Re: New Member intro and needing help


druid_noibn
 

Hi David,
Indeed, there are a few circuits that don't do well with ramping currents - thanks for the comments.

Kind regards,John aka DBN


On Saturday, July 2, 2022 at 11:17:21 AM EDT, David C. Partridge <david.partridge@...> wrote:

> Bring it up slowly on a Variac. This has the advantage of giving alum electrolytic capacitors time to reform before they get full voltage

Just don't do this if the 'scope has a switching Power Supply (like most 7000 series and later 'scopes).

Just plug in an turn on (after checking the voltage selector is set correctly).

Dim bulb approach is fine.
D.

-----Original Message-----
From: TekScopes@groups.io <TekScopes@groups.io> On Behalf Of Jim Adney
Sent: 02 July 2022 12:48
To: TekScopes@groups.io
Subject: Re: [TekScopes] New Member intro and needing help

On Fri, JulĀ  1, 2022 at 09:50 AM, druid_noibn wrote:

What would be a good or appropriate power-up procedure for for older 'scopes that sat on the shelf for a few years?
There are two good approaches:

Bring it up slowly on a Variac. This has the advantage of giving alum electrolytic capacitors time to reform before they get full voltage

or

Build a fixture that puts an incandescent bulb in series with the old device. I built mine using a 2x4 box and a cover that had an outlet and a socket for a screw-in (Edison base) lamp. Choose a bulb that will almost, but not quite, blow the fuse. As long as the lamp doesn't glow brightly, you're okay. If the lamp suddenly goes bright, you know that something in your old device has shorted.

You could also do both, using the Variac to bring the voltage up slowly, while watching the lamp to monitor the current.

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