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Table of Contents
aka Gendex GX-1000, General Electric GE 1000
WARNING WARNING WARNING
X-ray machines can be dangerous if not properly used
WARNING WARNING WARNING
GE 1000 (Gendex 1000) dental x-ray head. My machine was made 1977, Gendex split in 1983
I was told this head was from a GX 700 but I think its actually a GX 1000. This also matches the case markings better. I think the terms “GE 1000” and “GX 1000” are interchangable
Why: got Gendex USB x-ray sensor on surplus market and trying to make a PCB x-ray inspection machine
Markings
dataplate
GENERAL ELECTRIC COMPANY MILWAUKEE WISCONSIN MADE IN USA ------------------------- GE 1000 HOUSING MODEL 46 137660610 MINIMUM FILTRATION 20 MM ALUMINUM EQUIVILENT AT 100 KVP SERIAL 175092 ------------------------- E1 0 TUBE INSERT MODEL 46 12539461 FOCUS 10 MINIMUM FILTRATION 0.5 MM ALUMINUM EQUIVILENT AT 100 KVP SERIAL 42453 ------------------------- COMPLIES WITH DHEW RADIATION PERFORMANCE STANDARDS, 21CFR SUBCHAPTER J TUBE HOUSING ASSEMBLY MANUFACTURERED September 1977 ------------------------- X RAY EQUIPMENT CLASSIFIED BY UNDERWRITERS LABRATORIES INC WITH RESPECT TO FIRE SHOCK AND MECHANICAL HAZARDS ONLY SEE UL CLASSIFIED PRODUCT INDEX 3101 SA
External connections
With best guess at pinout
Side
- A1
- HV primary1
- MA
- Current sense
- Probably very high ohm resistor
- Tie to ground if unused
- P1
- HV primary2
Side
- X
- Fillament primary1
- G
- Ground
- XC
- Fillament primary2
Control box is rated peak of 115 V * 18 A = 2070 W
Resistances
- AI-PI: 0.4 ohm
- High voltage
- “The HV transformer has a ratio of approx 1:700, so you get 1 kV peak on the tube per volt RMS on the input. The effective output impedance of the transformer is around 500 k, leading to a drop in the HV of 500 V per mA of tube current.” [4hv]
- X-XC: 19.2 ohm
- Fillament
- “X-Xc is the filament transformer, don't power it from 115V, normal filament running voltage is usually 50 - 70 V RMS, depending on the tube type inside the head.” [4hv]
- 35% on my small variac (maybe around 40V) was enough to sature my 150,000 CPM rated MyGeiger2 (SBM-20)
- ie no clicks but actually in very high radiation
- hard to measure actual radiation because CPM has long averaging period
- G-case: 0.0 ohm
- Ground
- All others: inf
- MA: current monitoring
- Tie to ground if unused
Above: slip ring on arm. I'm not using this. One of the spring contacts can be barely seen
Tube
The control boxes indicate its a 100 kV, 10 mA (or 90 kV 15 mA) tube. I get the impression this is unusually powerful. I tend to remember someone said this unit is too powerful to use in modern dental offices but should be fine for PCB inspection
46-158800G2 controller
Master control unit. Provides correct voltages to up to three tubeheads
From [eBay 291057383064]
46-181123G1 remote control
Provides remote control, came with my tubehead. The main controller was still in use for a bit longer so wasn't able to take it but might be able to get it in a few months
15 mA and 10 mA scale. Someone mentioned that
46-18109B meter board
- Makes display read 100kVp @ 118 VAC
Tubehead schematic
Above: best guess at schematic
Above: T2, the isolating filament transformer. The bottom lug connectors are actually soldered to T1
Above: T1, the high voltage transformer (HV side). Both sides run at high voltage. The x-ray tube assembly is spring loaded against T1.2
References
- 4hv thread that helped me get it going: http://4hv.org/e107_plugins/forum/forum_viewtopic.php?166075.last
-
- Very useful document with equipment pictures, descriptions, and part numbers from the original system
-
- GX-1000 tubehead teardown
- Has a number of useful comments
-
- Video of someone cutting open what I think is the same model
-
- An x-ray head teardown
- eBay toolsplusmore83: item 291057383064
