technika 22" quick question

[shepp]

tv powers up but then back light drops out, ive replaced invertor with no joy.......should of traced fault first but was being lazy.....

on the main board if there is no 3.3 V at the test point does this mean the main is faulty....given that im getting 12V stable and 5V for BLO

and one other thing....should i get a voltage for ADJ? to the invertor

[tom66]

Re: technika 22" quick question

I dealt with basically the same TV, except mine was a Grundig and used an external 12V power brick. Mine had a 3.3V regulator where there is an empty pad, and didn't use that jumper.

The fault I reckon will be CCFL or PSU.

[ben7]

Re: technika 22" quick question

tv powers up but then back light drops out, ive replaced invertor with no joy.......should of traced fault first but was being lazy.....

on the main board if there is no 3.3 V at the test point does this mean the main is faulty....given that im getting 12V stable and 5V for BLO

and one other thing....should i get a voltage for ADJ? to the invertor

Maybe the 3.3v voltage regulator is bad.

[shepp]

Re: technika 22" quick question

PSU is fine, and back light is working when it comes on,

BLO is getting 4.7V, is it supposed to get a reading on the ADJ?

and before the backlight switches off the screen gets a few small fuzzy lines on it then goes off, its got to be either the tcon or main, but i want to rule out the main before i strip it down any more

[tom66]

Re: technika 22" quick question

You have a scope?

[shepp]

Re: technika 22" quick question

Maybe the 3.3v voltage regulator is bad.

on the main board? and what is the 3.3v for?

[shepp]

Re: technika 22" quick question

You have a scope?

no, just a meter

[tom66]

Re: technika 22" quick question

On mine, the 3.3V regulator was oscillating badly, partially causing video noise... Could be the problem but you'd need a scope to check.

[shepp]

Re: technika 22" quick question

On mine, the 3.3V regulator was oscillating badly, partially causing video noise... Could be the problem but you'd need a scope to check.

but im not getting 3.3V? so surely this is the fault? (i havent managed to test it when the screen is working because it wont come on now, but the green light comes on)

and 12v and 5v are still present and stable

[tom66]

Re: technika 22" quick question

There are several 3.3V regulators, and I believe that's an option jumper to select which voltage the T-con sees or something similar.

[shepp]

Re: technika 22" quick question

There are several 3.3V regulators, and I believe that's an option jumper to select which voltage the T-con sees or something similar.

i get you, so looks like ill have to check tcon board then to see if im getting 5V to the regulator thats on the tcon board?

or is there any thing else on the main board i can check first?

[tom66]

Re: technika 22" quick question

Just check the voltage going to the T-con you should see a test point near the power connector or if you need to check it on the T-con. I don't think it would power on at all without a voltage. How sure are you the new inverter is still good?

[shepp]

Re: technika 22" quick question

Just check the voltage going to the T-con you should see a test point near the power connector or if you need to check it on the T-con. I don't think it would power on at all without a voltage. How sure are you the new inverter is still good?

not 100% but ive fitted 2 other ones now and its still doing the same fault, so i couldnt imagine 3 invertors all being faulty with the same fault

how does the back light work? does it switch on with BLO or ADJ? because if its BLO then the backlight should be on as its getting 5V to it, so maybe its a faulty CCFL, but then again.....how would that effect the screen picture, it shouldnt....unless its something to do with the ADJ (im guessing this is for control of the brightness) as im not getting anything from this, so would that cause the backlight not to be on?

[tom66]

Re: technika 22" quick question

ADJ should be a voltage from non-zero to about 3V it controls brightness of the screen.

[shepp]

Re: technika 22" quick question

ADJ should be a voltage from non-zero to about 3V it controls brightness of the screen.

all im getting from that is mV, but even when it comes on it was reading about 60mV, when it didnt work it was on about 40mV, i tried turning brightness up as well when it come on but it didnt seem to effect the reading but the brightness still changed...thats what puzzled me

i tried negative prob on common from psu, then tried reading it from screw on main board and it was the same reading

[tom66]

Re: technika 22" quick question

Might be a PWM signal then so difficult to measure with meter.

[shepp]

Re: technika 22" quick question

Might be a PWM signal then so difficult to measure with meter.

could this signal effect wether the backlight comes on or not?

ive just checked screen with a torch and its definatley just the back light, the tcon must be good cause i can still see the picture

[ben7]

Re: technika 22" quick question

Did you get the right inverter?

Take a look at the ccfl bulbs, if they have black marks at the ends, they are burnt out. Also check the cables for arcing.

-Ben

[shepp]

Re: technika 22" quick question

Did you get the right inverter?

Take a look at the ccfl bulbs, if they have black marks at the ends, they are burnt out. Also check the cables for arcing.

-Ben

havent gone that deep yet, just waiting on my mate getting back to me, see what he wants to do

will i be able to get the bulb from the uk though? just done a search and there £30-40 from US, so its not gonna be worth doing

[shepp]

Re: technika 22" quick question

found what the problem was...... one of the wires that went into the rubber of the bulbs was burnt off, unfortunatley these looked like they were built to the panel so ive bin'd the screen and casing and kept the boards


lesson learned