Fanuc 5T not ready- How to troubleshoot?

79 Mazak M4 Fanuc 5T

A few weeks ago I was trying to make parts in a 15 degree shop and the hydraulic pump motor had a melt down (15 degree oil probably didn't pump so well). A winding in the motor shorted to ground, but the contactor heater did not trip. A filter capacitor exploded and a circuit breaker melted. Lots of smoke.

Last week replaced the motor first- It then would trip the heater about every 30 minutes, but the machine worked fine otherwise.

Today I Replaced heater and contactor and breaker feeding them and cut out filter capacitor. Went to start it up and the control sort of turns on? It turns on and the position display is on, but the main display is jibberish. says 4040404040 across the display and half the LED's are lit. Hydraulics don't turn on. Spindle drive does not come up. Of coarse the machine ready light is not lit.

All I did was replace a contactor. I even pulled out all the stuff I replaced and put the crummy burned stuff that sort of worked back in. No change.

The main board inside the refrigerator has a red LED lit that says +/-15. Batteries are good. All 75,000 fuses that I have found in the machine look good. There seems to be 24 volts in various places, but there are a bunch of power supplies scattered throughout the various cabinets.

This has been such a great machine. On one hand it's atleast 20 years past expired, but on the other it works so good and it ALWAYS works. It is hands down the most reliable CNC I have ever owned. Fingers crossed this is something dirt simple and I just knocked something loose in there.

Anyone remember how the 5T gets "ready"?

You have a wiring diagram for the machine? A Fanuc 5T maintenance manual? I think you're gonna need them. IIRC there is a 100VAC line through the e-stop switches that energizes a contactor in each servo drive. There is a 24V ready signal that goes through an auxiliary contact on the contactors in the servos and then to the CNC.

About the messed up display though, that is a wild one. No idea there.

Sounds like it could be a power supply problem. I've had this happen. One thing you want to do first. When your display is in gibberish mode, the machine can do weird shit, like the coolant will come on and off, the turret will start spinning for no reason, and also, the drives can rapid on their own. Before you do anything, I would suggest removing the power cables to both servo motors.

Inside the control cabinet there are 6 or so large circuit boards. Check the voltages on all of them. There are test points on each board, and finding them is a lot like playing "find the pope in the pizza". If I remember correctly, there are -15,-12, 05, +5, +12, +15 and +24 on each board.

I was within minutes of just dragging mine out to the parking lot when I discovered the -15 was dead on one of the boards. Was just a shitty connector. Now all is well again.

Trouble shooting a machine of that vintage can be tough.I have a Fanuc OT whose problem I have yet to figure out that has a dual axis shudder when cold. It will also throw up all kinds of crazy alarms if you even boot the machine up in less than a 55 degree shop. Why don't you warm up the cabinet and see if anything changes, something in there might not take kindly to the cold anymore. Once I warm my machine up it runs like a champ and will hold +/- .0002 all day.

P.S. I didn't know Portland got anywhere near that cold.

Dualkit said:

P.S. I didn't know Portland got anywhere near that cold.

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It normally doesn't. Last winter was pretty comfy with no heat. Maybe a weeks worth of days with lows in the 20's. This winter has been a different story. We had a several day stretch of lows under 15 and highs in the low 20's. We're getting a break right now. Highs are in the low 50's.

I have the wiring diagram, but not the 5T maintenance manual. I just made an offer on the 5T manual on ebay.

I'll poke all the voltages and see what shows up.

Garwood, I don't know jack about that control, but I have a couple heaters you are welcome to.

They are Dayton 15000 watt 240v 3ph.

I hear you about the cold- I lost a week- didn't feel like overnighting in the shop, and you know what I-5 is like when it snows.

Nice today though.

Last summer I thought I would get ahead of the heat- after 3 years in a row of 100 degree July's. So I bought a 36" port-a-cool for the shop and a little AC unit for the office, and it never got hot so I only used them for a week in August...

guest said:

Garwood, I don't know jack about that control, but I have a couple heaters you are welcome to.

They are Dayton 15000 watt 240v 3ph.

I hear you about the cold- I lost a week- didn't feel like overnighting in the shop, and you know what I-5 is like when it snows.

Nice today though.

Last summer I thought I would get ahead of the heat- after 3 years in a row of 100 degree July's. So I bought a 36" port-a-cool for the shop and a little AC unit for the office, and it never got hot so I only used them for a week in August...

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I built a shop and moved simultaneously about a year ago. The shop is still in process and slowly getting finished. I have a big furnace that I need to install, but other things have to go in first. It's a time and money deal. I appreciate the offer.

I should have taken the week off. I had stock tank heaters in all the coolant sumps and dish heaters on the VMC tables when they weren't running so the coolant wouldn't instantly freeze onto the table/parts when running. Over that week I lost a spindle drive on a VMC and the hydraulic pump motor on this lathe. Made no money at all and froze my ass off.

Back to the original issue with the Mazak/5T- Took yesterday off to help a friend and spent the evening with my family. This morning the lathe fired right up and worked no issues at all. I think Larry Dickman's right about a bad power connection on one of the boards.

I just ran out of De-Ox spray so when I pick up some more I'm gonna give all the connectors in this old thing a spritzing.

Glad your control's back up.

I came in one morning and the LCD display on my height gage was froze. Put it in the office for a few hours to thaw and it returned to normal.

After that experience I started leaving it in my office overnite, with a little space heater running.

Glad to hear it's going again. Mine has done it twice, the first time it was unusually cold, like mid- 20's. At first I thought is was the power supply. A refurbished one was 2X what I paid for the machine. What I found is, on all the power connectors, all 8 thousand of them, the contacts loose their springiness and don't make good contact with the pin on the circuit board. If you pull them out of the connector body, bend them out a little and push it back in, then they're fine.