HP65 card header read/write head

[NoEqualsButton]

After several more frustrating attempts at getting the HP65 card reader going, I am happy to announce it is working for now. There are still some issues I'd like to revisit but while it's working I am reluctant to touch it again right now.

One of the problems I had during the repeated assembles and disassembles was the five very fine wires connecting the read/write head to the "guitar" PC board kept breaking off at the board. Stripping the insulation off these to resolder them back was a very delicate job and it's very easy to break the conductor, which I did numerous times. The end result is the wires are only *just* long enough to reach. One wire in particular ( the red one ) just could not reach and I had to resort to adding a short length of wire to complete the connection. Far from ideal, but it works for now.

Has anybody else had this problem? I think next time I get the hood off I want to replace those 5 wires with a short length of ribbon cable - do a proper job. I've have taken lots of close-up photographs so I know where the wires are supposed to join onto the "guitar" board.

Very happy to have this beautiful machine fully operational. She's the flagship of my collection now.

[[kby]]

(08-23-2019 05:05 AM)NoEqualsButton Wrote:  Has anybody else had this problem? I think next time I get the hood off I want to replace those 5 wires with a short length of ribbon cable - do a proper job. I've have taken lots of close-up photographs so I know where the wires are supposed to join onto the "guitar" board.

Yes.

Some of the (later) versions have connectors soldered to the board into which you push the (tinned) wires into (more commonly also used foe the power connections to the main logic board). I can’t recall the name of those connectors, but someone asked about them in the pas year wrt the power ones (and i’m Sure someone with a better memory than me will chime in with either the name, link to the post, or both). That keeps the wires from breaking off, but those connectors don’t take frequent removal/re-insertions and maintain good contact, so it doesn’t really solve the problem;lemme although it helps some.-kby

[teenix]

(08-23-2019 05:05 AM)NoEqualsButton Wrote:  Has anybody else had this problem? I think next time I get the hood off I want to replace those 5 wires with a short length of ribbon cable - do a proper job.

I don't know if ribbon cable will suffice. At the circuit board maybe, but it's usually pretty thin and may not pass the current for the motor, plus the ends will have to be pulled apart quite a bit to run to the motor, battery and ground.

Light gauge single strand hook-up wire would do, similar to the original wiring. Heavier gauge wiring might rip the small solder pads from the circuit board.

cheers

Tony

[NoEqualsButton]

(08-24-2019 11:36 PM)teenix Wrote:  I don't know if ribbon cable will suffice. At the circuit board maybe, but it's usually pretty thin and may not pass the current for the motor, plus the ends will have to be pulled apart quite a bit to run to the motor, battery and ground.

Light gauge single strand hook-up wire would do, similar to the original wiring. Heavier gauge wiring might rip the small solder pads from the circuit board.

cheers

Tony

The power wires are securely soldered to the board okay. It's the five wires that connect the read/write head that have the problem. I have reconnected them but I am not convinced the connections are secure since every time I remove that "guitar" PC board one or more of these wires breaks off the board.

I think your idea of using single strand hook-up wire is a good one, ribbon cable will be too heavy, plus it's got to fit into a tight space. The real trick is stripping the insulation without breaking the wire.

[NoEqualsButton]

(08-25-2019 01:40 AM)NoEqualsButton Wrote:  The real trick is stripping the insulation without breaking the wire.

I'm googling wire strippers but don't have any idea what gauge this wire is. I'd guess 34 AWG. Does anybody know the exact gauge? Trouble is professional tools like this cost more than I paid for the calculator!

[teenix]

(08-25-2019 02:24 AM)NoEqualsButton Wrote:  

(08-25-2019 01:40 AM)NoEqualsButton Wrote:  The real trick is stripping the insulation without breaking the wire.

I'm googling wire strippers but don't have any idea what gauge this wire is. I'd guess 34 AWG. Does anybody know the exact gauge? Trouble is professional tools like this cost more than I paid for the calculator!

Maybe Jaycar - Par No. TH1824

cheers

Tony

[NoEqualsButton]

(08-25-2019 03:33 AM)teenix Wrote:  Maybe Jaycar - Par No. TH1824

cheers

Tony

I actually have one of those. Not sure the tension can be wound down far enough, but it's worth a shot. Maybe find some similar gauge wire to practice on first. Thanks.