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This issue has arisen with my analog scope. A lil love tap used to fix it but now it seems to persist. The worst part is that it affects the triggering. I dont even know how to explain it so here are some pictures. Nothing looks too amiss inside. Any ideas on what the problem is?
Registered Member #2123
Joined: Sat May 16 2009, 03:10AM
Location: Bend, Oregon
Posts: 312
Since tapping it made it go away, that makes it a contact issue.
I like to gently tug on wire harnesses, gently rapping selector switches, and wiggling or re-seating edge connectors, to see if such problems can be made to disappear.
It depends on your comfort level on how invasive you want to be during trouble-shooting.
Registered Member #2463
Joined: Wed Nov 11 2009, 03:49AM
Location:
Posts: 1546
I looks like the beam switching logic is not blanking, or intermittantly blanking the beam as it shifts up and down.
You have 2 channels but only 1 pair of vertical plates and 1 vertical power amplifier, so a level swither is moving the beam between the places on the screen you set with the position pots.
The deflection amps in scopes like that one uses transistors and resistors that get hot and may crystalize the solder. Look for discolored resistors and cold solder joints.
In the 'no signal picture' the 'fade out' in the middle of the trace shows power filtering may be bad. With the sweep set low enought to produce that many square waves of the 1 kHz. probe calibation signal, a bad filter could get right down to crt blanking levels as well as cause much assorted mischief.
Whacking scopes like that isn't a good idea, it can dislodge structures inside the crt causing shorts, and a delicate reverse-whack is needed to un-short them.
the anomaly IS in sync with the mains... I didn't see any puffy caps or anything that looked burnt. Is it okay to scope the scope's own 12v and 5v power supply rails?
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analog scope problem
