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  1. #1
    Join Date
    May 2014
    Posts
    6

    Unhappy 24 VDC NC vanished

    Hello, I purchased an 89 MV JUNIOR 10 MD control....Machine is a real cherry except for.... Main Board shows 1, Replaced the power supply with a known good one, no help.. BTW all fuses are good thru the machine. Replaced the DI/DO board with a known good one. No help. Replaced the I/O board inside the operators panel No help. Checked all Honda connectors for good connections.
    Machine has no 24 NC voltage to any of the terminals, also the operators panel below the CRT and MDI keys is lifeless. + 5 volt is good. Reset button and all keys below example homing, Rotary function switch, MDI, EDIT etc. are down. All functions such as viewing programs, ladder, changing parameters viewing position....all soft keys operate.
    It may be a cherry because it hasn't run in 15 years, we pulled all cover and it was full of muti color plastic chips.
    The P24/N24 board seem to be OK. This machine has a spindle cooler, and spindle mist lube.....Both are up and show no problems.
    OT switches do shut down the machine. Operator E-Stop drops the control out.
    I was told the machine had a 24 volt problem when I bought it. The machine has Absolute encoders......When firing up you end up with an OT32 needs homing alarm for all axis'. You can't get the machine MRDY signal to enable the servo's so I can't clear that one.
    We have owned something like 8 juniors over the years. 3 early ones with linear guides on Z...This one is Box way and full enclosure We still have 2 later ones making good parts. This one is for my semi-retirement home shop. Started sharpening Drill Bits for my dad when I was 6 or 7 and I'm still trying to know it all 58 years later.
    I've pulled all the 24NC wires off every switch I could get to hoping to find the culprit.
    Apparently the previous owner had Fanuc take a quick look and they seemed to think a proximity or limit is going to ground, It blows no fuses. I'm leaning to an ESTP caused possibly when a factory pallet changer was removed and not bypassed. However I was told the machine ran fine after the pallet changer and pallet receiver were removed. I know it's a long post but I'm trying to cover all the bases. I'm kind of out in the boonies so bringing in a Fanuc guy is big Bucks. I hate to get beat but this one has me. Rich

  2. #2
    Join Date
    Feb 2009
    Posts
    6028

    Re: 24 VDC NC vanished

    Sounds like the power supply next to the CRT, which one did you change?

    Sent from my G-Tab Quantum using Tapatalk

  3. #3
    Join Date
    May 2014
    Posts
    6

    Re: 24 VDC NC vanished

    Big Black on the main board

  4. #4
    Join Date
    May 2014
    Posts
    6

    Re: 24 VDC NC vanished

    I forgot to say thanks, I did swap the Mori I/O next to the CRT. I didn't know there was a PS next to the monitor.
    I'll see if I can locate it and swap it out. I sure hope your correct.
    When the machine does come up it jumps to Emergency Stop. Rest button is disabled and like I mentioned before all the function keys also.
    Thanks again to under thethetire!

  5. #5
    Join Date
    Aug 2011
    Posts
    2517

    Re: 24 VDC NC vanished

    the 24V power supply controls/powers the operator panel so a dead panel means almost certainly a dead 24V power supply.

  6. #6
    Join Date
    May 2014
    Posts
    6

    Re: 24 VDC NC vanished

    Thanks for your post fordav11....I pulled a power unit from a lathe that's up and making parts....The 24NC power is still zero.....On this Junior there is a P24/N24 power supply-it functions. Also the Power Unit that plugs into the main (mother board). In the operators unit with the CRT the only board in there is a Mori I/O board. I can't tell for sure but it's either powered from the DI/DO board or the main board. It checks good for 5volts but no good for 24 volts on the test pins. I would agree that it seems the power unit would be out or at a minimum a blown fuse. I wish that were the case. I have an 89 Mori M-300 that had some parts in common, this machine was de commissioned after I returned from hospital, Somehow the leadman managed to break a main casting in the toolchanger and locked up and broke the pallet indexing. This was a metric machine and the pallets would work on our SAE partners but not the other way around. That was a bad year. BTW I hear Agent Orange can do funny things to your body. Sorry about getting off topic.....On P24 to earth I get something like 155 OHMS that seems about right....On 24NC to earth I get 0 OHMS.....Actually .01 OHMS Seems like a dead short. The partners have an additional 24 volt supply. I believe those are opto isolated Rich

  7. #7
    Join Date
    Feb 2009
    Posts
    6028

    Re: 24 VDC NC vanished

    I'd start by pulling all the io cables out and check 24nc to ground, hopefully see a change, then plug one in at a time. Should be a bunch of Honda connectors

    Sent from my G-Tab Quantum using Tapatalk

  8. #8
    Join Date
    May 2014
    Posts
    6

    Re: 24 VDC NC vanished

    Hello all, I pulled all the Honda connectors also the NC connectors that would still allow me to bring the machine part way up. Nothing. I hung a separate 24VDC power supply on to a terminal strip. NC 24 & 0V. I found a prox switch that pulled that supply down. Replaced the switch, that eliminated the (a) short. Fired the machine up with that supply hot. I figured it would be a bit risky. Machine still exhibits the same symptoms (no lower operator panel function MDI, EDIT, RUN, HOMING.....+ all the leds are still out. I have 5VDC + 24 VDC on NC24/0V at every strip, contactor, test point I could find . I unhooked the separate P/S and I have about .4 volts on the NC24 now. And I still have 5VDC at all check points, including the MPG. Machine is still dead. I rechecked the spindle lube and cooler for problems +float level switches on the tool unclamp and spindle lube. Replaced the main P/S on the Mother board. No help and no findings. I'm about out of stuff to try except start throwing money at it. My thinking is that even at an estp condition there should still be 24NC somewhere. I would think that the NC ready relays would not pull in therefore no MRDY. Do you know if the 24NC voltage exits to the system thru the main board>thru MDI board, or DI/DO....I'm not that proficient at reading the electrical drawings, but it appears that the 24NC is powered partly thru CN1 Honda........first stop is either the crt or the spindle drive. Spindle drive looks up and no alarms all 5 spindle drive leds are displaying 0. However the NC24
    is distributed it is stopped before it can be dispersed to any terminal strip, icebox estp relay, contactor or any other point that I can find and measure. It's making me crazy......I need some breadcrumbs to follow because I
    am lost.

  9. #9
    Join Date
    Feb 2009
    Posts
    6028

    Re: 24 VDC NC vanished

    Can you scan prints to PDF and email? Some of those old machines took ac voltage through a small bridge rectifier to produce 24vdc. Not sure what set up you have. Lower panel should light up regardless of estop condition. I've run in to similar problems on early MV65's

    Sent from my G-Tab Quantum using Tapatalk

  10. #10
    Join Date
    Feb 2011
    Posts
    640

    Re: 24 VDC NC vanished

    not saying its right/use at own risk... all our asian machines with external power supplies we have removed. pull the extra supply, jump it into the Fanuc side. problem we often ran into was the extra supply was linear type, and a short wont blow a fuse, just sinks half the machines power to near zero. unless the machine has a lot of 24 volt solenoids, the Fanuc supply can usually carry it easily. Fanuc supplies are switchers, if they get shorted they pop a fuse...easier to know theres a problem, we had one machine years ago that only lost some solenoid power and limit switch commons for homing, if it got a short it would hard overtravel when homed, other than that no indication of problems... we found it easier to just run on one.


    anyways, back to existing situation- are you watching supply when you hit the machine ready button? *if* the extra supply is a linear type, it might be fine until the button is pushed. something as simple as a shorted PB light socket can pull it to zero...

    Ive got a MVJR book at work somewhere, ours didnt have pallet changers and were 10M-A though... remember the ladder was 298 pages w/pascal for ATC manual operation screen text only...rewrote it from scratch in 30 pages with no pascal, looked same to operators except text for ATC was small 'operator message' size font...ours also had a weird air/hyd booster for drawbar pressure that often needed serviced- always thought it odd they didnt put a off the shelf part in there instead of all the custom castings and such... nice little machines though- I'd still consider losing the 2nd supply though if possible. good luck with it,
    Tim

  11. #11
    Join Date
    Feb 2013
    Posts
    151

    Re: 24 VDC NC vanished

    Nixman,

    Have you checked for power on the indicator light pins or the panel switches? If so do you see 24 volts? Could you take pictures of the cabinet and controller cards and post them? I have an 11m which is a step up from the 10m. On my machine, the 5 volt power rail that powers the mdi/crt board and the interface cards died, however, the 24 volt supply is still ok. I tore the whole machine apart trying to find the 5 volt source. Turned out that the power supply was between keypad and the Mdi board. A view of the mdi board:
    Attachment 237560
    The power supply that is hidden below the mdi board. This supply is the one that supplies the 24 volts to the switches and lights on the front panel. Well at least on an 11m.
    Click image for larger version. 

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    It is fused on all outputs.

  12. #12
    Join Date
    May 2014
    Posts
    6

    Re: 24 VDC NC vanished

    Hi Thanks I can take some pictures and post, been down with some old Army problems and haven't been able to work. About a week ago I found another short.....I was able to get the servo's up. Still don't have use of the operator keys so I can't zero return, mdi, etc. Also I can create PDF's. I finally got a few breadcrumbs, but it's not going to give up without a fight. On the machine ladder Diagnostics G0 bit 4 and 5 have to be 1....The short
    cleared up bit 4 X8.4.....The machine needs 4 & 5 to be high to allow the PC to come up. I'm pretty positive it's an NC problem and not a Fanuc. The machine seems to have been in some kind of corrosive environment. Some of the terminal strips are brittle as well as the Honda plug covers want to break on the spring retainers. Also by one of the fans the paint is a bit corroded thru. Other than that all the mechanicals look great. The boards look new. Also it looks like a previous owner used straight water for coolant. All that cleaned right up. The paint is very good except on the doors and the magazine cover. That's why I'm leaning towards a short. Also
    the spindle stop button and feed hold buttons were dead. They need to be in the NC position and send 24 volts down the line. Both were open. CJ I'll take a look at the MDI CRT. My MH 40 has an 11m so I'll open it up and look around. It's a full 4th. Thanks to all

  13. #13
    Join Date
    Feb 2011
    Posts
    640

    Re: 24 VDC NC vanished

    bet someone cleaned the control/connectors with simplegreen or naturalblue brand cleaners or similar... the stuff works great but turns vinyl/plastic to eggshells...ive begged them at work to quit buying that stuff and just use 409 or fantastik, it never hurt anything in all the years weve used those... simplegreen (especially if mixed strong) will harden and crack brand new 'membrane' style keyboards a day after cleaning, we've spent a fortune because guys wipe the membranes off with it... have seen the grey honda shells crumble from it, sometimes the plastic gets a chalky color on the surface too

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