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Abnormal white screen after startup on MD4

Paul Summers 5 years ago in Master modules / MD4 updated by Gustav Widén (System support) 4 years ago 10

Has anyone else experienced a completely white screen on an MD4 after start-up but application file seems to work properly? The problem is very intermittent, it happened approximately three times during a week of testing a prototype (perhaps 100 boot up cycles).



Cycled ignition key off and back on to rectify.

Under review
Hi Paul,

What supply voltage do you have in your system? I have been able to replicate a symtom like this on the bench when ramping up the supply voltage very slowly from 0 to 9 V.
+1
we are having this problem right now on a piece of mobile equipment.

if the keyswitch is turned to ON (not cranking the engine) the module boots up correctly 100% of the time.
once the keyswitch is turned to engine start and the engine is cranking, the voltage will drop (unknown to what exactly) and then the MD4 will turn off and back on.

about 1/3 of the time it comes up with the white screen and not the regular loadup..... when the screen is white, even when the supply voltage is up around 14 volts (engine running at speed and plenty of volts/amps) it does not recover.

We have told the customer that it is a problem with the initial 'turning on' of the screen with low voltage and that it doesn't reset just by the voltage going above 12 volts (won't fix itself).

OEM isn't really thrilled by this but we have no other answers.

Any factory suggestions would be greatly appreciated.


David, I have had this issue recently with a third party device. If you have the ability to use a scope meter on the power supply, you'll notice that the power most likely drops below the Minimum allowable level. I have considered using a large capacitor and a diode in the +VDC power supply to the Module. this should be sized to hold enough power during engine cranking. also check your wire size, sometimes a larger AWG wire size can correct this issue
Only thing I would caution to make sure that in an emergency, that the system shuts down within a reasonable timeframe... I hate trading on problem for another!

We ultimately installed a Maxwell engine start module (basically a mission specific ultra-capacitor assembly) to the vehicles starting circuit to isolate the control modules from the cranking voltage drop. This is a very slick but expensive solution.
Paul, very good point regarding shut downs when required in emergencies.
Completed

The IQAN-MD4 board has been updated to prevent the problem of display latchup when slowly ramping supply voltage between 6-9 V. Implemented in production 2015-12-13

Hi, we have a display with a build number of 150825 and we have the same issue on a 12v system. Looking at the number, does this mean it was produced in august 2015?


Is there any way of modifying the circuit board or getting a replacement display unit?

There are too few digits in that serial number, you should see a SN with ten digits.

The first two digits are year, (e.g. 15 for year 2015), the two digits that come after are calendar week.

I didn't clarify, the 6 digits i quoted were for the production date. The serial number on the unit tells me it was build in week 35 of 2015 (1535). Is there any way wan we get this circuit board modified to resolve this issue?

No, unfortunately there is no process for reworking the old MD4 circuit boards to the new design that does not have this issue.