no image (backlight?) on Xenarc 700TSV

greenman100 · 04-08-2005, 09:11 PM

Hey,

I recently purchased a Xenarc 700TSV off someone here on the forums. when I recieved it, the image on the screen blinked a lot. Now, it won't turn on at all. It seems as though the backlight isn't working, maybe the inverter is broken? Is there any way for me to know for sure or fix it?

Any help would be greatly appreciated.

Thanks.

DaRacerz · 04-08-2005, 11:16 PM

well, the flickering was definitely a bad sign. Now, when you attempt to turn on the display, does the green light in the middle ever turn on? Also, take a good look, cause if the backlight circuit has went, you still should be able to dimly see an image on the screen when the lighting conditions are good.

Scouse Monkey · 04-08-2005, 11:21 PM

if you do find it is the backlight then thereis a small pico fuse on the inverter circuit board. (yay 4444th post!)

EDIT:and looking at the Xenarc i have n my desk in bits right now it is a 1.5A pico fuse and is mounted next to the 4 wire connector from the main controller board.

greenman100 · 04-08-2005, 11:28 PM

Quote: Originally Posted by DaRacerz

well, the flickering was definitely a bad sign. Now, when you attempt to turn on the display, does the green light in the middle ever turn on? Also, take a good look, cause if the backlight circuit has went, you still should be able to dimly see an image on the screen when the lighting conditions are good.

yup, turns on and stays on for about 15 seconds, then starts blinking like it's in auto-off mode (no inputs are connected)

EDIT: fuse measures at .2 ohms while in-circuit. I assume that is ok

greenman100 · 04-09-2005, 10:56 PM

ideas?

greenman100 · 04-10-2005, 05:55 PM

Quote: Originally Posted by joshthepilot

Loose wire from your inverter? Maybe the 2 that go into the lcd panel backlight. Maybe one of the 4. If you have a voltmeter, test the 4 wires and make sure you get 12V on one line, 0V on another line which should have zero resistance between any other ground in that unit, and the other 2 should read either 5V or 3.3V. Or, if that large dark rectangular item(actual inverter) gets warm on the top, it is working. If you only touch the top of it, you will not burn yourself.

I get 12v on one, and 0 on the other 3. It's like hte other 3 are connected to ground.

I checked the output of the inverter and it was reading 0v on my cheap meter that goes up to 500v. I'm pretty sure it's the inverter, or maybe the inverter needs those other power supply rails. Anyone have ideas?

greenman100 · 04-10-2005, 11:22 PM

Quote: Originally Posted by joshthepilot

Yea, the inverter needs 5V(or 3V) on 2 of those lines to function. So if it is not there, it is on the main controller that is the problem. Start tracing the wires and board traces to something that is broken.

oh boy. great.

greenman100 · 04-11-2005, 09:21 AM

Quote: Originally Posted by joshthepilot

Oh but you know what else, those 2 lines that should be 5(or 3) Volts, will not be 5 volts when the xenarc wants to turn off the inverter. Those getting the power is how the xenarc controls the inverters output. So maybe when you were checking voltages, the xenarc went in a power save mode?

excellent point, I'll have a look at that today.

greenman100 · 04-12-2005, 09:30 PM

ok, one line checks out at 12v, another at 3ish volts, and the other 2 are at 0 volts

greenman100 · 04-21-2005, 05:00 PM

and even when the inverter is not in power save mode, the output of the inverter measures at 1.1VAC.

Scouse Monkey · 04-21-2005, 05:06 PM

you measured the output? be careful that thing puts out 600V!

The inverter could be controlled via PWM or could be a voltage system.

if it is the voltage system there could be one input that changes from 5V to near 0 volts when the inverter is made brighter (5v = full dim). There could also be another wire to initiate the inverter and the ramaining two are for power. It could be 5V but i suspec tthey are using a 12V inverter.

You should be able to pick up an inverter pretty cheap if it is that. Thay have been known to go.

Gobby · 04-21-2005, 05:12 PM

Yeah and it hurts if you accidentally touch it **Whistles**

greenman100 · 04-21-2005, 05:13 PM

Quote: Originally Posted by Scouse Monkey

you measured the output? be careful that thing puts out 600V!

The inverter could be controlled via PWM or could be a voltage system.

if it is the voltage system there could be one input that changes from 5V to near 0 volts when the inverter is made brighter (5v = full dim). There could also be another wire to initiate the inverter and the ramaining two are for power. It could be 5V but i suspec tthey are using a 12V inverter.

You should be able to pick up an inverter pretty cheap if it is that. Thay have been known to go.

I'm careful, I'm using a Fluke 179, it's rated up to 1000volts, and I'm taking all precautions.

Also, the unit is able to sense me plugging in a source - that is, I power it up, and after ~10 seconds the LED starts blinking. Then, after I plug in the VGA cable, the LED comes on and stays on.

Any idea where I can get an inverter?

Scouse Monkey · 04-21-2005, 05:20 PM

Xenarc or digitalww

if you press the menu button can you see anything on the screen?

Scouse Monkey · 04-21-2005, 05:21 PM

oh and one more thing, you fluke may be rated upt o 1000V but did you know that to start a CCFL the inveter kicks out a high voltage? For the Xenarc 600V tube this could be close to or more than 1000V! It does this until the CCFL fires and the impedance changes (or summit like that) then it drops down to 600V and keeps a constant current at about 5mA.