CHS-2 Handheld Terminal Unit (HTU)

© Brooke Clarke 2008

This is a small Handheld Terminal Unit (HTU).  It's part of the military Common Hardware Software program.  The idea being that computers can be customized by what software they run.  This is a 486 class CPU with 32 MB ram that uses PCMCIA for all the disks thus allowing for removable disks, probably as a security measure.   The DRS Technoligies Scorpion is the 2008 version.
Comparing the PSG-9 and the Scorpion

	PSG-9	Scorpion
Size	9 x 7 x 3.2	9 x 7 x 3.2
Wt lbs	4.2	8.5
Disp pix	640x480	800x600
RAM	32 MB	2 GB
DC Ext Pwr	8 V	28 V
Batt	BA-5600	BB-2600

These showed up on eBay for under $100.  Looking for any info on it.  Let me know.

There are two PCMCIA slots on the other side, one about 3.5" deep and the other about 5.5" deep.
Is there a way to load Windows in a PCMCIA card so the computer will boot from it?
There is a small PCMCIA internal hard drive (not in the externally accessible slots).
screen size is 6 1/8" wide by 4 1/2" high.
When an external monitor is used there is color info.  Don't yet know about the PSG-9 LCD.

Note the adjustments for LCD brightness and contrast work on the LCD hardware, not the external monitor.

5 May 2008 - I think the reason these computers were surplused is because they have an internal BIOS battery.  That it's soldered to the mother board is even worse.  And that it's not available is much worse.  The cost to the government to have a qualified person open the computer and install the BIOS battery would be staggering.  Afte the battery was installed then  the BIOS settings need to be restored.  Note when the BIOS battery goes bad you loose the use of the internal hard drive.
 12 May 2008 - I've received an email indicating that the switch shown in Fig 20  is to zeroize the BIOS.  When I found the switch I cycled it a few times to be sure the contacts were not oxidized and don't see how it could change anything since the BIOS battery is dead.  But now the BIOS does not run at power up. 
Also that J17, the 4 pin connector you can see inside the external PCMCIA access hole is for loading the BIOS.  If you know more please tell me.

BIOS Updating & the Switch & J17

Markings:
13973 ASSY 420001-105 SERNO 50336
13975 ASSY 420080-103 SERNO 1989

A Canadian eBay auction shows:

01-480-0622
014800622
7010-01-480-0622
7010014800622

The Canadian nomenclature CP-5131/GYC would follow the NATO naming scheme which would translate:

G	General Ground
Y	Data Processing
C	Communications

The PSG-9 nomenclature would translate as:

P	Portable
S	Special or Combination
G	Fire Control

Geoffrey Bunza wrote:
Comments on the PSG-9:
The PSG-9 uses a BA-5600  which has an 8.4V has center contact NEGATIVE outside contacts (half moons) are POSITIVE
& Longer cylinder 3 D LiSO2 cells vs. the BA-5800  which has 6.0V has center  contact POSITIVE and outside circular contact NEGATIVE
& Shorter cylinder 2 D LiSO2 cells.

 >From memory:
--The unit turns on by pressing both buttons on the front panel in the upper left and right simultaneously (hold down until turn on).
--If you have a bad screen you can connect a VGA screen to its 15 pin subminiature D connector.
--The small metal circular connectors are "Lemo" connectors (Brooke comment: I don't think so, Lemo connectors use a push on, pull off mechanism, not threads)
--It is essentially a slow PC architecture, the cardbus (PCMCIA) system is standard, but the boot setup is not, and can be configured by going into the BIOS setup (usual) (I don't remember the key sequence to get there)
--As a PC with only PCMCIA card disks (which includes the internal hard disk, by the way--only accessible by taking the entire thing apart) you can boot off of an insertable disk by first reconfiguring the BIOS to select it to boot. The PCMCIA insertable disk must be loaded elsewhere: find a laptop with a PCMCIA slot, and a floppy and/or a CD. Get a 1 or more GB PCMCIA drive or compact flash with PCMCIA adapter, load in your new found laptop, and put a bootable DOS image of system on the PCMCIA disk; then copy your OS of choice, that is likely the INSTALLATION CD, onto the PCMCIA disk. Insert the PCMCIA disk into the PSG-9, boot DOS or equivalent, and then start your OS installation. This needs to be done so your OS installer can recognize the internal configuration of the PSG-9 hardware.

If you can't boot DOS you have other problems-- either hardware or BIOS settings, or you didn't create a bootable PCMCIA disk.

Hope this helps.
--Geoff

There may be a way to either find or add an external power connection to the existing connector pins.  So opening up is the next step.

When the lid is removed what's under it is the LCD.  A glass panel comes off with the lid. To the right of the screen is the inverter transformer that's part of the CCFL backlighting.	This is looking up from inside when the keyboard is folded flat.
Fig 7 LCD after top removed	Fig 8 bottom of keyboard seen from inside
Fig 9 Back of connector sub assembly	Fig 10 Cavity in main box behind connector sub assembly

 I didn't notice any alien beings when taking these photo, but Fig 7 seems to show the reflection of one looking over my shoulder?  Fig 10 is the most interesting since there's access to the bottom of the battery compartment.  More later after the Fluke 87 does it's thing.

To remove the motherboard assembly after the top and connector assemblies have been removed, just lift it out.
It is possible to removve the motherboard addembly with the connector assembly installed, the ribbon cables that connect to the connectors are long enough.

Fig 15 Empty Box	Fig 16 Motherboard Assy
Red wire soldered to one of the 4 positive battery terminals. Black wire has a crimped ring tongue terminal with a 2-56 screw holding it.	The BIOS setting back up battery measures 0 volts.  The ICs have 1994 and 1995 date codes so it's (2008 - 1995) about 13 years old.  It's an ER10/28 3.6 Volt 1/2 length AAA.  I doubt a AA diameter will fit this corner that's beside the main battery compartment. The smaller board with one of the flex circuits connected is the power supply. There's another same size board under it. Note the black feet on the back side to protect the face of the LCD screen when it's set down. The small white connector on the main board near the upper left corner is probably the audio like would be connected to a CD player.
Fig 18 Card Cage Folded open exposing internal Hard Drive The Viper drive on the right I've added. The stock hard drive has the white label. CPU board on left of fled cables.	Fig 19 Back Up battery 1/2 AAA
Card Cage Folded to Reveal CPU board w/ sheetmetal cover in place & Mother Board Internal hard drive is PCMCIA Viper 260 MB marked "unclassified on white sticker	CPU, dead BIOS battery and just out of photo at right front mystry switch.
Fig 20 Closer View of Internal Hard Drive (left with white paper label) and added Viper Drive (or right)	Fig 21 CPU Board
Mother board                                                       ^                                                                          switch Do Not Operate Switch, Do Not Seperate Cards From Flex Connector. Doing either of the above may disable BIOS.	PSG-9 CPU Board w/o sheetmetal cover
Fig 20A PSG-9 BIOS load 4 pin connector
This may be the connector needed to load the BIOS.  It's very close to the switch shown in Fig 20 and the backup battery.
Fig 22 Short External PCMCIA Socket
Drive Locked into External PCMCIA Slot No. ? The metal tab should release the drive, but it's broken and the drive can not be removed.
Fig 23 Internal Viper 260 MB Hard Drive Directory

The battery is the BA-5600/U which is a negative center contact stick with three LiSO₂ cells or about 9 volts.
Saft data sheet for BA-5600/U, shows it's for the AN/PSC-2.

In addition to the dumb BA-5600 there are apparently some smart battery options for this computer.

BB-741/GYC, BT70341, (it's not clear what these numbers are: 420324-100, 842558-1).
In addition to the center negative contact and two half moon positive contacts there are four additional contacts:

A = CHRGPATH
B = MOD
C = +12
D = BATINFO

The BB-2600 (NSN 6140-01-467-5853, BT-70443) is a Li-Ion rechargeable. 
It has been replaced by the BB-2600A/U (NSN 6140-01-490-4311, BT-70743)
It does not have the ABCD smart battery contacts.  The gas gauge and charging contacts are on the cap end with the regular discharge contacts on the other end.


Fig 11 Battery Socket
Looking into the battery compartment.

The center contact is negative and is connected to the chassis, i.e. is ground and shows up on the metal case and a lot of places on the connectors.
One or more of the 4 contacts at the bottom will contact the half moon positive terminals no matter at what rotation a dumb battery is installed.

The four contacts at the top in a square pattern are recessed below the face and so will not be touched by a dumb battery. When a smart battery is installed it needs to be rotated so the projection matches the pocket.

Just to the left of this photo is the wall that's shown above in Fig 2 on the top.  The three dark green square shapes are thin panels that will rupture if the battery vents or explodes.  Just inside each of them the metal frame has eight holes that hopefully will allow gas to pass but stop large chunks from flying out.  There are some dead lined BA-5600 batteries that have exploded and for them the self discharge switch should not be pressed.

This is the same system used on laptop computers where the gas gauge has a serial port to report the batteries state of charge.  So I suspect the cells are Li-Ion.  If the battery can be charged while in the PSG-9 then there must be an external power input connector, WHERE IS THE EXTERNAL POWER INPUT? let me know
This may be the first military battery to have a smart gas gauge.  Many of them have LCD bar graph indicator gas gauges.

The M455-1/GRC-206 Power Source has an 8 Volt output for powering either this device or similar 8 volt computer type equipment.

Backup Battery

There is a 3.6 Volt  1/2 size AAA (9.7 mm dia x 25 mm long)  lithium backup battery with leads soldered to the motherboard.  See Fig 16.  This one is completely dead.  It's required if you want the BIOS settings to be remembered.  And that's required to set the hard drive Cylinders, Heads and Sectors.

Litton DC/DCPowerstick

Fig 12 Powerstick Connector & Heat Sink	Fig 13 Powerstick side veiw	Fig 14 Powerstick plug end
External end with connector for military vehicle power (20 to 30 VDC) which when dropped down to 8 will dissipate a lot of power if done with a linear regulator. This looks like a linear regulator with all the heat sinking and metal construction.	The cap at the left screws into the PSG-9 so the normal battery cover is left hanging on it's lanyard.	This end looks like the battery It does not contain the smart contacts so it's dumb.
photos courtesy of Kurt Lesser Kurt called this a vehicle battery adapter but I would call it a vehicle power adapter meaning there's no battery involved. Mike Murphy sells the power stick. <CTRL>F stick

Although J2 is in the same connector family as J3 they are keyed differently so you can not plug the external power cable (J2) into the keyboard/mouse jack (J3).
See Connectors below for photo of J2.

8 March 2008 - With 9 volts applied to the battery terminals (soldered red wire to one of the four battery socket pins after removing the connector sub assembly, Fig 10).  To the upper right and left of the LCD are a couple of momentary rocker switches (Fig 2)that have two bars at the top and one bar at the bottom.   When both of the bottom bars are pressed and held the computer boots up:
The green POWER LED turns on and the other LEDs do a dance. The LCD is showing a PhoenixBIOS DOS boot release 1.13.  At first I thought the LCD was dead, but when looking at a steep angle from below you can see the text.  Optimum viewing angle is 45 degrees below square on.  But it needs a contrast adjustment.

 Should the Fn+F4 and Fn+F5 controls work in the PhoenixBIOS or is this part of some higher level language (Fig 4 Keyboard)?
Note:  on the keyboard there is a white box surrounding each key.  Those icons without a box are just labels above the function keys.  The upper right key toggles the keyboard illumination on and off.  But to see the screen the desk lamp is supplying the light.

Maybe the CCFL lamp is bad????

PhoenixBIOS(tm)A486 Version 1.13
Copyright (C) 1985-1992 Phoenix Technologies, Ltd.
All Rights Reserved
    Release 1.13
486 DX2
37C51 Revision: V1.2
XICOR Revision: 1.13
Initializing PCMCIA Disk Interface
Initializing IDE Disk Interface
Fixed Disk 1 Failure
Performing Cache Test & Configuration
Cache 1 Enabled
Invalid configuration information - please run SETUP program
Press the F1 key to continue, F2 to run the setup utility

F1:
FDI Modem Presence Check:
Passed
Missing operating system

<CTRL><ALT><DEL>
screen above
F2:
Phoenix SETUP Utility (Version 1.00)
(c) Phoenix Technology Ltd. 1985, 1992  All Rights Reserved
page 1 of 2
** Standard System Parameters **
Diskette A: Not Installed   Cyl   Hd   Pre   LZ   Sec   Size
Boot Disk 0:   Type  3      615    6    300    615    17    30
         Disk 1    Type 1        306    4    120    395    17    10
Internal Disk:   Boot Disk 0
Base Memory:   640 KB              PCMCIA Slot:      Slot 2
Extended Memory   31744KB     PCMCIA HDD Type: Ministor
Speaker Control:   Off                  Numlock on at boot: NO
Cache:                  Enabled            Quick Boot: Off
Default Contrast: 11                     External Monitor:   On
Page 2 of 2
Power Management: AC Disabled
System Idle After:   3 Seconds          System Idle Speed:   Divide by 8
System Standby After:   6 Minutes   System Standby Speed:   Stopped
System Suspend After:   10 Minutes   Hard Disk Off After:   5 Minutes

<F2 SysInfo>
page 1 if 2
Processor Type:   80486 SX
Coprocessor Type:   80387 or compatible         Option ROMs Found:
Reserved Memory:   Not Installed                           No Option Roms found
BIOS Version:           1.13
Video Mode:              03h
Serial Ports:               03F8h  02F8h
Printer Ports:            0378h       
? page 2?

Questions:
1) what does video mode 03h mean?
2) what operating systems can be run on a 80486 SX with 32 megabytes of memory?
3) is there any mouse or touch screen support?
4) is this a special BIOS that has built-in PCMCIA support?  My WIN XP BIOS does not.

CCFL Back Light

After the boot process the screed went dark.  I thought the CCFL power supply was defective,hence this paragraph. 

10 Mar 2008 - This is normal operation.  When using J2 to provide external DC power the screen looks normal during the BIOS part of the boot, then switches to the poor contrast mode.  That may be because of the contents of the existing hard drive.  For example the hard drive software may configure the screen improperly.

Fig  17 CCFL circuit


Just to the left of the white 5 terminal input connector the board is marked:
420067
L1-A
At the green plug into the white connector at the left I'm calling the top pin #1

Pin	Ohms to Gnd	Volts
1	1.3 M	8
2	0	0
3	14.5 k	0
4	3.5 k	0
5	1.6 M	0

The lamp is 3 mm dia x 128 mm long.

The design is based on Linear Technologies LT1172 100kHz, 5A, 2.5A and 1.25A High Efficiency Switching Regulators and very close to  App Note 49 Fig 2 & D-1.
The full primary of the transformer has a data sheet resistance of 0.19 Ohms (center tap half that) and the feedback windings are 0.084 Ohms each so it's difficult to make resistance measurements.  Instead of the half bridge transistors specified in the app note some Zetex parts were used.  The Zetex parts are specified to have ten times lower Vces.

2783384  ELECTRICAL INVERTER CIRCUITS, R.L. Bright & G.H. Royer, Feb 26 1957, 331/113A ; 290/4R; 307/401; 331/181; 363/133 - magnetic saturation of the transformer is a key parameter.

The LT1172 (U1) has it's Vin pin wired to connector J1 pin 3 and not to the +8 volt supply, maybe as a way to disable the LCD?
To check the inverter the switching output pin of  U1 or the emitter of either Q1 or Q2 can be grounded.  This turns on the CCFL even when the lid is has been removed.   When testing after starting the computer the lid can be disconnected and the computer continues to run.

I've tried pulling J1 pins 3, 4 & 5 up and down one at a time (I don't have enough hands to do more, and no single pin will turn on the CCFL.  Note the Royer patent shows that a couple of transistors, a special transformer and a source of DC are all that's needed to make an inverter.  The 1172 is there to regulate the current and control the brightness, i.e. lamp current.

The short bars above the starting longer bars are the navigation buttons.  The screen is VGA color, so some flavor of Windows should run.
Also in a military environment a mouse does not make sense.  Win XP requires a minimum of 256 MB of RAM and so is way too big.
WIN 3.1 would fit and WIN 95 or WIN 98 might fit.
DOS 6.n makes the most sense.

14 March 2008 - waiting for PCMCIA hard drive.
4 April 2008 - the PCMCIA hard drives have been here for some time.  But when I tried to put them into my laptop - no go.
The hard drives are Type III, i.e. 10 mm high and would not fit.  So eBay had a PCMCIA to PCI adapter advertised with the words "works with Type I, II or III cards and the photo showed a tall slot, BUT when it came the slot was about 6 mm nowhere near 10 mm.  Well after returning it today received an email refunding my purchase.  I have a feeling that most of these adapters advertised as Type I, II, III are only good for the 5 mm cards unless there are explicit words stating otherwise.

looks like Viper mechanism with alternate interface packaging

ID	Contacts	Description	Function
J1	55	military circular connector, external screw threads, shrouded male pins, #/row= 3, 6, 7, 8, 7, 8, 7, 6, 3	Dual Modem 1
J2	7	circular connector, external screw threads (not push on LEMO) What are these connectors & where to get plugs?	External DC Power
J3	7	"	PS2
J4	15	DB-15-f	VGA Video Mon
J5	9	DB-9-m	COM1
J6	25	DB-25-f	Printer/parallel
J7	9	DB-9-m	COM2
E1 & E2	2	wire line spring binding posts	protocol 2

Note 2 -for single channel communications.

Fig 33 J2 Connector
The connector with the cap off is J2 used for external DC power.  It has 7 terminals (hard to say if they are male, female or both). 

The mating plug will have a body diameter of about 0.216" and 3 projecting lugs.
What is this Connector?

22 Mar 2008 - This shows the hot wire mod to get power to J2 until the proper connector is located.  A couple of tie wraps to take any strain off the solder only joint.  With this connection you can see the BIOS boot then the LCD goes into invisible mode.


I started to use my laptop to load a PCMCIA hard drive, but the laptop only accepts the Type I cards (5 mm) and the hard drive is a little over 10 mm high.  A PCI card for the desktop  is on order.
Just above the second bottom philips head screw from the right there's a SMT version of a TO-220 package that contains a 340 power Schottky diode  with it's anode connected to the same terminal as the red wire and it's cathode connected to the big connector just above it.  The 8 lead IC just to the right and up from the 340 may be a power transistor.   All four top pins are connected to the battery positive pin and the lower left three pins are connected to the same row of pins on the big connector as the BD340 diode.  There's a SOT-23 FET just to the left of the BD340 that connects to the lower right pin on the 8 lead package.  These parts form the selection circuit that uses the external power as a primary supply and if it fails switches over to the battery.

When the keyway is at top center the PSG-9 pins are numbered left to right 1, 2, 3 for the first row, 4 through 9 for the second row, etc.
The SINCGARS (RT-1439) (also see U-229 family Pin Out) cable is wired:

SINCGARS DATA Conn	SINCGARS Function	PSG-9 J1	PSG-9 Function
A	Ground	31, 43, 55	Ground
B	Spkr data out	50	Data In
C	PTT	2	Key Tx
D	Mike In Data In	12	Data Out
E	Digital Data Mode Select	7	Set D. Mode
F	Analog Data Mode Select	9, 42	Set A. Mode

There are two button groups to the left and right of the screen.
When the two bottom bars are pressed and both held for about 1/2 second the power comes up.
The shorter bars above those are used for screen navigation.
The LCD screen is 4.5" hi by 6" wide, about a 7 3/8" diagonal 640x480 VGA color

When the keyboard/LCD cover is closed the 4 indicator LEDs are still visible:
POWER
BAT LOW
CAPS LOCK
WARM UP

The internal modem supports the Ground/Vehicle Laser Locator Designator (G/VLLD) IAW MIS 34269F over a high speed synchronous data port.

STANAG 4202 Transmission Characteristics for Data Exchange between Land Tactical Data Processing Equipment over Single Channel Radio Links
MIL-STD-188-110A Interoperability and Performance Standards for Data Modems ACCS-A3-407-008C Interface Specification for the Army Data Distribution System (ADDS) Interface This seems strange.  I would expect the PRC-77 and VRC-12 to have the same capability as far as data is concerned, but not the PRC-126 since there's no mil std connector that gives acess to the wide band capability, it can only be used with the KYV-2/SVM-68.  All SINCGARS radios have a number of data modes and so might be in multiple catagories.

All the manuals are in the "D" folder and so are not public information at this time.

TB 11-7021-228-10-1

TB 11-7021-228-10-2   

TB 11-7021-228-10-3

TB 11-7021-228-10-4

TM-9-6675-349-12-P

TM 11-7021-225-12&P

IPADS

The same Canidian eBay seller that was selling the PSG-9 also had this printer.  Maybe they are related and manbe not?

It's 7 x 7 x 5 inches and the roll paper is 4 1/4" wide and I'm sure it's dot matrix to support both text and graphics.

Controls and Indicators

On the front there is a combined ON-OFF switch that's also a circuit breaker.  When switched on with a battery installed the LEDs flicker and go off and the paper feeds.
LEDs for:
ON LINE
POWER
FAULT
LOW BTY
Two push buttons:
TEST - prints a test pattern
LF - Feeds a line of paper
When LF is pressed and held and TEST is also pressed (BRIGHT) the POWER ON LED brightenes and it seems continionous paper is fed.  That may be a problem or may be related to not having anything connected to the data input.

Connectors

On the back there are two connectors and a tapped hole for a ground marked E1 GND.
Circular bayonet locking.

J1 POWER

MS3470W14-5P
5 male pins in a "W" shape. 
Pins marked A, B, C, D, E & F
[ cap MS3181-14CA]

The J1 POWER connector has a low diode drop from J1-A to battery pin 5 and from J1-C to battery pin 5.  Battery pin 5 is the "A" side positive terminal.
J1-B connects to J1-D and these connect to battery pin 3.  Battery pin 3 is connected to battery pin 1 ("B" side minus) only on rechargable batteries and so is a selective way of charging only rechargable batteries and not charging primary batteries like the BA-5590/U.  Battery pin 2 is jumpered to pin 4 so the battery is being used as a 24 volt (30 V full charge/fresh to 10 volt dead).

29 March 2008 - my day one guess is that B & D are ground and A & C are +28 VDC.

J2 DATA

MS3470W10-6P
6 male pins.
Pins marked A, B, C, D, E & F
[cap MS3181-10CA]

There are 6 wires from the back of J2 they are (in pin number order) Wht, Blk, Wht, Blk, Wht, Blk.
Pin 1 on PCB is J2-A and Pin 6 on the PCB is J2-F

Battery

The internal battery is one of the BA-5590 family.

Fig 34 Printer Battery Compartment

On the left side there are two screws that can be backed out a few turns then the battery door slides to the left (no need to remove the screws). A BA-5590 battery is connected to the cable plug and the plug end fed in first.  My 5590BA will also work. I have the cover off which had three seals that were already broken.  Front is to the right of this photo.  The PCB to the right is the printer driver and the PCB near the battery is the power supply.   There are 5 wires going to the battery so it may support rechargable batteries like the BB-390, BB-590, BB2590, etc. when external power is used.

Printer Test

Fig 35 Printer Test Strip

The alpha numeric characte set inncludes the upper case letters, lower case letters, digits and 23 symbols for a total of 85 characters.  The test is 41 lines long and there are 40 characters across the strip.

Serial Printer Connector Normal Computer DB-9m connector:

Pin	Name	Dir	Volts
1	DCD	in	+0.1
2	Rx	in	+0.1
3	Tx	out	-10.3
4	DTR	out	-10.3
5	ground	gnd	0
6	DSR	in	+0.1
7	RTS	out	-10.3
8	CTS	in	+0.1
9	RI	in	+0.1

Note that the direction of the signal (Dir coul) is exactly correlated with the open circuit voltage on the pin.

Serial Printer DB-9f (HP LaserJet 4050)
This table has all the directions opposite of those in the computer table above.
Some of the names may be wrong.

Pin	Name	dir	Volts
1	Data Carrier	out	+6.8
2	Tx	out	-6.4
3	Rx	in	0
4	Terminal Ready	in	0
5	ground	gnd	0
6	DSR	out	+7
7	CTS	in	0
8	RTS	out	+6.9
9	Ring Indicator	out	0

A minimal connection would be pins 2, 3 and 5.  The next most common would include CTS/RTS so would have pins 2, 3, 5, 7 & 8 which is 5 pins and so may be what the CA-5033 uses.
The HP LaserJet has the following voltages for those 5 pins: -6.4, 0, 0, 0, +6.9.

CA-5033-J2

Blk v   Red->	A	B	C	D	E	F
A	x	+9.6	+18.9	+9.6	+9.6	+9.6
B	-9.6	x	+9.3	0	0	0
C	-18.9	-9.3	x	-9.3	-9.3	-9.3
D	-9.6	+9.3	+9.3	x	0	0
E	-9.6	0	+9.3	0	x	0
F	-9.6	0	+9.3	0	0	x

The A-C voltage of almost 19 seems too high so the ground pin is not A or C.
The data is symmetrical about the diagonal.
Looking for rows that have three zeros and one each + and one each - voltage yeilds:
B, E or F as possible ground pins.

Fig 40

Fig 41

Fig 42

PSG-2 Digital Message Device PSG-5
PSC-6 Digital Imaging Set -