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Old February 20th, 2010, 09:33 AM   #1
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a blood-chilling experience...

Due to being tired and short-sighted in the semi-dark room (with the right glasses out of reach at the moment), I've done the most stupid mistake today: I forced my nano's power cable the wrong way into the D-tap socket on the Coco-EX battery adapter (it's unbelievably easy to do it - take it as a warning!)

Of course, my nano didn't power up; horrified, I corrected the D-tap plug (with the nano still unresponsive), and tried to turn on the camera (also powered from the same battery) - this didn't wake up either! So I replaced the BP-U60 battery with another one - and what a relief! Both the nanoFlash and camera work OK...

The Sony's BP battery proved to be smart enough and fuse out first, before any damage was done to the nanoFlash.

Dear Dan, please comfort my mind before the weekend and assure me nothing really happened to the nanoFlash (even if the polarity was wrong for the split second, before the battery self-disabled). Am I right hoping that if the nanoFlash is still operational, no harm was done? I assume there is some protection in it, which would prevent anything more serious happening should the reversed polarity be active for a longer time...
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Last edited by Piotr Wozniacki; February 21st, 2010 at 06:25 AM.
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Old February 20th, 2010, 10:31 AM   #2
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Reverse Polarity Protection

From what I have read there is some reverse polarity protection on the DC input on the nanoFLASH. Presumably if you left it powered up too long it would fry that diode (if that is how they protect the circuit) and then the unit would not power up when given the right polarity and voltage since that diode is now "open".
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Old February 20th, 2010, 12:16 PM   #3
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That's if it just used one diode. If it used two or more, the reversed current would be completely blocked for no harm. Of course, that protective configuration is less efficient due to the voltage drop across the diodes. And since the battery did clear the fuse, some current would have spiked somewhere in a circuit. If it's working now, I wouldn't lose any sleep until it doesn't, but that's me. I doubt a single diode across the dc rail would be shorted by one brief instance of a current spike. They are commonly applied just for that purpose, to dissipate brief spikes due to static electricity and other interference phenomenons.
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Old February 20th, 2010, 01:01 PM   #4
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Thanks guys. Anyway, Bebob should revise the design of their Coco-EX adapter's D-tap socket - it is far too easy to plug into it the wrong way! I didn't use force at all...
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Old February 20th, 2010, 01:02 PM   #5
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Dear Friends,

We designed the nanoFlash to the best of our ability to handle accidental applications of revesre polarity.

We do ask that the reverse polarity be of short durations, do not leave it connected if it does not power up.

Also we designed some over-voltage protection, but not much.

Our input voltage range is 6.5 to 19.5 Volts DC (actual voltage, not battery nonimal voltage ratings).

We know for a fact that 28V DC is too much voltage for a nanoFlash.
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Old February 20th, 2010, 01:11 PM   #6
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Quote:
Originally Posted by Dan Keaton View Post
We do ask that the reverse polarity be of short durations, do not leave it connected if it does not power up.
Dear Dan - thanks to the battery's own protection, the reversed polarity voltage was present for just a split second. I'm more concerned about the surge that might occur - but if my nano is working fine, are you saying there's nothing to worry about?
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Old February 20th, 2010, 01:13 PM   #7
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Dear Piotr,

There is nothing to worry about, our reverse polarity protection works.
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Old February 20th, 2010, 01:21 PM   #8
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Thanks again, Dan.

I'm now feeling lucky this happened to me during some tests of the new firmware, and not at some important shoot.

Have a nice weekend :)
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Old February 20th, 2010, 03:36 PM   #9
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Quote:
Originally Posted by Tom Roper View Post
That's if it just used one diode. If it used two or more, the reversed current would be completely blocked for no harm. Of course, that protective configuration is less efficient due to the voltage drop across the diodes. And since the battery did clear the fuse, some current would have spiked somewhere in a circuit. If it's working now, I wouldn't lose any sleep until it doesn't, but that's me. I doubt a single diode across the dc rail would be shorted by one brief instance of a current spike. They are commonly applied just for that purpose, to dissipate brief spikes due to static electricity and other interference phenomenons.
The power input to the nanoFlash has a resettable poly fuse followed by a 20V Zener diode, connected to ground. If you reverse the polarity then the Zener diode will start to conduct with about a 0.5V forward voltage. This should cause the fuse to open, until the fault is removed. If the input voltage is above 21V, then the diode will zener and the fuse should once again open.

If you leave the power supply connected for a long period of time, I have seen the diode short-out completely (I think the fuse may try to reconnect). This should protect the nanoFlash power supply circuitry, but the diode will have to be replaced to allow the unit to operate (a relatively low-cost repair).

Piotr - I think your nanoFlash is fine, as Li-Ion batteries have over-current protection, so the fault only occurred for a very brief period of time.

Best-
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Old February 20th, 2010, 04:47 PM   #10
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Originally Posted by Mike Schell View Post
Piotr - I think your nanoFlash is fine, as Li-Ion batteries have over-current protection, so the fault only occurred for a very brief period of time.

Best-
I hope so too, Mike. I remember some time ago (before the nanoFlash), I tried powering a 20W lamp from the same Bebob Coco-EX's D-tap socket while feeding the camera at the same time. The load proved to be too much, and the battery shut off the moment I switched the lamp on - just like today with the nano. I didn't even notice any light actually, so the BP-U60's protection circuitry must have been really fast.

I have used the lamp successfully after fitting it with the "soft start" device.

BTW, it's enough to put a disabled BP-U60 battery on the Sony charger, and it gets revived within a couple of seconds.
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Old February 20th, 2010, 05:00 PM   #11
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We know for a fact....

"We know for a fact that 28V DC is too much voltage for a nanoFlash."

I would love to hear that story someday......
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Old February 20th, 2010, 05:18 PM   #12
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Piotr,

Welcome to the world of Anton Bauer (laughing). Anyone who has worked with P-taps (D-taps) has had these near-death experiences.

Some of the housings on the female receptacles are prone towards spreading out. This allows you to plug in the P-Tap the wrong way around.

If you get one of these...

http://www.bhphotovideo.com/bnh/cont...=204182&is=REG

...make sure you apply velcro on the sides of the 4 receptacle bit to keep the unit together.

I actually give myself more setup time and carry a spare set of glasses in my camera bag and an extra led light just so I won't do exactly what you did.

I often have 4 or more items on my camera/steadicam rig that require power. Some use LEMO connectors and the rest are Anton Bauer P-taps.

They have become a standard not only due to the prevalence of A/B batteries but also you can make P-Tap cables fairly easily in the field or on a set (assuming you have a soldiering iron handy) and they are a lot cheaper than HIROSE and LEMO connectors that are much better but more expensive and finicky to make.
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Old February 20th, 2010, 05:27 PM   #13
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Quote:
Originally Posted by Andrew Stone View Post
Some of the housings on the female receptacles are prone towards spreading out. This allows you to plug in the P-Tap the wrong way around.
Exactly Andrew - lesson taken :)
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Old February 20th, 2010, 05:58 PM   #14
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This is troubling. Both the inner and outer part of the female connector is meant to be polarized making it impossible to ram the plug in the wrong way around. It looks like corners are being cut. We've also found some of the cheap plugs make intermittent connect. This is a bit of pain when it makes your on camera light blink and a serious issue when a recorder looses power.
I've also noticed that the genuine AB parts are bakelite which has no flex. The Chinese cheapies seem made of a flexible plastic which also makes it easier to get something plugged in the wrong way around. Perhaps painting one side of the plug and socket white would help avoid the problem when working under stress in the dark.
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Old February 20th, 2010, 06:38 PM   #15
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Dear Bob,

All of the P-Tap (D-Tap) cables that we make use genuine Anton Bauer male P-Tap plugs.
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