Teledyne M300EM operation manual 13.5.3.I2C BUS, Keyboard/Display Interface, Table

Teledyne API – Technical Manual - Model 300E Family CO Analyzers Troubleshooting & Repair

A voltmeter should be 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 13-7:		DC Power Supply Acceptable Levels
POWER		CHECK RELAY BOARD TEST POINTS
SUPPLY	VOLTAGE	FROM TEST POINT			TO TEST POINT		MIN V	MAX V
ASSY
		NAME		#	NAME	#
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

13.5.3.I2C BUS

Operation of the I2C bus can be verified by observing the behavior of DS6 and DS7 on the motherboard and 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 I2C bus is operating properly if:

∙DS6 and DS7 on the motherboard are flashing at least once every 2 seconds and 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.

13.5.4.KEYBOARD/DISPLAY INTERFACE

The front panel keyboard, display and Keyboard Display Interface PCA (P/N 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 13.1.4.1.

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.

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