1974 Deluxe Reverb Noise Question

[Burpy]

I've had this '74 Deluxe for about 10 years and it has worked flawlessly during that time. Recently, there's this static-y type noise (the best way I can describe it is like a record needle on a scratched up record before it gets to the first track). I took it apart and noticed that there's a cracked resistor (470K) across the pins of one of the output tubes. I put it back together and sure enough, if I pull the tube with the cracked resistor, the noise stops. It's going to be a while before I can get a new resistor sent up here (I live in Nunavut) and I'd like to play it with the noise if it's not going to kill my amp.

So: what does this resistor do? Why'd it crack? Is it a sign of more serious things wrong? Can I play it like this?

Also: this amp had a solid state rectifier when I bought it off some stupid kid for $200. I put it back to tube rectifier and changed the electrolytics when I got it home.

Thanks!

[RussB]

You may need new power tubes as well. There's a good chance the screen shorted, and took out the (470 ohm, NOT 470k!) resistor.

I use 1 or 2 watt metal film resistors for the screens

[Burpy]

Right, 470 ohms, not Kohms. Sorry. Can you tell me what this resistor does? Why would the screen short?

[SatelliteAmps]

Pretty spot on explanation.

[Blue Strat]

Not sure if someone else said this or not, but those resistors are subjected to serious heat due to their location and should be changed every time you have a cap job done (15 to 20 years max). It's good to locate the new resistors off to the side of the socket.

Heat may have been the only problem but a shorted power tube certainly could be the cause.