Technika M22/36B-GB-TCD1-UK

[Steve_Mc]

Hello everyone

I am trying to fix a Technika M22/36B-GB-TCD1-UK Unit switches on from standby via remote, CCFL's are lit. No OSD appear when menu button pressed. After a minute or so the picture begins to darken and what I see on the screen is similar to a color bar signal from a signal generator

Does anybody have any experience or knowledge of these Tesco cheap TV's?

Thank you,

Steve

 

[davenn]

Hi steve_Mc

welcome to the forums

I have moved your query to its own thread its always best to start your own thread.
You had originally attached it to a thread that was 2 years old

Havent seen that specific problem, tho it definately sounds heat related
I would be ...
1) having a look for any components that are getting really hot
2) checking all electrolytic capacitors ( the ones in aluminium cans) some may be bulging or have just dried out

A can of freezer spray is really useful at times like this for narrowing down a fault to an individual component or so

cheers
Dave

 

[Steve_Mc]

Technika

Thank you Dave

I have replaced all the electrolytics in the PSU and also used freezer on all the other PCB's....No joy!

I am looking on the internet but there is not much out there on this model

Regards,


Steve (ex Comet Service Tech)

 

[davenn]

would you like to take some pics of the PSU board ... component and copper sides
sharp and well lit

when you used the freezer spray did you use the small tube so you could direct the bursts of spray at specific components ?
Did you actually wait till the fault showed itself BEFORE spraying ?

Dave

 

[Steve_Mc]

Hi Dave,
Yes I did use the straw to direct the freezer and waited till the fault was present.
After further investigation and tapping boards the Inverter board is very "Microphonic"
I believe the inverter PCB even though the lamps are lit is the cause of the fault. It is failing under load.
I am a TV Engineer....just have no data on this model. I will replace/repair the inverter and post back in a few days if all is OK ;-)

Many Thanks for your kind assistance.....Steve.

 

[davenn]

no probs.... I have to ask the questions
its rare that we really know what abilities a person has .... many are trying difficult repairs or project building with no experience at all lol

Dave

 

[Steve_Mc]

Thanks very much Dave

The cause of the fault is a failing Inverter PCB. Part: LK-IN220406A

The symptoms were:

At switch on the screen would illuminate, 30 seconds later would start to dim and produce what looked like a color bar display from a signal generator! There was a slight hum through the speakers and the DVD mechanism was whirring. You could still switch on and off via remote but no OSD was present. (Only the colored bars)

Seems like I have caught it during it's dying time Most failed inverters just give no rear lighting but you can shine a torch into the screen and see the video. Sound is sometimes present.
It was like when I worked for Comet we got a lot of Chinese TV's (Onwa) with weird faults...very time consuming. Once found though all was happy

Thanks Dave

 

[davenn]

Thanks for coming back with a resolution, some one else may find it useful one day

cheers
Dave

 

[Steve_Mc]

No prob's Dave

If the Manufacturers provided some info on all the cheap Tat they make we would not all be looking for solutions

It is hard to test these units. Once you open the front you have to remove the inverter leads just to get inside to have a look. Then you cannot do any measurements under "Load".

My guess is at switch on all is OK for 20- 30 secs then the inverter board breaks down and overloads the PSU. Then the PSU voltage rails fall to a level were the cannot operate the other boards properly due to the strain on the PSU by the inverter

Thanks for trying to help mate

Kind regards,

Steve.