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Sceptre x9 Komodo will not turn on. No light, power cable is good. Took apart, fuse is good - Power supply or logice board? How much for each? Thanks Jim

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I repaired one by replacing C107, 22uF electrolytic cap in the power supply.
Monitor Mike

Posted on Nov 28, 2008

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My Dell Dimension 2350 won't power on. I've checked cables, power strip, reconnected cable to a known working outlet, and looked under the hood for a breaker. Any other suggestions?


There are four diagnostic lights on the back of the unit. This linke will provide you with what they mean. http://support.dell.com/support/edocs/SYSTEMS/dim2350/advanced.htm#1218079

If all four lights are off, your power supply has most likely died (or the internal fuse is blown). It depends on how far into the computer you are willing to dive. To check the fuse, you'll need to remove the power supply and then remove the cover from the power supply. The fuse will be on the main PCB board inside the power supply. If the fuse is blown, try replacing it (it may blow again). If it blows again after replacing, then the power supply will need replacement. If the fuse is not blown, the power supply is still the likely problem and will need replacement. Be advised that Dell power supplies are special made for Dell cases, so you'll need to be sure that the replacement you get is for your computer or you will have to do some case modifications to get it to fit.

Dec 21, 2010 | Dell PC Desktops

Tip

Basic LCD Monitors troubleshooting guides


By Bud Martin
First if you can, try the monitor with other PC first to make sure it is not the PC problem.
Notes: We are dealing with high voltage that can kill you! so if you are not sure what you are doing, please have it fixed by the pro that has proper tools and safety equipment. Try to use GFI outlet and isolation transformer when work around the TV set and DO NOT DEFEAT THE GROUND PIN OF THE OUTLET/POWER CORD.

The monitor will have at least 2 circuits boards, one board will be the logic board where the video cable from PC is attached to, the second board used in most monitors today is the Power supply/backlight inverter board combinations. Some monitors will have separate power supply module and backlight inverter board.
The monitor should be connected to the running PC otherwise it will go into standby mode.
The operations of each board:

1) The Power supply board:
It takes the 120vac 60Hz and converts it to high voltage DC (around 160~170vdc filtered by the 80~150uf 250~450vdc cap) by the bridge rectifiers to be used by the switching power supply circuits that converts this DC voltage into high frequency (around 50~100 KHz) AC for driving the step down transformer. The outputs (usually 2 outputs) of the transformer will be rectified by the diodes to produce the regulated 5vdc for the logic board, and regulated 12~20vdc (12vdc is usually for screen up to 17inch, 16~24vdc for 18~24 inch screen).

The power supply circuits are always on (unless the monitor uses the power switch that actually disconnects the power from the outlet which is rarely used these days) which means that it is running 24/7 using the monitor or not, any spikes and surge will be fed into the monitor power supply.

Common problems:
Blown fuses, bad caps (leaking/bulging tops or bottom seals, please note that bad cap may look normal but it can have high ESR (Equivalent Series Resistance). The DC filter cap should be low ESR type for using in the switching power supply; general purpose electrolytic types will not last very long in switching power supply circuits. Poor solder joints, over heated components.

Testing:
Plug the monitor in but do not activate the power switch so the backlight inverter circuits will be off. Check the 5vdc and the 12~24vdc to make sure they are OK. They should be tested with the load, you can use 6V 1A (6watts) lamp for the 5vdc, and car lamps such as 1157 (12v 8watts lo/26watts high) turn signal brake lamp using high filament connection for testing the 12~18vdc (or use two 1157 in series for 19~24vdc) for the backlight inverter circuits.
If the power supplies are working, the output voltages should be steady at the rated voltages. The power supply will go into shut down if it detects too much current draw due to false in the power supply or short circuits in the backlight inverter or in the logic board.

2) The backlight inverter circuits:
It takes the 12~24vdc and converts it to high frequency AC to drive the inverter transformers CCFL (Cold Cathode Fluorescent Lamp) assemblies. The transformers will drive the CCFL by applying the start up voltage (around 1500~2000v), when the CCFL start conducting, the voltage will drop down to about 500~800v.
The inverter has detection circuits to detect open circuit if the lamp is not attached or does not fire up after the start up voltage is applied, it will go into shut down. It will also shut down if the lamps draw too much current due to ages (when lamp gets old it will draw more current).
The inverter gets two signals from the logic board, one is the backlight ON/OFF signal, the other one is the Dimming signal for the lamps.
Common problems:
Bad filter caps, resonant caps (in the inverter output circuits), blown transistors/IC, shorted or open transformer winding.
Testing:
You should have spare lamps for testing the inverter circuits.

3) Logic board:
The logic board get the signals from the VGA (ANALOG) or DVI (DIGITAL) and processes them and feed them to the LCD panel T-CON (Timing Controller) board on the back of the LCD panel.
It also sends out two signals (backlight ON/OFF and Dimming) to the inverter circuits when the monitor is on and getting the signals from the PC.
If the logic board does not get the signal from the PC, it will put monitor into standby mode.
The 5vdc feeding it is converted to 3.3v, 1.8vdc by the switching buck converters to run the processor.
The logic board also sends the 5vd or 12vdc power for the T-CON board, if the voltage is not there, you will see white/grey glowing screen only.
Not much repair you can do on the logic board unless you have the full service manual and surface mount repair station.

4) CCFL and Inverter circuits testing:
If you don not have the inverter and lamp tester boxes you may be able to do a simple test by using these steps:
If the screen flashes on for a second, you can disconnect all the lamp connectors and connect it into one of the transformer output connector and see if you will see the flash on the screen, if you do, then try it with another transformer output connector to see if it also get the flash on the screen.
Repeat the procedure with other 3 lamps. If all the lamps do flash on for seconds then more likely the lamps are OK. If lamp only flash on one of the transformer output then you will know that the problem in that transformer inverter circuits.
If none of the lamps flash at all then the problem is in the inverter circuits, power supply, or not getting the on signal from the logic board.

Bad caps
http://i.fixya.nethttp://i.fixya.nete17e9cc.jpg

Power supply/inverter board (L), Logic bd. (R)
http://i.fixya.nethttp://i.fixya.netbc19983.jpg'

Dead T-CON bd, blown fuse. Get glowing screen only.
http://i.fixya.nethttp://i.fixya.net4fbd9e1.jpg

T-CON board's fuse F101
http://i.fixya.nethttp://i.fixya.net8506e44.jpg

Inverter board surface mounted fuses, F1 and F2

http://i.fixya.nethttp://i.fixya.net1bf6596.jpg
Bad lamps (Blackened ends, burnt /poor soldering)

http://i.fixya.nethttp://i.fixya.net5c8952e.jpg

http://i.fixya.nethttp://i.fixya.net4e5e9a1.jpg

Bad LCD panel (solid vertical lines)

http://i.fixya.nethttp://i.fixya.netffe90fe.jpg

Bad LCD panel due to bad T-CON board
http://i.fixya.nethttp://i.fixya.netef48b18.jpg
Failed TV and Monitors:
http://s807.photobucket.com/albums/yy352/budm
http://en.wikipedia.org/wiki/Capacitor_plague
Make your own test lamps: http://www.badcaps.net/forum/showthread.php?t=19987

on Sep 25, 2010 | PC Desktops

1 Answer

My Dell Inspiron 530 wont turn on


yes buy a power supply. I have seen hundreds of computers that have gone through storms. Remember a Dell usually uses a special power supply.
For a good deal look on ebay for your specific model, They almost always have "Buy it Now" deals.

Aug 15, 2009 | Dell Inspiron 530 Desktop Computer

5 Answers

POWER SURGE ZAPPED COMPUTER.WILL NOT POWER UP..WHER IS THE FUSE


the only fuse is in the power supply, if its totaly dead i would replace the power supply module. if that doesn't fix it the main board would also be bad

Jul 21, 2009 | E-Machines eMachines Desktop PC

1 Answer

Monitor goes black but the green light stays on. I turn the power button off and then back on and it comes back on. It may stay on for a few seconds to several minutes.


Check to see if the image is Dimmed. Chances are the power supply on the FPD is either dead or not supplying power to the back lights.

Your problem is the back lights are not being powered. There is a signal going to your FPD because the power light remains on green, but the back lights are what helps support an image from the Front Panel Display.
The only way to fix this is to open it up.

If its got 3 boards inside((logic-->video, Inverter, Power)) The problem is the Inverter. Replace it.
The inverter is the board that supplies power for the backlights to turn on. The backlights
provide a light.for the LCD Panel(provides color and is the logic. ... similar to a projector.
If its got 2 boards inside ((Logic-->video, Power)) The problem is the power supply. The inverter is embedded onto it.

Simply replace the part with a known good one, and you got a spanking new monitor.

Sep 18, 2008 | PC Desktops

3 Answers

Emachine desktop pc will not power up


flicknasty, take cover off and check with small light and look at all the caps (capacitors) to see if any are raised. Look like mini barrels. All it takes is one to shut your machine down and keep it down. If you find one or more, the logic board is no good. Also check fuse where power connection is on the logic board. Make sure you are not plugged into machine with AC before testing with meter.

Apr 28, 2008 | E-Machines eMachines Desktop PC

1 Answer

Emachine power supply


Unfortunately, E-Machines are well known for their power supply problems. I have a room full of them.

Let me guess, you can hear something rattling around in the power supply, right?

When this happens, a component blows cleanly off of the board inside, and sends a voltage spike to the mainboard.

With any luck, the hard drive logic board wasn't damage, and you can recover your data with another PC.

Apr 25, 2008 | E-Machines eMachines Desktop PC

1 Answer

I HAVE RELISYS TL766 MONITOR AND IT HAS GONE COMPLETLY DEAD, NO LIGHT SHOWING ON FRONT OF MONITOR, COULD YOU TELL ME IF THERE IS A FUSE INSIDE MONITOR, WHICH COULD HAVE FUSED, WOULS APPRECIATE ANY...


Generally inside there is a fuse on the power board. This fuse is soldered in on the board. Before taking this apart and testing the fuse or replacing power board or inverter, test the power supply to make sure it is producing the correct voltage and amperage.

If the fields of the "Brick" are breaking down this could also prevent the unit from operating.

Apr 18, 2008 | PC Desktops

2 Answers

Fuse


Are there any fans moving in the case? As in, are you getting any power? If no fans are moving, it's possible it's:
1) the power supply (PSU)
2) your 'jumper' from the power button to the motherboard has come unplugged
3) you're grounding out somewhere

One cheap-o way of testing a power supply is:

Turn your power supply off.
Unplug your power supply.
Get a paper clip.
Bend it into a U-shape with the ends close together.
Put one end of the paper clip into *the* green wire in the plug of the PSU.
Put the other end of the paper clip into a black wire of the PSU.
Plug in the PSU.
Turn on the PSU.
If the fan runs in the PSU, it's safe to say this PSU is in working order.

If the the power supply was fine, but when you hit the power button and it no fans inside the case move, check the plug from the case to ther "power on" jumper on the motherboard. if that's correct, I'd suggest removing the entire motherboard from the case and setting it onto a phonebook and see if it'll turn on there.


If fans are moving when you hit the power button, but no beeps, fans turn back off after a moment, ect:
1) Motheboard is bad
or
2) Processor is bad

These are the situations that are most likely.

Computers are picky about being played around in. You can look at them wrong and they'll stop working. Sometimes it's as simple as pulling them apart and putting back together again to make them work... at least in my experience. I wish you the best of luck.

Nov 16, 2007 | HP Pavilion a420n PC Desktop

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