Repairing and Restoring Tube Radios - part 2

This is for the electronics geeks out there. I am repairing and restoring an old Marconi model 220 tube radio and I thought I would make kind of a do-it-yourself documentary to share my little hobby with everyone. In part 2, we build a little tester with some basic shop materials to test the transformer and chassis for shorts.

Category:

Howto & Style

Tags:

• radio
• tube
• electronics
• capacitor
• repair
• marconi

[piper4seeformerly]

Is a rectifier the same thing as a diode?

[aliendaddy32]

A diode is an electrical component that only allows electricity to flow in one direction, therefore a diode is the most basic component of a rectifier. Usually a full wave rectifier will have an arrangement of diodes AND capacitors to convert alternating (bi-directional) current to direct (uni-directional) current.

[radlam64]

Poor mans's variac - light bulbs.

[aliendaddy32]

I'm not poor, just cheap!

[bandet888]

The bulb will always glow dim briefly do to inrush current

[bandet888]

You can leave the rectifier in to see if the radio has ANY problems whether it's the transformer or after. If it does than you can go from there to figure it out. If the radio is safe you can test and leave all the components pluged in. Just another way of testing. But yes either a light bulb set up or a variac with a ammeter is a must.

[ciprianwiner]

thanks for the ideea with the light bulb :)

[hydrolisk1792]

That is a nice tester with the light bulb.

[FrubberDucky]

Great video, very helpful.

[TAC19jm]

great radio!

thank you.

[bandet888]

Another way of testing is to leave the rectifier tube in and plug into the bulb to see if the radio has ANY kind of shorts (whether the power transformer or after the power supply), if there is then determine if it's in the power supply or something else.

[bandet888]

@watcher818 you are correct, a lot of paper caps will check good but what happens is that they start breaking down and get leaky under high voltage.

[NJPurling]

The current limiter with a tungsten filamant light bulb is a easy test item to make.

In mine I have a on/off on the output, so no need to go near the radio. There is also another switch that bypasses the lamp so the radio thus gets the full mains voltage if the lamp shows no fault condition.