Marconi TF1331 Oscilloscope

[pwdrive]

Yes yes, but what does it all mean, is the answer 42.

Good luck.

Lawrence.

[Skywave]

Alan - re your cct. diagram as in post #40. Did you use a PC app. to create that dwg.? If so, what was it called? Your dwg. looks nice 'n' crisp and clean.

Cheers,
Al. / March 15 //

[AlanBeckett]

Sorry Al, it's AutoCAD.
I just keep adding Symbols to my Library and then join them together.
What you see is a scan of a plot - not very efficient

Still no Caps to finish the job. I'm hopeful for tomorrow.

Alan

[Skywave]

Yes, yes, but what does it all mean? Is the answer 42 ?

Good luck.
Lawrence.

Yes, Lawrence, the answer to the problem with this Marconi 'scope, model 1331 is indeed '42'.

Why? Because 1331 = 121 X 11; 1+2+1 = 4; 1+1 = 2, and '4' and '2' → 42.

Marvellous things, numbers.

Al. / March 15, 2013 //

[Skywave]

Thanks Alan.

It's just that for a long time I have been searching for a simple-to-use cct. drawing PC program that:
(a) doesn't cost the earth (read: free, ideally);
(b) doesn't require hours of study and a good knowledge of software 'things' to be able to use it;
© doesn't contain lots of other features that I don't need: such as pcb layouts, etc.
(d) produces clean, crisp schematics with a library of electronic 'things' which includes vintage components, like valves, etc.

I'm sure there is something out there somewhere that meets that spec.: it's just that I haven't found it yet. But I do recall seeing something that meets that description of mine many years ago in my then line of employment. And that ran under DOS on a PC/XT, too.

Al. / March 15. //

[AlanBeckett]

At long last the HV Capacitor(s) arrived. I only needed one 1n really. I must have chosen the slowest Supplier on the net.
Anyway, armed with my Diagram, new Caps, Resistors and Valves I set to putting it back together. After an hour of fiddling I had the PCB Re-installed.
Now for the big switch on, wait for 90 seconds for the Delay Timer to kick in and ........ nothing
Ah, well, sometimes it just works. At that stage I couldn't feel my feet so I've knocked off for a think.
Tomorrow, I hope, I'll do some more measurements.

Alan

[Mark Hennessy]

Thanks Alan.

It's just that for a long time I have been searching for a simple-to-use cct. drawing PC program that:
(a) doesn't cost the earth (read: free, ideally);
(b) doesn't require hours of study and a good knowledge of software 'things' to be able to use it;
© doesn't contain lots of other features that I don't need: such as pcb layouts, etc.
(d) produces clean, crisp schematics with a library of electronic 'things' which includes vintage components, like valves, etc.

I'm sure there is something out there somewhere that meets that spec.: it's just that I haven't found it yet. But I do recall seeing something that meets that description of mine many years ago in my then line of employment. And that ran under DOS on a PC/XT, too.

Al. / March 15. //

Have you tried one of the various Spice packages? LTSpice is completely free, and the schematic drawing is reasonably intuitive as these things go. You can just ignore the simulation aspects if that doesn't appeal. I've also got an old copy of B2Spice (http://www.beigebag.com/) that does reasonable schematics too.

I've had the same problem - hence all the schematics on my website were drawn as bitmaps in Paint Shop Pro (an example attached). It's tedious, as everything is a cut and paste exercise, but it does mean you retain complete control. But all those were done 10 years ago, and I doubt I'd have the patience or time these days.

Actually, it's not too bad once you get going... But I need to have another bout of research, as there must be something out there.

Mark

EDIT: The diagram should be totally "crisp". If it looks a bit soft, your browser and/or the image viewing software on the forum is scaling it. Right-click, choose "Open link in new window" or similar, which should give you just an image, and try clicking on it to expand it. Of course, those with widescreen monitors will probably be OK. Perhaps I should find a smaller one that will look OK on a small screen...

EDIT #2: The headphone amp should look OK.

[Skywave]

Have you tried one of the various Spice packages? LTSpice is completely free, and the schematic drawing is reasonably intuitive as these things go.
I've had the same problem - hence all the schematics on my website were drawn as bitmaps in Paint Shop Pro (an example attached).

Mark

Thanks for that, Mark. No, I haven't tried LTSpice, but have heard of it and have seen drawings that it has produced. I'll put it in my 'things to do' list: I think there's just about enough room left to squeeze it in!
Yes, in the past I have tried the 'ultimate drawing D-I-Y approach' using Corel Photo Paint. And yes, with enough time and patience, you can indeed produce 'things' that are just what you want - but it's a lot of hard work (least, I found it so).
Your examples, seen here, are indeed crisp, clean and well-proportioned.

Al. / March 21 //

[Skywave]

Now for the big switch on, wait for 90 seconds for the Delay Timer to kick in and ........ nothing
Ah, well, sometimes it just works. At that stage I couldn't feel my feet so I've knocked off for a think.
Tomorrow, I hope, I'll do some more measurements.

Alan

Keep at it Alan - you know you'll win in the end. You have appropriate kit for measurements, the cct. diag., and, most importantly, the experience, and patience to see this project through to a successful conclusion. But as here, this on-going cold weather is certainly limiting my favourite activities.

At that stage I couldn't feel my feet so I've knocked off for a think.

Hmm: in my case, I think I'd be tempted to knock off for a drink - something like a whisky mac!

Keep us posted: thanks.

Al. / March 21, 2013 //

[AlanBeckett]

The temperature has returned to something approaching compatibility with life so it was time to have another go.

First I measured the DC Voltages. That didn't tell me much, ie nothing was desperately out of kilter, so I had to adopt the alternative approach of measuring everything.

At least after I'd unsoldered the PCB I could go back to the house to thaw my feet out.

I constructed a BoM and checked all the components - see attached.

Not to put too fine a point on it I suspect that the easy thing to do is to change all the Resistors, provided I have all the values.

The Capacitors, apart from the Hunts that I've already changed, should be OK, which is not surprising as they're all Ceramics. I had a minor panic with C518 which was miles out when measured in circuit, but OK when I took it out.

While I was at it I corrected a few typos that had crept into the Schematic

So, onward and upward.

Alan