Fixing a Scorbot ER4-PC

Fixing a Scorbot ER4-PC

{adinserter Internal_left}No electronics lab can go for long without a robot eventually making its way in. Well, in my lab there is approx a dozen. Most are Scorbots by Eshed Robotec (Intelitek, Depco and there may be other names under which they were sold) These robots are usually rather old and by the time you get them they have been through a couple of generations of middle school students. But they were built solid and many survived, even if in need of repair. This is what this post is about So, here is how the drama played out:

It took A WHILE to get this guy running. On homing attempt using ER2U controller it would generate Axis 5 homing error. For some reason assumed switched aren’t working. Re-checked all switch wiring – all good.

Checked homing using Controller-A homing procedure (it shows more info) – showed Axis 5 overload protection. Resettable fuse popped. Checked the motor itself – one of the windings is short. Opened motor – full of metal shavings. What the heck? Threw away (well, into reject bin. I never actually throw away anything electronic) the motor, took a replacement from a sacrificial ERIII. Replacement motor turned out to have a bend rotor axle. Tried to straighten. Sort of worked but makes funny noise, does not look like it will live long. Took another motor from an ERIII. At this point it became clear ERIII is going down – no way to find so many extra GM9413-F motors. Longer axle appears to be a custom order from Pittman. Price list is in $250 range. How would you like a single motor more expensive than the rest of the robot?

Anyways, back to repair: put a replacement motor back. Tried homing – same thing! A slight difference – Controller A no longer shows overload. Checked motor #4 reasoning that Axes 4 and 5 are actually moved by synced movement of both motors. Motor OK – runs from a 12V source just fine. Must be encoder then. Checked the wiring, all good. Cross-checked ER4U and ERVPlus wiring diagrams – they show opposite polarities for encoder outputs. What gives? Swapped wires on both encoders for just in case – still no go.

Went back to the docs, couple pages further they describe wiring on the 510 encoder PCB. Turns out they swapped wiring assignment twice between these two tables. Two negatives give a positive, in the end both pinouts are the same. Whew!   Removed 510 PCBs again to solder the wired back in the original order.  During soldering looked VERY closely at the axis 5 510 encoder PCB – one of the pins of one transistor is not soldered! Smacked myself on the head (gently), soldered the pin , closed the encoders and gave it a run.
It homed!!!

Searching for a problem – approx 10 man hours. Fixing the problem – instant!

Oh, BTW, should I mention the robot was sold to me as “working, excellent condotion”?

27 Responses to “Fixing a Scorbot ER4-PC”

  • Terry Briley:

    I have the same ER4 Scorbot from ESHED. Bought from DEPCO.
    The control box is dead. Has sit there for acouple years now.
    I asked DEPCO and ESHED $100.00 an hour just to look at it, plus shipping.
    DEPCO tried to sell another one.
    Is there a way to switch over to stepping motors, so I can use a GECKO driver board?
    Or do you have any suggestions on the control box.
    I opened up and checked the power supply, but I don’t have any schematics.


    • admin:

      Hi Terry,

      Sorry to hear about the controller. Well, I have fixed one ER2U (same as ER4U) from Depco not long ago and in my case it was 5V power supply circuit. They use ancient power supplies with 7805 regulators. They have very large 10,000 uF electrolytic capacitors at both in and out of the 7805. Mine had the one on the “in” side shortened. I also heard that happens a lot from fellow Scorbot owners. In my case I just replaced the cap and the whole thing came alive and started working. I also did not have schematics per se but this type of problem was rather easy to trace. The controller needs 12V and 5V and the 5V was missing.

      Your problem can be more complicated but do you have ANY lights on your controller at all? From what I could gather playing with these for the past year or so, the robots very frequently overload the power supplies by bumping into obstacles and if the fuses don’t give out, more important parts inside do. In addition to that, most Scorbots available from eBay and such are 10+ years old and electrolytic capacitors don’t age well. Some people suggest replacing them right away upon getting an old Scorpower control box

      If the box is completely dead, you may be having one of those power supply issues.

      Post more details, maybe I can help.

  • George:

    Sorry if I’m hijacking this thread, but I have an ER4U robot with an ER4PC controller. My problem is that my PC will not recognize the ER4PC ISA controller card no matter what I do with addresses or IRQ’s. Any ideas?

    • admin:

      Hi George,

      No, that’s quite all right, it’s very relevant to the post. I am sorry but I won’t be of much help. In the end I was never able to source the ISA card (the PC Servo Control Card ). The robot you see here is, in fact, an ER4PC and it did come with Scorpower PC controller but the said card was missing and I had to find the USB version of the controller to be able to see it move.
      That said, I hope you have the Controller-PC manual (check on the Robotics Resources page if you don’t) and it has a section on Resolving Address Conflicts. It says:

      By default, the PC servo control card uses eight consecutive addresses, 0300-0308, and interrupt 7. Other devices may occupy the address space used by the servo control card, causing the software to report an address error or to perform unreliably.

      Maybe there is a device in your PC that’s already using this address of IRQ 7 ?

      it also says

      If IRQ 7 is in use (which is likely if a printer is connected to your PC), check whether
      IRQ 5 or IRQ 3 is available. (No other options will be possible.)

      I would add that you can also just disable the printer in your PC’s BIOS if you don’t have to print from that PC or if the printer can be attached via Ethernet or USB as most modern printers are.

      Sorry I can’t be of more help because of not actually having the card. But if you don’t have the manual, be sure to get a copy.

      If you’re successful in making it run, I would be glad to learn what did you do to fix it.

      Good luck!

  • George:

    I have not been able to fix it. I’ve tried many combinations of addresses and IRQ’s. The last one I settled with is 280 and IRQ 5. Device Manager shows both of those open. I’m stumped and am now wondering if the card is bad.

    • HOlly:

      Hi George I had the same problem there are two jumpers on the inside of the controller connected to the computer board where the controller hooks up to the robot. In order for the computer to recognize the controller. The two jumpers are next to each other the first jumper must be on pin 2&3 and the second jumper must be on pin 1&2. There is a video on you tube. I think I found under scorbot pin

  • admin:

    Hi George,
    Sorry to hear it’s still not working. Like I said, please keep in mind that having no card myself I am not much of a help. But I’m thinking about how I would troubleshoot that and maybe in this back and forth some proper questions would come up?

    Anyways, you did not mention if you’ve actually attempted to start the proper version of Scorbase Pro software (version for ER4USB is different from ER4PC) and looked at the card in there rather than in Windows Device Manager. It has been a few years since I used Windows extensively but I have a feeling the Device Manager may not show a card of unknown type, although it would probably show up as one of those question-mark devices… In any case, this is how the manual says you should lookup the proper jumper settings – the Scorbase software talks to the card directly and reads the jumpers, then shows it on a screen.

    If it comes up in neither manager nor Scorbase, then I would be tempted to think it’s defective. Even then, given that IRQ 3 and 5 are used by COM ports, it may not hurt to try and disable all those ports in BIOS and run Scorbase to see if the card showed up.

    If nothing works, Intelitek ( may be able to fix it for less than they ask for a refurbished card ($600)

  • George:

    This controller uses ER4PC, so I have started up the Scorbase Setup software to verify the card, and it fails the address check. I was using the Windows Device Manager to see if the card showed up at all but no dice.

    Intelitek may be my next step. If I go that route, I’ll probably try to get an ER4U controller and do away with the ISA card completely unless it is too expensive. If it is, I’ll try to get another ER4PC ISA card.

  • Martin:

    great site. i hope to contribute as soon as i have any interesting,
    up till now only questions

    I have my first depco scorebot.
    where can i download some software to play with it.

    • admin:

      Hi Martin,
      Congrats on your first Scrobot!
      For the software, you may want to check out the Files section of Yahoo’s Scorbot group. Look for ScorBase software. The version you need should correspond to the type of controller you have. The PC version (the one with PC Servo Card) needs version 3.7+, the USB version needs V4+

  • Jodi:

    I realize this post and questions are a bit old, but I was hoping someone out there may be able to help me. We were having trouble with our second axis and determined it was the motor, so we replaced it. It seemed to be working fine, however that axis just won’t move consistently anymore. For example, if a position it taught that involved that axis, it is about a half an inch different each time it is run to that position. That is, however, unless it is homed in between each and every single time that axis is used. Is there some sort of calibration or something that we are missing?

    • Hello Jody and thank you for stopping by!

      If I remember correctly, I had something similar on one of my ERIII arms. In my case though I don’t think the actual deviation was the same every time. It would arrive at a slightly different spot each time. It was caused by a slipping encoder disk (well, propeller rather if you have an ERIII) which I forgot to tighten on the motor’s axis. By the time it would catch up with the motor, it would have missed a few rotations.

      I don’t know if this is similar to what you have. Maybe you can post this question in our newly minted Robotics Forum where other people may be able to respond as well. Additionally, you will be able to post pictures which may help explaining the issue a bit further.

      Thanks again for stopping by !

  • Dave:

    I have been having trouble getting my ER4U to home. It gets stuck at axis 4 each time. I have tried to spin the disk on the side of the arm to realign the arm. The computer usually times out prior to homing the axis. How do I diagnose the problem? Do I have a bad limit switch, motor, encoder… Is there a location on the software to check what values the encoder should be reading? I am a beginner and not sure where to look. I do know that sending the unit for servicing is simply too expensive. Any suggestions?

    • Hello Dave, thank you for stopping by my site!

      Yes, there is a way to read the values off of the encoder. There is a menu item in the ScorBase software that does exactly that. I am not too sure you can enable that window before homing though – I’ll have to look in the lab tomorrow. In the meantime – when you say “gets stuck”, do you mean it does not move and just sits and waits or it gets into a position where it pulls on the gripper cables so much that cannot go any further? I’ve seen it both ways – which is yours?
      To better keep track of the questions and responses, please post in this thread in the forums I just started specifically for this issue (which comes up quite often):
      Scorbot Homing Issues
      Thanks again for stopping by!

  • Charlie Parker:

    I am looking at getting an ER2U up and running. Does anyone have a extra PC-CARD laying around? I have checked Depco and they do not have anymore and want to sale me the newer USB version. Can’t do that. Any suggestions on another way to make this thing work?
    Thanks for any help.

    • ER2U are cool robots! Have all the parts of the big(ger) ones but are way easier to handle. I’ve got one but, unfortunately, badly damaged. Anyway, regarding the PC servo card: I would not pursue that route. I also have a ER4PC that needs it but stopped looking for it long time ago. It not only runs about $600 but, most importantly, requires a PC with an ISA slot on the motherboard. It has been about 15 years since I’ve actually seen one. You can do with a USB-to-ISA adapter but then you need to purchase two highly specialized pieces of hardware, both not cheap.

      I would keep searching eBay until an ER4U or ER2U controller turns up (they are identical). Sometimes a broken one is being sold really cheap, and they are not difficult to repair – the first thing that breaks is the power source, and it’s a very primitive 90s era design. Usually replacing a dried up electrolytic capacitor or burnt 7805 voltage regulator chip does the trick.

      How much does Depco (or Intelitek for that matter) want for a new ER4U controller? They are almost always offered on eBay for ~$300 used, the trick is usually to find a cheaper one. Good luck!

  • Kunkmiester:

    Do you know what kind of encoders the motors use? Gecko and others make servo drivers, so if the encoder is right, you can make a LinuxCNC or EMC2 or ROS based controller for the robot. That would probably be the easiest solution to burned out drivers.

    • I think you are correct, LinuxCNC should be able to control it using a more widely available CNC servo drivers. In fact, I bought a bunch of DC servo drivers some time ago, but did not since have time to put this all together. The robots are using quadrature encoders. Crude ones (3 or 6 slots per rotation if I remember correctly, depending on the robot’s model), but should still be compatible with many DC servo drivers out there.
      At the same time, I did not feel like just throwing away the stock controller from that robot, hence my efforts to revive it and this post.

      Thank you for stopping by my blog!

  • enver:

    Hi Dear Fhrends.

    Last year my father take me one ER 4pc arm control box but hi didnt buy PC card, last week ı find it in internet and ı get it than today ı bought one old computer win 98 (se), I dowland program ER-4PU but what do you thinking , can I working with ER 4pu program or ı need orginal 4PC program.

    Thanks all

  • Will:

    I also aquired a scorbot 3 without a controller and in my spare time I have been developing a simple servo driver. If you do some more research online you can find many articles regarding diy’ing your own controllers for these old bots.

  • rodrigo:

    hello my name is rodrigo work with a scorbot er3 and my doubt is how you got the reading of the encoders the pcb board is the same pc 510

  • rodrigo:

    hola estoy trabajando con un scorbot er3 mi duda es:
    que circuito implementaste para leer los pulsos del encoder

  • JiriK:

    Hi, I found an Scorbot-ER V plus robot and controller from a recycling bin of local polytechnic school. Robot had it´s home sensor drums and one belt tensioner removed but I found them too and now it works… Except axis 2 and 3 seem to give collision warning if moved faster than ca. 35%. Bad motors? Also, is the pc software available somewhere? Controller came with teach pendant.

    • First of all – your local polytechnic school gives a new meaning to the phrase “dumpster diving” 🙂 – I am in awe at what can be found in a recycling bin there! Great job on saving a robot from destruction!

      I have to say I never encountered an issue with the collision warning at a particular speed – it looks like there may be extra friction somewhere – belts overtightened? Something in the gearboxes? The gearboxes can be taken apart if necessary – I have done it before due to stripped gears. Just keep track of what gear goes where when you put them back together. If yours goes through the whole range of motion at the slower speed, then you don’t have stripped gears, which is great! Try to oil everything that moves, too – who knows, perhaps some axles are seizing up?

      As far as software, I only have a copy of Scorbase 3.5 here but I am not sure if it will work with your controller. I do have a Scrobot V plus robot arm myself, but the controller I got is not working, so I can’t check.

      There used to be a Yahoo Group for Scorbots, which was a tremendous resource, but sadly, Yahoo pulled it, and I don’t know of any replacement.

      • JiriK:

        The school (Turku AMK Sepänkatu campus / Finland) is moving to a new site so they are clearing the building. I have found a lot of cool stuff from those bins. Luckily I took the controller when I saw it over two weeks ago. Found the robot last friday.

        I soldered an rs232 cable (D9-D25) and it seems to connect to robot controller using windows XP Hyperterminal, but not with that Scorbase 3.5. Maybe it needs different cable?

        Axis 2 servo output shaft seems to have quite a bit of play in it. I´ll take it out and see if the bearing is gone. Axis 1 has a lot of play, too. Old and well used robot.

  • Ernest Smith:

    The best thing to do with a functioning motor with a bad controller(expense wise) is to use ROS and make your own controller attach a joystick for operation with scorbot. use python for coding movements and teaching. There are sites have already tested this method on utube channels working with this configuration, this way you can save money on problems in the future by just replacing the motors and belts for operations.

  • Wayne Allsopp:

    Hi i find this site very interesting I have a Scorebot ER4PC and i cant figger whats the problem i try to home it gives me Scorbase error 201 position error the motion is to great or an impact has occurred axis 4 but neither have occurred that i can see

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