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What's the best way to re-assemble a Voyager? - Printable Version

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What's the best way to re-assemble a Voyager? - jbssm - 08-24-2011

Hi all,

so my HP-15C keyboard was in a really bad state and in whim of youth I decided to take it apart.

Now, the good news is that it was only dirt as I expected. The bad news is that I have to put it back.

I kept all the plastic pin heads I cut to reach the keyboard, and has I recall seeing somewhere in this forum I tried to put it back by melting them with my soldering iron.

That doesn't work. When I try to heat them, they get all shrunken and they do now mend with the rest of the pin back at the calculator.


So, are there any other ideas to put it back? I tough about using a strong glue on the pin heads. Has anybody tried that?


Also, there are some small scratches in the keyboard metal part (the black one), do you recommend some painting to cover it with a brush?


Re: What's the best way to re-assemble a Voyager? - Artur-Brazil - 08-25-2011

Hi,
I have done this to many calculators:
You'll need:

- a 10 or 15 minute liquid(gel) epoxy glue; it is sold in two parts; it doesn't get spread too much, as it is a gel and is of fast cure;

- around 10 to 15 small pins that you will put over the pcb. They must have around 1cm heigth (all same height!!!) and less than 1cm in diameter; you will put them over the pcb, between the holes where front part plastic pins come accross of;

- a small piece of wood or other plan material (15x20cm); you will put it over the pins;

- some heavy material, around 2 or 3kg. You will put this over the wood;

Procedments:
- put the front part with keyboard down on a table;
- insert the pcb on it - so, the plastic pins of front part will arise by the holes on pcb;
- prepare some glue and quickly deposit small drops on all the holes where the plastic pins of front keyboard arise - don't spread them - the epoxy will spread by itself over and tight front part pin to pcb;
- put the small plastic pins you got over the pcb, between the epoxy drops (but not let them be glued to pcb);
- put the piece of wood over these pins;
- put the weight over wood and let there for one hour or more;

See the schematic, as my English is very poor:

   XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX        WEIGHT
======================================== wood
|| || || || ||
== || == || == || == || == || == glue and plastic pins
-+-----+-------+------+------+------+- pcb on the place
| | | | | | plastic pins from front
======================================= calculator facing down

Please, do not use an extremelly heavy weight to press everything, as you would bent the front part and pcb.

At the end, you'll see you HP with a tight keyboard as new!!

Need to clean the alummium bezel? Use a soft sand paper and after removing scratches, apply a lacqueur.

My best wishes!!!
Artur - Brazil

REPLACE THIS TEXT WITH YOUR LISTING
[/pre]


Edited: 25 Aug 2011, 2:45 p.m.


Re: What's the best way to re-assemble a Voyager? - uhmgawa - 08-25-2011

Quote:
Hi all,

so my HP-15C keyboard was in a really bad state and in whim of youth I decided to take it apart.

Now, the good news is that it was only dirt as I expected. The bad news is that I have to put it back.

Before you put the shebang back together I'd recommend
rotating the tactile dome strips between the more
frequently used keypad locations and those of lesser wear.
You did mark from where each tact strip originated of course?
Yea I forgot enough times too but you can detect any wear of
substance by tossing a strip on a ~200gram scale and measuring
any differential dome inflection force.

Quote:
I kept all the plastic pin heads I cut to reach the keyboard, and has I recall seeing somewhere in this forum I tried to put it back by melting them with my soldering iron.


I can't imagine that method resulting in a successful re-staking
comparable to the original post heads. Besides needing to
replace the head you need to do so under controlled conditions
of temperature, pressure and time. There is also the
consideration of the overlay elastomer membrane which should
be (and was) compressed in the original staking operation.
Rather than rebuild the posts to subsequently heat deform,
I've just cut new head blanks from 1/8" ABS welding rod on
a lathe to solvent weld one-by-one onto the beheaded posts
under pressure. (A sharp set of diagonal cutters with jaws
flat on one side may work too.) It is a bit slow but will
result in a joint of far more substantial strength compared
to having at it with an (over temperature) iron.

You may want to use a solvent cement (with filler) such as
ABS pipe cement vs. say, acetone and apply it to only the new
head blank and not the target post. Doing so will minimize the
likelihood of creating a bond between post and PCB which will
frustrate any future disassembly attempts. A jewelers loupe,
tweezers, and hypodermic syringe for dispensing the cement
will go far to insuring a neat job.

Quote:
That doesn't work. When I try to heat them, they get all shrunken and they do now mend with the rest of the pin back at the calculator.

The posts were likely (or should have been) cut flush with the
top of the PCB such that they are the correct height to
automagically gauge the reassembly pressure. If that isn't
the case or they are further deformed by an attempt to rejoin
the cut heads with an iron you may have some experimentation
ahead. In any case cut a piece of stiff foam (eg: carpeting
base) to fit just inside of the external keypad area which
clears the upper display bezel and right/left housing. Put
the calc face down on the foam (posts pointing up) and using a
small drill press with a bit mounted backwards in the chuck,
apply pressure to the head+post to be rejoined. A weight
hung on the on the quill handle will help achieve consistent
joints. ABS solvent-based cement will set sufficiently such
that joint pressure can be removed in a few minutes depending
on type of cement and amount applied. If this procedure is
followed carefully the PCB should be removable (and restake-able)
as above for subsequent repair.


Edited: 25 Aug 2011, 3:16 p.m.


Re: What's the best way to re-assemble a Voyager? - jbssm - 08-29-2011

Hi Artur (I send the messa in Portuguese bellow in case it's easier for you),

So, today I was finally going to do it but I got stuck in a part.



You say I should use pins with 1cm heigh and about 1 cm diameter. But if I use pins with 1 cm heigh they are too big and I will not be able to put the back part of the calculator back.

Can you explain better?



Thank you.



------------

Agora em Português.


Olá Artur,

hoje ia finalmente tentar usar o seu método mas fiquei empancado.



Você diz para utilizar pinos de 1 cm de altura por 1 cm de diámetro, mas se tiverem 1 cm de altura são muito altos e não consigo pôr a parte de traz da caixa da calculadora de volta.

Podia explicar melhor o procedimento, é que talvez eu não esteja a entender bem.


Re: What's the best way to re-assemble a Voyager? - Didier Lachieze - 08-29-2011

Here is a an example with some pictures:
Fix the keyboard of a HP15c


Re: What's the best way to re-assemble a Voyager? - jbssm - 08-29-2011

Thanks Didier.

Can you explain me where do the needles get fixed? I mean are their inserted into the pastic of the keyboard (that doesn't sound very tough) or in some other method?

An can you suggest any other material for a needle? I don't have a spare microprocessor at home, so perhaps some copper wire or similar?