Recent content by TerryS

My xtension 10 measures 2mm x 49mm when doubled. Of course it's hard to measure a stretchy rubber belt accurately. I would guess it is about 100mm long. When I put a mark on it and try to lay it along the roller, I get 97.3mm.

Change the trigger mode from normal to auto.

Like Avionic said. Or desoldering braid and lots of flux. Sometimes it even helps to flow some fresh (leaded) solder on the joint. Attack it from both sides if you can. Avoid pulling the lead through while the joint is hot or you risk lifting a pad.

You still need to ground the scope to the generator. You are picking up 60hz noise from the difference between the scope ground and the generator ground. If that 60 hz signal is large enough to clip the input of the scope (depends on the scope vertical sensitivity settings) then the A-B math...

Could be temperature dependent then. As you increased the output level, the transistors heat up. A can of component cooler might speed up locating the issue.

Doesn’t matter. It’s the level of the output signal that matters.

No I was talking about the amp. Oscillations often pop up as the level is increased. That's why they often look like in your scope shots, affecting the peaks of the waveform.

Yep. My bad. I should have peeked at the datasheet. If it was the generator, wouldn't you have seen it on both channels? An oscillation will often pop up as you slowly raise the level. Did it act like that?

Since it is oscillating on the upper half of one channel, that narrows down the area of circuitry you need to look at. If you have a decent oscilloscope probe you can carefully probe around starting at the upper power transistor on that side. You may find a place where just probing it makes...

It’s a 15MHz scope. My bet is there is a much higher frequency oscillation, like several tens of MHz. The scope filters and attenuates it so that it ends up looking like that. Did you substitute the transistor types? Maybe some ‘faster’ transistors?

Looks like an oscillation on one of the channels.

Not sure I understand the question, but you should see the bulb brighten as the amp is first switched on, then dim back down as the inrush fades. This will probably have a slight effect on the inrush current, but should still let the caps charge to their normal full voltage (or very close to...

The characteristic of an incandescent bulb that makes it useful in the dim bulb tester is the positive temperature coefficient of the filament. The resistance of the filament is low when the bulb is off (cold filament) but increases as the filament heats up. So when placed in series with the...

I can’t tell from the picture. Do you also have a ground connection at the power supply?

Change the trigger coupling to HF REJ.