Supersonic problem : Help needed

[KevKahuna]

I recently picked up a year old Supersonic 22, in immaculate condition, still boxed, played and sounded great. I was looking forward to it's first outing to band rehearsal tonighty but when I plugged it in, absolutely nothing came out of it ! The red power light is on, the power valves are glowing, the valves seem seated, the speaker lead is plugged in...what more can it be ?. Apart from the four mile journey laid flat in the back of the car it's not been out the house. I was gutted...had to plug into an old Roland keyboard amp which was awful. Can anyone shed any light on where the problem might lie ? Thanks.

[citizen68]

Check the HT fuse first - if any of your power valves failed this fuse might have blown, possibly taking out a resistor or two in the process - look for any signs of overheating/ scorching on your output valves.. If you find evidence of this then take it to a tech for repair.

ICBM or ECC83 will help you much more than above (which I only know because my amp had the exact same symptoms a wee while back)

[KevKahuna]

Check the HT fuse first - if any of your power valves failed this fuse might have blown, possibly taking out a resistor or two in the process - look for any signs of overheating/ scorching on your output valves.. If you find evidence of this then take it to a tech for repair.

ICBM or ECC83 will help you much more than above (which I only know because my amp had the exact same symptoms a wee while back)

The Fuse (under the black screw cap) appears fine. The power light comes on, and there is a faint hum from what i presume is the transformer. No signs of any overheating. I've only played it for half a couple of hours since I got it and it was absolutely fine. Very frustrating, I worry about taking it to a gig now without back up and the main reason for getting it was to reduce what I carry around. i wil check the fuse again but I assumed that if blown i would have no power...unless there is another one somewhere that I've not seen. Thanks for your help.

[dindude]

Sorry to hear this Kev, I never had any issues when it was with me. Have you checked the speaker cable at the speaker end to see if this hasn't worked loose / is making good contact? Do you have any spare power valves to try? I'm happy to pop a couple of 6V6 in the post to you if not (I have a few lying around) so that you can at least rule this in or out.

Hopefully one of the techy types can help a bit more - you always have the 5 year transferrable warranty to fall back on if it can't be solved.

[citizen68]

Puzzled me too as the power light & valves were all on but I had no sound when my amp had the problem.

Nice to hear about the warranty - when my amp went I needed 4 new 6L6's + tech's time which came to £90

Best of luck getting a resolution..

[Viz]

10 quid it's the guitar lead

[ICBM]

Do you hear any hum from the speaker? (You may have to put your ear up against it.) If so, the speaker is working.

It won't be the fuse on the back panel (or the internal filament fuse) if the valves light up. Nor the HT fuse, because the amp doesn't have one - I'm pretty sure, none is shown on the schematic. You can check the HT supply by looking very closely into the power valves when switching from standby to on - you should see a blue glow within the plate structure, and sometimes blue on the inside of the glass, but these can sometimes be a bit tricky to see. If you see blue, the HT supply and the power valves are working.

If so, check the preamp valves by replacing with a known good one, one at a time.

[KevKahuna]

Sorry to hear this Kev, I never had any issues when it was with me. Have you checked the speaker cable at the speaker end to see if this hasn't worked loose / is making good contact? Do you have any spare power valves to try? I'm happy to pop a couple of 6V6 in the post to you if not (I have a few lying around) so that you can at least rule this in or out.

Hopefully one of the techy types can help a bit more - you always have the 5 year transferrable warranty to fall back on if it can't be solved.

Don't worry Daniel, it's nothing you did, it was working fine at home. Unfortunately it appears the transferable warranty is only if in the US !! Blooming typical eh? Thanks for your offer, I may take you up on it

I'm gonna have a look again this evening, but it is puzzling me. I'd hoped it was the guitar lead, but I tried the bassists and it was no different. I also used my lead all evening through another amp, so it's not that. I keep looking for something obvious . Before I delve in I think it's time to crack open a Guinness !

[KevKahuna]

10 quid it's the guitar lead

Bet you 20 it's not

[KevKahuna]

Do you hear any hum from the speaker? (You may have to put your ear up against it.) If so, the speaker is working.

It won't be the fuse on the back panel (or the internal filament fuse) if the valves light up. Nor the HT fuse, because the amp doesn't have one - I'm pretty sure, none is shown on the schematic. You can check the HT supply by looking very closely into the power valves when switching from standby to on - you should see a blue glow within the plate structure, and sometimes blue on the inside of the glass, but these can sometimes be a bit tricky to see. If you see blue, the HT supply and the power valves are working.

If so, check the preamp valves by replacing with a known good one, one at a time.

No speaker noise at all, just a faint hum from the transformer. Momentary blue glow in both valves when switching from standby to on.