Repair and Re-build of SE Labs SM 112 Scope

[Geaney]

I spent a few hours on this over the weekend without much luck. The trigger control is just a pot across two dc rails so provides a simple DC bias to a long tailed pair - one end of which is fed with the trigger signal. When set to EXT there is a signal there but not when set to CH1 or CH2. When I followed the wiring back to the Y amplifier section I had great difficult finding any signals - though all the dc applies are there for sure. However the signal must be getting through as it displays on the CRT!

At this stage I am somewhat embarrassingly reduced to RTFM. I'll spend some more time reading before I try again.

I was making video clips along the way but it seems pointless to post until I've made a breakthrough - which might be a while yet!

Cheers, John