Bush LCD27TV006HD 2 secs to black

[notallbad]

Re: Bush LCD27TV006HD 2 secs to black

Yes sorry, worked out based on 12v, getting confused with 12v bulbs and 24v rail.
So that would explain test lamps not coming on at start up.

[notallbad]

Re: Bush LCD27TV006HD 2 secs to black

To eliminate the ccfls and shorting to panel (wires, lamps) I have a spare panel but the connector to the bottom of the inverter board has two wires, black and white, whereas the original board only has one, black.
Any ideas how best to connect up?
Thanks

[notallbad]

Re: Bush LCD27TV006HD 2 secs to black

Stripped panel, removed broken lcd, found 16 lamps, 8 lamps connect to one pin and 8 connect to the other. No circuitry just a connecting pcb board.
So I can simply feed both wires into the one on the original inverter board to provide the return path.

[notallbad]

Re: Bush LCD27TV006HD 2 secs to black

The 2 pins on the inverter are actually connected together so won't need to short the 2 wires together, just 'plug n play'.

[notallbad]

Re: Bush LCD27TV006HD 2 secs to black

Does the same with spare panel lamps, half screen lit and flickers, admittedly these are 32" lamps driven from a 27" inverter. Same happens with just half the lamps connected.

I am steering back towards the PS, caps????, the 2 main 400v caps have 314v and 316v, a little low I believe.

[tom66]

Re: Bush LCD27TV006HD 2 secs to black

Is 24V from power supply OK?

[notallbad]

Re: Bush LCD27TV006HD 2 secs to black

Hi Tom
Apologies for delay, yes there is a steady 24v present, would the BlOn only having 4.1v have a bearing here or is that sufficient?
Thanks again

[tom66]

Re: Bush LCD27TV006HD 2 secs to black

Shouldn't be an issue, unlikely to be PSU.

[notallbad]

Re: Bush LCD27TV006HD 2 secs to black

I think the ccfl lamp test was sufficient to conclude they are fine and the fault resides on the inverter.
I have a couple of spare inverters so shall look at hooking them up to eliminate PS. Will need the PS wiring harness to the inverter to be re-wired.

[notallbad]

Re: Bush LCD27TV006HD 2 secs to black

Guessing I just need to provide 24v and the BlOn for the inverter to fire up?

[tom66]

Re: Bush LCD27TV006HD 2 secs to black

And DIM.

[notallbad]

Re: Bush LCD27TV006HD 2 secs to black

ok thanks.
Once I have without question determined that it is in fact the inverter, not that I doubt you just want to prove for myself and gain experience doing so, I shall get back to troubleshooting the 2 'faulty' inverters, odd that both are faulty with the same fault but then could be a common fault with these and intend on finding it and repair both these boards. I've already spent more than I had hoped on this, inverter and remote, caps and don't really want to spend much more if it can be helped but as I'm gaining experience that eases the pain a little.

If I haven't already noted just for reference, I have powered up the tv with the T-Con disconnected and although the screen does not light up, as to be expected, I can see the lamps flickering still. Just thought I'd throw that in for elimination.

[notallbad]

Re: Bush LCD27TV006HD 2 secs to black

What are VIPWM, VEPWM and VSel?
Which one is the Dim?

There is no voltage present on any of these at least not anything anywhere near even 1v.

[tom66]

Re: Bush LCD27TV006HD 2 secs to black

I honestly have no idea if it is an inverter or CCFL fault, if I knew I would tell you. Connect both VIPWM and VEPWM to 5V with 1kohm resistor in series.

[notallbad]

Re: Bush LCD27TV006HD 2 secs to black

Would that be on the inverter or PS side?

The PS b/d VE and VI PWM's appear to be connected to gnd, with the connector disconnected and DMM on 200ohm range get 0.4ohms(short test leads and get 0.4ohm) across VEPWM and gnd, VIPWM and gnd.

Just want to be sure what I'm doing here.

[notallbad]

Re: Bush LCD27TV006HD 2 secs to black

I now see where your going with this? The ve and vi are signals from the Main A/V b/d, and this will just bypass the PS b/d. I think!

Shall let you know how it goes.

[notallbad]

Re: Bush LCD27TV006HD 2 secs to black

So using a 1.2k ohm resistor from a 5v supply on the ps b/d then connecting the other end via 2 wires to ve and vi on the inverter b/d I still get the same fault. This gives 3.1v supply to ve and vi.

[notallbad]

Re: Bush LCD27TV006HD 2 secs to black

With a spare inverter b/d and a spare panel with 32" lamps I connected up 5 of the 24v, 5 of the gnd, BlOn and VIPWM and the panel lit up with no issues.

[notallbad]

Re: Bush LCD27TV006HD 2 secs to black

Next step I think is to hook up the spare inverter to drive the lamps on the tv in question and eliminate these for definate.

[notallbad]

Re: Bush LCD27TV006HD 2 secs to black

Incidentally this spare inverter also has an OZ960 so shall note some observations for comparison.

Unfortunately the spare inverter is for a 32" so will not physically fit the panel so shall either have to purchase another board or repair one of the faulty ones.