Battery Question - Two sets?

[John3]

My Fanuc 5T has two sets of batteries.

A string of 3 D-Cells connected to the bottom board A20B-0004-050 which appears to be a memory card and it has the tape reader interface.

And a string of 3 small LR44 watch batteries that are attached to the top board A20B-0003-0744-08C which appears to be the CPU board.

My question is, what is each set responsible for keeping memory of?

The top watch batteries were allowed to discharge and the machine turned off. Everything still seems to be there, parameters and last program offsets, but I'm sure Fanuc didn't put those batteries there for no reason.

TIA for any comments.

[Dan Fritz]

The small battery on the top board keeps the paramters and the tool offset data in memory when you shut the power off. There is a small "6508" IC near the battery that is a CMOS static RAM chip. If that IC loses power, your parameters, tool offsets and the "setting" data under the "SET" register is lost.

The bare-bones Fanuc 5 didn't have the memory & edit function at all. It was basically a "tape only" machine. The Memory & Edit option included that smaller board, the operator's panel with the ALTER, INSERT, ERASE (etc.) buttons, and the battery. The Memory & Edit board has a bunch of those same 6508 chips, and they hold your part program data.

You should get a battery alarm LED on the main panel if EITHER of those batteries goes low. Remember, if you get a battery alarm, you can keep things in memory by just leaving the CNC power on until you get a new battery. Replace the battery with the CNC power ON, that way you won't lose your data.

I've seen people rig up a jumper to connect the lower (large) battery pack with both boards. That works OK too, and it eliminates the need for 2 batteries. You just need to be sure that those 6508 aren't deprived of 5v power. You can make your own battery packs using three 1.5v alkaline batteries linked together in a pinch.

[John3]

My small batteries "up-top" were dead when the machine was turned off and they were really dead .2v total.

The machine does seem to have some problems now, but many of the parameters seem to be there, Some don't match the original listing I have. Sounds like I should reload the parameters from the listing?

What do you think?

John

[Dan Fritz]

Yep.

Turn on the parameter write enable toggle switch on the back of the MDI panel, put the control into MDI mode and key them in one by one. Unless you have a very early model 5T, you should be able to just key them all in.

The very early 5Ts needed to load the option parameters from a tape, but those are pretty rare.

Be sure to turn off that toggle switch when you're done.

[NC Cams]

Dan:

My 5T has some hand crafted cells (3 each top and bottom) soldered together as the back-up cells. Trouble is they are A's, C's and D's in 3 separate machines.

I've wondered if it wouldn't be easier to get a 6 volt lantern battery or even a 9vdc transitor radio battery or even a small 12 volt sealed cell and affixing it to an LDO 5v regulator chip. Then feed both upper and lower boards with a true 5vdc back-up from a common current source.

Why?

I'm tired of seeing six packs of batteries of 3 different configurations hanging around in my 3 lathes and feel that a single, larger battery or a "plug in" transistor radio battery design would be easier to craft up.

Besides, it would be much more sanitary and convenient than soldering C, D or A cells together when I need to replace them as I have to do now.

[Dan Fritz]

A regulated power supply would be fine, so long as it's around 4.5 to 5.5 volts DC. Three 1.5v "C" or "D" batteries work fine for about a year on the memory and edit board, and they're pretty cheap to replace. You can get a battery holder at Radio shack and just solder a couple of wires to the connector on your old battery pack.

The added trouble of putting a regulator on a 6v or 9v battery is fine too. Just don't feed the control more than about 5.5 v.

[NC Cams]

The R/S battery holders work fine, IF you don't have an atmospheric corrosion problem which we find occurring a lot on alkaline's.

Regulart flashlight batteries have less capacity and have a voltage drop off problem too and a corrosion problem too.

THis is why we're looking at a LDO soldered to a to a rechargeable device or some other other higher capacity device. We're looking for a way to eliminate the yearly battery change ritual.

[John3]

Thanks Dan for the suggestions.

Following your instructions I was able to re-enter most of the parameters from the original machine builders hand written sheet.

Most but not all.......

Some of the higher number parameters would switch back to some other number after I pressed input. These were:

Param # Original Sheet Machine display
------- ------------- ---------------
68 0101 0001
70 1110 0010
76 0001 0000
78 0101 0111

I entered the "Original Sheet" value, but upon pressing [INPUT] the display would revert back to "Machine display value"

What do these parameters do, and is this any sort of problem.

TIA,

John S