23 Mar
1998
23 Mar
'98
3:57 a.m.
I picked up an original PC/AT that has a dead lithium battery for the
CMOS bios parameter storage. The battery says it's 6.8 volts. It's the
kind that is a 1/2x1x2 inch pack with a six-inch lead.
I've tried several places to find a replacement, but either a store
doesn't have it, or, if they have one, the voltage is not exactly 6.8
volts.
So, what's the acceptable voltage range, especially on the low end? And
any good sources?
Thanks,
Dave
22 Mar
22 Mar
11:21 p.m.
Nice machine. :) All you need is either:
4.5V or 6V external battery and that is either alki or lithium
battery. The actual operating cmos stand by voltage is appox 3v cut
down by series of diodes network.
How big the motherboard? There's 2 types, one is large size and use
36 chips using stacked 128k x 1bit chips, the smaller one (better
one) has 18 chips of 256k x 1bit memory, And bios is clock-protected
if anyone tries to overclock that boards, no boot and can be
unprotected with manual editing to the bios contents and burn pair of
new bios chips.
Jason D.
I picked up an original PC/AT that has a dead lithium
battery for the
CMOS bios parameter storage. The battery says it's 6.8 volts. It's the
kind that is a 1/2x1x2 inch pack with a six-inch lead.
I've tried several places to find a replacement, but either a store
doesn't have it, or, if they have one, the voltage is not exactly 6.8
volts.
So, what's the acceptable voltage range, especially on the low end? And
any good sources?
Thanks,
Dave
email: jpero(a)cgo.wave.ca
Pero, Jason D.
23 Mar
23 Mar
4:35 a.m.
jpero(a)cgo.wave.ca wrote:
Nice machine. :) All you need is either:
4.5V or 6V external battery and that is either alki or lithium
battery. The actual operating cmos stand by voltage is appox 3v cut
down by series of diodes network.
A 4.5v will work but on many machines the real time clock will lag behind...6v
or 6.8 is always the best. JDR, Jameco, Battery-Biz
(http://www.battery-biz.com) and many others carry them as a norm and are
fairly inexpensive for the work they do the period they last. The only other
alternative is to leave the machine on and pray there's no outage.
--------------------------------------------------------------------
Russ Blakeman
RB Custom Services / Rt. 1 Box 62E / Harned, KY USA 40144
Phone: (502) 756-1749 Data/Fax:(502) 756-6991
Email: rhblake(a)bbtel.com or rhblake(a)bigfoot.com
Website: http://members.tripod.com/~RHBLAKE/
ICQ # 1714857
* Parts/Service/Upgrades and more for MOST Computers*
--------------------------------------------------------------------
4:02 a.m.
At 09:57 AM 3/23/98 -0800, you wrote:
I picked up an original PC/AT that has a dead lithium
battery for the
CMOS bios parameter storage. The battery says it's 6.8 volts. It's the
kind that is a 1/2x1x2 inch pack with a six-inch lead.
I've tried several places to find a replacement, but either a store
doesn't have it, or, if they have one, the voltage is not exactly 6.8
volts.
Thanks,
Dave
This battery should still be fairly common. You should be able to pick one
up from Radio Shack. I don't think the voltage has to be exactly 6.8. The
package should list compatability, if not there should be a listing in the
store with a P/N xref.
--
David Wollmann
dwollmann(a)ibmhelp.com
8:08 a.m.
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11:53 a.m.
This is a great idea, but after scrounging around, I got a replacement
for about the cost of this workaround. I found one place that wanted
$20
but finally found a Radio Shack that had one for a lot less. The
battery still cost a lot more than the PC/AT!
Thanks,
Dave
Tony Duell wrote:
I picked up an original PC/AT that has a dead lithium battery for the
CMOS bios parameter storage. The battery says it's 6.8 volts. It's the
kind that is a 1/2x1x2 inch pack with a six-inch lead.
I've tried several places to find a replacement, but either a store
doesn't have it, or, if they have one, the voltage is not exactly 6.8
volts.
So, what's the acceptable voltage range, especially on the low end? And
any good sources?
Well, the voltage is not that critical.
I also have a PC/AT (original type 2 system board), and the battery in
that was dead when I got it. It claimed to be a 6V battery. I managed to
find a place to buy a replacement, but it was \pounds 14.00 or something
equally crazy, so I made a replacement :
1N4148
+------->|------+----------( +ve
| |
----- /
--- \ 100k
----- /
--- \
----- |
--- |
----- |
--- |
| |
+---------------+----------( -ve
The battery was 4 AA alkaline cells in a standard holder. The diode/resistor
were added since 4 fresh cells gave about 6.6V, and I was worried about
killing my RTC chip. In theory it'll cause the battery to run down a
little faster, but mine's lasted about 4 years so far. I cut the cable
off the old battery and used that to connect my kludge to the system board.
And next time it fails, 4 AA cells are a lot cheaper and easier to find
than the official battery.
Thanks,
Dave
-tony 
12:07 p.m.
New subject: Apple ][ clones?
I used to be a big Apple ][ fan, but I really can't recall any early Apple
clones that match this description:
"Apple II clone, either a peach or an Apricot, looks like an Apple II, but
has extended keyboard, also has upper and lower case, shift keys work on
all characters, not just on a few like Apple II. Cover is White Plastic,
condition of cover and keyboard good. No label on cover. No identification
on Motherboard."
Any takers?
-- Doug
24 Mar
24 Mar
3:28 a.m.
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23 Mar
23 Mar
12:23 p.m.
At 10:08 PM 3/23/98 +0000, you wrote:
[snip diagram]
I picked up an original PC/AT that has a dead lithium battery for the
CMOS bios parameter storage. The battery says it's 6.8 volts. It's the
kind that is a 1/2x1x2 inch pack with a six-inch lead.
I've tried several places to find a replacement, but either a store
doesn't have it, or, if they have one, the voltage is not exactly 6.8
volts.
So, what's the acceptable voltage range, especially on the low end? And
any good sources?
Well, the voltage is not that critical.
I also have a PC/AT (original type 2 system board), and the battery in
that was dead when I got it. It claimed to be a 6V battery. I managed to
find a place to buy a replacement, but it was \pounds 14.00 or something
equally crazy, so I made a replacement : The battery was 4 AA alkaline cells in a standard
holder. The diode/resistor
were added since 4 fresh cells gave about 6.6V, and I was worried about
killing my RTC chip. In theory it'll cause the battery to run down a
little faster, but mine's lasted about 4 years so far. I cut the cable
off the old battery and used that to connect my kludge to the system board.
And next time it fails, 4 AA cells are a lot cheaper and easier to find
than the official battery.
FWIW, we've seen more than our share of 5170s in our time, and several with
CMOS supplies that consisted of a battery pack with 4 AAs. I've never
checked to see if this was an original P/N or FRU, but they all seemed to
work fine. IIRC, we've seen healthy ATs with 7.0V batteries, so the plain
old AA four-pack should probably work fine. If I can dig out my AT Tech Ref
I'll look up the spec and post it.
--
David Wollmann |
dwollmann(a)ibmhelp.com | Support for legacy IBM products.
DST ibmhelp.com Technical Support | Data, document and file conversion for
IBM http://www.ibmhelp.com/ | legacy file and media formats.
Thanks,
Dave
-tony
24 Mar
24 Mar
3:33 a.m.
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ard＠p850ug1.demon.co.uk -
djenner＠halcyon.com -
dwollmann＠ibmhelp.com -
jpero＠cgo.wave.ca -
rhblake＠bbtel.com -
yowza＠yowza.com