Tek 180A update :So, now the next defective stage as I said last night, is the 1s stage, which exhibits the same symptoms.
so of course I checked my film cap but here it seems to work fine : I do get my charging exponential, with good amplitude, on its relevant pin.
So the source of the problem must be something else.
OK I have fixed that 1s stage, was quick.
As I said a few minutes ago, my home made film cap was fine this time.
So I checked the output of the cathode follower taht feeds the front panel.
Signal was THERE, and 100% good.
So it was a switch or wiring problem for sure.
Some LED torch lighting later, found the wire broken off at the solder joints at the back of the relevant switch. Not easy to see because wire is so stiff that even with its joint broken, it was still "hovering" half a mm above the joint just fine, giving illusion that it was still connected....
Access to the switches / back of the front panel, is not great because the hinged deck as I said earlier, does not open fully. I had to get it do just that though, or else no way I was going to be able to fix that broken joint. So I unhinged the panel, and also had to desolder a lone wire attached to ut, that was coming from the main deck.
Then, I had decent access and could fix that joint.
I now have my 1s markers available on the front panel just fine
![Cool 8)](https://www.eevblog.com/forum/Smileys/default/xcool.gif.pagespeed.ic.cOxV6sPNRd.png)
So, there is only ONE stage left now !! Getting there !!
The 5s stage. It does..... kinda... work, but not fully.
It does produce nice markers, but the time interval is not correct. Trim pot has no effect it seems. All I get is an interval of 2s instead of 5.
Two seconds is not 1s, so know right there that the monostable IS doing something, as it's skipping one in two markers from the preceding stage.
So there is monostable action going on here, just not enough of it.
So prime candidate as always is a RC network that's too low a time constant to block 4 pulses like it should. Can only block one.
So again check the value of C and R.... stay tuned !!!
![Grin ;D](https://www.eevblog.com/forum/Smileys/default/xgrin.gif.pagespeed.ic.QVVz6XIT20.png)