1600 manual

8/3/2019 1600 Manual

1/23

8/3/2019 1600 Manual

2/23

INSTRUCTION MANUAL

FOR

NEUROPROBE AMPLIFIER

MODEL 1600

Serial #__________

Date____________

A-M Systems, Inc.

PO Box 850

Carlsborg, WA 98324

U.S.A.

360-683-8300 800-426-1306

FAX: 360-683-3525

http://www.a-msystems.com

Version 5.0June 2001
http://www.a-msystems.com/http://www.a-msystems.com/

8/3/2019 1600 Manual

3/23

NOTE

This instrument is not intended for clinical measurements using humansubjects. A-M Systems, Inc. does not assume responsibility for injury ordamage due to the misuse of this instrument.

Contents

General Description............................................................................................................................ 1Instrument Features ............................................................................................................................................. 1

Controls and Connectors ..................................................................................................................................... 2

Operating Instructions ....................................................................................................................... 7

Typical Set-Up Procedure .................................................................................................................................... 7

Power Requirements ............................................................................................................................................ 9

Headstage and Microelectrode Operation ........................................................................................................... 9

Electrode Calibration......................................................................................................................................... 11

Current Injection................................................................................................................................................ 12

Iontophoresis Adapter ........................................................................................................................................ 13

Neuroprobe Headstage Replacement Procedure ............................................................................................... 14

Problem Solving ................................................................................................................................................ 15

Specifications..................................................................................................................................... 16Current Input ..................................................................................................................................................... 16

Current Injection................................................................................................................................................ 16

Current Gate ...................................................................................................................................................... 16

Electrode Test .................................................................................................................................................... 17

Signal Processing............................................................................................................................................... 17

Outputs .............................................................................................................................................................. 18

Power Supply Requirements ............................................................................................................................. 19

Physical Dimensions ......................................................................................................................................... 19

Warranty and Service ...................................................................................................................... 20

Each Neuroprobe Amplifieris delivered complete with:

One Head Stage with a 5 Foot CableRack Mount Hardware

Instructions & Maintenance Manual

8/3/2019 1600 Manual

4/23

8/3/2019 1600 Manual

5/23

8/3/2019 1600 Manual

6/23

3A-M Systems, Inc.131 Business Park Loop, P.O. Box 850 Carlsborg, Wa 98324Telophone: 800-426-1306 * 360-683-8300 * FAX: 360-683-3525E-mail: [email protected] * Website: http://www.a-msystems.com

Capacity Controls

COMP.: This knob is used to adjust an activefeedback circuit to compensate for up to 30 pFof electrode capacitance. The capacitancecompensation can be accurately adjusted with

the electrode in the experimental preparationusing the internal square-wave generator and anoscilloscope connected to either the X1OUTPUTor the X10OUTPUT. This control should beadjusted to obtain the sharpest corners possibleon the square-wave with very little overshoot. Clockwise rotation of both parts of thiscontrol increases the capacity compensation. The outer ring provides a coarseadjustment and the inner knob allows for fine control.

IG TRIM:This control nulls the input bias current to the Headstage Probe to less than 10-13

Amp for high input impedance.

CAP. OVERRIDE:This button provides a capacitance override to send the circuit intopositive feedback and cause the electrode to vibrate. This is commonly called a tickler.When the electrode vibrates rapidly it sometimes will aid in the penetration of the cellmembrane, or clearing of a clogged electrode.

Miscellaneous Functions

HIGH RANGE:This button activates High Range Mode when pressed, changing theavailable range of injection currents. Themaximum injection current is the lesser of 2.5 V

/(electrode resistance) and either 100 nA inLow Range Mode or 1000 nA in High RangeMode. The key criterion for current rangeselection is the ability to balance the voltagedrop across the electrode. The Model 1600can balance up to 500 M in Low Range Modeand 50 M in High Range Mode.

1000 MV CALIBRATE:This button provides an accurate reference signal for calibratingexternal recording instruments. It causes 1000 mV to appear at the X1OUTPUTand 10 Vat the X10OUTPUT, in which case these two connectors are disconnected from other signalsources within the instrument.

8/3/2019 1600 Manual

7/23


10 MV CALIBRATE:This button provides an accurate reference signal for calibratingexternal recording instruments. It causes 10 mV to appear at the X1OUTPUTand 100 mVat the X10OUTPUT, in which case these two connectors are disconnected from other signalsources within the instrument.

NOTCH FILTER:This button activates filtering of power line frequency interference from thesignal. Use this filter only when absolutely necessary, since it can cause signal distortionif the frequency of the recorded signal lies in the rejection band of the Notch Filter (50 or60 Hz). Adequate shielding and grounding procedures should always be used.

ELECT TEST:This button activates a 100 Hz square-wave current source used to testelectrode resistance and to adjust the capacitance compensation. With the ELECT TESTand the METER: PROBEbuttons pressed, the METERdisplays the electrode resistance inM. (Note: Recording and reference electrodes should be in a saline solution forresistance testing.) When the electrode resistance is less than 100 M, High RangeMode should be used to maximize the signal-to-noise ratio and increase measurement

accuracy. In Low Range Mode 1 nA peak-to-peak produces 1mV/M and in High RangeMode 10 nA peak-to-peak produces 10 mV/M.

Current Injection

TRANSIENT:This knob is a dual-functiontransient control which adjusts the transientresponse of the balance circuit to duplicate thatof the Headstage Probe, allowing maximumsuppression of the transient when balancing outthe electrode response for current injection.

The smaller knob is the SLOPEcontrol; thelarger is the PEAKcontrol. The effect of both controls is increased as they are rotatedclockwise. Counterclockwise rotation of the SLOPEcontrol to BAL. OFFdeactivates theentire balance circuit. This is the preferred setting for any experiment not involvingcurrent injection, as the balance circuit creates a slight increase in noise level.

DC BALANCE: This knob controls a 10-turn potentiometer which nulls voltage drop acrossthe electrode due to current injection when recording and stimulating through the sameelectrode. This function is disabled when the TRANSIENTknob is set to the BAL. OFFposition.

CURRENT:This knob sets the level of the injection current supplied by the internal source.This level can be measured on the METERprior to injection.

POLARITY:This switch sets the output polarity of the internal current source.

8/3/2019 1600 Manual

8/23


CURRENT INJECTION (CONT-OFF-MOMEN):This switch triggers injection of the presetinjection current. The CONTsetting triggers continuous current injection which lasts untilthe switch is manually returned to the OFFposition. The MOMENsetting triggers continuouscurrent injection which lasts only as long as the switch is held in this position. The switchwill automatically return to the OFFposition after being released from the MOMENposition.

Low Pass Filter

LOW PASS: This knob controls a low pass filterwhich provides adjustable bandwidth limiting.Attenuation above the cutoff frequency is -12 dB/octave. When the switch is set to OFF, the filter isremoved from the circuit.

DC Offset

DC OFFSET KNOB:This knob sets the variable

DC offset voltage, which is summed with the input voltage. This feature may be used tocompensate for electrode potentials and to position the signal trace on an oscilloscoperecording device. An offset range of 0.0 V to 1.0 V is available at the X1OUTPUTand 0.0V to 10 V at the X10OUTPUT.

DC OFFSET SWITCH (+ OFF -):This switch sets the DC offset polarity or alternately turns thefeature OFF.

ZERO ADJ.:This control nulls any instrument offset potential when the DC OFFSET SWITCHisOFF, thereby providing a true zero offset.

Outputs

CURRENT:This BNC connector allows the valueof current supplied to the electrode to bemonitored on an external recording device.The signal is 10 mV/nA in low range (highrange button out) and 1 mV/nA in high range(high range button in).

X1OUTPUT:This BNC connector provides the measured signal (plus any DC offset) for

recording on a chart recorder or oscilloscope.

X10OUTPUT:This BNC connector provides 10 times the measured signal (plus any DCoffset) for recording on a chart recorder or oscilloscope.

8/3/2019 1600 Manual

9/23


Digital Meter

OFF:This button disconnects the METER inputsand turns off all power to the METER module,thus increasing battery endurance by about 50percent.

PROBE:This button displays the DC potential ofthe X1OUTPUT. When the ELECT TESTbutton isalso pressed, the electrode resistance isshown in M.

CURRENT:This button displays the injectioncurrent in nA, as determined by the CURRENT INJECTION: CURRENTknob and the INPUTS:CURRENTconnector. The current is displayed regardless of the CURRENT INJECTION (CONT-OFF-MOMEN)switch position or the signal level at the INPUTS: CURRENT GATEconnector.

DVM:This button allows the METERto be used as a digital voltmeter without disruptingother instrument functions. When pressed, the DVM INPUTconnector is connected directlyto the METERwhich displays the potential in mV.

DVM INPUT: This BNC connector allows direct access to METERfor use as a digitalvoltmeter. The available range is 1999 mV.

Power Supply

POWER: This button is the main power switch, controlling the DC power input to the maincircuit of the instrument. The switch face is lit when the instrument isON. This button does

not control the power input to the AC Power Supply or AC Battery Charger Adapter(optional). To power the instrument with the AC Power Supply, the AC power switchlocated on the back panel of the instrument must be ON. Please turn the AC PowerSupply OFFafter using the instrument.

BATT LOW:This LED illuminates when the battery becomes discharged. In an ACpowered instrument this LED performs no function.

Rear Panel

CHARGER CONNECTOR (OPTIONAL):This connector provides an input for the battery

charger to recharge the battery.

AC POWER SUPPLY SWITCH:This switch connects the AC power source to the PowerSupply. This must beONto provide power to the DC Power Switch located on the frontpanel. Please do not forget to turn this switch OFFafter use.

8/3/2019 1600 Manual

10/23


Operating Instructions

Typical Set-Up Procedure

This is a generalized procedure for setting up the Neuroprobe Amplifier Model 1600forintracellular recording and stimulation. Portions of this procedure may need to bemodified for your specific application.

1. Connect the Headstage Probe cable to the PROBE connector.

2. Set the instrument controls as follows:

LOW PASS OFF

DC OFFSET knob counterclockwiseDC OFFSET (+ OFF -) OFFTRANSIENT: SCOPE knob BAL. OFFTRANSIENT: PEAK knob counterclockwiseDC BALANCE counterclockwiseCURRENT INJECTION (CONT-OFF-MOMEN) OFF

CAPACITY COMP. counterclockwiseELECT TEST OFF

NOTCH FILTER OFF

10 MV CALIBRATE OFF

1000 MV CALIBRATE OFF

HIGH RANGE OFFMETER PROBE

3. Turn on power to the Model 1600and allow it to warm up for 5 minutes.

4. Mount a micropipette in a micropipette half-cell type holder, which in turn is connectedto the Headstage. Clamp the Headstage in a micromanipulator.

5. Connect the reference electrode to the GNDconnector.

6. Dip the micropipette and the reference electrode into a beaker of physiological salinesolution (or the solution in which the tissue will be bathed). The solution should havethe same temperature and ionic strength as that in which measurements will be

made. Note: immerse the micropipette to approximately the same depth as will beused during the measurement.

7. Observe the offset potential between the two electrodes displayed on the METER. Setthe DC OFFSET (+ OFF -)switch to the appropriate polarity and adjust the DC OFFSETknob to zero the digital display and amplifier outputs.

8. Connect an oscilloscope to either the X1or X10OUTPUT, with the horizontal sweeprate set to 2ms/division.

8/3/2019 1600 Manual

11/23


9. Press the ELECT. TESTbutton to inject a 100 Hz square-wave current through theelectrode. The digital display now indicates electrode resistance in M. If this valueis less than 100 M, press the HIGH RANGEbutton to obtain greater accuracy.

10. Adjust the oscilloscope for a good display of the square-wave.

11. Increase the CAPACITY COMP.to square-up the corners of the waveform. Avoid

overcompensation, which will cause ringing, excessive noise, and high frequencyoscillation.

12. Press the ELECT. TESTbutton to stop the test signal.

13. If the electrode resistance is less than 50 M, ensure that the HIGH RANGEbutton ispressed to operate in High Range Mode.

14. Press theMETER: CURRENTbutton.

15. Set thePOLARITYswitch to the desired current polarity and adjust the CURRENTknobto the maximum current level which will be injected during the experiment.

16. Connect the current gating signal to the CURRENT GATEinput and adjust the signal

source for a repetitive waveform with a pulse duration similar to that which will beused in the experiment.

17. If available, connect a second oscilloscope channel to the OUTPUTS: CURRENTconnector. Two signals, one directly proportional to the injection current, and the otherrepresenting the resultant voltage drop across the electrode, should now be available.

18. Rotate the TRANSIENT: SCOPE knob slightly clockwise to activate the current balancecircuitry.

19. Adjust the DC BALANCEknob to remove the electrode voltage drop from the outputsignal.

20. Adjust the SCOPEand PEAKcontrols of the TRANSIENTknob to minimize transientsoccurring when the current is gated on and off.

21. If the injection current magnitude is to be controlled by an external signal, connect thissignal to the INPUTS: CURRENTconnector. Remember this signal will be summed withthe setting of the CURRENTknob, with the total current displayed when the METER:CURRENTbutton is pressed. The current is injected only when triggered by theCURRENT INJECTION (CONT-OFF-MOMEN)switch or by the signal applied to the CURRENTGATEinput.

22. If the electrode test capability will be used, apply an appropriate control signal to theELECTRODE TESTconnector.

23. Connect the desired recording device to the output connector(s).24. Apply the electrodes to the experimental preparations.

25. If needed, connect an electrode shield to the driven shield ring on the Headstage.

26. Apply the LOW PASSfilter and NOTCH FILTERif necessary.

8/3/2019 1600 Manual

12/23


Power Requirements

Most units are powered by a standard AC supply (115/230 VAC), although some units cancome with a battery power supply. Before use, the battery must be charged overnight byplugging the battery charger into a 115/230 VAC power source and the cable into theconnector on the rear panel of the Model 1600. Note: Check your power sourcevoltage and charger setting before attempting to charge the battery.

The Model 1600may be used while it is connected to the battery charger, in which casethe battery charge will not be depleted. However, for maximum stability of the input currenttrim (IG Trim), we recommend that the instrument is operated on battery power alone.

The battery can power the amplifier for about 10 hours with the METEROFF. The BATT.LOWindicator light will come on when the battery charge is low. A protection circuit turnsthe unit off if the voltage drops too low, thus preventing battery damage due to excessivedischarge.

The Model 1600should be warmed up for 30 minutes before any critical adjustments aremade.

Headstage and Microelectrode Operation

Headstage Cable Connections

The Headstage cable is connected to the PROBEconnector on the front panel of theinstrument or directly to the Iontophoresis Adapter Model 6820if used. Note: Always

connect and disconnect thePROBE cable with thePOWER OFF.

Headstage Care

To preserve the high input impedance, the connector end of the headstage must be keptmeticulously clean and dry. Contamination on the insulation between the input connector,driven shield and case (even from contact with fingers) can cause current leakageparticularly in the humid environment surrounding most experimental preparations. Usetissue paper to wipe this area clean and ensure that all micropipette holders are cleanand dry before attaching them to the Headstage. Also, observe the 10 V limit at theHeadstage input. The input FET is protected against static charge however there is no

overvoltage protection since such circuitry would result in a loss of input impedance. Beparticularly careful near high voltage stimulators.

Mounting Micropipettes

8/3/2019 1600 Manual

13/23


The easiest way to mount a micropipette is with ahalf-cell type holder (Catalog #s 6410-6465). Thisholder should have a 0.08 inch (2.0 mm) diameterpin connector to fitthe headstage. Fill the holderwith the same solution as the micropipette, typically3M KCl. Be sure there are no air gaps which couldcause discontinuity in the electrical connection between the micropipette and holder.

If the micropipette must have freedom of movement or float, as when recording frommoving muscle fibers, place the end of a thin chloride silver wire into the stem of a filledmicropipette, securing the wire at the open end of the pipette with a fast-drying cement.Solder the other end of the wire to 0.080 inch (2.0 mm) diameter pin connector (Catalog #5210). Coil the wire between the pipette and pin connector into spring. Insert the cleanand dry pin connector in the Headstage.

Driven Shield and Ground Connections

The Headstage circuitry is enclosed by a drivenshield maintained at the same potential as theinput connectors, thus there is no electric fieldbetween the input connections and shield, andtherefore, no capacitive shunting. This shield isbrought out of the Headstage case through the gold ring surrounding the input connector.This connecting ring may be used to extend the driven shield to the micropipette holderand micropipette. Shielding the electrode and holder is recommended since this portionof the circuit is particularly sensitive to stray electric fields, due to the high impedance ofthe electrode tip and the Headstage input. Using a driven shield for this purpose has the

advantage of not introducing any additional shunt capacitance nor a path for currentleakage to ground.

A shield can be made from a coil of wire wrapped around the shield ring and extendedalong the length of the electrode holder and electrode. Foil or other conductive coatingson the electrode surface can also be used for shielding. Note: Make certain that thedriven shield does not contact either the Headstage case or the experimentalpreparation, as both are at ground or reference potential and such contact will preventproper circuit operation.

The Headstage case and GNDconnector are both connected to the circuit ground. This

can be used for connecting the reference electrode in situations where it is inconvenientto run a separate reference cable to the experimental preparation. Such a connection canbe made directly to the headstage case with a 6-32 x 1/4-inch machine screw insertedinto the tapped hole in the case near the Headstage cable opening.

Mounting the Headstage in a Micromanipulator

Half Cell Holder # 6455

8/3/2019 1600 Manual

14/23


The Headstage should be clamped in the micromanipulator by means of the mounting rodsupplied. The mounting rod can be screwed into the cable end of the headstage for in-linemounting, or attached to the adjustable clamp for rightangle mounting. The latterarrangement is generally preferable since it is less sensitive to vibration.

Electrode Calibration

To inject currents and measure membrane potentials accurately compensation must bemade for the characteristics of each individual electrode. Electrodes have three keyproperties: offset potential, resistance, and capacitance.

Any conductive material placed in an ionic solution has a potential with respect to thatsolution known as the half-cell potential. This potential is a function of the materialcomposition of the electrode, the ions in the solution, ionic activity, and temperature. Thepotential between two electrodes in a solution is equal to the difference between their half-

cell potentials. Ideally, two identical electrodes should have zero potential between them,but small differences in surface properties usually are noticed as a small potentialdifference.

Most intracellular measurements are made with 3M KCI filled micropipettes which containor contact Ag/AgCl to form an electrolyte to metal junction. A second Ag/AgCl electrode isgenerally used as a reference. If the micropipette and reference electrodes are placed inphysiological saline, which duplicates the chloride concentration of most biological fluids,a potential difference will be observed. This potential occurs because the Ag/AgClelectrode in the micropipette sees the Cl concentration of the 3M KCl, which is much

higher than that of the saline surrounding the reference electrode. There should be nosignificant potential due to concentration gradients at the electrode tip, since potassiumand chloride ions have approximately the same ionic mobilities. Thus, to accuratelymeasure the potential across a cell membrane, it is necessary to null the electrodepotential using the DC OFFSETcontrol. Alternately, one may use an Ag/AgCl electrodesurrounded by 3M KCl as a reference electrode. To accomplish this, use an agar bridgeor standard pH reference electrode with an Ag/AgCl internal (Catalog # 5330).

The micropipette resistance, which normally ranges from 10 to several hundred M, isnormally of little concern for measuring potentials, due to the high input impedance of theModel 1600. However, when injecting currents through a recording electrode, voltage

drop will appear across the electrode resistance and be recorded along with themembrane response. Since the membrane response alone is desired, the electroderesponse must be subtracted from the signal. This is accomplished through the DCBALANCE.

8/3/2019 1600 Manual

15/23


The electrode also has capacitance, which is in parallel with the resistance. Thiscapacitance acts as a shunt which attenuates the higher frequency components of thesignal. The CAPACITY COMPensation is adjusted to accentuate these higher frequencies,thus compensating for the loss.

For current injection, it is also necessary to adjust the balance circuitry to compensate forthis capacitance. The waveform which is subtracted from the recorded signal must haveprecisely the same rise-time and shape as the electrode voltage drop, or a transientspike will be observed in the signal whenever injected current turns on or off. Thiswaveform is adjusted with the SLOPEand PEAKportions of the TRANSIENTcontrol. Note:some types of micropipettes exhibit nonlinear impedance characteristics. When theseare severe, the amplifier cannot fully compensate for them and the result is a transientsignal upon current injection. The magnitude and shape of this transient should berecorded during initial setup, then later manually subtracted from the recorded signalsto obtain the true membrane response.

Current Injection

The Model 1600offers several options for controlling injection current to allow for avariety of experimental preparations.

The basic configuration requires no additional instrumentation. The injection currentmagnitude is established with the CURRENTknob, and injection takes place when theCURRENT INJECTION (CONT-OFF-MOMEN)switch is set to either CONTor MOMEN. In theMOMENtary position, the current is injected only as long as the switch is held down. This

mode of stimulation is generally useful for sub threshold membrane conductivity studiesusing continuous DC stimulation.

Most studies, however, require precise control of injection current pulse duration andrepetition rate in addition to magnitude. The easiest configuration for this type ofexperiment includes a function generator or another signal source to control the pulseduration and repetition rate, and the CURRENTknob to set the injection current magnitude.The signal source is applied to the CURRENT GATEconnector. This input requires a signalgreater than +2.5 V to turn the injection current on and less than +0.6 V to turn the injectioncurrent off. The maximum voltage limit for this connector is +15 V.

When external control of current magnitude is also required, a control signal may beapplied to the INPUTS: CURRENTconnector. The injection current is proportional to thevoltage of the control signal. The final injection current is obtained by adding the controlsignal current to any current set by the CURRENTknob. Current switching remains underthe control of the CURRENT INJECTION (CONT-OFF-MOMEN)switch or the CURRENT GATEconnector as discussed above. When complete control over current magnitude andtiming is desired through only one signal, the CURRENT INJECTION (CONT-OFF-MOMEN)switch may be set to CONTand the CURRENTknob rotated fully counterclockwise. These

8/3/2019 1600 Manual

16/23


settings zero the internal current source and provide continuous injection of the currentapplied to the INPUTS: CURRENTconnector. Thus, current magnitude, polarity, and durationare all controlled by the signal applied to the INPUTS: CURRENTconnector, with currentinjection stopped when the input signal is zero.

The current control capabilities of the Model 1600may be combined in various ways tosimplify otherwise complex control situations. For example, if it is necessary to modulatethe amplitude of a train of current pulses, a pulse signal can be applied to the CURRENTGATEconnector which will establish the duration and repetition rate, while the amplitudemodulation signal (frequently a ramp or triangle waveform) is applied to the INPUTS:CURRENTconnector. As another example, if a continuous injection current, interrupted bypulses of differing magnitudes and polarity is desired, the base injection current level canbe established by the CURRENTknob and the POLARITYswitch. A signal applied at theINPUTS: CURRENTconnector can provide the pulses of differing magnitude and polaritywhich will be summed with the internal injection current source.

Iontophoresis Adapter

An Iontophoresis Adapter Model 6820(Catalog# 6820) isavailable for use with the Model 1600to apply high voltagesto the micropipette for iontophoretic injection of drugs ordyes, or any other application where currents greater thanthose provided by the Model 1600are required.

The Model 6820is connected between the Headstage

Probe and the Model 1600. Its selector switch determinesthe mode of operation. When the switch is in the INT position, routine recording andinjecting operations can be performed with the Model 1600as if the Model 6820werenot present. For iontophoretic techniques, switch to the EXTposition. Up to 200 V canbe applied to the electrode to permit injection of dyes or drugs into the cell. The injectioncurrent equals the voltage applied to the + and - terminals on the Model 6820divided bythe sum of the electrode resistance and the 9.0 M protective resistance of theHeadstage. The - terminal on theModel 6820is connected internally to the system GND.Note: potential and injected currents cannot be monitored by the amplifier while theModel 6820 selector switch is set to theEXTposition, due to Headstage isolation.

Neuroprobe Headstage Replacement Procedure

8/3/2019 1600 Manual

17/23


1. Turn off power to the Model 1600.

2. Connect the Headstage Probe cable to the PROBE connector.

3. Ground the input pin of the headstage to the GND connector.

4. Set the instrument controls as follows:

LOW PASS OFFDC OFFSET knob counterclockwiseDC OFFSET (+ OFF -) OFF

TRANSIENT: SCOPE knob BAL. OFFTRANSIENT: PEAK knob counterclockwiseDC BALANCE counterclockwiseCURRENT INJECTION (CONT-OFF-MOMEN) OFF

CAPACITY COMP. counterclockwiseELECT TEST OFF

NOTCH FILTER OFF

10 MV CALIBRATE OFF

1000 MV CALIBRATE OFF

HIGH RANGE OFF

METER PROBE

5. Turn on power to the Model 1600and allow it to warm up for 15 minutes.

6. Adjust the ZERO ADJ.control for a reading of 000 on the METER.

7. Connect a 1 G resistor between the Headstage input connector and GND. Theresistor must be shielded (aluminum foil wrapped around the resistor and connectedto the chassis will suffice).

8. Adjust the IG TRIMcontrol for a reading of 000 on the METER.

Problem Solving

8/3/2019 1600 Manual

18/23


If the Model 1600does not function properly, consult the following list which suggestssolutions to the most common problems. If you need further assistance, please contactcustomer service at A-M Systems, Inc. at the numbers listed on the title page of thismanual.

Problem Cause / Solution

Excessive offset potential Instrument oscillates due to excessive capacitancecompensation. Turn CAPACITY COMPcounter-clockwise.

Incorrect potential reading Ensure that ELECT TEST is OFF, CURRENT INJECTIONis OFF, DC OFFSETand DC BALANCEare OFForproperly adjusted, and CALIBRATEbuttons are OFF.Also, see above.

Incorrect response to Electrode impedance may be too great for desiredinjected current current level. Also, see above.

Meter out of range Excessive input potential or open electrode circuit.(flashing zeros) Check for good connections in micropipette and(just a 1.) reference electrode circuit, and for bubbles in

micropipette or holder.

Electrode impedance Excessive noise included in signal. Make impedanceincorrect or unstable measurement using HIGH RANGEwhenever possible,

and shield electrodes if necessary.

DC BALANCEcannot be set Check electrode impedance and set HIGH RANGEtoONor OFFas needed. Also, see above.

Transients cannot be Check setting of CAPACITY COMP. Also, somebalanced out transients are due to non-linear electrode impedance

characteristics and cannot be fully corrected. Mostproblems are due to improper control settings. Seethe section Typical Set-Up Procedure in thismanual for further assistance.

8/3/2019 1600 Manual

19/23


Specifications

Current Input

Impedance 1011Capacitance Adjustable to zeroWorking range 2.5 VMaximum range 10 VIontophoresis adapter input 200 V

Current Injection

External Source

Input impedance 20 kFrequency range DC to 250 kHzLow range maximum current 10 nA/VLow range maximum voltage lesser of 10 V and

( 2.5 x 108 V)/(electrode resistance)High range maximum current 100 nA/VHigh range maximumvoltage lesser of 10 V and

( 2.5 x 107 V)/(electrode resistance)

Internal SourceLow range maximum current lesser of 100nA and

2.5 V/(electrode resistance)High current range lesser of 1000 nA and

2.5 V/(electrode resistance)

Current Gate

ON signal + 2.5 V (step with rise time 10 sec)OFF signal + 0.6 V

Maximum input 15 VInput impedance 20 k

8/3/2019 1600 Manual

20/23


Electrode Test

External Signal Source

Input impedance 10 kInput voltage range 10 V

Scale factor (X1 OUTPUT) Low Range: 1 mV / M/ (input voltage)High Range: 10 mV / M/ (input voltage)

Internal Signal Source

Signal 100 Hz square waveLow range scale factor (X1 OUTPUT) 1 nA peak-to-peak produces 1 mV/MHigh range scale factor (X1 OUTPUT) 10 nA peak-to-peak produces 10 mV/M

Signal Processing

Input Bias Current

Optimal Adjustable to zeroMaximum without adjustment Low Range: 3 x 10-12 Amp

High Range: 3 x 10-11 AmpDrift versus temperature Low Range: 1 x 10-13 Amp/C

High Range: 1 x 10-12 Amp/CDrift versus time Low Range: 3 x 10-13 Amp/12 hours

High Range: 3 x 10-12 Amp/12 hours

Frequency Response

Frequency range DC to 325 kHz

Rise Time

Square wave (500 mV) 50 source: 0.8 sec, 10% to 90%20 M source: 7.0 sec, 10% to 90%

(Compensation set for 10% overshoot)

Zero StabilityStability versus temperature 200 V/ CStability versus time 1 mV/12 hours

Low Pass Filter

Cut-off frequencies (-3dB) 1, 2, 5, 10, 20, 50, and 100 kHzSlope -12 dB/octave

8/3/2019 1600 Manual

21/23


Notch Filter

Center frequency 50 Hz or 60 Hz (factory preset)Q 10Rejection -50 dB

Capacitance Compensation

Range -4 pF to +30 pF

Internal Calibration Voltage

10 mV 1%1000 mV 1%

Noise0 source 13 V RMS (10 Hz to 50 kHz)1 M source 79 V RMS (10 Hz to 50 kHz)20 M source 310 V RMS (10 Hz to 50 kHz)

(Compensation set for 1% overshoot)

DC Balance

Low range up to 500 MHigh range up to 50 M

Outputs

x 1 output

Voltage gain 1.00 0.1%Maximum voltage 10 VImpedance 220 DC Offset range 0.0 V to 1.0 V

x 10 outputVoltage gain 10.0 1.0%Maximum voltage 10 VImpedance 220 DC Offset range 0.0 V to 10.0 V

Current Monitor

8/3/2019 1600 Manual

22/23


Low range scale factor 10 mV/nAHigh range scale factor 1 mV/nAMaximum output 1.0 VOutput impedance 1 k

Digital Volt Meter (DVM)Range 1.999 VAccuracy 0.1% least significant digitInput impedance 1 MResolution 1 mV

Power Supply Requirements

AC Power

Power source 115/230 VAC input (factory preset)

Battery Power

Battery 28 V Nickel Cadmium rechargeableCharge endurance METER ON: Approx. 10 hours

METER OFF: Approx. 20 hoursCharge time 12 hours after full discharge

Charge life 75% after 1 month50% after 3 months

AC battery charger 115/230 VAC input (switch selectable)Low battery Indicator illuminates at approx. 12 V

Physical Dimensions

Amplifier

Width 17 inches (43.2 cm)Height 4.75 inches (12.1 cm)Depth 11.25 inches (28.6 cm)Weight AC Power: 22 lbs.

Battery Power: 24 lbs.

Headstage Probe

Input connector 0.08 inch (2.0 mm) female pin connectorCase diameter 0.44 inch (1.1 cm)Case length 4.00 inches (10.2 cm)Mounting rod diameter 0.187 inch (4.7 mm)Mounting rod length 3.75 inches (9.5 cm)

8/3/2019 1600 Manual

23/23

1600 manual

Documents