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Finally another Woodstock low power candidate :-) Non-working Woodstocks in such beautiful shape are very hard to find!

I'll take this obvious burial case off your hands.
My WS LP needs a host....


Pauli

(04-22-2018 09:04 AM)emersone12 Wrote: [ -> ]Couldn't have been many HP-25's made in the USA before transferring production to Singapore. Seems to have been a routine for HP to start initially manufacturing in the USA before transferring manufacture to Asia.

My first HP-25, purchased new in 1977, was made in Brazil.

(My current one, purchased about 10 years ago on eBay, was made in the U.S., May 1976.)

The case backs on Woodstocks can be replaced without breaking any seals or removing any labels, so unless you are the original owner, there is no guarantee that a Woodstock with a label that says Made in USA and a nnnnAnnnnn serial number was actually made in the USA. All of my Woodstocks were Made in USA.

If someone has powered this up using the mains psu, without a battery pack in the back, it's possible the internal chips may be toast, no? I thought the batteries had to be present to prevent the psu over-voltaging the circuitry. Certainly is the case with my 29C, which I've been very careful never to do this to.

Quote:If someone has powered this up using the mains psu, without a battery pack in the back, it's possible the internal chips may be toast, no? I thought the batteries had to be present to prevent the psu over-voltaging the circuitry. Certainly is the case with my 29C, which I've been very careful never to do this to.

Yes, you are right. It is toast and several days ago I sent the seller a note informing them of that and enclosing a screenshot from the HP25 manual (p.102) telling not to plug it in without a power supply. I suggested they might want to put that on their ad in the interests of being open in the listing.

They replied rather laconically "thanks for the info" and left the listing unchanged. To be fair, they do indicate what now happens when they turn it on while plugged in and say they are selling it for parts only. It does look like it would make a nice Woodstock LP.

burkhard

(04-24-2018 04:12 PM)AndyWalter Wrote: [ -> ]If someone has powered this up using the mains psu, without a battery pack in the back, it's possible the internal chips may be toast, no? I thought the batteries had to be present to prevent the psu over-voltaging the circuitry. Certainly is the case with my 29C, which I've been very careful never to do this to.

Even if a battery is installed, the calculator circuitry can be ruined if the battery is bad with high internal resistance or makes poor contact with the calculator terminals. My rule is to NEVER connect the AC adapter to the calculator, and recharge the batteries externally.

Quote:Even if a battery is installed, the calculator circuitry can be ruined if the battery is bad with high internal resistance or makes poor contact with the calculator terminals. My rule is to NEVER connect the AC adapter to the calculator, and recharge the batteries externally.

Amen. You are very correct.

Really this is the safest course: Tie a tag on the charger that says "For historical purposes only. DO NOT use. Only charge batteries for HP model calculator 21, 22, 25, 25C, 27, 29C outside the calculator. Using this charger can damage the calculator", and then box it away for your heirs to find someday when they are sorting though your hoard.

I think a lot of the wasted ones come up on eBay when somebody cleans out departed grandpa's stuff and start plugging what they think is an adapter in to "See if this old junk still works".

It was a really terrible design feature even back in the day when everything didn't have to be "idiot-proofed".

burkhard