HP 67 Repair Person HELP WANTED

[jftman]

I have a HP 67 that I did the O Rings and exchanged the positive battery contact.
There was oxidation but the traces and boards were undamaged.

An ‘untested’ purchase.
The chips look like tge smoke is still in them. LOL
When I use a battery pac, woth and without a wall charger the display flickers in several areas but only a pixel here a pixel there and only a hundredth of a second.
Just to say, yeah I’m switched on.

I put a DC power supply across the terminals and all I can get is the low battery led in the lower right corner. It too doesn’t always light.

My hope is that someOne with an oscilloscope knows where to trace power delivery to narrow down a routine power problem, or locate a defective component.

Tony has been nice about sharing info.
Being in Australia is not a hugh barrier, but I thought I would ask on the chance that another member wants to look at this and repair if so……..PLEASE PM Me.

Pics are calculator OFF then ON

I live in Western NY.

[John Garza (3665)]

Well... based on the pics, 3.13V is too low, and 5.11V is too high.
Try 3.8

...and if that's not the issue, clean for corrosion even if you don't see it. Even a slight layer can cause trouble. If it's still not responsive, I'd swap out the logic board with a known good one to narrow down the location (logic board vs. keyboard traces, faulty switches, loose wires, etc.)

-J

[jftman]

I am hoping a member here who lives in the USA would agree to let me mail this for trouble shooting and possible repair.

The two photos shown are the supply display once the calculator was switched on with the initial 5v setting.
I can certainly try 3.8v in the same way.

[mbielman]

I PM'd you. Hope that actually works!