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Old 20th May 2021, 9:26 am   #1
Join Date: Mar 2016
Location: London, UK.
Posts: 491
Default Rebooting Racal 383-2 Oscilloscope


A forum member has been extremely kind and let me take a classic 17” Racal 383-2 oscilloscope off his hands. The unit dates from 1972, and he informs me that it was last switched on 10 years ago.

It’s a rare unit, with orange phosphor display. With this in mind, I’m determined to take as much care as possible in getting the unit ‘rebooted’. At this point, I have not connected it to the mains, and have no intention of doing so until I’m convinced I’ve done every bit of necessary research. Of course, with units of this age, you can never be 100% sure something won’t play up when being returned to service, but I’d like to take every step that I can.

The most obvious first step should be to remove the external covers and look for any visual clues around electrolytic caps, i.e. leaking electrolyte or suspicious bulging. I will also look for any obvious humdingers such as RIFA caps (doubt it’ll have them).

What other checks would you do?

I have a large variac (about 7A output from memory), so I can ramp it up slowly – but if it contains switching regulation, I doubt that will help? I ought to add that my field is audio, and the HV / CRT area of electronics is well outside of my expertise.

Going ahead of myself and assuming all is ok: the max. BW of the Racal is 10KHz. I have other scopes and analysers with outputs. I was wondering if I'll be able to look at signals above this frequency, if I feed it from these... What about a Thurlby DSA524 ?

Any suggestions gladly received. TIA!
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