Hp 71b power fault


Hi all,

This is driving me NUTS. My 71b is fine on batteries but when powered from an AC adapter it keeps losing power and switching off. I thought that maybe it was a faulty wire from the AC to the recifier so I re-soldered these (The thin green and pink ones wound on the choke). It's STILL doing it. The behaviour can be aggrivated by wiggling the AC plug into the machine. What else could be loose ? Could it be that the actual pins are not being held tight enough by the adapter plug ?

I have no batteries inside themachine when I am doing this


PS I'm an electronics engineer so I don't mind swapping stuff out or soldering



Have you checked to see if connection on the pins are good inside the unit? Also if the AC cord has been wrapped tightly, the strands inside it could be broken. Otherwise as you said it could be a loose fitting plug.


Possibly Related Threads…
Thread Author Replies Views Last Post
  HP Prime Save Power Turn Off Not Working Timothy Roche 12 4,177 10-27-2013, 01:41 PM
Last Post: Michael de Estrada
  HP 32sii Fault Carlos Estinos 9 2,876 09-26-2013, 01:06 PM
Last Post: Csaba Tizedes (Hungary)
  Low power warning for HP-15C LE and batteries Nick_S 1 1,415 09-16-2013, 09:34 AM
Last Post: Hans Brueggemann
  HP 9845 option 200 power supply Dave F 2 1,603 05-30-2013, 08:10 AM
Last Post: Dave F
  HP-87 power supply repair philippe_elie 0 923 11-18-2012, 11:12 AM
Last Post: philippe_elie
  HP-48: extract coefficient of power series Thomas Klemm 3 1,539 10-21-2012, 11:42 PM
Last Post: Han
  HP-41CV power problem Don Davis 2 1,275 10-11-2012, 09:13 PM
Last Post: Don Davis
  What power adaptor does an HP-65 use? Robert Morton 3 1,424 09-30-2012, 02:32 PM
Last Post: Kees Bouw
  HP 15c LE low power anomalies Nick_S 21 5,125 03-31-2012, 09:32 AM
Last Post: uhmgawa
  Very relevant to the HP-15C LE power usage Seth Morabito 1 984 01-06-2012, 10:38 PM
Last Post: htom trites jr

Forum Jump: