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SERVICE BULLETIN ML 0028

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SERVICE BULLETIN ML 0028 Powered By Docstoc
					SERVICE BULLETIN ML 0028
 Date              : April 25, 2002
 Game              : Timebuster
 Subject           : Watchdog Modification

 Distribution :-   Service Bulletins are available at www.laigames.com and are e-mailed to
                   members of a opt-in e-mail list. If you wish to receive Service Bulletins via
                   e-mail, send an e-mail to Wesley@mleisure.co.id to subscribe to this list .

Problem            : Watchdog Circuit fails to reset the game if the MPU does not
                     run on power up. This is because the current Watchdog
                     circuit needs the MPU to drive the Watchdog Pulse low at
                     least once before it will reset.

Solution           : The following modification to the Watchdog Circuit will
                     eliminate the need for the MPU to drive the Watchdog Pulse
                     low once for a reset.

Instructions : Follow the step-by-step instructions below and refer to the
               photos on page two. The Watchdog PCB is located on the
               lower left-hand side of the Timebuster machine and is
               accessed through the back service door. See page 28 of
               your Timebuster Manual for more information.

                                       Parts Needed
                         1x        4.7uF Electrolytic Capacitor (>=16v)
                         1x        10K ohm 1/4w Resistor
                         2x        Diode 1N914 or Equivalent
                         10cm      Heat Shrink Tube 3mm
                         1cm2      Electrical Insulation Tape

   1. Solder the negative lead of the 4.7uF electrolytic capacitor to the
      ground plane where the existing 4.7K ohm resistor is soldered
      (see step 1 photo)

   2. Solder one of the 1N914 diodes (or equivalent) with anode connected
      to pin 2 IC555 and cathode to positive terminal of 4.7uF electrolytic
      capacitor. Insulate the cathode lead with some heat shrink tube.
      (see step 2 photo)

   3. Solder the 10K resistor in parallel with the 4.7uF electrolytic capacitor.
      Place some insulation tape beneath the joint to prevent shorting.
      (see step 3 photo)

   4. Solder the remaining 1N914 diode (or equivalent) cathode to the
      collector of the 2N4401 transistor closest to the fuse. Solder the anode
      of the diode to the positive lead of the 10uf electrolytic capacitor.
      Insulate the diode leads with some heat shrink tube.
      (see step 4 photo)

Regards
LAI Games
                                           BEFORE




                        STEP 1                STEP 2




                        STEP 3                STEP 4




NOT SOLDERED TO PCB FREE FLOATING
PLACE INSULATING TAPE UNDERNEATH

                                           AFTER




                           ML0028 Page 2

				
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