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 any resolution to the auto-on feature not working on fit-pc 
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Joined: Sun Apr 29, 2012 11:54 am
Posts: 3
Post any resolution to the auto-on feature not working on fit-pc
There are many posts about the auto-on feature not working correctly on the fit-pc. I have the same issues that are described in many of the previous posts dating back to 2009. I started purchasing fit-pc's in q4 of 2010 and I am having the same issue where the auto-on feature worked fine, and now the auto-on feature is not working. i deploy the fit-pcs as a hardened appliance inside of hospitals within a custom enclosure with no access to the fit-pc. like many applications when there is a power cycle it is critical that the fit-pc power turns on and the unit boots normally. when the auto-on feature is not working, we lose remote access to the unit and have to dispatch a human to the hospital to open up the case and press the button. has there been a definitive root cause analysis for this problem? please post a reply.
thanks,
pmoj


Wed Sep 25, 2013 2:43 pm
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Joined: Mon Mar 16, 2009 2:11 pm
Posts: 2334
Post Re: any resolution to the auto-on feature not working on fit
The auto-on circuit is implemented since 2010 in fit-PC2 and since day 1 in fit-PC2i, therefore it is important to distinguish between issues from 2009 and later reports.
There has been several cases of auto-on failure in the field, but considering that there are hundreds of thousands fit-PC2/i in the field, many of them in industrial scenarios that require auto-on, the problem is not common.
It is worth explaining our procedures with respect to auto-on:
Each fit-PC2 is tested for auto-on functionality before being shipped.
When we receive a report about auto-on failure we ask the unit to be sent by RMA and try to reproduce the problem. In most cases the problem cannot be observed in a hundred switching cycles. Nevertheless we replace the components of the auto-on circuit and check it again for functionality.
Our analysis indicates there is no single root-cause, but there are several factors involved:
- Operation - capacitors in auto-on circuit should be allowed to discharge before power is resumed. We recommend 10 seconds or more before power is restored. In short power dips fit-PC2 might not wake up. Note that PSU has capacitors as well so it takes a few seconds for fit-PC2 to see 0V in the DC input.
- DC transient - when feeding fit-PC2 from a custom DC source transient may be different than that of the standard PSU. This may affect the auto-on behavior.
- Component failure - while fit-PC2 is built using embedded grade components, occasionally a component may deteriorate or fail. Sometimes a slight change in the capacitance of a capacitor in the RC element of the auto-on circuit may lead to marginal behavior.

Recommendations:
- Each fit-PC2 that manifests unreliable auto-on is entitled RMA.
- Before deploying an unattended system stress test auto-on. This would uncover marginalities with system power design.
- Auto-on issues when arise tend to be marginal so they manifest infrequently. e.g. one in ten power cycles auto-on fails. If the system is designed to allow power recycling it is most likely to wake up on the first recycle after failure. It still needs to be fixed, but the emergency is lessened.

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Irad Stavi
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Sun Sep 29, 2013 8:30 am
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