M400 controller has lost it's display:

[CNCIT]

Hello all.

Overnight, my M400 display has gone from working perfectly fine, to 100% blank.

The backlight is working, but there is nothing at all showing on the screen. If I could not see the screen brighten slightly when I turn on the machine's power, I would just assume it was off altogether, judging by the way it looks

I would assume that either the LCD has gone bad, or the VGA chip is not producing any signal.

Is anyone familiar with the troubleshooting procedure, and/or would anyone like to venture a guess as to what replacement parts I need to purchase?

Thanks. Any help is appreciated.

[cncsnw]

I assume, since you present this just as a display issue, that the control functions correctly: you can jog, home, run the current job, etc.; you just cannot see anything on the screen.

In your generation M400 (ca. 2000-2001), the screen image data gets from the motherboard to the LCD panel via a ribbon cable and a "descrambler" circuit board, connected to the LCD panel behind the left edge, as viewed from the front.

For some insight into the assembly, see:
http://www.cncsnw.com/PC104M400Service.htm
and
http://www.cncsnw.com/M400LCDBacklight.htm

However, you could first try reseating the ribbon cable on the descrambler board, without significant disassembly. Using a technique similar to how I opened the top of the console in the above backlight replacement procedure, loosen the console face and swing the left side forward an inch or two, while leaving the right side attached but slightly loose. That will expose the descrambler board and the ribbon cable connection. Unplug and replug the ribbon cable; then reach beyond it a half inch or so and squeeze the descrambler board's connector firmly into the back of the LCD panel.

If that does not resolve the issue, then you probably have a failed descrambler board; a failed LCD panel; or a failed motherboard. Depending on your motherboard model, you might be able to try connecting an external VGA monitor.

For further troubleshooting, or possible replacement of the descrambler board or ribbon cable, you will need to know your motherboard model. See http://www.cncsnw.com/Motherboards.htm#PC104

[Mattwo_support]

Some systems have a pigtail with a VGA port. You can easily connect a monitor to that. If you do need to order a new descrambler board from centroid have the 6 digit code on the board ready.

[CNCIT]

Thank you, you've both been very helpful.

CNCSNW: There may indeed be more wrong than just the video display.

I checked it over again this morning, and was not able to reach any sort of satisfactory conclusion.

Here is what I found: #1 this unit has a different (replacement?) motherboard from what you described as standard for this model, and the LCD is connected directly without a "descrambler" board. There is no ribbon cable on this one. It is a regular multi wire cable, that plugs in to the top of the LCD from what I could see.

#2 Again, the LCD backlight works, but the screen itself is just black and lifeless.

#3 The motherboard beeps when I plug it in, and a pair of miniature LEDs (one green, one red) beside the power receptacle light up and remain lit. The membrane control keyboard seems to work, in that the motherboard beeps anytime a key is pressed.

#4 The control board seems *not* to be working, although I couldn't figure out any practical way of checking it.

#5 The jog panel seems to be totally dead. That is; all the buttons are non responsive, and none of the buttons with LED indicators will light up. The jog panel appears to receive its power from the control board...

#6 I reasoned that maybe the power supply could have failed on one or more outputs, and perhaps that could be the problem. But I checked it thoroughly, and all the outputs are within tolerance of their expected voltage numbers.

#6 This may not be related, but the drive board smells a little more like it may have a burned up component that what I would consider normal. Also, as I'm sure you know, there are eight LEDs on the left edge. According to the legend beside them, when the machine is idle, the four green ones should ordinarily be lit, and the four red ones should be off. In this case however, one green one is on, and all four red ones are on also.

I have described the situation the best I can. Hopefully you can make sense of it. I also have pictures of the boards, etc, and I will post them as well, if I can figure out how.

Thanks again. I really appreciate your help.

[CNCIT]

Here (hopefully) are the photos:

[cncsnw]

That is looking like a motherboard failure. Unfortunately, there are no readily available replacements of that type. You will either need to scrounge far and wide for a suitable PC104 motherboard; or you will need to look at upgrading the control (e.g. with Allin1DC+DC1+PLCADD1616).

The LED display on your QUADDRV1 servo drive is normal, for the condition where it has logic power, but the PC software has not yet initialized the CPU7 board.

[CNCIT]

Ouch..!

Well thank you for the reply. That's obviously not what I was hoping to hear, but it's certainly food for thought.

Tell me; I have several all in one touchscreen computers here... Is is possible to use one of those as an operator interface? Looks to me like the biggest issue would be interfacing it with the control board? On the other hand, I do like having the actual physical buttons for jog control, etc...

Thanks again for your help.

[cncsnw]

To keep your existing cabinet components (QUADDRV1, Optic232, Koyo PLC and PLC 3/3) you would need to be running CNC7 or CNC10, using either your existing CPU7 board (which plugs into a PC104 ISA receptacle); a different CPU7 board (which plugs into a standard ISA slot); or a CPU10 board (which plugs into a PCI slot). See http://www.cncsnw.com/CPUs.htm

It is unlikely that any modern "all-in-one" computer will have any of those expansion slots available.

[CNCIT]

CNCSNW you are absolutely a fountain of valuable information.

I guess I was hoping to be able to utilize something like the MPU11 board with an all-in-one computer. The main reason I like to use the all-in-ones, is because that is the cheapest way to acquire a touchscreen system.

Okay, at this point I am going to search all the sources I know of for a good used motherboard, as I would like to keep the cost of the repairs down to a minimum, and avoid any reprogramming chores that I possibly can.

Failing that, I would love to hear you suggestions as to what might be my most practical and economical route to get this machine back on its feet and in optimum working order, while preserving the control's professional appearance.

I realize that my questions are syphoning away some of your valuable time, and I appreciate your efforts. So if I owe you anything for that, just let me know.

[tblough]

Unfortunately, those motherboards are not made anymore so you would only find new, old stock, or a used working salvage motherboard. Both would have the same age related problems you are now experiencing, and no guarantee that the same failure would not occur with the replacement in a short time.

As previously mentioned by CNCSNW, your best bet is to replace the MPU11 system with an AllIn1DC. You might be able to reuse the monitor, and I believe Centroid can re-program the operator control panel to work with the new AllIn1DC. However, given the age of the monitor, and the probability that the membrane keypad is probably cracked and worn, it would be in your best interest to replace those as well.