Hitachi LCD, LE40K507, no standby light

[kyrinth021883]

Hello, I have tried to trouble shoot and have thrown some parts at it, but I am not having any luck. I have a Hitachi, model LE40K507, LCD tv. The discrepancy is: TV is plugged in, and nothing. No standby light on the front, no response from power button, nothing. I have changed both a power supply board and the main board. (I have not yet changed the digital board, aka PC board unit) I open it up and measure the voltages from the power supply board while plugged in. They are as follows:

ON/OFF - 0.06 VDC
ADJ - 4.95 VDC
GND - N/A (No pin)

12V - 12.19 VDC
12V - 12.19 VDC
GND - 0
GND - 0
5V - 5.2 VDC
5V - 5.2 VDC
GND - 0
GND - 0
STBY - 4.86 VDC
5VSB - 5.2 VDC



These number almost look good to me and I would think I should be getting at least a standby light or something. I get nothing. Please help with any advice or anything else for me to check. Thanks in advance!

[budm]

Re: Hitachi LCD, LE40K507, no standby light

For us to help we will need good clear pictures of the whole backside of the TV showing all the boards, and the straight shot pictures of the whole top and bottom side of the power supply board so we can read the printed texts on the board.

STBY (PS-ON) - 4.86 VDC: Does this one change state when you toggle the power switch?
ON/OFF (BL-ON) - 0.06 VDC: No command ON to turn on the backlights.
ADJ (Backlights Dimming control) - 4.95 VDC
So far it looks like main board problem, but if you put the old main board back in, what Voltages do you get then?

[CapLeaker]

Re: Hitachi LCD, LE40K507, no standby light

yep, x2 what budm said. Hopefully you can return that replacement main board.

[kyrinth021883]

Re: Hitachi LCD, LE40K507, no standby light

here are the pics of the rear of the TV and the front of the power supply board. Also the rear portion that has the connector pin labels. Cant get a pic of the entire back. card has a stupid plastic protector on it.

STBY (PS-ON) - 4.86 VDC does not change when power button pressed. Nothing changes when buttons pressed.

Will swap main boards again tomorrow, it is late tonight. Then will post findings.

[kyrinth021883]

Re: Hitachi LCD, LE40K507, no standby light

Ok, so I put in the new main board that I ordered and strangely now I get no voltages other than the 5VSB. everything else is 0. Still no standby light and no response from the power button. Put the original main board back in and I get the voltages I had posted above. (The voltages I had above were with the original main board as well).

Not sure if I ordered a faulty main board or if it is actually correct that it shows no other voltages, and there is something else wrong in the TV as well.

[nomoresonys]

Re: Hitachi LCD, LE40K507, no standby light

Looks like you received a bad or non-compatible mainboard.

[CapLeaker]

Re: Hitachi LCD, LE40K507, no standby light

Bad main board. PSon and BLon come from the main board.

[budm]

Re: Hitachi LCD, LE40K507, no standby light

What you can do at this point with the old main board is to have evrrything connected but you will disconnect just the BL-ON wire going back to the main board and then use 1K resistor between 5VSTBY and the BL-ON pin on the power supply board.
When you power up the TV you should have backlights on and you should also see images on the screen if all other functions of the main board and the T-CON are OK.
Your replacement main board is bad or not the right one.

[kyrinth021883]

Re: Hitachi LCD, LE40K507, no standby light

Ok, just performed the simple 1k ohm resistor test. With the resistor between 5VSB and ON/OFF (BL-ON), the backlights come on steady and stay on. So no problem there. Checking the contact that i removed, and there is still no voltage there. So, am I correct in assuming that the main board is supposed to supply this 5VDC BL-ON when all other conditions are met and this might mean the main board is bad?

The main board I ordered matches everything part#-wise and model-wise, so not sure why it didnt work, other than they just sent me a dead board. Will see if I can return it and order a new one once I get your input on the info above.

[kyrinth021883]

Re: Hitachi LCD, LE40K507, no standby light

Ok, another quick question. Looking at the part number of the main board, i understand there are multiple versions/compatibility part numbers for the same model number. I am trying to better understand the part number itself. The suspected main board in my tv now is "E13090429-0A01375". When i search online for a new main board all I can find is the part numbers listed by the first half of the part number (i.e. "E13090429") they leave off the rest of it. Is the rest of this part number ("-0A01375") important of not? Do these numbers need to match as well? or just the first half of the part number?

Im thinking that is what happened with the first main board I ordered. They only listed the first half of the part number in the item description when I purchased it. But it has a different second half number (-0A04514, which is not the same as mine (-0A01375).

So like i said, im just trying to understand what that second half means. Is it a version compatibility number? different part number all together? or what?

Thanks for any assistance in helping me better understand this! If i order another main board, i want to make triple sure it is the right one lol

[budm]

Re: Hitachi LCD, LE40K507, no standby light

The P/N of the main board PCB assembly (PCBA) is printed on that bar code sticker, that is what you need to match.

[Andrew F. Ali]

Re: Hitachi LCD, LE40K507, no standby light

E13090429-0A01375 is the No. on the sticker with the barcode. I think the 0A01375 is relevant/critical for a replacement match.

[kyrinth021883]

Re: Hitachi LCD, LE40K507, no standby light

Ok, thank you for the info. I will search for a new main board with matching part number all the way.

[nomoresonys]

Re: Hitachi LCD, LE40K507, no standby light

Shopjimmy has two on this page both sold out, if you read it, says those certain numbers must be on your sticker, check both of the boards listed there. http://www.shopjimmy.com/catalogsear...t/?q=+LE40K507

[kyrinth021883]

Re: Hitachi LCD, LE40K507, no standby light

Update: Ordered new main board (ensuring the correct part #'s as I had done before). This time it worked. TV repaired and works like a champ. Thank you all for the assistance. This confirmed that I did get a bad main board the first time. I was able to return it for a refund.

[nomoresonys]

Re: Hitachi LCD, LE40K507, no standby light

Care to share who sold you the bad mainboard, or was it just not a match? if theyr selling bad parts I want to avoid them.