common converter problem questions

[metlcutr55]

my nardini fasttrace lathe was running great when shut down for a 2 week vacation. upon return, the lathe wont come up, the common converter (alpha series) shows an 8 code (regenerative control circuit abnormal), wont power up the amps etc. looking at diagnostics, d014 (wait reset esp rrw off 1) comes up with a 1 code, and both x and z axes in d200 (servo detection) come up with a 1 code under dca (regenerative discharge alarm)

my tech who has spoken with fanuc says replace the common converter. he's new to me and seems sharp, but im not an electronics guy, and have tried other techs some good and some not so. and fanuc's solution to about everything seems to be send 2 guys out replace modules stay in a nice hotel eat well i can pay for it and pay a squillion bux an hour for labor. oh yea question 1, does this diagnosis sound correct? id hate to buy a converter and find out a mouse ate a cable in the bowels of this thing somewhere. and if youre reading this Rob, please take no offense, im a paraniod cheap yankee who triple checks my own every move

question 2, possible lightning strike? its been that way around here, tho the lathe was off as was the rotary phase converter that drives it. reason i ask is l lost a desk computer to lightning about the same time. and insurance pays me for lightning damage.

question 3, i have a new unit available for around $1200, a refurb for $200 less. which one? new sounds better but i was forced to use a refurb servo motor a couple years ago and its been great.

thanks in advance!

[NC Cams]

NOt familiar with whatever version of control you have on a Nardini but I'm familiar with the gremlins of a Fanuc 5T lathe.

Fanuc was really chintzy with my lathe. They used cheap, lame a$$ tin coated connectors and pins on everything as opposed to Mil spec "gold" plated ones which don't corrode. Result: the normal atmospherics, especially those in plant, corrode the cheap tin terminals. Since you're dealing with micro amps (TTL/low voltage signals), it don't take much for a corroded connector to NOT conduct, especially after a period of inactivity that would allow the connector to remain vibration free - vibration might keep the joint sound enough to work but, without it, rigormortis induced electronic gremlins. You can't see electrons, therefore you can't trust them.

When our machine all of a sudden won't come up, we spend the day cleaning/tightening connectors. It comes up pretty near all the time after that. Wev'e even taken to regularly doing it when we're doing P/M on the machine.

If you have a BTR and it is NOT opto isonlated, you could have had a power surge that took out the board due to a ground loop thru the PC and into the Fanuc M/B. That little episode cost me well over $2k to learn and nearly as much again when parts got reassembled wrong (reversed 50 pin connector) after the reassembly process.

Yes, it will work BUT all it takes is the errant situation where a surge sends a ground loop thru the PC into the M/B on the Fanuc. We ultimately found a 13V difference between "ground" between the PC negative on LPT port and the "ground" on the Fanuc. SInce TTL chips will tolerate 5.6vdc max, we toased the SOB's big time.

Depending on the model, Glenn Rowe at Billor Ent (888-424-5567) in Texas can service them and he's much more reasonable than Fanuc. He even bench evaluates them. If they work there, the issue is in the cabinet and that isn't always fun to deal with.

Why? depending on machine maker, they don't always document all the connections. An undocumented ground that shouldn't have mattered, did and kept me from restarting the machine for darn near 2 weeks of chasing everything down. Only a SWAG redundant tying of grounds together (overkill I learned someplace) solved the problem.

If Fanuc used true Mil spec interconnects, this wouldn't happen. But they use(d) lame a$$ "amp" style connectors like you'd use for the power plugs on a PC's HD. REAL expensive call girl only she wears K-mart panties.

I'd guess that (hint) if the PC that got fried by the lightning was attached to the Fanuc and had the grounds NOT optically isolated as mine were not, it is quite possible that your insurance people might get to know the folks from Fanuc and/or Mr. Rowe.

P/M me for the address to send my service fee - no matter what it is, its gonna be cheaper than Fanuc - and I won't bill you for dinner, either. 8-))

Some refurbs are factory warrantied pieces - brand new but infant mortality for some reason or even return unused but can't be sold for new. Look at the warranty and judge accordingly. If it is a factory piece, the refurb should be OK - aftermarket refurb, depends on who did it... A guarantee from an outfit the goes/went bust is pretty much usesless.

[Al_The_Man]

question 2, possible lightning strike? its been that way around here, tho the lathe was off as was the rotary phase converter that drives it. reason i ask is l lost a desk computer to lightning about the same time. and insurance pays me for lightning damage.

I know of at least one customer of mine that loses a spindle drive often when electrical storms are in the area on a Alpha system, the last I heard he was looking at putting another 3 phase reactor on the line in.
It depends on the machine tool builder, but I believe the AC Control input is often connected to the Power Supply unit on those sytems, even when the main three phase contactor is off, this could mean that there is power on the Power supply control unit, until the main disconnect is switched off, which if you are shutting down for a couple of weeks, or even weekends, is a good idea to turn off.
Al.