Fanuc Analog AC spindle drive pulse generator circuit?
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    Default Fanuc Analog AC spindle drive pulse generator circuit?

    I have an 80's Kitamura 300mm pocket HMC with an old Fanuc 6 control. The thing runs pretty good, but recently the spindle will start and then alarm out. I got alarm 2 on the spindle drive "Speed is deviated from the command value due to overload and others"

    I followed the Fanuc spindle drive manual troubleshooting and I have something going on with the spindle pulse generator or the drive top board. Need some help.

    There are two pairs of signal wires from the spindle pulse generator that should each make a sine wave of a couple volts. Check. Got that at the test pins on the drive. But then the manual says to scope Check pins 7 and 8 and I should see a nice clean .5 to 4.5V 50% square wave. I get that signal on one pin, but on the other I get no signal. I tried adjusting R18 and R19 that the manual says influence that square wave, but no change.

    Anyone have a suggestion for components to check/test before I play musical top boards?

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    My schematic shows that pins 7 and 8 are the outputs of a quad comparator (LM339) at location MG7. The inputs to the comparator are the outputs of a dual op amp (LM1458) at location MF3. Seems like a channel of one of those chips is probably bad.

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    Thanks a ton! Digikey order placed, will update later this week.

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    Quote Originally Posted by Garwood View Post
    Thanks a ton! Digikey order placed, will update later this week.

    the spindle must be rotating to generate the wave.
    The adjustments are touchy. If you bork one of them and can no longer run it slow via MDI. A helper can rotate it by hand while you get it back closer.

    this is relevant to my interests as I had to adjust mine a year or two ago. Then again in October of this year out of the blue I had to do it again. Could the pulse generator on the motor get weak?

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    Quote Originally Posted by GENERALDISARRAY View Post
    .....Could the pulse generator on the motor get weak?
    Easy enough to check. Scope test pins 3 and 4 to 0V. Should get a wave form P-P at .35-.5V. DC mean voltage at ~2.5V. Frequency based on speed (helper turning spindle or motor by hand). If you do not get this signal level, then pulse generator pickup may be bad, out of adjustment, or maybe a bad cable.

    If the waveform is good at pins 3 and 4, but bad at 7 and 8 despite adjusting RV18 and RV19 then the op amp or the comparator may be bad. In the case of no signal on either pin 7 or 8 then in addition to the op amp and comparator there could be a problem with one of several resistors, several capacitors, or a couple diodes.

    If either of you want to see the circuit, PM me with your e-mail address. I'll send a pic of the schematic page in a reply.

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    Quote Originally Posted by GENERALDISARRAY View Post
    the spindle must be rotating to generate the wave.
    The adjustments are touchy. If you bork one of them and can no longer run it slow via MDI. A helper can rotate it by hand while you get it back closer.

    this is relevant to my interests as I had to adjust mine a year or two ago. Then again in October of this year out of the blue I had to do it again. Could the pulse generator on the motor get weak?
    I use a little two channel USB scope made for a laptop. I hooked the probes to the pins and had the screen setting on the table so I could see it while turning the spindle. The USB scopes work pretty good for machine repair. They're simple and just the right size to get into tight places and if you accidently drop it into a coolant sump you can buy another for $50 and not cry over it.

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    Quote Originally Posted by Garwood View Post
    I use a little two channel USB scope made for a laptop. I hooked the probes to the pins and had the screen setting on the table so I could see it while turning the spindle. The USB scopes work pretty good for machine repair. They're simple and just the right size to get into tight places and if you accidently drop it into a coolant sump you can buy another for $50 and not cry over it.
    Good thinking, might even SURVIVE immersion, actually.

    But throw-in a recycled or over-age in grade LAPTOP for that sort of general handiness as well. They are seldom as rugged.

    Otherwise, I'd rather risk my cheap Rigol than my costlier laptop!


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    Quote Originally Posted by thermite View Post
    Good thinking, might even SURVIVE immersion, actually.

    But throw-in a recycled or over-age in grade LAPTOP for that sort of general handiness as well. They are seldom as rugged.

    Otherwise, I'd rather risk my cheap Rigol than my costlier laptop!

    I have a few cheap old laptops with serial ports I use for shop and automotive stuff. The laptop is pretty disposable. It's just the time to reload all the software when one dies.

    I've had pretty good luck though. Dropped a lot of stuff, but most have faired OK. I've fried a Fluke DMM testing some higher DC voltage. I killed my first O-scope, a big old tube Tektronix by not having the right probes. I've run over a couple smart phones when they fell out of my pocket on the forklift and I dropped my old wormdrive skilsaw from 26 feet and scattered it. Have yet to kill a laptop that couldn't be fixed with new batteries.

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    Quote Originally Posted by Garwood View Post
    I have a few cheap old laptops with serial ports I use for shop and automotive stuff. The laptop is pretty disposable. It's just the time to reload all the software when one dies.
    Aye. Usta bug me with OS/2. Then Slackware. Then FreeBSD "make build world".

    OpenBSD, binary releases?

    About five minutes from a cold start, new storage device. Upgrades are faster if partitioning is already "there".

    I'd guess it is actually an "accidental" byproduct of a deeply reviewed high-security targeted OS to have near-zero "bloat" nor even the usual half-useful overheads left aboard by now.

    Gotten sore lean, mean, and LAZY in me dotage.


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    Quote Originally Posted by thermite View Post
    Aye. Usta bug me with OS/2. Then Slackware. Then FreeBSD "make build world".

    OpenBSD, binary releases?

    About five minutes from a cold start, new storage device. Upgrades are faster if partitioning is already "there".

    I'd guess it is actually an "accidental" byproduct of a deeply reviewed high-security targeted OS to have near-zero "bloat" nor even the usual half-useful overheads left aboard by now.

    Gotten sore lean, mean, and LAZY in me dotage.

    I don't know what any of that means. I really don't know much about computers. I kinda just figure out what I need to know to accomplish the task at hand. If I sounded like I knew what I was talking about I apologize.

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    Quote Originally Posted by Garwood View Post
    I don't know what any of that means. I really don't know much about computers. I kinda just figure out what I need to know to accomplish the task at hand. If I sounded like I knew what I was talking about I apologize.
    Nah. You know what you need to know well-enough.

    Bill Gates - both parents LAWSTERS, if you were not aware - just chose to build a pan-humankind "gullibility and sloth" detector test instead of a 'puter operating system.

    Worked well into "standard" human traits never in short supply. "Take the EASY road."

    Made him wealthy, spawned whole industries, lazy spooks and hungry criminals included.

    Yah don't have to be stoopid to pass his test. Even whip-smart ain't immune.
    Just pre-occupied with more important things to do with yer life.

    Wizards are just folks who are ornerier about that sort of "test". More about being contrarian than "smart", that is.

    Better part of 40 years, we had to work HARDER to not use the "easy but shitty"

    It finally came good. Now we don't have to hardly work at all.

    So much garbidge in a WinWOES install, I doubt you'd get it under five wall-clock minutes if yah "dd"ed a solid-state RAID 1 mirror image of it.

    We set it up with Win NT or 2K for HKG's Finance industry, we'd typically strip-out over seventy THOUSAND files as well as entire sub-systems. Clever guy in Oz pioneered that, "98 lite" onward. We just expanded on it.

    Result didn't need reboot between MB upgrades.

    About once a year.

    Fans & such get clogged to the point of overheat awfully fast in a crowded place with dirty air like HKG. Or Manhattan, NYC. New Mb & HDD swap was faster, cheaoer, better than cleaning, what with the high cost of labour. Stuff was at less risk of going obsolete or failing "mission critical' line-of-business applications unexpectedly as well.

    Most places didn't NEED but 2 or 3 Win-specific apps. A separate box - Mac Mini, or now and then Linux - did the email and networking "outside dirty cesspool of a world" stuff with less risk to a bizness core value.

    Win's equivalent to a kernel weren't half bad, even that far back. Sean did a good bizness with a stripped-down "headless" version as didn't even run a local "Graphical User Interface" nor even own a display screen atall.

    Thank IBM and a guy who stole from DEC's VAX for that. By the time Gates & Co. lost the conflict, DEC was toast and MS was so rich the settlement wasn't even pocket-change.

    IBM could make more MONEY servicing an OS that was broken more days than not than supporting a far more stable one.

    And that's the "model". If Win ain't broke from neglect?
    MS will BREAK it a-purpose to keep the revenoo stream clocking new money.

    I did say both of "young Bill's" parents were lawsters?


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    WTH does any of this have to do with the 50/50 balance of the square ware speed reference signal for the Fanuc 6044 series Spindle drives?

    A valuable note for posterity, not mentioned before. The check pins and RV pots are underneath the orientation board. the board will pivot up to allow access. Hold it there with a piece of non-conducting string.

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    Quote Originally Posted by GENERALDISARRAY View Post
    WTH does any of this have to do with the 50/50 balance of the square ware speed reference signal for the Fanuc 6044 series Spindle drives?......
    Quite often the case when thermite notices a thread. I suspect alcohol and an old man's memories may have something to do with it. At least that's what causes me to ramble occasionally.

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    Quote Originally Posted by Vancbiker View Post
    Quite often the case when thermite notices a thread. I suspect alcohol and an old man's memories may have something to do with it. At least that's what causes me to ramble occasionally.
    I must be more fuel efficient? I manage the whole schtick without the alcohol.


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    Update:

    I ordered 10 each of the IC's Vancbiker recommended and then stalled for a few weeks while working on other stuff. Vancbiker was also very generous to email me the schematic for this circuit which is not in the drive maintenance manual. I swapped out MF3 and MG7 with no change in symptoms. I tried adjusting RV18 and RV19 all over the place while watching the scope and turning the spindle by hand. I ended up cranking RV18 and RV19 way too high and destroying MF3, MG7 again. I replaced them and still no change. Basically my A phase signal was just low all the time. So I stared down the schematic and tested diodes and resistors on the board and all seemed well.

    I decided after looking at the schematic for awhile that MF6 has something to do with the signals and it's the same chip as MF3 so I popped it out and soldered in a new chip and then I got something- A phase was stuck high when I re-installed the board. I screwed around adjusting RV18 and RV19 and I could get the signal on check pins 7 and 8 to be either stuck high or stuck low, but not a nice square waveform like it's supposed to be.

    It's not easy to adjust the pots in the control cabinet, watch the scope and turn the spindle by hand so I rigged up a cordless drill on a toolholder and ziptied the trigger on about 10 RPM. After that it was very straightforward to watch the signal on pins 7 and 8 and adjust RV18 and 19. I got my squarewaves and the spindle is warming up right now.

    I think there might be something else going on like bad capicitors or interference somewhere because RV18 and RV19 are super sensitive. They go from a volt or 2 and jump aggressively up to 8-10 volts. For now it seems to be working again.

    Hopefully this helps someone else down the road.

    EDIT: Something else I just remembered- When I was scoping check pins 3 and 4 (the input sinewave signal) the A phase signal was much weaker than the B phase like something was pulling it down. That was one of the other things that led me to believe it was MF6 that was part of the problem.

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