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Hi all,

I have a very unstable 7A15A Plugin ... for example, signal varies in amplitude on some Volts/Div settings, but not others, incorrect Readout (incorrect numbers, missing symbols), signal changes when touching the Volts/Div knob.

As the Plugin is quite dirty inside, I am in the process of removing the Readout/Attenuator pcb's and Cam switch as a Unit to clean the switches properly. I have removed everything except the BNC. I am unable to get a decent grip of the BNC nut without damaging other components ... C100 and the Attenuator shield mount are blocking sockets or tube spanners. What do you recommend as the best approach???

This is my first attempt at pulling apart one of these Plugins. Advice appreciated.

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Cheers,
Ian,
Melbourne, Australia

I do not have first-hand experience with the 7A15A but the input to the attenuator is similar to other products that require trucks or special tools to reach the BNC nut.

You might get lucky with needle-nose pliers to hold the nut and twist the BNC. It will only rotate a couple of degrees but if repeated you can loosen the nut. If you try to turn the nut with pliers you will likely slip and gouge and damage something.

A much safer approach requires modifying a wrench; cutting and grinding. See photograph at

/g/TekScopes/album?id=287576

Correction: TRICKS not trucks!

Hi Clark,

Thank you for the advice and photos ... I have finally succeeded in getting the BNC nut undone ...

For anyone with same issue ... disconnected all the Front Panel switches, removed the Readout pcb, then removed the Front Panel with Cam roller switch intact. I then had sufficient space to use a 'modified' a 9/16inch open ended spanner similar to Clark's. All the Finger contacts are now easily accessible ... ie. Readout and two sets of Attenuator switches.

Maybe now I can troubleshoot the real issues ... :)

Thanks,

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Cheers,
Ian,
Melbourne, Australia

Good on ya!