Old EPROM questions

Assuming they're in the usual cheap sockets, I'd probably destroy the sockets with a scalpel and bend the fingers out before removing the EPROMs. In equipment that old, the pins may be corroded, and you don't want one to fall off.

Cheers

Phil Hobbs (Who has a lab full of top-of-the-line boat anchors. Love 'em.)

I'll check to see if they are stuck. I don't think they will be though because I have worked on even older FANUC controls and they all seem to have been made pretty with pretty good components. I do have some of theat DeOxit5 contact cleaner. Should I spray some on before attempting removal? Eric

I'd think a spray of DeOxit would not hurt. It is rare for Eproms to corrode though that depends on the storage environment I've pulled thousands over the years from our arcade games from the 70s and 80s and only a few legs had rotted. But those are easy to spot as the pins look black!

If the leg is looking rotted consider unsoldering the EPROM socket with the EPROM still installed. Then, leaving the EPROM in the socket, read it in your programmer. Freeing the legs of the socket can be fun, best to use a Pace or similar desoldering tool that allows you to move the leg around while you are sucking the solder out.

John :-#)#

Remember that the EPROMS are static sensitive. Use appropriate anti static procedures when working with those chips.

Google ESD for more details.

You're right about Fanuc using decent components. Contact cleaner makes a mess and is not necessary.

It something like this Fanuc board? I used to help the owner of a local machine shop maintain a Mori Seiki MV35-35 5 axis machining center, with a Fanuc something controller. For upgrades, I never had a problem removing or inserting the EPROM's. The coolant and oil fog that usually surrounds these machines does a nice job of preventing corrosion. Watch out for the dehumidifier, where condensation might make things rust.

Just pry out the EPROMS with a plastic pry tool or "spudger" (to prevent cracking the ceramic EPROM case). Something like these:

Also, take a photograph of the PCB before disassembling so you can put the EPROMs back in the correct socket.

For saving the EPROM contents, there are cheap EPROM burners available on eBay. I have one like this: About $50 on eBay: However, there are some tricks involved and it's all too easy to make a mistake and trash an EPROM. If you're going to do this yourself, I strongly suggest that you first practice with some junk EPROMs.

Good luck.

Greetings John, Fortunately the circuit board shows no corrosion. I do have a tool made for removing these chips so I'll just give 'em a squirt. let the stuff work for a bit, and then pull 'em. Eric

If no signs of corrosion, then I would not spray the board with anything.

Take great care that you do not damage traces under the socket when you are prying out the EPROMs.

John :-#)#

Greetings Jeff, The board I am replacing has only 6 EPROMs but still looks similar. Thanks for mentioning picture taking, I will for sure be doing that. I didn't know the programmers were so inexpensive now. Since I have lots of old EPROMs from a few other FANUC controls I am gonna order a reader/programmer and see if I can copy the junk ones. So I'll be asking for advice soon about which programmer to get for my particular devices and how to avoid scrapping them. Thanks, Eric

I will for sure be taking all precautions regarding ESD. Eric

Good idea.

Cheers

Phil Hobbs

This is the one that I use: $30 plus $10 shipping. Maybe add about $15 for a 9V power supply, DB25 extension cable, and USB cable.

There is a later version that runs on a USB port: $50 plus $14 shipping.

Notice that it uses a parallel port computah interface. Don't bother trying a USB to parallel adapter cable. It won't work. Don't use a ribbon cable for a DB25 extension. Mine went intermittent from bouncing around in my car. I wasted a few days finding the problem.

The hard part is getting the jumpers and switches correct. Don't guess. One wrong switch or jumper and your device is blown. Also, pay attention the EPROM manufacturer. Even though the chip number might be similar, each mfg has a different voltage, timing, and programming algorithm.

You'll also need an EPROM eraser. I suggest you get one with a drawer that can handle more than one EPROM at a time. The UV light does not last very long. If you're erasing one at a time, you'll burn out the light after about 500 erases. The really cheap ones are fine and all the mechanical timers are noisy and obnoxious.

As I discovered in my youth, EPROMS can go into a socket two ways around. One way is good, the other way is bad. When the supply and ground pins are swapped like this, the bond wire melts and you can even see the melted remains through the quartz window, which somehow makes it more frustrating. If you are going to make this mistake, at least do it AFTER you have a copy of the contents!