PCB Technical documentation example (Part 2)
This example is intended to illustrate the technical documentation of an electronic design produced by AIRBORN ELECTRONICS. Most of the technical drawings in this page have been reduced in resolution so they can be viewed easily. The full sized diagrams may be downloaded from our circuit collection.
All material contained in this document is Copyright ©2010 AirBorn Electronics.



RCM710 ELECTRONIC SCALE

Technical Design Manual





RCM Weighing
SCALES & ENGINEERING SUPPLIES



    Contents:

    Document Part 1
  • Specification
  • Circuit diagrams: RCM710 Main CPU
  • Parts List
  • Parts Key and Packages
  • Specific Parts notes
  • Front Panel art

    Document Part 2

  • RCM710 Interboard connector (CN15 Lead)
  • Factory only adjustment #5
  • RCM710 Connector pinouts
  • 87C552 Pinout definition, as used in RCM710 project
  • Drilling diagram: RCM710 CPU
  • Overlay diagram: RCM710 CPU
  • Circuit diagram: RCM710 Keyboard/Display PCB
  • Parts List: Keyboard/Display PCB
  • Drilling diagram: RCM710 Keyboard/Display
  • Overlay diagram: RCM710 Keyboard/Display
  • Overlay diagram: RCM710 CPU, colour



RCM710 Interboard connector (CN15 Lead)

Description

The Lead is a 26 way 0.050 inch pitch ribbon cable, terminated at each end with 26 way IDC mini-female socket (bump or clip polarisation). Typical terminating connectors are type Fujitsu FCN747J026AU0.

RCM710 Interboard connector (CN15 Lead)



Factory only adjustment #5

Description

The factory only adjustment number 5 trims the +5v rail to 5.12v. This is needed for correct operation of the 87C552 A/D converter. The remainder of the circuitry on the PCB is also sensitive to power supply voltage, and having a stable reference voltage will ensure satisfactory operation.

Trimming of this voltage to a voltage other than 5.12v could have an adverse effect on the operation of the RCM710 unit. The adjustment should only be made in the factory, with proper calibrated equipment.

Equipment

  • Digital voltmeter, 4 digit, accuracy better than +/-0.1% or +/-4 LS digits of display
  • Connection lead, CN16 plug to voltmeter input terminals
  • Test transformer and Test jig to hold PCB in stable position
  • Small flat blade screwdriver
  • Serial number stickers
  • Record book

Procedure

  1. Apply a serial number sticker to the PCB
  2. Place the board for adjustment into the test jig
  3. Connect up CN1 and CN16
  4. Apply power to the test transformer
  5. Observe the voltmeter, if power is not 4.75 - 5.5v, remove power, repair PCB for power supply fault
  6. Observe the diag LEDs, if initial flash is not seen, remove power, repair PCB for processor run fault
  7. Do further testing as appropriate - e.g. monitor further diag LED flashes.
  8. Wait the 'warm up time'
  9. Adjust 10 turn pot VR1 until the voltmeter reads 5.118V to 5.123V
  10. Apply a small drop of superglue to hold the pot wiper in place
  11. Record the serial number and the voltage
  12. Mark the PCB as calibrated to adjustment #5
  13. After final test and inspection, cover the pot adjuster in epoxy to discourage tampering
  14. If a PCB should require readjustment during later repair, replace VR1.

Tests

Test how far the 5.120v supply drifts with:

  • Warm up
  • Temperature
  • Ageing (e.g. 1 month)

Provisional Transformer specification - Stage 4 Electronic Scale headwork

5 November 1993

Construction:

  • EI Style transformer to appropriate Australian Standard
  • either, PCB mount, with pins for connections
  • or, Chassis mount with insulated, coloured, stranded wires for connections

Winding:

  • Either, Split bobbin
  • or,Bifiliar wound with copper shield between primary and secondary ("Electrostatic shield")

Primary:

  • 240VAC.
  • If wires are provided for the primary connection they shall be coloured brown and blue, and no other wires on the transformer shall in that case be brown or blue.
  • The connections for the primary (either pins or wires) shall be segregated from the connections for the secondary by as much as possible.

Secondaries

  • Secondary 1: 7.5V AC 1 Amp rms
  • Secondary 2: 15V AC 0.22 Amp rms
  • Secondary 3: 1.6-0-1.6, i.e. 3.2 V AC 0.12 Amp rms with a centre tap
  • Secondary 4: 30V AC 0.05 Amp rms
  • Label: RCM710 Trfm
  • Protection: Varnish Impregnated or other suitable environmental protection



RCM710 Connector Pinouts

CN1 - Transformer

10 Way 0.2 inch pitch Weidmuller-Klippon SL10-H or wafer connector

  1. T7V 7.5VAC 1A Winding, connection 1
  2. T7V` 7.5VAC 1A Winding, connection 2
  3. T15V 15VAC 0.22A Winding, connection 1
  4. T15V` 15VAC 0.22A Winding, connection 2
  5. T1.6V 1.6-0-1.6VAC 0.1A Winding, connection 1
  6. T0V 1.6-0-1.6VAC 0.1A Winding, connection 3 (centre-tap)
  7. T1.6V` 1.6-0-1.6VAC 0.1A Winding, connection 2
  8. T30V 30VAC 0.05A Winding, connection 1
  9. T30V` 30VAC 0.05A Winding, connection 2
  10. Gnd Logic earth/Mains earth connection

CN2 - Primary Load Cell

8 Way 0.2 inch pitch Weidmuller-Klippon SL8-H

  1. Shield Inner foil shield around signal conductors
  2. +Excit +12.5v to load cell
  3. +Sens1 +12.5v to load cell (common with +Excit at the load cell connection)
  4. +Sig Load cell output signal (+)
  5. -Sig Load cell output signal (-)
  6. -Sens1 0v power to load cell (common with -Excit at the load cell connection)
  7. -Excit 0v power to load cell
  8. Chassis Connection to the chassis of the Load cell - outer braid of shield if double shielded cable is used. Not to be connected to pin 1 shield.

CN3 - Bus COM's

3 Way 0.2 inch pitch Weidmuller-Klippon SL3-H

  1. Shield Foil shield around signal conductors
  2. BUSA+ COM's positive
  3. BUSA- COM's negative

CN4 - Feature connector

8 Way 0.1 inch pitch posts

  1. P1.1
  2. P1.2
  3. P1.3 (This signal also shared with Iint)
  4. Key Post cut at this position, hole on connector blinded. (Pad Gnd on Layout)
  5. UsrC (This signal also shared with User control - Wiper of Pot)
  6. Gnd
  7. +5v
  8. +15v

CN5 - Batcher connector

8 Way 0.1 inch pitch posts

  1. Rly1 Fast Fill relay buffered output, +5v = operate relay
  2. Key Post cut at this position, hole on connector blinded.
  3. Rly2 Slow Fill relay buffered output, +5v = operate relay
  4. P4.2
  5. P4.3
  6. Gnd
  7. +5v
  8. +15v

CN6 - Printer module connector

6 Way 0.1 inch pitch posts

  1. P2.4 PDatOut
  2. P2.5 PClk
  3. P2.6 PLoad
  4. P2.7 PDatIn
  5. Gnd
  6. +5v

CN7 - Ancillary COM's module connector

8 Way 0.1 inch pitch posts

  1. RxDB
  2. TxDB
  3. Key Post cut at this position, hole on connector blinded.
  4. CTSB
  5. DTRB
  6. Gnd
  7. +5v
  8. Chassis earth

CN8 - System COM's RS232 module connector

8 Way 0.1 inch pitch posts

  1. RxDA
  2. TxDA
  3. Key Post cut at this position, hole on connector blinded.
  4. CTSA
  5. DTRA
  6. Gnd
  7. +5v
  8. Chassis earth

CN9 - I2C Connector A

5 Way 0.1 inch pitch posts

  1. SDA
  2. SCL
  3. IInt I2C Interrupt - usually unused
  4. +5v
  5. Gnd

CN10 - I2C Connector B

5 Way 0.1 inch pitch posts

  1. SDA
  2. SCL
  3. IInt I2C Interrupt - usually unused
  4. +5v
  5. Gnd

CN11 - Remote print switch

4 Way 0.2 inch pitch Weidmuller-Klippon SL4-H

  1. Gnd
  2. Prnt Print switch connection - return side of switch to Gnd
  3. UsrC User control connection (wiper) - return other pot terminals to Gnd, +5v.
  4. +5v

CN12 - Analog output connector

4 Way 0.1 inch posts

  1. Gnd
  2. ANOUT1 Raw analog output signal, approx 8v - 2v range
  3. +5v
  4. +15v

CN13 - Chassis connection

Spade connector

  1. Chassis (One pin only) Bonds to single point metal case/mains earth connection.

CN16 - Vtest

2 Way 0.1 inch posts

  1. Gnd
  2. +5.12v This connector is used during factory only adjustment #5

CN14 - Alternate Load Cell

10 Way 0.1 inch posts

  1. Gnd
  2. +Excit Wiring to Alternate Load Cell must be identical in length and type to main load cell.
  3. +Sens2
  4. Raw2 Output of Instrumentation Amp inputting -SIG2, +SIG2, using CENTRE, CALSIG.
  5. Centre Assumed centre of -SIG2, +SIG2, not quite 100% accurate in that it uses -Sens1.
  6. -Sens -Sens is a direct connection to -Sens1. -Sens2 as a separate signal does not exist.
  7. -Excit
  8. Chassis
  9. +15v
  10. Calsig Calsig is a direct connection to the identical calibration signal for the Main load cell.

CN15 - Interboard connector (Display-Keyboard)

26 Way 0.1 inch x 0.1 inch dual row Insulation Displacement Connector (Suitable example part number: PCB - Fujitsu FCN744P034AUR, Cable - FCN747B034AUO)

  1. +VF High voltage power supply for the Vacuum fluro display.
  2. VFILA Filament supply voltage for the Vacuum fluro display.
  3. VFILB Filament supply voltage.
  4. Gnd Ground
  5. P0.0 Fluro segment 0, Keyboard return 0. See 87C552 pinout for signal details.
  6. P0.1 Fluro segment 1, Keyboard return 1.
  7. P0.2 Fluro segment 2, Keyboard return 2.
  8. P0.3 Fluro segment 3, Keyboard return 3.
  9. P0.4 Fluro segment 4, Keyboard return 4.
  10. P0.5 Fluro segment 5, Keyboard return 5.
  11. P0.6 Fluro segment 6, Keyboard return 6.
  12. P0.7 Fluro segment 7, Keyboard return 7.
  13. P3.6 Fluro segment 8.
  14. P3.7 Fluro segment 9.
  15. P2.0 Scan 0. Scan0-3 (together) select a fluro grid and a keybd scan to turn on.
  16. P2.1 Scan 1.
  17. P2.2 Scan 2.
  18. P2.3 Scan 3.
  19. *PWM0 Piezo. 0 = Voltage across Piezo element.
  20. *PWM1 Brightness. 0 = Fluro element on, Keybd off. 1 = Fluro off, keybd on.
  21. Prnt Print switch.
  22. P5.1 NTC Thermistor.
  23. P5.2 Light dependent resistor.
  24. P5.3 Program mode - Revision level link.
  25. IRRX Infra-red receive.
  26. +5v +5v supply.

J1 - Load Cell Sensitivity

3 Way 0.1 inch posts - short with 2 Way shunt

  • 1-2 Link for 3mV/V Load cell sensitivity
  • 2-3 Link for 2mV/V Load cell sensitivity

J2 - Programming Link

3 Way 0.1 inch posts - short with 2 Way shunt Also used as special connector for "Dongle" operation

  • 1-2 Link for normal operation
  • 2-3 Link to place unit in programming mode

J2 - Dongle connector

3 Way 0.1 inch posts Also used as Programming link when no Dongle present

  1. +5v
  2. PrgL Program - Revision link line
  3. Gnd

J3 - RS485 Termination Link

3 Way0.1 inch posts - short with 2 Way shunt

  • 1-2 Link to Terminate RS485 line in unit
  • 2-3 Link if the RS485 line is terminated elsewhere (e.g. in another unit)



87C552 Pinout definition

RCM710 Headworks

Pin	Name		Function
1	P5.0	In	Analog input.  Print Switch
2	Vdd		+5v
3	STADC		Gnd
4	*PWM0 Out	Piezo.  0 = Voltage across Piezo element
5	*PWM1 Out	Brightness.  0 = Fluro on, keyboard off  1 = fluro off, keyboard on
6	*EW		Gnd
7	P4.0	Out	Integrator select A:  0 = -Sig or DoRef  1 = Vdd/2
 "	  "		Upgood strobe.  Strobes continuously during correct code operation.
8	P4.1	Out	Integrator select B:  0 = DoRef  1 = -Sig or DoRef
9	P4.2	Out	Fast fill relay.  0 = Operate relay
10	P4.3	Out	Slow fill relay.  0 = Operate relay
11	P4.4	Out	Diag LED 1:  Green
 "	  "		Force10v.  1 = Force excitation voltage to 10v instead of 12.5v
12	P4.5	Out	Diag LED 2:  Red
 "	  "		ATest.  0 = Add analog test voltage into input circuitry
13	P4.6	Out	RTSA.  Direction control for RS485 port in system mode.  0 = Transmit
 "	  "		DTRA.  Handshake line for channel A (System) 0 = +12v output = active
14	P4.7	Out	DTRB.  Handshake line for channel B (Ancillary) 0 = +12v output = active
15	RST	In	Reset.  Capacitor to +5v.  When input is at +5v, processor is reset.
16	P1.0	In	Settle.  0 = Discharging integrator capacitor.  1 = Integrating.
17	P1.1	In	I2C interrupt input (Potentially unused)  0 = Interrupt
 "	  "	In/Out	Feature connector pin 1
18	P1.2	In/Out	Feature connector pin 2
19	P1.3	In/Out	Feature connector pin 3
20	P1.4	In	CTSA.  Handshake line for channel A (System).  0 = +12v = active: ok to send data on TxDA
21	P1.5	In	CTSB.  Handshake line for channel  B (Ancill).  0 = +12v = active: ok to send data on TxDB
22	P1.6	In/Out	SCL.  I2C clock line.
23	P1.7	In/Out	SDA.  I2C data line.
24	P3.0	In	RxDA.  Serial Receive line for channel A (System).  0 = +12v = space, active data condition.
25	P3.1	Out	TxDA.  Serial Transmit line for channel A (System).  0 = +12v = space, active data condition.
26	P3.2	In	RxDB.  Serial Receive line for channel B (Ancill).  0 = +12v = space, active data condition.
27	P3.3	In	IRRx.  Demodulated carrier.  0 = active 38khz carrier present.
28	P3.4	Out	TxDB.  Serial Transmit line for channel B (Ancill).  0 = +12v = space, active data condition.
29	P3.5	Out	GagSel.  Gauge select signal.  1 = Standard gauge  0 = Alternative (#2) gauge
30	P3.6	Out	Fluro Segment 8.  1 = active, when a grid is active.  Note all segments go to '1' briefly at reset.
31	P3.7	Out	Fluro Segment 9.
32	nc		no connection
33	nc		no connection
34	XTAL2		Crystal connection
35	XTAL1		Crystal connection
36	Vss		Gnd
37	Vss		Gnd
38	nc		no connection
39	P2.0	Out	Scan0.  Scan0-Scan3 together select a fluro display grid to turn on, and/or a keybd line to scan.
40	P2.1	Out	Scan1.
41	P2.2	Out	Scan2.
42	P2.3	Out	Scan3.
43	P2.4	Out	Printer module connector pin 1.	PDatOut
44	P2.5	Out	Printer module connector pin 2.	PClk.	Positive transition = latch valid data on PDatOut
45	P2.6	Out	Printer module connector pin 3.	PLoad.	0 = active  1 = inactive.
 "	  "	Out					Strobe.	0 = active, as long as PDatOut is also 0.
46	P2.7	In	Printer module connector pin 4.	PDatIn.	Changed on Positive transition of PClk.
47	*PSEN	Out	Unused.  Should be permanently high.
48	ALE/ *PROG	Unused.  Should be an active high pulse at 1/6th of the crystal frequency.
49	*EA/Vpp	+5v
50	P0.7	Out	Fluro Segment 7.  1 = active, when a grid is active.  Note all segments go to '1' briefly at reset.
 "	  "	In	Keyboard return 7.  0 = active, when an appropriate keyboard scan line is selected.
51	P0.6	Out	Fluro Segment 6.  1 = active.
 "	  "	In	Keyboard return 6.  0 = active.
52	P0.5	Out	Fluro Segment 5.  1 = active.
 "	  "	In	Keyboard return 5.  0 = active.
53	P0.4	Out	Fluro Segment 4.  1 = active.
 "	  "	In	Keyboard return 4.  0 = active.
54	P0.3	Out	Fluro Segment 3.  1 = active.
 "	  "	In	Keyboard return 3.  0 = active.
55	P0.2	Out	Fluro Segment 2.  1 = active.
 "	  "	In	Keyboard return 2.  0 = active.
56	P0.1	Out	Fluro Segment 1.  1 = active.
 "	  "	In	Keyboard return 1.  0 = active.
57	P0.0	Out	Fluro Segment 0.  1 = active.
 "	  "	In	Keyboard return 0.  0 = active.
58	AVref-		Gnd
59	AVref+	+5v.  For purposes of this pin the +5v supply is actually trimmed to 5.120v.
60	AVss		Gnd
61	AVdd		+5v
62	P5.7	In	Analog input.  IOut.  Test diagnostic line to monitor integrator output voltage, divided by 4.
63	P5.6	In	Analog input. RawAnout.  Test diagnostic line to monitor raw analog signal, divided by 4.
64	P5.5	In	Analog input. +Excite.  Test diagnostic line to monitor Bridge excitation voltage, divided by 4.
65	P5.4	In	Analog input.  Potentiometer input.
66	P5.3	In	Analog input.  Program mode - Revision level link on Keyboard-display PCB.
67	P5.2	In	Analog input.  Light dependent resistor.
68	P5.1	In	Analog input.  NTC thermistor, for temperature measurement.



Drilling Diagram: RCM710 CPU Board

[Full resolution diagrams can be viewed in the circuit collection]


Overlay Diagram: RCM710 CPU Board




Circuit Diagram: Keyboard/Display PCB 


RCM2_1.PCB  1:51  25-8-1996       PCB Parts List

A1                                                     LOGO1
CN15               RCM710 HEADWORKS PCB                IDC26
D1                 BAW62                               DIODE0.3
D2                 BAW62                               DIODE0.3
D3                 BAW62                               DIODE0.3
DISP1              FIP6A13A                            FIP6A13A
IC1                4051                                DIP16
IC2                4051                                DIP16
IC3                SA594                               DIP18
IC4                SA594                               DIP18
IC5                74HCT04                             DIP14
PZ1                PIEZO                               RB.4/.8
R1                 27K                                 AXIAL0.4
R2                 10K                                 AXIAL0.4
R3                 10K                                 AXIAL0.4
S1                 KEY:1                               KEY-SW
S2                 KEY:2                               KEY-SW
S3                 KEY:3                               KEY-SW
S4                 KEY:4                               KEY-SW
S5                 KEY:5                               KEY-SW
S6                 KEY:6                               KEY-SW
S7                 KEY:7                               KEY-SW
S8                 KEY:8                               KEY-SW
S9                 KEY:9                               KEY-SW
S10                KEY:0                               KEY-SW
S11                KEY:TARE                            KEY-SW
S12                KEY:FIX                             KEY-SW
S13                KEY:CLR                             KEY-SW
S14                KEY:SUB                             KEY-SW
S15                KEY:PRINT                           KEY-SW
S16                KEY:FEED                            KEY-SW
S17                KEY:ZERO                            KEY-SW
Total Components = 32



Drilling Diagram: RCM710 Keyboard/Display Board

[Apologies: Poor resolution is the result of scaling to fit page format]
[Full resolution diagrams can be viewed in the circuit collection]


Overlay Diagram: RCM710 CPU Keyboard/Display Board




Overlay Diagram: RCM710 CPU Board: Colour

This diagram is not normally included in the technical documentation package, because of difficulties in reproduction.




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