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Tektronix 465: Weird Trace behavior


Jose Alfredo
 

Hi,

I had just replace my tekscope capacitors, and when testing everything was ok. But, when I closed the cabinet, the trace, in ground position, for both channels, get curved down, in the left end of the trace. If I remove the cabinet, it gets fixed. Can anyone of you help me with this issue?

Thanks

Jose Alfredo


Colin Herbert
 

A few questions:

Are there any internal cables that might be getting caught between the cabinet and something else?

Is the mu-metal shield on the crt OK. Mu-metal can lose its magnetic screening properties if it is bent or otherwise worked; it's a bit like work-hardening and can only be fixed by annealing, which isn't going to be easy with a scope.

Has the cabinet got magnetised some way while it was off? You could try taking the cabinet off and move it around the scope when it is turned on. If it has got magnetised, that might show it up. It shouldn't be too difficult to de-magnetise the case, but you will need a fairly strong de-magnetiser.

Colin.

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Jose Alfredo
Sent: 28 July 2020 18:46
To: TekScopes@groups.io
Subject: [TekScopes] Tektronix 465: Weird Trace behavior

Hi,

I had just replace my tekscope capacitors, and when testing everything
was ok. But, when I closed the cabinet, the trace, in ground position,
for both channels, get curved down, in the left end of the trace. If I
remove the cabinet, it gets fixed. Can anyone of you help me with this
issue?

Thanks

Jose Alfredo