SOLID STATE DIGITAL TIMER

Transcription

1 INSTRUCTION MANUAL For SOLID STATE DIGITAL TIMER MODEL SST-2 SERIAL NO. It is essential that this instruction book be read thoroughly before putting the equipment in service.

2 APPRECIATION We are indebted to those who have given their time and advice in the preparation of this instruction manual. It is MULTI-AMP Corporation's goal to continually improve its products and services to its customers. To that end, we welcome any suggestions or contributions our customer would care to offer. IMPORTANT The information and data contained within this instruction manual are proprietary with AVO MULTI-AMP Corporation. The equipment described herein may be protected by one or more U.S. letters patent. AVO MULTI-AMP specifically reserves to itself all rights to such proprietary information as well as all rights under any such patent, none of which is waived by the submission of this instruction manual to anyone. The recipient, if a Government agency, acknowledges that this instruction book and the equipment described were procured with "Limited Rights" to technical data as described in ASPR (b). Copyright AVO MULTI-AMP Corporation, 1975, 1978, 1987, 1989, 1990, 1992 Table of Contents Section Page

3 INTRODUCTION SAFETY PRECAUTIONS... 1 THEORY OF OPERATION... 2 Description of Controls... 2 INPUT VOLTAGE SELECTION... 4 Models With Input Selector Switch... 4 Models With Input Autotransformer... 4 Models Without Input Autotransformer... 5 PREPARATION FOR OPERATION... 6 Circuit connections... 6 Control Selection... 6 Timing Functions... 6 TEST PROCEDURES... 8 General Test Procedures... 8 SERVICE DATA... 9 Servicing... 9 Service and Repair Order Instructions Preparation for Reshipment Warranty Statement REPAIR DATA Basic Troubleshooting Power Input Chassis Assembly Timer Assembly Timing Errors Connection Point Identification Guide Wire Color Code Guide Parts Replacement PARTS LIST Model SST-2 Digital Timer PARTS LIST Part No. 3710A Timer Assembly ii

4 INSERT SCHEMATIC DRAWINGS Drawing No C, Figure 1 Model SST-2 With Autotransformer Drawing No C, Figure 2 Model SST-2 Without Autotransformer Drawing No C, Figure 3 Model SST-2 With Input Selector Switch Drawing No D Part No. 3710A Timer Assembly iii

5 SAFETY PRECAUTIONS WARNING The Multi-Amp Model SST-2 Timer is designed for use on energized circuits. For the safety of the operator and protection of the instrument, do not connect it to circuits that have voltages present beyond the limits of operation stated in the specifications. This includes circuits that could become energized during the course of a test procedure utilizing this instrument. CAUTION The input voltage of this instrument is selectable. All the units are shipped from the factory set up for operation from a nominal 115 volt source. If this unit is to be used on a 230 volt source, refer to the INPUT VOLTAGE SELECTION section for proper instructions. For safe operation, it is absolutely essential that the operator properly and effectively ground (earth) the test set. This is accomplished by connecting the input line cord to a properly grounded receptacle. The test leads provided with the Model SST-2 are sufficiently insulated to withstand any voltage encountered within the specified operating voltages of the instrument as stated in the specifications. For the safety of the operator, if test leads of another type or manufacture are used, the insulation rating and quality should be at least equal to that of the leads provided. 1

6 THEORY OF OPERATION Description of Controls This section of the instruction manual describes the functions of all the various control switches, etc., which are located on the front panel of the Model SST-2. All controls are clearly marked and logically grouped so that continual reference to the instruction manual should not be necessary after the operator has become acquainted with the operation of the instrument. Input Cord Input Power POWER ON/OFF Switch Fuse F1 Timer Display RESET Button SEC/HZ Switch A line cord with a standard three-prong grounded plug is provided for connection of the timer to a suitable source of power. Each Model SST-2 is shipped from the factory with the input power set up for 115 volt (±10%) operation. Should it be desired to change this timer to operate from a 230 volt (±10%) source of supply, refer to the INPUT VOLTAGE SELECTION Section for details. Used to energize the power input of the timer. Protects the input power system of the timer. Illuminates whenever the power input to the timer is energized, and indicates elapsed time. Resets timer logic and resets display to zero. Selects mode of count, either in cycles or seconds. NOTE: The timer will not stop when the maximum count of any range is reached. It will roll over to zero and continue counting. If the timer is observed carefully, timing beyond maximum range can be performed..01/.0001 Switch Selects the range of the seconds mode, either 0.01 to seconds or to seconds. NOTE: Never change the SEC/Hz or.01/.0001 switch positions during a timing operation or an error will result. START Binding Posts The start signal selected by the START Selector Switch is applied to these binding posts. 2

7 STOP Binding Posts START LATCH ON/OFF Switch STOP LATCH ON/OFF Switch START/STOP Selector Switches The stop signal selected by the STOP Selector Switch is applied to these binding posts. This two position switch is used in conjunction with the START Selector Switch and START Binding Posts to control the starting of the counter. When "ON", the START LATCH allows timing to be initiated by any start gate and to be stopped only by the stop gate selected with the STOP Selector Switch and applied at the STOP Binding Posts. When "OFF", the START LATCH allows timing to be initiated by any start gate and to be stopped when the start gate is reversed (such as timing the closing and opening of a single contact when measuring the trip-free operating time of a circuit breaker). This two position switch is used in conjunction with the STOP Selector Switch and STOP Binding Post to control the stopping of the counter. When "ON", the STOP LATCH allows timing to be stopped at the first operation of any stop gate (thus ignoring contact bounce, for example). When "OFF", the STOP LATCH allows timing to be stopped by any stop gate and then restarted if the stop gate reverses (provided the start gate is still energized) and then again stopped when the stop gate is again energized. Two identical, independent, four-position switches are provided for selection of start and stop gates. The left switch is used to select the start gate operating mode while the right switch is used to select the stop gate mode. The following modes are provided for both the start gate and the stop gate. a. Dry Contact Closure (N.O. DRY CONTACTS). Timer starts or stops at the closure of a normally open contact or upon conduction through a semi-conductor device such as a scr, triac or transistor. b. Dry Contact Opening (N.C. DRY CONTACTS). Timer starts or stops at the opening of a normally closed contact or when conduction through a semi-conductor device such as a scr, triac or transistor is interrupted. c. Application of AC or DC Potential (AC/DC APPLIED). Timer starts or stops when an AC potential (3-300 volts rms) or DC potential (5-300 volts) is applied. d. Removal of AC or DC Potential (AC/DC REMOVED). Timer starts or stops when an AC potential ( volts rms) or DC potential (5-300 volts) is removed. 3

8 INPUT VOLTAGE SELECTION All Model SST-2 timers are manufactured as dual voltage (115/230V) units and are shipped from the factory with the input voltage set for nominal 115 volt operation. When it is desired to operate the Model SST-2 from a nominal 230V power source, it is necessary for the operator to change the input voltage by one of three different methods, depending upon the age of the SST-2. The newest model uses a selector switch (see Models with Input Selector Switch). Earlier Model SST-2 timers were built with the voltage selection made directly to the timer assembly by moving a wire at the terminal block (TB1). Later models have an input autotransformer to provide more power for the auxiliary relay and to standardize the timer assembly that is used. If the transformer is present, DO NOT change any of the connections at the terminal block. Since all new units shipped from the factory are connected for nominal 115V operation, a ½ ampere fuse is installed in the input fuse holder. If the input voltage tap is changed for 230V operation, it is necessary to replace the ½ ampere fuse with a ¼ ampere fuse. The reverse procedure is necessary when converting from 230V operation to 115V operation. Five spare fuses of each current rating are supplied with each new unit. The following procedures are provided for changing the input voltage of the Model SST-2. There is a procedure for each of the three types of input power systems described above. Models With Input Selector Switch Refer to Schematic Drawing 15498C, Figure 3, Section VI. The Input Selector Switch is located in the front left corner of the lead compartment. To change the input voltage of the unit, remove the instrument from the enclosure by removing the four mounting screws located on the back of the enclosure and slide the instrument out until the switch is accessible. Insert a screwdriver blade in the slot of the voltage selector and move it to the desired position. The voltage selected is marked on the recessed area of the selector. Slide the instrument into the enclosure and install the four mounting screws. Insert the correct amperage fuse in the fuse holder for the input selected. Models With Input Autotransformer Refer to Schematic Drawing 15498C, Figure 1, in Section VI. To change the input voltage of the unit, remove the instrument from the enclosure by removing the four mounting screws located on the back of the enclosure and slide the instrument out. Locate the autotransformer mounted adjacent to the timer assembly enclosure. A terminal strip is attached to one of the transformer mounting screws. There are two wires, one black and one black with red tracer, connected to one terminal. This is the 115V tap. The red wire connected to another terminal is the 230V tap. There is a jumper connected between a terminal with a brown wire (common) and the 115V tap. This is referred to as Connection "A" for 115V operation. 4

9 To convert the unit to 230V operation, disconnect the jumper from the 115V tap (terminal with one black wire and one black wire with red tracer), and reconnect the jumper to the 230V tap (terminal with red wire). This is referred to as Connection "B" for 230V operation. To convert the unit back to 115V operation, simply reverse the procedure by moving the jumper to the 115V tap (Connection "A") as described above. Return the instrument to the enclosure and install the four mounting screws. Insert the correct amperage fuse in the fuse holder for the input selected. Models Without Input Autotransformer Refer to Schematic Drawing 15498C, Figure 2, in Section VI. To change the input voltage of the unit, remove the instrument from the enclosure by removing the four mounting screws located on the back of the enclosure and slide the instrument out. Locate the black wire and gray wire (from the Timer Cable #1) which terminate at the left side of the terminal block (TB1) located on the right side of the chassis (when viewing the unit from the back). The black wire is the 115V tap and the gray wire is the 230V tap. The black wire on the right side of TB1 is connected opposite of the black wire on the left side of TB1 for 115V operation and is referred to as Connection "A" (See CAUTION note). To convert the unit to 230V operation, disconnect the black wire on the right side of the terminal block and connect it to the terminal on the right side of the terminal block opposite the gray wire. This is referred to as Connection "B" for 230V operation. To convert the unit back to 115V operation, simply reverse the procedure by moving the black wire back to the 115V tap (Connection "A") side which is described above. Return the instrument to the enclosure and install the four mounting screws. Insert the correct amperage fuse in the fuse holder for the input selected. CAUTION There may be two wires present at the terminal on the right side of the terminal block on very early models. If they are both black, disconnect both wires and separate them. Using an ohmmeter, check continuity between the black wire terminating at the fuse holder (F1) and one of the two black wires that have been disconnected. The one that reads continuity is the wire that is to be moved. Mark this wire for future reference. Regardless of color, the other wire is a relay wire and must remain terminated opposite the black wire on the left side of the terminal block. 5

10 PREPARATION FOR OPERATION Circuit connections Test all circuits the SST-2 START/STOP Binding Posts are to be connected to. If dry contact operation is to be used, be sure the circuit will not become energized when the device to be tested operates. If energized contact operation is to be used, be sure that voltage levels that are or will be present on the test circuits will not exceed the rating of the instrument. The voltage levels present must also be within the operating range of the START/STOP circuits or a timing error will result. The test leads provided are sufficiently insulated for test voltages within the specifications of the instrument. Control Selection The Model SST-2 provides a wide variety of timing functions. The operator must determine what type of timing conditions will be presented and select the appropriate functions that will permit the Model SST-2 to perform the desired tests. This can be best accomplished if the operator is thoroughly familiar with the various functions of the unit prior to its use by reviewing the Description of Controls and the Timing Functions sections of the manual. Timing Functions The timing functions are explained in the Operating Procedures and Description of Controls. However, they can be best understood by the following method: 1. Connect the input line cord to the correct power source. 2. Connect one pair of test leads to the START Binding Posts and one pair to the STOP Binding Posts. 3. Select the N.O. DRY CONTACTS position with the START and STOP Selector Switches. 4. Select any timer mode and range desired. 5. Switch both the START and STOP LATCH Switches to the OFF position. 6. Switch the POWER ON. The timer display will light. 7. Press the timer RESET Button. NOTE: Always reset the timer prior to beginning a timing test. This is especially important when any control functions are changed. 8. Touch the START test leads together to start the timer. Separate them and the timer will stop. The timer will continue to start and stop every time the START test leads are touched together and separated. NOTE: The STOP gate will not stop the timer with above control selections. 9. Put the START LATCH Switch in the ON position. 10. Reset the timer. 6

11 11. Touch the START leads together and then separate them. The timer will continue to run. 12. Touch the STOP leads together. The timer will stop. Separate the STOP leads. The timer will remain stopped. 13. Touch the START leads together. The timer will restart and continue counting until the STOP leads are again touched together. 14. Stop the timer. 15. Put the STOP LATCH in the ON position. 16. Reset the timer. 17. Start the timer by momentarily touching the START test leads together. The timer will start and continue to run. Momentarily touch the STOP test leads together. The timer will stop. Attempt to restart the timer without pressing the RESET button. The timer will remain stopped. 18. Reset the timer and repeat the test. This selection will provide starting and stopping from momentary contact closure. 19. Put the START LATCH in the OFF position. 20. Reset the timer. 21. Repeat the test as described in Step 8. Even with the STOP LATCH in the ON position, the STOP gate will not stop the timer. Steps 1-21 demonstrate all the basic starting and stopping functions of the Model SST-2. The N.C. DRY CONTACTS selection functions opposite of the N.O. DRY CONTACTS selection. Rather than touching the leads together to start or stop the timer they are separated, simulating a closed contact moving to the open position. Similarly, AC/DC APPLIED acts like an open contact moving to the closed position, and AC/DC REMOVED acts like a closed contact moving to the open position. Experiment with the different START/STOP functions and various combinations of them, including the LATCH functions, to fully understand what the timer will do in a desired test situation. It is important to note that incorrect timer functioning during a test is generally caused by either an incorrect control selection, not resetting the timer prior to initiating the test or not properly identifying the control points used in the test scheme. 7

12 TEST PROCEDURES There are literally hundreds of testing applications for the Model SST-2. There are 48 control function combinations and three timer mode selections. Once the operation of the Model SST-2 is thoroughly understood, the operator can easily construct a test procedure for each application encountered. Various procedures could be suggested by Multi-Amp, but the correct method of timing various devices depends entirely on the recommendations of the manufacturer of the device and the preferences of the operator or the organization that sets the standards for performing such tests. Therefore, a General Test Procedure has been provided to guide the operator. It is recommended that the operator add appropriate test procedures to the Test Procedures section as each situation is encountered. If various specific or standard procedures are already available, adding copies of them to the Test Procedures Section for convenient field reference is suggested. General Test Procedures Refer to all cautionary statements and other instructions prior to making any test connections. 1. Connect the instrument to a suitable source of power. Refer to the Input Voltage Selection section for details. 2. Switch the POWER ON/OFF Switch ON. The timer display should light. 3. Switch the START Selector Switch to the desired position for the START function to be used. 4. Switch the START LATCH ON/OFF Switch to the desired position. If it is desired to use a separate STOP function to stop operation of the timer, switch the START LATCH ON. If it is desired to use the reversal of the START signal to stop the timer (such as timing the closing and opening of single contact when measuring the trip-free operating time of a circuit breaker), switch the START LATCH OFF. 5. When it is desired to use a separate stop gate signal to stop the timer, switch the STOP Selector Switch to the desired position. 6. Switch the STOP LATCH ON/OFF Switch to the desired position. If it is desired to have the timer stop upon the first stop signal only, switch STOP LATCH ON. If it is desired to have the timer restarted if the stop signal reverses (as when measuring contact bounce), switch STOP LATCH OFF. 7. Switch the SEC/HZ Switch to the desired mode. If the seconds mode is used, switch the 0.01/ Switch to the desired range. 8. Make necessary connections to the START and STOP Binding Posts. 9. When the appropriate start and stop signals are applied, the display indicates the elapsed time of the test. NOTE: Always reset the timer before each timing test to assure all logic circuits are in the correct state, even when the display reads zero. This is especially recommended when any switch positions are changed. 8

13 SERVICE DATA Servicing The timer utilizes straightforward circuits and components which require little or no service except for routine cleaning, tightening of connections, etc. The timer should be serviced in a clean atmosphere away from energized electrical circuits. The following maintenance is recommended: 1. Open the unit every six months and examine for: a. dirt b. moisture c. corrosion 2. Remove dirt with dry, low pressure, compressed air. 3. Remove moisture as much as possible by putting the test set in a warm, dry environment. 4. As corrosion may take many forms, no specific recommendations can be made for its removal. 9

14 Service and Repair Order Instructions If factory service is required or desired, contact the factory for return instructions. A Repair Authorization (RA) number will be assigned for proper handling of the unit when it arrives at the factory. If desired, a letter with the RA number and instructions can be provided. Provide the factory with model number, serial number, nature of the problem or service desired, return address, your name, and where you can be reached should the factory need to contact you. If desired, you may also provide a purchase order number, cost limit, billing, and return shipping instructions. National Institute of Standards and Technology (NIST) traceable calibration and certification of two types is available, if desired, at additional cost. Class One: Class N: A certificate is provided verifying the traceability and calibration of the equipment. That which is required for nuclear power plants. A certificate of traceability and calibration along with "as found" and "as left" data are provided. If an estimate is requested, provide the name and contact information of the person with approval/disapproval authority. Pack the equipment appropriately to prevent damage during shipment. If a reusable crate or container is used, the unit will be returned in it if it is in suitable condition. Put the RA number on the address label of the shipping container for proper identification and faster handling. NOTE: Ship the equipment without instruction manuals or nonessential items such as test leads, spare fuses, etc. These items are not needed to conduct repairs. Preparation for Reshipment Save the shipping container for future use. The shipping container your unit came in is designed to withstand the normal bumps and shocks of shipping via common commercial carrier. For example, you may wish to reship your unit to Multi-Amp for annual calibration certification. 10

15 Warranty Statement Multi-Amp Corporation warrants to the original purchaser that the product is free of defects in material and workmanship for a period of one (1) year from date of shipment. This warranty is limited and shall not apply to equipment which has damage, or cause of defect, due to accident, negligence, improper operation, faulty installation by the purchaser, or improper service or repair by any person, company or corporation not authorized by Multi-Amp Corporation. Multi-Amp Corporation will, at its' option, either repair or replace those parts and/or materials that it deems to be defective. Any costs incurred by the purchaser for the repair or replacement of such parts and/or materials shall be the sole responsibility of the original purchaser. THE ABOVE WARRANTY IS IN LIEU OF ALL OTHER WARRANTIES, EITHER EXPRESSED OR IMPLIED ON THE PART OF THE MULTI-AMP CORPORATION, AND IN NO EVENT SHALL THE MULTI-AMP CORPORATION BE LIABLE FOR THE CONSEQUENTIAL DAMAGES DUE TO THE BREACH THEREOF. 11

16 REPAIR DATA It is not always necessary to return the complete instrument to the factory for repair. To save time and reduce costs, basic troubleshooting information has been provided to guide the technician to the possible source of a problem. At least half of all problems experienced with the Model SST-2 are minor and can be corrected with a single replacement part. More extensive problems can be corrected by replacing printed circuit board assemblies in the timer assembly. Repairs beyond the scope of the troubleshooting guide should be referred to the Service Department at Multi-Amp or handled through the Multi-Amp Representative. If the unit is still within the original warranty period, or limited warranty period following factory servicing, the factory must be contacted before attempting any repairs or the warranty will be void. The troubleshooting information relies on the schematic drawings provided with this manual and are normally sufficient for this purpose. Be advised that the drawings are applicable to the unit the manual was supplied with at the time of purchase. If the instruction manual was obtained separately, the drawings will be applicable to the equipment in production at that time and may not duplicate the unit being repaired. It is recommended that if a difference between the unit and the drawings exists, the technician should contact the factory before attempting repairs. Provide the Multi-Amp part number for the part or assembly in question and the serial number of the SST-2 when making inquiries. Two guides in this section are provided to assist the technician in following the schematic drawings. The Wire Color Code Guide identifies the color codes used on the drawings that correspond to the wiring in the unit. The Connection Point Identification Guide identifies the connection points and input circuit functions of drawing 15354D. The guides should be reviewed before using the schematics. Basic Troubleshooting WARNING It is necessary to energize the SST-2 to properly troubleshoot some parts of the circuitry. The technician must take all applicable safety precautions for working on energized circuits. NOTES Before suspecting a failure in the instrument, review the Timing Functions, Description of Controls and Timing Variables sections to ensure that the problem is not a result of operating error. Preliminary testing of the SST-2 within its specified limits can help determine if a malfunction actually exists, identify the type of malfunction and define the general area of the failure. Failures often occur from components simply wearing out from use. This of course is normal, but occasionally they wear out prematurely or fail as a result of conditions occurring during operation of the instrument. Common causes of malfunctions, other than improper operation, are incorrect power input (voltage above or below specified limits), incorrect test signal voltages (outside of the specified AC/DC Applied/Removed limits), and contact or circuit resistance too great for the Dry Contact gates to operate properly. These causes can affect either chassis assembly parts, timer assembly parts, or both. Power Input 12

17 Input voltage affects the whole unit and may or may not cause permanent damage if voltage is incorrect. These problems can often be corrected by simply using a better source of input power. The rated voltage limits are to 126.5V for the nominal 115V tap and 207 to 253V for the nominal 230V tap, 50 or 60 HZ. Some symptoms are as follows: 1. Low voltage: Weak display, latch relay is sluggish, Start/Stop gates function erratically, timing inconsistent, fuses fail. Low voltage problems are more obvious on 50 HZ systems. 2. High voltage: Varistor failure, timer assembly power supply failure, input autotransformer failure. Chassis Assembly Refer to Schematic Drawing 15498C and Wire Color Code Guide. Basic troubleshooting of the main chassis and front panel components are as follows. Problems caused by a malfunction in the timer assembly will be covered separately. 1. No power: Check power source, input fuse, line cord, voltage at autotransformer, power switch, wiring and connections at TB1. 2. Start/Stop Latch malfunction: Auxiliary relay contacts dirty or relay defective, varistor failure, latch switch failure (Notes: Latching occurs with switch contacts open). 3. Start/Stop function problems: START and/or STOP Selector Switch faulty, dirty contacts, broken jumpers or wiring, bad connections, resistor failure. Timer Assembly Refer to Schematic Drawing 15354D, Wire Color Color Code and Connection Point Identification Guide. If all the items external of the timer assembly are in proper order, then the problem exists within the timer assembly itself. The P/N 3710A Timer Assembly is constructed of five basic parts: 1. Timer Start/Stop PCB Assembly (P/N 4121) 2. Logic PCB Assembly (P/N 4190) 3. Display PCB Assembly (P/N 4192) 4. Mother PCB Assembly (P/N 4191) 13

18 5. Timer Enclosure (which includes the input transformer, voltage regulator and lens/bezel assembly). NOTE: The onboard timer assembly transformer is also designated T1 and is not to be confused with the chassis autotransformer. The complete timer assembly can be removed from the front panel of the SST-2 by disconnecting Cables #1 and #2 from the terminal strips, removing the four screws in the display panel and lifting the timer out from the back side of the front panel. It is usually recommended that the complete timer assembly be returned for factory repair if found to be defective. Then any improvements that have been made in the assembly can be incorporated into it during repair and servicing. Some basic troubleshooting can pinpoint problems to the approximate cause, if it is desired to repair the P/N 3710A on site. Basic troubleshooting is as follows: 1. No display when the SST-2 is energized: Power supply failure, defective display IC's, defective components on or connections to P/N 4192 PCB. See Power Supply malfunctions. 2. Weak or defective display: Poor supply voltage, defective display(s), defective components on P/N 4192 PCB. See Power Supply malfunctions. 3. Problems with SEC/HZ or.01/.0001 range selection: Defective selector switch(es), defective circuit resistors or defective IC's on P/N 4190 PCB or P/N 4192 PCB. 4. Problems with timer reset: Defective pushbutton switch on P/N 4192 PCB or defects in P/N 4190 PCB. 5. Counting problems: a. Counting errors in seconds but not cycles or vice versa: Defects in P/N 4190 PCB. b. Counting errors in seconds only: Defective IC 33-35, TR4 or related parts on P/N 4191 PCB, defective IC 32 or 37 on P/N 4121 PCB, T1 failure, defective 16MHz oscillator (IC13). Read counting frequency at pin 11 on IC13. c. Counting errors in both seconds and cycles: Defects in P/N 4121 Start/Stop PCB, defects in P/N 4190 PCB. 6. Latch malfunctions: Note: The latch relay (X1) is controlled by the timer assembly. Therefore, relay malfunctions can be caused by timer malfunctions. a. Latch relay (X1 on chassis) not functioning: Defective relay (X1), defective triac (TR5), or relay (IC36) on P/N 4191 PCB. 14

19 b. No Start/Stop Latch: Defective TR5 or IC36, diode D30, defects on P/N 4190 PCB. c. No Start Latch only: Defective IC18, or related parts P/N 4190 PCB. d. No Stop Latch only: Defective components, P/N 4190 PCB. 7. Start/Stop malfunctions: a. All Start modes malfunction: Defective IC24 on P/N 4121 PCB, reset failure, stop mode failure. b. All Stop modes malfunction: Defective IC27 on P/N 4121 PCB, reset failure. c. AC/DC Applied/Removed Start malfunction: Defective D11-14, IC26 on P/N 4121 PCB. d. N.O./N.C. Dry Contact Start malfunction: Defective R47, D9, D11-18, IC25 on P/N 4121 PCB, T1 failure. e. AC/DC Applied/Removed Stop malfunction: Defective D21-24, IC29 on P/N 4121 PCB. f. N.O./N.C. Dry Contact Stop malfunction: Defective R48, D19, D25-28, IC28 on P/N 4121 PCB, T1 failure. g. N. O. Dry Contacts Stop and AC/DC Applied Stop malfunction: Defective IC's on P/N 4121 PCB. 8. Power Supply malfunction: Various outputs of T1 supply a variety of functions in the timer assembly. Partial failure of the output will result in loss of some or all timer functions. a. No display: Loss of T1 input winding, loss of 160V output or D1-D4, R32 (180V DC), loss of 8V output, D5-D8, VR-1, (5V DC) related parts. b. Loss of timer Start (includes seconds count): Loss of 14V output of T1, or defective bridge circuit. c. Loss of timer Stop: Loss of 14V output of T1, or defective bridge circuit. NOTE: There are two 14V windings. See Connection Point Identification Guide for the appropriate 14V output. 15

20 Timing Errors AC applied or removed Start/Stop signals can create what appears to be poor repeatability, an inaccuracy or a malfunction in the timer. The lower the voltage level, the more serious the "error" will be. What appears to be an error, however, is actually a variation in the point on the sine wave at which the voltage is great enough to cause the gate circuit to operate. If the circuit used for the timing test is a low AC voltage and the point at which the contact in the test circuit opens or closes is at or close to zero on the sine wave, the period of time before the voltage level is high enough to trigger the gate circuit can be as much as 4 milliseconds and the total timing variation can be as much as 8 milliseconds. The shorter the duration of the timing test, the more significant the variation becomes. Therefore, if small timing variations would present a problem, it is recommended that an AC voltage of 115 volts or above or a DC voltage be used for voltage applied/removed test selections. When the SST-2 is being calibrated, the AC voltage variable is often overlooked. This is particularly true when the timer is compared to a counter and the two are triggered simultaneously with an electronic switch. For best results, a DC voltage should be used to eliminate the variable. If testing the AC voltage Start/Stop characteristics is desired, then the Start/Stop signal must be triggered at the same point on the sine wave to assure that the gate signal will be repeatable. Ideally, the signal should be at a point near peak in the positive direction. In addition, the specified rms AC voltage values for the various Start/Stop control selections must be adhered to. If a timing error or variation persists after all the suspected causes of error have been eliminated, then it is fairly certain the timer is malfunctioning. Connection Point Identification Guide The following information will provide a guide to finding faulty circuitry and components in the P/N 3710A Timer Assembly using Schematic Drawing 15354D. It also identifies circuit functions of the connections made at TB1 and TB2 on the chassis assembly. 1. Connection Point Identification: Numbers or letters in squares correspond to either connector terminations on P/N 4191 PCB (matching edge points on P/N 4121 and 4190 PCBs) or soldered connections on P/N 4192 PCB. The numbers and letters in circles correspond to soldered connections on P/N 4191 PCB. Wire colors followed by 1 or 2 (example: BE2) correspond to Cables #1 and #2. 2. Connection and Component Location: The upper one third of the drawing (point "F" and above) including all components in the area of ICs are associated with P/N 4121 PCB. The three switch diagrams (S1A, S2A, and S3A) in the middle portion of the drawing are part of switches S1, S2 and S3 shown in the lower right area of the drawing. These switches and ICs 1-11 are located on P/N 4192 PCB. All other items in the area of ICs are on P/N 4190 PCB. Components near TR4, TR5, and ICs are mounted on P/N 4191 PCB. The components associated with T1 and VR-1 are mounted on the timer assembly enclosure. 16

21 3. T1 Transformer Input (supplied by Cable #1): GY1: not used (older models, 230VAC tap) BK1: 115VAC W1: neutral (or common) AC GN1: input ground (earth) 4. T1 Transformer Output: BE1 to V: 14V (cycles time base and N.O./N.C. Dry Contact Start) W-V to BE2: 14V (N.O./N.C. Dry Contact Stop) R to R: 8V (to VR-1 for 5VDC logic voltage supply) O to O: 160V (for +180VDC display voltage supply) NOTE: Voltages given above for T1 are nominal values. 5. Functions of Circuits from Cables #1 and #2 to P/N 4121 PCB. O1 to Y1: AC/DC Applied/Removed Start Y2 to O2: N.O./N.C. Dry Contact Start BN1 to BE1: AC/DC Applied/Removed Stop BE2 to BN2: N.O./N.C. Dry Contact Stop R1 to V1: Latch relay (X1) coil circuit switcher NOTE: The following circuits reference to GN2 chassis ground for operation. V2: N.C. Dry Contact Start and AC/DC Removed Start R2: Start Latch BK2: Stop Latch GY2: Latch circuit switcher control W2: N.O. Dry Contact Stop and AC/DC Applied Stop 6. Cycles Time Base: The time base for the cycles mode is provided by IC's and TR4 from a voltage supplied by T1 at input line frequency. The 60HZ and 600HZ values shown are 50HZ and 500HZ for a 50HZ input power line frequency. Wire Color Code Guide W - White R - Red Y - Yellow V - Violet P - Pink A - Azure (light blue) BK - Black BE - Blue GY - Gray O or OR - Orange T - Tan A combination of the above colors may be used to identify one wire. Examples are as follows: Two colors: Three colors: W - V means it is a white wire with a violet tracer (thin stripe). WGN - BK means it is a white and green wire of evenly divided colors with a black tracer. 17

22 Parts Replacement The parts in the chassis assembly of the SST-2 can be replaced without effecting the accuracy or functions of the unit. Any components that are shown on the drawing that are not present in the SST-2 being serviced should have those components added to the unit. If the SST-2 does not have an autotransformer, one should be installed. All present P/N 3710A Timer Assemblies are 115V input only. If the complete timer assembly is replaced, the SST-2 can only be operated at 115V input unless the autotransformer is installed. When installing the autotransformer and the existing P/N 3710A is to be used, connect the P/N 3710A for 115V and select the desired input voltage to the SST-2 at the autotransformer. Order modification kit P/N 8667, which includes all parts necessary for this improvement and Assembly Drawing 20377D. The autotransformer makes it possible to modify the SST-2 for front panel, switch-selectable input voltage as well. If it is desired to do so, contact the factory for guidance or have the modification installed at the factory. The X1 relay should be replaced and the V1 varistor added in the older models. Later models with the autotransformer that do not have the V1 varistor should have it added to the X1 relay. The printed circuit board (PCB) assemblies can be replaced without affecting timer accuracy or functions. However, component replacement can cause problems if the revision number of the PCB is not clearly identified. To avoid possible problems with component replacements, it is strongly recommended that the PCB assemblies be returned to the factory for proper repair, testing and updating. 18

23 PARTS LIST Model SST-2 Digital Timer Description Part No. Schematic Drawing C Digital Timer Assembly 1/ A Binding Post, red Binding Post, yellow Line Cord, 3/C with cap Enclosure with Lid 2/ Relay, 3PDT Knob, bar type Switch, rotary (start/stop selectors) Switch, 2PDT toggle (power on/off, start/stop latch) Fuse Holder Autotransformer, input 3/ Resistor, 1.5k ohm Varistor 3/... XS173 Terminal Block, 10 pole Accessory Lead, timer Instruction Book Fuse, 0.5A 250V MDL (115 input) Fuse, 0.25A 250V MDL (230V input) Switch, 2PDT slide, 115/230V 4/ Notes: 1/ See parts list for P/N 3710A for parts. 2/ Hardware available separately but does not have part numbers. Lid or enclosure not available separately. 3/ Not present in older models and should be added. 4/ Not present in older models and should be added if selectable input voltage is desired. 19

24 PARTS LIST Part No. 3710A Timer Assembly Description Schematic Drawing D Part No. Printed Circuit Boards Start/Stop Assembly Logic Assembly Mother Board Assembly Display Assembly Parts in PCBD 4121 Nand Gate Optical Coupler Voltage Comparator Parts in PCBD 4190 Oscillator Nand Gate Decade Counter Parts in PCBD 4191 Triac Transistor Relay, DIP Decade Counter Phase/Frequency Detector Multivibrator Parts in PCBD 4192 Driver Decoder Decade Counter Display, 3 digit, 7 segment Switch, pushbutton, 2PDT Switch, toggle, 2PDT Parts Mounted on Rear Panel Transformer B Regulator Parts Mounted on Front Panel Bezel Assembly (red lens) NOTES: 1. "Bare" printed circuit boards (without components) are not available. 2. Printed circuit boards contain two part numbers. Use only the assembly part numbers which should correspond to those given above. 20

25 Drawing No C, Figure 1 Model SST-2 With Autotransformer INSERT SCHEMATIC DRAWINGS 21

26 Drawing No C, Figure 2 Model SST-2 Without Autotransformer 22

27 Drawing No C, Figure 3 Model SST-2 With Input Selector Switch 23

28 Drawing No D Part No. 3710A Timer Assembly 24

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