Soniq lcd tv issues -.- (backlight)

[Noobomatic]

Okay so here for my second post ever haha, i have a soniq lcd tv which the backlight seems to half turn on then flik off every 0.8ish seconds. sometimes & i mean rarely itll light up fully and stay lit no problem so at first i thought ehh leaky capacitor or something had a look & couldnt see any visual signs & even checked the hv ceramic & they were fine,

i dont wanna go out and buy a new power unit for it since its only a 32 inch tv but maybe some knowledge would help i can post a pic of the board, im not sure what good it will do the model of the tv is a l32v12a-au there is absoloutely no visual signs i might check voltages in a min any thoughts? or some advice? i realy thought it would be the hv cap.

[tom66]

Re: Soniq lcd tv issues -.- (backlight)

Pictures of the boards inside and of each board would really help us understand how it is set up and suggest any tests.

[Noobomatic]

Re: Soniq lcd tv issues -.- (backlight)

theres some pics , hope they're good enough

[Noobomatic]

Re: Soniq lcd tv issues -.- (backlight)

okay so i tested the voltages they are all (roughly) about normal i tested with 2 multimeters for close enough accuracy and got

5vsb 5.2v
+5v & +5v 5.28v &5.27v

+12v & +12v both @ 12.52v.

+24v @ 24.9v


Just on another note sometimes the backlight does stay on and appears to sometimes flick on and off then as i just noticed it was doing it slower and slower then stayed on for a little bit

[Noobomatic]

Re: Soniq lcd tv issues -.- (backlight)

and now im ticked, its working one sound that interest's me is that the invverter makes a little pop sound if its not connected to the tube at all but if it has one or both connectors it makes no little crack/pop sound

[selldoor]

Re: Soniq lcd tv issues -.- (backlight)

Id guess running it without lamps isnt doing it any good. At startup its probably producing 2000vAC and until the protection kicks in that voltage has nowhere to go.
Are you saying otherwise it is now working ok? Maybe worthe checking the soldering on the inverter transformes and also on any high voltage Blue caps top right in your picture.
One Megmeet board used to burn away on a bad joint in that area then short out when the
board eventually trned to carbon.

[Noobomatic]

Re: Soniq lcd tv issues -.- (backlight)

well it seems as i let it cool down not that it got very warm i played a few games on it etc... its now showing signs of repeating the issue (backlight flickering) and being rather shifty ..i had a look at some of the solder joints and it seemed pretty clean maybe the inverter transformer is faulty? idk tbh

[Noobomatic]

Re: Soniq lcd tv issues -.- (backlight)

& ive also just seen on ebay that the upgraded mip329fl psu has doubble 6kv caps(on each pole as opposed to single on each pole) im just wondering if that could be the go (fix)

[selldoor]

Re: Soniq lcd tv issues -.- (backlight)

I dont know you could try it - When its flickering can you hear any noise like
crackling - electrical discharge- arcing - or smell ozone or burning
Try it in a dark room - I am thinking the solder on a bulb may be bad.
If it worked for a while its unlikely to be the transformers apart from bad solder
joints.
If you can get in to the bulbs you could examine the ends. Another idea would be to use a spare bulb or bulbs ( in an old monitor?) and sub them or construct a couple of "Test" Bulbs from cfls - Finda post by Budm - the instructions on how to make one are in his signature files.

[Noobomatic]

Re: Soniq lcd tv issues -.- (backlight)

when the tv is starting up do9ing the whole flicky game it doesnt realy make any audible noises that would say "hey im broken" unfortunatly.

i could re-solder all the high voltage shi* on the board and the connections to, i may even throw a 10pf cap on both ends of the tube links and see what good that does me im a little bit nervous about playing with teh ccfl's either in or out of the tv as i know they are realy fragile & there is no smells comming from the screen or the psu. i checked for sparks lastnight and nothing from anywhere on the board its trying to bug me i think, i also checked the voltage while the set is flickering and its staying at 24v & like many i dont have a 2-3kw multimeter so i dont dare test the voltage comming from the inverter.

[Noobomatic]

Re: Soniq lcd tv issues -.- (backlight)

so the tv is still doing the issue, i tried adding caps - changing the 6 kv caps with little to no difference but i did notice that when the right hand side of the board is earthed or grounded / whatever thats when the screen flicks on and off and if its not touching the meta then the screen stays on with no video displayed though its got me a little bewildered its rather confusing!

[hpelec]

Re: Soniq lcd tv issues -.- (backlight)

what is the state of the TV now. I presume u open the back cover. first see the backlight is steady from behind. it looks ur going in the wrong direction. this is not the power sup problem. this is something to do with firmware upgrade.

[Taterbug]

Re: Soniq lcd tv issues -.- (backlight)

I had a Vizio that was flickering and then the backlights would shut down and it was one of the tubes going bad that caused the problem. I had to tear the whole unit down to the backlights and replace the tube. That fixed the backlight problem. Be careful if you do this and dont crack the LCD screen. (I have actually cracked a screen before doing this).. But that did fix my backlight problem.