Hitachi LE55A6R9 LED Issue or?

**LITEZONER** · 06-09-2017, 10:49 AM

Re: Hitachi LE55A6R9 LED Issue or?

starting strings do not light up, they are the ones with the A7, if i disconnect the trailing string the trailing string will light up by it self, but the leading strip, the one with the connector to Power board will not light up as a string, only when i test each LED individually they will light up, so the A7 is blocking current to the entire string, Only the trailing string will light up all by it self with the tester, the leading string will not.

**dick_barton** · 06-09-2017, 11:32 AM

Re: Hitachi LE55A6R9 LED Issue or?

If you test using your meter set in diode mode ( --!<!-- ) does A7 look like a diode. High one way, 0.5 the other way?

**LITEZONER** · 06-09-2017, 11:46 AM

Re: Hitachi LE55A6R9 LED Issue or?

yes testing in correct polarity I get a high reading, I reverse the leads and get an open, this seems normal to me for a diode?

**dick_barton** · 06-09-2017, 12:12 PM

Re: Hitachi LE55A6R9 LED Issue or?

No. If it was a diode you should read 0.5 (approx) showing on your meter if it is set to diode mode when the probes are across it in one direction but high/open when you swap the probes.

**LITEZONER** · 06-09-2017, 12:28 PM

Re: Hitachi LE55A6R9 LED Issue or?

which begs the question what is it and what is it's purpose right. half wave length diode? printed adjacent to it is (STD Diode) I believe that must stand for standard diode I don't know. I have new strings, I will pull one out and test the reading on it

**LITEZONER** · 06-09-2017, 12:40 PM

Re: Hitachi LE55A6R9 LED Issue or?

Just opened the new set i bought from SJ, there are no A7 chips on them

**LITEZONER** · 06-09-2017, 06:06 PM

Re: Hitachi LE55A6R9 LED Issue or?

well, My apologies folks, i did find a bad LED lamp, I would have bet money that they all lit when i tested them, so I put in the new led strings and assembled the set and it's all good to go, as far as those diodes go I found out that they somehow reversed the polarity thus not lighting up the good strings in the set, just for fun I reversed the polarity on my testing probes and the lit up, I stand in embarrassed mode and a bit miffed, Oh well, Live and learn... just sorry to waste anyone's time. Have a good one.

**LITEZONER** · 06-09-2017, 11:04 PM

Re: Hitachi LE55A6R9 LED Issue or?

Unbelievable, worked for about an hour, then went out again, nice to test led's with this tester i have ruled them out. thinking driver on power board URG!!!

**dskall** · 06-09-2017, 11:54 PM

Re: Hitachi LE55A6R9 LED Issue or?

Did you have backlights turned down?

**LITEZONER** · 06-10-2017, 05:47 PM

Re: Hitachi LE55A6R9 LED Issue or?

not sure, I do not have a remote for this set, what if they were all the way down? I had a DVD in playing as I usually do, I like to let them run for 24 hours before I call it a successful repair.

**LITEZONER** · 06-21-2017, 07:12 PM

Re: Hitachi LE55A6R9 LED Issue or?

well this thing is wearing me out, Led tester on red and black string wires all led's light up, no voltage coming from terminal with red/blk wires, so i think LED driver circuit not working, checked all voltages across terminal plug and get all 12V and 3V working fine, Not sure what to check next.,

Attached Files

**budm** · 06-21-2017, 07:18 PM

Re: Hitachi LE55A6R9 LED Issue or?

https://www.badcaps.net/forum/attach...1&d=1498093933
Man! Can you take better pictures, they are blur and I cannot read any labels of the pins? I also need good CLEAR straight shot of the bottom side of that power supply board (pictures in post 5 are not clear enough to trace the circuits) and also pictures showing the whole backside of the TV so I can see all the boards.

**dick_barton** · 06-22-2017, 03:36 AM

Re: Hitachi LE55A6R9 LED Issue or?

Originally posted by LITEZONER

well this thing is wearing me out, Led tester on red and black string wires all led's light up, no voltage coming from terminal with red/blk wires, so i think LED driver circuit not working, checked all voltages across terminal plug and get all 12V and 3V working fine, Not sure what to check next.,

What voltages do you have at the diodes either side of which are next to the led connectors. Worth checking they are OK with meter in diode mode.

**LITEZONER** · 06-22-2017, 07:32 AM

Re: Hitachi LE55A6R9 LED Issue or?

diodes seem good there, current one way or open, and 4-5 in diode mode the other. here are some hopefully better pictures.

Attached Files