🚀 go-pugleaf

>In article <1992Oct8.025357.9551@cube.handheld.com> jmd@cube.handheld.com (Jim De Arras) writes:
>>In article <1ask66INN2ga@ustores.ustores.missouri.edu>
>
>I would NEVER put the battery in backwards!  If they have a protection diode,
>it will do nothing.  If not, you run the risk of damaging the clock chip, or of
>exploding caps or even (remotely) blowing the battery seals!

    If the battery is connected directly to the RTC chip then you are
    definitely forward biasing the static discharge diodes internal to the
    device, about 50 ohms per pin (in parallel) if you reverse the battery.
    This would destroy the RTC chip rather quickly.

    if there is a protection diode across the batterly leads (and not
    inline) to protect the RTC chip, the battery will be shorted and can,
    literally, explode.

    On the otherhand, if NeXT has inserted a diode in series with the
    battery, then nothing will happen at all because the diode will be
    reverse biased.

    I don't know what RTC chip the NeXT is using.  Most RTC chips, like the
    ones from Dallas Semiconductor, draw picoamps (on the order of 300pA or
    less).  Therefore, the bypass capacitors alone would be able to retain
    enough voltage to run the RTC for several minutes.	The best solution
    is to take out the battery and short the battery terminals on the
    motherboard together for a second or two to discharge the bypass
    capacitors.

    NOTE:  I HAVE NOT TRIED THIS MYSELF but it's certainly safer then
    putting the battery in backwards!

					-Matt

>> --
>> Bill Canning 		usbill@ustores.ustores.missouri.edu (Internet)
>> (314) 882-2131			muccgw.usbill@ssgate.missouri.edu
>(cc:Mail)
>> [314] 882=4699 (Fax) 	CSPECWC@MIZZOU1 (BITNET)
>
>Jim
>
>--
>Jim De Arras		 | The opinions expressed herein are
>Hand Held Products, Inc.| not necessarily those of Hand
>804.784.3090 voice	 | Held Products, Inc., and may not
>804.784.3147 FAX	 | even be mine. Use at your own risk

--

    Matthew Dillon		dillon@Overload.Berkeley.CA.US
    1005 Apollo Way		uunet.uu.net!overload!dillon
    Incline Village, NV. 89451	ham: KC6LVW (no mail drop)
    USA 			Sandel-Avery Engineering (702)831-8000