INSTRUCTIONS PS2500 POWER SUPPLY

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2 INSTRUCTIONS PS2500 POWER SUPPLY The Hoefer PS 2500 Power Supply will furnished power to Constant Voltage or Constant Power modes of operation. It will accurately supply volts, ma or watts. (It can be run at volts in combination with 150 ma or volts in combination with 300 ma.) In addition to these normal functions, the PS 2500 has a programmable automatic crossover feature that switches the unit from the Constant Current or Constant Power mode to Constant Voltage when a preset voltage is reached during a run. 1. Specifications Constant Voltage VDC Constant Current VDC VDC Constant Power 0-375W Load Regulation < ±0.1%, 100% Load Change Line Regulation No measurable effect in output at full load- <0.1% VAC, VAC Ripple and Noise: <0.2% Power Requirement: 115 V, 60 Hz or 230 V, 50 Hz Fuse Specifications: 375 Amp, 3 AG -5 Amp SB, 3 AG 6.25 Amp SB, 3 AG The voltage reading on the LED is the same across all sets of jacks; the current and power readings are the sum of the loads connected to all sets of jacks. If the loads are of differing resistance, each may be briefly connected singly to check what current or power it pulls. 2. Procedure A. Normal Run 1) Turn the MAIN ADJUST knob fully counterclockwise. 2) Set the program selector knob (lower knob in the right row) to NORMAL 3) Set the MODE CONSTANT select knob to CURRENT, POWER, or VOLTAGE. 4) Set the CURRENT RANGE knob and the VOLTAGE RANGE knob to the expected operating ranges. Current and voltage are limited automatically to approximately 105% of the range selected. Be Sure You Choose The Correct Range. (The range choices are 0-5 ma, 0-50 ma, or ma (0-150 ma with 0-250OV) for current; 04W V, V, V for voltage.) 11985/ Hoefer Scientific & Instruments.654 Minnesota St. -San Francisco, CA (415) Instructions - PS 2500 Power Supply 2

3 CAUTION! To prevent thermal overload, do not operate the PS 2500 in a voltage range higher than needed for your experiment See Procedure, C. Thermal Overload. 5) Connect the power supply to your electrophoresis unit. 6) Turn the power supply on. 7) Turn the MAIN ADJUST knob clockwise until you reach the voltage, current or power value desired. 8) You can monitor either the current or the power at any time by turning the METER READ knob to select the one you wish to read. B. Programmed Run 1) Turn the MAIN ADJUST knob fully counterclockwise. 2) Turn the power supply on. 3) Hold the program selector knob on SET VOLTS so that you can read the voltage limit 4) Dial in the maximum desired voltage (the voltage limit) with the PROGRAM ADJUST knob. Release the PROGRAM SELECTOR knob. 5) Turn the power supply off. 6) Set the MODE CONSTANT selector knob to CURRENT or POWER. Set the program selector knob (lower knob in right row) to RUN PROGRAM. 7) Set the correct current and voltage ranges. (The range choices are 0-5, 0-50 ma, ma (0-150 ma with 0-250OV) for current; 0-600V, 0-120OV, or V for voltage.) Note: Setting the range knobs limits the current and voltage to 105% of the ranges selected. CAUTION! Be sure you choose the correct range. To prevent thermal overload, do not operate the PS 25M in a voltage range higher than needed for your experiment See Procedure, C. Thermal Overload. 8) Connect the electrophoresis unit to the power supply using the electrode cables. 9) You can monitor either the current or the power at any time by turning the METER READ knob to select the one you wish to read. 10) Turn the power supply on. 11) Turn the MAIN ADJUST knob clockwise until you reach the desired constant current or power. C. Thermal Overload If the THERMAL OVERLOAD light comes on, you are using the PS2500 in a voltage range too high for your experiment. For example, you may be running at 200V but have the VOLTAGE RANGE set at 0-250OV. Hoefer Scientific Instruments 654 Minnesota Street* San Francisco, CA (415) (800) Instructions - PS 2500 Power Supply 3

4 1) Turn the main ADJUST knob fully counterclockwise. 2) The actual running voltage is shown in the READ VOLTAGE window. Switch the VOLTAGE RANGE knob to the correct range for the running voltage. 3) Reset the MAIN ADJUST knob to your running voltage. 3. Warranty and Liability The Hoefer PS 2500 is warranted against defects in materials and workmanship for two years from the date of the invoice. This warranty covers all parts and components of the instrument except those which are damaged or broken under the following conditions: parts and components which require frequent replacement through normal use; parts and components damaged or broken due to solvent corrosion, improper handling or use, accident or user alteration. If a problem occurs, notify Hoefer Scientific Instruments before the expiration of the warranty. See Section 4 Technical Assistance and Repair. During the warranty period, customers will not be charged for parts or labor. Hoefer Scientific Instruments will determine whether the item is to be replaced or repaired. Our instruments are designed for safety. We assume no responsibility for injury or damage if users defeat safety features or otherwise handle or use this instrument improperly. 4. Technical Assistance and Repair We offer complete technical support for all of our products. If you have questions about how to use the Hoefer product you have purchased, or need to arrange to have an instrument repaired, please call, telex or fax us at the following numbers: Ask for our Technical Service Department Toll-free Numbers: (800) or (800) Local Telephone: (415) Telex: Fax: (415) Let us know if we can help you by offering additional products or through changes or additions to our instruments. Note: Customers must call Hoefer Scientific Instruments and obtain a Return Authorization number and shipping instructions before returning instruments. Hoefer Scientific Instruments 654 Minnesota SL,, San Francisco, CA (415) (800) Instructions - PS 2500 Power Supply 4 5. Calibration Procedure

5 The PS 2500 has been designed so that the individual circuit boards can easily be replaced. Replacement boards from Hoefer have already been calibrated and no further adjustment should be necessary. If for any reason all or part of the circuit needs re-calibration, the procedure should be carried out only by a qualified technician. WARNING! Extreme care should be exercised while working around high voltage. An interlock switch in the high voltage line will open when the top panel is removed from the instrument. Allow five minutes for the capacitors to discharge before proceeding with the calibration. A. Test Equipment Required *Oscilloscope, 50 KHz horizontal, 20 mv vertical *1 Volt peak to peak square wave calibrator *Two digital volt meters (DVM) suggested, one capable of measuring 2500 volts *An external load resistance of known value between 4K and 5K, and about 400 Watts B. Preliminary Set Up 1) The dials on the front panel should be set in the following way: Meter Read: Current Current Range: 300 ma Mode: Voltage Voltage Range: volts Program Mode: Normal Program Adjust: Fully counter clockwise Main Control: Fully counter clockwise 2) Turn the power OFF and unplug the unit. Remove the top panel and the right side panel for access to circuit boards. The top panel activates the interlock switch in the high voltage line. When the panel is removed, this switch will be open. No current will flow through fuse Fl (6.25A), but current will reach the low voltage circuitry through fuse F2 (O.SA). Allow 5 minutes for the capacitors to discharge before continuing. 3) From left to right, the vertical circuit boards are labeled AlS, A2S, A3S, and A4S. Boards Fl and F2 are located on the back of the front panel, and the "mother board" on the bottom panel of the unit. 4) A jumper strip, located at center left of the A4S board, acts as a switch. It may be plugged in in two orientations. In the normal operating position, the cut off comer is located at the upper left; in the test position, at the lower right. When you open the power supply, you will find it in the normal operating position. 5) The test point socket is located at the center right of the A4S board. Test points are numbered in a counter clockwise direction from the notch at the top of the socket. Point 8 is the ground. Hoefer Scientific Instruments 654 Minnesota SL o San Francisco, CA (415) (800)

6 Instructions - PS 2500 Power Supply 5 D. Calibration Steps Common To Voltage, Current, and Power Modes 1) Turn the power ON and allow 5-10 minutes warm up time. 2) Zero adjustments for voltage, current and power meter readings are set by means of potentiometers located in a row along the top of circuit board A4S. Potentiometer P13 sets the zero level for voltage, P12 for current, and P9 for power. Insert an alignment tool into the slot of the appropriate potentiometer and rotate it until the corresponding meter on the front panel reads zero. To adjust the zero setting in the power mode, note that you must first change the METER READ setting from CURRENT to POWER. 3) Turn the power OFF and return the MAIN ADJUST knob to a fully counterclockwise position. E. Calibration Of Voltage Mode Circuitry 1) To adjust the zero setting for the voltage sense amplifier, place the jumper strip in the test position, with the marked comer down. Connect a digital voltmeter (DVM) to Test Point 2 (T.P.2), with the reference circuit ground (T.P.8). Turn power ON and adjust potentiometer P4 for a reading close to zero at T.P.2. 2) Turn the power OFF and close the interlock switch by taping or clamping the button down. Return the jumper strip to the Operate position, with the marked comer up. 3) To set the gain of the voltage sense amplifier in each voltage range, connect a DVM at T.P.2, with the reference ground, and a second DVM, capable of measuring 2500 volts, to the Output on the front of the power supply. (If you have only one DVM, you will have to shift it back and forth.) a. With the voltage range set at volts, turn the power ON and turn the MAIN ADJUST knob until the DVM at T.P.2 reads 10 volts. b. Adjust potentiometer Pl on board A4S to give 603 volts at the output Return the MAIN ADJUST knob to its fully counterclockwise position. c. Set the voltage range at V and turn the MAIN ADJUST knob until the DVM at T.P.l reads 10 volts. d. Adjust potentiometer P2 on board A4S to give 1200 volts at output. Then return the ADJUST knob to its fully counter clockwise position. e. Set the voltage range at volts. Adjust the MAIN ADJUST knob to give 10 V at T.P.2, and adjust potentiometer P3 on board A4S to give 2400 volts at output. 4) To adjust the span of the panel volt meter, remove the cover from the volt meter on the front panel of the power supply. In the lower right-hand comer of the meter you will see a small adjustment screw. With the MAIN ADJUST knob set to give 2400 volts at output (preceding step), rotate this screw until the panel meter reading exactly corresponds with that shown by the DVM at the output. 5) Return the MAIN ADJUST knob to its fully counterclockwise setting. Hoefer Scientific Instruments 654 Minnesota St. * San Francisco, CA (415) (800) SO

7 Instructions - PS 2500 Power Supply 6 F. Calibration Of Current Mode Circuitry 1) As in the calibration of the voltage mode circuitry, the jumper strip on circuit board A4S should be in the Operate position, with the marked comer up, and the interlock switch should be closed. Set the current range at 0-50 ma and the voltage range at 0-120OV. 2) To adjust the zero setting for the current sense amplifier, connect a DVM at T.PA, with reference ground (T.P.8). Turn the power ON and adjust potentiometer P5 on board A4S to give zero volts at T.P.4, with no load at the output. 3) Connect a load of known resistance (4K to 5K) to the output terminals. Connect a DVM across the second set of output terminals. Calculate the voltage needed to give 50 n-la current through the known load resistance (E/RL = 50 ma). Adjust the ADJUST knob until the DVM at output shows the calculated voltage. 4) Adjust potentiometer P6 to give V as indicated on the DVM at T.P.4. This represents a full scale gain on the current sense amplifier. 5) Return the MAIN ADJUST knob to its fully counterclockwise setting. G. Power Mode Circuitry Calibration 1) To calibrate the Power Mode, the jumper strip should be in the Test position with the cut-off comer at the lower right side. Turn the power OFF and open the interlock switch. Then allow five minutes before touching the jumper strip. 2) Connect a square wave calibrator signal to T.P3 on board A4S with reference to signal ground (T.P.8). This test point corresponds to the X input to multiplier U4. Also connect the signal ground, i.e. T.P.8, to T.P.5, which corresponds to the Y input to U4. 3) Connect an oscilloscope to T.P.12, and set the oscilloscope at 20 mv/cm. Turn the power ON and adjust potentiometer P7 to give a minimal signal at T.P.12. 4) Reverse the square wave calibrator, connecting the signal to T.P.5 (Y input), and the signal ground to T.P.3 (X input). Adjust potentiometer P8 to give a minimal signal on the oscilloscope at T.P.12. 5) Remove the connections made in the previous three steps. Connect the signal ground (T.P.8) to both T.P.3 and T.P.5 together. Connect a DVM at T.P.12, and adjust potentiometer P9 to give zero volts at T.P.12. 6) Remove the connections made in the previous step. To calibrate the multiplier gain, connect a DVM at T.P.6. Turn the PROGRAM ADJUST knob clockwise until the DVM reads volts. 7) Remove the DVM. Connect T.P.6, now set at volts, to both X and Y inputs (T.P.2 and T.P.5). 8) Connect a DVM at T.P.12. Adjust potentiometer PIO to give volts at T.P.12. Hoefer Scientific Instruments 654 Minnesota SL,, San Francisco, CA (415) (SW) Instructions - PS 2500 Power Supply 7

8 9) Repeat Steps 5 and 8 of this section, resetting potentiometers P9 and P10, in order to calibrate the interaction between the zero adjustment and the gain adjustment. H. Meter Span Adjustment for Current/Power 1) Set the current range to ma. Turn the MALN ADJUST knob until the DVM at output reads 1000 V. Calculate the current produced by 1000 volts through the known load resistance. Remove the cover from the panel current-power meter, and rotate the small screw in the lower right-hand comer of the meter until the panel meter reading corresponds exactly to the calculated current. 2) Set the METER READ knob on the front panel to POWER. Adjust potentiometer Pll to obtain the same reading on the panel meter as in the previous step. 6. Ordering Information To place your order or to obtain part number and price information, please call, telex or fax us at the following numbers: Ask for our Order Department To order by mail, please send your purchase order to the following address: Toll-free Number (800) or (800) Local Telephone: (415) Telex: Fax: (415) Order Department Hoefer Scientific Instruments Post Office Box San Francisco, CA If you would like assistance in choosing the most suitable instrument for your research needs, please ask for our Technical Service Department. Hoefer Scientific Instruments 654 Minnesota Street. San Francisco, CA (415) (800)

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