Tek 2230 'scope

At 10:24 AM 7/21/00 -0500, John Foust wrote: This is a nice find. The 2230 is an ok scope, it does have some issues but for vintage work they won't be a problem. The easiest way to get it "checked out" is to take it to a calibration laboratory and get it calibrated. This is something you should do on your scopes, especially if you use them for adjusting other things (like drive head alignment). It will cost between $75 and $150 usually for a calibration but when you get the sticker on your scope it will both raise the value (known good), and assure you that you've got a working scope. Plug a probe into channel 1 and then clip the hook to the little bar in the front of the scope that set "cal" or "test" or whatever. It should be metal. Tek puts a calibration signal (60hz on older scopes). Then set the trigger option to "internal" and make sure the single sweep button is "out" or disengaged. You should see a sine wave on the screen. Adjust the amplitude using the channel amplitude adjust and the number of waveforms on the screen with the time base knob (marked in time increments) Scopes are very simple think of them as a piece of graph paper with automatic writing :-), they work like this: - There is a screen that has lines on it like graph paper. Each square is one "unit" - The screen is written to with a beam, the beam is deflected upward and downward by voltage, and deflected left to right by time. - Each channel writes one line on the graph paper. - The value of the units on the graph are controlled by two knobs: One controls voltage sensitivity for a channel, when it reads 1V it means that one unit of deflection of the beam means the probe is measuring 1 volt. One controls the time it takes the beam to go across the screen (called the timebase) when it reads 10nS it means that the beam travels from the left edge of one unit to the left edge of the next in exactly 10nS. - There is a circuit called the trigger circuit that tells the oscilloscope when to start the beam. When it is set to "line" it usually starts 60 times per second (or 50 times in Tony's UK case). - You can also set the trigger to fire based on the voltage seen by one of the channel probes. The two values you set are : Threshold - The voltage at which the beam will trigger. When the probe sees this voltage it will trigger the beam to cross the screen. Rising/Falling - When set to rising the trigger occurs when the voltage starts out below the threshhold and crosses it going up. When set to falling it triggers when the voltage goes past the threshold falling down. In computer circuits this is often the "rising edge" or the "falling edge" of some clock pulse. - Single Sweep is used if the trigger is not supposed to reset automatically and it very useful in glitch detection and for storage scopes. To use a scope as a DMM: Set the trigger to 'line' and the time base to 10mS. You should see a bright line across the screen. Set the probes sensitivity 1/5 of the voltage you expect to measure (for a 5v measurement set it to 1V). Now when you touch the probe to a wire the line on the screen will move up (or down for negative voltages) some number of units. Count them off, including the fraction. Multiply by the voltage setting and that is the voltage you are seeing. To measure 'ripple' on the line, set the probe to "AC" coupling. This puts a capacitor in series with the probe so that any DC value is eventually zeroed out as the capacitor charges. Now crank down the sensitivity to 10mV or less. See the bumpy line? That is signal "ripple" on your power supply. If it is more than a few percent of your regulated voltage then thats a problem. To use a scope as a frequency counter: Place the probe on the signal to be measured (DC coupling), set the trigger to be channel 1 (or 2 if you are using a probe on channel 2) then adjust the threshold until you either get a waveform display your you get a band of green. If you get the band crank the knob on the timebase until you can see at least one complete waveform on your screen. Now use the horizontal postion knob to slide some recognizable point (perhaps the lowest point) of the waveform to set right on top of one of the graticule lines. Now count units (including the fractional unit at the end) until you get to the same point on the waveform. Multiply by the number on the timebase knob to get the 'period' of the waveform. Take 1 and divide it by that number to get frequency. They are really very versatile and useful instruments. If it is fully functional it is an excellent deal. --Chuck