Tektronix 468 repair/refurb

[cd_edwards]

I've narrowed it down to a couple of transistor's in ch2. everything before that point is the same as ch1 with voltage and waveform. At this pair of transistor's, the voltage is normal on b and e but the c is 1.7v instead of 2.7volt. This is the Q212/214 pair of NPN transistors. I've attempted to check the components in the filter between them, but there are differences between what I have and what the schematic shows. (I'm missing some components). I don't want to play around with the gain however, as the voltage on the base of this pair is exactly what it's supposed to be along with the correct waveform. Its definitely, in the filter I just need to figure out where. attached to the collector is a 300ohm resistor with a 470 capacitor. I'd have to assume that's a 470pf. I am testing before them, so I believe they are ok.

[Addicted2AnalogTek]

I know these old analog scopes take a little time to warm up, but I have never heard of the PSU waveforms being crap on startup - especially not like they just were. 

Anyone out there that can shed a little light on this matter for me?

I wouldn't stress too much about it, unusual as it sounds. Remember there is usually a stated time in the Service manual that the scope must be running for before accurate measurements or calibration procedures be commenced. This applies to all scopes, CRO's and DSO's.

Curiosity might make me monitor power-on mains currents accurately or just with a dim bulb tester.
Are the same rogue waveforms produced at re-power after the scope is warm?
It does sound unusual. 

Even though this thread is abandoned, I feel the need to post a quick update here. 

I had set this specific 468 off to the side and moved on to another 468, 485, and 465 until I found some information that may help me solve the main issue with this 468 - the power supply waveforms and their erratic behavior.   

As it turns out, the problem was a faulty 110v rail bridge rectifier. It wasnt bad enough to cause half-wave rectification, but it was doing exactly what the bad rectifier that Dave found in one of his (fairly recent) repairs - it was randomly dropping out and blocking the flow of current. This is what caused the 'jumpy' waveforms all over the PSU.  The 'rounded off' falling edge of the PSU waveforms were caused by the 55v rail's filter cap, which began showing a slightly high ESR after several hours of the scope being powered on.

The rectifier is replaced and the new filter cap (not the one borrowed from the other 468) is on it's way from Greece.