Coinvox 22

Project: Coinvox 22
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Description	Get an old payphone to work again
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synopsis

I got myself a Coinvox 22, reasonably cheap. The downside is: the inner workings have been stripped out, so it's just a metal box with keypad and display, a handset with hookswitch and a smalltransformer.

No coin mech, no ringer, no phone.

inside

handset / hookswitch

• 2 differend reed switches
• 4 coils
• 2 3-pin SOT 23 (smd) diodes(?) (D1, D2: A7 P 45)

J1

|o  spk
|o| mic -
|o| mic +
|o  spk

J2

mic+ 2 |oo| 1 spk
 spk 4 |oo| 3 mic-
 NC1 6 |oo |5 n/c
 NO1 8 |oo| 7 P1
  P2 10|oo| 9 NO2

Note: SW1 switches first (about 2mm) when hanging up

keypad / display

• IC2: PCF8576T (Universal LCD driver for low multiplex rates, I²C address 38h)
• IC3: PCF8574T (Remote 8-bit I/O expander for I²C-bus with interrupt)

  Addresses tied to ground; address 20h (r:41h/w:40h)

J

SCL 2 |oo| 1 SDA
    4 |oo| 3 
GND 6 |oo |5 VCC
    8 |oo| 7 
Int 10|oo| 9 

Display

• 8 &mul; 14 segment display
• 52 pins with the only the outer 9 connected (36)
• uses 4 backplane mode (all corners)

Keypad

	col1 (P7)	col2 (P4)	col3 (P5)	col4 (P6)
row1 (P1)	n/c	1	2	3
row2 (P1)	n/c	4	5	6
row3 (P2)	N	7	8	9
row4 (P3)	Vol	*	0	#

LGCO-CH BTC15 DESKII

4 431 4223 0 22

Sticker

Landis & GYR

412197580 A

Version.mec: A

Date fab : 02/95

plans

• upload reference material of the Coinvox phones (hacktic, 't klaphek, telephone museums ([1][2][3][4][5][6][7])
• experiment with my (front fed) coin mech (or look for a top fed mech that fits)
• experiment with a cisco phone (see if I can use the softkeys and the AUX port to read quarters or just Euro coins
• connect an ATA to an old phone

todo

• identify ICs, obtain datasheet, determine pinouts