Marconi TF1331 Oscilloscope

[pwdrive]

A dark stormy wet 'n windy night, maybe not the best night for neighborhood watch? sounds disguised by the weather?

Lawrence.

[Refugee]

Thieves don't usually think of that.
They don't like getting wet or getting there booty wet either.

[pwdrive]

That figures, they want an easy life I suppose.

Lawrence.

[AlanBeckett]

Lift-off!
Well, Ignition. I don't think I've cleared the Tower yet, but things are looking up.
Fired it up and checked the voltages again - all fine. However, no spot, although the Beam Locate button worked OK.
So, stuck some AC on the X Input, switched the Timebase to External, twiddled the knobs and got a trace.
So, what's the Timebase doing? Swung the Range Switch round a few times and got a Trace in a few positions - see attached.
So, it's a start. The Timebase waveform on the Tube looks horrible, some of the Controls don't seem to do what I expect and it only runs on some of the positions.
Onwards and upwards.

Alan

   

[pwdrive]

Keep at it Al, does the tube trace look as though it's got a few years in it?

Lawrence.

[AlanBeckett]

Lawrence,

The Tube Brighness is fine. In fact can't turn it right off. No doubt some of the Tube voltages are a bit out yet.
So, yes, it looks as though it will last a bit yet.

Alan

[Refugee]

It sounds like it is time to give all the switches a good clean.

[AlanBeckett]

They've nearly all had a good spray and twiddle. I say 'nearly' because there's a couple that are 'buried'.
I'll get at them soon.

Alan

[pwdrive]

Alan, if the CRT is sharpish then it gives inspiration, proper job.

Lawrence.

[AlanBeckett]

Not much progress today due to other commitments.

So, fire up and check if everything is the same. Gloom and despondency - more ticking and green fuzz on the Tube. However the Timebase is running. Despite it being nearly dark I can't see any discharge even with the lights off - very odd. A careful 'screwdriver test' says there's plenty of PDA available. Switched off to connect my home-made EHT Probe, switched back on and no ticking with a trace as before - even more odd. However, very little PDA. Putting the other AVO Lead back on the chassis fixed that, and yes, I did remember to switch off and make sure it was discharged before I picked it up. The PDA is at about 6.5 kv as before and the trace is nice and bright. I supect I'll have to look when it's really dark. By the way, the 90 Second wait every time I switch on can get very wearing.

Next I put it on a Timebase Range where I get a good Trace and had a look at the signals. The first Picture is the Signal coming from the TB and the second is one of the X Plates - sorry about the quality. It X Amp looks pretty good to me. However, I'll have to RTFM because the Controls aren't 'normal' - aka like what they are these days - and they don't do quite what I expect. The Manual contains a Calibration sequence so I guess that should be next, then I can work backwards.

I'll be glad when this phase is over 'cause working on the underside of the Top Deck can be a bit exciting. I've only managed to get the back of my hand on the 400v once so far but that will last me for a bit.

Alan