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VARIAC & CURRENT LIMITER TEST-SET

 

 

bulb

The TEST SET is a Lab/ Bench tool that allows consistent and safe testing of Tube Amplifiers or any recently repaired equipment.

 

The TEST SET has the following features:

  1. 0-250 VAC Variac to set the Line Voltage presented to the amplifier
  2. AC Volmeter [0-150 VAC]
  3. AC Ammeter [0-5 Amperes]
  4. Current Limiting via 100Watt Light Bulb
  5. Switch to bypass the Current Limiting
  6. Switch to Connect/Disconnect the Variac adjusted Line Voltage to the Load
  7. Power and Active Neon Indicators
  8. Switch to bypass the Ammeter
  9. Switch to turn the power on/off on the unit
  10. Input and Output fuses

 

IN OPERATION: When the Variac Adjusted Voltage is first transferred to the Load, the light bulb should flash for a second due to the initial power supply surge as the capacitors charge. If the light bulb remains lit, this is an indication that the amplifier connected to the Amp AC Outlet is drawing too much current due to a shorted transformer or electrolytic capacitor... the short in the amp will allow the lightbulb to get the current that it needs to light while limiting the current and saving the amplifier components from damage.

If you were to transfer the voltage to the load without the lightbulb, you would be depending on the amplifier's fuse to blow before the amplifier is harmed. The amplifier's fuse is effective in protecting the amplifier, but, then you have to install a new fuse before you can test again... The lightbulb becomes a resettable fuse...

The common name for this type of tester is a DIM BULB TESTER.

 

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The Duplex AC Outlet is separated into two parts... The top outlet is for the lightbulb and the bottom outlet is for the D.U.T. [Device-Under-Test]

 

duplex

 

 

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The top outlet is transitioned to the lightbulb through the use of a Lightbulb-to-outlet adapter socket...

 

lamp

 

 

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SCHEMATIC

schem

 

 

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REAR VIEW

rear

 

 

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LASER ENGRAVED PANEL

The front panel was designed in CorelDraw© and laser-engraved by AD Engraving in Toronto on a 0.040" thick black-anodized aluminum panel.

panel

 

 

Here is a picture of the old diamond-plate panel with Sharpie© marker labels before the laser engraved panel was installed...

old

 

 

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A smaller Version of a switch-box with the current-limiting only is shown below...

smaller

smaller

smaller

 

Here is the schematic for the smaller unit...

 

ilimit