Mini-Convectron Module with Differential Output Amplifier...This instruction manual is for use with...

Mini-Convectron® Module with Differential Output Amplifier

Instruction Manual

Instruction manual part number 275831Revision E - March 2020

Series 275

Mini-Convectron® Module with Differential Amplifier Output

Series 275

Instruction Manual© 2020 MKS Instruments, Inc. All rights reserved.

Granville-Phillips® and Convectron® are registered trademarks, and mksinstTM is a trademark of MKS Instruments, Inc. All other trademarks and registered trademarks are the properties of their respective owners.

Customer Service / Technical Support:

MKS Global Headquarters2 Tech Drive, Suite 201Andover MA, 01810 USAPhone: +1-833-986-1686Email: [email protected] Visit our website at www.mksinst.com

This instruction manual is for use with catalog numbers 275821 & (20)275570-GQ-T.

Mini-Convectron Module with Differential Output Amplifier 5Instruction Manual - 275831

Table of Contents

Chapter 1 Safety and Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71.1 Safety Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71.2 Reading and Following Instructions . . . . . . . . . . . . . . . . . . 81.3 Explosion / Implosion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91.4 System Grounding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111.5 Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111.6 Service Guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111.7 Receiving Inspection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Domestic Shipments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12International Shipments . . . . . . . . . . . . . . . . . . . . . . . . . . . 12Damaged Material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

1.8 Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Chapter 2 Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152.1 Important Precautions for Mini-Convectron Installation . . . 152.2 Mounting Location and Orientation . . . . . . . . . . . . . . . . . . 16

Location . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17Environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

2.3 Grounding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 172.4 Dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 182.5 I/O Connector Wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Chapter 3 Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193.1 Theory of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193.2 Front Panel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203.3 Differential Analog Output . . . . . . . . . . . . . . . . . . . . . . . . . 203.4 Use with Gases other than N2 and Air . . . . . . . . . . . . . . . . . 23

Chapter 4 Service/Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 314.1 General Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 314.2 Mini-Convectron Disassembly . . . . . . . . . . . . . . . . . . . . . . 314.3 Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 324.4 Convectron Gauge Bakeout Instructions . . . . . . . . . . . . . . . 334.5 Cleaning a Convectron Gauge . . . . . . . . . . . . . . . . . . . . . . 334.6 Returning a Mini-Convectron Module for Service . . . . . . . . 34

6 Mini-Convectron Module with Differential Output AmplifierInstruction Manual - 275831


Chapter 1 Safety and Introduction

1.1 Safety Introduction START BY READING THESE IMPORTANT SAFETY INSTRUCTIONS AND NOTES collected here for your convenience and repeated with additional information at appropriate points in these instructions.

NOTE: These instructions do not and cannot provide for every contingency that may arise in connection with the installation, operation, or maintenance of this product. If you require further assistance, contact MKS.

This product was designed and tested to offer reasonably safe service provided it is installed, operated, and serviced in strict accordance with these safety instructions.

In these instructions the word “product” refers to the Mini-Convectron Module and all of its approved parts and accessories.

The instructions in this User Manual explain how to install, operate, and maintain the Mini-Convectron® vacuum gauge module.

• This chapter explains the caution and warning statements used throughout the manual which must be adhered to at all times, your responsibility to read and follow all instructions, how to contact customer service, and product specifications.

• Chapter 2 explains how to install and connect the module.

• Chapter 3 explains the theory of operation, how to operate the module,

These safety alert symbols in this manual or on the Product rear panel, mean caution − personal safety, property damage or danger from electric shock. Read these instructions carefully.

Failure to comply with these instructions may result in serious personal injury, including death, or property damage.

Table 1-1 Terms Describing the Mini-Convectron Module and Components

Term Description

Module The Mini-Convectron vacuum gauge module, which contains a Convectron convection-enhanced Pirani heat-loss pressure gauge.

Convectron Gauge The Convectron convection-enhanced Pirani heat-loss gauge, which measures pressure within the vacuum chamber.

Chapter 1


and using the module with gases other than N2 or Air.

• Chapter 4 explains troubleshooting, Convectron gauge testing, removal and replacement, and module return-for-repair procedures.

1.2 Reading and Following Instructions

You must comply with all instructions while you are installing, operating, or maintaining the module. Failure to comply with the instructions violates standards of design, manufacture, and intended use of the module. MKS Instruments, Inc. disclaims all liability for the customer's failure to comply with the instructions.

• Read instructions – Read all instructions before installing or operating the product.

• Follow instructions – Follow all installation, operating and maintenance instructions.

• Retain instructions – Retain the instructions for future reference.

• Heed warnings and cautions – Adhere to all warnings and caution statements on the product and in these instructions.

Parts and accessories – Install only those replacement parts and accessories that are recommended by MKS. Substitution of parts is hazardous.

Caution and warning statements comply with American Institute of Standards Z535.1–2002 through Z535.5–2002, which set forth voluntary

CAUTIONCaution statements alert you to hazards or unsafe practices that could result in minor personal injury or property damage.Each caution statement explains what you must do to prevent or avoid the potential result of the specified hazard or unsafe practice.

WARNINGWarning statements alert you to hazards or unsafe practices that could result in severe property damage or personal injury due to electrical shock, fire, or explosion.

Each warning statement explains what you must do to prevent or avoid the potential result of the specified hazard or unsafe practice.

Safety and Introduction


practices regarding the content and appearance of safety signs, symbols, and labels.

Each caution or warning statement explains:

a. The specific hazard that you must prevent or unsafe practice that you must avoid,

b. The potential result of your failure to prevent the specified hazard or avoid the unsafe practice, and

c. What you must do to prevent the specified hazardous result.

1.3 Explosion / Implosion

WARNINGThe fumes from solvents such as trichloroethylene, perchloroethylene, toluene, and acetone can be dangerous to health if inhaled. Use only in well ventilated areas exhausted to the outdoors. Acetone and toluene are highly flammable and should not be used near an open flame or energized electrical equipment.

WARNINGIf used improperly, Mini−Convectron Gauges can supply misleading pressure indications that can result in dangerous overpressure conditions within the system.Do not operate in an explosive atmosphere.Do not operate the product in the presence of flammable gases or fumes. Operation of any electrical instrument in such an environment constitutes a definite safety hazard. Do not use the product to measure the pressure of explosive or combustible gases or gas mixtures. The sensor wire of the Mini−Convectron Gauge normally operates at only 125 ˚C, but it is possible that Controller malfunction can raise the sensor temperature above the ignition temperature of combustible mixtures. Danger of explosion or inadvertent venting to atmosphere exists on all vacuum systems which incorporate gas sources or involve processes capable of pressurizing the system above safe limits.

Chapter 1


Danger of injury to personnel and damage to equipment exists on all vacuum systems that incorporate gas sources or involve processes capable of pressuring the system above the limits it can safely withstand.

For example, danger of explosion in a vacuum system exists during backfilling from pressurized gas cylinders because many vacuum devices such as ionization gauge tubes, glass windows, glass belljars, etc., are not designed to be pressurized.

Series 275 instruments are furnished calibrated for N2. They also measure the pressure of air correctly within the accuracy of the instrument. Do not attempt to use a Series 275 Gauge calibrated for N2 to measure or control the pressure of other gases such as argon or CO2, unless accurate conversion data for N2 to the other gas is properly used. See Use with Gases other than N2 and Air on page-23.

A pressure relief valve should be installed in the system if the possibility of exceeding 1000 Torr (1333 mbar) exists.

Suppliers of pressure relief valves and pressure relief disks can be located via an online search. Confirm that these safety devices are properly installed before installing the product.

In addition, check that (1) the proper gas cylinders are installed, (2) gas cylinder valve positions are correct on manual systems, and (3) the automation is correct on automated systems.

WARNINGIf accurate conversion data is not used, or is improperly used, a potential overpressure explosion hazard can be created under certain conditions. Using the N2 calibration to pressurize a vacuum system above about 1 Torr with certain other gases can cause dangerously high pressures which may cause explosion of the system. See the Chapter 4 before using with other gases.



1.4 System Grounding Grounding, though simple, is very important! Be certain that ground circuits are correctly used on your ion gauge power supplies, gauges, and vacuum chambers, regardless of their manufacturer. Safe operation of vacuum equipment, including the Mini-Convectron Module, requires grounding of all exposed conductors of the gauges, the controller and the vacuum system. Lethal Voltages may be established under some operating conditions unless correct grounding is provided.

Ion producing equipment, such as ionization gauges, mass spectrometers, sputtering systems, etc., from many manufacturers may, under some conditions, provide sufficient electrical conduction via a plasma to couple a high voltage electrode potential to the vacuum chamber. If exposed conductive parts of the gauge, controller, and chamber are not properly grounded, they may attain a potential near that of the high voltage electrode during this coupling. Potential fatal electrical shock could then occur because of the high voltage between these exposed conductors and ground.

1.5 Operation It is the installer's responsibility to ensure that the automatic signals provided by the process control module are always used in a safe manner.

Carefully check manual operation of the system and the setpoint programming before switching to automatic operation. Where an equipment malfunction could cause a hazardous situation, always provide for fail-safe operation. As an example, in an automatic backfill operation where a malfunction might cause high internal pressures, provide an appropriate pressure relief device.

1.6 Service Guidelines Some minor problems are readily corrected on site. If the product requires service, contact the MKS Technical Support Department at +1-833-986-1686. If the product must be returned to the factory for service, request a Return Material Authorization (RMA) from MKS. Do not return products without first obtaining an RMA. In some cases a hazardous materials disclosure form may be required. The MKS Customer Service Representative will advise you if the hazardous materials document is required.

When returning products to MKS, be sure to package the products to prevent shipping damage. Shipping damage on returned products as a result of inadequate packaging is the Buyer's responsibility.

For Customer Service / Technical Support:


Chapter 1


1.7 Receiving Inspection

Domestic Shipments Inspect all material received for shipping damage.

Confirm that the shipment includes all material and options ordered. If materials are missing or damaged, the carrier that made the delivery must be notified within 15 days of delivery in accordance with Interstate Commerce regulations to file a valid claim with the carrier. Any damaged material including all containers and packing should be held for carrier inspection. Contact MKS Customer Service if the shipment is not correct for reasons other than shipping damage.

International Shipments

Inspect all material received for shipping damage. Confirm that the shipment includes all material and options ordered. If items are missing or damaged the carrier making delivery to the customs broker must be notified within 15 days of delivery.

If an airfreight forwarder handles the shipment and their agent delivers the shipment to customs the claim must be filed with the airfreight forwarder.

If an airfreight forwarder delivers the shipment to a specific airline and the airline delivers the shipment to customs the claim must be filed with the airline, not the freight forwarder.

Damaged Material Any damaged material, including all containers and packaging, should be held for carrier inspection. Contact MKS Customer Service if the shipment is not correct for reasons other than shipping damage.



1.8 Specifications

Pressure Measurement

Measurement Range for Air or N2 1 mTorr to 760 TorrMeasurements will change with different gases and mixtures. Do not use the module with flammable or explosive gases. The module is factory calibrated for use with Air or N2. It measures the pressure of air correctly within the specified accuracy of the instrument. If the module will measure the pressure of a gas other than Air or N2, you must calibrate the Mini-Convectron Module for the process gas. See Use with Gases other than N2 and Air in the Calibration Chapter.

Temperature Limits

Operating Temperature +4 to +50 °C (+32 to +104 °F) ambient, non-condensing

Non-operating Temperature –40 to +70 °C (–40 to +158 °F)

Bakeout Temperature Range +85 °C maximum with electronics attached

+150 °C maximum with electronics removed

Power Requirements and Electrical Connections

Power Requirement 11.0 to 16.0 Vdc, 0.12 AMust be protected against reversals, transients, or over-voltages.

I/O Connector 9-pin D type

Mini-Convectron Gauge

Sensing Wire Filament Gold-plated tungsten (standard) or solid platinum (optional)

Internal Volume 40 cc (2.5 cu in)

Materials Exposed to Vacuum 304 stainless steel, gold, borosilicate glass, kovar, alumina, NiFe alloy, polyimide

Analog Interface

Differential Output Voltage 0.578 Vdc to 9.963 Vdc nonlinear corresponding to 0 to 760 Torr for N2


Notes:


Chapter 2 Installation

2.1 Important Precautions for Mini-Convectron Installation

The following precautions in the use and installation of the Mini-Convectron must be observed.

• It is recommended that the Mini-Convectron be installed with the port oriented vertically downward to ensure that no system condensates or other liquids collect in the gauge tube. The gauge tube axis must be horizontal if it is to be used at pressures above 1 Torr. Although the gauge tube will read correctly below 1 Torr when mounted in any position, erroneous readings will result at pressures above 1 Torr if the tube axis is not horizontal.

• Do not use a compression mount (quick connect) for attaching the Mini-Convectron to the system in applications resulting in positive pressures in the gauge tube. Positive pressures might blow the tube out of a compression fitting and damage equipment and injure personnel. Pipe thread or flange mounting systems should be used for positive pressure applications. In any case, the absolute pressure in the Convectron gauge tube should not exceed 1000 Torr.

• Do not mount the Mini-Convectron so that deposition of process vapors, upon the internal surfaces of the gauge tube, may occur through line-of-sight access to the interior of the gauge tube.

• Do not install the Mini-Convectron where high amplitudes of vibration are present. Excessive vibration will cause forced convection at high pressure giving erroneous readings.

• Do not install the gauge tubes where they will be subject to corrosive gases such as mercury vapor or fluorine which will attack the gold plated sensor.

• For greatest accuracy and repeatability the Mini-Convectron Module should be located in a stable room temperature environment.

• All connections to the Mini-Convectron Module are to be made with shielded cable. The shield or shields are to be connected to the connector shell.

Chapter 2


2.2 Mounting Location and Orientation

• Cleanliness pays. Keep the port cover in place until just before installation.

• For proper operation above about 1 Torr, install Mini-Convectron Modules with the gauge axis horizontal (see Figure 2-1). Although the gauge will read correctly below 1 Torr when mounted in any position, erroneous readings will result at pressures above 1 Torr if the gauge axis is not horizontal.

• Vibration causes convection cooling of the sensor and will result in high pressure readings. Mount Mini-Convectron Modules where they will not vibrate excessively.

• Orient the gauge to prevent condensation of process vapors on the internal surfaces through line-of-sight access to its interior. If vapor condensation is likely, orient the port downward to help liquids drain out.

Figure 2-1 Mini-Convectron Module Installation

Installation


Location Where you mount the Mini-Convectron Module is critical to obtaining reliable pressure measurements. Long tubing or other constrictions can cause large errors in pressure readings. If you mount the gauge near the pump, the pressure in the gauge may be considerably lower than in the rest of the system. If you place the gauge near a gas inlet or other source of contamination, the pressure in the gauge may be much higher than in the rest of the system.

Environment To minimize temperature effects, locate pressure gauges away from internal and external heat sources, in an area where the ambient temperature is reasonably constant.

2.3 Grounding

Under certain conditions, dangerously high voltage can be conducted through a gas directly to an ungrounded conductor almost as effectively as through a copper wire. The ability of an electric current to flow through a gas under certain circumstances poses a serious risk. Do not touch the exposed pins on any gauge installed on a vacuum system when high voltage is present.

The Convectron Gauge envelope may not be reliably grounded through its vacuum connection. For safety, you must either add a separate ground wire, or shield the envelope to prevent human contact.

Ground the gauge envelope by using a metal hose clamp on the gauge connected by a #12 AWG (minimum size) copper wire to the grounded vacuum chamber.

Figure 2-2 Grounding the Mini-Convectron Gauge

When high voltage is present, all exposed conductors of a vacuum must be maintained at earth ground.

#12 AWG copper wire

Chapter 2


2.4 Dimensions

Figure 2-3 Mini-Convectron Module Physical Dimensions

2.5 I/O Connector Wiring The 9-pin D type connector has the pin assignments shown below.

Figure 2-4 Power and I/O Connector

CAUTIONDo not connect or disconnect any electrical connectors while power is applied to the equipment (hot swapping). Doing so may cause damage to the equipment or severe electrical shock to personnel.


Chapter 3 Operation

3.1 Theory of Operation The module measures gas pressures from 1 mTorr to 760 Torr. Vacuum chamber pressure is measured by a Convectron convection-enhanced Pirani heat-loss gauge.

The Convectron gauge operates like a standard Pirani gauge, which employs the principle of a Wheatstone bridge to convert pressure to voltage, but uses convection cooling to enable accurate pressure measurement, when properly calibrated, from 1 mTorr to 760 Torr.

The sensing wire is an ultra-fine strand of gold-plated tungsten or solid platinum. The heated sensing wire loses more heat as the ambient gas pressure increases. The more molecules contact the sensing wire, the more power is required to keep the sensing wire at a constant temperature. So, as pressure increases, the voltage across the Wheatstone bridge also increases.

The Convectron gauge has a temperature compensator, which causes bridge voltage to remain unaffected by changes in ambient temperature.

Figure 3-1 is a diagram of the module controller. The Convectron gauge sensing wire is designated R1 in the Wheatstone bridge circuit. The temperature compensator is designated R2. At bridge null, the following equation applies:

Bridge voltage is a non-linear function of pressure. This relationship is illustrated in Figure 3-1. If the ambient temperature does not change, R1 remains constant.

Figure 3-1 Wheatstone Bridge Diagram

R1R2 R3+

R4--------------------=

Chapter 3


As vacuum chamber pressure decreases, the number of molecules in the vacuum chamber and the resulting heat loss from the sensing wire also decrease. Temperature and R1 resistance therefore increase.

The increased resistance through R1 causes the bridge to become unbalanced and a voltage to develop across the null terminals. The bridge controller senses the null voltage and decreases the voltage across the bridge until the null voltage again equals zero. When the bridge voltage decreases, the power dissipation in the sensing wire decreases, causing R1 resistance to decrease to its previous value.

A pressure increase causes an opposing series of occurrences, during which the bridge controller increases the bridge voltage to maintain a zero null voltage.

3.2 Front Panel

3.3 Differential Analog Output

Figures 3-2 and 3-3 illustrate the differential analog output voltage for N2/Air. The output is 0.578 Vdc at vacuum, and 9.963 Vdc at 760 Torr for N2/Air. If the output drops to ~0.20 Vdc, there is likely an open sensor in the gauge. If it drops to 0.0 Vdc, the input power (11 to 16 Vdc) has been interrupted.

Table 3-1 Front Panel Features

Front panel feature Function

P > 100 mTorr Indicator A red light emitting diode is used as a rough pressure indicator. The LED will be OFF below 100 milliTorr and gradually turn ON as pressure increases.

Operation


Figure 3-2 Differential Output Voltage vs. Pressure

Chapter 3


Figure 3-3 Differential Output Voltage vs. Pressure

Operation


3.4 Use with Gases other than N2 and Air

Each Mini-Convectron gauge tube is individually calibrated for N2 and temperature compensated prior to leaving the factory.

It is important to understand that the indicated pressure on a Mini-Convectron gauge depends on the type of gas in the tube, and on the orientation of the tube axis as well as on the gas pressure in the tube. Mini-Convectron gauges are supplied calibrated for N2 within the accuracy of the instrument. With certain safety precautions, the Mini-Convectron gauge may be used to measure pressure of other gases.

Mini-Convectron gauge tubes are thermal conductivity gauges of the Pirani type. These gauges transduce gas pressure by measuring the heat loss from a heated sensor wire maintained at constant temperature. For gases other than N2 and air the heat loss is different at any given true pressure and thus the indicated reading will be different.

Figures 3-4 through 3-9 show the true pressure vs. indicated pressure for eleven commonly used gases. The following list will help to locate the proper graph:

A useful interpretation of these curves is, for example, that at a true pressure of 2 x 10–2 Torr of CH4 the heat loss from the sensor is the same as at a pressure of 3 x 10–2 Torr of N2 (see Figure 3-4). The curves at higher pressure vary widely from gas to gas because the thermal losses at higher pressures are greatly different for different gases.

The Mini-Convectron gauge tube uses convection cooling to provide resolution superior to any other thermal conductivity gauge near atmospheric pressure of N2 and air. Because convection effects are geometry dependent, the true pressure vs indicated pressure curves for the Mini-Convectron gauge tube are likely to be much different from curves for heat loss tubes made by others. Therefore, it is not safe to attempt to use calibration curves supplied by other manufacturers for their gauges with the Convectron gauge, nor is it safe to use curves for the Convectron gauge with gauges supplied by other manufacturers.

Table 3-2 Pressure vs. Indicated N2 Pressure Curve

Figure Pressure range and units Gases

Figure 3-4 10–4 to 10–1 Torr All

Figure 3-5 10–1 to 1000 Torr Ar, CO2, CH4, Freon 12, He

Figure 3-6 10–1 to 1000 Torr D2, Freon 22, Kr, Ne, O2

Figure 3-7 10–4 to 10–1 mbar (Pascal) All

Figure 3-8 10–1 to 1000 mbar (Pascal) Ar, CO2, CH4, Freon 12, He

Figure 3-9 10–1 to 1000 mbar (Pascal) D2, Freon 22, Kr, Ne, O2

Chapter 3


If you must measure the pressure of gases other than N2 or air, use Figures 3-4 through 3-9 to determine the maximum safe indicated pressure for the other gas as explained below.

Example 1: Maximum safe indicated pressure

Assume a certain system will withstand an internal pressure of 2000 Torr or 38.7 psia. For safety, limit the maximum internal pressure to 760 Torr during backfilling. Assume you want to measure the pressure of argon. On Figure 3-5 locate 760 Torr on the left hand scale, travel to the right to the intersection with the argon (Ar) curve and then down to an indicated pressure of 24 Torr (N2 equivalent). Thus in this hypothetical situation the maximum safe indicated pressure for argon is 24 Torr.

For safety, place a warning label on the instrument which under the assumed conditions would read "DO NOT EXCEED 24 TORR FOR ARGON."

Example 2: Indicated to true pressure conversion

Assume you want to determine the true pressure of argon in a system when the Convectron is indicating 10 Torr. On Figure 3-5, read up from 10 Torr (N2 equivalent) indicated pressure to the argon curve and then horizontally to the left to a true pressure of 250 Torr. Thus 250 Torr argon pressure produces an indication of 10 Torr (N2 equivalent).

Example 3: True to indicated pressure conversion

Assume you want to set a process control setpoint at a true pressure of 20 Torr of C02. On Figure 3-5, locate 20 Torr on the true pressure scale, travel horizontally to the right to the C02 curve and then down to an indicated pressure of 6 Torr (N2 equivalent). Thus the correct process control setting for 20 Torr of C02 is 6 Torr (N2 equivalent).

Example 4: True to indicated pressure conversion

Assume you want to obtain a helium pressure of 100 Torr in the system. On Figure 3-6, locate 100 Torr on the left hand scale, travel horizontally to the right to attempt to intersect the He curve. Because the intersection is off scale it is apparent that this true pressure measurement requirement for helium exceeds the capability of the instrument.

NOTES:

For gases other than those listed, the user must provide accurate conversion data for safe operation. The Mini-Convectron gauge is not intended for use above 1000 Torr true pressure.

1 mbar = 100 pascal, so the mbar charts may be used for pascal units by multiplying the values on the axes by 100.

Operation


Figure 3-4 True Pressure vs Indicated Pressure for Commonly used Gases, 10–4 to 10–1 Torr

Chapter 3



Operation



Chapter 3


Figure 3-7 True Pressure vs Indicated Pressure for Commonly used Gases, 10–4 to 10–1 mbar

Operation


Figure 3-8 True Pressure vs Indicated Pressure for Commonly used Gases, 10–1 to 1000 mbar

Chapter 3


Figure 3-9 True Pressure vs Indicated Pressure for Commonly used Gases, 10–1 to 1000 mbar


Chapter 4 Service/Maintenance

4.1 General Information It is recommended that only qualified technical personnel attempt repairs.If difficulties are encountered during use of your Mini-Convectron, the following list of symptoms and possible causes, along with the schematics, can prove useful in quickly getting back into operation.

If the prescribed remedies do not correct the troubles, or if additional assistance or special parts are required, contact the MKS Technical Support Department at +1-833-986-1686. Repairs properly made with equivalent electronic parts and rosin core solder, which do not damage other portions of the unit, do not represent a violation of the warranty.

Check Table 4-1 for the observed symptoms. This listing of symptoms and possible causes is not complete, but should be sufficient to solve most problems. All possible causes of failure should be thoroughly explored before attempting any repair.

Since the Mini-Convectron contains static-sensitive electronic parts, the following precautions must be followed when troubleshooting:

1. Use a grounded, conductive work surface.

2. Use static dissipative envelopes to store or ship printed circuit boards.

3. Do not handle the printed circuit board more than absolutely necessary, and only when wearing a ground strap.

4. Do not use an ohmmeter for troubleshooting the electronics. Rely on voltage measurements.

5. Use grounded-type soldering irons only.

4.2 Mini-Convectron Disassembly

For some of the troubleshooting procedures it will be required that the printed circuit board and gauge tube be removed from the enclosure. Proceed as follows to access the internal electronics and the gauge tube.

1. Disconnect the cable(s) on the side of the Mini-Convectron Module.

2. Remove the two screws on the front panel and remove the panel.

3. Slide the plastic case rearward to remove it from the gauge tube and electronics. Note that the PC Board guides are molded into the plastic case.

4. Unplug the PC board assembly from the gauge tube.

5. For assembly, reverse this procedure. Make sure the PC boards are in the slots of the plastic case.

Chapter 4


4.3 Troubleshooting

Table 4-1 General Symptoms/Possible Causes

Symptom Possible Causes

No power indication No input power. Verify that there is +11 Vdc to +16 Vdc between pins 4 and 9 of the I/O connector on the Mini-Convectron Module. See Figure 2-4 on page 18.

Bridge analog output voltage reads less than +0.22 Vdc or greater than +10 Vdc

Gauge tube failure. Test for gauge tube failure. Measure the resistance between the following terminals with the gauge tube at atmospheric pressure and an ohmmeter which cannot apply more than 10 mA. See Mini-Convectron Disassembly on page-31for disassembly procedures.

Bridge amplifier failure. This circuitry is located on the small PC board that the gauge tube plugs into. Check for input power to this board across the two outside fingers of the small board where it is soldered into the large board. Check that the bridge output voltage between the middle finger and the bottom finger is approximately 6 Vdc with the gauge tube at atmosphere.

Readout indicating a pressure in the system is vastly different than that being observed by supporting gauges

Gas composition on system is not what the user believes it to be. This can be caused by selective gas pumping, process in use, outgassing of product, etc. Determine gas composition and calibrate accordingly.

The gauge tube is contaminated with material from the vacuum system. Clean the gauge tube. See Convectron Gauge Bakeout Instructions on page-33 and Cleaning a Convectron Gauge on page-33. If not effective, replace gauge tube.

• Pins 1 to 2: 18 to 23 ohms• Pins 2 to 3: 50 to 60 ohms• Pins 1 to 5: 180 to 185 ohmsIf the resistance from pins 1 to 2 reads about 800 ohms, the sensor wire in the gauge is broken. Replace the gauge tube.

Note: If the resistance values shown here are correct, but you still think the gauge is not reading correctly, the gold plating on the sensor wire may be eroded and the gauge will have to be replaced.

Service/Maintenance


4.4 Convectron Gauge Bakeout Instructions

The Convectron gauge can be baked to 85 0C with the electronics attached, but not operational. To bake the Convectron gauge to a higher temperature, up to 150 0C, the electronics must be removed. See Mini-Convectron Disassembly on page-31 for disassembly procedures.

With the electronics removed, perform the bakeout up to 150 0C. Measure the temperature at the mounting flange of the Convectron gauge.

After the system has cooled down, reassemble the electronics and connect the cable(s).

4.5 Cleaning a Convectron Gauge

Prior to cleaning, the gauge tube must be removed from the electronics as described on page 31. Cleaning solvents can damage electronic components or the enclosure.

When the small sensor wire is contaminated with oil or other films, its emissivity or its diameter may be appreciably altered and a change of calibration will result. Cleaning with trichloroethylene, perchloroethylene, toluene, or acetone is possible but it must be done very carefully to not damage the sensor.

1. Hold the gauge with the main body horizontal and the port projecting upward at a 45° angle.

2. Slowly fill the port with solvent using a standard wash bottle with the spout inserted in the port to the point where it touches the screen. Let the solvent stand in the gauge for at least ten minutes. Do not shake the gauge. Shaking the gauge with liquid inside can damage the sensor wire.

3. To drain the gauge, position it horizontally with the port facing downward.

4. Allow the gauge to dry overnight with the port vertically downward and uncapped. Before re-installing the gauge on the system, be certain no solvent odor remains.

5. If the gold plating on sensor has been attacked by a gas such as fluorine or mercury vapor, changing its emissivity and/or resistance, replace the gauge tube. Cleaning cannot solve this problem.

The fumes from solvents such as trichloroethylene, perchloroethylene, toluene, and acetone can be dangerous to health if inhaled. Only use these solvents in well ventilated areas exhausted to the outdoors. Acetone and toluene are highly flammable and should not be used near an open flame or energized electrical equipment.

Chapter 4


4.6 Returning a Mini-Convectron Module for Service

Some minor problems are readily corrected on site. If the product requires service, contact the MKS Technical Support Department at +1-833-986-1686. If the product must be returned to the factory for service, request a Return Material Authorization (RMA) from MKS. Do not return products without first obtaining an RMA. In some cases a hazardous materials disclosure form may be required. The MKS Customer Service Representative will advise you if the hazardous materials document is required.

When returning products to MKS, be sure to package the products to prevent shipping damage. Shipping damage on returned products as a result of inadequate packaging is the Buyer's responsibility.

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Index

BBakeout Instructions

Convectron Gauge 33

CCaution statements 8Cleaning a Convectron Gauge 33Connector

I/O 18Power 18

Convectron GaugeBakeout Instructions 33Cleaning 33Internal Volume 13Sensing Wire Filament 13

DDifferential Analog Output 20Dimensions 18

EEnvironment for installation 17Explosion / Implosion 9

FFigures

module with two relays, no display 18Front panel 20Fumes from solvents 9

GGrounding 17

II/O connector wiring 18Indicated Pressure vs True Pressure 23Installation

environment 17grounding 17Important Precautions 15location 17Mounting orientation 16

LLethal Voltages 11Location for installation 17

MMini-Convectron module

Disassembly 31Module

Physical Dimensions 18Power Supply 13Temperature 13

PP > 100 mTorr indicator 20Physical dimensions 18Pressure Curves 23Pressure Measurement 13Pressure Measurement Range 13

RReading and Following Instructions 8

SSafety 7

instructions 7Service

Contact 34Return for Repair 34

Service Guidelines 11Specifications 13

Convectron Gauge Internal Volume 13Convectron Gauge Sensing Wire 13I/O connector 13Power Supply 13Pressure Measurement 13Temperature 13

System Grounding 11

TTemperature

Non-operating 13Operating 13

True Pressure vs Indicated Pressure 23

Index


WWarning statements 8Wheatstone Bridge Diagram 19Wiring

I/O ConnectorSpecifications 13

Series 275

Instruction Manual

Mini-Convectron® Module with Differential Output Amplifier

Instruction manual part number 275831Revision E - March 2020

Customer Service / Technical Support:


Table of ContentsSafety, Introduction, Specifications1.1 Safety Introduction1.2 Reading and Following Instructions1.3 Explosion / Implosion1.4 System Grounding1.5 Operation1.6 Service Guidelines1.7 Receiving InspectionDomestic ShipmentsInternational ShipmentsDamaged Material

1.8 Specifications

Installation2.1 Important Precautions for Mini-Convectron Installation2.2 Mounting Location and OrientationLocationEnvironment

2.3 Grounding2.4 Dimensions2.5 I/O Connector Wiring

Operation3.1 Theory of Operation3.2 Front Panel3.3 Differential Analog Output3.4 Use with Gases other than N2 and Air

Service/Maintenance4.1 General Information4.2 Mini-Convectron Disassembly4.3 Troubleshooting4.4 Convectron Gauge Bakeout Instructions4.5 Cleaning a Convectron Gauge4.6 Returning a Mini-Convectron Module for Service

Mini-Convectron Module with Differential Output Amplifier...This instruction manual is for use with...

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