Turned my amp on for 5 seconds with no load today

[Random Hero]

I was reconnecting it after checking the wiring inside my IV, turned it on, realised after 5 seconds or so that I hadn't connected the cab, turned it off. It works fine, but could I have done any serious damage?

[MattB]

As long as you weren't playing through it for a while you should be fine. 5 seconds is nothing. Especially if it was one of the MESAs in your sig.

-MattB

[Adwex]

If no signal was going into it (you weren't playing), no damage done.

[Random Hero]

Nah, I didn't even have a guitar plugged into it. I literally had just plugged it into the wall, turned it on, went looking for the footswitch jack, saw the speaker cable draped across the cab, realised what I'd done, panicked, turned the amp off.

In that order :)

[Random Hero]

I should add, it didn't even get switched off of standby. Just power to full power, Standby was still in the off position.

[GuitaristZ]

oh thats bad...I think you might have caused a huge increase in global warming...soon the whole earth will explode into fragments, and then glob together to make a celestion ripoff speaker, a marshall amp, and a duesenberg guitar...

[Random Hero]

oh thats bad...I think you might have caused a huge increase in global warming...soon the whole earth will explode into fragments, and then glob together to make a celestion ripoff speaker, a marshall amp, and a duesenberg guitar...

:(

I take it I did no damage at all then.

[brad347]

I should add, it didn't even get switched off of standby. Just power to full power, Standby was still in the off position.

Then there is absolutely no way you possibly could've damaged anything.

[Random Hero]

Then there is absolutely no way you possibly could've damaged anything.

Oh, good. :) I thought you still could even if it was just on standby, but I was clearly mistaken.

[John Phillips]

As long as you weren't playing through it for a while you should be fine. 5 seconds is nothing. Especially if it was one of the MESAs in your sig.
Be careful before you assume that's true of all Mesas... Dual Rectifiers are unstable with no load and will self-oscillate at full power - really not a good idea.

Some other amps are too - I think the Mark series is OK though.

And yes, if the standby was set to 'off (mute), you couldn't have done any damage anyway.

[Random Hero]

Thanks.

As a point of curiosity, what does putting the amp on standby actually do? Just warm up the tubes?

[brad347]

it turns the "filaments" or "heaters" of the tubes on without supplying the high voltage. The filaments should have a chance to warm up and boil electrons off the cathode before high voltage is applied, or tube life will be shortened. This is the function of standby.

Honestly, the whole amp is nothing but a string of lightbulbs until you flick the "standby" switch to its "play" position.

[Random Hero]

So the reason the amp isn't gonna be damaged doing what I did is because basically the transformer wasn't seeing any power?

[John Phillips]

Yes, exactly.

[odourboy]

Ya - without Standby on, there's NOTHING going to the OT/speaker.

[Random Hero]

Thanks guys.

[justonwo]

When I was going through a long troubleshooting process with my Super Lead using a signal generator (JP, you remember that mammoth thread, right), the speaker cable was accidentally knocked out of the jack while the amp was running near full power. Of course, since I was running into a dummy load, I didn't hear that the cable had been unplugged.

It probably took 20 seconds for me to realize why the signal on my scope looked so funky.

The transformer survived. I tested it to make sure there were no shorts, and the turns ratio came out as expected when applying a low voltage AC signal to the secondaries. The amp still plays and sounds great, so I guess I was really lucky.

At any rate, with the standby flipped off, there's no way to damage the OT.

[John Phillips]

If you were running a clean sinewave, that's probably why you got away with it - it's less likely to generate nasty flyback voltages than a clipped waveform.

I probably shouldn't admit this :), but I've accidentally done stuff like that occasionally too. Never blown anything other than a fuse...

Probably the worst was the first time I came across an amp which was unstable with no load - a 60s Vox AC50, which I had sitting on the bench with nothing connected while I fiddled around with something. I noticed a strange whistling noise coming from the OT itself, and heard the tubes 'crinkling' as they overheated. It must have been like that for a good thirty seconds or more before I realised the danger and shut it off. I count that as a lucky escape, old Vox transformers are quite weak.

I think some transformers are just destined to fail more easily than others though. I once had a 70s Marshall in that was blowing tubes every gig or so... it turned out to be a loose impedance selector. I had a voltmeter on the power tube plates expecting to see a voltage drop (thinking the fault would be a short, and looking for the bad tube), but found it spiking upwards in excess of 1KV. Still didn't blow the transformer.

[brad347]

kinda like those old ladies that eat bacon cheeseburgers 3 meals a day, smoke 4 packs of cigs and drink a fifth of bourbon and have still somehow made it to 80 years old :)

[BJF]

kinda like those old ladies that eat bacon cheeseburgers 3 meals a day, smoke 4 packs of cigs and drink a fifth of bourbon and have still somehow made it to 80 years old :)

Hi

Yes

http://www.youtube.com/watch?v=q2A6UJEj81k

Woops yes, better watch those impedanceselectors on old Marshalls.

And yes that is a funny sound when tubes fry and transformers whistle:crazyguy
Have fun
BJ
Affiliations
www.bjfelectronics.com
www.mpamp.com
bjfelectronics@mac.com

[MattB]

Be careful before you assume that's true of all Mesas... Dual Rectifiers are unstable with no load and will self-oscillate at full power - really not a good idea.

Some other amps are too - I think the Mark series is OK though.

And yes, if the standby was set to 'off (mute), you couldn't have done any damage anyway.

Yes you are right, I was referring to the Mark Series.

[Random Hero]

I actually did this again today. This time I switched the amp on fully, but thankfully realised pretty sharpish again - around 5 seconds. Seems like there was no damage done as it sounds fine, but it sure is scary...

I was messing around with both of my heads, switching them around, and this is what happened. Note to self: Take more care.


But anyway, if it sounds fine, it's not likely I've done any damage is it?

[alltone]

kinda like those old ladies that eat bacon cheeseburgers 3 meals a day, smoke 4 packs of cigs and drink a fifth of bourbon and have still somehow made it to 80 years old :)

http://i303.photobucket.com/albums/nn150/douglasamps/Unknown.jpg


:banana :BOUNCE

[Random Hero]

lol ^

FWIW, I did play my guitar briefly. Some light strumming, with the amp's output on about 1.5, if that.