Quote:
Originally Posted by ramifer
I have a Telequipment D1011 oscilloscope that lacks the trace corresponding to channel 1 (CH1) and I would like to repair it. I have little knowledge of the oscilloscopes...
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Hi,
The oscilloscope is a system of attenuators and wide band amplifiers for the vertical deflection and a synchronizable or triggered time-base for the horizontal deflection.
To be able to see the results of the activity of these sub-circuits the CRT itself has to be set up and working properly and all of the electrical potentials around the CRT's gun and deflection plates and final anode correct.
However, there are very high voltages and high resistance circuits around the CRT and these exceed the capability of many common multi-meters to test them.
With a two channel scope, if one channel is working, you can sometimes use it as a tool to fault find the other channel fault, if you don't have another scope for diagnostic purposes. A 100:1 and other high voltage probes can be helpful.
Also, in twin trace oscilloscopes there are channel switching circuits that are moderately involved to chop or alternate the beam to each trace, although some early types had twin beam CRT's.
You may not need to delve into the high voltage circuits, but at this point that is not definitely known.
If you have little knowledge of oscilloscopes, this is the risky area, for you safety wise, due to the high voltages, if you plan to attempt to work on it yourself.
So given what you have said, it could be safer to have it looked at by an experienced engineer instead.
If you want to go down the fix it yourself road, the best advice I could give is read up on oscilloscope circuitry and systems and CRT support circuitry and high voltage power supply measurements etc, then study the design of your particular scope for a while first (you will need the service manual and schematics), before diving into it unprepared, which will likely bring you trouble.
When it comes to flow diagrams for fault finding, most experienced engineers know they are usually not worth the paper they are written on and often do not help to resolve the problem, unless say it was a very simple issue to begin with.