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Iiyama monitor PL2483H - No LED Backlight.

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Turnip:
Hi Folks,

Have this one in where initial OSG is visible with a torch. Set doesn't cut to S/by, but no other display as didn't bother try any input.

Checked usual diodes and caps finding no problem, suspect screen LEDs.

With a CCFL monitor it's a doddle to check tubes, but this one has a plug with 6 wires the screen, whereas most have just a couple.

Checked around, and no info about LED failure on this monitor, or anything else.

Wonder if anyone has sorted this problem - Thanks - Chris.

Davy:
Hi Turnip

I'd be treating it like LCD telly inverter or no supply to inverter the leddy's..... the LEDs are usually ran in banks and driven from a inverter.... that *may* be hidden under the screen where the CCFL's are usually parked.

I'll stick mi neck out and bet they won't ALL be ran together Chrimbo tree style or paralleled. I have a IIyama CRT monitor.... that keeps working working and working, usually highly rated IIyama are.

The LED's could give trouble..... I doubt this is the fault though, unusual for them all to be out I'd say.

Dave

downunder:
Hi Chris,

Some activity on quuq at last! I thought it might have slid into an abyss.

As Dave points out, the panel LEDs are arranged in strings, irrespective of whether they're mounted top and bottom, left and right sides, or in an array (scattered throughout the back). The last is probably the easiest to fix, but the arrangement of the LEDs is a Midsummer Murder mystery until you crack open the panel to access the LED cavity, something I relish doing just for the Halibut.

Sounds like your LED Driver is part of your PSU and 6 wires into the panel means 3 voltages in to the LED strips and 3 return wires where failure detection is normally facilitated. Failure of just one LED, because they're in series, will cause the micro to shut down all LEDs. On said plug, the LED Driver should generate 3 voltages, not necessarily the same, but of the order of 75V to 150V, depending on # of LEDs per string.

With the panel apart, you can spot any burnt out or heat-stressed LED or joins, and you can isolate each string, and using a current-limited variable bench power supply, you can see if each string lights up. Start with low volts and wind it up slowly until the LEDs ignite with low illumination. Don't copy my first effort and start on "surmised voltage", destroying a LED string.

Bruce Chapter XXII, Verse XLIV

Turnip:
Thanks, Davy and Bruce,

My first LED back-light failure so naturally reluctant to come to a premature conclusion.

Otherwise - Simply ignorance. Suspected however that any functioning string would give a brief flash B4 set cut to S/by, but with this one - Nothing at all.

Hi Bruce, will wind them up slowly, but they're just top and bottom jobbies, as most small monitors are.

Enjoyed Chapter and Verse, as guess Quuq folks will - Love your Latin, but a bit dubious, as suspect It's Australia, where folks only came together recently - Chris

downunder:
Hi Chris,

Strangely nuff, LED backlight don't seem to give the momentary flash that CCFLs do. Top and bottom jobbies......these can be dicey as the individual LED terminals can be impossible to get at, but if you do succeed in getting access to a crook LED, you can bodge it by substituting a reverse biased 3.6V zener.

Bon chance, and don't knock the Latin.....I studied it at school, and a fat lot of good it did me....don't think they use it any more.

Bruce

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