HP-67 Keyboard Domes

[BillBee]

Hi Guys,

I had a nice caveat emptor moment with a HP-67 I acquired for parts. As with a 41 I have had a red LED fascination.

The plan was to find a 67 and just pop one of Tony's boards into it. I really did not mind if the card reader was functional. I knew from the label it was opened and was being abandoned but looking for a shell I was fine with it.

Everyone gets lucky now and again so I popped a battery in and with a flash of a red light (lower right corner) the card reader started and would not shut off. Time to take a look inside as gummy wheel gunk can stick to many places (based on 41 reader observations) perhaps with the reader turned off I could see if the board was good.

and...….

Ouch. It was opened and the lower two rows of key domes were gone.

Options? Is there a way to "turn off the card reader sensor"? I have a feeling if there was any life in the main board it will not show if the reader is spinning like a madman.

Key board domes.... based on what I read a parts donor - 45, 35 or that series is the limited option available? Fear not only a dead one would be used.

I have no issues with the guy who sold it BTW as it was my case of risk/reward.

Thanks!
Bill

[teenix]

You can remove the red and black power wires and take out the card reader board. The red and black wires will have to have their ends insulated so they don't short anywhere, or disconnect them from the charge connector as well.

I have limited experience with the key strips, but if they look the same, they should work the same. They are spot welded in place and can tear and distort if you try to lever them off. Drilling with a small drill would be a better option but only drill to the point that the strip releases from the board, not through the board or you risk drilling into a circuit track. They can be soldered back in place with multiple points available on the circuit board (from memory) but they need to be flat and even on the board surface. If they are not secured properly between the domes, then the strip will distort a bit when a key is pressed and the key will feel mushy. As you may not be able to mount them as securely as original, that may be the case anyway. Glue may help here.

You need to make sure the strip has a good electrical contact to the circuit board tracks that it was originally connected to or the row of keys may not work.

Carefully look at the replacement strips and make sure there are no cracks on or around the domes.

cheers

Tony

(07-23-2021 06:57 PM)BillBee Wrote:  Hi Guys,

I had a nice caveat emptor moment with a HP-67 I acquired for parts. As with a 41 I have had a red LED fascination.

The plan was to find a 67 and just pop one of Tony's boards into it. I really did not mind if the card reader was functional. I knew from the label it was opened and was being abandoned but looking for a shell I was fine with it.

Everyone gets lucky now and again so I popped a battery in and with a flash of a red light (lower right corner) the card reader started and would not shut off. Time to take a look inside as gummy wheel gunk can stick to many places (based on 41 reader observations) perhaps with the reader turned off I could see if the board was good.

and...….

Ouch. It was opened and the lower two rows of key domes were gone.

Options? Is there a way to "turn off the card reader sensor"? I have a feeling if there was any life in the main board it will not show if the reader is spinning like a madman.

Key board domes.... based on what I read a parts donor - 45, 35 or that series is the limited option available? Fear not only a dead one would be used.

I have no issues with the guy who sold it BTW as it was my case of risk/reward.

Thanks!
Bill

[BillBee]

Thank-you Tony. I will go slow and be careful.

-Bill