HP-65 1603S03504 - restoration project advice needed

[albertofenini]

Hi everyone

this is our last restoration project and is still on going
Unluckily this unit has been tampered and the back label drilled in order to open it ...

Also, the upper half of the case has been damaged, hard to say how and with what
but very badly damaged.

We have detached the keyboard faceplate and swapped the case with one of a non
working HP-67, coated the faceplate and cleaned the keys.

So far so good.

The card reader has been badly rebuilt so we will take care of that later, as it also
shows bits of oxidation and one of the magnetic head cables was loose, so we will
rebuild it from scratch.

However, when we powered the calculator with a battery pack it showed no signs of life other than
the card reader IC Amplifier that was getting pretty hot.

We have disconnected the card reader and even removed it physically but it didn't
change at all.

On the display board we have seen that one of the inductances was replaced, as they
are of different colors although of correct part number, and looking at the power
cables the soldering joint were way too fat ...

Also some of the led soldering joints have been re-done as they are more shiny ...

The logic board on the other side and luckily works very well when put in a
different unit.

We have a spare led board but we would like to learn how to trouble shoot this one as
well, can anyone gives us a couple of ideas on where to start from ?

Thanks a lot !!

Pictures : HP-65 1603S03504 - restoration project advice needed