Well, that’s bad timing. How dare that machine break now? Why couldn’t it have waited until after my mom’s visit? I wanted to show her how it worked by making something cool for her! (grumble, grumble)
Thanks for the update, LCC. And thanks for your hard work on the laser cutter.
Hi guys, thank you so much for taking care, ordering the parts, investing your time, etc. Feel free to count on me if you need any help. I will be more than glad to offer my time as well. Have a great evening.
I wasn’t able to find a schematic for the power supply while searching online, but I’m still willing to attempt a fix. Am at VHS right now (Wed Mar 1 8:15pm ), so if I get permission from a Laser committee member within an hour or two, I will take a look.
Thanks, will peek around, but won’t actually attempt repairs today. Just a scouting mission for what parts are being used and how, so I can look up some datasheets. If I find anything unusual, I’ll let you all know. BTW, do you know if VHS has a resistor dummy load to take place of the laser tube while testing power supply?
Yes, I have seen a few large wattage resistors and an adjustable 10ohm 50watt potentiometer as well. If you can’t find them pm me and I can meet you at the space.
Also, it’s worth pointing out that the laser’s power supply died a few months ago and it was replaced. I believe the old power supply is in a box labelled power supplies under (or near) the microscope bench. That means you would have two power supplies to play with.
I have some 40KV wire if you need some for testing as well.
Below, bottom of power supply board showing 4 main switching MOSFETS that drive the flybacks. The white residue is normal. It’s thermal compound that helps transfer heat to the outer case :
Below, Top down view of main PS board showing flybacks on the left and the big blue filter capacitors that feed them with DC (rectified) mains power The four black lumps below them are the main bridge rectifier and the LC line filter capacitors and inductor. Below them are two ceramic power fuses (white) and the RF suppression caps (small blue) and control logic wiring connectors (green).
So far, no obvious visual signs of physical damage such as burning, arcing, blown caps or cracked solder joints. Will do more in depth testing at next opportunity. Will any key holders be at VHS tonight? I don’t see any calendar entries for this evening.
I’m an electronics n00b, but A couple of pins (in the daughterboard connectors?) look like they might be bridged (green underlines in image), plus the general dirtiness might be hiding problems.
Presumably very little of the dust will contain conductive materials, but you never know, you know?
Thanks Hector,
I appreciate your offer to open the space. Would some time this afternoon, or this evening, be ok? An hour (or more) advance notice would be best. Am in Burnaby, so it takes about an hour to hop on the skytrain, and walk to VHS.
If we are using a filter box, then we should be using a furnace fan with enough pressure / suction to draw air through the filter. The booster fan I see has high CFU, but low pressure. Is it able to draw air through the filters? I suspect not?