Saturday, June 11, 2016

Sylvester chomps at the bit...

Our Grumman Kurbwatt rebuild at Sumner High school is nearly complete, and just in time for the end of school.  There's an annoying no-start error light flashing on the Zilla controller's hairball (brain), caused by critical low voltage on the 12V circuit, according to the error code extracted.  However, after wiping the error code and doing a couple of disconnections of both 12V and the traction pack, the hairball just lights up red with an error again upon attempted restart.  No fuses blew, big or small, but research reveals that early hairball firmware could be corrupted by this very condition. I spent this week rounding up equipment to talk to the 9600 baud serial port on the hairball, which has become a challenge in the modern era.  (I've dredged up a serial terminal that just spit out code that I couldn't comprehend, and now a Palm Pilot with a serial cord, as well as a USB-serial adaptor for my laptop, and a couple of programs to try.  To further complicate matters, the hairball is no longer flashing codes or resetting using the simple 'shorting plug' signals of last resort.  Oh well, if all else fails it's good to be close to Manzanita Micro here in WA for repair.

The main activity of the past couple of weeks was to go ahead and install the second battery pack: ten more modules in parallel with the ten installed in the slide-out battery tray.  These are tucked away in body cavities below and behind the seats, and though permanently paralleled, one can run one or both packs with selective use of the Anderson SB350 connectors.  Replacing the terminal posts with contactors would enable series/parallel switching of the packs, for 240V 'strip' or 120V 'street' operation, but from the initial road tests, it may be that 120V will be plenteous power, given a doubled-up pack rated for 1000 amp discharges!

We also replaced the rusty sideview mirrors and both of the driveline half-shafts complete with four CV joints, but that turned out to not be the source of an annoying clicking sound when making left turns.  More diagnosis to come once it's running again next week.  Lastly, I finally found replacement gaskets for the round stop/turn/reverse lights and sealed in some really bright LEDs that should be a snazzy safety enhancement.

Speaking of safety, one student demonstrated the value of safety glasses after carefully removing a window, cleaning and lubricating the chain-drive regulator, and reinstalling it, only to have the window shatter when he turned the crank.  No good turn goes unrewarded, but that window was luckily a match to all of the big brother Grummans, and replaceable for only $30 from Mill Supply!

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