Today's Message Index:
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1. 09:48 AM - Re: OVM14 MkIII, rev P6 (Robert L. Nuckolls, III)
2. 12:09 PM - Re: OVM14 MkIII, rev P6 (Eric Page)
Message 1
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| Subject: | Re: OVM14 MkIII, rev P6 |
An update on the project . . .
I was scheduled to be receiving boards last Friday along with
parts-not-in-inventory.
While crafting the parts order, I had discovered a mis-match
between the semiconductor package used on the layout and
that of the SCR we were going to evaluate. Further,
I've not crafted an ECB using an SCR in too many years.
I was kinda 'locked' into dozens of recent layouts for
power handling MOS-FETS. Oops! The signal input pin
(gate) for the two devices are reversed. Be cautious
as you age . . . hitorical 'grooves' may feature
more pot-holes than you're aware of!.
Managed to stop the board order before they fabricated
and shipped $90 worth of trash. I've modified the
layout to fix the error -AND- to configure pads that
will accommodate a constellation of devices and
packages.
Further, while working the parts order, I discovered
an SCR with more attractive ratings. Don't know
why this device didn't surface during earlier
queries to Digikey's exceedingly capable search
engine.
I've upgraded to the more attractive SCR. Oh yeah, had
to use vias (top to bottom conductor transitions)
under the SCR heat sink pad . . . I've got some kevlar
tape that makes a nice insulator under power components
that suffer this shortcoming. Hat tip: Eric
Picked my environmental test chamber. Needs
a bit of refurbishment but it shouldn't smoke
when I plug it in! Looking forward to paying
homage to Jack Thurman's circa 1980 qualification
tests for OV management systems.
So . . . we're only set back one week. Be that as
it may, the board has been fixed. Any efforts to
validate my work product are most welcome.
Latest drawing package:
http://aeroelectric.com/AEC_Legacy_Products/9003/AEC9003%20MkIII%20Check%20Drasings%20P6.pdf
Bob . . .
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< Go ahead, make my day . . . >
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In the interest of creative evolution
of the-best-we-know-how-to-do based
on physics and good practice.
Message 2
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| Subject: | Re: OVM14 MkIII, rev P6 |
Lucky catch on the backwards footprint. It all looks dandy to me now.
I'd be very interested to read what you have planned for temperature testing.
I had a PCB screw-up recently too. I failed to notice the fine print on the board
fab's website stating that they don't support blind vias. I ended up with
a four-layer board that had via-sized pads top and bottom that weren't connected
to the internal planes. Fortunately, it was a very small board and therefore
a cheap mistake. Unfortunately, I didn't catch it until after I soldered
all of the parts to it and found that it didn't work. Oops!
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=511857#511857
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