If I were to buy an LED model...

[Dave Britten]

(11-09-2019 03:10 PM)Trond Wrote:  Interesting that you mention it. I have also had a HP 41CV for a while (haven't used as much as I thought because some keys are bugging me), and I recently bought a HP 34C in good condition(see the other thread on that).

If some of the keys take a bit more force to register, then this is fairly easy to fix with a little Deoxit (red): use the precision tip to deposit a tiny amount of the fluid through the back of the PCB via the hole located under the keys in question. But the tricky part of it all is being very careful not to crack the screw posts, while also keeping the various pressure-fit connectors tight and clean enough. It probably took me at least 6 disassembly/reassembly cycles to get mine running reliably again after fixing a couple of the keys.

(11-09-2019 03:10 PM)Trond Wrote:  The HP 34c is very good, and I'm frankly loving it. Unlike most LED calculators it has continuous memory, and root finder. I also really like the robust feel of the keys on this one. I really like the display too.

BUT many people have complained that the first batch of 34C was fragile, and often breaks down, while later batches were more robust (mine must be one of the latter). Also, before buying, take a good look at the battery lid and compartment, as this area can also often have problems.

Perhaps all the marginal ones already broke down and were discarded before 1990, and all we're left with now are the more reliable specimens.

(11-09-2019 03:10 PM)Trond Wrote:  HP 67 is said to be the most robust LED calc with one major exception : the wheel for the card reader which nearly always needs to be replaced. I was considering finding a 67 with a repaired wheel, but they are horrendously expensive.

Yeah, that's kind of the "Achilles' wheel" of the 67, and just about any model with a card reader. Doesn't the repair just involve cleaning old gunk off the roller with an appropriate solvent, and popping on some new O-rings? Or is there more to it?

Honestly though, as heretical as it may sound, I'd probably opt for a TI-59 if I were buying a card-reader LED model. It's cheaper, more readily available, has more memory and more functions, has both a card reader and software ROM modules that can complement one another, plus it works with that great big printer dock. But if a 67 (or 97) fell into my lap, I certainly wouldn't say no!