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Amigaz
March 5th, 2008, 11:00 AM
I recently aquired an old 386 motherboard which looks pretty much like this one:

http://stason.org/TULARC/pc/motherboards/A/ATLANTIC-COMPUTER-PRODUCTS-INC-386-SER-386C.html

With it came an external CMOS battery with a 4pin connector and one + and one + wire from the battery connected to it like this -+oo

o = empty hole in the connector

The external CMOS batter connector has 4 pins...the first pin is labeled "1" and the last one "4" but I have no clue on to which too pins to connect the battery without frying something...please help me

Dwight Elvey
March 5th, 2008, 01:18 PM
Hi
I assume you have a volt meter??
Dwight

Amigaz
March 5th, 2008, 09:01 PM
Hi
I assume you have a volt meter??
Dwight

Of course but how do I use that on the pins on the motherboard to find out which is ground and positive?

MikeS
March 6th, 2008, 05:29 AM
Of course but how do I use that on the pins on the motherboard to find out which is ground and positive?
---
I had the same response, how's that going to help, but if you use the Ohmmeter you could check which pin is ground (-)

m

Unknown_K
March 6th, 2008, 08:32 AM
Look at the old battery connector, pin 1 on the cable should have a mark on it like an arrowhead, that connects to pin 1 on the motherboard.

Amigaz
March 6th, 2008, 11:08 AM
Look at the old battery connector, pin 1 on the cable should have a mark on it like an arrowhead, that connects to pin 1 on the motherboard.

Soryy, but there's no such arrow on the battery cable connector

Hey...nice to see an Amigan here :D

This is a pic I took of the battery connector, sorry for the crap photo...I really suck at taking quality photos

As you see one hole is blocked (white dot)

http://img442.imageshack.us/img442/2763/p1010310sq6.th.jpg (http://img442.imageshack.us/my.php?image=p1010310sq6.jpg)

Terry Yager
March 6th, 2008, 12:48 PM
In my limited experience, the (+) pin is usually the most inboard of the connector. YMMV

--T

MikeS
March 6th, 2008, 12:52 PM
Soryy, but there's no such arrow on the battery cable connector

Hey...nice to see an Amigan here :D

This is a pic I took of the battery connector, sorry for the crap photo...I really suck at taking quality photos

As you see one hole is blocked (white dot)

http://img442.imageshack.us/img442/2763/p1010310sq6.th.jpg (http://img442.imageshack.us/my.php?image=p1010310sq6.jpg)
---
Yeah, connectors with arrows are rare indeed.

If you're sure that's the correct battery, the black wire would probably go to pin4 but I'd still check with an ohmmmeter as I suggested.

Usually, pin1 is + and pin4 is gnd, with pin2 removed. You don't say whether there's provision for an on-board battery, so it may well be that in your case pin3 is used for the positive terminal; make sure there's no continuity between pins 3+4.

m

modem7
March 7th, 2008, 12:58 AM
1. Per what Mike stated, the norm is that pins 1 and 4 are the wired ones, as shown at http://members.dodo.com.au/~slappanel555/misc/BATT_2.JPG

2. What is also normal is that the 4 pin external battery connector on the motherboard (J8 in your case) has one of the inner pins removed/cut, and that together with the fact that one of the holes in the battery connector has been plugged (the white peg), means that one can't plug the battery connector the wrong way.

3. Something to be aware of. Some motherboards that have provision for both an on-board battery and an external battery, have a jumper to control which battery is used. I didn't see such a jumper listed on the motherboard layout that you pointed to.

Amigaz
March 7th, 2008, 02:58 AM
1. Per what Mike stated, the norm is that pins 1 and 4 are the wired ones, as shown at http://members.dodo.com.au/~slappanel555/misc/BATT_2.JPG

2. What is also normal is that the 4 pin external battery connector on the motherboard (J8 in your case) has one of the inner pins removed/cut, and that together with the fact that one of the holes in the battery connector has been plugged (the white peg), means that one can't plug the battery connector the wrong way.

3. Something to be aware of. Some motherboards that have provision for both an on-board battery and an external battery, have a jumper to control which battery is used. I didn't see such a jumper listed on the motherboard layout that you pointed to.

I'm starting to think that the seller just threw in this battery and it doesn't fir my motherboard since it has 4 pins
The old battery has been removed, the legs are cut off

Dwight Elvey
March 7th, 2008, 06:53 AM
Of course but how do I use that on the pins on the motherboard to find out which is ground and positive?

Hi
I can think of two ways.

1. Turn the computer on. Measure the pins and note the polarity
with the meter. ( assuming the computer is suppose to use
NiCads. If it is suppose to use alkaline cells there is no voltage
on the pins. )

2. With the computer off, locate a TTL DIP part. The pin on the side
with pin 1 that is on the opposite end is ground. Also most machine have
a direct connect of ground to the metal chassis. Measure with the
Ohm meter to determine ground. It should be close to zero ohms.

The black lead on the pack is usually the negative lead. This should
go to ground. Check with meter to match with the computer.

Dwight

MikeS
March 7th, 2008, 11:26 AM
Hi
I can think of two ways.

1. Turn the computer on. Measure the pins and note the polarity
with the meter. ( assuming the computer is suppose to use
NiCads. If it is suppose to use alkaline cells there is no voltage
on the pins. )

2. With the computer off, locate a TTL DIP part. The pin on the side
with pin 1 that is on the opposite end is ground. Also most machine have
a direct connect of ground to the metal chassis. Measure with the
Ohm meter to determine ground. It should be close to zero ohms.

The black lead on the pack is usually the negative lead. This should
go to ground. Check with meter to match with the computer.

Dwight
-------
Sounds good; an easier-to-find ground is on the center pins of the PS connector.
I think you'd be pretty safe moving the red wire on the connector to the other end, removing the key plug (or bending pin 2 out of the way) and connecting it with red to pin 1 and black to pin 4 (after confirming that pin 4 is indeed ground).

There is usually a diode & resistor to deal with a reversed connection, but I take no reponsibility ;-)

m

Dwight Elvey
March 8th, 2008, 08:56 AM
Hi
Do be careful to match the right type of battery. Most external
batteries use not rechargeable alkalines. These must not be
connected to the charging circuit if a NiCad circuit.
Most of the time, if it is desired to do this, one can remove the
charging resistor that would supply the current for the NiCad
and replace it with a blocking diode.
Dwight