Hoagtech wrote: ↑Thu Oct 31, 2024 9:51 pm
Can you give me a pointer on how to adjust time base and 10V DIV?
There are three knobs you most need to pay attention to.
1- "Vertical"
The voltage knob just changes the range you are displaying. You want to dial it to somewhere around the voltage range you are looking for. I would expect a 6VAC RMS signal to be something like between 10-30V peak-to-peak, which just means the highest it goes and the lowest it goes in the waveform. I guess you could start lower, like 5V per division and if the wave is off the screen, increase the voltage. Volts per division refers to the individual squares on the scope screen; each box is a division, so changes the volts/div changes the scale.
Another important setting here is the AC/DC coupling setting. On your scope, it's found by pressing the probe number button for each probe. In this case you would press the "1" button to get to that menu. The coupling setting would be the first setting (on the left). Press the button to scroll through the options and/or use the scroll wheel to the upper-righthand side of the screen.
Set it to AC coupling to essential "center' the waveform
Vertically around the Zero Volts line on the screen. This is useful because it allows you avoid any DC Offset. DC offset is when you have an AC waveform that is held at voltage level higher than or lower than zero volts.
Take for example a square wave that is 5V peak to peak, but it has a 200V DC offset. In order to see that waveform, you would have to set the volts/div at something sensible, like say 2V/div. However, if you did that, your waveform would be way, way up above your screen because it's floating up at the 200VDC line at its center. So you use AC coupling and it removes the DC offset and just shows you the AC "component" of the waveform.
If you want to see a "DC component," then you put it in DC coupling and you crank up the volt/div to a place where you can see the line
2- Horizontal
The time base knob adjusts the frequency range of the scope in the same way that the volt/div effects the voltage, but it's stretching the representation of time/div instead of voltage. If you turn it counterclockwise, you decrease the time (make it slower) and if you turn it clockwise you increase the time (make it faster).
In this case, "faster" means a shorter length of time is represented by each division. It goes from seconds up to nanoseconds. The vast majority of what I usually do is in the milisecond to microseconds range, or bascially in the middle. 50 microseconds seems to be a good place to start for me usually.
I would put it there and then wind it to the left if nothing is there to see if you are just missing a slower signal.
3-Trigger
This sets the voltage level at which the scope will capture data each time it refreshes. I would leave it on auto, and then you can use the level knob to bring it to just above or just below zero. It will show a yellow line to indicate the trigger level while you are moving the knob. You might have to tweak it to stabilize the image when you find a signal.
Your multimeter is RMS, so it should be able to peek the voltage, providing it's not a really weird waveform. I'm not sure how even such a DMM would behave if faced with something very irregular, but if you've seen people do it in videos, then I would believe it's possible.
If that's the case, then there's probably something wacky going on, but you'll still need to look at what's coming out of the heater pin on the BK to know what the deal is.
Finally Do I probe PIN 1 Heater Voltage with the probe and clamps to the side of the metal case?
I would attach the ground clip to a place on the circuit of the BK467 that is labelled ground on the schematic. You can also measure a ground point against the metal case of the 467, and if you have continuity, then it's the same as attaching directly to ground inside anyway.
