DVTEL DVT-KBD – cctv keyboard controller

Connection and Operation

2 units repaired, both RS-232, one at 4800 baud one at 19200, both 8-1-n. 12V DC power, polarity doesn’t matter (internal bridge-rectifier).

On power-up the LCD steps through displaying the settings. Immediately after this display press MON then CAM to access the menu.  To exit the menu press CAM to reach option 8, then MON.


Number One : reported joystick not working, but keypad OK.

Joystick found to be OK, but the LCD would not always boot-up reliably when power applied.  General internal clean-up and it now seems OK. The problem was with the LCD rather than the main keyboard controller.

Construction has a plastic sheet clamped between the upper plastic housing and the button side (top) of the main pcb.  The main pcb is through-hole construction and apparently hand soldered with quite a lot of flux residue.  Quite a lot of the soldering from the bottom did not penetrate the through-holes to the top of the board.  Some of the component lead ends were quite long and interfered with the top plastic sheet.

Number Two : reported keyboard not working but joystick OK.

Most of the keys were not working, but the fault was intermittent.  This suggested other than a switch fault.  This keyboard contained more dust etc from general use.  To remove the plastic sheet and clean the top of the pcb required removing all of t he key switches and cleaning out the pcb holes – time consuming.  After a good clean out, cleaning of the pcb and switches, tidy up of some of the component soldering and rebuild, it is now working reliably.


Joystick – ascii codes transmitted via RS-232:

left  1La to 8La  8La to 1La backwards  analog 8-steps
right  1Ra to 8Ra  8Ra to 1Ra backwards  analog 8-steps
up  1Ua to 8Ua  8Ua to 1Ua backwards  analog 8-steps
down 1Da to 8Da 8Da to 1Da backwards  analog 8-steps
rotate-cw 1Ta 0Ta  switch only, not analog
rotate-ccw 1Wa 0Wa  switch only, not analog

Number pad – ascii codes transmitted via RS-232:

1,2,3,4,5,6,7,8,9,0 on LCD only under ENTER  
MON Ma numbers + MON

1Ma, 2Ma, 3Ma… etc.

5 digit max, eg. 12345Ma

CAM #a numbers + CAM

1#a, 2#a, 3#a… etc.

5 digit max, eg. 12345#a

right side pad – ascii codes transmitted via RS-232:

(n) : means a number entered on the numeric keypad appears here (less the brackets).

2×2 2Va ALARM EaIa or (n)Ea(n)Ia
3×3 3Va SPECIAL 9999Ea9999Ia
4×4 4Va FUN (n)%a
SEQ Ha CLEAR Ka (see note 1:)
LAST 2+a ACK (n)_a
NEXT +a FLIP 1:a

note 1: the clear key produces a RS-232 output if the LCD ENTER data is clear, otherwise it clears the LCD data and produces no RS-232 output.

left side small pad – ascii codes transmitted via RS-232:

(n) : means a number entered on the numeric keypad appears here (less the brackets).

RECORD ON/OFF 1*a or 2*a (toggles on/off) LOCK 1Ja or 2Ja (toggles on/off)
HOME 2:a MACRO (n)=a

left side small pad – ascii codes transmitted via RS-232:

AUX ON Aa (press), 0Aa (release) AUX OFF Ba (press), 0Ba (release)
FOCUS FAR 1Fa (press), 0Fa (release) FOCUS NEAR 1Na (press), 0Na (release)
IRIS OPEN 1Oa (press), 0Oa (release) IRIS CLOSE 1Ca (press), 0Ca (release)
LISTEN <a or 0<a (toggles on/off) AUDIO P.T.T. !a (press), 0!a (release)