Raymarine ST60 Depth offset reset

[Sea Seven]

The depth offset on my Raymarine ST60 Depth seems to have reset itself to zero. It was previously set with a negative offset to show depth below the keel. The previous week my domestic batteries were expiring and the voltage dropped to around 9v. At that voltage the chart-plotter was beeping and the wind instruments were showing incorrect readings.
I had some new domestic batteries fitted a few days after.
It was worrying to find that the offset had been zeroed and I wonder if there is an explanation for this. I can't think how else it could have happened. Does it relate to the voltage drop?
I've now changed my policy to show depth from the water level because it has a lower risk consequence if it zeros again.

 

[FulmarJeddo]

There has been discussion on here about ST50 and a few ST60 wind instruments losing their calibration on power down. It could be a similar issue. there must be some sort of power storage device, either a battery or capacitor that retains the memory, that deteriates with age. I would be surprised if running on a low voltage would affect the setting. I may be wrong though.

 

[nigelmercier]

One of the reasons I have mine showing depth of water.

There is no battery. The settings are stored in a memory chip. Low voltage could trigger a reset, but more likely it was finger trouble

 

[Hydrozoan]

There has been discussion on here about ST50 and a few ST60 wind instruments losing their calibration on power down. It could be a similar issue. there must be some sort of power storage device, either a battery or capacitor that retains the memory, that deteriates with age. I would be surprised if running on a low voltage would affect the setting. I may be wrong though.

Yes - regarding ST50s, for example, see:

http://www.ybw.com/forums/showthrea...T50-Plus-log-not-retaining-calibration-factor

and

http://www.ybw.com/forums/showthread.php?449795-Autohelm-ST50-Plus-Fault-Finding-Internal-Battery

though it still does not seem to be absolutely clear if there is a power storage device, and/or if memory has been at fault. I have seen reports on the wider web of voltage spikes (up as well as down) causing problems, too.

 

[earlybird]

it still does not seem to be absolutely clear if there is a power storage device, and/or if memory has been at fault. I have seen reports on the wider web of voltage spikes (up as well as down) causing problems, too.

I'm fairly certain that there is no battery or similar. I once had settings in a Stowe Dataline system altered due to a faulty on/off switch putting spikes on the power line, and upsetting the EPROMs or whatever.
Perhaps also a possibility with Raymarine kit.

 

[Hydrozoan]

I'm fairly certain that there is no battery or similar. I once had settings in a Stowe Dataline system altered due to a faulty on/off switch putting spikes on the power line, and upsetting the EPROMs or whatever.
Perhaps also a possibility with Raymarine kit.

Thanks. Yes - and as indeed Nigel avers above (I had not seen his post - slow fingers!) and as you suggested in one of the threads I linked, though there were contrary opinions too: http://www.ybw.com/forums/showthread.php?449795-Autohelm-ST50-Plus-Fault-Finding-Internal-Battery

I shall henceforth assume there is no battery (in any of the 50/60 heads, I presume?). It did seem from my wider search that low (or high) voltage could cause problems, and finger trouble is never to be dismissed. My ST50 and ST60 heads have done well - the former with just display element replacement abut a decade ago - so I could hardly complain if they gave up the ghost tomorrow.