Electronics > Beginners
Trying to find old 8k sram chips for HP-75c calculator pod
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james_s:
What was considered ultra low leakage current when the HP-75 was made is nothing special today.

https://www.digikey.com/product-detail/en/alliance-memory-inc/AS6C6264-55SCN/1450-1037-ND/4234596

1uA typical standby current, 2.7-5.5V supply range, 55ns access time, 28 pin SOP, current production part and only $2.13 each in single quantity. Am I missing something? Because this looks like a fully compatible and superior part.
oPossum:
That looks like a nice universal replacement for 6264 RAMs. Fast, low power, and DIP/SOP/TSOP packages.
chickenHeadKnob:
As Kjelt tried to caution RichardM I would also doubt that the RAMs are faulty. I would not eagerly replace them first as they do not just go bad on their own. Only two things commonly kill them, static discharge and an out of range power supply. In either of those two cases it is more likely for a static discharge to go through what ever is connected to the keyboard, likewise a power rail disruption or reversal could easily kill everything not just the RAM.

You can measure the resistance of the cruft on the PCB with a multimeter if it is conductive enough.
james_s:
I thought he wanted additional chips to fill blank spots on the board, not to replace suspected faulty parts?

I've seen a lot of faulty SRAM chips on old arcade games but those are mostly 2114's.
chickenHeadKnob:

--- Quote from: james_s on July 05, 2019, 12:59:53 am ---I thought he wanted additional chips to fill blank spots on the board, not to replace suspected faulty parts?

I've seen a lot of faulty SRAM chips on old arcade games but those are mostly 2114's.

--- End quote ---

Oh I see now, both wraper and kjeltthought led me to think this was a repair. Kjelt mentioned Richard would have to "unsolder" the chips himself. But richard says he wants to upgrade and that the device is working, my bad for skimming the replies. so ignore previous message. I have never had a bad SRAM even once on any repair.
I am just chock full of failtard sauce today  :palm:
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