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dojoe / K2500-PRAM

A P/RAM extension remake for Kurzweil K2500 synthesizers
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Recommended J1 pin header has pins too thick for some K2500RS models #1

Closed psobot closed 2 years ago

psobot commented 2 years ago

Hi @dojoe! This project is great, and I had the pleasure of ordering boards and soldering one of these together recently. Unfortunately, after assembly, I found that the resulting PRAM board didn't fit in my K2500RS - and the pins used on the recommended part for J1 (Precision pin header, 45pos, 0.1" | e.g. 1212-1176-ND) were too thick for the connector on my K2500RS' engine board. (Even a single pin from the header wouldn't fit in the connector slot, when tried independently of the PRAM card; no amount of pushing on caused the pins to fit.)

It might be worth changing the BOM to recommend a header with slightly thinner pins, if one exists.

dojoe commented 2 years ago

Hi Peter! That's weird, I've built about six of these with the Preci-Dip parts and they all worked fine.

According to the datasheet the two sides have different pin diameters - 0.76mm at the mating side and 0.6mm at the solder side. I always soldered the thicker side to the board and had the slimmer side sticking out - wasn't even aware I was soldering them the "wrong" way around. Maybe that's what makes the difference between fitting and not fitting. Apart from this pin shape the only other shape I can find on Digikey is 0.47mm pin thickness; that sounds like it would simply fall out of the socket.

If flipping the header doesn't work for you, maybe one of the 0.47mm parts would work - ED3864-64-ND is one I just found that's got a 0.6mm and a 0.47mm side. Please let me know what you find out so I can update the README, and/or send a PR my way :)

psobot commented 2 years ago

Ah brilliant! Thank you @dojoe - I soldered the short side to the daughterboard and used the long side as the header pins. I'll order a couple more parts and try again. Thanks for the quick and detailed response!

psobot commented 2 years ago

Following up on this - I can confirm that flipping the header works perfectly. Just opened #2 to add a section to the readme.

dojoe commented 2 years ago

Thanks a lot for the follow-up and the PR! ❤️