Bang&Olufsen 6-26 with strange picture

[olegeisler]

Trying to fix this TV for a friend. It is a small LCD, made by Bang&Olufsen, I think the best term is that it is a designer-TV. It was VERY expensive, and the owner really want to have it fixed. Only official way to get parts, is through an authorized B&O dealership, and it is simply chassis or LCD panel exchange. The cost is beyond belief.

The problem can be seen on picture 2, the picture is "triplicated". It is not always, it happens during startup. If the set starts, it runs - no problem. If it has the "triplicated" picture, it can be remedied by 1 or 2 re-starts.

Now, I have the opportunity to purchase parts from a set, but the seller knows he can charge a good price - well, that is OK. But which board to go for ?
The T-con in the top ( pic 5 ) , or the "video controller" ( pic 4 ) - or could it be the panel ?

The T-con has two flat cables going to the panel, I can dig in to them if necessary, but it will take a lot of disassembly

Any ideas out there ?

[CapLeaker]

Re: Bang&Olufsen 6-26 with strange picture

Clean all the ribbon cables / connectors going from the main to Tcon and from Tcon to panel.

[olegeisler]

Re: Bang&Olufsen 6-26 with strange picture

Clean all the ribbon cables / connectors going from the main to Tcon and from Tcon to panel.

Thanks for the suggestion. Removed all connectors / both ribbon cables - cleaned the ribbon cables with cotton swab wetted with "Kontakt 60" contact cleaner. The others just sprayed with "KONTAKT 60" - then re-seated several times.

At the fifth startup, triplicated picture again

But, now I tried. Any other suggestions ?

The panel is now accessible, so I can do all kind of testing.

[ReeceyBurger123]

Re: Bang&Olufsen 6-26 with strange picture

What panel does it use ? Looks like tab bond issue to me.

[olegeisler]

Re: Bang&Olufsen 6-26 with strange picture

What panel does it use ? Looks like tab bond issue to me.

OK, thanks - Can that create such a picture ?

See attachment for type. Says SHARP LQ255T3LY44

Can probably buy a panel with T-con, but the cost is UGHH!! so I want to have a good feeling before spending the money

[dick_barton]

Re: Bang&Olufsen 6-26 with strange picture

Have you lifted (removed) one of the Tcon to Panel ribbons to see if you have a good half picture. Then reconnect and try the other ribbon?

[olegeisler]

Re: Bang&Olufsen 6-26 with strange picture

Have you lifted (removed) one of the Tcon to Panel ribbons to see if you have a good half picture. Then reconnect and try the other ribbon?

No, I didnt - but now I have :

1. Left disconnected, Right connected : Intermittent "triplicate" half picture / OK picture - just as with both connected, just only picture in one side.
2: Right disconnected, Left connected : Black screen, no picture at all ( first thought I did not re-connect properly, but reconnecting right gave the below result):
3: Both reconnected : Back to square one, intermittent triplicate at startup

Does that give any clues ?

[dskall]

Re: Bang&Olufsen 6-26 with strange picture

I would concentrate on t-con. Wiggle lvds cable to see if it has effect. Measure various voltages on t-con when picture good compare voltages to bad picture. Since you can replicate failure you should be able to compare readings from different boards when good and bad.

[olegeisler]

Re: Bang&Olufsen 6-26 with strange picture

I would concentrate on t-con. Wiggle lvds cable to see if it has effect. Measure various voltages on t-con when picture good compare voltages to bad picture. Since you can replicate failure you should be able to compare readings from different boards when good and bad.

Only voltage to the Tcon is a 5V, it measures 4.89V to 4.92 Volts.

Took a measurement on the first LVDS RIN0- and it looks like PIC 8 with "good" picture, and like PIC 9 with "bad" picture.

I also checked the clock, it is approx 84MHz "good" ( PIC7 ) and 65MHz "bad" ( PIC 10)

My conclusion is that the fault is somewhere on the mainboard / video process board, not Tcon / panel.
Please correct me if I am wrong.

And no schematics exist.

[dick_barton]

Re: Bang&Olufsen 6-26 with strange picture

Was that with the LVDS cable removed from the Tcon (or mainboard) to eliminate the possibility that the Tcon is corrupting the signal.?

[olegeisler]

Re: Bang&Olufsen 6-26 with strange picture

Was that with the LVDS cable removed from the Tcon (or mainboard) to eliminate the possibility that the Tcon is corrupting the signal.?

No, measured on Tcon.

Removed ( with power on ) , and checked the clock, it is 65MHz both measured directly on the cable and on Tcon.
Reconnecting the LVDS "live" does change the pictre, still "triplicate"

Thanks for your answer :-)

[CapLeaker]

Re: Bang&Olufsen 6-26 with strange picture

Try heating or freezing parts of the main board. I guess we need more pics.

[dskall]

Re: Bang&Olufsen 6-26 with strange picture

Well troubleshooting t-con is above my paygrade, but seems a 20mhz change in clock is beyond tolerance.

[olegeisler]

Re: Bang&Olufsen 6-26 with strange picture

Update for anyone interested : Heating / cooling seems to have no effect. Error occurs randomly !

BUT : I now purchased a set, which should be in poor physical condition, but functional. Will update when I find the solution !