MD4 Graphical Error?

Kevin 6 years ago in Master modules / MD4 updated by Matthew Herzig 6 years ago 4

We have a customer that is experiencing graphical errors with an MD4. S/N 1535280044. Customer is complaining that the display sometimes is black, sometimes white and sometimes multicoloured lines:

Image 1324

Does anyone know why this could be happening? It appears to be happening sometimes at startup, but also when machine is running (randomly dropping out). Im not sure if its the hardware issue that was changed a couple of years ago on the MD4?


The symptom looks exactly like this one: 


The S/N also match, units built 2015 and earlier can have these symptoms when supply voltage is ramped slowly between 6-9V. 

Since you say it could occur with the machine is running, that indicates that the machine may have an issue with the  voltage supply to the MD4. 

We have been unable to reproduce the black screen or the coloured lines as shown above on the display. Is this likely the same issue as the white screen? The image above almost looks as if the display could be faulty rather than the issue with slow ramp in voltage?

I don't recall if there were any photos with multi-colored lines in the forum posts where this issue was discussed, but that was one of the symptoms. The slow-ramping on the earlier MD4:s could give either of the symptom white screen, black screen or multi-colored lines. 

That does of course not say that there couldn't be something damaged on this particular module that gives the same symptom. To evaluate the hardware for potential defects, the module would have to be sent for repair; check with the local Parker sales company. 


I ran into this back in late 2015 (when we were prototyping our first MD4-7!) on startup only and it was due to cranking voltage dropping too low on startup.  Testing at 1 millisecond I would drop from 12.8 volts to 5 volts DC when cranking.  At 100 milliseconds I would read 10.5 volts.  These very quick low voltage spikes were causing our screens to do the same as the picture you attached, and most of the time just a straight white screen.  I had the MD4-7 wired originally to stay powered while cranking, but ended up isolating it with it's own power relay to drop power while cranking and never have had a problem since then and have over 225 units out with the MD4-7 in them now.  Possible you are getting a high amperage spike in the system when running causing the voltage to briefly drop?