Screen: Apparent lack of backlight and screen display on car 57

[jlandau10]

Entire WaiveScreen has been removed, with the suspect display and electronics separated from the screen for troubleshooting.

[jlandau10]

On vehicle it appeared that both the backlight and display were out, which seemed highly improbable due to the independent nature of the two circuits. On the top (when screen is open) display it is easy to tell if the backlight is illuminated due to the visibility of holes to the LEDs, on the bottom screen this is not possible. Removing the display plug from the test screen, from the front it appears as though the screen and backlight are both off, despite clearly being able to see the backlight illuminated from the rear.

Troubleshooting steps: using the backlight power pcba and the removed display, i connected 13.5V to the pcba and plugged in the LEDs, touching the ON/OFF pin high resulted in all LEDs turning on. One plug per string of the board was used validating all strings. This indicates a likely issue in the display circuits themselves, either the rigid or rigid-flex breakout pcbas.

[jlandau10]

Swapped rigid pcba with test screen and pcba functions properly.

Remaining possibilities:

• rigid flex PCBAs to the 6 individual screens in one display or the interconnect to the rigid PCBA. losing either one of the connections to the rigid PCBA takes down the screen.
• HDMI to display PCBA and connections. in the on car troubleshooting we swapped the hdmi cable from the MoBo to the working display with no issues, however this is the output from the MoBo not the output to the screen so it did not exonerate the HDMI to display PCBA or the connections there. It does, however speak to this not being a mother board issue.

[jlandau10]

HDMI to display PCBA (BSD.E6AVL-BN) troubleshooting: swapped both BSD.E6AVL-BNs from the dead screen (not sure which one went to top/bottom) into the test screen one at a time and both worked properly, exonerating those boards.

This leaves two remaining possibilities, either the rigid-flex PCBAs are damaged or there was a connection issue somewhere between the BSD.E6AVL and the rigid-flexes.

[jlandau10]

took the dead screen and hooked it directly to the test screen's backlight board and BSD.E6AVL-BN. Confirmed that backlights are working and screen output is not.

Remaining possible problems are all upstream of the rigid pcba in the screen starting with the two ribbon cables.