My Orange Rockerverb combo died in practise

[Parker]

So I had band practise last night. Half way through a song the signal just went. It also had that dreaded burnt toast smell! All the valves are still glowing and there is nothing obviously burnt out on the PCB. The valve protection system thingy didnt light up either. I'm sure its going to be a costly repair, but can anyone give me some idea as to what it could be?

Cheers

[ICBM]

Is the HT fuse blown? If so it's probably just a blown power valve - you can't usually tell by looking at them, and they normally light up (the orange filament glow) as well.

[Parker]

I really hoped you'd come to my rescue! The whole amp stays lit up - valves, power light and all - just no sound at all. There is a valve protection system built in that knocks the quad down to a duo (at reduced volume) to get you through a gig - there is a red LED that comes on, I presume if ther HT fuse for that pair has blown?.I havent removed them to check though - I will when I get in.

[ICBM]

I really hoped you'd come to my rescue!

I saw the bat-signal .

I actually find it useful - its kind of "remote research" into what goes wrong on amps I may later come across .

The whole amp stays lit up - valves, power light and all - just no sound at all. There is a valve protection system built in that knocks the quad down to a duo (at reduced volume) to get you through a gig - there is a red LED that comes on, I presume if ther HT fuse for that pair has blown?.I havent removed them to check though - I will when I get in.

Not sure - I haven't been inside one of these newer ones. There may also be an overall HT fuse, possibly inside.

Another possibility is that if the amp has a 'choke' resistor instead of an actual choke, that it's blown - which can happen if a power valve screen shorts badly, and might also explain the burning smell. If so it's a bench job to fix, although not a big one.

Don't worry too much, Oranges are well-built and it's unlikely to be anything really serious.

[Parker]

Ive checked the two fuses which I beleive to be the HT fuses and they are fine. I openned it up again and there are 2x 500mA fuses labeled FS1 and FS2. I replaced those (with 250mA as thats all I had at the time). The FS1 blew when I flipped it from standby. It worked again though. I will go out and get the propper fuses, but there is obviously an underlying issue. Could this be the power amp valve do you think?

[ICBM]

Ive checked the two fuses which I beleive to be the HT fuses and they are fine. I openned it up again and there are 2x 500mA fuses labeled FS1 and FS2. I replaced those (with 250mA as thats all I had at the time). The FS1 blew when I flipped it from standby. It worked again though. I will go out and get the propper fuses, but there is obviously an underlying issue. Could this be the power amp valve do you think?

Very likely, yes. From the values those are HT fuses - I'd guess the valve fail fuses are probably cathode fuses for the two valve pairs.

Replace the blown fuses with the right values and pull the power valves. If it doesn't blow them again, it's a valve issue - almost certainly only one, so put the valves back one at a time (safe with this sort of amp - put the amp onto standby when actually putting the valves in) until the fuse blows again, and you've just put the bad one back in .

If it does blow again with no power valves, it's a tech job unfortunately.

[Parker]

Very likely, yes. From the values those are HT fuses - I'd guess the valve fail fuses are probably cathode fuses for the two valve pairs.

Replace the blown fuses with the right values and pull the power valves. If it doesn't blow them again, it's a valve issue - almost certainly only one, so put the valves back one at a time (safe with this sort of amp - put the amp onto standby when actually putting the valves in) until the fuse blows again, and you've just put the bad one back in .

If it does blow again with no power valves, it's a tech job unfortunately.

OK cool - thanks! Off to the hardware store it is then! Huge thanks for your guidence!