With the lathe running and the display flashing 8888, if I disconnect the encoder, the display returns to 0. Once reconnected, the display shows the current RPM.
The controller is the KB-240D model from KB Electronics in the US. I was worried it might be a cheap clone when I ordered the box but was happy to find it wasn't. The IC is indeed socketed and has a readable number if it should turn out to be suspect. I'm still puzzled by the fact that the fault only crops up after some time. This is why I was tempted in the beginning to think it could be a thermal intermittent problem: something gets warm then fails. Off for a few seconds then it's ok again.
I don't have a scope and frankly, wouldn't know how to use one. As I indicated, my troubleshooting abilities are as good as my Swahili! That said, I do have a multimeter and a couple of spare opto-isolators I could try. Would they have to be exactly the same part number or are they mostly interchangeable?
I'm not at home right now so it'll be a while before I can get back to it. When I do, I'll post a few images.
Once again, I'm very grateful for your help.
Trevor
The controller is the KB-240D model from KB Electronics in the US. I was worried it might be a cheap clone when I ordered the box but was happy to find it wasn't. The IC is indeed socketed and has a readable number if it should turn out to be suspect. I'm still puzzled by the fact that the fault only crops up after some time. This is why I was tempted in the beginning to think it could be a thermal intermittent problem: something gets warm then fails. Off for a few seconds then it's ok again.
I don't have a scope and frankly, wouldn't know how to use one. As I indicated, my troubleshooting abilities are as good as my Swahili! That said, I do have a multimeter and a couple of spare opto-isolators I could try. Would they have to be exactly the same part number or are they mostly interchangeable?
I'm not at home right now so it'll be a while before I can get back to it. When I do, I'll post a few images.
Once again, I'm very grateful for your help.
Trevor
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