn the CCFL lamps on and off.

It is hard to find literature on LCD repair, experience is the best teacher on this subject. This might take several emails or postings to help find the answer.

LCD monitors are a computer. You can break them into several parts, Power, I/O, and processing. Power is the easiest to trouble-shoot and repair. Processing is the hardest.

I fixed one LCD monitor by re-seating the software EEPROM. The process could not do its job if it can not read the software EEPROM.

If one of your IC's is shorted, you can always tell using a can of air. Get one of those cans of air and tip it upside down and spray the entire board until it all turns white. Now apply power to the system. If an IC is shorted, it generates more heat than anything else. It will be the first to loose the white condensation. Don't worry this is safe, done it several times.

Posted on Nov 16, 2007

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Smps on but display not showing

A) Check the monitor cable on a KNOWN to be working computer,
Use the monitor cable from the working computer on yours.

Monitor cable does not remove?
Use the monitor, AND monitor cable; on a KNOWN to be working computer.

B) SMPS may have a weak voltage power rail

[There are 3;
A) 3.3 Volts
B) 5 Volts
C) 12 Volts
ALL are DC Voltage.
In comparison two D cell flashlight batteries produce 3 Volts DC ]

1) If ALL of the LED lights were on at once, they would use less than 1 Watt of power.

2) EACH fan uses 2 to 3 Watts of power.

3) A typical Processor (CPU) can use 51 to 125 Watts of power.
Just depends on what Processor it is.

This is why you may see LED's light, and maybe fans spin, but NOT enough power to turn the Processor on.

Use a multimeter set to DC Voltage, and check the 3 power rails.

ALL Orange wires you see are 3.3 Volts
ALL Red wires are 5 Volts
ALL Yellow wires are 12 Volts
ALL Black wires are Ground wires

Use a KNOWN to be good, Compatible power supply; for a temporary test unit.

Also, FOLLOW Anti-Static Procedures, with your unplugged from power computer.
DO NOT reach inside your computer if you are not.
Do not know what Anti-Static Procedures are?
Post back in a Comment.

PLUS, remove the Ram Memory modules ('Stick'), and reinstall them. One of them may be bumped loose.

NO. You cannot see it by eye alone. Remove, and reinstall.
This way you are ASSURED they/it, are installed tightly, and correctly.

For additional questions please post in a Comment.

Mar 13, 2013 | ASUS P4P800 Deluxe Motherboard

1 Answer

The hard drive is plugged in and there is nothing showing on the screen

Motherboard illustration and motherboard photo towards bottom of page.

First thing to check is power.

Check the 3 main voltage power rails.
3.3 Volts, 5 Volts, and 12 Volts. (All are DC Voltage)
Check with a multimeter.
(In comparison two D cell flashlight batteries store 3 Volts DC)

LED's can light, fans can spin, but there may not be enough power to turn the Processor on.

1) If ALL if the LED's were on at once, they would use less than 1 Watt if power.

2) EACH fan uses 2 to 3 Watts of power.

3) A typical Processor can use from 51 to 125 Watts of power. Just depends on what Processor it is.

[TDP = Thermal Design Point. Under this heading is stated what the maximum Wattage is, that the Processor can use Up To ]

The monitor screen receives a video signal from the computer.

When the monitor does Not receive a video signal, No Signal is shown on the monitor, or the monitor may go into Sleep Mode, or Power Saver Mode.

For additional questions please post in a Comment.


Oct 08, 2012 | HP Compaq Presario SR1215CL (82916052980)...

1 Answer

Need help from someone who has a Gateway GM5072 Desktop

Monitor, and monitor cable has been checked out, on another KNOWN to be working computer, and check good, check the Power Supply.

1) Yes I know logic dictates graphics should come next, after checking the monitor, and monitor cable.

2) Yes I know LED lights are lit, and fans are spinning.

Hear me out;

A) If ALL of the LED lights were on at once, they would use less than 1 WATT of power.

B) EACH fan uses 2 to 3 Watts of power.

C) A typical Processor can use 51 to 125 Watts of power. Just depends on what Processor it is.

Gateway GM5072 Desktop PC?

Specifications >
Processor: AMD Athlon 64 X2 4200+

Look under TDP in the chart. (Thermal Design Point)
Can use Up To 89 Watts.

Your Power Supply could have a weak voltage power rail.
Not enough power to turn the Processor on.

(There are 3 main voltage power rails;
A) 3.3 Volt power rail
B) 5 Volt power rail
C) 12 Volt power rail
Your Power Supply is a converter. Converts 100 to 240 Volts AC to the low DC voltages presented above.
{In comparison two D cell flashlight batteries store 3 Volts DC )

No Processor operating, no computer operating. No computer operating, there isn't going to be a video signal produced by the computer.
This = No Signal on monitor, or monitor goes into sleep mode.

You press the Power On button. The plastic assembly of the Power On button, presses against the Power On switch contained inside it.

The Power On switch is a Momentary Contact Switch.
The brief closing of the Power On switch closes a circuit.
The Soft Power On circuit.
(Abbreviated as PS_ON)

When the Power Supply is plugged into power, there is a constant 5 volts present, in the Power Supply.
The 5 Volt Standby Power.

Closing the Power On switch briefly redirects the 5 volt standby power, to 'excite' the Power Supply, and turn the Power Supply on.
(Sounds like a steamy novel, huh?)

The first chipset (I.C.) to receive power is the BIOS chipset.

The Basic Input/Output System program is initialized.
BIOS looks to see what devices are installed, does a Ram Memory count, TURNS the Processor on, and hands the computer over to the Operating System.
(Windows XP and Windows 7 are two examples of an O/S.

The TWO main problems for desktop computer failure, is the computer is dirty inside, and Power Supply failure.

Do you have a multimeter, or access to one?
If not, do you have access to a KNOWN to be good, Compatible power supply, that you could briefly use for a test unit?

[An economical multimeter can be purchased for around $5 to $12. Available in a multitude of stores. An auto parts store is but one example. A lot of chain stores carry them. ]

Let's check out the power first. Post back in a Comment.


Aug 15, 2012 | Gateway GM5072 Desktop PC

1 Answer

T6528 has no video. Using a working monitor, tried differnet video cards but still no video.

1) So you tested the monitor on a working computer? Reason I ask, is that you will be testing the monitor cable also.

If it is a monitor with a detachable monitor cable, suggest you test the cable also.

2) Each graphics (Video) adapter card has it's own specific driver.
The driver should be installed Before, the graphics card is installed.

Otherwise Windows will 'break it's neck', to find a compatible driver, from it's thousands of generic drivers.
Won't do. You will get a driver conflict.

Windows: 'Which driver do I use? These or THESE?"

Kinda' hard to do, since you can't see graphics on the monitor.

I would like to suggest you diagnose the Power Supply to start with. (After checking the monitor cable)

It may seem that the Power Supply is okay, but it could have a weak Voltage power rail.

Enough power to light LED lights, and spin fan's, but not enough power to turn the Processor on.

1) ALL the LED's use less than 1 Watt of power.

2) EACH fan uses 2 to 3 Watts.

3) A typical Processor can use 51 to 125 Watts.
(Lower for older Processors)

The eMachines T6528 comes with an AMD Athlon 64 3500+, processor, that fits in a Socket 939 processor socket,

1) eMachines Support > T6528 > Specifications,

2) Information on the AMD Athlon 64 3500+,

Can use up to 67 Watts, or up to 89 Watts. Depends on what Core it is.
(Clawhammer Core, Newcastle Core, Winchester Core, Venice Core, Manchester Core, or San Diego Core)

(Also uses an MSI K8NGM-L motherboard. Below for specifications only, )

A) Not to down eMachines, (I have an old T1090 in my shop that works great), but they are budget computers, and use budget parts.
One being the generic Power Supply that is used.

B) The computer could be dirty inside, as well as inside the Power Supply.

The cooling components for the SMPS, (Switched-Mode Power Supply,) are it's Fan, and Heatsink's used inside.

Once a layer of 'Gunk' covers these cooling components, the cooling capacity drops tremendously.

Heat = Wasted Energy

The more heat, the more the Power Supply strains to keep up with the call for power.
Eventually hardware components inside the Power Supply fail, and the Power Supply is toast.

You can test the Power Supply voltages.
You can use a multimeter if available, or an economical unit can be purchased for around $5 to $12, that will suffice for testing.

You can also use a power supply tester.
One example:

Voltages produced by the SMPS used in a T6528 are,
A) 3.3 Volts (DC)
B) 5 Volts (DC)
C) 12 Volts (DC)

Testing should be done on the 12 Volt power rail.
11 to 13 Volts indicates a good Power Supply.
Less than 11 Volts means it's time to replace.

Orange wires are 3.3 Volts
Red wires are 5 Volts
Yellow wires are 12 Volts.

All the color coded Voltage wires, lead back to one individual power rail, for each Voltage produced by the Power Supply.

You can test any Yellow wire to test the 12 Volt power rail.

With a multimeter, the Positive (Red) probe lead connects to the power wire to be tested.

The Negative (Black) lead connects to ANY Ground wire.

ALL Black wires are Ground wires.
They all go back to one central Ground source inside the Power Supply.

[Power Supply unplugged from power before attaching probe leads. After connecting, the power supply is plugged back into power, and the Power On button is pushed ]

(Two C cell flashlight batteries produce 3 Volts DC)

Jun 20, 2010 | E-Machines T6528 PC Desktop

1 Answer

I have a 5-year old Sony 19-LCD monitor that stopped working. The little power-on light does not come on, and their is no picture, but I do hear a faint buzzing from the back. Sounds like?

smyko, Sounds like a tired out old "switch-mode-power-supply"/ "inverter CCFL power-supply!!! May require unit to be REFURBISHED with upgraded power suppllies and if the LCD screen had been displaying an increasingly dimmer screen, it may also need new "cold cathode-fluorescent lamps" installed. A technician who knows all about LCD monitors and their backlight "ELECTRONIC BALLAST" circuits will need to evaluate it. Check with sony and find out if you can do a "cash+old unit swapout for a factory rebuilt (refurb) same model type. Before you do any of that have a look at youtube for longer video clips of "LCD monitor disassembly" and "LCD monitor repair" just FYI. You will then know and understand what is on the "OTHER SIDE" of what you been looking at for 5yrs!!! Yes, they are trying to experiment with WHITE led arrays that won"t fail for 10 years. Remember lcd Panels last 8 - 12 yrs. Hope this helps. Bye for now. 12fixlouie

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1 Answer

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This monitor is know for a lot of parts that go bad, luckily they are usually the same ones.
If you are a technician or know one who can help you. Below is a list of part to repair/replace once the case is opened. (dont try this if your unfamilier with working on electronics.

1) F601= 2A Fuse
2) C605= 68uf 400v (must change)
3) R615= 0.68ohm 1watt
4) Q601= SSS6N60A
5) R613= 1Kohm 1/8watt (value changed to 2.3Kohm or higher)
6) R623= 4.7ohm 1/8watt (value changed to 7.2ohm or higher)
7) D604= 1N4148
8) IC601=UC3842B
9) C707 & C703= 1000uF 16V (must change, because of bad ESR value) secondary filter capacitor.
This problem of dell e151fp lcd monitor, you just need to resolder the inverter section (bad points or dry joint) and also check the capacitor value with ESR meter. It will solve your problems.

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have you tested the power supply connection feeds? test each connector I think you will find your power supply has failed on either the 5 volt or the 12 volt side more than likely 5 volts are down' the agp adapter needs 5 volts to run. since you have changed out every thing else I would replace that or test your dads power supply in your computer, that should do the trick

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Your inverter power supply has gone bad. You will need to replace the whole board or replace the the 2sc5707 transistors in the inverter area. Check out this link for installation videos and how to for that model
They also sell the whole board as well as repair kits

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