need help diagnosing Sieg SX3 problem

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fenichel
Posts: 38
Joined: Wed Aug 12, 2009 5:11 pm
Location: West Vancouver, BC

need help diagnosing Sieg SX3 problem

Post by fenichel »

I have a Sieg SX3 mill (= Grizzly G0619, but not from Grizzly) that has suddenly stopped working. Today, in between uneventful uses of the mill, the motor stopped responding to the controls. With the main power on and the emergency stop button out, the mill looks ready: the power lamp is on, and the tachometer shows 0 RPM. The Start button gets no response.
  • The chip-guard safety switch is not likely to be implicated, because I removed this switch long ago. Conceivably, vibration has shorted part of what remains of this circuit; I could rule this out if I knew where this circuit shows up on the XMT daughterboard.
  • I can easily turn the spindle by hand.
  • The fuse (Sieg part #220-4A) on the inverter board is intact.
  • There are no obvious burnt components, bulging electrolytic capacitors, or other signs of electronic failure on the inverter board or its XMT daughterboard.
  • Measured from either side of the #220-4A fuse, the AC voltages on the shielded connector at the right side of the inverter board are
    • 121 at N1 and PE
    • 0 at L1
    • 86.2 at W
    • 86.1 at V
    • 85.5 at U
  • Measured from GND, the DC voltages on the connector at the bottom of the inverter board are
    • 90 mV at S1
    • 1.53 V (varying by 100 mV or so) at K3 and K4
    • 5.04 V at +5V, SB, and SC
    • 30 mV at SA
I suppose that the problem is either with the motor or with one of the PCBs, but I don't know how to localize the problem any more closely. Is there anyone on this forum with access to a working SX3 who would be willing to use a multimeter to give me some standards for comparison?
jcfx
Posts: 713
Joined: Sun Aug 09, 2009 1:24 pm
Location: NY

Re: need help diagnosing Sieg SX3 problem

Post by jcfx »

Did you check the switches, it might be the emergency stop button or start switch ?
That's usually where I look first to see if something may have come loose
or that the switch just failed before looking any deeper.
fenichel
Posts: 38
Joined: Wed Aug 12, 2009 5:11 pm
Location: West Vancouver, BC

Re: need help diagnosing Sieg SX3 problem

Post by fenichel »

It can't be the emergency stop switch, because if that switch were effectively closed (that is, if the button were effectively pushed in), the tachometer would be blank. I can't rule out the start switch having failed; my next step will be to take the front housing off to check, but my check would be more definitive if I knew more about the signals in the multiconductor cable that runs between the Control Panel Circuit Board and the XMT_Control board.
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