Bush LCD27TV006HD 2 secs to black

[notallbad]

PS b/d: 04TA069I (Profilo Telra)
Main b/d: 04TA097D
Inverter b/d: Darfon V070 4H.V0708.001 / E5

When powered up from standby the standby light flashes steady 3 times, the screen lights up briefly then goes blank, the standby led then flashes once.
Tv stays on and get audio and tv reacts to keypad panel, i.e volume up/down, change select different source inputs

Confirmed that the backlights come on and then go off, so the backlights are definately off but 24v rails still present and so is 5v but not sure if this is BLon or PWM.

There is no visible picture when shining a torch at the screen though believe an image may not always be seen depending on panel, its a CMO.

On the Main b/d there is the 5v stby and 5v main when powered on and around 5v on V-TVT whatever that is, but no 12v on pin1.

I believe the fault is on the PS b/d not providing 12v to the main b/d but the key to solving it is the error blinks, what do they mean?

Any ideas please

[tom66]

Re: Bush LCD27TV006HD 2 secs to black

Pictures of any of the boards??

[notallbad]

Re: Bush LCD27TV006HD 2 secs to black

Yes, sorry. It was getting late and just had to get some shut eye.

Photos of PS b/d and inverter connectors

There is about 4.1v on the inverter pin on/off, 24v on all Vin's but nothing on VSel, VEPWM, VIPWM.

On the PS b/d there were some swollen caps so these have been replaced purely because they looked due to pop. 3 x 2200uF 25V and 1 x 16v and 4 x 1000uF 25v.

[tom66]

Re: Bush LCD27TV006HD 2 secs to black

Are those "SD" caps used as replacements?

[notallbad]

Re: Bush LCD27TV006HD 2 secs to black

Erm, yes. Am I due a telling off?

2200uF are SD
1000uF are Suntan

[tom66]

Re: Bush LCD27TV006HD 2 secs to black

Yes. Rapid Electronics or eBay? They are not good caps. Completely unsuitable for SMPS... Example
https://www.badcaps.net/forum/showthread.php?t=30085

Panasonic FC, FM, FR are suitable and readily available on eBay and Farnell.

[notallbad]

Re: Bush LCD27TV006HD 2 secs to black

OK, so I can't even use the excuse of just using them 'temporarily', so hands up!
I'm a naughty boy!!!

Shall order more of those good caps that I have run out of.

[notallbad]

Re: Bush LCD27TV006HD 2 secs to black

I can now confirm that there is in fact an image on the screen, these CMO panels are very hard to see without backlights.

So on the basis that all other functions appear to be working I think its most likely a faulty inverter board, of course tubes can't be ruled out just yet!

[tom66]

Re: Bush LCD27TV006HD 2 secs to black

That would seem right but do replace the caps first!

[notallbad]

Re: Bush LCD27TV006HD 2 secs to black

Most certainly, thanks Tom

[notallbad]

Re: Bush LCD27TV006HD 2 secs to black

Looking at the inverter the 4 fuses appear to be good.
Need to check those trannys 4006A546 .140 for shorts.

Question, I have some other 4006A trannys (4006A419105), are they universal?

[tom66]

Re: Bush LCD27TV006HD 2 secs to black

Or opens.

[notallbad]

Re: Bush LCD27TV006HD 2 secs to black

I guess remove each in turn and test.

8 pins - 4 primary and 4 secondary

((((Primary, 2 middle should be common (aha, only common whilst in-circuit)
Secondary, 2 middle should be common (aha, only common whilst in-circuit)))))) IGNORE!!!

(((((So to test do I check with DMM (ohm setting) across each sec winding (pins 5 and 8) and then to middle common pins (5 to 6/7 and 8 to 6/7) and the same on the pri (pins 1 and 4) (1 to 2/3 and 4 to 2/3)?))))))) IGNORE!!!

To test DMM across each winding ( 4 windings per tranny), i.e. opposite pins in this case.



Looking for 950 ohm and 1.4 ohm perhaps? Or there abouts.

Hope that makes sense.

[tom66]

Re: Bush LCD27TV006HD 2 secs to black

They can be in circuit.
You want to just match them.

[notallbad]

Re: Bush LCD27TV006HD 2 secs to black

On the 4006A419105 trannys that I already have there appear to be 4 windings
All read about the following which is whats to be expected, around 950 ohm and 1.4 ohm:
Pin 1 to 8 - 962 ohm
Pin 2 to 7 - 1.3 ohm
Pin 3 to 6 - 1.3 ohm
Pin 4 to 5 - 969 ohm

Shall cross compare against the trannys from the board.

[notallbad]

Re: Bush LCD27TV006HD 2 secs to black

Looks like the 4006A546. 140 have the following readings:

Pin 1 to 8 - 954, 960, 955, 972, 964, 968, 958 ohm
Pin 2 to 7 - 1.4, 1.4, 1.4, 1.4, 1.4, 1.4, 1.4 ohm
Pin 3 to 6 - 1.4, 1.4, 1.4, 1.4, 1.4, 1.4, 1.4 ohm
Pin 4 to 5 - 956, 963, 958, 975, 967, 964, 958 ohm

The fourth, fifth and sixth ones look a little high.

Any thoughts?

[tom66]

Re: Bush LCD27TV006HD 2 secs to black

None look particularly bad, typically when they go wrong you get 2~5x reading.

[notallbad]

Re: Bush LCD27TV006HD 2 secs to black

Erm, what else can I check?

[tom66]

Re: Bush LCD27TV006HD 2 secs to black

Could be a bad bulb. Post a picture of the inverter and it may be possible to disable error detect so you don't have to take panel to pieces.

[notallbad]

Re: Bush LCD27TV006HD 2 secs to black

Inverter b/d

OZ960GN CCFL Inverter Controller