Digihome 32DLed906

[dick_barton]

Re: Digihome 32DLed906

The two solder joints don't look that good and I would run an iron over them again, then I would test by attaching the led tester to the connector end that plugs into the led driver board so as to eliminate any problem with connections within the panel.

[ronhayes]

Re: Digihome 32DLed906

I have just run iron over them two joints. I have tested them that way as can be seen in post #93
And the test budm said to do is shown in post #78 if I am understanding it right there is no voltage increase !

[ronhayes]

Re: Digihome 32DLed906

In post #78 in my measurements the cathode wire end was 02,0v on St/By and 02.0v when powered on in the 200v range there was no jump in voltage.

[budm]

Re: Digihome 32DLed906

You have 140 feeding the Anode pin of the LED string but you only get 2.0V on the Cathode pin of the LED string return line, then there must be bad connection some where. It is impossible to have 140V feeding the LEDs which is much higher than the Total Vf of the LED string which is 36 LED x 3V = 108V Vf.
Something is not adding up, has to be error some where in the LED string.

[ronhayes]

Re: Digihome 32DLed906

I know it doesn't add up ?
But if you look at post's #91 and #93 when I connect tester to points on connection board and in post #93 to driver end of connection leads all works well all Led's have a steady light .
And given the voltage inputs on driver board these backlights should come on when set powers up ?

[budm]

Re: Digihome 32DLed906

I do not know what to tell you you have input Voltage to the string but you barely getting anything coming out at the other side of the LED string.

[ronhayes]

Re: Digihome 32DLed906

What I have just tried I soldered two fly leads from the anode and cathode on the connecter board what the Led strips push on to and soldered the other ends to the anode and cathode of driver board .
Then measured voltage on anode of driver board while powering up TV when button pressed the voltage went to 24.8v then after 5 0r 6 seconds it jumped to 117v and the back lights came on for a couple of seconds and as the voltage was slowly decreasing back down to 24.8v they go off they were not coming on before at all .
I also measured the volts on the cathode whilst carrying out the same test and stayed at 3v this time.
I think I need to remove the connecter board and carry out the mod that I posted in post #89 to see if this has any effect .
I will do this tomorrow.

[budm]

Re: Digihome 32DLed906

OK, that is not the same result with 140V reading which you had before which I do not understand why you are now getting 117V with flying leads connected to the same LED connector. When the Voltage drops down to 24.8V at that point you will not be seeing much Voltage on the Cathode return side.
The 24.8V is the feeding Voltage to the boost converter that put out over 100V to drive the LED string, the Vf of the LED string is about 108V (36 x 3V) + ABOUT 10V Vdrops on the PWM controlled MOSFET and the I sense resistor.
Right now it does not make sense on what you did with the flying leads VS direct connection between the LED strips from the panel to the power supply board via original wires.
You have to be get the same result using original wires without using the flying leads first.

[ronhayes]

Re: Digihome 32DLed906

What's baffling me is if I connect Led tester to the driver end of the connection wire all the Led's light up as seen in post#93 but when reconnected to driver board they don't .
It's weird .
O well I will see if I have any better look tomorrow.
What I would like to know is if my mod works could I leave it like this as long as the wires tidy and taped down, or would I have to replace connecter board ?

[ronhayes]

Re: Digihome 32DLed906

Here are some pictures of the fly leads . Just by-passing the connection on driver board and the lead from driver board to strip connection board and connection on board.

[budm]

Re: Digihome 32DLed906

Yes, you use that flying leads like that for now so we can do more trouble shooting as to why it goes into shutdown.
I have a feeling if you check the resistance between each corresponding pin on the power supply board to the LED board, you will find no connection or high resistance between the two pints, or you can have one flying lead connected one at a time to find out which original connection is bad.

[ronhayes]

Re: Digihome 32DLed906

So am I understanding this correctly , do I reconnect this lead as shown in attached picture ? then set dmm to ohms 20k range de-solder one fly lead on connecter board then check resistance from that pin on connecter board to corresponding pin on driver board ? then do the same with the other pin ?

[flocko]

Re: Digihome 32DLed906

I told you in post 35 that your driver boards were shutting down and the reason why. your new LED tester will light the backlights as it does not work in the same way as the driver board,the fact that the leds flashed on when driven by the driver board shows it to be working, your problem is with the LEDs or the wiring to said strips Hope this is of help

[vinceroger69]

Re: Digihome 32DLed906

ron you have said you have two led driver boards are these the exact part numbers just wondered if was different as maybe meant for more or less leds.

[ronhayes]

Re: Digihome 32DLed906

What I have now done is removed the strip connecting board and wired all the Led strips as illustrated in post #89 and then powered up. Led's light up after 5 seconds then go out after a couple of seconds . I then disconnected one strip and bridged across then powered up again the three remaining strips came on after five seconds but then go off after a couple of seconds , I then reconnected that strip and did the same procedure for the next strip I got the same results ! I then tried this on all the remaining strips only to get the same results the three connected came on after 5 seconds then go off after a couple of seconds. I then changed the driver board for the other driver board and the same results.
I just can't fathom this out (I even switched anode and cathode over on driver board )
but the Led's did not light at all. just to see had I connected wrong.
I then connected the fly leads from the driver board to each strip one at a time and I got the same results on each strip would come on after 5 seconds then go off after a couple of seconds this was the results for all strips ?

[ronhayes]

Re: Digihome 32DLed906

You know this is going to be a stupid fault in the end maybe a fault I have created I don't know but you can guarantee it will end up being a silly mistake in the end !! I just can't see the wood for the trees.
Will have a break for an hour see if that helps .

[flocko]

Re: Digihome 32DLed906

One dry joint on any of the replaced LEDs will see the driver shut down.And taking shots in the dark will not end up in a good place, putting 100+v though a strip that should run at about 25v. just as well the driver shuts its self down or you would need more new LEDs

[dick_barton]

Re: Digihome 32DLed906

Were the last few tests carried out with the main board disconnected and only the jumper resistors in place?

[ronhayes]

Re: Digihome 32DLed906

No the main board was connected up ready for normal use as when all Led's were replaced did not expect to have had this issue ?

[ronhayes]

Re: Digihome 32DLed906

I have just refitted the jumper resisters in place and disconnected the connecter from the main board and plugged TV in to a power outlet, So should I assume when TV is plugged in the secondary voltages should come up meaning Tv would be on and not in a ST/BY mode as the ST/BY on/off pin 6 is jumped to the +5v ST/BY pin 14 via a 1k resister ? and backlights should fire up due to pin 8 B/L on/off jumped to +5v ST/BY pin 14 ?
Because I do not have the 25.1v on pin 1 of the driver input connecter.
And if plugging TV into a power outlet powers TV into ST/BY mode how do I power TV out of ST/BY when remote sensor and on/off switch are connected to the main board ?