ShortScale.org

It powers on, all tubes glow, but no sound.

I get the usual hum/pop when I plug the cable into the guitar.

If I turn the amp volume up really high (on either channel) I do hear some faint/muffled/distorted guitar sound.

Any ideas? I never play with the volume higher than 2 or 3, and the amp hasn't been transported anywhere for over a year.

When I’ve had similar issues with Fender amps it usually turns out to be the reverb tank or cables to said reverb tank

Not sure if that’s the culprit here though

Nick wrote:When I’ve had similar issues with Fender amps it usually turns out to be the reverb tank or cables to said reverb tank

Not sure if that’s the culprit here though

If that was the case, wouldn't the Normal channel be OK though?

That said, I'm not getting the usual springy sound when the amp is rocked/tilted. The cables to/from the tank seem OK though...

I'm guessing you have tried other guitars and leads first.

Try pulling all the tubes and cleaning all contacts as well as you can with some electrical contact cleaner before refitting them. Check the jack socket hasn't bent a little bit and is giving a good connection. I'd try retubing before taking to a tech, then if the new tubes don't work at least the tech has a new set to fit for when the amp is repaired.

GreenKnee wrote:I'm guessing you have tried other guitars and leads first.

Try pulling all the tubes and cleaning all contacts as well as you can with some electrical contact cleaner before refitting them. Check the jack socket hasn't bent a little bit and is giving a good connection. I'd try retubing before taking to a tech, then if the new tubes don't work at least the tech has a new set to fit for when the amp is repaired.

It's definitely the amp, not the guitar or cables. All the tubes are properly seated and glowing. I don't really want to replace them if there's nothing wrong. The issue is present when plugged into any of the four jack sockets, so it's not that.

Anyone recommend any London amp repairers? Preferably east side.

GreenKnee wrote: Try pulling all the tubes and cleaning all contacts as well as you can with some electrical contact cleaner before refitting them. Check the jack socket hasn't bent a little bit and is giving a good connection. I'd try retubing before taking to a tech, then if the new tubes don't work at least the tech has a new set to fit for when the amp is repaired.

100% do this, and having a spare set of tubes is a must, regardless; this way, you can troubleshoot what's going on without getting a tech involved now, and in the worst case, just have spares for when a tube invariably shits the bed.

Tubes can still have "gone bad" while still maintaining their glow, so I wouldn't consider that a metric of them being fully functional.

Doog wrote:

GreenKnee wrote: Try pulling all the tubes and cleaning all contacts as well as you can with some electrical contact cleaner before refitting them. Check the jack socket hasn't bent a little bit and is giving a good connection. I'd try retubing before taking to a tech, then if the new tubes don't work at least the tech has a new set to fit for when the amp is repaired.

100% do this, and having a spare set of tubes is a must, regardless; this way, you can troubleshoot what's going on without getting a tech involved now, and in the worst case, just have spares for when a tube invariably shits the bed.

Tubes can still have "gone bad" while still maintaining their glow, so I wouldn't consider that a metric of "they're all fine"

Ah OK, thank you. I know next to nothing when it comes to amps. I don't gig, so have no need for emergency parts on standby. I'd assumed glowing meant good. Should I replace just the smaller preamp ones or the power ones too?

If you're non-amp savvy, I'd really suggest watching a few videos on Youtube about servicing tube amps; potentially lethal voltages in there, Knowing Is Half The Battle, etc.

[youtube][/youtube]
Lovely background music, top level stuff though. Changing the tubes on most amps is fairly straightforward (not requiring taking off any scary back panels etc.), but I've no experience with your model, so let's both watch the above video! - (looks to be easy and safe enough here)

Your amp has a lot of tubes, (6 preamp tubes of 2 types, a rectifier tube, 2 power tubes) so it makes everything a bit more tricky to diagnose:
http://www.amplifiedparts.com/sets-by- ... rb-reissue
http://www.ampvalves.co.uk/product-cat ... xe-reverb/

When you crank the volume to hear said faint guitar signal, do you also get the usual background noise you get from turning your amp up? If so, I'd wager that it's one/more of your preamp tubes.

Your amp has four 12AX7s and two 12AT7 in the preamp. Those models are interchangeable, just that the 12AT7s are lower gain and placed in a specific spots in the circuit for THOSE FENDER VIBES.

If you want to do this on the cheap, you could buy a single 12AX7 (or 12AT7), sub it into each position to see if you can locate a shitty one in your current set. This would be the first thing I'd do tbh.

Noisy Cat wrote:If I turn the amp volume up really high (on either channel) I do hear some faint/muffled/distorted guitar sound.

The first valve that's common to both channels is the phase inverter, V6. You could try pulling out the reverb tank driver V3 or the vibrato oscillator valve V5 and swapping that into the V6 position. Caveat; I'm assuming the RI uses the same valve numbering as the original.

NickS spitting science as per usual; I'm guessing a 12AX7 will still work okay in all of those positions though, right? Even though they're nothing to do with "preamp gain" or anything?

I edited my post back a bit as to not be chatting too much misinfomed shit

Thanks very much Doog and NickS; I'll have a play around with swapping the tubes this weekend – fingers crossed

Noisy Cat wrote:Thanks very much Doog and NickS; I'll have a play around with swapping the tubes this weekend – fingers crossed

Also, just so you're aware, a tube can glow and look like its functional when in fact it is bad/non-functional.

Doog wrote:Tubes can still have "gone bad" while still maintaining their glow, so I wouldn't consider that a metric of them being fully functional.

Any joy, Noisy?

Doog wrote:Any joy, Noisy?

No, I tried swapping some of tubes around as suggested, but no joy.

Any recommended east/central London techs, please?