Ice Tube digit 6 intermittent
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Ice Tube digit 6 intermittent

by Grant on Tue Nov 27, 2012 7:21 pm

I've just finished building an Ice Tube clock kit, and digit 6 doesn't
light up most of the time. If you tap very lightly on the glass tube
with a fingernail, it will sometimes come on for a while.

I brought the boards in to the hardware lab at work, and used one of
the inspection microscopes to check the solder joints on

* the PLCC socket
* both 20-pin headers
* the VFD tube leads

I paid special attention to the connections that I _think_ are for the
VFD6 net, but since there are no pin 1 indicators on the silkscreen
for the headers and VFD tube, it's sort of hard to tell.

They all looked fine, but I re-flowed any of the ones that were even
remotely questionable and then cleaned the flux off the boards. [I've
been soldering a long time, and do a pretty good job until I get to
the really fine pitch surface mount stuff -- though I do have to use a
microscope for stuff that I didn't in my younger days.]

Didn't help.

Can somebody point me to pin 1 positions for the headers and the VFD
tube so I can put a scope on the digit select lines to check them?
The pinout for the PLCC socket would also be great. (Or are PLC28
socket footprints all the same? It's been a lot of years since any of
my projects used PLCC sockets.)

Do VFD tubes ever have flaky digits/segments right out of the box?

I do actually have a spare tube from a previous Ice Tube kit, but I
don't have a spare board/header to solder it to -- about half the
parts in the previous kit got lost. It's a long story involving a
tornado and a couple of toddlers.

[This sure is more fun than troublshooting 7-layer boards full of BGA
parts and blind vias.]

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Joined: Wed Sep 16, 2009 5:45 pm

Re: Ice Tube digit 6 intermittent

by adafruit_support_bill on Wed Nov 28, 2012 6:38 am

Pin 1 (VBias) on the main board header is the pin closest to SW-1. Follow the trace from the end of R3. The pin numbering on the tube-board header is a mirror image of that: Pin1<->Pin2 and Pin2<->Pin1. The board files are here: https://github.com/adafruit/Ice-Tube-Clock (Eagle is available as a free download - if you don't already have it) You can follow the bridged ground pins on the header (11 & 12) to pin 1 on the tube itself.


We do test each tube prior to shipment, but they are rather delicate and don't always arrive intact. An easy way to isolate a tube problem is to short the pin of the flaky digit to an adjacent digit. If the digit lights up (should echo the adjacent digit) then it is not the tube.

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Joined: Sat Feb 07, 2009 10:11 am

Re: Ice Tube digit 6 intermittent

by Grant on Wed Nov 28, 2012 10:57 am

Thanks for the quick reply. I do have Eagle, so the layout files will be useful.
Posts: 10
Joined: Wed Sep 16, 2009 5:45 pm

Please be positive and constructive with your questions and comments.