On & Off RPM SENSOR or Something Else ??

[Brad Wardman]

Machine does not spin the bit at startup on some occassions. The motor does kick in though, but just hear the hummmmm. Tap on the sensor, wiggle some wires and then it will run for a bit. Then, while cutting, spindle will surge in speed, then stop. Do the process over and it will start back up. ny ideas ??

Motor has been removed & cleaned, shaft is good, etc. Also checked the cap on the x term board. About 400 hours on a C machine. Motor brushes have been changed. We are very "mechanical" so I think we have tried all the normal stuff.
Could this be the RPS sensor or is something else going on ?? need a new motor ??

If it is the RPM...anyone have one that I can buy w/o the $12 shipping charge ??

Brad

[Digitalwoodshop]

Sounds like a bad cut motor.... A Open or Shorted wire in the Armature or Stator... The Copper Wire in the motor is covered with a coating that insulates the wires as they are wound on each other... IF 2 wires get the insulation damaged they could short together. So what was once a 100 turn coil of wire could become a 20 turn as the 2 wires bypassed the 80 other turns and electricity takes the path of least resistance.... I am only basing this on the HUMMING... There are some times when the cut motor will change speed most likely while doing V Text. But changing speed and then stopping is a BIG PROBLEM.... It could result in a FIRE....


The other thing could be the Q1 Transistor on the X Termination Board and even the Photo Couplers that convert the computer command to light as in a LED to the Photo Detector inside the Photo Coupler that isolates to the Q1 Transistor and turns on the Cut Motor.


Also the Wires going to the Cut Motor... Some have had to RE CRIMP the wire to the connectors as they were loose....


I don't think the RPM sensor has anything to do with this... It monitors the speed.... YOU can check it for operation using Sensor data and rotating the Chuck and with every revolution of the chuck the magnet passes the sensor and counts 0001, 0002, 0003...


You can even un plug the speed sensor and most likely get a CCM Check Cut Motor error but the Motor would still run...


Bad Motor

Bad X Termination Board

Bad Crimp on a Wire


Good Luck,


AL

Edit: One last thing.... IF you have your machine in a UN HEATED Shop and Heat it up to run the machine, CONDENSATION, FROST inside the machine and Computer could be causing the problem.... Water Conducts Electricity.

[henry1]

have to agree with Al do a check

[Brad Wardman]

RPM sensor meters fine, wires & connectionals all good. Motor seems to run fine at full speed when connected directly to a power source. The motor has been doing this a while, but once we get her going, will cut fine for hours. Still possible that the motor is bad or has a short ?? Is the X Termination board a common problem ?? Everything on it is tight and nothing looks burnt or melted.

Brad

[badbert]

when you are powering direct, you are eliminating the connection. Try re-crimping the connectors. Just a little squeeze!

[Brad Wardman]

UPDATE...HELP !!
I know at this point that the X-termination board is bad. Upon removal, the board looked burnt and testing showed that three of the resistors were bad...maybe other things, but I only know how to test resistors with my little meter.
Testing the motor independantly on a power supply, it seems to run just fine.

MY QUESTION....
Do I replace the board OR the board AND the motor ?? I don't want to get a new board & burn it out, but dont want to spend $$ for a motor if not needed. If the motor is running fine could there still be a problem there that is burning out the board or ??

Thanks,
Brad

[chief2007]

UPDATE...HELP !!
I know at this point that the X-termination board is bad. Upon removal, the board looked burnt and testing showed that three of the resistors were bad...maybe other things, but I only know how to test resistors with my little meter.
Testing the motor independantly on a power supply, it seems to run just fine.

MY QUESTION....
Do I replace the board OR the board AND the motor ?? I don't want to get a new board & burn it out, but dont want to spend $$ for a motor if not needed. If the motor is running fine could there still be a problem there that is burning out the board or ??

Thanks,
Brad

Just the board, but I would check the cut motor brushes and maybe change those as well

[Digitalwoodshop]

IF you can, post a close up picture of the Board. Here is one from a few years ago from someone else....

Lets talk about Dust Collection.... Any chance that you had a un grounded dust collector hooked to your machine that causes the board to burn due to a build up of Static Electricity. The Reason I ask is because a Burn Up X Termination Circuit Board is a VERY Un Usual problem and I want to understand....


OR did you use your machine is a Cold Shop with High Humidity as in that Cold SWEAT you see on Tools when you warm a Cold Shop?


OR did you ever have the Cut Motor Wires PINCH with the Cooling Fins of the Z Motor when the wires were not tucked into the corner.... Not a likely cause but I wanted to ask since the motor would normally NOT be powered up when at the Bit Plate Area.


OR do you use a Vacuum Cleaner Hose to clean the Chips out of the machine and caused a Static Discharge?


I would replace just the X Termination board.

The Picture is from 01/31/2011 from someone HERE so you could find the Whole Post about that time... And interesting it is the end of January ALSO..... Could be COLD HUMIDITY and HIGH VOLTAGE as in 115 VAC Arcing....

AL

[Brad Wardman]

Ok....
-Dust collection IS grounded...metal duct AND ground wire.
-Shop is fully temp controlled, kept around 70.
-We are always supervising when running the machine..work on the computer right next to it...and have never had a problem until this recent issue.
-Nothing pinched, worn, broken or otherwise "fishy" looking.
-We use a ringneck head and can brush out anything that isnt picked up by that.
- Machine has around 450 hours and we have done the forum listed recommended maintenance, brushes, etc.

As for the board, once it was out in the light, you could see visible browning & board scorch around the 2 large resistors and capacitor. Upon testing, none of the (3) resistors had any continuity. I cleaned it up and changed the bad resistors & cap (with the proper replacements- I build guitar amps & pedals, so had the stuff handy) but, did not improve the function of the machine. So, I figure probably a bad transistor or something else ??

I ordered a board....Will give that a try. But will gladly take more ideas, advice if someone has something !!

Thanks,
Brad

[Digitalwoodshop]

X Termination Board components:

U1 is a Triac Output .72 cents. http://www.digikey.com/product-detai...011M-ND/284881

U2 is a full wave rectifier .45 cents http://www.digikey.com/product-detai...F04M-ND/965265

U3 is another Transistor Output Opto Coupler .61 cents http://www.digikey.com/product-detai...3VS-ND/1738521

Q1 is a Triac Transistor that turns on the Cut Motor. $1.64 http://www.digikey.com/product-detai...DGOS-ND/918544

You should check my work before ordering any parts. It is easy to mistake a MAC16D and a MAC18D...

I would replace the C1 Cap too for anyone rebuilding one of the boards. And I would use IC Sockets....

I have one with a bad Op Amp, I should fix it someday....

Good JOB on the Resistors and with that list of questions and all the proper Grounding and using a Ringneck Blue Metal Collector.

AL