Repairing my HP 67 Twins

[murphy9]

I decided to update and recondition my two HP67's - both originally worked except for the card readers (of course) - one is fixed and working though I did damage the connector pin from KBD to Logic board. So my quest is to find out there's a source for the these connector pins so I can restore the device to it's full former glory. Does anyone know if there is a source of these pin connectors I want to avoid hardwiring with ribbon cable [yuk!].

Also is there a source for someone providing the metal rear labels mine are on the cals, but bent and not pristine.

For the second one I'm thinking of upgrading to an HP-67E from Panamatik (because, why not).

Thanks advance if anyone has any links to the pins.    

[teenix]

These pins are not manufactured anymore so they have to come from a suitable donor.

I can post a couple unless someone is closer.

cheers

Tony

[Hiwi]

How many do you need?
Are they broken or only bent?
I can send you some from a donor HP.
Ralf

[murphy9]

You guys are awesome - I'll reach out to Tony as I think he's based in Australia like me. Only one is damaged - it's bent but my worry was that it might snap if I 'correct' it. I'll reach out in a few weeks when I start on that device if it snaps.

[murphy9]

Thanks to all for reaching out .

As a side note to anyone cleaning/restoring the keyboard plate, be very carefull with which solvent you use to clean. I used my go-to isopropyl alcohol and was left with a white deposit. As the isopropyl alcohol is 99.99% pure I can only assume that the deposit is the original lacquer or coating on the plate. Luckily I was able to get rid of most of it with cotton bud and water with a tiny drop of washing liquid. Applying five coats of Tamiya TS-80 has levelled the surface, removed shiney artifacts and left the surface beautifully smooth and flat (I've enclosed a shot).

The mag reader works but I'm getting an error, so will need to jump into more detail on that and probably change the capacitor. Gummy rings replaced last year so the cards feed well.

waterhosko's battery back holds up well and charges nicely from the PSU.

Getting time to do all this is the issue - so slow project.

[teenix]

(11-08-2023 12:27 AM)murphy9 Wrote:  You guys are awesome - I'll reach out to Tony as I think he's based in Australia like me. Only one is damaged - it's bent but my worry was that it might snap if I 'correct' it. I'll reach out in a few weeks when I start on that device if it snaps.

Yep, down here in Melbourne.

With regards to the face plate, I only use dish washing liquid in warm water to clean it, and then only a light rub with a soft sponge so as not to accidently remove then printed characters. That's followed by a warm water rinse and a soft cloth pat dry. It seems to work ok.

cheers

Tony

[Mike T.]

Very nice job!

[murphy9]

I've got both running and the red LED plastic filter polished on the inside using Autosol Acrylic Polish (we have this in Bunnings (Home Depot equiv) here in Australia but I also remember it in the UK) - used a cotton bud and cotton wool to remove the cloudy finish and buff it up to new. Both calcs displays are now like new and the previous cloudiness has gone.

Both are charging the Nicad.

The next hurdle is the Card reader. Both had gummy wheel repair a few years ago, both feed the cards in but...

"Twin one" will feed original cards through but displays an 'error' every time.

"Twin two" can store programs on a new card and retrieve that program, but won't read original HP provided program cards which came with the HP-67. My HP-41c card reader can read both the new and the originals.

The motor speeds 'sound' slightly different for each of the Twins, but no indication of clutch issues etc.

At this point I'll need think about deeper visual inspection probing with a multimeter, and then possibly use this as an excuse to invest in an oscilloscope after the christmas break.

Question - is it worth just replacing the capacitors first as these are normally the things that go after 50 years ;-) and if so what are the best replacements ? I know the values etc, but there are too many versions of each (and sizes etc). There's no sign of electrolyte leakage, but these things are close to Tutankhamun's age.

Finally - I have bought all the latest CD/DVD/USB from the [tremendous] community over the years, but only seem to have the HP97 service manual in pdf - can someone point me to one for the 67?

Thanks again !

[jftman]

I have learned some straightening methods doing watch repair. Pivots are very easy to break if Re straightening is tried.

I am not exactly knowledgable of the size and shape of the pins you reference. I myself just bought a HP67 and it isn't working so I want to learn from others!

Watchmaker tweezers come in many types. You might find a solution by getting a pair that are fat and wide jawed. The idea is the extremely flat and parallel tips You would warm them up then let the heat transfer to the work and with this you can straighten stuff.

If you have a hollow pin or ‘cylinder’ a set of pin gauges are handy to insert into the little hole, to not collapse anything. Pin gauge sets for watchmakers are graduated in 0.02 mm typically. Two hundredths of a millimeter.

[murphy9]

These are the pins that provide connection from KBD to Logic board and Logic Board to Card Reader drive. They're normally a very good way of connecting the boards, but in repairing I suspect that they can eventually snap. I have managed to rebend the one I bent, but not sure if that specific pin will now be a potential 'point of failure'. See the image of the pins (not my one).

I'd hoped that somewhere they was a huge stash of these that we could draw down from if needed, but it looks like we'll need to draw from a few kind folks who have ones recovered from damaged parts.

[murphy9]

Next stage is replacing the backplate on the 67's. These are bent and I thought I'd be able to create a similar version using Photoshop, 1200 dpi and proper fonts etc ie vector [rather than a bit mapped version]. It's a pretty good match and I've experimented with a few routes to get this printed.

First off I've used a Laser to do B/W image on paper and sprayed with Tamiya TS-80 to create a protective later. This worked okay-ish but the paper would curl if sprayed too much. So I've used one image in the centre of the paper to provide structure when applying the layers and I'm applying very thin layers, each over a few days, in order not to stimulate diffusion of the ink into the varnish or 'wet' paper. Seems to work so far, though if too many layers applied too soon then the ink fades and the surface goes a bit cloudy. See the images included.

Whilst the final to date actually looks great - as it's not metalised I'm looking for a decent silver foil at A4 size to try the next phase - if anyone knows of a thin silver metalised foil that can hold laser print images and then be varnished with TS-80 then I'd be interested in tying that.

I tried laminating but the image is quite solid (black) so doesn't laminate as well.

The images included show the effect of too much spray on the left and gradual build up on the right - looks pretty good to me - also hoping there are no typo's.

[teenix]

If you can get similar thickness aluminum foil, you can get quite thin adhesive backed matt finish laser (preferred) or inkjet transparent print film that can adhere to this. You can print these in a negative format so that the background is black and the letters, lines etc are see through, showing the underlying foil.

I used to use them to make front panel labels for electronic projects which was some time ago, but I can't remember the name. Ther background could be colored in sections to give different text colors also.

If it is suitable then some adhesive on the foil rear should complete the job.

cheers

Tony

[ishe]

Hi,

My HP 67 calculator has the same issue, I have 3 broken connector pins. Can someone help me to find them from a donor?
I am in Hungary.

Thanks
Istvan