KH-7050 Laser dead

Hardware settings, adjustments and fixes and other hardware discussion. This includes the "doHICky" Laser Power measurement system by Russ.
Chris Medcalf
Posts: 41
Joined: Sat Mar 30, 2019
Location: UK
Country: UK why is UK too short?
Nickname: greenwing
Laser Machine Make or Type: KH7050
Laser Power: 60w ish
Laser Bed Size: 700x500
Home Position: TR
RDWorks Version: new
Windows Version: 7.01

It sounds like your estop switch is faulty, or at least not allowing power past it. On my machine, the estop cuts power to everything except the light and the electronics bay fan, which seems to be all you have working. Possibly you have reconnected the switch wrong.
Josh Bern
Posts: 19
Joined: Fri Aug 17, 2018
Location: Florida
Country: United States of America
Nickname: Josh
Laser Machine Make or Type: KH-7050
Laser Power: 100w
Laser Bed Size: 28" x 20"
Home Position: TL
RDWorks Version: v8.01.10
Windows Version: 10
Accessories: CW-3000 Water chiller
Blower for exhaust

So I finally got back to work on the laser.

I’m looking at the e-stop because now I think that may be the problem. I measured the voltage of the two terminals coming out of the e-stop and I get about 110V. I tried to close the switch and it still said 110V. Could that be the problem? Is the switch broken? What other terminals can I test? Thank you!
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Gene Uselman
Posts: 2180
Joined: Thu Jul 07, 2016
Location: Suburban Minneapolis, Minnesota, US
Country: USA
Nickname: Gene
Laser Machine Make or Type: QC
Laser Power: 130W
Laser Bed Size: 900x1300
Home Position: TR
Control Software: LIGHTBURN
RDWorks Version: RDw .19 & Lightburn
LightBurn Version: Latest
Ruida Controller: RDC6442
Windows Version: Win 10 Pro
Accessories: I have a combining lenses, pin tables [homebuilt], honeycomb tables , wireless remote, Modifed Ultimate Air Assist, home built non-powered rotary device, PrusaMK4 and Mini Prusa printers.

Is your laser 110V or 220V? If it is 220v, that might be one leg of the 220. If 110v- yes with the Eswitch not pushed you should get 110 on both terminals.
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Josh Bern
Posts: 19
Joined: Fri Aug 17, 2018
Location: Florida
Country: United States of America
Nickname: Josh
Laser Machine Make or Type: KH-7050
Laser Power: 100w
Laser Bed Size: 28" x 20"
Home Position: TL
RDWorks Version: v8.01.10
Windows Version: 10
Accessories: CW-3000 Water chiller
Blower for exhaust

It is 110V and I'm getting 110 from the e-stop when it is pushed and not pushed. Does that make sense?
Josh Bern
Posts: 19
Joined: Fri Aug 17, 2018
Location: Florida
Country: United States of America
Nickname: Josh
Laser Machine Make or Type: KH-7050
Laser Power: 100w
Laser Bed Size: 28" x 20"
Home Position: TL
RDWorks Version: v8.01.10
Windows Version: 10
Accessories: CW-3000 Water chiller
Blower for exhaust

Alright, I bypassed the e-stop and blew up some alligator clips while doing so but I can confirm that was the problem. Now, where can I order a new switch? What model is it? Thank you! I'm so happy :D

https://photos.app.goo.gl/yDLyXDNVkackLCnSA
Josh Bern
Posts: 19
Joined: Fri Aug 17, 2018
Location: Florida
Country: United States of America
Nickname: Josh
Laser Machine Make or Type: KH-7050
Laser Power: 100w
Laser Bed Size: 28" x 20"
Home Position: TL
RDWorks Version: v8.01.10
Windows Version: 10
Accessories: CW-3000 Water chiller
Blower for exhaust

Also, how can I safely bypass it in the meantime without burning up wires?
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Gene Uselman
Posts: 2180
Joined: Thu Jul 07, 2016
Location: Suburban Minneapolis, Minnesota, US
Country: USA
Nickname: Gene
Laser Machine Make or Type: QC
Laser Power: 130W
Laser Bed Size: 900x1300
Home Position: TR
Control Software: LIGHTBURN
RDWorks Version: RDw .19 & Lightburn
LightBurn Version: Latest
Ruida Controller: RDC6442
Windows Version: Win 10 Pro
Accessories: I have a combining lenses, pin tables [homebuilt], honeycomb tables , wireless remote, Modifed Ultimate Air Assist, home built non-powered rotary device, PrusaMK4 and Mini Prusa printers.

[Safely] attach both wires to one terminal. I am not sure I have ever used an emergency switch on anything. It is kinda like the horn on my car, my sweetie sez 'Honk at that fool' and I don't really know where it is. I guess I am such a slow mover that I don't have emergencies.
If the Help and advice you received here was of VALUE...
Please consider making a donation to maintain the RDWORKSLAB Forum.



The days that I keep my gratitude higher than
my expectations, Well, I have really good days.

Ray Wylie Hubbard- unfortunately deceased
Jeffrey Aley
Posts: 388
Joined: Fri Aug 11, 2017
Location: Folsom, California
Country: United States
Laser Machine Make or Type: Kehui
Laser Power: 50W
Laser Bed Size: 500mmx300mm
Home Position: TL
RDWorks Version: 8.01.24
Ruida Controller: RDC6442
Windows Version: Win10 Enterprise
Accessories: Spray bottle with water (for small fires)
Fire extinguisher (for big fires)

I recommend that you get a friend who is an electrician (or who is very familiar with electricity) to help you.
After turning off the power and unplugging the laser, your friend will need to carefully examine the EMO switch and how it is wired in your machine. For example, is it wired with two NC contacts (one for Line and one for Common), or is it wired with just one NC contact (Line only)?

Once that is determined, your friend can bypass it; use at least 14AWG wire and insulate it properly.

When replacing it, do NOT buy a cheap Chinese EMO switch. This switch is for safety (such as when your laser catches fire - oh yes, it will) so you want to be sure it'll work. Get one from a domestic supplier (Grainger, etc.) that is UL-Listed. The new switch should be rated at 15A or 20A, preferably the latter.

And as I've posted before, never ever use the "convenience" electrical outlets on the back of the machine. (You didn't say that you did, but I thought I'd mention it). Get one of these instead: https://www.amazon.com/Tripp-Lite-Indiv ... 219&sr=8-5

Regards,

-Jeff
Josh Bern
Posts: 19
Joined: Fri Aug 17, 2018
Location: Florida
Country: United States of America
Nickname: Josh
Laser Machine Make or Type: KH-7050
Laser Power: 100w
Laser Bed Size: 28" x 20"
Home Position: TL
RDWorks Version: v8.01.10
Windows Version: 10
Accessories: CW-3000 Water chiller
Blower for exhaust

Thank you for the help. I successfully bypassed the e-stop by connecting the terminals. Everything works now.

Thank you as well for the info on electricity tips. Now I need to find a new switch but my research on Grainger only finds 10A switches.
What about this one?
https://www.amazon.com/HONEYWELL-87943- ... ay&sr=8-12

If you have a good option, please send the link. Thank you so much!
Bryant Prenger
Posts: 5
Joined: Tue May 21, 2019
Location: California, MO
Country: United States
Laser Machine Make or Type: KH-7050
Laser Power: 100w
Laser Bed Size: 700x500
Home Position: TL
RDWorks Version: v8.01.18
Windows Version: 10

Seems as if you got it figured out! Congrats.

Im having the exact same problems you were however mine is dead dead with nothing at all coming on. (same machine too)
Heres what ive done.

1. Changed fuse to known good fuse.

2. Bypassed estop switch with no change.

3. Verified Voltage going to both Laser and 24v Power supplies.

4. Checked fuse in laser power supply -good

Anyone have any ideas?
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