Wireless SIM board faults

General troubleshooting

This topic is mostly here as a pointer to comments that are described in more detail under other troubleshooting topics. The ISS SIM board is obviously the commonest type of SIM board, but the principles below apply to all types of wireless transmitter boards. Wireless SIM board issues usually fall into one of two categories:

  • Loss of readings from all sensors connected to that transmitter;
  • Recurring low battery warnings;

If readings from only a single sensor look incorrect then the fault is almost certainly with the sensor rather than the SIM board and so troubleshooting comments for that particular sensor need reviewing. Be aware, however, that some readings simply fail to update (ie the last reading received persists on the display) rather than reading zero or dashed out. So a careful check that all readings are updating as expected is required to be sure of the nature of any potential issue.

If all sensor readings from a given transmitter are missing or not updating then this could be caused by a weak or missing signal (in which case see the Wireless troubleshooting topic) or, sometimes, by a supercap fault.

The Low battery warning topic is obviously the place to look for advice on dealing with station low battery warnings and supercap faults are again one possible cause of issues.

VP2 SIM boards

In general, most issues encountered with wireless SIM boards are covered by the troubleshooting topics referenced above. The only hardware repairs that can readily be made to a SIM board are replacing the supercap or cleaning the battery contacts. If these repairs aren’t relevant then the only other option is usually to replace the board with a new one – no other component-level repairs are usually practicable.

There are a couple of other minor board-related issues that it’s relevant to include here:

Water ingress

Rain/moisture penetration on to the SIM circuit board can occasionally be a problem. This is usually caused by the front cover not being replaced squarely (or not fully latched home) or the foam plug in the rear access port is missing or has seriously deteriorated with age. Identifying and fixing the source of moisture will usually cure the problem.

The SIM board is actually well-protected against moisture with a conformal coating, but water droplets can cause erroneous readings if they reach the inside of the sensor sockets and start shorting across two or more of the contacts inside the socket. Symptoms will obviously depend on which socket is affected but, for example, moisture in the wind sensor socket can cause persistent and spuriously high wind speed readings or very high rainfall readings if in the rain socket. If this issue is suspected then unplug the relevant plug and look carefully for any small water droplets, which can be dabbed dry with a tissue and the plug left out for a few hours to allow complete drying out. The source of the water ingress obviously needs to be identified and remedied as well. (NB The gold contacts inside each socket are protected during manufacturing with a waxy water-repellent material – this is deliberate and not dirt or corrosion as is often mistakenly thought, but moisture ingress can sometimes be enough to overcome this protection.)

Sensor cable sockets

Moisture in the sensor sockets is covered above, but the plug/socket connection can, very occasionally, give trouble in other ways. If data
from a single sensor only, eg wind or rain, is giving problems then it’s always worth double-checking the plug/socket connection. Occasionally the plug may not have clicked fully home or a piece of grit or dirt may have lodged between a pair of contacts, so just unplug the cable, check visually and replug, ensuring that the plug positively clicks home. (But note that the anti-moisture coating within the socket is not dirt but there by design and should not interfere with good contact being made.) If a sensor fault persists and cannot be traced to a fault in the sensor itself or the cable then check also that the plug is correctly crimped on to the cable. Bend the cable back firmly (but without using excessive force) where it enters the plug and check in good light that none of the individual conductors seems loose. If any defect is seen then the plug will need to be recrimped on to the cable.

ISS solar panel discoloration

On wireless VP2 stations, the solar panel on the sliding white SIM compartment cover can deteriorate cosmetically with age. This is rarely a major problem in that even a badly discoloured panel still seems to work adequately, though battery life may be somewhat reduced. We have heard of people being able to clean up the outer surface of the panel (which is where the problem arises) using a standard liquid mildly-abrasive household cleaner. Alternatively, new panels can be purchased as part 7345.114.

Vue stations

The general principles of troubleshooting for low battery warnings or lost wireless signal for Vue stations are exactly as described in the General Troubleshooting section above.

However, the physical SIM design and access of Vue stations are obviously quite different to VP2 models. Also, the Vue ISS hardware has been through multiple revisions over recent years and it is important when thinking of ordering spares to know exactly which Vue revision you have. If there is a persistent SIM or sensor issue on a Vue and the unit is out of warranty then the simplest solution is often to buy a complete new ISS unit – the price will often not be much more than buying the relevant spares. See the Vue ISS topic for further discussion and advice on this point.

Cabled SIM board faults

It is very rare for cabled SIM boards to give problems – these boards are relatively simple and do not have either a battery or the supercap component that is a common cause of recurrent low battery warnings on the wireless models. And provided the cable from ISS to console has not been damaged (which is obviously something to investigate if data is lost from a cabled VP2) then none of the data loss issues will be seen that are possible with the wireless models.

There is, however, a rare issue where a cabled SIM board can appear to lock up and stop sending data. Troubleshooting this issue is described in the ‘Outside data missing’ topic in the consoles section.


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