Master Divider build/testing puzzle

[whomper]

Hi,

Just finished building the master divider and after powering it up, it behaves in a strange way.

Out of the 16 steps, about half of them contain a constant 4.5v signal and the associating LEDs are lit. The steps are 1,2,5,6,7,10,11,12.

No input signal changes the above, it is like the module is stuck.

[andrewF]

[whomper]

Certainly,

They "always on" parts are: 1D, 2A, 2D, 3A, 3D, 4C, 4D, 1A. (1,2,5,,6,9,12,13,14 and not as I originally stated).

The rest are "always off".

It does not matter if I inject something in the input, the situation of the always off and always on does not change.

I have the HCF4024E and the HCF4070BE.

Testing with a multimeter the outputs of the 4024, I am getting a clock in pin1, some voltage out of pin6, 15V in pin 14 and nothing else.

Might be a problematic 4024?

[andrewF]

Well it looks like your 4070s are okay, the leds that are on, should be on when they are not being driven by the 4024.
I guess the voltage on pin 6 is quite small? if it was over 2V or so, 1A's led should be off.

Check 4024 pin 2 is 0V.
Check 4024 pin 7 for continuity to 0V (beep! test)

Have a good look at your soldering.

If it all seems good, try another chip. The HCF4024 are suitable for this cct. (Not 74HCF4024 tho).

I think it is best to blame the chips after testing everything else...maybe cos I rarely use sockets and hate de-soldering chips .

I just looked the 4024 up in my CMOS sourcebook (Braga) and they show it as having 16 pins! Must be a special edition. Excellent book otherwise.

[whomper]

After a short email with Ken I understood I kept both the link from 4024 to 4070 as well as applied the patch to connect them.

Removing the link from the silkscreen side resolved the issue.

Thanks!