HP 41CV Repair
Posted: Wed May 06, 2009 7:54 am
Help !
I have an HP 41CV that has been my trusted servant for many years but has now died.
Problems started about 6 months ago when it started eating batteries, previously a set would last about a year but were now down to a few weeks.
There were a number of postings on the web which suggested that this problem was due to a break-down of the capacitor C1 which holds the memory during a battery change.
I opened the 41 up and changing C1 looked straightforward so I replaced it with a new 470uF capacitor, the only difference being that the new one was a 16 volt as opposed to the original that was 6.3 volt but I don't think that should matter.
After re-assembly I inserted the battery pack and immediately (without touching the on button) the display came up with a string of 'hieroglyphic' characters and would not respond to any keystrokes.
I have since cleaned all the contacts on the back of the CPU board and on the silicone rubber strip below. I have also tried putting some thin rubber washers over the mounting posts to increase the pressure on the contacts.
Finally in desparation I put the original C1 back but all to no avail !
The guy who replaced the capacitor for me spends most of his time repairing circuit boards so I am reasonably confident he won't have damaged anything on the board in the process, especially as the capacitor is right at the edge of the board.
I guess I must have disturbed something when I opened the case but I can't see any dry joints etc.
Can anybody help ?
Does anybody know of someone in the UK who can fix HP 41s ? - I am aware of FixThatCalc in USA but don't really want to ship it out there.
I have an HP 41CV that has been my trusted servant for many years but has now died.
Problems started about 6 months ago when it started eating batteries, previously a set would last about a year but were now down to a few weeks.
There were a number of postings on the web which suggested that this problem was due to a break-down of the capacitor C1 which holds the memory during a battery change.
I opened the 41 up and changing C1 looked straightforward so I replaced it with a new 470uF capacitor, the only difference being that the new one was a 16 volt as opposed to the original that was 6.3 volt but I don't think that should matter.
After re-assembly I inserted the battery pack and immediately (without touching the on button) the display came up with a string of 'hieroglyphic' characters and would not respond to any keystrokes.
I have since cleaned all the contacts on the back of the CPU board and on the silicone rubber strip below. I have also tried putting some thin rubber washers over the mounting posts to increase the pressure on the contacts.
Finally in desparation I put the original C1 back but all to no avail !
The guy who replaced the capacitor for me spends most of his time repairing circuit boards so I am reasonably confident he won't have damaged anything on the board in the process, especially as the capacitor is right at the edge of the board.
I guess I must have disturbed something when I opened the case but I can't see any dry joints etc.
Can anybody help ?
Does anybody know of someone in the UK who can fix HP 41s ? - I am aware of FixThatCalc in USA but don't really want to ship it out there.