A tip when using a Multimeter to check voltages

[johnboy1313]

This is a quick video I made showing how I probe for voltages with my meter and a lead with an alligator clip on each end.

http://s177.beta.photobucket.com/use...E0039.mp4.html

[tom66]

Re: A tip when using a Multimeter to check voltages

Nice video. I usually place the black probe in the chassis -- a spare wall mount hole usually works -- but this will probably work better.

You should upload it to YouTube for others as photobucket has a limited audience.
See some of my repair videos: http://www.youtube.com/playlist?list...cFK9eYEsDtCVe9

[johnboy1313]

Re: A tip when using a Multimeter to check voltages

I will, I've never uploaded to YouTube. I can never remember my password.

[tom66]

Re: A tip when using a Multimeter to check voltages

You now use the same account as your Google Account so if you have Gmail it automatically logs you in...

[johnboy1313]

Re: A tip when using a Multimeter to check voltages

https://www.youtube.com/watch?v=h4RV1gdF8u0

[budm]

Re: A tip when using a Multimeter to check voltages

Good video.
You may want to add info about circuit ground ref point for the Primary (HOT) side and the Scondary (COLD) side. I see you have the scope probe attached to the primary side but I cannot see how the scope ground wire is attached, the Tv should be fed by the Isolation transformer otherwise when you hook up the scope ground lead to the primary side circuit ground, you will get big spark. Safety Ground is not circuit ground ref.

[tom66]

Re: A tip when using a Multimeter to check voltages

He is probably probing the cathode of one of the output diodes... in which case that's on the secondary.

If you don't mind bad differential error and have a 2-channel scope with an add+invert option it's possible to probe the primary without an isolation transformer, as long as the PSU uses y-caps to earth (or you'll see lotsa noise.)

[mariushm]

Re: A tip when using a Multimeter to check voltages

First thing I'd do is replace that lead, it's almost broken at the jack. It's not safe... but then again that whole meter isn't safe.

[johnboy1313]

Re: A tip when using a Multimeter to check voltages

Yeah, the scope probe is attached to one of the output diodes. Has nothing to do with this video. I was testing the PSU prior to making this video.

[budm]

Re: A tip when using a Multimeter to check voltages

Just want to make sure we give warning for newbie.

[randtek]

Re: A tip when using a Multimeter to check voltages

Good tip johnboy1313. I like to connect my alligator clip to my test lead like this though. This method gives you insurance that if the hanging end of the probe/alligator clip swings and touches anything, you don't get smoke or sparks. I learned this from personal experience.

[tom66]

Re: A tip when using a Multimeter to check voltages

Just want to make sure we give warning for newbie.

I hope that someone who can afford an oscilloscope has a small amount of prior experience to electronics and knows not to probe the primary directly...

Then again, I have been known to be wrong. Some people have too much money. I saved the money from 3 months of repairs to buy the Rigol scope.