Tektronix 475A Help!

[XMA]

Hello, guys so I today bought a Tektronix 475A for $40 but it got problems that make me regret buying. so here a list of problems, and please help me out with fixing it.
1 - Back fan supper load for no reason.
2 - aligning the horizontal axis is really broken like if I try to align, it will jump across and will make a really small change. and with that, it will jump back and forward if u don't find a good spot and that good spot is still very good.
3 - I can't seem to get a clear view, I do focus but it doesn't help much, and as u can see in the picture the square wave is really not clear, u can only really see the top and bottom.
4 - whenever I change the time per division knob, the signal starts to double and I cant get a single clear signal, i need to find a perfect division spot for it to not double.

[james_s]

It sounds like the main problem is that you need to learn to properly use the the instrument before assuming that it's defective. You're trying to measure a signal with a high bandwidth scope using a clip lead rather than a proper 10x scope probe, what you're seeing is pretty much what I'd expect. Try enabling the BW Limit and it should get a lot less fuzzy, although you'll still get some fuzz without using a good probe. The probe and probing technique is very important, more so the higher the bandwidth of the scope.

For the issue you get when adjusting the time scale it sounds like you aren't setting up the triggering properly.

For the horizontal jumping around you might have a dirty pot, but do realize that the control has both course and fine adjustment on a single knob, if you turn it past a point it will make a much larger change.

[Old Printer]

Also, you do not have the grounding clip attached to the scope ground. You can use the outer ring on the external trigger BNC connector.

It looks like a pretty clean unit, and you are getting a trace, so for $40 bucks it looks ok so far.

Get on YouTube and have a look at Alan's videos. He is pretty much a TEK scope guru. Watch every scope vid you can find, I promise it will be worth your time.

https://www.youtube.com/channel/UCiqd3GLTluk2s_IBt7p_LjA