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IndustryArena Forum > MetalWorking Machines > Okuma > Okuma LB15. CRPB board type?
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  1. #1
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    Okuma LB15. CRPB board type?

    Hello,
    I have an LB15 lathe with a faulty CRPB board (confirmed) The part number of the bad board is 1911-164 2

    I found a board online, looks identical in layout the part number is close 1911-164 1. Im told it was from a MC4 mill. Would it be compatible with my lathe?

    thank you.

  2. #2
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    Re: Okuma LB15. CRPB board type?

    Yes of course
    "Imagination is more important than knowledge."

  3. #3
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    Re: Okuma LB15. CRPB board type?

    Quote Originally Posted by kurmay View Post
    Yes of course
    Kurmay, thankyou!

    So you are saying if the board came from a MC4 Okuma milling machine It can still work in the LB15 lathe? It is literally the same looking board. the components and layout are the same just the part number has a '1' where as my board has a '2'. ie 11

    I was not sure if the board from the milling would be different for the extra axis and so have different graphics requirements X Y Z etc?

    Does the graphics seen on the monitor not come from this CRPB-II board?

    See below the two boards
    Attached Thumbnails Attached Thumbnails CRPB Mill crop.jpg  

  4. #4
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    Re: Okuma LB15. CRPB board type?

    A 1911-1641 is a CRPII GR color graphic board w/ROM, a 1911-1642 is a CRPII GR-EX1, wROM (the EX is for graphic export), so they are slightly different in that aspect, but are interchangeable, as Kurmay has stated. If you had a 1640 board, or 1692 board, then not the same. If you want a 1641 board with a warranty, we have 2 available.

  5. #5
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    Re: Okuma LB15. CRPB board type?

    Board arrived worked fine.

    Next problem 110 alarm SDU 1.
    Changed out with spare unit same alarm
    No LEDS on drive unit ?
    Any ideas

  6. #6
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    Re: Okuma LB15. CRPB board type?

    Check incoming power, if all good (between phases and each phase to ground), then power it down and check fuses. Depending on what drive you have, they are located in different spots; there are some on the control board and more in the base unit (if I knew the model of the drive I could tell you where and which ones are relevant). In any event, if they are all good, then you can disconnect the connectors on the top board and just turn on the main disconnect on the machine. If the drive still has no lights, then the drive is bad (with the connectors disconnected and the incoming three phase good, there is nothing external that can cause this).

  7. #7
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    Re: Okuma LB15. FANUC SDU 110-Alarm A SDU 1 (no leds lit)

    Hi cncts, great info.
    I did check the fuses for the fat mains in, these are OK
    BUT
    I did find a glass fuse (5A) blown behind the board R and S pictured. Replaced the fuse, as soon as switch the mains on POP she blows imediatley.
    The SDU is a Fanuc, the drive unit came from a working machine, 100% confirmed ok (when pulled out). I find it a little too coincidental that bothunits could have the same issue, ie no LED and both share the same alarm. Especially when both were known to be working.

  8. #8
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    UPDATE blown fuse on Fanuc SDU (LB15)

    Ok I did find a blown fuse, its was one of the small glass fuses on behind the main board. The one marked S in this pic.
    I replace the fuse then either R or S fuse blows.
    Any ideas where the short might be?

    Also with both fuses removed. the top two wires have continuity across each other, Not sure if they should? Even with the capacitor removed still show continuity

  9. #9
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    Re: UPDATE blown fuse on Fanuc SDU (LB15)

    OK, so Fanuc drive is a little different, but not much. Yes, odd to have two drives with same issue (the alarm #110 is not uncommon - it is the same alarm for almost every spindle drive fault on these older machines; what it really means is "go look at the spindle drive and diagnose the LEDs (or lack of)". In any event, you found a blown fuse, I assume the other drive has the same blown fuse and if so, then most likely something external is causing that (trace the wires from those fuses, to see if they go out to the fan on the motor, that would be the most likely culprit - it is probably bad. I have to check a schematic, but I believe the fan on the spindle drive also runs off those same fuses, but again, if both drives have the same blown fuse that would mean both drives have bad internal fans as well. Check your other drive to see if same fuse is blown.

  10. #10
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    Re: Okuma LB15. CRPB board type?

    cncts11, very good.... I was thinking the same, so before a left the shop, I disconnected all the large wires that connect to the lower section of the drive to the spindle motor, I left the big fat input mains power wires (3 phase) connected. So I basically disconnected the heavy out put wires to the that head off to the motor. There are three of these heavy wires tagged U1 V1 W1 and then two lighter wires right next to these, marked U and V (perhaps fan output). These were ALL disconnected and I left them h hanging for an isolation test, Glass fuses replaced. Short gone!!!!

    Machine now starts and moves on all axis (first time in 10 years, I did pre lube the ways and cycle the ball screws priorZ). The SDU short has now gone! and the green status LED on the Fanuc SDU is now lit and shows a normal condition.

    Now to sort the spindle.

    The next task is to figure where the short is. Ill obviously check the motor and as you said the fan on the motor, fingers crossed.
    I'll also check to see if the other SDU (original) has the same blown fuse. Im sure it will have. I will confirm.

    PS: The fans on he SDU are whirling away fine. I recall this from yesterday after disconnecting the short, So its not the cooling fans in the SDU these are fine, with the SDU alive.

    Many Thanks.
    Attached Thumbnails Attached Thumbnails Fat motor wires SHORT.jpg  

  11. #11
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    Re: Okuma LB15. CRPB board type?

    Well, it pretty much has to be the spindle motor fan...those main wires (U,V,W) for the spindle motor definitely do not go through that small glass fuse. We sell the spindle motor fans, need to know which one you have. BTW, your motor is probably mounted in an inverted position (the fan is in towards the center of the machine). If so, then you should have a "tray" that can slide out and allow you to access the fan a little easier (it doesn't look like a try, but look for a couple large bolts that are on the edge of the machine frame that you can remove).

  12. #12
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    Re: Okuma LB15. CRPB board type?

    Thanks! Yep its where im heading next. Could I do a quick test and only hook up the 3 fat UVW output motor wires? and leave the two U and V thin wires off, as Im assuming the light wires U and V are where the short is ie the spindle motor cooling fan?

  13. #13
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    UPDATE PROBLEM FIXED

    UPDATE:
    So I did indeed reconnect the motor wires V1 U1 W1 and see what happened, sure enough the short gone, and the spindle runs YEAH!

    But after a few spindle stops from say 1000 rpm. The SDU would alarm, see picture for LEDs lit. Happened a few times, fuses are ok, restart machine then ok again for a few minutes then again on a spindle stop and on spindle braking....110 Alarm would trip....Hmmmm
    So I reconnected the surge capacitor for terminals 5 and 6 on T1 block (see pic), I also switched the voltage to 220V. And pulled all the circuit board push plugs then re plugged. Somewhere in a all that the new alarm went away.

    I've been running the machine all day, no issues so far.
    I will have to take a look at the spindle motor cooling fan as its not connected (has a suspected short) and will need to be fixed soon. But for now the small one off parts Im running wont push the MC in the least.

    Thank you to all my CNC brothers that offered their help.

  14. #14
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    Almost but not quite!

    This morning I fired up the machine. Spindle ran for a few seconds and then got 110 Alarm SDU 1. Restarted the machine and same again.

    Checked the Fanuc drive and It has LED 2 lit which going by the FANUC books says "Excessive servo error".

    Restarted machine this time let sit idle for 15 minutes or so. Then after 15 mins ran the spindle at 500 rpm, Alarm wont come back now. Machine is running ok for now.

    From cold start any ideas of what may be causing this "Excessive servo error" on the Fanuc SDU?

    Im tempted to install the original spindle drive as Its likely just a fuse, and this drive was possibly tuned to this machine?

    Cheers, Paul.

  15. #15
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    Re: Okuma LB15. CRPB board type?

    This morning I fired up the machine. Spindle ran for a few seconds and then got 110 Alarm SDU 1. Restarted the machine and same again.

    Checked the Fanuc drive and It has LED 2 lit which going by the FANUC books says "Excessive servo error".

    Restarted machine this time let sit idle for 15 minutes or so. Then after 15 mins ran the spindle at 500 rpm, Alarm wont come back now. Machine is running ok for now.

    From cold start any ideas of what may be causing this "Excessive servo error" on the Fanuc SDU?

    Im tempted to install the original spindle drive as Its likely just a fuse, and this drive was possibly tuned to this machine?

    Cheers, Paul.

  16. #16
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    Re: Okuma LB15. CRPB board type?

    my manual for an Lb-10 with fanuc drive has the causes listed as
    1. overload - check load meter- examine cutting conditions.
    2. poor contact connector - check CN2
    3. malfuncton of torque limiter -confirm meter reading- replace circuit board
    4 failed speed feedback signal - replace printed circuit board (not sure if this is the spindle encoder or the servo encoder. the wave form from the spindle encoder is really easy to check with a oscilloscope)

  17. #17
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    Landslide1
    Thanks, machine (LB15) was sort of hanging in last few days, but Im getting more and more issues with an alarm on the Fanuc SDU "Current overload" alarm. Ive been watching the AMP meter on the control panel and sure enough as soon as I increase the RPM to say 1000 then the meter creeps into the red and then the alarm happens.
    The motor spins freely by hand and my gut feeling is the motor is ok. Certainly mechanically ok.

    Any ideas, on the "over current" issue?
    Last edited by rotec; 12-02-2018 at 11:06 PM.

  18. #18
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    UPDATE:

    Since swapping out the SDU the machines spindle now turns but very erratically and while spinning is in the red % as far as load is concerned even thought its not cutting.
    Then withing just a few seconds say 15-30 the SDU will alarm with an over load message.

    From reading around here, It seems it could be a tuning issue, or the tach sensor on the motor.

  19. #19
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    Re: Okuma LB15. CRPB board type?

    UPDATE:
    Spindle drive issue solved. After installing a replacement used SDU it ran erratic and then alarmed but at least it moved! I then did an experiment and put the old SDU back in and replaced the main circuit board from the new used unit to the original. Works fine at least for now.

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