TEC Troubleshooting Guide - NPI Electronic Instruments
Contents
1. and SUBCLICK connector respectively gives access to the cell via a potential and current electrode with 1 MQ resistance In the upper position the Rm switch simulates a cell membrane with a resistance of 10 kQ In the lower position a cell membrane with 100 kQ is simulated The membrane capacity is always 100 nF 2 4 Testing Operation Modes Important The TEC 03X should be used only in warmed up condition i e 20 to 30 minutes after turning power on General Considerations The key to accurate and fast recording is a properly built setup e Make sure that the internal system ground is connected to only one point on the measuring ground and originates from the potential headstage Multiple grounding should be avoided all ground points should originate from a central point The electrode used for grounding the bath should have a low resistance so that it can pass large currents e Use electrodes with resistances as low as possible e Keep cables short e Use differential potential recording and a driven shield configuration version 1 6 page 5 TURBO TEC Troubleshooting Guide e Check regularly whether cables and connections are broken very important e Make sure that chloriding of silver wires for the electrodes is proper and that there are no unwanted earth bridges e g salt bridges originating from experimental solutions Current Clamp In the current clamp mode the cell s response to current injections is measured Current2. injection is performed by means of a current source connected to the current injecting microelectrode Important In case of trouble first check whether all connections are built correctly and make sure that the oscillation shut off unit is not active LI Connect a cell model and turn power on Watch the OSCILLATION SHUTOFF unit The LED 3 must light green If not Y disable the unit with switch 2 LJ With the MODE OF OPERATION switch 28 set the amplifier to CC mode LED 27 should light up _ If not already done tune the BIAS current to zero see chapter 8 1 user manual for TEC 03X or page 21 for TEC 10CX _ Compensate the offsets of the current and voltage electrode using offset controls 16 and 18 see chapter 8 2 user manual for TEC 03X or page 8 for TEC 10CX Displays should read values around zero If not check V HOLD disabled V Electrode resistance test disabled V BIAS current adjusted V Capacity compensation set to 0 J No signal at COMMAND INPUT if you are not sure disconnect Offset cannot be compensated gt headstage may be damaged contact npi If all works correctly LI Test the resistance of the current and the voltage electrode see chapter 8 3 user manual Display should read 1 MQ 5 If not check V npi cell model connected should mean are really 1 MQ electrodes simulated V Range switch at current headstage in position 1 This is a must for correct display of the resista
3. of slightly less than 50 mV because the controller is in normal gain only mode without INTEGRATOR see also Appendix in the User Manual and the GAIN is low Increasing GAIN and setting INTEGRATOR TIME CONSTANT Integrator mode will enhance the control loop and therefore increase accuracy TEC 03X and TEC 10CX If the system oscillates as soon as you switch to VC mode switch back to CC mode and check the settings V GAIN too high Y Y CAPACITY COMPENSATION not zero V TRESHOLD potentiometer of the OSCILLATION SHUTOFF unit at the most left position TEC 03X V Control mode switch not to NORMAL GAIN ONLY or SLOW Integrator version 1 6 page 8 TURBO TEC Troubleshooting Guide TEC 10CX V INTEGRATOR TIME CONSTANT on and set to a too high value V SERIES RESISTANCE COMPENSATION on and set to a too high value If all works correctly m Apply a test pulse of 20 mV to the cell model by giving a voltage step of 0 2 V to COMMAND INPUT 31 TEC 03X or VOLTAGE COMMAND INPUT 10 TEC 10CX The length of the test pulse should be at least 30 ms You should see a potential step of 200 mV amplitude at Pg 33 TEC 03X or Pet x10 TEC 10CX If not V Contact npi Note If you expect the POTENTIAL display to show the value of the potential step in this case 20 mV amplitude i e 30 mV remember that the display is rather sluggish and may not display the right value depending on the length of the step The same is true for t
4. same applies to the CURRENT display Voltage Clamp In voltage clamp mode the membrane potential is forced by a controller to maintain a certain value or to follow an external command That allows measurement of ion fluxes across the cell membrane This is the most complex mode of operation with the TEC 03X or TEC 10CX Special precautions must be taken while tuning the control circuit in order avoid stability problems TEC 03X _ Make sure that the amplifier works correctly with the cell model in CC mode see above L Set the holding potential to 50 mV using the HOLD potentiometer 12 reading 050 mV and the HOLD potential polarity switch 25 set to Remember The HOLDING potentiometer sets the holding current in CC mode and the holding potential in VC mode LJ Set the control mode switch 6 to NORMAL GAIN ONLY LI Set the CAPACITY COMPENSATION to zero and the GAIN 5 to 1 L Enable the OSCILLATION SHUTOFF unit with a moderate THRESHOLD DISABLED RESET switch 2 in middle position OSCILLATION SHUTOFF LED green TRESHOLD potentiometer set to a low value but not to the most left position version 1 6 page 7 TURBO TEC Troubleshooting Guide For troubleshooting with the cell model you should disable the OSCILLATION SHUTOFF unit Set the amplifier with the MODE OF OPERATION switch 28 to VC mode The upper display should show the holding potential of 50 mV and the lower display the holdi
5. 9 3 zt fo je o 3 n x x a 3 i gt 2 o 8 _ 2 gt i e O O Figure 1 TURBO TEC 03X front panel view version 1 6 page 3 TURBO TEC Troubleshooting Guide 2 1 Electrical connections All numbers are related to Figure 1 L Turn POWER off L Connect the TEC 03X to mains using the mains cord _ Connect the potential headstage cable to the POTENTIAL HEADSTAGE connector 20 at the TEC 03X _ Connect the current headstage cable to the CURRENT HEADSTAGE connector 22 at the TEC 03X L Connect a cell model see chapter 2 3 _ Connect a digital analog timing unit e g a computer with multifunction I O board or a stimulation device e g a pulse generator to COMMAND INPUT 31 TEC 10CX Connect a digital analog timing unit e g a computer with multifunction I O board or a stimulation device e g a pulse generator to CURRENT STIMULUS INPUT 1V uA for Current Clamp CC or to VOLTAGE COMMAND INPUT 10 for Voltage Clamp VC LI Connect a storage oscilloscope or a data recording device e g a computer with data acquisition card to the POTENTIAL OUTPUT Peg and to the CURRENT OUTPUT triggered from the stimulation device We recommend always to use an oscilloscope in addition to the computer system Set the desired gain at the CURRENT OUTPUT SENSITIVITY switch 15 and set the CURRENT FILTER 14 to 20k TEC 10CX Connect a storage oscilloscope or a data recording device e g a compu
6. Electronic npi Instruments for the Life Sciences pease ade TURBO TEC 03X TURBO TEC 05X TURBO TEC 10CX TROUBLESHOOTING GUIDE TURBO TEC 03X en npl 4 s O 0 Oe MOE OF COMMAND PUI VERSION 1 6 npi 2013 npi electronic GmbH Bauhofring 16 D 71732 Tamm Germany Phone 49 0 7141 9730230 Fax 49 0 7141 9730240 support npielectronic com http www npielectronic com TURBO TEC Troubleshooting Guide 1 Intention of this Guide This manual is written to enable the user to set up and test the basic functions of a Turbo TEC amplifier from npi Furthermore some hints are given for the case that something goes wrong and it should help to find errors Front panel controls and connectors refer to the TEC 03X amplifier but the following instructions are also valid for TEC 05X and TEC 10CX amplifiers With TEC 05X and TEC 10CX amplifiers please follow these tests analogue to TEC 03X TEC 05X and TEC 10CX have different front panel elements In the test procedures these elements are mentioned separately version 1 6 page 2 TURBO TEC Troubleshooting Guide 2 Testing basic functions of TURBO TEC 03X amplifier In the following instructions are given to test the basic functions of TEC 03X amplifiers and to exclude simple errors see also TURBO TEC 03X user manual o o O N N oT N 9 N ae N lt T n o N a N wW N N N p ae N o g amp o o 3 gt N m
7. he CURRENT display 3 Testing the cell model All you need for this test is a simple ohmmeter Please run these test with the switch for grounding the current electrode set to ON m m Test 1 Measure the resistance between the two inputs i e the inner contacts of Per and CEL at the cell model The resistance must be 2 MQ Test 2 Measure the resistance between Pg inner contact and GND plug Switch the membrane resistance to 10k The resistance must be 1 011 MQ Switch the membrane resistance to 100k The resistance must be 1 101 MQ Test 3 Measure the resistance between Cpr inner contact and GND plug Switch the membrane resistance to 10k The resistance must be 1 011 MQ Switch the membrane resistance to 100k The resistance must be 1 101 MQ Test 4 Measure the resistance between REF inner contact and GND plug The resistance must be 2 kQ Test 5 Verify that there is a connection between the shields outer part of the plugs of CeL and REF to GND respectively Test 6 Verify that there is no short circuit between GND and the shield of the potential electrode i e the ohmmeter must display infinite If you measure these values the cell model is OK version 1 6 page 9
8. nce V Cell model OK see also chapter 3 of this guide Vv If this is the case the headstage may be damaged gt contact npi If all works correctly LJ Set Rn at the cell model to 10k version 1 6 page 6 TURBO TEC Troubleshooting Guide L Set the holding current to 1 uA using the HOLD potentiometer 12 reading 1 00 uA and the HOLD current polarity switch 25 set to _ Make sure that the potential switch 7 is set to POTENTIAL electrode and the ELECTRODE RESISTANCE test is not active The POTENTIAL display should read 10 mV according to Ohm s law The voltage at Pe 33 should be 100 mV If not check POTENTIAL switch 7 set to POTENTIAL ELECTRODE V HOLD current polarity switch 25 set to V ELECTRODE RESISTANCE disabled Remember The voltage at Per x10 is the membrane potential multiplied by 10 LI Disable the holding current and apply a test pulse of 2 uA to the cell model by giving a voltage step of 2 V to COMMAND INPUT 31 The length of the test pulse should be at least 50 ms You should see a potential step of 200 mV amplitude at Pg 33 Due to the membrane capacity the step is smoothed If not V amplifier might be damaged gt contact npi Note If you expect the POTENTIAL display to show the value of the potential step in this case 20 mV amplitude remember that the display is rather sluggish and may not display the right value depending on the length of the step The
9. ng current of 5 uA according to Ohm s law It is very likely that the display shows a holding potential of slightly less than 50 mV because the controller is in NORMAL GAIN ONLY mode see also Appendix in the User Manual and the GAIN is low Increasing GAIN and setting the controller to SLOW Integrator mode will enhance the control loop and therefore increase accuracy TEC 10CX m m U O O O L Make sure that the amplifier works correctly with the cell model in CC mode see above Set the holding potential to 50 mV using the HOLDING POTENTIAL potentiometer reading 050 mV and the HOLDING POTENTIAL polarity switch set to Set the VC OUTPUT LIMITER to 100 Set the COMMAND FILTER TIME CONSTANT to 10 us Set the SERIES RESISTANCE COMPENSATION to OFF Set the INTEGRATOR TIME CONSTANT to OFF Set the CAPACITY COMPENSATION to zero and the GAIN to 1 Enable the OSCILLATION SHUTOFF unit with a moderate THRESHOLD DISABLED RESET switch in middle position OSCILLATION SHUTOFF LED green THRESHOLD potentiometer set to a low value but not to the most left position For troubleshooting with the cell model you should disable the OSCILLATION SHUTOFF unit Set the amplifier with the MODE OF OPERATION button to VC mode The upper display should show the holding potential of 50 mV and the lower display the holding current of 5 uA according to Ohm s law It is very likely that the display shows a holding potential
10. ter with data acquisition card to the POTENTIAL OUTPUT Pg x10 and to the CURRENT OUTPUT triggered from the stimulation device TURBO TEC 03X Current Potential DAC Stimulation device ADC Oscilloscope Headstage Headstage Figure 2 basic electrical connections Before using the TEC 03X always make the basic settings see below to avoid oscillations version 1 6 page 4 TURBO TEC Troubleshooting Guide 2 2 Basic settings It is assumed that the BIAS current has been tuned to zero see respective TEC manual L Turn all controls to low values less than 1 and each symmetrical offset adjustment in the range of 5 zero position For users of the four range headstage LI Set the range switch to x1 L Disable the HOLD unit by setting the 0 switch 25 to 0 L Set the MODE OF OPERATION 28 to CC L Set the display to POTENTIAL ELECTRODE using switch 7 2 3 Connecting the cell model L Connect the Pg BNC jack of the cell model to the BNC connector at the potential headstage L Connect the SUBCLICK connector REF to the REF connector at the potential headstage _ Connect the SUBCLICK connector Cp to the plug at the current headstage LI Switch the CELL membrane switch at the cell model to 100K L Set the GND switch at the cell model to ON _ Turn POWER switch of the amplifier on Now you can adjust the amplifier and apply test pulses to the cell model see below Connection to the BNC
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