Gould OS 255 Oscilloscope - how to use? - UK Vintage Radio Repair and Restoration Discussion Forum

Uncle Bulgaria · 16th Jun 2019, 6:58 pm

Ahoy,

I'm not sure it counts as 'vintage' but looking at what some people around here use it's certainly not a current model!

I was given this by an old physics teacher and have always heard how handy they are. However, I have no idea what I'm doing with it, and am aware of stories of connecting them up wrongly to the item under test and causing big problems.

I have downloaded a few books from various online repositories, but none seem to go into the real basics.

Can anyone give me a rundown of how I could use this to troubleshoot audio circuits, and any tests I can do to see whether it needs any repair or calibration itself?

Herald1360 · 16th Jun 2019, 11:04 pm

Well, a very basic point is to remember that the probe ground clip is earthed, so DON'T connect it to anywhere on a live chassis set.

Unless you're using a x10 probe, it's also a good idea not to probe any HT, anode or other high voltage areas either.

Otherwise you can probe away. DC coupled it can give a quick rough idea of any dc present at the probed point, to see low level ac signals in anode or grid circuits, use ac coupling. Twiddle the Y gain, timebase and trigger controls to get a stable trace within the screen boundaries.

If you're probing round low level RF connections, a 10-100k resistor in series with the probe tip will help to avoid upsetting the circuit being looked at without reducing signals too much, at any rate up to medium wave frequencies.

Don't expect to see waveforms exactly like textbook pictures, especially for modulated RF signals. The gross frequency difference between audio and RF will mean that a locked trace will only show the envelope or the RF clearly, not both at the same time.

Have fun!

Andrewausfa · 17th Jun 2019, 10:30 am

I found Alan Wolkes videos really useful when I was learning to use a scope and, actually, to refer back to.

There's a good number of basics videos explaining timebases, probes etc etc in Alans playlist and he explains things very simply.

https://www.youtube.com/playlist?lis...6BF38BC2E068E0

Andrew

Ed_Dinning · 17th Jun 2019, 7:17 pm

Hi, google for "the X,Y,z" of oscilloscopes by Tektronix.
It should tell you all you need to know.

Ed

16th Jun 2019, 6:58 pm	#1
Uncle Bulgaria Nonode Join Date: May 2016 Location: Cornwall, UK. Posts: 2,333	Gould OS 255 Oscilloscope - how to use? Ahoy, I'm not sure it counts as 'vintage' but looking at what some people around here use it's certainly not a current model! I was given this by an old physics teacher and have always heard how handy they are. However, I have no idea what I'm doing with it, and am aware of stories of connecting them up wrongly to the item under test and causing big problems. I have downloaded a few books from various online repositories, but none seem to go into the real basics. Can anyone give me a rundown of how I could use this to troubleshoot audio circuits, and any tests I can do to see whether it needs any repair or calibration itself?

16th Jun 2019, 11:04 pm	#2
Herald1360 Dekatron Join Date: Feb 2007 Location: Leominster, Herefordshire, UK. Posts: 16,535	Re: Gould OS 255 Oscilloscope - how to use? Well, a very basic point is to remember that the probe ground clip is earthed, so DON'T connect it to anywhere on a live chassis set. Unless you're using a x10 probe, it's also a good idea not to probe any HT, anode or other high voltage areas either. Otherwise you can probe away. DC coupled it can give a quick rough idea of any dc present at the probed point, to see low level ac signals in anode or grid circuits, use ac coupling. Twiddle the Y gain, timebase and trigger controls to get a stable trace within the screen boundaries. If you're probing round low level RF connections, a 10-100k resistor in series with the probe tip will help to avoid upsetting the circuit being looked at without reducing signals too much, at any rate up to medium wave frequencies. Don't expect to see waveforms exactly like textbook pictures, especially for modulated RF signals. The gross frequency difference between audio and RF will mean that a locked trace will only show the envelope or the RF clearly, not both at the same time. Have fun! __________________ ....__________ ....\|____\|\|__\|__\_____ .=.\| _---\__\|__\|_---_\|. .........O..Chris....O

17th Jun 2019, 10:30 am	#3
Andrewausfa Octode Join Date: Dec 2010 Location: St Ives, Cambridgeshire, UK. Posts: 1,180	Re: Gould OS 255 Oscilloscope - how to use? I found Alan Wolkes videos really useful when I was learning to use a scope and, actually, to refer back to. There's a good number of basics videos explaining timebases, probes etc etc in Alans playlist and he explains things very simply. https://www.youtube.com/playlist?lis...6BF38BC2E068E0 Andrew __________________ Invisible airwaves crackle with life. Or they should do. BVWS Member

17th Jun 2019, 7:17 pm	#4
Ed_Dinning Dekatron Join Date: Jan 2004 Location: Newcastle upon Tyne, Tyne & Wear, UK. Posts: 8,194	Re: Gould OS 255 Oscilloscope - how to use? Hi, google for "the X,Y,z" of oscilloscopes by Tektronix. It should tell you all you need to know. Ed