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Full Version: Another Red Dot Auction - Very Bad Condition
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Well, another HP-35 Red Dot is up for auction, and this one is in very poor condition. It is not working and has obviously been opened, so who knows what is going on inside. The only included accessory is the AC adapter, which is not original. It does appear to be authentic, however, so it will be interesting to see what the final price turns out to be.

(see here)

Personally, I wouldn't pay one cent for it. Maybe I'm weird, but I want a calculator that works.

I am with you Don. A non-working calculator is no fun!!!


I see Coburlin is in the running for it (his signature .88 bids). Let's hope he doesn't win and relist it for $12,000.

Nah. He's already overbid, and never re-bids. I know because he's bid on my auctions, which always start at a low initial price and are no-reserve. He'll put in a baby bid and then go away when the serious bidding starts. Don't you think $12,000 is kinda low? ;>)

...I want a calculator that works.

It might be trivially easy to fix. For example, classic chargers are notorious for developing open-circuits in the cord and plug, so perhaps the charger is all that does not work. Or it might be completely filled with corrosion from battery leakage. But if you want a red-dot, it might be worth the risk.


I might be inclined to agree with you, except that I'm suspicious that the problem may be more serious because the calculator has clearly been opened. If battery acid leaked through the contact openings and onto the circuit board, serious damage could occur. And then there's the real possibility that the logic board is missing.

Edited: 20 Mar 2009, 9:07 a.m.

Agreed. If I were going to bid on this unit, I would like to see a picture of the battery compartment or at least get a statement regarding its condition. I guess one could ask the seller - "is the logic board present?" Answer would likely be "I don't know, selling as-is." Caveat emptor.


FWIW - I have sent a message to the seller requesting precisely that, not that I have any intent on bidding since I already own a very excellent and complete red dot. Just curious to see what the answer will be. No answer yet.

usually, the 35s have been opened to clean the on/off-contacts
Btw. if this one doesn't have a PCB installed, you are mostly out of luck - the PCB connector is different from later versions (I think the early V2 still uses the red dot type, but you certainly don't want to rip that one apart...). It should be possible to replace the inner assembly though, if you want a red-dot-looking machine.

I think the ON/OFF switch design is different on the early HP-35 versions like the red dot, than on later versions and other classics (HP-45, HP-80 etc.). I have opened many classics to clean and re-grease the ON/OFF contacts with silicone dielectric compound, but my red dot switch appears different and works perfectly. Needless to say, it has never been opened and I have no intention of doing so.

I think the ON/OFF switch design is different on the early HP-35 versions like the red dot, than on later versions and other classics (HP-45, HP-80 etc.)...

Incorrect, red dots are identical to later 35's. The only obvious differences are that the red dot slides have a dot of florescent red paint on them and the calculator top has the small hole though which the paint shows when in the on position.

That is why there have been counterfeits - it's easy to duplicate to the untrained eye. There are several tells that reveal a fake but I really don't want to publish them... for fear of helping the unsavory.

I disagree as to the switches being identical. The ON/OFF slider switch on my red dot protrudes much less above the surface of the keyboard than my later HP 35 v3 or all my other classics with the single large slider switch. The red dot switch protrudes less than 2mm, whereas the HP 35 v3 switch protrudes 3mm. Also, the two switches have a very different and distinct feel to them. The later version switches all have a very noticeable detent at the full OFF and ON positions, whereas the red dot has none.

Nonetheless, you are correct about fakes, as there are other signs of this, which I too will not reveal here.

You are correct, the height of the slide is quite different. It was one of the things I originally had mentioned but then removed... when I realized I was writing a how-to guide on building a fake...

BTW, having looked at the mechanics of the slides and cases, the click and feel differences appear to best explained by the lack of or presence of lubrication on the two slide detents.

Edited: 20 Mar 2009, 8:08 p.m.