Star Tech Journal

STAR*TECH JOURNAL/SEPTEMBER 1983
19
ATARI
TECH TIPS:
* AMPLIFONE COLOR X-Y MONITOR VOLTAGE REGULATOR CIRCUIT
* TEMPEST WELLS-GARDNER X·Y MONITOR IPC BOARD MOD
Ampllfone Color X-Y Monitor Voltage Regulator Circuit
Atari PIN A200000-01
On some Gravitar and
Quantum games using the
Amplifone Display, the VRl
(7824) and the VR2 (7924)
on the High Voltage PCB may
be overstressed during power
up or power down.
Before replacing VRl or
VR2, check that blocking
diodes CR5 and CR6
(1N4001) have been
incorporated in the circuit of
your display (see Figure 1). If
not, perform the following:
1. Install a diode (31-
4001) from pin 3 (+24v) of
VRl (7824) to ground;
position the cathode end at
pin 3.
2. Install a diode (31-
4001) from pin 3 (-24v) of
VR2 (7924) to ground;
position the anode end to pin
3.
3. Replace the associated
electrolytic capacitor.
Note: Unless otherwise
specified -
1. All resistor values are in
ohms, ¼W, 5%
2. All capacitor values are in
uf.
WARNING
Components identified by
shading have special
characteristics important to
safety and must be replaced
only with identical parts.
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