Telequipment DM64 'scope help with missing X scan

[boater sam]

I will PM you, what a smashing chap you are.
Sam.

[Refugee]

Looking at the mapping of the switching is mind numbing and I am afraid that looks like what needs to be done.
I have been tackling the switching on a Tektronix scope that has some timebase ranges missing. It is a frustrating job and this last week I have been doing the garden and have been off the job but will be back soon.

[boater sam]

I know only too well what you mean. There seems to be no logic as to where components are located, no physical diagrams, no labeling of switch layouts.
I have been trying to find my way around this DM64 for 5 days, each worse than the last. No access to some boards at all, odd components on the backside, and thin poorly attached connecting wires.
I remember the valve Tek 'scopes and they were nothing like this horror.

[boater sam]

Finally got my act together and took a trip to Mark Hennessy with teh dreaded DM64 and a DM63.

A few hours on the bench with some of Mark's decent test equipment and his great depth of knowledge established that the '64 had eht way too high due to high resistor values and low 14v rail for the same reason.
Got that up and running well, I just have to put it all back together, its guts are hanging out at the moment because its the only way to get access to some parts.
The '63 was a little difficult, led us on a little dance for a while but Mark likes these and it succumbed eventually. Similar problems with resistors going high.
So now I have 2 working 'scopes in pretty good order, thank you Mark. Hope I didn't deplete your component stocks too much or disrupt your household. Please thank your wife for me, the coffee kept me awake.
Took a side trip whilst down south to Steven Ostler's and collected a pile of old valves, thank you Steve,
which I will get sorted and listed so that any member that needs a few more can let me know and I'll post them off.
All in a long but interesting day, very productive and enjoyable. 

[Mark Hennessy]

It was a good day; both 'scopes gave us a run for our money, but we got the better of them!

It was also great to meet with Steve and a handful of other folk from the vintage scene. I managed to come away almost empty-handed, but I couldn't resist the offer of a lovely Roberts RIC2 that is in remarkable condition under the dust. Also, Sam left me with a spare DM63 CRT, and with any luck it'll be better than the one I have in my restored DM63 - I'd given up all hope of finding a replacement CRT for that one, so that's very exciting

As I say, a good day

[boater sam]

Just to add for Mark's benefit, I got the timebase switch assembly back into the '64 and ensured that the board had a ground! The scope is working, done a 3 hour soak test and all is well.
I leaned on the DM63 which was also on a soak run whilst straightening out the Z connector on the back. Tingles! Oops, 117v to earth! No earth continuity in the mains lead.
Now I have had this before with unusual Tek mains plugs. The spring in the socket eases with use. It takes a slight crush of the rubber moulded plug-in to restore a contact.
I hope that tube proves to be a gud-un, I will never need it and you do have a soft spot for DM63s. After all that clever design replacing the special Tek IC with TTL it would be a cop out to put up with a low tube.
Thanks once again, it was a smashing day.

[Mark Hennessy]

Now that is interesting! I did occasionally notice a "click" from the test speaker connected to my 'scope when connecting its croc-clip to the chassis of your DM63, but never stopped to think about it. Of course, some times, it was getting an earth from other test gear, so it didn't always do it. I don't recall any tingles. But, it just goes to show

As soon as I try it, I'll let you know about the CRT. I really should be doing other things this week, but I suspect I'll give in to temptation before much longer...