Sinclair Expansion pack RAM

Posted by EsoTechTrix@reddit | vintagecomputing | View on Reddit | 10 comments

I've got to say. I'm both impressed at the board they put together for the Sinclair RAM expansion module and annoyed at the notion of having to try and swap some of these chips.

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bwyer@reddit

With a proper desoldering tool (like an actual gun) that would be trivial. Hakko has some great options.

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EsoTechTrix@reddit (OP)

I have the equipment. Just less of the excitement to deal with it. 🤣

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bwyer@reddit

Now that I get... I have four upright video arcade games that are currently broken (fried due to a power issue) that have been dead for quite a long time. I just can't get the motivation to fix them.

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EsoTechTrix@reddit (OP)

I finally have a 4x4 CNC and I should be cutting out an upright shell.

So many projects, so little time.

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SpookyTheCat96@reddit

Amazing how neat and perfect these solders are. Would these have been done by machine then, or hand soldered?

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EsoTechTrix@reddit (OP)

I believe they are wave soldered. I'm sure someone will correct me if I am wrong.

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tall_cappucino1@reddit

Impressive soldering!

By the way, what does the 4NS mean? That can’t be nanoseconds, can it?

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EsoTechTrix@reddit (OP)

They are 250ns, so I guess "quarter microsecond"?

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I have a RAM expansion for an old notebook computer of the same era, and there they stacked the chips on top of each other and soldered all but one pin on each to the ones below. I think the stack was 4 chips high.

The last pin was of course the Chip Select pin.

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scubascratch@reddit

Hah hah that’s a tight layout for DIPs for sure.

If the ram chips are bad for sure then you can be a bit more destructive and clip the leads individually with some small cutters to get the chip body out then it’s much easier to unsolder one cut pin at a time