How to connect O-scope to amp?

[shizzzon 461]

I can't believe i am making this thread but there is something not right and evidently i have forgotten.

I had this problem before but it was like 4yrs ago and i cant remember what i did.

Ok here it goes-

I have a sundown 100.4

I am playing a 600hz tone.

I hooked up a speaker to chan 4 only to make sure it would output power, it does fine, i even played some music on it so i know the amp works fine.

Now, i connect the probe from the oscope to the positive terminal of chan 4 and the ground clamp of the oscope to the negative of chan 4.

When i connect just the positive, i get this crazy wave form. When i connect the ground clamp, ... nothing changes.

If i connect the ground clamp to chassis ground, the wave form gets even more crazy.

If i connect the probe and clamp to same positive wire, reading disappears obviously.

I know the oscope works because i use it for my db meter and the wave form is fine on it.

I have had this problem before and i cant remember what i did to the oscope but i had to wire it up some weird way to get it have a perfect wave form but i cant remember how that was...

I have tried with and without a speaker connected to that terminal and it makes absolutely no difference on the wave form.

[shizzzon 461]

ok, i just connected the o-scope up inside the house to an amp and it read out fine so i must have some noise issues in the car i'm assuming...

[shizzzon 461]

ok i'm an idiot...

I got the sundown 100.4 tuned now.

What happened was the volume needed to be turned WAY up on the head unit before it got a correct reading.

Also, the display setting on the oscope needed some changin.

After foolin with it for about 10 min, i finally got that perfect waveform to appear for me so everything is normal now.

[mrray13 30]

lol, glad to hear you got that worked out!

wheeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee