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20-622 Steering Voltage Adjustment Procedure

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Overview:

The condenser and objective steering voltages in the 20-622 electron gun control used on the PHI 660 scanning auger systems  need to be adjusted periodically (check it as part of   preventive maintenance service) for optimal image stability.

If your image is stigmatic and moves a lot when you change your objective lens, you may want to check the condenser and objective steering voltages. A small amount of image movement is normal.

Following this procedure will ensure that the steering voltages are operating properly and also that they are properly balanced.

Summary Table:

J3 Pin Description Offset Pot Gain Pot Deflection Bd. Pin Lens Bd. Pin

A

 COND X

R 27

R 25

 Defl 1 pin 8 58
C COND X R 27 R 25 Defl 1 pin 10 58
B COND Y

R 23

R 22

 Defl 1 pin 62 50
D COND Y R 23 R 22 Defl 1 pin 64 50
E OBJ X

R 36

R 35

 Defl II pin 7 66
G OBJ X R36 R 35 Defl II pin 9 66
F OBJ Y

R 34

R 33

 Defl II pin 61 56
H OBJ Y R 34 R 33 Defl II pin 63 56

 

    Procedure:

  1. Turn OFF the 20-610 30kV High Voltage Supply.
  2. Remove the 20-622 from the electronic console and extend the Lens control card (second board from the top). Support the board so that it is level with a non-conductive object. Remove all cables going to the 20-622 except for the power and the 40 pin ribbon cable between the PC147.
  3. Connect a DVM between pins A and C on the J3 COND & OBJ Steering connector on the back of the 20-622.
  4. Turn on the 20-622 and in AugerMap set the Beam voltage to 10kV and also set the COND X steering to 50% (mid-range).
  5. Adjust R 27 on the lens control board for zero volts on the DVM.
  6. Set the COND X steering to 100% and adjust R 25 for 205.0 volts DC.
  7. Connect the DVM between pins B & D on J3.
  8. Set the COND Y steering to 50% and adjust R 23 for zero volts.
  9. Set the COND Y steering to 100% and adjust R 22 for 205.0 volts DC.
  10. Connect the DVM between pins E & G on J3.
  11. Set the OBJ X steering to 50% and adjust R 36 for zero volts.
  12. Set the OBJ X steering to 100% and adjust R 35 for 205.0 volts DC.
  13. Connect the DVM between pins F and H on J3.
  14. Set the OBJ Y steering to 50% and adjust R 34 for zero volts.
  15. Set the OBJ Y steering to 100% and adjust R33 for 205.0 volts DC.
  16. Set the COND X, COND Y, OBJ X and OBJ Y steering to 50%.
  17. Set the Beam Voltage to 3kV.
  18. Check each pin again with respect to the chassis. They should all be zero volts with-in 50 mV DC and be stable. If they are not stable, the 7541 Dacs or 208H opamps on the error control board are usually the problem.

Calibration Complete.

Cond and Obj Steering

20-622 COND and OBJ Steering connector

 

Test procedure for PHI V/F preamplifiers

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Overview:

Most of the older PHI AES systems use a voltage to frequency converter (V/F) to convert the electron multiplier auger signal output from a small current into a frequency so that the computer can count the signal. At the time these systems were designed, this was a more cost effective approach than using a high resolution A/D converter.

This document explains the procedure for testing the following V/F preamplifiers:

PHI 96

PHI 96A

PHI 96B

RBD V/F-4

Equipment needed:

(1) 30meg ohm resistor (or three 10 Meg ohm resistors soldered together)

(2) Clip Leads

(1) Computer with AugerScan

(1) Oscilloscope (optional)

(1) 4 foot BNC to BNC Cable (optional)

(1) 32-100 Multiplier Supply

Note:

The V/F Preamplifiers used on PHI systems convert the current through the electron multiplier into a frequency. The maximum current is negative 500 nA. By using a 30 Meg ohm resistor (with negative 15 volts DC applied = negative 500nA) , the negative 500 nA can be applied to the collector input without the use of a DC current source, and the V/F preamplifier easily tested.

Caution! Refer servicing of electronic units to qualified personnel.

(If this procedure is followed exactly, no high voltage will be applied to the V/F preamplifier)

 Procedure:

  1. Turn the power off on the 32-100 electron multiplier supply.
  2. IMPORTANT! Remove the HV POS IN, HV POS OUT and COL cables from the V/F preamplifier. This will prevent any high voltage from being applied to the preamplifier during testing.
  3. Set the CMA multiplier switch to OFF.
  4. Remove the cover from the V/F preamplifier:

 

preamplifier-96A-top-view

preamplifier-96A-top-view

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  1. Locate the “Collector” (J4) connection:
preamp-j4-collector

preamp-j4-collector

 

 

 

 

 

 

 

 

 

 

  1. “Jumper” a 30 Meg ohm resistor between L2 (floating minus 15 volt supply) and the COL lead (J4):
preamp-96A-col-and-L2

preamp-96A-col-and-L2

 

 

 

 

 

 

 

 

 

 

 

 

  1. Set up AugerScan to acquire a survey in the V/F mode. Make sure that V/F 1 is selected in the hardware properties and that the Auto EMS is not checked in the multiplier properties dialog box. This will force the input into the V/F mode.
  2. Turn on the 32-100 electron multiplier supply. The CMA high voltage switch should be in the OFF position. Setting the CMA voltage switch to OFF will ensure that no high voltage will be applied to the V/F preamplifier during the test. (And the cables are also disconnected)
  3. Acquire the survey and compare the results with the table below.  If you disconnect the test resistor after the survey is about half way through then you should see the counts drop to just a few thousand CPS.

 

You should have approximately the following counts displayed in AugerScan: V/F preamplifier model number Maximum V/F counts per second
PHI 96 100 kHz
PHI 96A 1 mHz
PHI 96B 1 mHz
RBD V/F-4 4 mHz

 OPTIONAL – If you have an oscilloscope you can also look at the frequency output connector of the V/F preamplifier,  Just connect a BNC cable between your oscilloscope and the Frequency output connector of the V/F preamplifier.

If the frequency output is approximately the value shown in the table above, then your preamplifier is working properly. If not, RBD Instruments provides repair services and loaner V/F preamplifiers.

When finished testing, turn off the 32-100 and replace the cables to the V/F preamplifier and set the 32-100 switch to where it was before testing (typically it is set to digital).

BONUS – Here is a link to the 96A Manual, which is the most common V/F preamplifier used on older PHI AES systems.  If you have a 96B or VF4 contact RBD Instruments.

 

11-065 28 Volt supply Check

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The 28 V DC power supply in the PHI 11-065 ion gun control can become weak and cause symptoms such as low emission current. To test the supply, measure the voltage from the red wire to chassis ground. It should be 28 volts to 29 volts DC, with less than 100mV AC ripple. When defective, the DC voltage will be low (about 10 to 16 volts) and there will be high AC ripple (3 to 6 volts).

Measure from the red wire post to the chassis.  CAUTION – refer servicing and testing to qualified personnel.

28-volt-supply-test-point

28-volt-supply-test-point

 

 

If your 11-065 28 volt supply is defective, RBD carries them in stock at all times. Contact us for more information.