Solarbird Mar 12, 2023

so if you’ve wondered what’s inside of one of those 16-interface USB3 breakout interfaces boxes - this one being a zmuipng which is popular somehow - here are photos.

to open it you remove the two long rubber feet then remove the two revealed screws, then spudger the top off starting on the short sides. lever them up alternately and it’ll come clear without too much of a fight. But be careful about the headphone jack! It's fragile. I damaged this one taking it out.

#electronics #diy #zmuipng

Show threadSolarbird Mar 12, 2023

Anyway, the reason I'm taking it apart is that is has an intermittent fault (best kind) that makes it start blanking all the displays hooked up to it, turning them on and off. This is generally after it's been running for a while so I suspect one of these chips is getting real hot.

And there is. It's this one. It's not anything that I think of as out of temperature yet, but it's a good 10°C hotter than everything else and it's only been running a few minutes.

Show threadGary GoughMar 12, 2023
@moira
Just sharing a past trouble shoot. I found a cracked trace under a memory chip in an Amiga 1000 once. Symptoms were, it booted fine, became intermittent after a few minutes and then returned to stable operation if left running after about 15 minutes. Different expansion rates for the chip, copper and fiberglass board by my guess. Found it by measuring end to end resistance of the traces.
Wasn't the first thing I thought of. 🤓
Show threadSolarbird 

@GaryGough good job!

this thing is way too fine-pitched for that tho' - if it's something similar, it's done.

Mar 12, 2023 at 10:06pmWeb
Show threadGary GoughMar 12, 2023
@moira
Yeah. It was easier when you had a row of largely parallel connected chips, and could just jumper between two to fix the problem. I'm hardly steady enough anymore too, but that's another issue. I've also caught cold solder joints with a heat lamp and freon spray ( you can guess how long ago from the material used ) compressed air might serve as well.
Show threadSolarbird Mar 12, 2023

@GaryGough YIKES freon

nice ozone layer y'got there

shame if somethin' were t'happen to it xD

Show threadGary GoughMar 12, 2023
@moira
Yep. We used to use that stuff as head cleaning fluid on video tape drives too.
Carbon tet, PCBs, lots of stuff I used to work with that is deservedly out of circulation.
Trivia, the door handles on model T fords weren't chrome plated, that was cadmium.
Show threadSolarbird Mar 13, 2023

@GaryGough CARBON TET

that's a name I haven't heard in a long time

a loooong time

( xD )