Telequipment D43 trace wandering, panicky

[ChrisGadg]

I cleaned up an old oscilloscope, a Telequipment D43. The Type A amplifier in the top bay is OK, but the type C-2 amplifier in the bottom bay has a loose connection somewhere or has other deterioration.

I put a video of it on YouTube, if anyone wants to take a look and offer advice... It's called Saving the life of a D43 Oscilloscope and the channel is TeamEnfil.

I didn't clean up the switch or pot contacts, I'm not sure about how best to.

[MotorBikeLes]

I seem to recall there were at least two versions of the Type A amps. On some, the pushbutton moved many contacts, the later one was much simpler (Caution, it is at least 45 years since I looked in one). Those earlier switches are a definite weak point regarding connection integrity. Clean, lubricate, then test. There is a 10 Uf bipolar under the board I think. Usually done for. You can get a 10Uf non-electrolytic these days that is affordable and will fit in the space.
Regarding the C2, was this solid state, or just a bit like the simpler switching of earlier A type. It is a high gain amp from memory, so much more prone to drifting. Try switching on, leaving for 30 mins then set it up as per the manual. Then check. Don't expect stability at switch on.
Les.

[ChrisGadg]

I'll try to clean the switch contacts MotorBikeLes, next step. I hope I don't need to dismantle the switches to do that. Is there a way to clean the pot tracks also? I could also use compressed air to clean it further, rather than just vacuuming it. Switching it on for half an hour before the cleaning I did would have been unthinkable.

[MotorBikeLes]

Most of the rotary pots (controls not presets) can be dismantled and cleaned if you must. Maybe just switch cleaner in the right area would do the trick. In the event you need to replace, I have quite a range of new ones of various values. Singles, doubles etc.
If they are the (cadmium plated) types, there is a small piece of graphite which is a pastmaster at getting lost. Tricky to rebuild, but can be done with care.I have hundreds of the small three leg ones with coloured plastic tops.
Vacuuming around is a waste of time, other than just to tidy up if it is full of dust. I have used compressed air to clean stuff usually, but that won't clean dirty pot tracks.
Les.

[Diabolical Artificer]

I've some two timebase & few vertical plugins for the D43 if they are any good to you. I offered them to someone else recently but have heard nothing. Some of the vert plugins need work. I also have a spare CRT if of any use to you and quite a few ECF80's if you want them, Telequipment scopes use loads of them. Drop me a PM if interested

These scopes also have those horrible Plessey red & yellow caps in, change on sight. The vert plugins also have a lot of 10u 350v de-coupling caps in which may need changing. I got myself about 50 to restore my D43.

Andy.

[ChrisGadg]

Thanks but I don't have time to work on it in this depth. I almost never use it but can't part with it either. Someone else mentioned checking the capacitors also. Thanks for the pointer