Test Equipment: Oscillocopes

[Brian516]

Wellllll,
I am looking at the schematic for the CH2 vertical preamp and my assessment is that the X100 attenuator is blown.   I don't know how I did it, but I must have.  I am attaching a picture of the internal settings for the CH2 V/div knob, and you will notice that above 500mV/div and above use the X100 attenuator. nothing below that does.  This makes perfect sense, now just to find the part.      I'm almost 100% certain that this is it, so if anyone would be able to confirm this for me, I'll just order the part instead of even opening up the scope and looking around in it.

[Brian516]

I am just going to post this for future reference for anyone who may end up having the same problem.

I correctly diagnosed the problem I was having with channel 2 above 200mV/div - It was in fact the X100 attenuator, and replacing that part did fix the problem.
I am thinking that this may have been the faulty part that was spoken of when I acquired the scope, and it had just enough life left in it to get me thus far on a good cleaning before blowing. (since after doing some researching on no-no's with Scopes, I have found none that I may have done).   

Also, since I still had "noise" from my vertical position knobs after my previous cleaning attempts (especially channel 2), I decided I would take care of that while I had it opened up.
- I loosened the 4 screws on the back of the pot case just enough to be able to shoot some LPS inside of it.  I gave it a shot, worked the pot back and forth a few times, then gave it another rinsing shot, and tightened the screws back up.   This solved that problem entirely.  Now when I adjust the vertical position, even if I turn the knob quickly, I don't get a bunch of scratchy lines across my CRT.   ::thumbs up::

That is all...

[Pirate88179]

I am just going to post this for future reference for anyone who may end up having the same problem.

I correctly diagnosed the problem I was having with channel 2 above 200mV/div - It was in fact the X100 attenuator, and replacing that part did fix the problem.
I am thinking that this may have been the faulty part that was spoken of when I acquired the scope, and it had just enough life left in it to get me thus far on a good cleaning before blowing. (since after doing some researching on no-no's with Scopes, I have found none that I may have done).   

Also, since I still had "noise" from my vertical position knobs after my previous cleaning attempts (especially channel 2), I decided I would take care of that while I had it opened up.
- I loosened the 4 screws on the back of the pot case just enough to be able to shoot some LPS inside of it.  I gave it a shot, worked the pot back and forth a few times, then gave it another rinsing shot, and tightened the screws back up.   This solved that problem entirely.  Now when I adjust the vertical position, even if I turn the knob quickly, I don't get a bunch of scratchy lines across my CRT.   ::thumbs up::

That is all...

Good work.

Don't feel bad about having probs with a used scope.  TK just received a brand new 4 channel digital scope and has problems with channel 4 right out of the box.  Of course, his is still under warranty but, what a pain in the ass.

Bill

[TinselKoala]

Yep, had to send it back to the vendor, and they've sent me a replacement, due to arrive tomorrow.

Here's the video I made documenting the main problem with the channel 4 :

http://www.youtube.com/watch?v=7RvcByoEE5o

[Brian516]

Good work.

Don't feel bad about having probs with a used scope.  TK just received a brand new 4 channel digital scope and has problems with channel 4 right out of the box.  Of course, his is still under warranty but, what a pain in the ass.

Bill

Yes, that is very unfortunate.  Very few, if any companies make anything with the same care and at the same quality level as they used to.  Also, the more functions that are added to something, the more "components" there are to be broken.  (I quoted that since it technically speaking has less actual components due to ICs)  Also, it becomes that much harder to repair since so many things are packed onto a single semiconductor device.
      This is why I have been tossing around the idea of buying a used, time-tested digitizing or digital phosphor oscilloscope.... but then again, if I were to buy new and had an issue, I could just send it in under warranty, and buy an extended-extended warranty.

Considering the point I am at in my electronic education, I think it's better if I don't have a scope that does all the math for me.... A freq counter, pencil & paper, and my brain need their workout!!

TK - Let's all hope that they send a delivery driver that can pick the correct house this time - or that they reamed the idjjot and he doesn't make the same mistake twice.  I'm sure you'll be doing what I'd do, and continually check the tracking status!  haha     Let's PRAY that this scope doesn't have ANY issues at all this time! Or ever, for that matter!