2023-07-13: If, in the course of owning a Protrak Knee Mill with the KMX control, you should run into a weird problem where the WDT_fault light is doing a fast blink, you may want to keep reading. The prototrak in question has spent most of its life crated up, never unpacked. It was made in 2017 and only unpacked and powered up late in 2021. It sees weekly use, but is otherwise powered down. It fired right up and did a couple hours of work on Tuesday, but when turned on Thursday, I was greeted by a completely black screen (backlight on) and the WDT_FAULT light doing its fast blink.

Our first step should be to check the manual: its a Watchdog fault... Of course a reboot did not fix the problem. Still a blank screen. A quick call to Southwestern industries and Leo tells me they offer a complete control swap for $1290.00. No parts; no additional troubleshooting steps. Turn around time of a couple days. Now anyone doing machining knows that the only reason you fired up a machine is to do a job that a customer wants right now...a week's waiting won't help. I'll be the first to mention that I really should have been taking pictures, but that was the least of my worries at the time. I'll also skip all the un-necessary troubleshooting steps I took and the 3 hours it took to get to this point...

Do yourself a favor: grab a multimeter and measure the voltage of this battery. If it is below 1.5v or so, the computer will not start up at all. Removing the battery does not help either - the computer must have a new one. Pull the board, taking care to mark the direction of all the little display wires, serial and USB headers. Then take the board to any local electronic repair shop to have the battery replaced. It cost me $6.00+tax. And I had to de-solder / solder it myself. Reassemble and turn the control on. If you're lucky, like me, you'll have a fully working control again.

I placed another call to southwestern industries to ask about proper BIOS settings, since they had been obviously wiped by the dead battery. I had set the watchdog timer to enabled. (DON'T DO THAT!!! - the machine will reboot or lock when the timer triggers). They seemed genuinely confused by the question and told me they do not change any settings in the BIOS at all. They also told me a dead battery shouldn't cause the machine to not boot and that they had plenty of older SMX and KMX controls out there. They also said it was the first time they had ever heard of a dead battery in the controls. (First time for me; first time for them!) I can't argue with their experience, but I can show them my now working control after a battery replacement. I can also show them what happens when you disconnect the new battery... (dead/unresponsive control again)

Oh, and this single board computer is kinda neat - feel free to geek out a little!

and if you forgot to mark the one header...Here you go... this is the correct orientation (look for the white dots!)