Seig C3 CNC spindle problem

[john swift]

I have not found an exact match but this PDF wiring diagram for a
110V mini lathe gives you a basic wiring diagram
PDF diagram


for the CNC conversion
the speed control potentiometer that is normally connected to terminals p1 to p3 has been replaced by
a DC control voltage connected to p1 & p2



without the circuit diagram of the speed control board
I can not guess what the blue wires are connected to and
what possible damage to the board could of happened to the board



if the under side of the PCB looks OK with no blown tracks
it will be possible to bench test the board using a 100W bulb as a dummy load in place of the motor and a potentiometer connected to P1 to P3
NOTE - all the board & the wiring to the potentiometer will be live !!!

repairing my CL300m lathes speed control board
https://www.model-engineer.co.uk/for...p?th=38809&p=1

John

PS
found it
the board is a XMT-2360

[Leadhead]

John - Thanks, the board is XMT 2360. The two blue wires are connected to the green chuck guard switch you have indicated. There are currently 3.6V across the terminals.

[john swift]

Les has details of the XMT-2360 on his web site
http://lesjhobbies.weebly.com/upload.../pcb_speed.pdf

if your lucky R17 on page 2 has gone high resistance when terminal K3 shorted to earth

terminal K4 shorting to earth will be of a problem

John

[Leadhead]

John - If the R17 has gone high. Is there anything I can do?
Rod

[john swift]

looking at the circuit diagram I linked to

this a simplified diagram of the low voltage supplies to the control circuit



R17 is the large resistor on the board

its value is 15 K (15000 ohms)
in parallel with a 100K resistor that gives you a total of 13K

if you get more than 13K then R17 will need replacing
has R17 changed colour ?



the resistors drops the rectified mains down to 22V at terminal K4 is linked to K3

with K3 & K4 open circuit I would of expected you to have 200V DC

if terminal K4 was shorted to earth
a number of semiconductors will need checking
starting with Z1 the 22V zenner and the 78L12 regulator IC

John

[Leadhead]

The machine in question is in fact my X3 mill and not the C3 lathe.