Electronics > Beginners
Old analog oscilloscope questions
tedsorvino:
Hello. Another first timer in the forum. I'm also new to the world of oscilloscopes even if I 've studied a bit the concept behind them. But there are many many things to learn. So I decided to buy a cheap ADVANCE INSTRUMENTS - GOULD OS 240 10MHZ Dual Channel Analog Oscilloscope. Mainly for Audio work.
Unfortunately I can't find the exact model manual, but I 've found some quite similar models' ones.
So there are some questions I 've got.
Firstly I would like to know if I have to ground (is it necessary) the device since its mains plug has no mains ground. It's an old two prong plug and there's also a "banana plug" ground socket above it (how can I use that??). I don't know if it's dangerous.
Also, in the front panel there is no test- probe calibration input. How can I calibrate the probes?
There is a strange binding post called Gate o/p. It must be an output. There is something like 15v dc voltage on it. An old Tektronix manual (different brand but seems like it also had the same style of output) writes that it supplies a positive pulse for the duration of the timebase. What does it mean and how could it be useful? Could it be a test point for the probes?
There is also another ground socket next to it. I think this is not useful since there is a ground clip on the probes. Am I right? Should I always use the ground clip for anything I measure (like a multimeter ground)?
Under the devices there are two hole for the two channel balance. Are they test points, or just potentiometers? What do they set?
How can I understand that the oscilloscopes functions and measures correctly.
Here are some photos of the front panel and the particular parts on question
https://ibb.co/nHkmVe
https://ibb.co/czcpiz
https://ibb.co/bZ9DAe
https://ibb.co/ds59iz
These seem really important questions to start with (even if more seem to arise).
Thank you in advance for your time.
Jwillis:
Similar to the 240
http://bee.mif.pg.gda.pl/ciasteczkowypotwor/Gould%20Advance/OS250.pdf
circuit diagram
https://elektrotanya.com/advance_os240_oscilloscope_sch.pdf/download.html
further information here
https://www.radiomuseum.org/r/advance_in_os_240_os240.html
Calibrate probes at the probe it self.
tedsorvino:
Thanks JWILLIS.
I' ve already had found all the relevant information that can be found on the net. At least the obvious one.
Unfortunately the OS 250 manual hasn't got the features I'm asking for. The radio museum site gives no free information and the schematics is not helpful if you 're not a service - repair technician.
How can I calibrate properly at the probe itself?
tggzzz:
--- Quote from: tedsorvino on August 08, 2018, 05:37:24 am ---Firstly I would like to know if I have to ground (is it necessary) the device since its mains plug has no mains ground. It's an old two prong plug and there's also a "banana plug" ground socket above it (how can I use that??). I don't know if it's dangerous.
--- End quote ---
I don't know that specific scope, but unless it is a very unusual scope the protective mains earth must be connected. If it is not connected and a scope probe's shield is connected to a dangerous voltage (e.g. mains), then then entire scope's case will be at that dangerous voltage.
It is also possible, depending on why the scope was "floated", that there is internal damage to the mains transformer.
Have a look at the safety references and scope probe references in https://entertaininghacks.wordpress.com/library-2/scope-probe-reference-material/
The remainder of your questions are not specific to this scope, so any introduction to how to use a scope should help.
tedsorvino:
Thanks TGGZZZ.
But the scope is constructed "floated" and it only has a socket for mains ground. How and where can I connect the ground from there.
On the other hand the calibration issue is not generic. I mean most of the scopes have a test input. This one hasn't. And what this binding post is all about.
Believe me I've read quite a lot of material since last week and nothing answers these particular questions (yet...) ;).
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