Hopeful to find help with a vintage Japanese tube amp

[52 Bill]

I would try pulling the output tubes and firing up the amp (on a light bulb limiter, if you have one). See if the 1K resistor still bakes with the tubes removed.

It blew the fuse.

Your hand drawn schematic is what I could sort of figure out from your photos. If the fuse blows now that the 1K resistor is replaced, then something on the second side of the resistor is drawing too much current. Even though the second filter cap doesn't test bad with your ohmmeter, it may fail under high voltage. So for now assume that it is okay, but keep your mind open to the fact that it may still prove to be bad.

Having a light bulb limiter will allow you to power the amp up and measure the voltages and see where the voltage dies, which will lead you to the problem with the amp.

[fastmerc]

It blew the fuse.

Your hand drawn schematic is what I could sort of figure out from your photos. If the fuse blows now that the 1K resistor is replaced, then something on the second side of the resistor is drawing too much current. Even though the second filter cap doesn't test bad with your ohmmeter, it may fail under high voltage. So for now assume that it is okay, but keep your mind open to the fact that it may still prove to be bad.

Having a light bulb limiter will allow you to power the amp up and measure the voltages and see where the voltage dies, which will lead you to the problem with the amp.

Ok...I will build one up and start there. Thanks for all the help on both amps so far!

[fastmerc]

Ok...built the bulb limiter. I put in a 1 amp fuse as thats all I have around right now. Without the powertubes in, I turned it on and the bulb got bright for a millisecond but slowly went dim, which from what I understand is what is supposed to happen. Then I put the output tubes back in and it initially went bright, then dimmed all the way down, but then slowly got bright again, I assume as the tubes warmed up. The bulb says its a 53 watt on it even though the package said 75 watt.

[52 Bill]

Then I put the output tubes back in and it initially went bright, then dimmed all the way down, but then slowly got bright again, I assume as the tubes warmed up. The bulb says its a 53 watt on it even though the package said 75 watt.

All of your descriptions sound fairly normal, the question is when the bulb gets bright, how bright does it get? Full brightness of the bulb, half?

Pull just one output tube and try it, any difference? Now swap the two output tubes. What happens?

[fastmerc]

All of your descriptions sound fairly normal, the question is when the bulb gets bright, how bright does it get? Full brightness of the bulb, half?

Pull just one output tube and try it, any difference? Now swap the two output tubes. What happens?

Meant to put it in the last comment but forgot....tried each tube solo in both sockets with the same result for both. As far as brightness I guess I will have to plug the bulb into a lamp and then try again, but I think it was pretty darn bright.