EEVblog Electronics Community Forum
Products => Test Equipment => Topic started by: elex_enthusiast on August 21, 2015, 05:21:07 pm
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Hi there,
Just want to share the joy of having my first oscilloscope. It's been quite long since I became a member here but this is the first time I started my own thread. I am an electronics hobbyist/repairer of consumer electronics for more than a year since I graduated. I am not a full time repairman (as I only do repairs to earn extra income, and I work as a social worker) and don't have much experience on repairing electronics. So to speak, I was learning things the hard way with only a few multimeters to depend on. Being poor and "equipment starved", I was having a hard time saving a few penny to buy an oscilloscope (without any idea where to outsource for a good one, and ebay is not an option since I am incapable of paying stuff online), I made a friend unexpectedly with a guy here a.k.a Terrahertz and offered his oscilloscope for free as he wants to get rid of stuff laying around his workshop. I didn't expect it, and never asked for it. But heh I couldn't resist his offer as much as I badly need it (it's a 20MHz BK precision 2120, and good enough for a giveaway scope). It's dead but he managed to fix it and send it to me with some other stuff. Here's how its story begun:
http://everist.org/NobLog/20150731_simple_scope_funny_fault.htm (http://everist.org/NobLog/20150731_simple_scope_funny_fault.htm)
After a few days of waiting with excitement, it finally arrived from Oz.
(http://s26.postimg.org/e7xf183k9/DSCN3216.jpg) (http://postimage.org/)
Everything was doing fine until I noticed that the channel one (above ) overshoots and the channel two (below) undershoots a bit. And it made me think that maybe the internal adjustments was changed due to handling while on its way to Philippines, but he actually didn't noticed it before sending :-BROKE
(http://s26.postimg.org/oypn0n6kp/IMGP0031.jpg) (http://postimage.org/)
I was worried and confused how to make it right myself without any available gears to use for calibration. Fortunately he also provided the instruction and service manual for it. So I scanned it hoping that I might find relevant information on how to correct the thing, then I figured out that the input attenuation needs to be adjusted using a function gen (to generate a 1KHz 20v p-p squarewave) but I have none. So i decided to do it and try my luck as I was only depending on the scope's calibrator for a reference (the out ouput frequency is close to 1KHZ only at 200mv). Luckily I was able to correct it by adjusting the trimpot VR307 and VR308 for both channels. :phew:
(http://s26.postimg.org/44hvwk1l5/IMGP0048.jpg) (http://postimage.org/)
(http://s26.postimg.org/fsbxr3qq1/IMGP0047.jpg) (http://postimage.org/)
(http://s26.postimg.org/oxfp784qx/IMGP0035.jpg) (http://postimage.org/)
(http://s26.postimg.org/f0dv5nbwp/IMGP0054.jpg) (http://postimage.org/)
So far everything's fine now and I enjoy playing with it. Love to see actual waveforms than just numbers :-DMM. And I would like to thanks "Terrahertz" for that. :-+
So what was the story of your "first oscilloscope"? Please let us know.
Best regards,
elex-enthusiast
Ahhh!! bad english..
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Sweet, you got a new tool, and the satisfaction of fixing it!
And good on Terrahertz!
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Sweet, you got a new tool, and the satisfaction of fixing it!
And a child thrown in for no extra cost. What a deal! :)
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Good deal enjoy! :popcorn:
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And a child thrown in for no extra cost. What a deal! :)
Oh! That was my son. Just got lucky to know someone with good heart to donate his scope instead of dumping it like anyone else did for such an old scope. ;D. Old but still useful for someone like me who can hardly (and hopeless) afford to buy fancy ones.
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Don't worry about the age of that scope. When you have exhausted it's capabilities you will know a tremendous amount about electronics. With patience an a small amount of auxiliary equipment (Like the sound card in a computer), you can do quite sophisticated things like transfer functions and impulse responses.
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Everything was doing fine until I noticed that the channel one (above ) overshoots and the channel two (below) undershoots a bit. And it made me think that maybe the internal adjustments was changed due to handling while on its way to Philippines, but he actually didn't noticed it before sending :-BROKE
To me it looks like slightly off compensation on probes themselves and not oscilloscope settings, but could be wrong on this one :)
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Everything was doing fine until I noticed that the channel one (above ) overshoots and the channel two (below) undershoots a bit. And it made me think that maybe the internal adjustments was changed due to handling while on its way to Philippines, but he actually didn't noticed it before sending :-BROKE
To me it looks like slightly off compensation on probes themselves and not oscilloscope settings, but could be wrong on this one :)
I agree. Check the probe compensation.
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I agree. Check the probe compensation.
I already adjusted the probes' compensation but it has nothing to do with the overshooting of each channels :-//. Still a lot to learn with the scope.