Thermo Fisher Technical Support KnowledgeBase record Walton-3F13B Printed to PDF 10/30/2009

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Ion Gauge Troubleshooting for LCQ and Deca Series Introduction:

This document is designed to be used by the instrument user to determine whether the Ion Gauge has failed and user correctable or instead will a service call be needed. Electronic Technician steps are included in case such personnel are available locally.

Observations: A. The Ion Gauge pressure reads 0. B. The Ion Gauge is not lit. (Will not turn on or stay on.) C. The Convectron Gauge reads a normal; pressure D. The Turbo is at full speed.

User level troubleshooting: 1. Outgas. If this is a new Ion Gauge or one that has been vented for a long time then outgas it. A new or gassy

Ion Gauge may need to be outgassed. Try turning on the Ion Gauge several times. If it stays on a little longer with each iteration then gassiness is indicated. Keep trying. Each time the Ion Gauge is turned on you will see the pressure begin to rise until it hits the cutoff at 10e-5. This is the Ion Gauge heating up from the filament heat and driving gas off of the glass walls. Eventually the pressure will rise but level off below 10e-5 and start back down without knocking out the gauge. Don't give up until you have tried 15 times.

2. Replace. Replace the Ion Gauge out of hand if you have one. See our KnowledgeBase record Mahn-56F72 for the details.

Electronic Technician level troubleshooting: 3. Turn off the LCQ Electronics at the Service Mode switch. 4. Remove the top cover to expose the Ion Gauge and cable. 5. ‘Ring out’ the ion gauge.

a. Remove the blue connector from the top of the ion gauge b. Probe pairs of conductors on the ion gauge itself so that you have measured and noted the resistance

between each pair. See figure 1.

29

34 2 + 4: Filament

3: Grid

9: Collector

Figure 1. Ion Gauge pins and functions. The pair 2 to 4 should read a short (<10ohms). If that pair reads open then the filament has broken, the ion gauge will need to be replaced, and that might be all that is wrong. All other pairs should read open (>1Mohm). Any shorts to the filament indicate the filament is warped, the ion gauge will need to be replaced, and that might be all that is wrong. For those two conditions replace the ion gauge.

c. Restore the blue connector to the ion gauge. 6. Remove the right side cover to uncover the System Control pcb. Confirm the electronics are turned off at the

Service Mode switch. 7. Check the F1 and F2 fuses on the system PCB.

a. Remove the fuses from the System Control pcb. b. Measure and note their resistance.

Thermo Fisher Technical Support KnowledgeBase record Walton-3F13B Printed to PDF 10/30/2009

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8. Ring out the Ion Gauge cable connected to the Ion Gauge. Ref: figure 2 a. Disconnect the cable from P9 on the system control pcb. b. Probe pairs of pins in the removed cable end (not P9) to confirm the filament is integral and all the

other pins that go to the ion gauge are open circuit. See figure 2 and Table 1

Figure 2. Plug P9 on the system Control pcb

IG Element:

IG Pin:

Signal Name:

P9 Pin

Collector 9 COLL 1 Filament 2 FIL1 3 Filament 4 FIL2 4 Grid 3 +180 5

Table 1. Signal paths Your work can be restricted to the signals in table 1 even though the cable also carries other signals. If your observations in step 5b above were the expected ones but the same signals measured here are different then this indicates a short or open in the cable.

9. Manipulation of the interlock bypass jumpers. Discussion: Jumpers on the system board can be used to get the system running despite an ion gauge failure. E3 Convectron Gauge Interlock. Located in the High Voltage area on the left side of the system PCB. Normally jumpered "ON". With this setting, the vacuum interlock logic is activated if the convectron pressure is low enough. Also the ion gauge is inhibited from operating. For test purposes, you can set E3 to the "OFF" position to disable this interlock. E5 External Interlock. Located above the LEDs on the bottom right area of the system PCB. Normally jumpered "ON". With this setting, the vacuum interlock logic is activated if the probe head (ESI or APCI) is pulled back from the spray shield. For test purposes, you can set E5 to the "OFF" position to disable this interlock. E6 Vacuum Interlock. Located above the LEDs on the bottom right area of the system PCB. Normally jumpered "ON". With this setting, the vacuum interlock logic is activated if any of the interlocks are tripped. For test purposes, you can set E6 to the "OFF" position to disable this interlock. E7 Ion Gauge Interlock. Located above the LEDs on the bottom right area of the system PCB. Normally jumpered "ON". With this setting, the vacuum interlock logic is activated if the ion gauge pressure is not low enough. For test purposes, you can set E7 to the "OFF" position to disable this interlock.

10. Move all 3 bypass jumpers on the system PCB. Then move them back one at a time. See which one disables the ion gauge.

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