Search found 141 matches

by Liam David
Wed Nov 30, 2016 2:51 am
Forum: High Voltage - Fusor Input Power (& FAQs)
Topic: Spellman DXM70N600X3547 power supplies on ebay -70kV 8.56MA
Replies: 157
Views: 64236

Re: Spellman DXM70N600X3547 power supplies on ebay -70kV 8.5

I applied 24V to the fan connector and the digital circuitry came on with a green system power light. This narrows the problem down to the converter. C149 has about 120V across it, diode CR34 is good, and the transformer T2 appears intact. Both secondary coils do have continuity between them, but I ...
by Liam David
Tue Nov 29, 2016 12:20 pm
Forum: High Voltage - Fusor Input Power (& FAQs)
Topic: Spellman DXM70N600X3547 power supplies on ebay -70kV 8.56MA
Replies: 157
Views: 64236

Re: Spellman DXM70N600X3547 power supplies on ebay -70kV 8.5

I replaced the blown IRFBG30 mosfet on my power supply board, but it still does not function. I checked all of the capacitors, and C149 has a slight bulge but has no continuity. Otherwise none of the components on the board appear damaged. Removing the fan revealed that there is only about 2V on the...
by Liam David
Sun Nov 20, 2016 7:26 pm
Forum: High Voltage - Fusor Input Power (& FAQs)
Topic: Spellman DXM70N600X3547 power supplies on ebay -70kV 8.56MA
Replies: 157
Views: 64236

Re: Spellman DXM70N600X3547 power supplies on ebay -70kV 8.5

I have found the failure point in my power supply. A IRFBG30 mosfet blew out on the top board and came right off the board in pieces. I'll be ordering a replacement and will see what happens. I hope it didn't cause a chain of failures, or vise versa. Location of the blowout http://i1186.photobucket....
by Liam David
Sat Nov 19, 2016 8:45 pm
Forum: High Voltage - Fusor Input Power (& FAQs)
Topic: Spellman DXM70N600X3547 power supplies on ebay -70kV 8.56MA
Replies: 157
Views: 64236

Re: Spellman DXM70N600X3547 power supplies on ebay -70kV 8.5

One of mine was also DOA, even though I can hear a humming noise emanating from somewhere. I checked both input fuses and they were fine, and power was going to the board, but nothing. The one that works came on immediately; the Ethernet connector blinked a few times, the fan came on, and the power ...
by Liam David
Sat Nov 19, 2016 2:05 am
Forum: Images du Jour
Topic: Chamber wall rainbows
Replies: 10
Views: 4347

Re: Chamber wall rainbows

Since I have a small 2.75" 6-way chamber, running the grid white-hot for about an hour resulted in the disappearance in the rainbow pattern as the walls turned black. I have looked at the effects of this tungsten "bombardment" on aluminum foil under a SEM, and compared to regular foil, the damage is...
by Liam David
Sun Jul 03, 2016 12:40 pm
Forum: Neutrons, Radiation, and Detection (& FAQs)
Topic: Ludlum Model 3 with He-3 Tube
Replies: 3
Views: 1977

Re: Ludlum Model 3 with He-3 Tube

Sorry, I'll give a few more details. I contacted Ludlum a month ago and they were nice enough to donate a Model 3 with 44-9 probe and Model 26 handheld frisker. Everything is functional and calibrated. The neutron tube seller had a NIM bin setup and provided a video showing the tube's response using...
by Liam David
Sat Jul 02, 2016 2:51 pm
Forum: Neutrons, Radiation, and Detection (& FAQs)
Topic: Ludlum Model 3 with He-3 Tube
Replies: 3
Views: 1977

Ludlum Model 3 with He-3 Tube

I recently acquired a Ludlum Model 3 and a large He-3 tube. The seller said the tube responded well at 1500V, which is the upper end of the Model 3's voltage range, so would the Model 3 work with such a tube? Technically it's not made for proportional tubes and the discrimination can't be adjusted, ...
by Liam David
Sat Apr 09, 2016 12:27 am
Forum: Images du Jour
Topic: Liam David Fusor Update
Replies: 42
Views: 15416

Re: Liam David Fusor Update

The new TCP-040 controller arrived today, and I bolted the chamber together to do a vacuum test. The roughing pump only reached about 350mtorr due to outgassing, but the turbo pump pulled the chamber to 1E-5 torr in just a few minutes. The turbo accelerated fine and has a high, almost piercing pitch...
by Liam David
Wed Dec 16, 2015 10:18 pm
Forum: Images du Jour
Topic: Liam David Fusor Update
Replies: 42
Views: 15416

Re: Liam David Fusor Update

No, they're willing to inspect it for free to see if it's repairable, but one of the (technicians?) emailed me and said it's not.
by Liam David
Wed Dec 16, 2015 8:48 pm
Forum: Images du Jour
Topic: Liam David Fusor Update
Replies: 42
Views: 15416

Re: Liam David Fusor Update

I have contacted a repair company and they say that when the magnet rings are cracked, the pump is irreparable. Is this true? The pump rotor can be disassembled with a spanner wrench, and ultimately everything had to be assembled, including the magnet rings, so...?