Hot rod deluxe with very noisy overdrive channel

[punkykatt]

Hello everyone. Does anyone here have any experience with these amps having excessive noise on the overdrive channel? The amp works great  and is very quiet in the clean channel. There is plenty of overdrive and the switching works fine. Any help is much appreciated.   https://el34world.com/charts/Schematics/files/Fender/Fender_hotrod_deluxe.pdf

[punkykatt]

Finally had some time to get out the listening device. The ugly hiss/hash sound starts at V2 pin 1 plate and continues to the speaker. Something must be funky in the more drive gain circuit. Need some advice to check that. Might be out of my league with the tools I have? Thank you for any input.

[tubeswell]

The way the 5W cement resistors are mounted directly tight to the board in these amps causes multiple problems with other nearby components overheating - which can include the sort of symptoms you’re describing. Check out some of the videos on YouTube about these amps.

[punkykatt]

Thank you for the reply Tubeswell. While checking all the components, I did get a weird reading on R23 100k so I pulled the PCB and lifted one leg and it read spot on so put it back in. Inspected all solder joints and redid a few questionable ones. The two 5w R`s in the power supply your talking about were mounted about 1/8" above the board so the burning of the PCB in that area in minimal.    I know of two other tech`s  a couple of towns over that have better test equipment than I have. I`ll ask the owner to see if they want to look at it.

[pdf64]

Consider replacing R22, V2a anode load resistor.
There’s a mistaken belief amongst folk that bad parts are obliged to measure bad on their meter.
Unfortunately there’s not really a correlation between resistors being noisy and measuring outside their resistance tolerance. ie just because it’s in tolerance doesn’t mean it isn’t the cause of the noise.

[punkykatt]

Was up late last night . I will try that.

[pdf64]

Consider replacing R22, V2b anode load resistor.

Sorry, got mixed up between looking at the schematic and writing the response.

[punkykatt]

pdf64, I took another look at the schematic. R22 in not in play in the clean mode. But why am I getting the noise on R16 in the OD mode?

[punkykatt]

Got her tamed down in the OD More Drive Channel. Replaced V2 A&B plate resistors R16 & R22, V2B cathode  bypass cap C9, C11 Master Volume bypass cap and C23 V1A plate coupling cap. Hiss/hash gone but way too much gain in this circuit as usual, so I dropped R19 value down a bit. Now you can turn the Drive and the Master Volume knobs past 1.5.  Thanks for the reply`s everyone.