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Hardinge Conquest CS-42 power issues


Feb 6, 2022
Hi all, new member here, and I could use some guidance.

I recently purchased a 1988 Hardinge Conquest 42, tailstock model, no live tools. Pretty basic machine, and it is my first machine. I've been machining for 15 years and just decided to strike out on my own. However, I am having power issues. I am running a 20hp RPC from North American Rotary and am getting too high of a voltage at the machine leads. I am not an electrician, yes I should have hired one but here we are. I know I want to run the single phase transformer before the RPC due to the way my voltages are reading. I am thoroughly confused on the BB transformer sizing.

My legs are reading 245/245/255 +/-5%
As far as I understand, FLA is 51.2 amp single phase or 29.1 three phase.
when I calculate the kVa so I can size the transformer is when I'm losing it.

(249v nominal X 51.2 FLA)/1000= 12.749kVa

Am I missing something here? Like I said, I'm definitely not an electrician, but I'm doing this all alone and could really use some guidance on the BB transformer sizing. Thanks in advance.
I had that issue with my GT. The control transformer that Hardinge used had a lower voltage tap (seems like it was a nominal 95 volts) Tech support said change it and I did. Blown no boards or other components since. I had no alarms on my machine, mostly things popped at the voltage and current spike during power up. (Copied from the Hardinge forum post)

With a rotary convertor you need to make sure the control circuit on the lathe is connected the "native" line. That cicuit in my GT did have the multi tap transformer. The Hardinge tech said the controls need to run on real close to 115 volts. The rest of the lathe needed plus or minus 10% on the 220/230 volts(3 phase). We get by with 245 to 250 with our rural electric 3 phase for the rest of the machine. The GT did run on a dedicated rotary at the old location, but we did buy a premium CNC rated rotary for just that machine. The eleven other machines ran off a single regular 5 horse rotary.

That 255 sounds high but it may go lower with a load if you get the machine going. If not a buck boost transformer may be in your future. We added a pair of them to our AHC Omniturn as the braking resister would overheat when the voltage gets over 248. Buck boost transformers sound exotic but they are rather simple and I was able to install them myself. The hardest part was getting up and down as they were installed near the floor (old man problem).
Thanks for the insight FredC. I talked to an old buddy that does industrial maintenance and have determined that I need a buck boost transformer. I will be hooking it up tonight and will see what happens.

I have several servo and brake alarms and am working under the educated guess that the power is the culprit.
Any ideas then Ox? Everything Ive found here and other forums leads me to believe that this is the issue. Its Rated for 208-230.

Also, if anyone has a programmers and maintenance manual, either digital or hard copy, I'd be very thankful for a copy.
Per your servo errors?

Well, are you cycling power at the case level AFTER the RPC is up and running?

"Several Fanuc Errors upon boot up" sounds to me like it's all coming up together.


I've never known Fanuc to be all that picky about power.


Think Snow Eh!
Yes the RPC is fully running before I cycle power.

Alarms are as follows:

1008 spindle unit fault
1004 main spindle brake fault
400 servo alarm: overload
414 servo alarm: x axis detect err
424 servo alarm: z axis detect err
434 servo alarm: 3 axis detect err
Doo you have 24V?

You could post your control eh?
I'm guessing that it is an original "0"?

'88 is a bit older than my experience.

Bad power supply?
Did you see it run before you bought it?
How long's it been setting?


Think Snow Eh!
I've seen this 24v mentioned before but am not sure what it is in reference to.

Control is Fanuc 0T

I did see it running production and working well before I bought it. It was in storage for about 3 months.

I wired a buck boost transformer today and it lowered my voltage to a nominal 219v, but did not resolve any issues. I have checked every fuse and breaker I can find.
Your PLC normally works on 24V.
Your INPUTS from limit switches and such, and OUTPUTS to your valves and whatnot.

The outputs may be 120 in some cases, but your inputs will most always be 24V. (could be AC or DC IDK)

IDK what the inside of a 1988 machine looks like, but the 24V power supplies in my '90's T51's are on the floor inside the main cabinet.
I would guess yours to be the same?
Doo you have the yellow sectional PLC?
IDK when those started. If so, does it show much if any lights lit on the INPUT cards?
If so, then you likely have a good 24.

It might not be a bad supply either. Sometimes it just takes a bad wire or ??? to actually just "pull down the buss".
Meaning that if you check your output, it may read low or zero, but if you unhook the output wire(s), you may git'cher 24V back.
Then you need to follow your warrs back downstream to find where you are losing it.

(if 24 is the problem at all)


Think Snow Eh!
Ok that makes sense. I will check for the 24v. I am also going to check limit switches and whatnot because it seems that its in an emergency stop state. I don't know. Im really just checking everything at this point.
I would clean and reseat all motor and board connections. I had coolant get in a loose pin connector on a Z-axis motor once and it threw up a list of alarms even on the X-axis. Be aware it is common for Fanuc Ot's to have two power supplies. The black box and one that looks like in came out of a desk top PC.
I manually oved both axis off the limit switches and went through every wire connection I could find and found no loose wires. Neither helped. I am getting 24v. The spindle brake always locks as soon as the hydraulics kick in. I don't know if that's normal. I cannot move any axis, or go into edit mode. The machine will only stay in jog and wont actually allow me to jog, not even while holding OT release. I found the as shipped parameters sheet in the cabinet and all machine parameters are in tact.
1008 spindle unit fault
1004 main spindle brake fault
400 servo alarm: overload
414 servo alarm: x axis detect err
424 servo alarm: z axis detect err
434 servo alarm: 3 axis detect err

All the same as originally reported. Nothing seems to be changing at all when I power it up.
Maybe an issue with the Fanuc power supply?
I wouldn't have a clue what that looks like on your machine.

But there has to be something that is causing most/all of your issues.
Not likely forty-leven different issues.

How far did this travel?

Was it on air ride?

Have you confirmed phase direction?
Doo you have good hydraulic pressure?


Think Snow Eh!
I agree that it is likely one issue causing them all. The machine traveled roughly 40 miles. I dont know if it traveled on air ride. The riggers are very competent and I have used them before times. Phase is good and hydraulic pressure is good. It took some trial and error to get the power hooked up right.
Well, I finally decided to contact Hardinge. I should have done that to start with. They sent me all three manuals and all wiring diagrams for the machine. Still working on a solution but the Hardinge service team has been outstanding. Especially for supporting a 34 year old machine. I will post again when we have fixed the problem.

On another note, if anyone is in need of the operators manual, maintenance manual or programming manual for a Hardinge Conquest 42 with Fanuc 0T-B, I have those in PDF format and will gladly send them to anyone in need.

Thanks for the support from all that contributed here. This is my first machine purchase and I really hope I can get it running soon. Will report back when the issue is resolved.
After consulting with Hardinge, and sending pictures back and forth, It has been discovered that the spindle drive has no power. Not sure why yet but I am tracing wires and will locate the problem eventually. Hardinge tech said to check all breakers and fuses, which I have done, but I am guessing there is one that I missed or cant see.