MCA white screen

[uscovu]

Hello guys,
today I receive one MCA unit with white screen, touchscreen works fine (if you guess where the buttons are) but there is no image. It is not a update fail or something like that, it has happened while the was running on highway. The display it is good because I tested on other unit (NX), there is no physical damage or burned circuit/component.
Maybe there is someone who had fix this issue....
Since I don't have schematic for this units, tomorrow I will teardown my own MCA from my car and make some measurements and compare values and hope to find the problem and fixit. If I succeed to repair I want to try to retrofit camera input using Go4IT tutorial.

All best.

[Go4IT]

Does it look like this?

screen_defekt.jpg

mca_white_screen.jpg

[uscovu]

Nope, full white. I saw this kind of milky display and it was from display ribbon. The guy said that it wad driving on highway and the display became white instant but he could change the radio station by the touchscreen.

[Go4IT]

I also got two devices with this problem here, one MCA and one NX, both the same issue and it is defenetely a problem on the graphicsboard, not the LCD ribbon cable from the TFT.

[uscovu]

Have you managed to fix the problem?

[Go4IT]

Not yet, but i haven't spent time to it. I suspect the problem in the voltage driver area. One of the voltages may not like wanted. Go ahead an compare from the TP's. Only thing is that the device must be started from the power knob, because otherwise the TFT voltages are not enabled.
Also beware of the high voltage converter for the background CCFL, it could have 1kV and more. Don't get close to this with your fingers!

[uscovu]

So, today I had some limited time and made measurements, I found a shorted 1uf cap. Now I see some vertical lines on display
Before that, when the power button was pressed I was able to se a very short change of display (black) and then turned off and remain only white screen. After this I was 100% sure that it is a shorted component somewhere.

Will continue tomorrow.

[Go4IT]

Which one was it? Partnumber?

[uscovu]

C2036 measured 1.8 ohm, this prevented to power up de LCD. Now I measure 10v on UVLCD but I must be 20v. D2003 (MC34063EB) is a small inverter witch rise the voltage from 5v to 20v. I think, this is the reason of no picture, not enough power.

[Go4IT]

Sounds reasonable. Have you tried to replace D2003 and the defective cap also? The cap is located nearby some surge protections diode array. Maybe there was an overvoltage due to a malicious battery regulator?