Teledyne 360E Carbon Monoxide Alarm User Manual


 
TROUBLESHOOTING & REPAIR PROCEDURES Model 360E Instruction Manual
A voltmeter should b
e used to verify that the DC voltages are correct per the values in the table below, and an
oscilloscope, in AC mode, with band limiting turned on, can be used to evaluate if the supplies are producing
excessive noise (> 100 mV p-p).
Table 11-7: DC Power Supply Acceptable Levels
CHECK RELAY BOARD TEST POINTS
FROM TEST POINT TO TEST POINT
POWER
SUPPLY
ASSY
VOLTAG
E
NAME # NAME #
MIN V MAX V
PS1 +5 Dgnd 1 +5 2 4.8 5.25
PS1 +15 Agnd 3 +15 4 13.5 16V
PS1 -15 Agnd 3 -15V 5 -14V -16V
PS1 Agnd Agnd 3 Dgnd 1 -0.05 0.05
PS1 Chassis Dgnd 1 Chassis N/A -0.05 0.05
PS2 +12 +12V Ret 6 +12V 7 11.75 12.5
PS2 Dgnd +12V Ret 6 Dgnd 1 -0.05 0.05
11.5.3. I
2
C Bus
Operation of the I
2
C buss can be verified by observing the behavior of D1 on the Relay Board in conjunction with
the performance of the front panel display. Assuming that the DC power supplies are operating properly and the
wiring from the motherboard to the Keyboard, and the wiring from the keyboard to the Relay board, is intact, the
I
2
C buss is operating properly if:
D1 on the relay board is flashing, or;
D1 is not flashing but pressing a key on the front panel results in a change to the display.
11.5.4. Keyboard/Display Interface
The front panel keyboard, display and Keyboard Display Interface PCA (03975 or 04258) can be verified by
observing the operation of the display when power is applied to the instrument and when a key is pressed on the
front panel. Assuming that there are no wiring problems and that the DC power supplies are operating properly:
1. The vacuum fluorescent display is good if on power-up a “-“ character is visible on the upper left hand
corner of the display.
2. The CPU Status LED, DS5, is flashing, See Section 11.1.4.1.
3. If there is a “-“ character on the display at power-up and D1 on the relay board is flashing then the
keyboard/display interface PCA is bad.
4. If the analyzer starts operation with a normal display but pressing a key on the front panel does not
change the display, then there are three possible problems:
One or more of the keys is bad,
The interrupt signal between the Keyboard Display interface and the motherboard is broken, or
The Keyboard Display Interface PCA is bad.
210 05232 Rev B3