Oscilloscopes for Dummies

melchman

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After 10 years at his hobby (addiction) I find myself wanting to know more about the board and repairs.

I am passing the solder and recap stage and looking at the logic probe and oscilloscope stage.

I have two disadvantages here:
1) no Electronics Engineering degree
2) Mac owner

What are the recommended tools for logic and signal analysis? Are oscilloscopes still independent devices or is there an app for that these days?
 
It really depends on what you are looking to repair. If you want to fix old black and white games, all you really need is a logic probe, which can be had for less than $20 new. You want one with an audio indicator. In fact, the logic probe does a LOT better job than a scope in most cases, since you can very quickly walk through a circuit without having to keep looking at the screen.

If you're wanting to fix power supplies, check for ripple, troubleshoot hum in audio amplifiers, etc - the scope will let you see the waveform and is very handy. Also, you can check for clean signal outputs from chips, optos, etc. For MOST basic repairs, any old used 'scope from a hamfest would suffice - expect to pay $30 or less. I have an early 80's Tektronix, complete with huge dent in the side and cracked knobs that I got for free. But it works perfectly, and has served me very well. Tektronix makes some very reliable stuff. For bench testing vector games, you'll want to find one with an X/Y mode.

If you're doing newer things, and/or really want to see what's going on, a faster scope might be necessary - but personally, I almost never need one. I don't even have a good scope, on the rare occasion I've needed one, I can borrow one from a friend of mine.

If you really want to learn digital logic, start with a logic probe and a cheap old scope, and learn how to use them.

-Ian
 
I have a 20 Mhz O-Scope in mint condition I got for free. I have used it to view vector games when I have a dead monitor an not much else as I don't have a clear understanding of troubleshooting with one effectively.

I have a logic probe that I use all of the time and it has a very short learning curve to use.
 
What is a Logic Pulser compared with a Logic Probe?

A logic probe displays the state of a given signal - high, low, or pulsing. A logic pulser creates signals.

You can therefore use the pulser to, say, supply a signal to an input of a chip when the main processor isn't running, and check the output on the probe, to see if the chip is functioning.

I have both, but rarely use the pulser. For the most part, debugging the board running naturally is easier.

-Ian
 
I have a 20 Mhz O-Scope in mint condition I got for free. I have used it to view vector games when I have a dead monitor an not much else as I don't have a clear understanding of troubleshooting with one effectively.

I have a logic probe that I use all of the time and it has a very short learning curve to use.

The scope will allow you to see the signals that are there where a logic probe only will tell you a signal is there. You can readily see if there is a clean signal or a dirty one. It is very helpful for audio signals and excellent if you have a working board to compare to a non working board.

The learning curve is very rapid. You only have to adjust to SEE the signal. The trick is to see what a working signal should look like. Once you get used to it it will speed up the repair process. Like a bicycle or any other thing you have never used before, jump in and get your feet wet/peddling.

I would start looking at audio signals on a working board so you know what things on the scope should look like.
 
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