I don't have my schematic's for that one in hand. I do know some fender amps used what was called a opto-isolator circuit. The opto-isolator also known as a photo-resistor. Its composed of a neon bulb on one side which flashes faster and brighter with the adjustment of the speed and intensity controls. The other side of it has kind a screen resistor which varies the amount of current flowing through it according to the intensity of the light it is exposed to. I wouldn't count this as fact for the amp your asking about.
Joe
A resistor is an electronic component whose purpose is to "resist" the flow of electrical current. All resistances are measured in ohms (symbol: Ω), which is the units for volts divided by amps. Ohm's law relates these three quantities: Volts = Amps x Ohms or E = I x R
Screen resistors are used to limit screen current.
Joe
Your enthusiasm for learning is great. I'm happy to answer your questions and pass long the knowledge. I just don't want to see someone get hurt by not thinking safety first. When you have a chance read up the working of tubes themselves, you'll see the names of parts like, Plate, Suppressor, Screen, Grid, cathode, etc. I recommend that you read up on tube amp safety. Reason is that if your asking questions like this and your messing around inside a tube amp creates a Dangerous situation. There is (for say) a proper way to work on these types of amps to help eliminate the danger and to keep you from getting electrocuted.
Also a book on tube amps would have a better expalination than I would have.
The tetrode
As the name suggests, the tetrode tube contained four elements: cathode (with the implicit filament, or "heater"), grid, plate, and a new element called the screen. Similar in construction to the grid, the screen was a wire mesh or coil positioned between the grid and plate, connected to a source of positive DC potential (with respect to the cathode, as usual) equal to a fraction of the plate voltage. When connected to ground through an external capacitor, the screen had the effect of electrostatically shielding the grid from the plate. Without the screen, the capacitive linking between the plate and the grid could cause significant signal feedback at high frequencies, resulting in unwanted oscillations.
The screen, being of less surface area and lower positive potential than the plate, didn't attract many of the electrons passing through the grid from the cathode, so the vast majority of electrons in the tube still flow by the screen to be collected by the plate. The greater the screen current, and the greater the changes in its value with signal. it will be seen that plate current is a function of screen voltage. If the screen is intercepting electrons destined for the plate and if, triode-like, its current flow varies with it voltage it can be seen that that the potential on the screen will vary with the voltage drop across the resistor connecting it to the plate.
joe
Questions from me now :D:
Where can you find out how to work on tube amps safely? Other than being taught directly by a tech, as it's impossible to find one round here thats willing to teach. Any good books you can suggest?
Doug
Questions from me now :D:
Where can you find out how to work on tube amps safely? Other than being taught directly by a tech, as it's impossible to find one round here thats willing to teach. Any good books you can suggest?
Doug
http://geofex.com/gtramps.htm
http://www.aikenamps.com/ (Click on "Tech Info.")
http://ax84.com/ Lots of good links here.
http://firebottle.com/ampage/bbs/ Lurk a while on the various guitar amp building and repair boards here.
"A cheerful heart is good medicine."
