SEISMO Technical Bulletin
Some v3 SEISMO vibration / tilt sensors made between March 2022 and March 2023 can show an incorrect zone resistance at the control panel (CIE). The fix is simple and done on site: reverse the two zone connection wires. No return or modification is needed.
2 pages. Includes photos of the v3 labels and PCB, and wiring diagrams of the normal and abnormal connection.
Affected products
Only v3 products within these serial number ranges are affected:
| Product | Serial numbers | Production dates |
|---|---|---|
| SEISMOV3 | 0000000001 – 0000002091 | 01/03/2022 – 19/03/2023 |
| SEISMO-ADVANCEV3 | 0000000001 – 0000002734 | 01/03/2022 – 19/03/2023 |
| SEISMO-ADVANCE-CV3 | 0000000001 – 0000000049 | 01/03/2022 – 19/03/2023 |
| SEISMO-ADVANCE-BKV3 | 0000000001 – 0000000096 | 01/03/2022 – 19/03/2023 |
| SEISMO-ADVANCE-GYV3 | 0000000001 – 0000000004 | 01/03/2022 – 19/03/2023 |
| SEISMO-ADVANCE-B-CV3 | 0000000001 – 0000000032 | 01/03/2022 – 19/03/2023 |
Products made from 20 March 2023 onwards, with serial numbers above these ranges, are not affected.
How to tell if you have a v3 unit
- Label inside the lid: the small product label is marked v3.
- Outer packaging: the larger packaging label is also marked v3.
- The PCB: v3 boards always have a square potentiometer. Older, unaffected versions have a round one.
If a unit is still sealed in its bag with these labels and was bought before 20 March 2023, assume it is covered by this bulletin.
What happens and why
The control panel shows an abnormal status for the zone the sensor is connected to. The cause is a change to the specification of an onboard ESD protection diode, from bidirectional to unidirectional. If the zone connection is wired with the opposite polarity to the diode, the panel sees a different voltage and so a different zone resistance. Both the alarm and fault output relays are protected by these diodes, so the effect adds up when both outputs are used, as in a Grade 3 TEOL installation.
A standard multimeter will not show the fault. It can be seen with an oscilloscope or at the control panel.
Remedy
Reverse the zone connection wires. This restores normal operation in place, with no need to return or modify the product.
Example from the bulletin, a Pyronix TEOL installation (2k2 / 4k7 / 6k8): wired the wrong way round, the panel reads 3k5 instead of 2k2 secure; with the two zone wires swapped, it reads 2k2 secure. The PDF shows both wiring arrangements.
If reversing the wires does not clear the fault at the panel, please contact us for further help.
Issued by
Knight Fire and Security Products Ltd
Unit 84, Seawall Road Industrial Estate, Cardiff, CF24 5TH, United Kingdom
T: +44 (0)29 2048 8129