Faulty Flat Screen Monitor

[ljcox]

I have a CMV CT-712A, Model A170E1-OA flat screen monitor.

Recently, the power supply of the computer to which it was connected blew up. There was a bang & flash from its switching mode power supply unit (PSU) when I turned the mains power on.

When I connected the monitor to another computer, it showed a few lines on the screen when it was first switched on, and then a blank screen. I tried it with another computer - same result.

So it would appear that the PSU failure has caused a voltage spike on the computer's supply line(s) and this has damaged the monitor via the data cable.

Has anyone experienced this? If so, were you able to fix the monitor?

I have not tried to fault find yet, I want to await responses to this enquiry first.

Any advice will be appreciated.

 

[mvs sarma]

I have a CMV CT-712A, Model A170E1-OA flat screen monitor.

Recently, the power supply of the computer to which it was connected blew up. There was a bang & flash from its switching mode power supply unit (PSU) when I turned the mains power on.

When I connected the monitor to another computer, it showed a few lines on the screen when it was first switched on, and then a blank screen. I tried it with another computer - same result.

So it would appear that the PSU failure has caused a voltage spike on the computer's supply line(s) and this has damaged the monitor via the data cable.

Has anyone experienced this? If so, were you able to fix the monitor?

I have not tried to fault find yet, I want to await responses to this enquiry first.

Any advice will be appreciated.

The same spike or something would have also spoiled the Power supply of the Monitor. Please take the pain of checking the monitor too.

All the best.

 

[picasm]

LCD monitors often have a 3 year manufacturers warranty.
It may be worth checking if it is covered against any type of fault?

 

[ljcox]

Thanks for the replies.

Unfortunately, the 3 year warranty period terminated in Febuary this year.

Has anyone seen this happen to a monitor?

 

[mneary]

I have seen this happen to small power supplies.

Have you checked the monitor's power supply? It would not be unusual for it to fail at the same time as the computer.

And it would be highly unusual for the data lines to have a destructive signal.

 

[ljcox]

Have you checked the monitor's power supply? It would not be unusual for it to fail at the same time as the computer.

No, I have not done anything yet. I want to wait for comments from this thread first. I don't want to re-invent the wheel if someone else has had the experience.

Thanks for the comments.

 

[mneary]

Most smaller LCD monitors I've seen have a separate 12V power unit. If yours has one, it should be a simple matter to see if it produces 12V.

 

[ljcox]

Most smaller LCD monitors I've seen have a separate 12V power unit. If yours has one, it should be a simple matter to see if it produces 12V.

Thanks for the suggestion.

I measured the open circuit voltage. It is about 18.7 Volt. The label states the output is 19 Volt at 3.16 Amp.

So I'll make a dummy load tomorrow to see what it supplies at 3 Amp.

 

[mvs sarma]

Thanks for the suggestion.

I measured the open circuit voltage. It is about 18.7 Volt. The label states the output is 19 Volt at 3.16 Amp.

So I'll make a dummy load tomorrow to see what it supplies at 3 Amp.

please have a check whether the wires coming from the CPUs VGA socket are handled by another chip. this chip can also be suspected due to spike. I feel your LCD monitors PSU might be OK.

 

[ljcox]

please have a check whether the wires coming from the CPUs VGA socket are handled by another chip. this chip can also be suspected due to spike. I feel your LCD monitors PSU might be OK.

Thanks for the suggestion.

I assume that the "chip" that you mention is inside the Monitor, not in the computer.

Is this true?

 

[killivolt]

I think he's verifying? your first post. When it blew up sending a arrant spike to the chip.

 

[mvs sarma]

Thanks for the suggestion.

I assume that the "chip" that you mention is inside the Monitor, not in the computer.

Is this true?

Yes. The chip is expected inside the LCD monitor.
Otherwise a check of the monitor on another machine (laptop or CPU) would have proved it.

 

[ljcox]

Yes. The chip is expected inside the LCD monitor.
Otherwise a check of the monitor on another machine (laptop or CPU) would have proved it.

Thanks, that's what I thought you meant. But your reference to the CPU confused me.

18.7 Volt from the power supply seems a bit low given that it is with no laod and the label states 19 Volt at 3.16 Amp.

There must be a regulator inside it. I have not done the load test yet.

 

[mvs sarma]

Thanks, that's what I thought you meant. But your reference to the CPU confused me.

18.7 Volt from the power supply seems a bit low given that it is with no laod and the label states 19 Volt at 3.16 Amp.

There must be a regulator inside it. I have not done the load test yet.

Generally the SMPS as you know is kept at low Pulse width, and as the PSU is loaded the PW improves, thus compensating the drop on load and the voltage would come up to almost 19V. I feel a 0.3 V difference need not be bothered. Try connecting a 24V head lamp of a bike or two bulbs 6V and 12V in series and load it. 25 watt bulbs or 18W ones may be tried.

 

[Hero999]

A drop of 300mV at 3A doesn't sound so bad to me.

The wireing resistance might be as high as 100mhm: which would explain it.