KH-7050 Laser dead

Hardware settings, adjustments and fixes and other hardware discussion. This includes the "doHICky" Laser Power measurement system by Russ.
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

My knowledge is pretty limited but have you checked to see if any breakers have been switched off? My machine doesn't have one but some do.
Apparently the laser power supply tends to die and may need to be replaced. Other than that, I'm not sure.
I wish I could help more.
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

Both the fuses I could find were good. I did order a new 24v power supply. I'm gonna give that a try. I have voltage going into it but not out. I'm not sure that'll do it tho.
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)

Bryant Prenger wrote: Tue May 21, 2019 Both the fuses I could find were good. I did order a new 24v power supply. I'm gonna give that a try. I have voltage going into it but not out. I'm not sure that'll do it tho.
Good job isolating the problem. There's one other thing I'd do: disconnect the wires from the output of the 24V power supply, and then test the output voltage. The reason for doing this: if the outputs are shorted somewhere, then you'll get no voltage out of the supply. By removing the wires, you truly isolate the power supply itself. Thus, if you know there's voltage coming in, and nothing is connected to the output, you can tell if it's the supply (or some component within the supply like a fuse), or if it's actually something downstream of the supply.

For the High-Voltage supply, is there a fan that comes on when it's powered up? Also look for LED lights and a test / pulse button.
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

Jeffrey Aley wrote: Wed May 22, 2019
Bryant Prenger wrote: Tue May 21, 2019 Both the fuses I could find were good. I did order a new 24v power supply. I'm gonna give that a try. I have voltage going into it but not out. I'm not sure that'll do it tho.
Good job isolating the problem. There's one other thing I'd do: disconnect the wires from the output of the 24V power supply, and then test the output voltage. The reason for doing this: if the outputs are shorted somewhere, then you'll get no voltage out of the supply. By removing the wires, you truly isolate the power supply itself. Thus, if you know there's voltage coming in, and nothing is connected to the output, you can tell if it's the supply (or some component within the supply like a fuse), or if it's actually something downstream of the supply.

For the High-Voltage supply, is there a fan that comes on when it's powered up? Also look for LED lights and a test / pulse button.
I'll definitely do that with the 24v. As far as the high voltage power supply goes, I have voltage to it as well but nothing at all happens. It's as if it's not getting a "signal" to turn on. No fans, lights, and the test button do anything.
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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.

Josh Bern wrote: Tue May 21, 2019 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!
Josh- you might want to check the mounting hole size unless you have tools to enlarge the hole in the case. I worked for Honeywell 55 years ago as a technician building and calibrating the guidance and control systems for the Lunar Expeditionary Module. God I am getting old.
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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

So I measured and have a 25mm hole but the emergency stop plate is 22mm. Therefore, I think I need a 22mm one. Size is no longer an issue.
I tried to find a 20A UL certified one but it is very difficult. Also, I need to make sure there are 4 contacts because some only have 2.
Do you have any recommendations? You seem incredibly knowledgeable and experienced :D

https://www.amazon.com/Baomain-Mushroom ... way&sr=8-1 (This one is closest to the original but cheap Chinese and I was not recommended to use a cheap one.)

https://www.grainger.com/product/DAYTON ... ton-30G250 (this might work)

Rather, I was told to use a UL certified reputable switch. https://www.grainger.com/product/HONEYW ... ton-22A627 (This only has to contact points I think)

Please let me know which you recommend. Thank you!
Doug Fisher
Posts: 206
Joined: Sat Aug 20, 2016
Location: Atlanta, Georgia
Country: USA
Laser Machine Make or Type: Ke Hui KH-7050
Laser Power: 80W EFR F2
Laser Bed Size: 700x500
Home Position: TR
Control Software: LIGHTBURN
RDWorks Version: v8.01.18 & 8.01.33
Ruida Controller: RDC6442
Windows Version: 10
Accessories: Ruida RDC6442G EC controller, 2" lens, S&A CW5000 chiller, chuck type of rotary attachment, Russ' DoHickey (sp?), mA meter, a growing collection of tools and oddities to keep it running!

You might look at Cloudray and Lightobject.

Most E-stops fail because people are using the sockets on the back of the machine to power other devices. Do not use those sockets for anything. I think Gene mentioned this before.
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

Yep. The only reason I used the back plug was for my blower which was a Japanese/Chinese plug type. I ordered an adapter and will use a well rated Belkin power strip.

Everything you said makes a lot of sense to me. Thank you!
Doug Fisher
Posts: 206
Joined: Sat Aug 20, 2016
Location: Atlanta, Georgia
Country: USA
Laser Machine Make or Type: Ke Hui KH-7050
Laser Power: 80W EFR F2
Laser Bed Size: 700x500
Home Position: TR
Control Software: LIGHTBURN
RDWorks Version: v8.01.18 & 8.01.33
Ruida Controller: RDC6442
Windows Version: 10
Accessories: Ruida RDC6442G EC controller, 2" lens, S&A CW5000 chiller, chuck type of rotary attachment, Russ' DoHickey (sp?), mA meter, a growing collection of tools and oddities to keep it running!

Yep. The blower is probably the worst thing you can plug into those ports. I think most of the classic gray squirrel cage blowers demand 600 watts.

These lasers have wiring intended for 220 volts. The wiring is just barely adequate for 110 volt systems.
Jacek Kruczynski
Posts: 2
Joined: Tue May 21, 2019
Location: Szczecin
Country: Polska
Nickname: RoughBadger
Laser Machine Make or Type: KH-7050
Laser Power: 80W
Laser Bed Size: 700x500
Home Position: TR
RDWorks Version: v8.1.40
Windows Version: 10
Accessories: standard equipment + rotary attachment, analog miliampmeter, thermometer, speed controller for fume extractor, some extra switches for better control

This happened to me also. But I was lucky, had to replace one fuse in the machine with a spare they provided.

Just in case someone have same issue, here some pictures:
1.jpg
2.jpg
3.jpg
4.jpg
Works fine after replacement ;)
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