HP-34C Won’t Power Up

[Steve Simpkin]

(02-24-2021 10:47 PM)stevenme Wrote:  

(02-23-2021 01:11 AM)mfleming Wrote:  He's dead Jim.

Was it that I connected the AC charger without the battery installed that killed it? Just wondering for future reference. Thanks!

Yes. Unfortunately HP engineers used the batteries as a voltage regulator in the HP-2x (aka Woodstock family) and HP-3x (aka Spice family) models. Trying to operate these models from the AC charger without the batteries installed usually instantly destroys the ACT chip at a minimum. This can also occur if the batteries are making a bad connection (for example, due to corrosion) or if one of the batteries failed in an open state. The manuals for the HP-2x had somewhat dire warnings against doing this at the beginning of the manual and in the battery charging section. The HP-34C manual only hints at not to use the AC charger without batteries installed on page 270. Not good considering the almost certain damage that would occur.