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Gateway 2000 4DX2-66 Mini Desktop CMOS battery/manual

Z

Zippy Zapp

Experienced Member
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Dec 13, 2014
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259
Location
USA:CA
Hello,

After spending the past 2 days scouring everything I could on here and the internet looking for information on CMOS battery for this model I thought I would post in case someone here knows the answer.

I have a Gateway 4DX2-66 mini desktop. I have attached Pics so you can see the motherboard and connector. It has a 4 pin battery connector, 3 pins actually, since one is removed. I have the connector and the red and black wires but no battery that goes with it. This model has a Dallas DS12885 RTC, not the kind with a built in battery. According to the datasheet for that IC it looks like it expects 3V on the vbat input pin. So I am assuming the battery should be 3V too. But I don't like to assume and I don't want to guess and fry something.

I have seen some Gateways with the 66V tower motherboards use a Rayovac 4.5v pack. I don't remember seeing a large pack connected to my original. If it is 3V that is easy enough. A CR2032 battery should do the trick or a couple of AA's in a battery holder too. I verified that the pins are not receiving a charge so it is not a rechargeable battery.

Does anyone know for sure about the Battery?

Also does anyone have a PDF manual or scan available for this Gateway?

Thanks!

Battery Connector:
IMG_0302.jpg

RTC Chip:
IMG_0303.jpg

Motherboard:
IMG_0304.jpg

Case:
IMG_0307.jpg

History of this machine:
Has had 1 owner and is not yellowed. Has all original hardware including telepath modem, Ensoniq ISA sound card (Long card but looks like it needs caps as the solder pads look a little crusty.) Also original floppy, NEC CD and 750mb HD with original DOS/WFW3.11 install including the always cool gateway 2000 cow in space wallpapers. I will for sure image the drive just in case. I can verify the original hardware because Gateway always put Serial# and Date on labels on all their hardware of this era. Everything matches. HD, Floppy, sound and modem removed for these pics.
 
Last edited:
vwestlife said:
Look for a Rayovac 840 equivalent 4.5 volt computer battery:

http://store.batteryspecialists.com/844a.html

A holder for 3 AA batteries would be cheaper but you'd probably have to add the connector yourself. I looked but couldn't find a 3 AA holder with the appropriate connector on it.
Click to expand...

If you hunt around you can probably find a 3xAA or 3xAAA holder that has the connector on it, if not, just cut one from some defunct equipment and solder it on. Then velcro the pack somewhere in the case and you'd be good to go. Cost you less than $4 in most cases, there is no need to spend $10+ on that Rayovac battery.
 
Thank You all for the info. I do still have the connector so just need to solder it on to the 3AA holder. I think I have one of those laying around someplace. So this get's fed 4.5v. I had a feeling it was 3v so I am glad I asked.


Cheers!
 
Can anyone tell by looking at the motherboard picture I posted who makes the motherboard? Is this an intel made MB? I know gateway basically used only a few manufacturers for the MB in those days.
 
Zippy Zapp said:
Can anyone tell by looking at the motherboard picture I posted who makes the motherboard? Is this an intel made MB? I know gateway basically used only a few manufacturers for the MB in those days.
Click to expand...


Read this (specifically Q1):

http://webpages.charter.net/dperr/micronics/anigma.htm

I have one of these machines that originally came with an Intel Classic R board. The pictures you have posted do not look like the Intel board.
 
Stone said:
Because that's what works best:

http://aitotat.blogspot.com/2013/07/external-battery.html

http://pc-restorer.com/replacing-cmos-batteries-in-old-pcs/
Click to expand...

Neither of these articles suggest replacing a Dallas RTC battery with a 4.5v battery. In the rework mods, the author always installed a 3V coin battery. The only references to using a 4.5V battery are when replacing one of those barrel batteries or a Varta type battery.

If I have a machine with a Dallas DS1287 with built in battery that has died, I always replace it with a DS12885 and external battery.
I'm certainly not going to do any "special study" on the effects of using a 4.5V on a Dallas RTC chip.

I try to stick with the manufacturers recommendations, but that's just my opinion.
 
Chuckster_in_Jax said:
Read this (specifically Q1):

http://webpages.charter.net/dperr/micronics/anigma.htm

I have one of these machines that originally came with an Intel Classic R board. The pictures you have posted do not look like the Intel board.
Click to expand...

Thanks for confirming that. It must be the Micronics or Anigma.


Chuckster_in_Jax said:
The datasheet for the Dallas DS12885 says "A lithium coin-cell battery can be connected to the VBAT input pin on the DS12885 to maintain time and date operation when primary power is absent."

Also shown is:
VBAT Input Voltage Min: 2.5 MAX: 4.0 V

So why is everybody suggesting a 4.5V battery?

http://datasheets.maximintegrated.com/en/ds/DS12885-DS12C887A.pdf
Click to expand...

That was my initial thought too as I read the datasheet but I had read so many things about 4DX models that used the 4.5v I wanted to be sure. It seems some 4DX models used the 4.5v, particularly the ones in the AT cases. My original 4SX-25 had a CR2032 coin cell on the main board. Bought that in early 1994. This DX2 model is a late 1994. Just for the heck of it I wired a CR2032 to the connector and plugged it in. The replace battery message was gone and it kept the settings after a quick test of unplugging it and leaving it set for a few...

It seems from the links posted after your message that some battery packs were using the 3.6v lithium battery that is also used by many Macs of the era.
 
The supply thing is a matter of whose lie you beiieve. The DS12885 is claimed to be a drop-in replacement for the DS1285, which in turn, claims to be a drop-in replacement for the Moto MC146818 RTC. If we go to the datasheet for the 818, we see that there's no Vbat input; it's shared via diode with Vdd. An ordinary signal diode drops 0.6-0.7V, so that the use of a 6V backup in the old machines wasn't uncommon (several of my old 386/486 systems use a 4xAA cell holder. So what's behind the claim of "drop in"?

Dunno, but half a volt isn't much and the datasheets are no help. If you're worried, put a diode in series with your 4.5V supply. Myself, I'd grab a coin cell holder.
 
Just as an update I went with a 2AA holder, so 3v. This has worked perfectly and the time is in sync after being powered off and unplugged for 2 days. If there is going to be a time sync problem, as suggested by some of the links posted here, then I can always adjust. I am going to measure the voltage at the vBat pin to see what it reads. I have a feeling that some systems that people are plugging in the 4.5v battery packs to have resistors between the battery connector and the RTC/NDRAM/PRAM to cut down that voltage to 3v. If they are using a Dallas chip, anyway.


Now I just need to figure out the floppy problem and this computer is done.
 
A resistor won't do it because the current drain is small and not constant. A diode, transistor or PN junction of any sort would be adequate and costs about the same--and has the benefit of protecting the device should you install the batteries in backwards.
 
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