Communications, General Troubleshooting; Temperature Problems; Box / Chassis Temperature; Photometer Sample Chamber Temperature - Teledyne T750 User Manual

In some rare circumstances, this failure may be caused by a bad IC on the motherboard,
specifically U57, the large, 44 pin device on the lower right hand side of the board. If this
is true, removing U57 from its socket will allow the instrument to start up but the
measurements will be invalid.
If the instrument stops during initialization (triggering an Alert), it is likely that the DOM,
the firmware or the configuration and data files have been corrupted.
RS-232 C
Teledyne API calibrators use the RS-232 communications protocol to allow the instrument
to be connected to a variety of computer-based equipment. RS-232 has been used for many
years and as equipment has become more advanced, connections between various types of
hardware have become increasingly difficult. Generally, every manufacturer observes the
signal and timing requirements of the protocol very carefully.
Problems with RS-232 connections usually center around four general areas:
•
•
•
•
T
EMPERATURE
Individual control loops are used to maintain the set point of the UV lamp and ozone
generator. If any of these temperatures are out of range or are poorly controlled, the
calibrator will perform poorly.

Box / Chassis Temperature

The box temperature sensor is mounted to the motherboard and cannot be disconnected to
check its resistance. Rather check the BOX TEMP signal in the Dashboard. This parameter
will vary with ambient temperature, but at ~30
should be ~1450 mV.

Photometer Sample Chamber Temperature

The temperature of the gas in the photometer sample chamber should read approximately
5.0°C higher than the box temperature.

UV Lamp Temperature

There are three possible causes for the UV Lamp temperature to have failed.
The UV Lamp heater has failed. Check the resistance between pins 5 and 6 on
•
the six-pin connector adjacent to the UV Lamp on the Optical Bench.
•
148
, G
OMMUNICATIONS ENERAL
Incorrect cabling and connectors (see RS-232 Com Port Connector Pin-outs
in Section 2.4.1.6).
The BAUD rate and protocol are incorrectly configured (see RS-232 Com
Port Default Settings in Section 2.4.1.6).
Incorrect setting of the DTE – DCE Switch (see Section 5.1.1).
Verify that the cable that connects the serial COM ports of the CPU to J12 of
the motherboard is properly seated
P
ROBLEMS
It should be approximately 30 Ohms.
T
ROUBLESHOOTING
o C (6-7° above room temperature) the signal
083730750B DCN8606