hp97 red light
#1

I've seen several hp97's on ebay in non-working order, the sellers say it powers up but only a red light turns on, not the numbers on the display. One also mentions a humming noise.
Does anyone know what error/damage this means, and is it easily fixed?

#2

Hello!

This is normally a sign of too low voltage. Most probably, the recharchable battery pack is dead (internally short circuited). The humming sound comes from the overloading charger.

Disconnect the charger immediately and replace the battery cell! If the seller or previous owner has "experimented" with the calculator in this condition, there is a good chance, that the charger or some circuits inside the calcultor have suffered permanent damage.

Greetings, Max

Important: Do NOT connect the HP-97 to the charger without a (good!) battery pack in place.

#3

O.K., so better not bid on one of those then.
Thanks!

#4

Hi!

> O.K., so better not bid on one of those then. Thanks!

Well, as long as you don't bid too much, you can always give it a try. If you are lucky, you get a wonderful machine (the HP-97 is one of my top-5 favourite calculators...) for the additional price of 4 replacement NiCd cells and 30 minutes soldiring work.

Greetings, Max

#5

The humming sound is probably the printer motor running in a machine with a bad gear. This can also lead to the blank display... the machine is waiting for the printer head to return home.



Possibly Related Threads…
Thread Author Replies Views Last Post
  Another HP 35 Red Dot on eBay Michael de Estrada 5 2,375 11-09-2013, 03:07 PM
Last Post: aj04062
  Light spectrum on HP Prime Mic 2 1,211 09-19-2013, 12:47 AM
Last Post: Mic
  Calculators usable in dim light Marcel Samek 10 2,746 03-09-2013, 01:08 PM
Last Post: Eddie W. Shore
  Disaster: help for a couple of HP97 needed! Jose Gonzalez Divasson 10 2,925 01-21-2013, 04:45 PM
Last Post: aurelio
  HP 35 Red Dot page Michael Eckstein 6 2,306 11-05-2012, 03:03 AM
Last Post: Michael Eckstein
  Charging Current in HP97, 82143A, 82162A Les Wright 5 2,036 06-17-2012, 02:11 PM
Last Post: Les Wright
  can you identify this HP97-67 book? Ignacio Sánchez 4 1,894 06-13-2012, 01:02 PM
Last Post: db (martinez, ca.)
  [WP-34S] Zero G Milestone. Red Barron Deployment. Chris Tvergard 11 3,201 05-28-2012, 12:23 PM
Last Post: Walter B
  RED HP71 John W Kercheval 26 6,488 05-24-2012, 07:39 AM
Last Post: Keith Midson
  Another Red Dot Auction Michael de Estrada 7 2,507 04-07-2012, 09:47 AM
Last Post: Michael de Estrada

Forum Jump: