HP-65 1333A02242 display missing all the decimal dots

[albertofenini]

Hi Tony,


To which attached image are you referring ?

It should be at bottom of last post.
I have added a tag to each of the snapshots, they are labeled
Step
Disp4
Disp3
Disp2
Disp1
Disp0
Segmento a
Segmento c
Segmento b
Segmento d
Segmento f
Segmento h
Segmento e
Segmento g
I'm assuming you are referring to Step, right ?

CLx just clears the display and allows a new number entry, then pressing the DP button should result in just the decimal point showing.
We didn't hit CLX during the measure, all of the snapshot were taken with a 0.00 shown.
Don't know if this helps

You meant the 18th pin right ?
My applogies, yes.

We are in difficulties comparing our waveforms with yours and understand if ours are correct or not. What scale for the time and volt you suggest ?

For viewing a full display refresh, 2V per Div and say 40uS per div should be ok, triggered on the RCD pulse if you can, so you can see everything in a display refresh.
Will try, remember we didn't post RCD waveforms

You say that we should see 15 pulses ... in the STEP image we uploaded we see 4 square waves and noise in between
The first square wave is a little more distant of the following three, is this what you mean ?
Four is because 0.00 in theory is 4 digit ? (the 3 zeroes and the digital point ?)
Should we lit all the display digits to see the 15 pulses ?

I was pretty sure that all 15 pulses should be there regardless of how many digits are being displayed. Have a look at page 15 of the Classic Notes, it shows a HP-65 waveform.
We surely will, but just to understand with pulse you mean what we call a spike ?

(The DP coil might be open circuit as well.)
Any way we can check that too ?
From the common coil terminal to the DP coil terminal should measure low ohms. I think this should be between VBsw and pin 18 of the anode driver. VBsw is the switched side of the battery, 12th pin in from right of cpu to keyboard connector
You mean that common coil terminal is Vbsw ? I have seen that is also available
as the 11th pin of the Anode driver, can we use that ?

Thank you so much !