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  1. #1
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    Default Question for VFD experts.

    I have two Sumitomo AF502-3A7 drives on a cylindrical grinder. Both are hooked up the same way. The drives mount on the back of the machine and are controlled by two boxes in the front. The drives can be programmed to work off their panels or remotely, which I am doing. One does exactly what the manual says, start is controlled by the forward run line and speed is by a pot with 12 volts DC across it.

    The change from panel to remote is changed by Code 4 set to 0 or 1. One drive shifts start and speed as the manual says. The other moves the start to remote but not speed. I can change speed on that one by the up/down arrows when it is set for panel control but not in remote. The speed control voltage is varying with the pot setting, so there is no failure there. The manual also says that code 35 changes panel key functions from panel to remote. It is locked on 1 on both drives, when I enter a 0 they change back. The information may be in the manual, but it is not indexed and I have to find things by reading through a lot of unrelated information to find it. I only found the code 4 function by a footnote in tiny print.

    Any suggestions?

    Bill

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  3. #2
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    Are these ones installed new?

    If not, or if some "expert" set them, here is a chance that there is programming that was set and locked out from change. Note al the desired changes, then find the "factory default" reset code, and use it.

    Then make the programming changes again. That should take any special programming off them, so that they will act as the manual says (I assume they really are the exact same model with no special codes on the model number etc.)

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    That's exactly what happened with the new in box Hitachi drive I bought. Some of the parameters were locked out, and it took a good bit of page shuffling to find out how to undo that. The parameter set was three levels deep, the one I needed was midway in the third level.

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    I read and recorded all the commands on both drives, then changed the bad one to the same command set, to the extend it was possible. Some won't change. I then changed to the default settings. No joy in either case. I'm convinced that there is a malfunction in the drive.

    The resulting problem is that the owner doesn't want two different drives on the same grinder, doesn't want to pay Renwell $800 for a replacement. That leaves me with trying to find a replacement cheap or a repairman. There are some on EBAY but most are either pricey or untested, making them a crapshoot.

    The Sumitomo tech aid guy is helpful but there is nothing available from them, no schematic, no parts.

    This is an example of the high cost of doing something cheap, but I have a customer to keep happy. Does anyone know a repairman who could work on it?

    Bill

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    In my experience, re;airs are unproductive in general, unless there is no chance of a new one.

    Because Part of the apparent failure is a code failure, i.e. the code chsnge that should do something does not, there is an added issue, which may not really be fixable.

    For any "does not respond to inputs on a particular line" type issue, the interface PWB can be tested reasonably well, it is substantially analog on any VFD.

    For "does not respond to a code input" problems, that involves programming internal to the device, which you have no access to.

    The only thing that could still be the case, and you need to search the manual for this, is that some units have a multi-level blocked function feature.

    You clear one with a certain code, but there is a second level with a different code in a different register. These are put in to prevent "Bubba" from bypassing things and fouling up programmed operation.

    If you cannot find anything in the book, ask the Sumitomo guy, emphasizing that you just want to wipe it.

  9. #6
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    The final solution to the VFD problem, after my wasting more time than a new one cost, was to turn it into a brand new one with factory support, etc. We found one shop that said they had worked on the old model- in 1997, none since, and they flat rated the repair at more than Radwell wants for a new one.

    Bill


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