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2015's calculator anniversary - the SR-52
02-02-2016, 06:41 PM
Post: #19
RE: 2015's calculator anniversary - the SR-52
Today I have replaced the the ARITH/ALU chip from a donor SR-51A.

The problem remains the same, so my next suspect are the RAM chips.
In fact the RAM chips are usually the first ones to fail when over-voltage is applied as a result of using external adapter with bad or absent batteries.
I found this issue on a TI-58C some time ago, but was lucky to find RAM memory spares on TAS and could fix it.

But for this SR-52 finding spare RAM chip seems to be hopeless.

The good news is that the suspect ARITH/ALU TMC0501NL from the SR-52 is working fine when installed on the SR-51A Smile

Also, I have to say that these Texas PCB's from the 70's are much better than I already knew. This PCB have resisted to two chip extractions and insertions without a single pad being destroyed.

Meanwhile, our good friend Etienne Victoria came to rescue. Thank you!
Etienne has offered me a SR-52 working chassis that is coming my way.

I have been reading some of Etienne's past work posted here in the MoHPC in the old forums and have been enjoying it.

With two machines I hope to build one working calculator. The card reader will be another story, though.

Jose Mesquita
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RE: 2015's calculator anniversary - the SR-52 - jebem - 02-02-2016 06:41 PM



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