General Category > Lisa Troubleshooting and Repair

Two sick Widgets

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stepleton:
I only ran across that "Deep Dive into Widget" article a few weeks ago! I still have it open in a browser tab. Among other things, the article provides clear information about the SysRead and SysWrite commands that tempts me to finally add them to NeoWidEx. Right now these are marked as "not implemented yet" as I hadn't taken the time to try and understand the protocol in detail. The lack of these commands is one of the things blocking NeoWidEx from a 1.0 release :)

Thanks for taking the time to write the article!

stepleton:
No real progress to report from simple interventions with the two sick Widgets, but at least we might be able to eliminate certain possibilities.

I first tried @compu_85's head-turning advice on Widget 1, but regrettably (for hopes of having a quick answer) it seems to move freely: it is easy to rotate by the axle and moves cleanly from stop to stop.

I then tried swapping the servo, read-write, and controller boards between both Widgets, but there is little to no change. Widget 1 still attempts to move Head 1 on startup but doesn't ever sound like it successfully completes a recal. Widget 2 can still only read from Head 0 --- diagnostic reads from Head 1 produce random data that changes between reads.

I tried doing some probing on the Widget 2 motherboard with an oscilloscope, but didn't get very far. I think I need to take time to understand it better; also, signals from the arm are very slight. There is also the idea of interchanging the motherboard between both drives, but this will probably require an optics recalibration each time.

In any case, given that board swapping doesn't change behaviour very much, it seems like the problems with both Widgets are now narrowed down to the mechanism itself or to the motherboard. (I assume that the motor board is fine for both.) I'm not 100% certain of this, though.

compu_85:
I've read the calibration procedure for the motherboard's pots a few times.... and still don't understand it :/

I've gotten 1 or 2 dead Widgets going again just twiddling those adjustments and listening to the sound of the stepper  :o

I have one drive with a very low SN mechanism which works OK, but just can't "fast seek" as well as the drive in my 2/10. The startup scan takes a bit longer, with more time between steps.  I suspect a proper tuneup would make this better.

-J

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