HT-5RH Great sound - then nothing

[pb202]

Bought a HT-5RH from a friend, no issues, worked fine.
Plugged in today, OK for 5 minutes then nothing, absolutely nothing.
Valves look powered up (normal looking glow) but no output from either speaker or headphone sockets.
It was cranked up a bit but nothing exceptional.
Not necessarily the power valve as no output on standby.
Could this be the pre-amp valve or one of the fuses blown?

Frustrated!

[thephantum]

Looking at the valves will tell you nothing about whether they work or not. The fact that they glow simply means that the heaters have power. Having said that: 98% of the time, no sound equals a bad tube.

If the emulated out is not working, then there is no signal coming from the preamp. Assuming a known good guitar and a known good cable, the first step would be to test all fuses with an ohmmeter (don't just look at them....again, that will tell you nothing). If you find one blown, be wary of just replacing it. Contrary to popular belief, fuses don't just blow for no reason. So if one of them is open, it blew because something is wrong and amp needs to go to a tech for diagnosis.

If all the fuses test good, try replacing the preamp valve. It could be as simple as that...

[pb202]

Fuse F5 had blown (F2 on HT-5 schematic) caused by one of the bridge diodes failing. Replaced all 4 as a set and the fuse and all now OK