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Old 29th Mar 2020, 5:58 pm   #1
sparkymike
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Default Solartron CD 1400 OSCILLOSCOPE problem

On my Solartron CD 1400 scope, when I tried the probe test socket,I do not get the square wave.The trace moves up around 1 cm but that is all.
So far I have checked back to R5 (56K) and continuity and resistor are ok. Could the fault be in valve V3 ? ECF82
Mike.
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Old 29th Mar 2020, 8:39 pm   #2
WME_bill
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Default Re: Solartron CD 1400 OSCILLOSCOPE problem

CD1400 probe test.
You will have to tell us a bit more.
I assume you are referring to the probe test output on the CX1443 timebase module, which is the TB gating waveform, of about 50v pk to pk.
This is produced from the timebase gating valve as part of the normal free run condition, as it also turns the sweep on and off.
If the scope otherwise produces a trace and synchronises an input waveform, then the only possibility is the series resistor R5 and the wire to the outlet socket.
If the scope does not produce a sweep, then you have got to start looking at the timebase operation, and then indeed, V3 ECF82 could be giving trouble.
But first check the Stability control operation, as that should produce a free running sweep at fully clockwise, and also the probe test output.
wme_bill
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Old 29th Mar 2020, 9:02 pm   #3
sparkymike
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Default Re: Solartron CD 1400 OSCILLOSCOPE problem

Hi Bill,
the scope is fine apart from the above problem. The series resistor R5 I have checked and it is fine. I wondered if it was something I was doing as I also tried the test probe socket on my Advance scope OS2100 with same result. (or no result !!) I probably have a spare valve in the garage, but it is pretty cold out there at the moment, so will wait until the morning.
Mike.
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Old 30th Mar 2020, 10:46 am   #4
WME_bill
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Default Re: Solartron CD 1400 OSCILLOSCOPE problem

CD1400 _ CX1443 problem.
Have you looked at the waveform produced at the triode anode of V3. This is the timebase gating waveform, switching the scan on and off. Can you confirm that you get a proper display in both triggered and free run (with stability control fully clockwise.)
I still suspect the operation of that gating valve V3 circuit. A monostable, tied one way by the trigger from V2, and then tipped over by the end of the sweep through MR3. As you have a second scope, use that to check the operation of this part of the circuit. Well described in the manual.
If the TB pulse is correct at pin 1 of the ECF82 triode, you only have a resistor R5 and bit of wire to check.
wme_bill
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Old 1st Apr 2020, 10:03 am   #5
sparkymike
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Default Re: Solartron CD 1400 OSCILLOSCOPE problem

Hi Bill,
I have had to shelve this project for a while and this scope has other problems which I will sort when time allows. Luckily I have another dual trace scope as stand by . Thanks for all advice so far, will fall back on that later I am sure.
I must remember to look for that ECF 82. The valve next to is is also an ECF 82, perhaps I could substitute it for test purposes, or maybe that could create more problems !!
Mike.
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