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Motorola MSF5000 SSCB Signals
Compiled by Robert W. Meister WA1MIK

(Originally created 13-Sep-06.
Revised and added all connectors 23-May-12.
Added all other signals 18-Jan-21.)
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This is a compilation of the signals on the SSCB schematic. The entire SSCB section from a UHF station service manual has been scanned and can be found here as a 1.3MB PDF file. The page numbers shown in the tables below reference the schematic diagram page (1-9 of 9 pages), NOT the PDF file page. Most of the pages were fold-out and were scanned as two separate halves, but everything is present.

Notes for all tables:

  1. An asterisk (*) after a signal name indicates active low (to ground).
  2. Src = page number where signal originates or enters via a connector.
  3. Dst = page number(s) that signal goes to leaves via a connector.

SSCB Schematic Signals:

This table shows all of the signals that travel between schematic pages or enter or leave the SSCB.

Abbreviations used in the "Notes" column:

  1. DISPLAY = signal used for front panel display.
  2. EEPOTS = signal used for all Electronically Erasable Potentiometers.
  3. EEPOT n = signal used for one specific EEPOT.
  4. LED = LED on front of SSCB.
  5. POST = used primarily for Power On Self Tests.
  6. SWITCH = front-panel toggle switch.

Signal NameSrcDstNotes
+5V 2 LOTS  
+9.6V 2 LOTS J801
ACCESS DISABLE* 3 4 SWITCH
AGC REF 8 8 800/896 MHZ ONLY
ALERT TONE 0..3 4 1  
ALERT TONE AUDIO 1 6,8  
ALERT TONE LINE GATE 5 6  
ALERT TONE SAMPLE 1 3 POST
ALERT TONE TX GATE 5 6,7  
ANTENNA RELAY ENABLE* 5 J801  
AUX +13.8V 2 LOTS J701, A++
BA* 0..3 4 LOTS  
BATTERY REVERT* 3 4  
BD* 0..3 4 LOTS  
CHAN ACT 9 3  
CODED MOD AUDIO 7 7  
CODED MOD AUDIO_1 1 7  
CODED MOD LEVEL* 4 J803  
CODED RX LEVEL* 4 J803  
COMPANDOR ENABLE 4 7,9  
CT AUDIO 1 J804 J804
CT SELECT   1  
DELAYED RESET 3 4  
DIGIT 1..3 3 1 DISPLAY
DISABLE* 5 5 LED
DISPLAY CHANGE* 3 4 SWITCH
DISPLAY ON 3 1  
DISPLAY SELECT* 3 4 SWITCH
DIVERSITY AUDIO 8 8  
DS* 4 LOTS  
EXPANSION RESET* 3 3  
FAST KEY 1 3  
FF ENABLE 4 8,9  
FF LEVEL* 4 8 EEPOT 1
FWD PWR 1 3  
GCC DATA AUDIO 7 7  
HSR signals 5 5  
IPCB INTERFACE 3 3  
LEVEL INC 4 7,8,9 EEPOTS
LEVEL U/D* 5 7,8,9 EEPOTS
LINE AUDIO 6 7  
LINE AUDIO SAMPLE 7 3 POST
LOCAL AUDIO 6 6  
LOCAL GATE 5 6  
LOOPBACK 5 8  
MAX DEV LEVEL* 4 7 EEPOT 4
MIC AUDIO 6 6  
MIC PTT* 3 4 J812
MOD AUDIO SAMPLE 7 3 POST
MPTSQ 9 1,5  
MRTI AUDIO IN 6 6  
MRTI AUDIO OUT 6 7  
MRTI AUX INDICATE 5 J802  
MRTI GATE 5 6  
MRTI INHIBIT 5 J802  
MRTI MONITOR* 3 4  
MRTI PL STRIP* 3 4  
MRTI PTT* 3 4  
MRTI RX CARRIER 5 J802  
MUTE 3 3  
NORMALIZED IF ENVELOPE 8 8 800/896 MHZ ONLY
OVERVOLTAGE ALARM* 3 4  
PA FULL POWER* 3 4 LED
PA KEY* 5 J801 LED
PA ON* 3 4 LED
PA POWER CUTBACK* 5 J801  
PL AUDIO SAMPLE 1 3 POST
PL DECODE DATA 8 3  
PL DISABLE* 3 4  
PL ENCODE AUDIO 1 7  
PL/CT 0..3 4 1  
PL/CT SELECT 4 1  
PL/DPL* 5 8  
PREDE/FLAT* 4 7,9  
QUAD AUDIO 9 9  
QUAD1 AUDIO 9 9  
QUAD2 AUDIO 9 9  
RAC_LN_AUD 6 6  
RAW RX1 AUDIO 8 8  
RAW RX2 AUDIO 8 8  
RAW TX AUDIO 6 7  
RAW/TX 7 7  
RCVR SQ LEVEL* 4 9 EEPOT 3
REPEATER GATE 5 6  
RESET* 2 3  
RESET_SWITCH* 3 2 SWITCH
RFL PWR 1 3  
RPTR SQ LEVEL* 4 9 EEPOT 2
RPTR UNSQ 9 3  
RX LEVEL* 4 8 EEPOT 5
RX1 AUDIO 9 6  
RX1 AUDIO SAMPLE 9 3 POST
RX1 GATE 5 6  
RX1 LOCK* 3 4 LED
RX1 LOOP 3 4  
RX1 STROBE 5 J801  
RX1 UNSQ 9 3  
RX1*/RX2 4 8  
RX2 AUDIO 6 6  
RX2 LOCK* 3 4  
RX2 STROBE 5 J801  
SA 0..2 4 J801  
SD 0..3 4 J801  
SECURE ALERT TONES 6 6  
SECURE RX AUDIO 6 6  
SEGMENT a..g,dec 4 1 DISPLAY
SELECT AUDIO 6 7  
SHUTSOWN* 2 J800 +5V
SPKR AUDIO 7 J812  
SQ ADAPT 5 9  
SQUELCH EEPOT ENABLE* 4 9  
SYSTEM AUDIO SAMPLE 7 3 POST
TKG MOD AUDIO 7 7  
TX AUDIO 6 7  
TX DATA AUDIO 7 7  
TX GATE 5 6  
TX LOCK* 3 4 LED
TX LOOP 3 4  
TX MOD AUDIO 7 7  
TX STROBE 5 J801  
VA (4.8V) 2 LOTS  
VB (4.8V) 2 LOTS  
VC (4.4V) 2 LOTS  
VD (3.8V) 2 LOTS  
VE (5.1V) 2 LOTS  
XMIT* 3 4 SWITCH

Expansion Connector J800 Signals:

This two-row connector is found on top of the plastic control tray, into which you can attach an expansion tray, a programming cable, or a metering panel.

PinSignal NameSrcDst
1 A++ 2 2
2 A++ 2 2
3 A++ 2 2
4 A++ 2 2
5 A++ 2 2
6 AUDIO GND 2 2
7 AUDIO GND 2 2
8 AUDIO GND 2 2
9 AUDIO GND 2 2
10 AUDIO GND 2 2
11 IPCB 3 3
12 EXPANSION RESET* 3 3
13 BA0 4 4
14 BA1 4 4
15 BA2 4 4
16 BA3 4 4
17 BD0* 4 4
18 BD1* 4 4
19 BD2* 4 4
20 BD3* 4 4
21 LOGIC GND 2 2
22 DS* 4 4
23 SHUTDOWN* 2 2
24 LOGIC SPARE 1 1
25 LOGIC SPARE 1 1
26 AUDIO SPARE 1 1
27 AUDIO SPARE 6 6
28 GEN TX DATA 1 1
29 QUAD 2 AUDIO 9 9
30 DIVERSITY AUDIO 8 8
31 GCC/RAC DATA AUDIO 7 7
32 SELECT AUDIO 6 7
33 LOCAL AUDIO 6 6
34 TX DATA AUDIO 7 7
35 RX2 AUDIO 6 6
36 TX AUDIO 6 7
37 AUDIO GND 2 2
38 RX1 AUDIO 9 9
39 QUAD 1 AUDIO 9 9
40 AUDIO GND 2 2

RF Tray Connector J801 Signals:

This two-row connector feeds signals to and from the RF Tray through a flat cable.

PinSignal NameSrcDst
1 +9.6V 2 2
2 RX2 LOCK* 3 4
3 TX MOD AUDIO 7 7
4 AUDIO GND (GND A) 2 2
5 RAW RX1 AUDIO 8 8
6 RAW RX2 AUDIO 8 8
7 ANTENNA RELAY ENABLE* 4 5
8 TX LOCK* 3 4
9 RX2 STROBE 4 5
10 PA FULL POWER* 3 4
11 AGC REF* (800/896) 8 8
12 PA ON* 3 4
13 RX1 LOOP 3 4
14 PA KEY* 4 5
15 RX1 LOCK* 3 4
16 POWER CUTBACK* 4 5
17 SD0 4 4
18 TX LOOP 3 4
19 SD1 4 4
20 SA2 4 4
21 SD2 4 4
22 SA1 4 4
23 SD3 4 4
24 SA0 4 4
25 RX1 STROBE 4 5
26 TX STROBE 4 5

MRTI Connector J802 Signals:

This single-row connector can either be 14 or 20 pins, and the layout is slightly different.

PinPinSignal NameSrcDst
1 1 LOGIC GND 2 2
2 2 MRTI PL STRIP* 3 4
3 3 LOGIC GND 2 2
4 4 MRTI MONITOR* 3 4
5 5 MRTI PTT* 3 4
6 6 LOGIC GND 2 2
7 7 AUDIO GND 2 2
8 8 MRTI AUDIO IN 6 6
9 9 LOGIC GND 2 2
10 10 MRTI AUDIO OUT 6 7
11 11 MRTI RX CARRIER 4 5
12 12 MRTI INHIBIT 4 5
13 --- N.C. -- --
14 14 MRTI AUX INDICATE 4 5
15 --- N.C. -- --
16 --- A++ 2 2
17 --- A++ 2 2
18 13 AUDIO GND 2 2
19 --- N.C. -- --
20 --- N.C. -- --

Secure Board Connector J803 Signals:

This two-row connector feeds the secure board that mounts on plastic standoffs on top of the SSCB board.

PinSignal NameSrcDst
1 AUDIO GND 2 2
2 AUDIO GND 2 2
3 +9.6V 2 2
4 SECURE RX AUDIO 6 6
5 TX AUDIO 6 7
6 RAW TX AUDIO 6 7
7 CODED MOD AUDIO 7 7
8 LOCAL AUDIO 6 7
9 HSR IN 4 5
10 LOGIC GND 2 2
11 HSR TO SECURE 4 5
12 LOGIC GND 2 2
13 HSR CLOCK 4 5
14 LOGIC GND 2 2
15 HSR SYN 4 5
16 LOGIC GND 2 2
17 BD3* 4 4
18 BD2* 4 4
19 BD1* 4 4
20 BD0* 4 4
21 BA3 4 4
22 BA2 4 4
23 BA1 4 4
24 BA0 4 4
25 DS* 4 4
26 N.C. 1 1
27 QUAD AUDIO 9 9
28 IN MRTI AUDIO 6 7
29 IPCB 3 3
30 LEVEL U/D* 4 5
31 LEVEL INC 4 4
32 CODED MOD LEVEL* 4 4
33 EXPANSION RESET* 3 3
34 SECURE ALERT TONES 6 6
35 CODED RX LEVEL* 4 4
36 N.C. 1 1
37 KEY BATTERY GND 2 2
38 CODED MOD AUDIO_1 1 7
39 +5V 2 2
40 AUDIO GND 2 2

TTRC Board Connector J804 Signals:

This two-row connector feeds the Trunked Tone Remote Control (TTRC) cards that install in the plastic control tray.

PinSignal NameSrcDst
1 A++ 2 2
2 AUDIO GND 2 2
3 9.6V 2 2
4 LINE AUDIO 6 7
5 TX AUDIO 6 7
6 RAW TX AUDIO 6 6
7 TKG MOD AUDIO 7 7
8 QUAD AUDIO 9 9
9 HSR OUT 4 5
10 LOGIC GND 2 2
11 HSR FROM TTRC 4 5
12 LOGIC GND 2 2
13 HSR CLOCK 4 5
14 LOGIC GND 2 2
15 HSR SYN 4 5
16 LOGIC GND 2 2
17 BD3* 4 4
18 BD2* 4 4
19 BD1* 4 4
20 BD0* 4 4
21 BA3 4 4
22 BA2 4 4
23 BA1 4 4
24 BA0 4 4
25 DS* 4 4
26 IPCB 3 3
27 CONNECT TONE AUDIO 1 1
28 EXPANSION RESET* 3 3
29 MUTE 3 3
30 GEN TX DATA 1 1
31 +5V 2 2
32 A++ 2 2
33 +5V 2 2
34 AUDIO GND 2 2

Forward/Reflected Power Connectors J806/J807 Signals:

These are female RCA jacks that are fed via coaxial cables from the forward/reflected power sensor present on 800 and 896 MHz and trunking stations. They are found on page 1 of the SSCB schematic and merely go through some op-amp buffers.

Control/Microphone Connector J812 Signals:

This 6-position, 6-contact (6P6C) modular jack is used for a local microphone, handset, or programming cable.

PinSignal NameSrcDst
1 LOGIC GND 2 2
2 AUDIO GND 2 2
3 MIC AUDIO 6 6
4 MIC PTT* 3 3
5 SPKR AUDIO 7 7
6 IPCB 3 3

DC Power Connector J701 Signals:

This large 6-pin Molex connector is the main power feed for the control tray.

PinSignal NameSrcDst
1 A++ (AUX +13.8V) 2 2,7
2 KEYWAY (NO PIN) --- ---
3 OVERVOLTAGE ALARM* 3 4
4 BATTERY REVERT* (AC FAIL*) 3 4
5 GND B 1 1
6 NORMALIZED IF ENVELOPE (800/896) 8 8

Contact Information:

The author can be contacted at: his-callsign [ at ] comcast [ dot ] net.

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This article first compiled 13-Sep-2006.


Article text and hand-coded HTML © Copyright 2012 By Robert W. Meister WA1MIK.

This web page, this web site, the information presented in and on its pages and in these modifications and conversions is © Copyrighted 1995 and (date of last update) by Kevin Custer W3KKC and multiple originating authors. All Rights Reserved, including that of paper and web publication elsewhere.