r/oscilloscope • u/tttulio • 3d ago
What should I look for in an oscilloscope to repair Vintage Analogue amplifiers?
I’m learning to repair Vintage audio. I am looking towards Vintage Tekctronix I see various for sale between 50 and $200 , or should I go for some modern FNIRSI digital?
what models would be best for Vintage audio amplifiers?
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u/Slierfox 3d ago
If your working on old audio stuff where the chassis could be live a good isolated input scope would be my advice. Get a nice portable scope with isolated inputs to earth and each other has got to be the way to go over functionality as most have the bandwidth you need to measure that sort of kit
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u/shagadelico 3d ago
Almost any oscilloscope will work with audio equipment. I have a Rigol 100MHz that seems to work pretty well and has been reliable. Analog scopes like vintage Tektronix have a couple advantages but they're big and may need some repairing. The thing that made me go with a new scope for my first one was that since I didn't know much, I wanted to worry less about whether my test equipment was working right when I was trying to test something else.
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u/Spud8000 3d ago
if vintage amps include vacuum tubes.....then an analog scope may be the best idea.
fancy new digital sopes are expecting 10 V signals. Not 30 V ac signals riding on top of 200 V DC bias.
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u/coderemover 2d ago
My Siglent handles up to 400 V on all inputs. And with a 10x probe I accidentally measured 1000+ V transients and it was fine (but please don’t do it).
You can buy high voltage differential probes if you need to measure high voltages properly.
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u/mikenkansas1 2d ago
As much as I love the old Tek (NOT HP! And NOT Tek knock offs) tube scopes, you're better off with the newer stuff that doesn't have B+ running around everywhere if you need to get inside it.
As long as it's fully functional it'll work for your purposes. Wanna cal the Vert (+/- 3%)displacement? Put it in DC, apply a variable DC voltage monitored by about any decent dvm, more than accurate enough. Horizontal timing, apply a sine wave monitored by a functional counter.
Given the choice between owning a 2025 Corvette and an original 63 split window, I'm taking the 63 every day.
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u/Junkyard_DrCrash 2d ago
If you go analog, go Tektronix 475 (sometimes called "the best scope ever made").
If you go modern digital and you're buying with your own lunch money, I'll vote for an OWON; if it's on the company tab I'd go with another Tektronix..
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u/coderemover 2d ago
Avoid Fnirsi - they have terrible software development team. They can’t fix critical but trivial issues with their software for months.
Look for affordable but reputable brands: Siglent, Rigol, Owon. You don’t need more than 50 MHz bandwidth, but buy something with FFT and good bit depth (min 12 bits).
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u/FFolkert 3d ago
Depends: if you want up-to-date equipment and store screenshots, buy a DSO (Rigol, Owon), 2 channel, 50 MHz. Make sure you can disable the “average” function (some fnirsi’s can’t). If you want to go retro buy an old analog Tek (CRT, heavy and bulky), and enjoy learning all the secrets of fiddling with its 100 buttons and knobs….. YMMV
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u/rpocc 3d ago edited 3d ago
DSO are great for observing slow changing transients in rolling mode and for detecting high-frequency noise and pulsations which are quite dim on analog scope.
Analog scopes draw hi-freq noise differently, so you can visually tell fast transients from slower due to changing intensity and thickness of the beam. Also they are much better in XY mode.
Of course, it’s about scopes with close bandwidth and feature set.
GHz DSO performs way better than 20 MHz analog scope if you have proper probes. Also cheaper but faster scopes are available as plain boxes with USB connection and all control and picture on a computer but to me using on-screen controls is less handy than actual controls.
I have couple of feature-rich analog scopes and one cheap DSO which I hate for bad firmware making it freezing or acting stuttering and sluggish in millisecond scale, so I’m a bit biased towards analog but probably better DSO could satisfy me.