Bun's Lab – Telegram
Bun's Lab
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Electronics projects, vintæg computing, programming and repairs. A minimalist blog of sorts.
@BunsGarden @BunsNook
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I picked it up many eons ago for 20 bucks on ebay. Now somehow it goes for 90-100?? With some people even asking outrageous 200 for it. The specs certainly haven't gotten any better. What is it with this inflation of retro gear prices lately?
Specs are printed on the bottom. Handy!
Luckily, as a vintage tech nerd I have plenty of replacement switches on hand. Probably could've even found the same exact type, if I had went on a little digging tour through my basement. But eh, I won't bother
The operation manual dates to October '79. It's already driven by a microcontroller, a MOSTEK MK3870 with 64 bytes of scratch RAM, 64 bytes of executable RAM and up to 4k of mask ROM.
The keen eyed among you will have already spotted another problem. Two segments on the LCD are out, along with two status indicators.
The LCD is a piece of glass with contacts deposited on it in a very thin layer. A rubbery piece with conductive inlays provides contact with the PCB. Held together by a plastic contraption. I gonna need a conductive pen to fix his.
The LCD is driven by CD4056 and CD4054 LCD drivers
Back together it goes for now. I'll postpone the calibration until I put one of the voltage references in a nice enclosure and got its accuracy verified. For the LCD I'll get a conductive pen and try that. Shouldn't be too hard to adapt LED 7 segments either. There is no way I could find a replacement for this LCD. It's definitively custom due to the indicators.
If I can fix the LCD display, it might be worth just throwing it on ebay and putting those 100 bucks towards a 5 1/2 or 6 1/2 digit meter. I really should upgrade
For completeness sake, here is the documentation of the Fluke