Download The Split printers, as supplied, are powered by 24VCD supplied

Running a POS Fast Split Printer from Batteries
The following contains my experience of adapting two POS printers to run from two small 12VDC
batteries, one for use by SWOC another for use by SBOC. Both of these printers have been running
successfully for many months. However, anyone following these instructions does so at their own risk.
I can not take any responsibility for any failure with your printers.
A small amount of soldering is required to make the various connections.
A voltmeter with continuity tester (ohmmeter) is essential. (A small electrical meter is available from
Maplin, (Stock No N20AX) for around £9)
OverView:
The Split printers, as bought, are powered by 24VDC supplied from a power pack, either external or in the
case of the Citizen CBM1000, held within a tray screwed to the printer base. The power pack output,
24VDC, is fed to the printer by a male DIN 422 plug, see fig 1. Sourcing these was a major obstacle. I
eventually found them stocked by a Polish company TME (www.tme.pl).
To avoid repeatedly inserting/removing this plug from the printer I have included an in-line low voltage
power connector between the DIN plug and the batteries, {see below Mechanical Connection of Data &
Power Leads to POS Printer}.
Apart from the DIN 422 plug all other components can be obtained from Maplin or similar suppliers.
There are 3 possible ways to construct the power lead feeding into the printer:1.
Using an existing DIN plug, including about 25cm cable, with a new female DC power socket.
2.
Using an existing female socket from an old SI Master station and a new DIN plug.
3.
Using a new DIN plug and a new female DC power socket.
(I have constructed leads using each of the above combinations)
Male Din 422 Plug.
There are two possible sources of these:1.
The DIN plug can be cut off the end of the low voltage power cable. Leave enough cable, about
10”/12” (25cm/30cm) to allow the lead to be taped to printer body, {see Mechanical Connection
of Data & Power Leads to POS Printer}, and for attaching the in-line power socket. If you have
an old, broken POS printer then its DIN plug is ideal; alternatively the DIN plug can be cut off the
end of working POS printer low voltage power lead. A replacement male DC power plug,
matching the one put on the end of the battery pack cable, can be soldered on to the now exposed
low voltage lead; thus allowing either the battery pack or mains power pack to be used.
Cutting the low voltage power cable revealed a screening foil and wire in addition to the expected
internal power wires. I suspect the screening is there to shield the printer from induced stray
electric currents which might arise within a shop’s environment, e.g fluorescent lights, power to
the till, etc. The screening is connected to the Earth on the incomings mains power plug.
I found it difficult to work with this flimsy shielding foil and wire so trimmed them out of the way.
This will avoid them shorting on the soldered joints. To date no problems have occurred as a
result of this lack of shielding.
2.
Male DIN 422 plugs can be obtained from TME in Poland. {Incidentally they also stock the
bleepers used in the SI units.} The plugs cost 1.86 euros + VAT, the downside is the P&P at 9.90
euros +VAT. If enough interest is shown I could place a collective order.
In-Line Low Voltage Power Connector.
These, along with most other components, can be sourced from any Maplin’s Store.
If you have any old type SI Master unit and never use the external power lead for attaching to an
external power source, then this female socket can be detached for use as half of the in-line power
connector. To detach this female socket from the master unit unscrew the casing of the 9-pin serial
plug and cut the white and brown wires. This gives an already soldered connector on a suitable length
of cable. Make sure the ends of the remaining cut wires cannot short themselves.
Connector Polarity: I decided that the positive wire would be carried on the central pin/socket of the inline connectors. This decision is arbitrary; but used consistently with all 3 connectors I’ve made.
Mechanical Connection of Data & Power Leads to POS Printer
Our original Citizen POS printer failed and was producing garbage. It had a parallel connection
and analysis showed that 2 of the 8 lines were being held at a fixed setting and not responding to the input
from the computer. I concluded the fault lay on the POS printed circuit board at the connection between the
socket and circuit board; unfortunately given the construction of the circuit board it was impossible to do a
DIY repair, and was uneconomic to get it repaired by the suppliers.
I suspect that the mechanical strength of connections, both power and data, to the printed circuit
boards is not too robust. Perhaps this is not unexpected since the vast majority of users of these printers
(shops) will connect them up once only and seldom move them, so the manufacturers will not overengineer these contacts.
However, when orienteers use these printers they are continually moved around and often the
leads, power and data, are repeatedly inserted/removed.
In an attempt to avoid possible problems with unnecessary mechanical forces on these connections
I have taped the data (USB) and power leads to the back of the printer.
Assembling the Power Pack Leads.
Initial Voltage Check on Original DIN Plug
Before starting the project the pin voltages should be checked on the existing DIN plug whilst powered by
the mains power pack. Hold the DIN connector steady and use a voltmeter to check the voltages between
the 3 pins, A, B & C, and surrounding metal part of the plug, D, see fig 1.
These should be:A to B
+24/25VDC (I.e pin A is +24V/+25V relative to pin B)
A to D and B to D
no voltage; though a small decaying voltage may show.
A to C, B to C, D to C
no voltage
I.e Pins A & B carry the power; pin C ensures correct orientation when inserting the plug.
Because D is connected to the common mains earth connection a small voltage appears when
initially connecting a voltmeter; this decays rapidly to zero.
Once the wiring of the new DIN plug has been completed and before connecting to the printer, the pin
voltage should be checked again, this time using the battery pack as the power source.
Wiring a new DIN plug.
These plugs come in 9 parts, see fig 2, with NO assembly instructions!
1.
Before soldering the wire to the plug pins ensure the 4 components shown in fig 3A are threaded
on to the cable. {If there is not yet a connector on the other end of the cable these can be slid on later. }
2.
Solder the two wires of the cable onto the component with the socket pins, fig 3B.
a.
It is essential that the soldered joints are both mechanically and electrically sound; once
assembled the plug cannot be disassembled (at least not with any ease).
b.
It is possible that the insulation on the wires melts back further than intended whilst
soldering, exposing more bare wire. To avoid any possibility of these bare wires coming
into contact with each other or the metal casing holding the plug, it may be necessary to
wrap some insulation around these exposed wires. {This was not necessary in fig 3B, but
was on an earlier lead I made. Also note if you are using the leads from an old SI Master
unit the brown wire has been soldered to the outer contact of the female socket, so with
my wiring convention becomes the negative wire when soldering this joint}
3.
Fig 3C shows, in the correct orientation, the soldered pin connector and metal sleeve prior to
insertion. Use a continuity tester to check that the wiring to the pins is correct before proceeding.
The plug should fit into the sleeve just one way round, but since the sleeve has a dividing cut
along its length it is possible to force the plug in but incorrectly orientated. When correctly aligned
push the plug firmly in, there are 3 small metal barbs that will hold it firmly in place. Fig 3D
shows the plug after insertion into the sleeve.
4.
Slide the plastic ring down over the sleeve, figs 3E & 3F
5.
Use the small metal cable clamp to crimp the cable to the metal sleeve, see figs 3G/H/I. This
protects the soldered joints from being subject to any mechanical pull on the cable. Ensure the
cable between this clamp and the soldered joints is not tight before crimping.
6.
Now put the small section of the metal sleeve into place and bring the metal spring down over the
now complete sleeve, fig 3J. Fig 3K shows part of the outer cable covering in place. It will only
slide onto the metal sleeve if correctly orientated. A barb on the small section of the metal sleeve,
which has just been added, engages with this covering; it’s on the underside of fig 3K.
7.
The cable I was using was far thinner than the hole in the end of the final bit of cable covering. To
make this a tighter fit and hence avoid unnecessary movement of the cable within the plug I
wound some self-amalgamating tape around the cable at the position it would exit the covering,
see fig 3L {Self-Amalgamating tape is thicker than ordinary electrical insulation tape. It has the
property of sticking to itself so doesn't unwrap like ordinary electrical tape.} The final part of the
covering is then brought down and engaged with the existing section; a small screwdriver was
needed to force the lugs into place, fig 3M.
8.
Finally the remaining part of the plug cover is slid into place, see fig 3N. This part only fits when
correctly oriented, and once inserted is held in place by barbs.
9.
Fig 4 shows a completed cable where the in-line female connector from an old SI Master unit.
In-Line Plug & Socket.
Compared with the DIN plug these are very straightforward to assemble. I used male plugs on the
battery leads and female plugs on the DIN plug leads, though this is arbitrary. The positive wire red (or
brown) was soldered to the centre pin and socket, again this is arbitrary.
Before wiring up the in-line connectors do a continuity test to check that pin A of the DIN plug,
see fig 1, is connected to the pin/socket of the in-line connector you are using for the positive supply
voltage. If this is not the case then by swapping the wiring at the in-line connector will correct this polarity
error; dismantling the DIN plug is extremely difficult and a lot of hassle.
However, ensure that the wires from the male plug to the batteries follow the standard convention
of red (or brown) to the + terminal and black (or blue) to the negative terminal. These may be visible to
other users and must NOT cause confusion when connecting to the batteries.
Use a Male plug/Female socket from Maplin, see list of components. If you are using the female
socket from an old SI Master unit you will need a ‘Long DC Power Plug 2.1mm/5.5mm’ (Maplin Code
HH61R).
Battery Connections:
The two batteries were strapped together using electrical tape. There are small rectangular slots on the
top of the batteries, I believe these may be relieve vents in case there is a build up of pressure whilst recharging, so avoid covering these with the tape see fig 5A
Use 5mm female spade connectors, see components. They come in packs of 10, different colours are
available. Although only 4 are needed, I felt it would avoid future confusion to buy a pack of red and a
pack of blue so their colours follow the conventional wiring colour-code. Fig 5B shows one of the spade
connectors to a battery terminal – the white electrical tape is to avoid the terminals getting shorted
accidentally.
In Figs 5A/B the twisted pair of red and black wires between the middle blue and red spade
connectors provides the serial connection of the two batteries to produce the required 24VDC. On each
battery between its terminals are connectors used for re-charging the batteries, more details see below.
All these wires are twisted pairs to reduce the electrical resistance of the connections.
Battery Re-Charging:
The charger comes with spade connectors on its leads. These would be awkward to use; it will involve
removing the connectors from the battery terminals every time the batteries need re-charging. To simplify
this process two female sockets {see Components: Re:Charging Sockets} have been permanently
connected as shown in figs 5A/B/C/D. A corresponding male socket was attached to the battery charger
leads, in place of the spade connectors with which it is supplied, see fig 5D
A simpler and cheaper alternative would be to put small crocodile clips, one red, one black {see
Components: Re:Charging Sockets} on the end of the battery charger leads; these can then be clipped to
each batteries terminals in turn, without the need to remove the battery spade connectors from the battery
terminals.
NB The battery charger is for a 12V battery, so the two batteries have to be re-charged separately
FINAL CHECK:
Before using the leads connect them up to the batteries and RE-CHECK the voltages between the
various pins and metal part of the socket, see fig1. These should be the same as in the original check,
though there might be a slight difference (+ 1VDC) in the voltage across pins A & B, but their POLARITY
MUST BE THE SAME AS IN THE ORIGINAL TEST.
Components:
Batteries:
Rechargeable Sealed Lead Acid Battery, 12V, 1.2AH
Source: BatteryMasters: (Yuasa batteries) £8.51 each + £5.75 P&P
£22.77
{Much cheaper than similar batteries from Maplin}
Supplies from Maplin:
Charger for Sealed Lead Acid Battery (Stock No LL30H)
£21.99
Re-charging sockets, similar to shown on figs 5,
Male (pre-wired) (Stock No JG04E) £2.79 each
£5.58
Female (pre-wired) (Stock No JG05F) £2.79 each
£2.79
{Without pre-wired, as used in figs 5, these cost £2.19 each}
Alternative to above sockets:
Crocodile clip (Red, FM37S) (Black, FK34M)
£1.09 each = £2.18
Female Spade Connectors (packs of 10) (Red, N35CY) (Blue, N36CY) £1.59 per pack
£3.18
In-Line Male Plug:
Long DC Power Plug 2.1mm/5.5mm (Code: HH61R)
£1.49
In-Line Female Socket:
2.1mm (Code JK11M, £1.89)
£1.89
Maplin Total
£36.92
Self-Amalgamating Tape
TLC Ltd (www.tlc-direct.co.uk) : Part No: TL SAT19 5m roll, 19mm
£2.57
Or Maplin (code: KW29G)
£8.99
TME (www.tme.pl)
Mini DIN 422 DC 3 pin (Stock No: PC-MDP-401-3P)
1.86 euro +VAT
P&p
9.90 euro + VAT
{If there is enough interest I am willing to place an order for 10 or more of these which would bring the
cost down to around £3.60 per plug. If more than 10 are order the price per plug will be less. I would
recommend anyone ordering these plugs to get at least one spare in case something goes wrong with its
assembly. Let me know if you are interested in this option}