Digihome 32DLed906

[vinceroger69]

Re: Digihome 32DLed906

just a thought as ron has got this far in repairing this set what about seeing if we can adjust the under voltage/over voltage protection so maybe budm etc can advise if this safe to do and can even be done.
http://www.rohm.com/web/eu/datasheet/BD9285F/bd9285f-e
https://www.badcaps.net/forum/showthread.php?t=61722

[ronhayes]

Re: Digihome 32DLed906

Hi All
Just updating on this set!
I decided to go ahead and order some replacement Led strips thought well I have come this far I might as well carry on (as they say don't let it beat you)
They arrived today so when I returned from work I decided to install them.
Well when installed I switched on the set and would you believe it I still have the same issue backlights come on after about five seconds they go off again in a couple of seconds, I have tried both driver boards and I get the same results with both boards.
Now I know these are not new Led strips they are used, but on inspection they look to be in good order and not had any Led's changed they also came with the connection board and the connecting lead, also they all light up when they come on.
Does any one have any thoughts on what else could be the issue with this set ?

[budm]

Re: Digihome 32DLed906

Did you verify that the BL-ON and the Dimming control signals are still present when the backlights go off?

[ronhayes]

Re: Digihome 32DLed906

Can these signals be measured with a dmm or do I need to use a scope?

[budm]

Re: Digihome 32DLed906

They are just DCV, so DMM will do.
BL-ON is usually <1VDC = OFF, > 2~2.5VDC = ON
PWM = 1V ~3V range.

[ronhayes]

Re: Digihome 32DLed906

Unfortunately i am on the dreaded afternoon shift this week so can only work on this set on the evening after 10pm for a few hours !
I will check these volts tonight and see what is happening and post my findings then.

[vinceroger69]

Re: Digihome 32DLed906

budm on these sets is it possible to disconnect the main board to rule out it being faulty, and jump the psu with resistors so he can just test the backlight circuit? i know dick-barton was trying this earlier on in the thread but wasnt certain about what pins to jump using resistors as vsetel psu s dont always match schematics.

[budm]

Re: Digihome 32DLed906

budm on these sets is it possible to disconnect the main board to rule out it being faulty, and jump the psu with resistors so he can just test the backlight circuit? i know dick-barton was trying this earlier on in the thread but wasnt certain about what pins to jump using resistors as vsetel psu s dont always match schematics.

Yes, the power supply/LED driver board can be tested by itself, just need to know the pin labels/name, and if it is Active high or Active low.
But at this point since he did get the backlights to come on then all he has to do is to leave the meter connected before turning on the TV and watch the reading when the baklights come on and when they go off.

[vinceroger69]

Re: Digihome 32DLed906

budm im still learning myself so bear with me, ive just been looking at the schematic
it has bl-on/off listed on pin 12 pl804 connector on the psu and also bl-on on pin 8 of pl805 connector on the psu so i was just wondering why it has two bl-on/off connections on the psu.

[budm]

Re: Digihome 32DLed906

I will have to look at the schematic, your post #2, right.

[vinceroger69]

Re: Digihome 32DLed906

I will have to look at the schematic, your post #2, right.

yes but as we know vestel psu schematics are not the best at times

[ronhayes]

Re: Digihome 32DLed906

Hi All
Sorry I am late tonight but did not get out of work until late.
Firstly in answer to vinceroger69 the question you asked budm why is there two bl-on/off listed one on pin 12 pl804 and pin 8 pl805 I can clear this one pl804 is the connection plug to the backlight driver board and pl805 is the connection plug to main board.
Now I have tried testing volts on pin 8 of pl805 on st/by the reading is 0.40v and when you press on button on remote the reading goes to 0.20v readings taken in 20v range and what is strange is the backlights fail to flash on . If you remove the probe they fash on after 6 or 7 seconds when pressing on from remote.

[vinceroger69]

Re: Digihome 32DLed906

Thanks ron, budm i think also needed b-dim reading too pin 10 on pl 805 can you test that voltage as well
I think as dick-barton was suggesting, we may need to start by just testing all the psu output voltages without the main board connected maybe budm will advise which pins to jump with resistors.

[vinceroger69]

Re: Digihome 32DLed906

Thanks ron, budm i think also needed b-dim reading too pin 10 on pl 805 can you test that voltage as well
I think as dick-barton was suggesting, we may need to start by just testing all the psu output voltages without the main board connected maybe budm will advise which pins to jump with resistors.

added picture of mainboard connector

[ronhayes]

Re: Digihome 32DLed906

Vince
I have just measured pin 10 pl805 and I get 0.00v in ST/BY and goes to 3.42v when powered up when back lights come on it drops to 3.02v then just before the backlights go out it slowly goes down to 0.00v again it seems when this voltage starts to drop out it switches the backlights off ?

[vinceroger69]

Re: Digihome 32DLed906

its got to be too do with the bl-on voltage being so low if we can force on the psu we can see if the faults on the psu

[ronhayes]

Re: Digihome 32DLed906

Yes it seems that the bl-on volts are turning them back off. I think when I find what is causing it and hopefully cure it I will then try the strip lights I repaired back in to see if they work, As this fault put me doubting that I had repaired them correctly ?

[vinceroger69]

Re: Digihome 32DLed906

ron ive just read the whole thread and noticed you have changed the original main board was it at fault as the mainboard i think sends the signal to turn the back lights on, thats why i was trying too get you help on how we can force the psu on and test the backlight circuit without the mainboard being involved.

[ronhayes]

Re: Digihome 32DLed906

Yes I think it was as the original fault was blinking st/by light set would not power on .
But you saying that I do have a couple of boards so I will have a look through them and see if I have another board to try ?

[ronhayes]

Re: Digihome 32DLed906

Vince I just found the original board and tried that back in again, and got original fault st/by light blinking and nothing happening when you press power button.
I also found another board that looked similar but not exact tried that one and nothing not even st/by light.