Suggested Repair Parts
This Brasch Gas Transmitter contains few field serviceable parts. However, the fuses are
replaceable in the field. While an open fuse may indicate problems with the circuitry, fuses
may also open because of power surges or ventilation component failure. Therefore, Brasch
recommends that the following fuses be available for replacement.
Qty
Description
Location
Part
Number
1
Fuse, TR5, time-lag, 0.250 A, 250 VAC
Sensor Board Negative Fuse TR5-0.250
1
Fuse, TR5, time-lag, 1.0 A, 250 VAC
Sensor Board Positive Fuse
TR5-1.0
A package containing the proper quantities of fuses can be purchased through your Brasch
distributor.
Troubleshooting
Fault
The yellow LED on the front panel will glow to indicate a fault condition with the sensor. This is
activated upon the sensor reaching the expected end of its useful lifetime. This will be
approximately 10 years from the original manufacturing date for both Carbon Monoxide and
Nitrogen Dioxide sensors.
The signal is triggered by a clock in the sensor board. In the event that the unit loses power, a
supercapacitor will maintain the clock for up to three weeks. While this fault is being displayed,
the area covered by the transmitter will be unmonitored. A signal of 0 mA or 0 V will be sent to
the controller depending on the output settings.
When this error appears, replace the sensor board.
Checking and Replacing Fuses
The circuitry of all the transmitters are protected by time-lag TR5 fuses. They are UL rated at
250 VAC, and manufactured by Littelfuse, series 374.
There are two TR5 time-lag fuses protecting the input circuitry of the sensor board. The fuse
located at FH1 is rated at 1.0 Amp while the fuse located at FH2 is rated at 0.250 Amps. Test
each fuse for resistance and replace if the reading is not near 0 Ω. Always replace fuses with
one having the same rating and characteristics.
IOM02
Rev 1.0 – December 22, 2020
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