kablooey

John Larkin · 2006-03-09T04:10:00+00:00

One of my better customers just called. Seems six of my VME arbitrarywaveform generators failed, in the same VME crate, simultaneously.We're talking over $30K of damage here.I had them put a scope on the +5 supply and switch power on. It rampedup in maybe 100 ms, peaked at 5.6 for a few ms, then settled down to5.1. That's above the 5.5 abs max for my CPU and FPGA chips, but notreally that bad. So I asked them to switch power off for various times, then back on. A2 second delay gave 7.5 volts peak. An estimated 0.5 sec delay, asfast as they could work the switch, ramped up to 8.8. I'm guessing anoptimum brownout might well hit 10 volts.Dumb switching power supply design... stupid loop dynamics and nocrowbar! I mean, one could easily load a VME crate with $100K worth ofboards. They're ragging the crate vendor next. Don't know who is goingto pay to fix the modules.I could add a transzorb to my boards, I guess, but the overshoot mightjust blow a hole in the board. Transzorb+fuse would work, but thatwould be an ugly kluge. 8.8 volts is sort of past my responsibility,I'm thinking.John

Mar 09, 2006 61 Replies

Rate this thread:

John Larkin 20 years ago

I did change a few clutches on my Honda motorcycles. It took about 10 minutes and you didn't even get your fingernails dirty. Of course, most of them were stolen before they needed new clutches.

John

Vote

mrdarrett 20 years ago

Clutchless, in San Francisco? (shudder)

I remember when I was learning stick-shift for the first time (oh, around '94 or '95), and my friends and I had this wonderful idea to go visit San Francisco. Stalled big-time on those hills... with a truck behind me...

Vote

Join the Discussion

Have something to add? Share your thoughts — no account required.

Didn't find your answer?

Ask the community — no account required