I've got a few machines that need a new DS1742W-120 (Fuel, O350). I'm kicking off a thread because we somehow don't yet have a Dallas thread
I ordered some replacement DS1742W-120's from ebay -- the seller had -120's listed, a -120 was pictured, but -120+ was what I got. This, in theory, should be fine; the "+" just signifies RoHS and should have no functional difference. Unfortunately, from the time of SGI's DS1742W's to.. whenever these were manufactured, it looks like the physical specs of the chip changed.
The original -120 chip that was in my Fuel has pins that are .20mm x .40mm (one of the biggest I checked, they vary by ~.02mm). The new -120+ pins are .30mm x .58mm, so almost 50% larger in each dimension. The DS1742 data sheet lists pin size to be 0.25-0.45mm x 0.43-0.58mm, so the new chip is right in the middle of that spec. The old one is way under.
SGI used a socket with really small round pin holes; the new chip pin size physically does not fit. A standard 2.54mm-spaced header (typically .63mm square pin) does not fit into them. However, a 1.27mm header with every other pin removed fits nicely (these are typically .40mm square pin). (The new chips are also physically bigger; there's a capacitor on the fuel that the new one barely clears.)
I've got a variety of adapters, but I'm not hopeful as I think they'll all have way too thick pins. I suspect I'll have to build my own; the smaller pin size but with a 2.54mm pitch does not seem to be a thing in any existing adapters.
I ordered some replacement DS1742W-120's from ebay -- the seller had -120's listed, a -120 was pictured, but -120+ was what I got. This, in theory, should be fine; the "+" just signifies RoHS and should have no functional difference. Unfortunately, from the time of SGI's DS1742W's to.. whenever these were manufactured, it looks like the physical specs of the chip changed.
The original -120 chip that was in my Fuel has pins that are .20mm x .40mm (one of the biggest I checked, they vary by ~.02mm). The new -120+ pins are .30mm x .58mm, so almost 50% larger in each dimension. The DS1742 data sheet lists pin size to be 0.25-0.45mm x 0.43-0.58mm, so the new chip is right in the middle of that spec. The old one is way under.
SGI used a socket with really small round pin holes; the new chip pin size physically does not fit. A standard 2.54mm-spaced header (typically .63mm square pin) does not fit into them. However, a 1.27mm header with every other pin removed fits nicely (these are typically .40mm square pin). (The new chips are also physically bigger; there's a capacitor on the fuel that the new one barely clears.)
I've got a variety of adapters, but I'm not hopeful as I think they'll all have way too thick pins. I suspect I'll have to build my own; the smaller pin size but with a 2.54mm pitch does not seem to be a thing in any existing adapters.