HP-65 1333A18516 - [SOLVED] request for advice

[albertofenini]

(06-17-2024 02:06 AM)teenix Wrote:  Hi Alberto,

I'm not sure exactly what I am looking at, but obviously all signals are not present on the faulty unit, so I am wondering if the anode driver failed. That doesn't really explain why the signals ABCDE from the hybrid are not there though unless the anode driver is loading them down.

1V on VCC seems low for some reason, I suspect it would be higher on a working machine. I cannot test anything to clarify results, I was forced to move a few days ago and doing anything at the moment is rather difficult.

Does the anode driver get warm in use?

cheers

Tony

Hi Tony, thanks for your reply,

no IC get warm when the calculator is turned on,
also don't look at the values we posted in the previous messages,
you need to look at the values we posted in the pictures galleries, are those named
Voltages and Tensioni (Italian for Voltages) the Vcc and the Vbsw are all there and correct in both units

But you are right, the faulty unit has not RCD, not Step in, not step out and no signals at DISP0 - DISP4

Our guess is that a shortened trace put everything down, let's hope this has not fried anything as
the Anode and Cathode drivers from the donor were perfectly working before the transplant

Also, we soldered the Anode driver and cathode Driver originally from this board (1333....) back into
the donor board and they where not working, but this doesn't prove anything

Will be away for a week or so, in the next steps we will remove the Anode and Cathode drivers
and we will inspect the traces underneath , also we will check if with the Anode and cathode drivers
removed the signals at the logic board will get any better

We'll keep you posted on this
Take care and thanks for the support