Guildline 6560 Technical Manual

Resistance calibrator

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TECHNICAL MANUAL

FOR

MODEL 6560

"RESISTANCE CALIBRATOR"

NOTICE

The contents and information contained in this manual are

proprietary to Guildline Instruments. They are to be used only as a

guide to the operation and maintenance of the equipment with

which this manual was issued and may not be duplicated or

transmitted by any means, either in whole or in part, without the

written consent of Guildline Instruments.

TM6560-J-00

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Summary of Contents for Guildline 6560

Page 1 NOTICE The contents and information contained in this manual are proprietary to Guildline Instruments. They are to be used only as a guide to the operation and maintenance of the equipment with which this manual was issued and may not be duplicated or transmitted by any means, either in whole or in part, without the written consent of Guildline Instruments.
Page 2: Table Of Contents
TABLE OF CONTENTS 1INTRODUCTION 1 SCOPE ............................1 GENERAL DESCRIPTION ......................1 SPECIFICATIONS ............................. 2 OPERATING INSTRUCTIONS........................5 INSTALLATION ........................... 5 FRONT PANEL INDICATORS ..................... 5 3.2.1 DISPLAY WINDOW ..................5 3.2.2 GUARD INDICATOR..................7 3.2.3 CAL MODE INDICATOR................7 3.2.4 2-TERMINAL INDICATOR ................
Page 3 RESISTOR? - DISPLAY THE CURRENTLY SELECTED RESISTOR ....36 4.2.21 ROMCHECKSUM? - DISPLAY THE ROM CHECKSUM....... 36 4.2.22 SINCE? - DISPLAY THE TIME THE 6560 WAS LAST RESET ......37 4.2.23 SERIALNUMBER - SET THE 6560 SERIAL NUMBER ........37 4.2.24 SOFCAL - SET CALIBRATION COEFFICIENTS .........
Page 4 5.1.1 OPTION SWITCHES 1 TO 4 - RESERVED............41 5.1.2 OPTION SWITCH 5 - 50/60 Hz SELECT ............42 5.1.3 OPTION SWITCH 6 - LAST RESISTANCE............42 5.1.4 OPTION SWITCH 7 - OPEN/SHORT............. 42 5.1.5 OPTION SWITCH 8 - FACTORY CALIBRATION.......... 42 SPECIFICATION VERIFICATION......................
Page 5 DRAWINGS ............................. 72...
Page 6 LIST OF FIGURES Figure 3.1: Keyboard and Display ....................6 Figure 3.2: Rear Panel........................11 Figure 3.3: Opening the Power Receptacle ................12 Figure 3.4: Switch Settings......................14 Figure 3.5: Ideal Circuit........................ 15 Figure 3.6: Functional Circuit...................... 16 Figure 3.7: Leakage Circuit......................
Page 7 LIST OF TABLES Table 2.1: Basic Instrument Specifications ..................... 2 Table 2.2: Resistance Specifications (4-wire Mode) ..................4 Table 3.1: Recommended Fuses ........................12 Table 3.2: Line Cord Wiring..........................13 Table 3.3: GPIB Mode Switches........................14 Table 4.1: IEEE-488.1 Pin Designations......................21 Table 4.2: GPIB Device Capabilities.......................
Page 8: Scope
Guildline Instrument's 6560 Resistance Calibrator. GENERAL DESCRIPTION The 6560 Resistance Calibrator provides a wide range of high precision resistors selected for use in calibrating ohm-meters. All of the resistors may be selected under remote control from the GPIB interface, this is especially useful in automated calibration setups.
Page 9: Specifications
SPECIFICATIONS ┌──────────────────────────────────────────────────────┐ Specifications for Guildline Instruments │ │ 6560 Resistance Calibrator │ │ ╞══════════════╤══════════════════════════╤════════════╡ 23 ± 5 │Operating │ │°C │ │ ├──────────────────────────┼────────────┤ 70 ± 8 │Temperature │ │°F │ ├──────────────┼──────────────────────────┼────────────┤ │Operating │ │ │ < 70% │Humidity │ │R.H.
Page 10 Other features include: • Bench top mounting or rack mount with extra flanges provided separately. • Hidden voltage selection switch on rear panel. • GPIB Bus Address selectable from rear panel. Each resistance element will be within 0.1% of the nominal value. The actual resistance values will be displayed on the instrument's front panel readout with an uncertainty which is the sum of the following: the uncertainty of the original calibration.
Page 11: Table 2.2: Resistance Specifications (4-Wire Mode)
Resistance Specifications (4-wire mode) for Guildline Instruments 6560 Resistance Calibrator Nominal Stability (23°C ±2 K) TC/K Maximum Value (±ppm) Current (Ω) (mA) 24 Hrs 90 Days 1 Yr (±ppm) (±ppm) (±ppm) Short 0 500 6 400 6 300 10.0 2.5 100 19.0...
Page 12: Operating Instructions
FRONT PANEL INDICATORS There are numerous visual indicators on the front panel of the 6560. These indicators display the value and status of the currently selected resistance, the status of the guard circuits, and the status of the remote interface.
Page 13: Figure 3.1: Keyboard And Display
Figure 3.1: Keyboard and Display...
Page 14: Guard Indicator
3.2.8 TALK INDICATOR A red LED indicates that the 6560 is sending data to the remote control interface (GPIB). When the 6560 is controlled from the GPIB interface the TALK indicator is lit when the interface is addressed as the talker (talker active state) and extinguished when the remote controller unaddresses the 6560.
Page 15: Local Indicator
Some of the membrane push buttons have integral LED indicators. 3.3.1 POWER SWITCH Connects AC power to the 6560 when depressed. 3.3.2 REMOTE LOCAL KEY This key will return local control when pressed and extinguish the remote red Led indicator unless the remote controller has disabled the entire keyboard.
Page 16: Cal Mode Key
3.3.6 CAL MODE KEY When this key is pressed the instrument will alternately enter or exit CAL MODE. It is not possible to enter CAL MODE unless the key switch on the rear panel is set to the CAL position. When the instrument is in CAL MODE all controls and indicators operate normally and the CAL EDIT key is made operative.
Page 17: Enter Key
3.4.1 VOLTAGE SELECTION DRUM This drum allows the 6560 operator to select the input voltage of the instrument from one of 100, 120, 220, or 240 volts. It is important that the correct input voltage be selected before any attempt is made to operate the instrument. To change the selected input voltage, after removing the line cord from the receptacle, pry open the power receptacle as shown in Figure 3.3.
Page 19: Figure 3.3: Opening The Power Receptacle
Figure 3.3: Opening the Power Receptacle Check to see that the fuses inserted in the receptacle correspond to the type specified in Table 3.1. Only fuses of the specified type should be used. ┌──────────┬────────────────┐ │ LINE │ FUSE TYPE │ │...
Page 20: Gpib Address Switches
The GPIB mode (disabled, talk-only, or talk/listen) is set by switches 6 and 7, the possible settings for the switches are shown in Table 3.3. The 6560 does not support the talk-only, or listen-only modes, the modes are available only for consistency with other instruments manufactured by Guildline.
Page 21: Figure 3.4: Switch Settings
Figure 3.4: Switch Settings GPIB mode Interface Disabled Talk-only Interface Disabled Talk/Listen Table 3.3: GPIB Mode Switches...
Page 22: Normal/Cal Key Switch
3.4.3 NORMAL/CAL KEY SWITCH The NORMAL/CAL switch is activated with a key, the key may be removed (for security) when it is in the vertical (NORMAL) position. When the key is in the NORMAL position it is not possible to change the calibration coefficients from the bus or from the front panel. When the key is in the horizontal (CAL) position it is possible to change the calibration coefficients.
Page 23: Figure 3.6: Functional Circuit
The reference current is applied across the C and C terminals, if there is a series resistance in the leads (represented by R and R in Figure 3.6) the current flowing through the resistance element (R in Figure 3.6) will not be affected, hence the contribution of R and R to the measurement can be ignored.
Page 24: Current Terminal 1
Figure 3.7: Leakage Circuit The magnitudes of the lead resistances (R , and R ) shown in Figure 3.6 are about 100 mΩ. The leakage resistances (R and R ) shown in Figure 3.7 are about 10 TΩ. The guard resistance (R Figure 3.7) will be approximately equal to the resistance element.
Page 25: P - Potential Terminal 1
GUARD circuit. The processor ground is at the same potential as GPIB ground. REAR PANEL CONNECTORS There are two connectors on the rear panel of the 6560. These connectors are for AC line power and for computer communications (GPIB). 3.6.1 GPIB DATA CONNECTOR The signals at the GPIB data connector are described in detail in Section 4.1.
Page 26 Press the CAL EDIT key, the displayed value should start to flash. Using the 0-9 digit keys, the decimal point key (.), the BACK SPACE key and the ↓kΩ and ↑MΩ keys enter the desired value. The new value should be flashing at all times. Press the ENTER key.
Page 27: Remote Control
SR1 - the 6560 has complete service request generation capabilities. RL1 - all functions except Power on the front panel of the 6560 can be locked out by the GPIB controller. The 6560 does not have an indicator on the front panel to indicate when it is in the local lock out state.
Page 28: Table 4.1: Ieee-488.1 Pin Designations
╒════╤════════╤══════════════════════════════════════════════════╕ │PIN │ NAME │ DESCRIPTION │ ╞════╪════════╪══════════════════════════════════════════════════╡ │ 1 │ DIO1 │ Data Input Output Line 1 │ ├────┼────────┼──────────────────────────────────────────────────┤ │ 2 │ DIO2 │ Data Input Output Line 2 │ ├────┼────────┼──────────────────────────────────────────────────┤ │ 3 │ DIO3 │ Data Input Output Line 3 │...
Page 29: Table 4.2: Gpib Device Capabilities
The GPIB input buffer is 256 bytes long, the input full bit is set when the buffer is above 75% full (64 bytes remaining), hence if the programmer limits messages sent to the 6560 to 32 bytes and checks the IFL bit in the status register before sending each message then under normal operating conditions the buffer should never overflow.
Page 30: Gpib Output Buffering
4.1.3 GPIB DEADLOCK If the GPIB bus controller demands a byte of data from the 6560 and the output buffer is empty and this condition persists for a period of 8 seconds, the 6560 will place the current resistance (see Resistor? command) into the output buffer and use this value to satisfy the controllers demand for data.
Page 31 6560 as a listener, the 6560 enters the remote state. The REMOTE LED on the front panel of the 6560 will be lit when the 6560 is in the remote state. Front panel operation is restricted to the use of the POWER switch and the REMOTE LOCAL key.
Page 32: Unrecognized Gpib Commands
The command parser in the 6560 will accept most command short forms, and misspellings (see cautionary note in Section 4.2.20). 4.1.9 GPIB END OF MESSAGE TERMINATOR The 6560 will place a Line Feed (0X0A) at the end of each reply. The EOI flag will not be set.
Page 33: Gpib Commands
GPIB COMMANDS 4.2.1 *ESE - SET EVENTS ENABLE REGISTER This command sets the standard event status enable register bits. When the bits in the Event Status Enable (ESE) register are "ANDed" with the bits in the Event Status Register (ESR) if the result is non-zero then the Event Status Bit (ESB) in the Status Byte Register (STB) is set (see Figure 4.1).
Page 34: Figure 4.1: Event Status Bit Operation
│ │ │ │ ├────┼──────┼───────┼────────────────────────────────────────────┤ │ 1 │ │ RQC │ ReQuest Control. This event bit indicates │ │ to the GPIB controller that the 6560 is │ │ │ │ │ requesting permission to become the con- │ │ │...
Page 35: Idn? - Identification Query
4.2.5 *OPC - OPERATION COMPLETE This command will cause the 6560 to set the Operation Complete bit (bit 0) in the Event Status Register. Since the 6560 processes all commands sequentially the operation complete bit will be set as soon as the command is parsed.
Page 36: Rst - Device Reset
Guildline Instruments does not supply a numeric data processor. The standard Intel Math Coprocessor for IBM PC and Compatibles with 5 MHz 8086 or 8088 will operate in the 6560. The Intel order number is PCPN8087.
Page 37: Sre? - Service Request Enable Query
This command performs the same action as a group execute trigger on the GPIB interface. Since the 6560 processes all commands when they are received (execution is not delayed) this command will set the execution error bit in the event status register (bit 4).
Page 38: Table 4.5: Status Byte Register
┌────────────┬──────────┬────────────────────────────────────────────┐ │ LOCATION │ NAME │ DESCRIPTION │ ╞═════╤══════╪══════════╪════════════════════════════════════════════╡ │ 0 │ LSB │ TIME │ System Time has Changed. This bit is set │ │ once each second as the real time clock │ │ │ │ │ ticks, and is cleared by the execution of │ │...
Page 39: Date - Set The System Date
0, 1, 2, 3, 4, 5, 6, 7, 8, 9, B, C, D, E, F, M, R, S, T, U, X, ? where ? indicates that no keys have been pressed since the 6560 was last Reset. The verbose reply will be preceeded with "KEY". The meanings of the various key characters are...
Page 40: Key Enter A Keystroke
Table 4.6: Keyboard Character Designations 4.2.17 KEY <KEYNAME> ENTER A KEYSTROKE The Key command causes the 6560 to perform actions similar to the actions performed when a front panel key is pressed. Allowable values for <keyname> are: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, B, C, D, E, F, M, R, S, T, U, X, ? where each of these is a single ASCII character.
Page 41: Options? - Display The Option Switch Settings
1) the round-off errors, and 2) the actual values of the 1.0 Ω and the 1.9 Ω resistors. The 6560 will not change between 2-wire mode and 4-wire mode when attempting to select the closest available resistor. After the relays have been changed (about 200 ms) the OPC (Operation Complete) Bit in the Event Status Register (see Section 4.2.3) register...
Page 42: Resistor? - Display The Currently Selected Resistor
CHK bit in the Status Byte Register to be set to one (1). It should be noted that the CHK bit will only be set once after the 6560 is powered on, hence simply waiting for the CHK bit to become set may not always work if the RomChecksum had been previously read.
Page 43: Since? - Display The Time The 6560 Was Last Reset
4.2.22 SINCE? - DISPLAY THE TIME THE 6560 WAS LAST RESET This query command will display the time the 6560 was last powered up (or reset). The verbose reply will be: SINCE Thu Jun 2, 10:55:22 1988 or the terse mode: Thu Jun 2, 10:55:22 1988 where the date displayed will depend upon the startup date.
Page 44: Sofcal? - Examine Calibration Coefficients
A valid SOFCAL command is: SOFCAL 19.00176 where the value 19.00176 is dependant upon the desired calibration value. If the numeric parameter is missing from the command, or does not meet the conditions enumerated above, then the EXE (Execution Error) bit in the Event Status Register will be set and no calibration coefficients will be modified.
Page 45: Terse - Turn Off Verbose Mode
January 1st 1970 Greenwich Mean Time (GMT). When a time is input or displayed it is converted either to or from local time. In order for the 6560 to be able to perform this conversion the instrument must know the current timezone.
Page 46: Verbose - Set Verbose Mode
PROGRAMMING HINTS In general a simple way to get the 6560 to select a resistance, or to program a calibration coefficient is to use the KEY command (see Section 4.2.17) and send the same keystrokes that would be used from the front panel.
Page 47: Options
OPTIONS DIP SWITCHES The 6560 has an 8 position piano style switch located as shown in Figure 5.1 on the Control pcb. Each of the 8 switches enable or disable an option. Figure 5.1: Location of Option Switch on Control PCB 5.1.1...
Page 48: Option Switch 5 - 50/60 Hz Select
If the option switch is in the open position then after power up the 6560 will select an open circuit. If the option switch is in the closed position then after power up the 6560 will select a short circuit. This switch will have no effect if option switch 6 is in the open position.
Page 49: Table 5.1: Option Switches
│ Switch │ Position ┌────────┬──────────┬────────────────────────────────────┐ │ Description │ ├────────┼──────────┼────────────────────────────────────┤ │1,2,3,4 │ Closed │ These switch positions are │ │ reserved by Guildline Instru- │ │ │ │ ments for future expansion. │ │ │ │ They should be left in the │...
Page 51: Specification Verification
SPECIFICATION VERIFICATION ULTIMATE SPECIFICATIONS The ultimate specifications for the 6560 Resistance Calibrator can be verified by measuring the value of each resistance element with respect to a primary standard. This section below outlines the recommended procedure for measuring and verifying the accuracy of the resistance elements in the 6560 Resistance Calibrator.
Page 52: Resistance Measurement With A 9975 Current Comparator
RESISTANCE MEASUREMENT WITH A 9975 CURRENT COMPARATOR The front panel of the 9975 is shown in Figure 6.1. Figure 6.1: 9975 Current Comparator 6.2.1 10 kW AND BELOW The following section describes the steps which must be followed in order to measure resistance less than or equal to 10 kΩ.
Page 53: Figure 6.2: 9975 Current Comparator Connections For Measurement Of
Set the 9975 Current Comparator power switch to the OFF position. Using Guildline low thermal wire, connect the four 6560 Resistance Calibrator terminal leads to the 4 terminals labeled R , on the side panel of the 9975 Current...
Page 54 Set the MAN AUTO switch on the on the side panel of the 9975 to the current reversal mode desired. The automatic mode is satisfactory for all measurements of resistances in the 6560. Set the REV RATE SEC switch to the desired frequency. Normally a setting of 4 seconds is used for low values of R (1 Ω...
Page 55 Turn the GALVANOMETER D1/D2 switch to D1 and set the unknown resistor current ) to the desired value by means of the CURRENT I mA switch (e.g. 1 mA). In general the I current should be made as large as possible to minimize circuit noise effects, but within the constraint that it must not produce excessive self heating in the unknown resistor.
Page 56 19 kΩ to 100 kΩ. The set up for these measurements is shown in Figure 6.3. Set the 9975 Current Comparator power switch to the OFF position. Connect the three 6560 Resistance Calibrator terminal leads (P and C...
Page 57: 19 Kω And 100 Kω
Figure 6.3: 9975 Current Comparator connections for measurement of resistances between 19 kΩ and 100 kΩ...
Page 58 Set the MAN-AUTO switch on the side panel of the 9975 to the current reversal mode desired. The automatic mode is satisfactory for all measurements of resistances in the 6560. Set the REV RATE SEC switch to the desired frequency. Normally a setting of 4 seconds is used for low values of R (1 Ω-10 kΩ).
Page 59: Table 6.1: Current I
Turn the GALVANOMETER D1/D2 switch to D1 and set the unknown resistor current ) to the desired value by means of the CURRENT I mA switch (e.g. 1 mA). In general the I current should be made as large as possible to minimize circuit noise effects, but within the constraint that it must not produce excessive self heating in the unknown resistor.
Page 60: Above 100 Kω
rebalance the R dials on the 9975 so that the balanced condition will correspond to the zero trace. 6.2.3 ABOVE 100 kW The following section describes the steps which must be followed in order to measure resistances greater than 100 kΩ. The setup for these measurements is shown in Figure 6.4. NOTE: The output of the 9607 High Voltage Reversing Switch generates very large transient impulses upon reversals.
Page 61: Figure 6.4.: 9975 Current Comparator Connections For Measurement Of Resistances Greater Than 100 Kω
Figure 6.4.: 9975 Current Comparator connections for measurement of resistances greater than 100 kΩ.
Page 62 Connect the P and C terminals of the 6560 Resistance Calibrator to the R terminals on the side panel of the 9975, again these connections should be made with shielded cable, and the shield should be connected to ground.
Page 63 CAUTION If the OSC indicator should go out while the 9975 is turned on, the power to the 9975 should be immediately turned off. Set the galvanometer to approximately zero by adjusting the zero control on the side of the photocell amplifier itself. Set the OUT PCA switch back to the PCA position.
Page 64: Basic Specifications
A TIME CONSTANT setting of 3S will filter most of this out. BASIC SPECIFICATIONS The basic specifications for the 6560 Resistance Calibrator can be verified by measuring the value of each resistance element with respect to a recently (24 hrs) calibrated long scale DMM (Datron 1281).
Page 65: Principles Of Operation
+5.0 V DC at 3.0 amperes, and ±12 V DC at 1.0 amperes, with a total capacity of 40 watts. This is more than enough power to satisfy the requirements of the 6560. The primary side of the transformer can be wired to accept one of the following voltages: 100 V AC, 120 V AC, 220 V AC, or 240 V AC.
Page 66: Power And Control
7.3.1 POWER AND CONTROL The power and control section of the Control pcb (100 series components) monitors the AC line and synchronizes the output to the control Triacs with the AC line zero-crossings. BROWN-OUT DETECTOR - When the AC line voltage drops, the voltage of the junction of R102, R103 (which is proportional to AC line voltage) will drop below the voltage at the junction of RN101 and R104 (a fixed reference voltage) and the output (pin 7) of U101 will go high indicating a brown-out condition.
Page 67 8087 but the presence of an 8087 will improve response to many of the bus commands. Guildline Instruments does not supply a numeric data processor. The standard Intel Math Co-processor for IBM PC and compatibles with 5 MHz 8086 and 8088 will operate in the 6560.
Page 68: Memory
ROM, or a number of intermediate compromises. In addition the memory includes an 8-section piano switch which can be used to select various options. The 6560 is configured with 62 kbytes of ROM, 32 kbytes of RAM and 8 kbytes of non-volatile memory.
Page 69: Keyboard Interfaces
RS-232C BUFFERS (OPTIONAL) I.C.s U402 and U403 are standard RS-232C buffers which convert TTL signal levels to RS-232C signal levels and RS-232C signal levels to TTL signal levels. D401 and D402 protect the control pcb in event of a failure such as connecting 120 V AC to the transmit data pin.
Page 70: Gpib Interface
7.3.7 GPIB INTERFACE The GPIB interface is built up from a Motorola 68488 controller IC (U701) and two buffers (U702 and U703). The GPIB address is gated onto the processor data bus by U704. U102 inverts the polarity of the interrupt output for the system interrupt controller. FRONT PANEL pcb This assembly is complete with display, keyboard, and interface to the Resistor/Relay pcb.
Page 71: Light Emitting Diodes
7.4.3 LIGHT EMITTING DIODES The status of a particular Light Emitting Diode (LED) is selected by the processor by latching data into the dual four-bit latches U5, U6 and U7. The latches latch the data which the processor has presented on the data lines (C0-3) when the processor presents the correct address on the address lines (A0-4).
Page 72: Software
SOFTWARE The control program within the 6560 is the "glue" which joins the interfaces and the microprocessor together. The major interfaces to the processor are the keyboard and display (ultimately the user), and the remote computer interface (IEEE-488). The 6560 control program is approximately 42-thousand bytes long. It is written in the "C"...
Page 73: Troubleshooting And Maintenance
8.2.1 SETTING THE INTERNAL REAL TIME CLOCK The 6560 Resistance Calibrator maintains an internal real time clock so that the date and time of the last calibration can be maintained automatically. The real-time clock can be set from the GPIB bus interface or the front panel. In order to set the real-time clock first...
Page 74: Checking The Rom Checksum
8.2.2 CHECKING THE ROM CHECKSUM The software in the 6560 Resistance Calibrator is stored in a Read Only Memory (ROM) device. The integrity of the data stored in the ROM is essential to the correct operation of the instrument. It is possible to test the ROM data by first entering diagnostics mode (see Section 8.2), then pressing the '1' key, the instrument will spend about 20 seconds...
Page 75: Testing The Relay Drivers
8.2.4 TESTING THE RELAY DRIVERS It is possible to test the relay driver logic on the resistor pcb from the front panel diagnostics mode. This can be done by entering diagnostics mode (see Section 8.2) then pressing either the '3' key or the '4' key. When the '3' key is pressed each of the relay drivers will be enabled sequentially.
Page 76: Testing The Gpib Switches
The severity of the environment to which the 6560 is subjected determines the frequency of maintenance. A convenient time to perform preventative maintenance is preceding...
Page 77 The 6560 should be cleaned as often as operating conditions require. Accumulation of dirt in the instrument can cause overheating and component breakdown. Dirt on components acts as an insulating blanket and prevents efficient heat dissipation. It also provides an electrical conduction path which may result in instrument failure.
Page 78 PARTS LISTS (can be ordered from Guildline) Model 6560 PL18688.01.02 General Assembly PL18722.01.02 Display pcb PL18725.01.02 Resistor pcb PL18726.01.02 6560 CPU pcb...
Page 79 (can be ordered from Guildline) DRAWINGS 18688.01.02 General Assembly 18722.01.02 Display pcb Assembly 18725.01.02 Resistor pcb Assembly 18726.01.02 CPU pcb Assembly 18688.01.04 Main Assembly Schematic 18722.01.04 Display pcb Schematic 18725.01.04 Resistor pcb Schematic 18726.01.04 CPU pcb Schematic...