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HP41c Repair Spree !


During the last week I have tried to repair (or install CL circuits on calculators) many calculators: 17 of them, of all types and flavours!

Again, repair statistics are quite stable, but there is a jump between 1st and 2nd:

  • Most frequent damage is broken upper screw domes in the back of the calculator. This happened in 13 out of 17 units!!
  • The second more frequent is corroded battery bay connectors. This happened to 11 of the 17 units. The corrosion also spread to the main board in several of the cases, but in all units I was able to remove it with our trusty Caig Deoxit.
  • The third most typical problem is broken lower screw posts. It happens to 7 out of 17 units. I have used exclusively our new piece, which penetrates below the keyboard circuit surface and grips on the sides. The design so so that when the screw enters, it presses harder to the sides, the same way a wall expansion screw works (plastic+screw). I think it doesnt make sense to continue with the old part - but let's see the durability of this new one for a while before making the change and discontinuing the old part.
  • Fourth in line is screen problems. So far 5 out of 17 have this problem, in several flavours:
    • ​a couple of units with a LCD with black areas
    • Not all segments lit, or not well enough.
    • Damaged screen driver. This can be seen when the screen lits only when a key is pressed. 
    • broken screen
  • ​Some other repairs involved changing the zebra connector - but most of the units used the double-zebra original piece, which is much better than the other two original zebra types and can be reused unless corroded.

​​All in all, a good week where we have managed to repair 13 of the units, there are still 3 to go and one completely unserviceable! Some have already been sent to their lucky owners.

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Jonathan Hacker |
RE: HP41c Repair Spree !
My 41cx has been a champ for 40+ years but suddenly the 4 upper toggle keys (on|user prgm|alpha) have become super stiff. I don't know how they are sprung but something has changed in literally 1 week from working perfect to super stiff. Is this a known issue?
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