New (to me) BMC-20!

[fasto]

I just got a BMC-20, it looks to be a nice machine once I get it going.
Since there seem to be more Hurco experts here than anywhere else in the world, I thought I'd join up!

I am having some troubles with the BMC-20. I was worried about control problems, happily the control seems to run great, it's got an upgraded memory board with good lithium AA cells so that's good news.

The bad news is that there's some trouble with the Fanuc 3-axis servo drive, fanuc # A06B-6050-H401, which is an AC drive using red cap servos. As soon as I power up the machine, the drive shows a TG error LED on the Y-axis. A little later, it also lights OC on the Y-axis. I did exchange the X-axis and Y-axis on the control (motor, encoder, control) and the error stays with the Y-axis DRIVE. From what I've read, TG is an error with the motor feedback. I'd guess OC is probably overcurrent. Keep in mind that the control hasn't booted yet, or enabled the drive yet, so the overcurrent can't be for real.

Fanuc provides five error line outputs, but Hurco doesn't hook them up or provide any info on what they mean. I hooked them up, and one of the Y-axis lines is showing 24V with all the rest at 0. So, the drive is trying to tell me something.

I don't have the Fanuc book for the drive which is supposed to be B-54765E. Would the book describe the meaning of the LED's and the error lines? I can fix this, as I believe it's most likely a blown up op-amp, optocoupler, or logic gate but it'd be great to know where to start!

Thanks,
Aaron

[bloke]

Broken cable to the encoder on X.
There are three jumpers on the front of the drive marked S10L, S10M and S10N. These are by default set to the top two pins. Move these jumpers to the bottom two pins on all three to disable the TG alarm function.
Power up and verify the fault has disappeared and then move the S10L jumper to the top position. If the alarm reappears, the fault is on the X cable. Double check by restoring the jumper to the top position on all three axes one at a time. Replace the cable that is causing the problem but be sure to check the wiring as there is a link in the encoder plug that swaps the direction of travel for the X.

[fasto]

Hi Bloke, thanks for both replies.
What I was testing, I shifted all the X-axis connections to the Y-axis, and the Y-axis to the X-axis at the drive.
That is, I exchanged CN1L and CN1M, CN5L and CN5M, CN6L and CN6M, 5L/6L/7L and 5M/6M/7M. I would have expected the error to follow the cabling that I swapped, if the cabling were the problem.
(Later...)
I just looked at the drive, and the S10L is already on the bottom pins! The S10M and S10N are on the top pins. So, I might have bad X and Y axis encoder cables. I will do some more testing after I get some other work done.

I did see the A & B signals crossed on one of the encoder wires, thanks for pointing that out.

Does the drive manual that I don't have contain the function of all these pins? I guess I will have to go get it.

[bloke]

I can fill you in on the pin functions. Let me know when you need them and I'll dig 'em out.

[fasto]

Originally Posted by bloke I can fill you in on the pin functions. Let me know when you need them and I'll dig 'em out.

I'd be thrilled to have them, at your convenience.

I editied my original post, as I wasn't clear that the error stays with the Y axis on the drive when I swap cables around. I'll do more checking later.

Edit: moving the S10M jumper (Y-axis) does keep the Y/M TG light from coming on, as I expected.

I put the S10M jumper back to the top pins. Then, when I move another axis' cabling to the Y-axis servo (the M servo), the Y/M TG light comes on, no matter which axis' cables are on the Y/M servo amp.

Based on this, I think the cables on the machine and the motor encoders are probably OK.

I exchanged the 40-pin axis CPU (?) chips between X and Y, and the problem stayed with the Y/M axis. So, I think that 40-pin chip is OK.

That means there's a problem with the drive board, as I suspected. My presumption is that the TG light indictes encoder failure, or a wiring fault related to the encoder, and NOT a problem with overcurrent/overvoltage/undervoltage/etc. Thus, the problem could be with the circuits that handle the encoder, or with the circuits that detect encoder error.

Now, I'm going to continue to trace the encoder circuits through the board, unless anyone has another idea (yeah, just send it out to be rebuilt - that's like declaring defeat!). I've got the TDS2014 warmed up.

Thanks for all your help! I surely appreciate it!

[fasto]

Well, I looked over the drive's board carefully and didn't see any obvious signs of bad components. I will say that the designers seem to have done a few things I would have avoided, like leaving unused logic gates with floating inputs.
Some person or persons unknown have been in the board before, evidently trying to repair this same, or a very similar, issue. They weilded their soldering iron more like a plumber would, though.

I did figure out a few things. The five lines that Hurco calls error flags or something like that are actually the 4 bits of the second encoder that the drive uses (1,2,4,8 not the A/B/Z for the control) that are optically protected, and a 24V line.
The error signals are logically OR'd using 7406 open collector inverters. I reverse engineered the Low Voltage error detector which shuts down all three servo sections.
I also traced out the path of the 1,2,4,8 encoder signals to the PWM generator IC's. I've got more work to do to understand the rest of the TTL logic, and how the drive recognizes the need for a TG error.

I put the drive board back on the power section, left the S10M jumper set to the bottom pins, and fired up the machine. It can't run away, the servo motors are cabled but the cogged belts are not installed.

The control had been reporting "Servo Fault Z Axis" (even though that axis seemed OK). With the S10M jumper on the bottom, the control didn't show any error messages.
I did Power-Reset Servos-Start and there was a big klunk from the electrical cabinet, which I'm not sure about but might have been the contactors in the servo drive (it might have also been an explosion, but I didn't smell any electronics smoke). When I looked in the cabinet, the TG-L and TG-N lights were on and another light, OC perhaps? I shut the main power off right away and forgot to write down the third light. With some luck (!) I didn't damage anything more than it's already damaged.

I will need to keep investigating, tomorrow.

[judleroy]

I have a bmc30 so I can say that when you reset servos and hit start there is always a clunk from the cabinet. I beleive this is just the contactors or relays enabling power to the drives and servos. I don't think you hurt anything. I can't help with any of your other problems as i am at a loss with electronics. The good news to you is that Bloke is the one giving you advice. As of now every problem with this machine posted on the zone by me has been resolved through his advice. Some good advice would be to check your home/limit switches to see if any of them are stuck in the depressed position. Remove and reseat all your wiring connections. Also making sure you use the static wristband remove the boards in the pc case clean wipe down the pin connectors and reseat them as well. There should be 3 or 4 rows off jumpers above the pc box, if so check that all the jumpers are seated well. These just press in. I don't know if this will help with your problems but it fixed most of mine and can't hurt(If the machine was recently moved many of these items could have become lose during transport).Good Luck!
Judleroy

[judleroy]

By wiring connections I mean the pc harnesses in the control box not every wire in the machine. Sorry if that sounds confusing.

[fasto]

Hi judleroy, thanks for the advice. That's what most folks who have moved machines say to do.

Since I design & manufacture PCB's I went a step further and ran all the control's pcb's through my PCB washer - you wouldn't believe how dirty they were, and neither Intel nor Hurco conformally coat their PCB's. There was about 2 fluid ounces of fine swarf in the bottom of the PCB washer at the finish.

I also spent a few hours and rang out all the wiring in the machine. My first job out of college was doing field service for a company that repaired control systems on cargo ships, and I know the mayhem that a loose wire or bad connection can cause. I don't really like the "push-in" terminal blocks that Hurco used, we always used either Weidmuller or Phoenix Contact screw down blocks.

I expected some problems with the machine, but I expected them with the control side, or the wiring, given the complexity of the 2-axis drive boards (each axis has its own 8031 CPU) and the personality board. I wasn't expecting the servo drive troubles. I don't think the Fanuc servo machines were as popular as the other servo systems, so there's a lot less people who have repaired the Fanuc drives. Also, Fanuc isn't really very forthcoming with the info about the drives, etc.

I really do appreciate the help that Bloke has provided; I was hoping that he'd take an interest in getting another machine back in operation! I also read through the entire Hurco forum here, every post except some that clearly weren't relevant. It has been a real gold mine of information.

Regards,
Aaron

[bloke]

Righty, here's the pins for the Fanuc encoder.
Honda plug._____Amphenol plug._____Signal.
1,2 & 3_________N & T_____________0V
4,5 & 6_________J & K_____________5V
8______________R________________O/HEAT 1
9______________S________________O/HEAT 2
10_____________M________________C8 (commutation binary)
11_____________L________________ C4 (commutation binary)
12_____________P________________C2 (commutation binary)
13_____________C________________C1 (commutation binary)
14_____________F________________PCZ (REF. PULSE)
16_____________A________________PCA (A PHASE)
18_____________B________________PCB (B PHASE)
20_____________H________________SIG. GND (connect to shield)
15_____________G________________*PCZ (REF. PULSE INVERSE)
17_____________D________________*PCA (A PHASE INVERSE)
19_____________E________________*PCB (B PHASE INVERSE)

[fasto]

Excellent, thanks!
Earlier you posted info about the S10[L|M|N] jumper that disabled error detection for each drive. Have you any info on the multitude of other jumpers on the drive?
Many thanks,
Aaron

[bloke]

I have a complete manual for the drive. It'll take a while to type them in but I'll put the other jumper functions up shortly.
Cliff.