Quote:
Originally Posted by cakerack
Hi Denis
OK so I have followed your instructions and I get some results - I get the start of the ugly sine wave you describe but only for about half a cm at the left of the display. If I change the timebase, the waveform fills more of the screen the faster the timebase is set to. It seems to be connected in part to the fact that the waveform gets dimmer towards the right hand side of the screen possibly?
I have attached another video to demonstrate this - have a look at ******************************6YkwyGbQvk6Nv79A6 and you will see what I mean.
During this test the orange trigger light stays on permanently.
I hadn't realised the transistors were pluggable! I have re-seated all of the transistors and there is no change in the symptoms.
I also checked the +24v, -24v and +105v power supply voltages last night and they are all correct.
Cheers
Sean |
I agree with WME_bill on the source of the trace dimming issue. However, try to handle one issue at a time. To me, it looks like the scope does not trigger on the
LINE source either. If my observation is correct, then the issue should be located after the
A TRIG SOURCE switch in the
A TRIGGER AMPLIFIER on
PC 132. So, the first thing I would do is, to check all transistors and diodes on the right hand side of the circuit diagram of PC 132. If you have no second scope, maybe you can use setting the trigger source to
LINE to some extend. In this configuration, you should be able to measure a 50 Hz frequency at the base of TR3, if the
A TRIG SOURCE switch
S1 routes the signal correctly. Then you could try to trace that signal.
However it is kind of hard to get in there while the plugin is installed and running. To get better access, you can remove the aluminum bar at the side by removing the scope handle via the nut at the inside of the case. A more sophisticated option would be to make an extension cable, like in my posts
here and
here using a Cinch 81 731 AA 16 edge connector (search for "Cinch 81/731/16/EG" on google to find some).