Falcon NVRAM not retaining settings with power removed

[dml]

I have been noticing a weird issue with a F030 machine that I have been unable to explain. In fact I'm sure I have seen this issue in more than one machine but passed it off as battery or corrupt NV state related until now. This time I'm looking at it more closely.

Symptoms:

- NVRAM unit replaced with a turned-pin socket. clean job, no damaged vias/pads or anything like that.
- NVRAM replaced with alternative (was supplied with Centurion version - unused - but tried the Exxos version also with similar result)
- NVRAM state initially corrupted so a few of the config tools e.g. BOOTCONF.APP just don't work correctly to begin with but the NVCONFIG.CPX does report corrupted state and does let me reset it.
- configure the NV state with NVCONFIG.CPX (UK / 24hr / VGA 80column, non-st-compat), with the 80column mode being an easy way to notice if the state has been preserved at boot time because it will usually fall back to ST Low when it screws up!
- reset button (or warm reset) shows the settings have 'taken' and it boots in 80column from this point onwards.
- power off for a few seconds, still booting in 80column
- power off for a couple of minutes, still booting in 80column
- power off, short the 5V rail on the mainboard for a few minutes, still booting in 80column
- power off and leave OVERNIGHT
- boots in ST low (!!!!!) NV ram state is corrupted according to NVCONFIG.CPX

I can repeat this multiple times, always the same result. The RTC will not retain settings for long with power removed.

Have checked the battery and it is sitting at 3.2v. I can also see 3.2v present on one of the onboard IC pins with the unit in or out of its socket.

Clearly the IC is accepting the settings and is retaining them across a reset so it's not a programming issue. It is acting as if the onboard battery is doing nothing, or is below working voltage. I could maybe put that down to a faulty RTC unit if it was just one unit but I saw this with 2 so far.

I'm also pretty sure 3.2v is correct and should be working.

Getting tempted to drill out an old DALLAS IC and hook up an external battery to see if anything different happens (?)

Any ideas/suggestions welcome :shrug:

[exxos]

There was a issue I found some time ago about such things.. I designed and built a new RTC which should fix that issue.. Your welcome to try one.. Just not sure where I put them.. Probably waffled about it somewhere..

[dml]

There was a issue I found some time ago about such things.. I designed and built a new RTC which should fix that issue.. Your welcome to try one.. Just not sure where I put them.. Probably waffled about it somewhere..

Thanks - so maybe its a compatibility thing? I'm trying an experiment just now with the original RTC repaired (took the top off, extracted the crystal and attached a new battery). If I get the same result I suppose it will point at the machine in some way. That would be a weird result though...

[exxos]

Thanks - so maybe its a compatibility thing? I'm trying an experiment just now with the original RTC repaired (took the top off, extracted the crystal and attached a new battery). If I get the same result I suppose it will point at the machine in some way. That would be a weird result though...

I'd imagine you won't have issues putting a new battery in. Its hard to explain but its like "hardware bugs". I think ieven discussed it with maxim technical at the time to confirm my theory. RTC circuit was updated but I could not reproduce the failure on my falcon. So had no way to confirm if the fixes would work or not.

[exxos]

Found one thread

viewtopic.php?t=7624