[69owb]

Hi
I have a Mazak M5 lathe with a Fanuc 2000c Control. We have never been able to get it to run. A service guy from Mazak came out to look at it a couple of years ago. I don’t think he had a clue of what was wrong with this machine just told us to send off one of the velocity drives to get fixed. And see if that fixes the problem. OK the other day I was reading some post on if the batteries go dead you loss your parameters and you will get a parity alarm. So checked the batteries. The Battery on board #9 measured 4.8 volts, so I thought that one might be fine but the battery on board #10 was dead. replaced the battery turned the control on. I can’t get it to do anything. The parity light is on and it shows 16080206 or 12080206 on the display when you turn the control on and that’s all it will do you can’t turn anything on or off. I'm debating on finding a service manual because I don't know if it's worth fixing or not. Any ideas on where to start on this thing. Thanks

[GPena]

That is an old control, maybe it is better if you think in a retrofit for that machine. you can use the same drives and motor and save money that way.

GP.

[Dan Fritz]

Most of those 2000 controls had a bank of 16 LEDs on the CPU board (slot 8). When you turn the control on, reading those LEDs in Hex will tell you where the CPU has stopped. Let me know which LEDs (from left to right) are on and I'll give you the Hex address. A Fanuc technician with some knowledge of the 2000C should have a memory map of the control, which would show what ICs (RAM, ROM, or CMOS RAM) are causing the parity alarm.


My guess is that your CMOS memory chips that hold the parameter data lost power and you need to clear the memory and reload the parameters to get the control back. Assuming that all the boards are healthy, you should be able to clear the CMOS RAM and get the control to boot up "stupid" (no options). You can then manually enter the parameters if you have them written down somewhere.

Sometimes parity alarms happen on these controls due to a hardware problem (a bad board, bad connections between the boards and the backplane, etc.). You can plug/unplug all the boards from the backplane to be sure they're all well seated.

The most likely cause is junk in the CMOS RAM though. I'm trying to remember the procedure for clearing the memory. I seem to recall that there is a toggle switch behind the MDI display board called "PRM". With this switch on, you can enter and erase parameters. I know that to clear the parameters you must turn this switch on, then power up the control while holding two keys. I can't remember which two keys these are so maybe another forum member will chip in here ... I would try CAN and RESET, or CAN and INPUT, or RESET and INPUT. You might also try holding just ONE key while powering up (INPUT or RESET). Guessing wrong should not do any harm at this point. You'll have to re-enter the parameters anyway, and there aren't very many on the 2000C

If the memory is cleared and the parity alarm goes away, the control may come up "READY" and enable the servos. As a precaution, I would pull the fuses on the servo drives just to be safe ... If you have a slant-bed machine, you may want to also put wood bocks under the crosslide so it doesn't drift down if the control powers up with no fuses.

I'm at the Westec show in LA right now, so I don't have access to my old manuals. I hope this info gets you heading in the right direction.

[69owb]

Hi Dan Thanks for the help. I Fired the machine up looked at the LED’s there are 4 banks of 4 LED’s and 1 bank of 2 LED’s. 8,10,11 are not lit up the rest are all on except PL2. I tried to reset the control no luck It doesn’t seam to do anything at this point. Maybe I’m not hitting the right button yet . Do you know off hand if the maintenance manual will have all the parameters in it Thanks again

[Dan Fritz]

The hex address where it's hanging up is 0B00. I don't think that's in the CMOS RAM area, so it's probably one of the ROM chips on the memory board (board 9). A common problem with those controls is a ROM chip that's not well seated in the socket. Try pulling out the memory board and putting it on a clean bench (use towels or somthing clean under the board) If there is a lot of gunk on the board, try to clean it with a soft, dry brush. Then, push on each of the ROM chips (there are a lot of them) so they're well seated in their sockets. Also look for "bent under" pins or pins that are splayed out and not making contact with the socket. Sometimes a ROM chip will function well for years, and then it will slowly come loose due to heating & cooling cycles of the control.

You will also notice many empty sockets. This is where "option" ROMs are installed for software options. If you have a parameter set for an option that's not plugged into the memory board, the CPU will try to address an IC that isn't there, causing the parity alarm. That's why zeroing out the parameters is important. A loose ROM chip or lots of dirt on the board can also cause it.

When I get home tomorrow, I'll look to see what's at address 0B00. It may not be a ROM chip. If it is a ROM chip, that address should narrow it down to one of just 3 ICs on the board, which you can check more closely.