Tube Amp Restoration

[capwizard]

I try to do Tube Amp Restoration, Anyone wants share the experience? How can I start?


HH Scott 222C Tube Amp Restoration Part 1
https://www.youtube.com/watch?v=3o6MD_zTtUM

HH Scott 222C and 222D Tube Amp Restorations - Part 2 - BG025
https://www.youtube.com/watch?v=khugZQYOGoQ

#242: How to use an oscilloscope. Plus, seeing signals in antique radios | NJARC
https://www.youtube.com/watch?v=niBGkqlh2XY

[keeney123]

Re: Tube Amp Restoration

First does the unit work? Pins 2 and Pins 6 on the tubes should be the heater pins. These pins need to have continuity. If you read an open than the tube cathode is burnt out.

[capwizard]

Re: Tube Amp Restoration

Who invented amplifiers?
Although he liked to refer to himself as the "father of radio," American physicist and electronics engineer Lee de Forest might be better described as the "father of the amplifier." In the early years of the 20th century, he was working in radio ("wireless telegraphy" as it was then often called) and had filed a couple of dozen patents on improved antennas and receivers. On October 25, 1906, he filed a patent for a "device for amplifying feeble electrical currents": a compact, electron vacuum tube called the Audion, later known as the triode (because, in its final version, it had three key electrical components inside). Although de Forest originally imagined the triode as a telephone-circuit amplifier, it eventually became an essential component of radio receivers. Despite inventing the Audion, de Forest neither perfected it nor ever really understood how it worked (the two things may well have been connected); it was left to others (notably Irving Langmuir of General Electric and Edward Armstrong, inventor of FM radio) to turn the idea into a practical device and explain the physics behind it.

How, then, does it work? The sealed glass vacuum tube (shaded gray and labeled D, from which all the air has been pumped out) has three key components inside, which I've colored red, blue, and green. On the left, there's a wire filament (red, F) heated by a battery. This is the cathode or negative terminal. On the right, there's a platinum plate (green, b), which is the positive terminal. In between them, there's a grid of platinum wire (blue, a). When the filament is heated, negatively charged electrons boil off it and are pulled toward the positively charged plate, making an electric current flow. A negative voltage is also applied to the grid, effectively "braking" the flow of electrons. Because the grid is so close to the filament, even tiny changes to its voltage will make a huge difference to the current that flows from the filament to the plate. If we consider the grid to be the amplifier's input, the cathode-plate circuit is its output; a small signal applied to the grid can become a much larger, amplified signal at the plate.

Vacuum tubes based on the triode made splendid amplifiers, but they were large, unreliable, and power-hungry. When John Bardeen, Walter Brattain, and William Shockley developed their "solid-state" transistor in 1947, they solved all three problems at a stroke, making possible small, portable, highly reliable amplifiers for such things as hearing aids and transistor radios. When integrated circuits were invented, in the late 1950s, they led to smaller, more complex amplifier circuits packaged as single chips (as op-amps typically are now).

[jiroy]

Re: Tube Amp Restoration

Lack of available parts will be a big handicap , so i thing it's a waste of time Capwizard dude . One tube at least seem totally out of any range visually .
Even Transistors and digging a long distance past won't fit today as Integrated circuits are the champ today ..But maybe you're planning to be an antics collector , lol ...

[keeney123]

Re: Tube Amp Restoration

Who invented amplifiers?
Although he liked to refer to himself as the "father of radio," American physicist and electronics engineer Lee de Forest might be better described as the "father of the amplifier." In the early years of the 20th century, he was working in radio ("wireless telegraphy" as it was then often called) and had filed a couple of dozen patents on improved antennas and receivers. On October 25, 1906, he filed a patent for a "device for amplifying feeble electrical currents": a compact, electron vacuum tube called the Audion, later known as the triode (because, in its final version, it had three key electrical components inside). Although de Forest originally imagined the triode as a telephone-circuit amplifier, it eventually became an essential component of radio receivers. Despite inventing the Audion, de Forest neither perfected it nor ever really understood how it worked (the two things may well have been connected); it was left to others (notably Irving Langmuir of General Electric and Edward Armstrong, inventor of FM radio) to turn the idea into a practical device and explain the physics behind it.

How, then, does it work? The sealed glass vacuum tube (shaded gray and labeled D, from which all the air has been pumped out) has three key components inside, which I've colored red, blue, and green. On the left, there's a wire filament (red, F) heated by a battery. This is the cathode or negative terminal. On the right, there's a platinum plate (green, b), which is the positive terminal. In between them, there's a grid of platinum wire (blue, a). When the filament is heated, negatively charged electrons boil off it and are pulled toward the positively charged plate, making an electric current flow. A negative voltage is also applied to the grid, effectively "braking" the flow of electrons. Because the grid is so close to the filament, even tiny changes to its voltage will make a huge difference to the current that flows from the filament to the plate. If we consider the grid to be the amplifier's input, the cathode-plate circuit is its output; a small signal applied to the grid can become a much larger, amplified signal at the plate.

Vacuum tubes based on the triode made splendid amplifiers, but they were large, unreliable, and power-hungry. When John Bardeen, Walter Brattain, and William Shockley developed their "solid-state" transistor in 1947, they solved all three problems at a stroke, making possible small, portable, highly reliable amplifiers for such things as hearing aids and transistor radios. When integrated circuits were invented, in the late 1950s, they led to smaller, more complex amplifier circuits packaged as single chips (as op-amps typically are now).

Actually the grid plate gets and alternating voltage frequency signal which is then amplified in the output.

[vinceroger69]

Re: Tube Amp Restoration

i have been watching this mans videos on tube repair tv/radios for a while
https://www.youtube.com/watch?v=NrglRHeihvg