EICO Model 460 Oscilloscope at 120VAC

[nexon]

Got my old EICO Model 460 oscilloscope running, mostly just bad filter capacitors.  Here are some pictures of the 'scope in action:

EICO 460

I'd like to be able to run the 'scope at 120VAC, but the B+ current bothers me.  Specifically the wattage on R77.

According to the Instruction Manual, Maintenance Section: 

g) Check for a dc voltage of 45 volts +/-10% across 500 Ohm resistor R77

That would be 4W (E^2/R) @45V, and a maximum of 5W @49.5V. OK, I guess:  it's a 5W resistor...

When I measure the voltage drop across R77 at 115VAC input, I get 50V, at the high end of the acceptable values.  Raising the input to 120VAC, the R77 voltage drop goes to 53V, giving 5.6W.

At the moment I'm running the 'scope at 110VAC, which gives a 48V drop and 4.6W on R77.  Should I just replace R77 with a 10W, and not worry about it?

[SoundTech-LG]

Great old piece. Got one a while ago, probably needs a good recap as well.

I would replace with a 10W, but also install a carefully selected line fuse of appropriate rating to protect that transformer at the same time. That way, if something starts to draw more current, the fuse might go before damaging something else...