Laser Subcommittee Meeting 2018-12-17


  • BlakeS, NickB, KamilS, FletcherB, Lemming
  • G.Weike LC1290/Big Red
DateHour count
  • G.Weike LG500/Little Red
    • No Class 2 red aiming laser
    • Keys dying on control pad - down arrow?
    • Test cut nice and fast, 3mm MDF at over 15 mm/sec
      • 22mA, configured Max-Power still at 67
      • Whiteboard says 9mm/sec? possibly less reliable cuts over the whole honeycomb workspace
      • 2018-12-17 Fletcher tests at 16mm/sec
  • KH-7050/Kellogg
    • Has PC next to it - installed?
      • Software seems to work?
      • Kamil: Laser tube ready to install in the next week?
  • IainG's 25W Shiny Rabbit table top laser cutter visiting for Canning STEAM, Science show @20181208/Little blue
    • Currently borrowing Kellogg's compressor
  • LC1290/Big Red fault finding
    • Laser is cutting very poorly, but displayed current is still OK
      • If the tube is failing; it's our third (second arrived broken) Reci W6, installed 2016-12-28: so it has had about 1000 hours burn time?
      • If the HV PSU is failing; it's our second MYJG-150 (150W), USD$410+shipping, installed 2015-01? A suitable spare will probably be cheaper and we're inclined to get one regardless.
    • Blake: Diagnostics yesterday 2018-12-16
      • Cleaned mirrors, lens
      • Checked alignment - OK
      • No improvement ~20mm/s for 3mm MDF
      • Tried to clean tube end
      • Stopped cutting at all - just marking wood
      • Still drawing 26mA
    • Fault finding today
      • We think could hear electrical arcing while laser running - 26mA
      • Tried taking end cover off and recording video
        • Cannot find actual arcing, possibly OK?
        • STILL TO CHECK: Laser is operational, but is the plasma stable at both ends?
      • Look for arcing of power supply - find nothing
      • Take out power supply: model MYJG-150 (150W)
      • Look through insulation for signs of arcing
        • Maybe arcing at crimp
      • Test outside with dummy load. milli-Ammeter in series and 1000:1 HV probe with multi meter
        • 102 kiloohm resistor (100W)
        • When firing power supply (“Text” = “Test”) button: 44mA, 4400V (193.6W)
        • When connecting two dummy loads in series: 206 kiloohm: 42mA, 8700V (365.4W)
        • The dummy loads do not drive the HV PSU at full power - 29000V (~750W)
          • 130W to 145W output for ~20% power efficiency
  • HV PSU models:
    • Kellogg: BH-80W
    • LG500/Little Red: MYJG-60 (60W)
    • LC1290/Big Red: MYJG-150 (150W)
  • subcommittee/laser-minutes-20181217.txt
  • Last modified: 2020/03/12 12:49
  • (external edit)