Technika 40-E271 TV with TP.MSD309.BP86 Mainboard

[johnedgley]

Hi all, this tv belongs to a friend and I repaired it (mainboard, badcaps) about 2 years ago (when it was just out of guarantee) and I also bought and repaired a spare mainboard. Help with that came from here!

A couple of days ago the screen went dead - completely black, no sign of backlight and seemingly no sound (though as it cannot be set to any specific source it's a little difficult to be sure of that).

The standby light comes on (red) ok and it "turns on" (i.e. goes blue) and off ok, however there are no flashing error codes and swapping to the other mainboard does not change anything. I have searched online fairly extensively and found plenty of mentions of this set (I know it's a Vestel cheapo) however the symptoms this time are different to anything I've found so far.

I have only a basic multimeter and similarly basic skills, however if anyone can suggest possible cause(s) or instruct me as to what to check I shall be most grateful!

[vinceroger69]

Re: Technika 40-E271 TV with TP.MSD309.BP86 Mainboard

can you upload a picture of the psu and mainboard this maybe a led issue so you may need to test the led voltages etc

[johnedgley]

Re: Technika 40-E271 TV with TP.MSD309.BP86 Mainboard

Photo attached, it's the best I can manage with my ageing phone - hope it's ok, if not I'll have to beg/borrow/steal a decent camera from someone (ok, not steal!)

[johnedgley]

Re: Technika 40-E271 TV with TP.MSD309.BP86 Mainboard

I found this pic which came with the spare board I ordered, and it's better than my own previous one, however I have just realised that I got my repairs confused (no surprise there) and I'm not sure I ever tested the spare so, though unlikely, it's just possible that they both have the same fault...

[ReeceyBurger123]

Re: Technika 40-E271 TV with TP.MSD309.BP86 Mainboard

LTA400HM23 panel-bad Leds in the screen open it up and replace them also bridge over Led string connections.

[dick_barton]

Re: Technika 40-E271 TV with TP.MSD309.BP86 Mainboard

Freeze UF11 and see if it comes on. You can use a can or air duster inverted or freezer spray.

If you have a DVD player connect it via the SCART input. Turn TV on, then the DVD player and the TV should switch over to the SCART so you can at least know if the sound/volume +/- is working.

[johnedgley]

Re: Technika 40-E271 TV with TP.MSD309.BP86 Mainboard

Many thanks for the replies;

@ reecyburger123 - thanks, I have now confirmed that it's the LED backlight (something I'm totally unfamiliar with coming from a laptop/invertor background) and will explore further as per your instruction. Could you possibly provide spec/source for the led's or link to any info?

@ dick barton - thanks also, however having confirmed backlights (and also since neither board works) I shall pursue the led's!

[vinceroger69]

Re: Technika 40-E271 TV with TP.MSD309.BP86 Mainboard

you really need to strip the panel down and see what led strip part numbers it uses theres some really good guides on youtube regarding lcd panel strip downs just be really carefull as the lcd panel can crack so easily and keep the diffuser sheets in the correct order once you find out what led strips these use it depends if your going to just repalce the bad ones or all in one go i have been using this ebay shop for leds recently
http://www.ebay.co.uk/sch/proman28/m...p2047675.l2562

[johnedgley]

Re: Technika 40-E271 TV with TP.MSD309.BP86 Mainboard

Now stripped (the tv thankfully - not me!) and even though there's nothing obvious I presume since no LED's light that the LED driver, SSL400_0D5A REV:1.0, is the culprit! Hence I'm now in pursuit of ideas/suggestions/test data for that (or maybe just source a replacement... rather not though!)

[dick_barton]

Re: Technika 40-E271 TV with TP.MSD309.BP86 Mainboard

Have you checked the fuse and the voltages on the connector 1 to 14

[johnedgley]

Re: Technika 40-E271 TV with TP.MSD309.BP86 Mainboard

No, but I will do now - thanks for heads up!

[johnedgley]

Re: Technika 40-E271 TV with TP.MSD309.BP86 Mainboard

Both side of the fuse show 23.9V, and the connector runs;
1 - 4 all 23.9V
5 no connection
6 - 11 all 0V
12 = 5.08V
13 = 4.95V
14 = 4.32V

I will search online for spec/more info as to what they should be, however if you already know/have an idea I'd appreciate it.

And thanks for al the help thus far...

[dick_barton]

Re: Technika 40-E271 TV with TP.MSD309.BP86 Mainboard

It says on the photo what the voltages should be and they look fine.

What voltage do you have at Vout as shown in post#9 photo 3

[vinceroger69]

Re: Technika 40-E271 TV with TP.MSD309.BP86 Mainboard

maybe whilst your waiting for answers start checking each led i use two aa batteries there are some good guides on you tube regarding test points on the strips

[johnedgley]

Re: Technika 40-E271 TV with TP.MSD309.BP86 Mainboard

@dick_barton; I saw that 1-4 were Vin, but couldn't figure what 12,13,14 (ENA, A_DIM & EXT_DIM) should be - that's what I was wanting to check.

Vout gives 22.9V, do you know what it should be?

It says on the photo what the voltages should be and they look fine.
What voltage do you have at Vout as shown in post#9 photo 3

@vinceroger69; will do!

[dick_barton]

Re: Technika 40-E271 TV with TP.MSD309.BP86 Mainboard

I found this but not a very good image.

They had a problem with Q005 being short circuit

[johnedgley]

Re: Technika 40-E271 TV with TP.MSD309.BP86 Mainboard

Found a thread here (https://www.badcaps.net/forum/showthread.php?t=41014, Sanyo, but same board) and there's a pic that seems to show Vout as 151V so there's def a problem with the driver - now about to work thro' the other points as best I can from that pic, which, though much better than nothing, is none too clear!

[johnedgley]

Re: Technika 40-E271 TV with TP.MSD309.BP86 Mainboard

I found this but not a very good image.

Lol - just found that and said the same thing! Thanks for persevering...

[johnedgley]

Re: Technika 40-E271 TV with TP.MSD309.BP86 Mainboard

Three photos here showing my values vs the reference ones on the (poor) photo - the ones with a "?" are very hard to discern on the original, in fact one seems to be missing altogether, but I've done my best, and if anyone can help pinpoint the likely cause(s) of the failure it'd be great.

Also, those ref values applied to the board when fitted to a completely different tv, i.e. powered from a different p.s.u., and I have no idea whether that would make a difference (or how much difference)

[dskall]

Re: Technika 40-E271 TV with TP.MSD309.BP86 Mainboard

Did you check screen with flashlight or torch as you on the other side of pond call it for an image on screen? Also did backlights flash on when first turned on?