KeyPad
Version 1.0
SCP SCIENCE
29
Digi
SET
operation and service manual).
Opto-isolated Triac Driven circuit verifi cation
Fan verifi cation
• The fan should turn on at power-up. If it does
not or if it does slowly, replace the fan and
the triac. In both cases, it will cause the triac
to be overheated and destroyed.
• To remove the fan, unscrew the 2 screws as
shown in fi gure 17.
IGURE 17: FAN SCREWS LOCATION
Legend
1. Fan screws
Opto-isolator section verifi cation
This test will confi rm if the CPU is
operating
correctly.
• Remove the bottom plate
• Set the target temperature to 35
o
C and
target time to 1 minute.
• After starting the system, turn the module
upside down and see if the LED D9 (see
fi gure 18 for position) is fl ashing.
Be very careful not to touch any
components inside the KeyPad as it
is
running.
The block temperature must be
lower than the set point temperature
for the LED to fl ash.
• If the LED is not on, if possible, use and
oscilloscope and verify if there is a
pulsing signal on the trigger input
(TP8), coming from the CPU. If there
is no signal on TP8, please refer to the
CPU section for more details.
Otherwise, check the integrity of the LED
and the transistor Q2 (see below).
• If there is a signal on TP8, the block
temperature is below set point temperature,
the
Digi
SET
dongle and cable are
installed correctly and the LED is ON
or fl ashing, measure the voltage at TP9. It
should be maximum 3Vdc. If it is higher or
close to 0Vdc, change the opto-coupler
U8.
FIGURE 18: OPTO-ISOLATOR U8, TEST POINTS AND LED D9
Legend
1. Test Point TP8
2. D9 SMT LED (green)
3. Test point TP9
4. U8
NOTE
NOTE
Содержание DigiPREP
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