CNC Mill Tool arm - Page 1
Forum section: electronics / repair

author: Duesentrieb66
author_rank: Newbie
timestamp: October 07, 2023, 02:23:19 pm
content: Hello All!The toolarm of my cnc mill is not always coming out. To be precise: 9 out of 10 it doesn't. I didn't figure out any pattern: Temperature, time of running etc.while try to find the error I measured if there is enough voltage on the motor and accidently figured out a workaround:When the Fluke is in AC mode and I measure between pin 29 and 32 it ALWAYS works!While this hack gets me going during the week, when people are around to hold the fluke to the contacts, I can not work on the weekends when I am alone. I tried to add wires to the contacts JP11 2A and JP11 3A and the fluke. That DOESN't work - I littarly have to hold the pins from the Fluke to the contacts like in the picture shown. Strange...Does anyone has an idea how to fix this? Any suggestions are much appreciated!!Thanks, Duesentrieb

author: Grandchuck
author_rank: Super Contributor
timestamp: October 07, 2023, 02:56:00 pm
content: Printed circuit board/solder pad issue? The physical pressure makes it work?

author: Duesentrieb66
author_rank: Newbie
timestamp: October 07, 2023, 03:13:06 pm
content: good idea - thanks!I just made a small gcode what makes a slow move in X followed by a tool change. That gives me time to walk back to hook up the Fluke. i will try again and will not put any pressure on it.cheers!

author: KrudyZ
author_rank: Frequent Contributor
timestamp: October 07, 2023, 03:46:12 pm
content: Quote from: Duesentrieb66 on October 07, 2023, 03:13:06 pmOr just do what you did before, but not have the Fluke on the other side of the probe cables.In other words, it's very likely that you pushing in that location is closing a poor contact, either in the plug, the connector, the solder of the connector or a trace on the PCB.

author: Duesentrieb66
author_rank: Newbie
timestamp: October 07, 2023, 05:25:02 pm
content: I just tried that. Same probes, same pressure but no fluke attached.Doesn't work

author: KrudyZ
author_rank: Frequent Contributor
timestamp: October 07, 2023, 09:58:41 pm
content: Your 3rd picture shows two wires going into JP10 3A, but the schematics only shows one...Or is the extra wire going to the cap?

author: Duesentrieb66
author_rank: Newbie
timestamp: October 08, 2023, 02:09:17 pm
content: Right? I was asking this my self.Also, my gut feeling tels me that the cap 101 is the problem. But I can't find it anywhere, I would replace it.To me it ilso not 100% clear why there is a cap. Can someone please explain me why?Thanks!

author: KrudyZ
author_rank: Frequent Contributor
timestamp: October 10, 2023, 03:56:40 am
content: My guess would be the cap is introducing phase shift between the phases to change direction.One phase is driven directly and the other through the cap.

author: duak
author_rank: Super Contributor
timestamp: October 10, 2023, 04:36:54 am
content: That motor & the carousel motor are both reversible AC induction motors and the cap provides the phase shift. The cap is about 10 - 20 uF at a few hundred volts and is in a metal can or plastic cuboid screwed to the inside of the electrical enclosure. It could also be closer to the motor in a junction box. It could indeed be bad or at least lowered in value. HVAC suppliers or motor rewind shops should have something similar.Are the Grayhill 70M-0AC5A solid state relays socketed? One might be getting blinky and as a last resort I'd consider replacing or swapping the ones controlling the arm.Is this a Tormach or Fadal or ?BTW, I'm in Vancouver, BC and have fiddle farted around with various CNC machines since retiring.Cheers,

author: Duesentrieb66
author_rank: Newbie
timestamp: October 20, 2023, 03:15:02 pm
content: Thank you all for your time to help me!Grandchuck was actually right - when I press the board with pure hands it works as well. It was just bad luck when I tried first time or I didn't press enough/too much.My next step is now to take the board out and check all the connection and re solder what looks bad. I keep posting the results.Thank you duak for the explanation!!Have a great weekend

author: Duesentrieb66
author_rank: Newbie
timestamp: October 20, 2023, 03:20:38 pm
content: to duak: it is a Bridgeport TorqueCut22. love this little machine