Re: [Amateur-repairs] SETTING UP A TEST BENCH

Excellent advice.

Gary

On 12/24/2023 8:03 AM, Tim Reimers KA4LFP wrote:

"A good rheostat for slowly powering up something that make have been turn off for the last 20, 30, 40 years."

Couple of points here

A Variac (what you're talking about when you say rheostat)

Does NOT LIMIT CURRENT.

A dead short in a DUT will still destroy components like the DUTs power transformer, even sometimes at the low voltage a variac provides. 

Also, a Variac does not protect you from the AC line. A large (massive) number of old shortwave radios and other audio gear had "hot chassis" designs, with no power transformer, and the chassis was physically isolated from the case.

A so-called AC-AC design. 

Best design for a power system for your bench:

Separate GFCI circuit feeding a large isolation transformer, in series with a Dim Bulb Tester in series with the Variac.

The Dim Bulb Tester does limit current to protect you from those dead shorted dried out capacitors that will let all the unobtanium smoke out of your power transformer.

73, Tim KA4LFP 

Morse Code: The original digital mode.