[Nth]

I hope you have access to an oscilloscope because it is the only good way to track down this problem. The relay clicking is probably the spindle power relay. I'd start by looking at the enable signal coming from the computer and make sure it is strong and solid. The interference the controller boxes can kick back is a prime suspect because of the chattering you are seeing. I (think I) remember that the limits switches and/or estop signals were hardwired to shutdown the spindle in the mill so next I'd scope them for intermittent shorts. Either of those lines could cause that relay to actuate but not have the TTL level to fire a signal to controller for the software to see and shutdown the enable signal.

[Chas R]

Thanks much for the reply, Nth. And again, thanks to your posts I was able to repair one of my controllers quite easily (diode replacement). I do have a scope so no issue there. Perhaps I should clarify some. This problem only occurs with I'll call it Controller B. With Controller A installed everything works perfectly, so with my very limited troubleshooting experience with these machines tells me the problem is in the controller? That said and since my post, Intellitek has done troubleshooting on Controller B and they tell me the problem is likely due to a ground loop or bad trace on the control board. So in lieu of having them work for possibly many hours at their shop rate, which could wind up exceeding the cost of a refurbed board, or worse a new board, I decided to have them stop and return the controller and I would do the tracing work. They also tell me there is actually very little on the board that controls the spindle and that the PC does most of it. Do you know this to be the case? Interestingly enough, the tech at Intellitek told me that for grins he connected the spindle power cable to Accessory 1 plug and it worked fine. I'm not sure I really understand why that would be but when I get the controller back home we will look into it very closely. Are there any schematics of these controllers out there? When I get the box back I will certainly work your recommendation. Thanks.

[Nth]

If the tech fixed the problem simply by moving the power connector for the spindle to acc1's plug then I'd suspect the spindle's SSR or one of the buffers/couplers upstream. Check the power coming out the SSR. If it is glitchy then scope the red and black signal wires to the SSR and see if there is noise. The SSR's signal is buffered by a hex inverter (DM74 on my board). There is a group of 4 of these U13 to U16 on the controller's PCB. In my notes U16 handles the SSR's. The spindles' SSR should be pin 6 (input pin 5). Check all return paths and connectors too.

[Chas R]

Thanks for info. Question: You refer to U13 thru U16 as inverters. When I track down the parts using the number on them, the nomenclature used is "Triple Input NAND Gate". On my boards they are ID'd as 74LS10N. Are we talking the same parts or not? thanks, -cr

[Nth]

I was thinking of the wrong chips. U3, U4 and U5 are the inverting buffers. On my board U13, U14, U15 and U16 are 74LS00N's(quad, 2 input nand gates). If your board uses triple input nand gates then it is a different revision than mine and you'll have to trace the pins yourself.

[Chas R]

OK makes sense. Not sure if mine are older or newer. We are fairly confident the spindle SSR is the culprit and I have one on order, should be in next week. My guy here has a Huntron 1200 which was a big help. We are a little disappointed with the manufacturer's repair service though. In a phone call I was led to believe they would fix just about anything wrong with the board for around $200. Turns out once they got it on the bench they were more interested in selling me a used board for $600 or a new one for $1000. Will advise on how the replacement SSR works out. Thanks again for help.

[Chas R]

Replacement of the spindle SSR did the trick. Got a new one for 14 bucks and now the box works like a champ. Still, I'm disappointed in the level of service from the box manufacturer. Their guy said the SSR checked out fine. I think they just wanted to sell a new board.