Stern Pinball AC/DC Service And Operation Manual page 71

OPTO TROUBLESHOOTING
1. VOLT METER TEST (INDICATES NORMAL OPERATING CONDITION):
A. OPEN OPTO (Light Falling on LED) = SWITCH OPEN. Place meter leads across points A and B on the LED1 Circuit (Refer to
Schematic Drawing on previous page, 520-5174-00 Receiver Side). It should read approximately 0.8 - 1.2v DC. The LED2 Circuit
operates the same.
B. CLOSED OPTO (Ligth Blocked) = SWITCH CLOSED. Place meter leads across points A and B on the LED1 Circuit (Refer to
Schematic Drawing on previous page, 520-5174-00 Receiver Side). It should read approximately 0.0 - 0.1v DC. The LED2 Circuit
operates the same.
2. OSCILLOSCOPE TEST (INDICATES NORMAL OPERATING OCNDITION):
3. BENCH TEST (SEE FIG. C):
Please Note: To perform this test you must use a spare 560 Ω Pull-
Up Resistor, SPI No:121-5047-00
Disconnect the OPTO Transmitter/Receiver Board from the circuit.
Connect one side of a 560 Ω Pull-Up Resistor to Pin-1 of the OPTO
Receiver Bd. and the other side of the resistor to a 5v DC source.
Connect Pin-2 to GND. Connect a +5v DC source to Pin-1 of the
Transmitter & GND to Pin-2. Align with the Receiver OPTO ap-
proximately 3" distance. Using you Volt-Meter or an Oscilloscope,
monitor Pin-1 while BLOCKING and UNBLOCKING the BEAM
from the Trans. The output will be approximately +5v DC when the
BEAM IS NOT BLOCKED and approximately 0v when the BEAM IS
BLOCKED.
TROUGH DUAL OPTO BOARDS ALIGNMENT/TEST FOR LED1
When a working OPTO is installed and connected in a game, the transmitter should light (LED1 lower & LED2 upper) when the
power is switched on. With the playfield in Service Position #1 (playfield lifted up in the half-way position resting on the prop rod
or edge slide support brackets) and the game on, the LED lights should show up as BRIGHT RED RINGS through the back of the
Reciever Board around the Recievers LED1 & LED2 (see Fig.1). Testing only LED1: With the game in Switch Test Mode, lifting the
Trough Plunger with a fingertip should block the BEAM and cause the Switch Position to trigger (see Fig. 2). View Fig. 2a & 2b (on
the next page) for a sectional view of the Light Path (note alignment) and what happens as a ball breaks the light beam.
A. OPEN OPTO (Light Falling on LED) = SWITCH OPEN. Place Scope lead at Pin-1
of OPTO Rec. Board with Scope Grounded (see schematic). The Scope should dis-
play a steady +5v as shown in Fig. A, Wave Form Diagram.
B. CLOSED OPTO (Ligth Blocked) = SWITCH CLOSED. Place Scope lead at Pin-1
of OPTO Rec. Board with Scope Grounded (see schematic). The scope should dis-
play a Pulse Stream indicating Q2 has switched "On" as shown in Fig. B, Wave Form
Diagram. This is your switch drive pulse.
AC/DC LUCI MANUAL 500-55C8-01
SCHEMATICS, WIRING & PCBS
71