It is also important to remove the power cable from the radio and not just turn off the power supply

Geoff AB6BT

In the document "How to Reset the Persistence Database for a FLEX-6000" There is this statement:

"Remove the power cable from the radio for at least 30 seconds and then reconnect it.  It is also important to remove the power cable from the radio and not just turn off the power supply."

Can someone explain why this is necessary? I would think that turning off the power supply and waiting for the output voltage to decay to 0 Volts would be sufficient.

Bill -VA3WTB

A power supply may drain down to 0 volts, but there may be millivolts still present.

Geoff AB6BT

OK, but I'm not aware of any semiconductor device that can be forward biased by a few millivolts, perhaps a few hundred millivolts for sure.

0 volts is 0 volts...

I'm just trying to understand the reasoning here.

Bill -VA3WTB

It may have more to do with letting the radio drain properly instead of the PS. It would be interesting if Tim could explain this out of interest.

Geoff AB6BT

Agreed!

Jim KJ7S

It has been shown, sometimes, that when or as the voltage drops when shutting off the PS without pulling the power cable, corrupts the radio's firmware, causing an improper restart. Creating all manor of difficulty in the reset/reboot of the radio.

Tim - W4TME

The FLEX-6000 is not like most radios.  There are at least 6 independent processors that are working in concert with one another.  One of the processors is the PSoC, which is responsible for handling different hardware systems, such as temperature and voltage monitoring and when you press the power button, it recognizes a button has been pressed and then uses logic to initialize the other processors in the radio.  These are just a few things the PSoC does.

Whenever there is DC power applied to the radio, the PSoC is active.  Removing the DC power cable ensures it is shut down and the time period is needed to ensure all of the internal sensors are reset.  Simply turning off the power supply may not ensure that this low-level reset completes successfully since there is a voltage bleed down once you turn off the power supply.  Since we do not know how long the bleed down will take, removing the DC power and waiting for the 30 seconds will ensure the PSoC is completely reset before restarting the radio.

Tim - W4TME

I am afraid this simply is not a true statement.

Geoff AB6BT

Thanks Tim.

I do understand the reasoning behind your explanation. I guess the last sentence is the key to why you recommend this procedure. As you say you have no way of determining how long it will take for any given power supply to reduce its output voltage to below some threshold sufficient to guarantee a reset of the PSoC and removing power will assure that.

On the other hand there must be a specific voltage below which the PSoC will reset. So if the power supply voltage is  below the reset threshold then the reset will occur. If I were to monitor that voltage and wait until if dropped low enough wouldn't that accomplish the same thing?

Tim - W4TME

You're welcome.  In addition to the processor needing to be powered down for the reset to occur, there are sensors and controllers connected to the PSoC that need to reset too and some of them require zero voltage for 30 seconds.  If you do not want to remove the DC power cable, then wait 30 seconds after the voltage decay has hit 0V.  

Geoff AB6BT

I appreciate you taking time to elaborate.

Thanks and stay safe.

AC9S

Thanks Tim,  Physically removing or interrupting the PS cable is difficult at my station.  I'll wait more than 30 seconds after the decay to 0.

Keith - AC9S

Tim - W4TME

RRR.  Understood.  73.