CT24 CT25‎ > ‎

Tester 297

Tester 297


Tester 297 being used in the street, A blue hard hat should always be worn.

The Tester 297 is a handheld programmer for the GPT/Plessy type payphones,but was originally for programming the Coin Telephone 22B

In December 2019 PE says "It was developed by Autelca, Gumligen, Berne (German Speaking Switzerland!) for the Blue Payphone 1 - large stainless steel coin box, with RED LED display showing Minimum Fee, and money remaining etc.  This was known as the "Coin Telephone 22A" and was used in London Railway Termini, and a few airports.  The phone accepted UK Decimal coins: 2p  10p and 50p (if I remember correctly).  Minimum call fee was I think 8p.  All these settings were communicated to the telephone from the memory chip in the Tester 297.

When you plugged in a Tester, there was an initiation data exchange.  I think the Tester sent ^E (Hex 05) and the payphone responded with a code to say what model it was, what the latest tariff was in its memory etc. 

The Coin Telephone 22B came along soon after from Autelca, which was in the same type of metal case, and worked with the Tester 297.  The payphone had grey numerals (Liquid Crystal Display) to  advise the customer.  More widely used than the 22A.

Then the Landis & Gyr Cardphone 1A came along, and was designed to work with the Tester 297.  The Cardphone 1C (with colouring of front case and back case reversed when compared with a 1A) also used the Tester 297.  There were several thousand of those in service.

Now, we are coming to the Plessey Payphones.  The Blue Payphone 2 (Coin Telephone 24 or Payphone 600)  had the phone mechanism in its upper box, and the lower box was the cash container.  The Plessey payphones were generally designed to work with the Tester 297.  There was then the Payphone 500, similar technically, but with less armouring of the case,  Intended to be used inside buildings where supervised.  This also used the Tester 297.   By now, the Tester 297 could send ^E (Hex 05) or ^F (Hex 06) to say if it had enough tariff memory on board to enable 0800 and other free codes to be called with no money in the coin box.  I assume all but the CT 22A were updated to match the later standard.

There was then a cheapened version of the Payphone 600, the coin Telephone 34A, known as "The Low Take".  Not sure how that was programmed.

Finally, there were "Table Top" Payphones 100 from AGI in the UK, which had a new memory chip put in (instead of using Tester 297) and the Payphone 200, a wall-mounted version of the 100 design.  Plessey made a Payphone 300, being a smaller version of the 500, and that did not need a Tester 297
."

It contains 2 PCBs, the first has the processor, Eprom, Ram and interface circuitry


It has the same CMOS 8 bit  CDP 1802  processor as the Payphone, running with a 2Mhz crystal. 
The CDP1802 family of CMOS microprocessors are 8-bit register oriented central processing units (CPUs) designed
for use as general purpose computing or control elements in a wide range of stored program systems or products.
The CDP1802 types include all of the circuits required for fetching, interpreting, and executing instructions which have
been stored in standard types of memories. Extensive input/output (I/O) control features are also provided to facilitate system design.


At the bottom left of the processor board is a ZIF socket, with nothing in it.
At the top centre is an empty Blue 20 pin DIL socket marked SK1

The back of the micro board has a number of "mods"

At the very top of the board is a strip of 15 contacts that connect with the Display and Keypad PCB


The Back of the this board is fairly plain, the back of the switch contacts and LCD dirver ship can be seen.


The µPD7225 is a software-programmable LCD (Liquid Crystal Display) controller/driver.  The µPD7225 can be
serially interfaced with the CPU in a microcomputer and can directly drive 2, 3, or 4-time division LCD.  The µPD7225
contains a segment decoder which can generate specific segment patterns.  In addition, the µPD7225 can be used to
control on/off (blinking) operation of a display.





Comments