Repair Journal | JVC LT-42X579 (one of many affected models)

JVC LT-42X579 | 42" LCD TV

SYMPTOMS: Relay clicks when powering unit on, but no picture appears and the power LED flashes on and off slowly.

DIAGNOSTICS: Although this did at first seem like an issue with the power supply, the problem lies within the programming itself. From the factory, the TV only allows a 10 second window for the power on sequence. If it takes longer than 10 seconds, the TV goes into protect mode (LED flashes on and off slowly).

SOLUTION: This is a simple fix. You must enter the factory menu and follow these instructions carefully. The goal is to change the data at EEPROM address 18 from hex value "a" to "28" to allow for a larger window for the TV to boot up (10 seconds -> 40 seconds).

Instructions for EEPROM address change

1. Unplug TV for 10 seconds.
2. Plug in the TV.
3. Using the buttons on the TV (not the remote) hold [MENU] and [VOL-]. While holding them, press the [POWER] button once and continue holding [MENU] and [VOL-] for 3 more seconds before releasing.
4. The blue power LED on the lower left of the TV will turn on and remain lit. Sometimes, the TV will complete the power up sequence from here and will show an image after 30 seconds (so wait a little bit). If this is the case, skip to step 6. Otherwise, continue.
5. Unplug the TV for 10 seconds. Plug it back in and wait approximately 30 seconds for the set to display video.
6. Using the [SLEEP] button on the remote, make sure the TV is set to "sleep timer off," which will be displayed in the bottom left corner of the screen.
7. While the TV is still displaying "sleep timer off" you must press [DISPLAY] and [VIDEO] on the remote simultaneously to enter the factory menu (Note: Instead of [VIDEO], use [V.STATUS] on controls which don't have a [VIDEO] button - Thank you very much to Calvin Dodge for this tip). If it doesn't seem to be working, just keep trying. It can sometimes be finicky. It's not supposed to be easy to get into.
8. Once the factory menu appears, use the arrow buttons on the remote to navigate to "M16 EEPROM EDIT."
9. Press [OK] and the edit window will appear. You should see two lines. On the first it will read "EEPROM Address" followed by a box with a lower case "h" next to it (for "hexadecimal"). Similarly, the second line will say "Data" with a box and an "h" next to it.
10. Using the [UP/DOWN] arrows on the remote control will change the value in the selected line's box. The [LEFT/RIGHT] arrows will switch between "Data" and "EEPROM Address." You must now set the EEPROM Address to "18" then change the data at that address to the value "28." Press [OK] to save the data change.
11. Press [BACK] several times to exit the factory menu and power off the TV.
12. Turn it back on and get back into the factory menu (sleep timer off, press display and video simultaneously) so you may check the data at address 18 (you must navigate to it again to check). If it is not correct (28), return to step 5 and try again.

This procedure should allow for 40 seconds instead of 10 for the power up sequence and solve the issue. As always, please feel free to ask me any questions you may have in the comments below!

Other affected models:

LT-32E479/S
LT-32E479/SB
LT-32E479/V
LT-32E479/VB

LT-32EM49/S
LT-32EM49/SB
LT-32EM49/V

LT-32P679/S
LT-32P679/SB
LT-32P679/V
LT-32P679/VB

LT-42EM59/C

LT-42P789/C

LT-42SL89/V

LT-42X579/C
LT-42X579/Z

LT-46SL89/V

LT-47EM59/C

LT-47P789/C

LT-47X579/C

LT-52P789/KA

LT-52X579/KA