20b display problem



#6

I've got a 20b with a display problem. Some of the pixels don't go dark.
Anyway, I've opened it up and have located the problem. The zebra strip connecting the main PCB and the display has detached at one end (two tracks maybe three are broken). If I press down lightly, the display comes good.

Do any of the restorers have a suggestion as to how to reattach it?

- Pauli


#7

The 20b should still be under warranty. Try to contact HP or your dealer.

#8

hello,

contact 1 800 HP INVENT and get your product replaced under warranty.

Else, use no melt solder tape and place it on the strip, then use a soldering iron to re-heat glue the strip on the contacts.

cyrille


#9

I don't think that phone number will help in Australia (although I did buy the unit from the US).

I'll try the solder tape.

This one is somewhat sacrificial: I've drilled out the four plastic mushroom rivets so I can get to the keys and relabel them :)

- Pauli

Edited: 16 July 2009, 6:40 p.m.

#10

Fixed the problem.

Examined under magnification, the problem is the end conductor or three on the Zebra strip hadn't seated down properly. The obvious solution is to re-melt it in place.

Then the complication, the unlike other such strips which solder fairly nicely, this zebra strip melts instantly on contact with a soldering iron and by the time I'd figured this out, it had melted past the end of the PCB. Not to worry, a short piece of solid wire can be placed on the pad on the PCB in such a way that it pokes into the zebra strip. Solder the wire to the PCB quickly and the heat imparted to the wire seems to melt the zebra strip in place. In fact, the wire ended up poking through the zebra strip. Be careful here or you'll melt the adjacent conductor on the zebra and the process will have to be repeated. When done and verified, cover the whole thing with a generous blob of epoxy -- I used 90 second Araldite but any should work.

If you're very quick, it is possible to lightly tap the zebra at the bottom most end with the soldering iron and this will melt it onto the pad okay, you do have to be very quick though.

I don't know if this has been mentioned before or not, but the 20b runs fine on one battery.

Now to figure out how to best re-label the keys and attach the debugger pins.


- Pauli


Possibly Related Threads...
Thread Author Replies Views Last Post
  HP's thinking behind the 20b/30b? John Ioannidis 3 702 09-07-2013, 10:21 AM
Last Post: Tim Wessman
  HP-41c display problem Ignacio Sánchez 6 989 09-04-2013, 10:52 AM
Last Post: Ignacio Sánchez Reig
  20b, 30b not in HP's web store Eric Smith 3 673 02-08-2013, 11:52 AM
Last Post: Walter B
  Can the display for a HP32Sii be replaced with the display from another model? Bruce Larrabee 8 1,203 10-10-2012, 10:05 PM
Last Post: Luiz C. Vieira (Brazil)
  A non 20b/30b 34S Matt Agajanian 22 2,037 08-20-2012, 01:06 AM
Last Post: Reth
  HP41 Display Problem Fouad M. Kaadou 3 659 06-29-2012, 07:46 AM
Last Post: Fouad M. Kaadou
  [WP-34s] IR conversion of 20b Alexander Oestert 3 658 05-18-2012, 05:38 PM
Last Post: Harald
  Sharp PC 1211 display change -- problem overnight -- suggestions? Gene Wright 12 1,347 05-16-2012, 03:31 AM
Last Post: Bart (UK)
  HP 34C display problem james summers 11 1,464 04-05-2012, 06:07 PM
Last Post: james summers
  Why hp-20b more expensive than 30b? Masaki Adachi 9 1,230 10-14-2011, 12:08 PM
Last Post: megarat

Forum Jump: