Smart card reader/door controller frozen or defaulted after "Brownout"
Certain products, including TS0870x-series Smart Card Readers and TS0862 Smart Door Controllers, may fail to recover from a partial loss of supply voltage in a rare combination of circumstances.
This condition may occur when the system has been running on batteries, the batteries are almost fully-depleted (the supply voltage falls to approximately 2 V), and the power supply does not have an under-voltage cut out.
Devices that do not have an under-voltage cut out include:
• TS0073 2A 12 VDC Power Supply
• TS0820 or TS0824 Standard DGPs (AC or DC versions)
• TS0810 Access Manager
• TS0868 High-Level Lift Protocol Controller
• TS0867 Intelligent 4-Door Controller manufactured prior to 2002*
• TS0869 Intelligent 4-Lift Controller manufactured prior to 2002*
• TS0816 Challenger panels manufactured prior to 2002
• any other (third-party) 12 VDC power supply that does not have an under-voltage cut out
* Ensure that current does not exceed 2 A when using TS0843 relay modules.
If a rare combination of circumstances results in a device that fails to respond after power has been restored to the system (e.g. a reader does not respond to a card), you must completely power down the reader and then repower it.
A TS0843 relay module may be used as an under-voltage cut out and can be wired into the affected device’s power supply (maximum current 2 A) with a zener diode. Refer to the diagram below for connections and relay link settings. Use an 8.2 V 1 Watt zener diode, such as a Jaycar ZR1408 8.2V 1N4738 1 Watt Zener Diode, not supplied with TS0843.
The cut out voltage is 11 V ±0.2. TS0843 is sold as a strip of 4 snap-off relay modules.
Taken From FNN MANOTE-TS0843 • ISS 24AUG09 1