Do fuses make a noise when they blow?

[Supa Scoopa]

My Marshall JCM800 keeps blowing fuses, it started today. Not sure whats causing it, but each time the fuse goes it makes a crackling sound (not from the speakers) and then a really weird smell. Is this what normally happens when you blow a fuse or is it something else going with it.

I have searched.

[Freelancer]

Were you playing it with a guitar or bass? Only version I saw was a 100W guitar head. Is it an electrical fuse or one of the tubes?

[runmikeyrun]

if the fuse keeps blowing you have a problem. Get it looked at by a tech.

[Supa Scoopa]

I play bass and guitar through it, dont think thats the issue. I'm aware it has a problem, but I'm just curious as to whether when a fuse blows does it usually make a noise or is it a silent 'poof' there so goes type thing.

[runmikeyrun]

a few times i've heard a pop but i usually don't hear it because i'm in the middle of playing

[Whothehell1313]

Blown amp fuses typically, and instantaneously, make the sound of silence.

[Supa Scoopa]

It's all good guys, I'm gonna take it to a tech on monday. Probably the output transformer he says.

[T-Bird]

Hi.

First of all, JCM800 is not a particular amp or a cab or even a combo. It's the Marshall line to follow JTM and JMP. The XXXX number, 1959, 2303, 1992 etc. is the model number.

Originally Posted by Supa Scoopa

It's all good guys, I'm gonna take it to a tech on monday. Probably the output transformer he says.

Good call, tech time is always advisable when something blows. Epecially when ever there's smell/smoke/sparks/flames involved.

However, I wouldn't say the most likely cause is the OT, but a shorted (output) tube. Fortunately there's a user friendly and a safe way to test whether the tubes are the most likely culprit or not.

Just mark the location of each tube ON THE BASE, NOT ON THE GLASS and gently remove each. The power tubes have to be removed as a set, the pre-amp tubes can be pulled individually to pinpoint the troubleshooting.

If the fuse(s) doesn't blow with all the tubes removed or just the pre-amp tubes installed, the power tubes or the OT are the most likely causes of the malfunction, the tubes being more likely. IME anyway.

Regards
Sam

[Supa Scoopa]

Yes sorry, its a JCM800 2203 100w, the head. unfortunantly I am out of fuses so I cant do any testing, but thank you for the information t-bird.

[teemuk]

If it makes crackling sounds, and especially if it smells, then it's likely something far more expensive than fuses.

[JimmyM]

Originally Posted by T-Bird

Hi.

First of all, JCM800 is not a particular amp or a cab or even a combo. It's the Marshall line to follow JTM and JMP. The XXXX number, 1959, 2303, 1992 etc. is the model number.



Good call, tech time is always advisable when something blows. Epecially when ever there's smell/smoke/sparks/flames involved.

However, I wouldn't say the most likely cause is the OT, but a shorted (output) tube. Fortunately there's a user friendly and a safe way to test whether the tubes are the most likely culprit or not.

Just mark the location of each tube ON THE BASE, NOT ON THE GLASS and gently remove each. The power tubes have to be removed as a set, the pre-amp tubes can be pulled individually to pinpoint the troubleshooting.

If the fuse(s) doesn't blow with all the tubes removed or just the pre-amp tubes installed, the power tubes or the OT are the most likely causes of the malfunction, the tubes being more likely. IME anyway.

Regards
Sam

agreed. it could also be a rectifier tube. my fender super reverb's rec tube went out on me recently. usually they last forever but now and then they do go. so i'd do your test, but i'd try it with just the rec tube in there before proceeding to the power tubes.

[Jim C]

Originally Posted by T-Bird

Hi.

Just mark the location of each tube ON THE BASE, NOT ON THE GLASS and gently remove each. Regards
Sam

Sam, why can't you write on the glass?

[billfitzmaurice]

Fuses don't smell when they blow, and they seldom make noise. Fryed components, the reason why the fuse blows, do. Putting in fuse after fuse only compounds the damage.

[teemuk]

^ This. In rare occasions fuses may fail by themselves for no apparent reason, or at least without any reason relating to amplifier fault. But if after a fuse failure the replacement fuse fails as well then it's because the amplifier is damaged and fuses are doing their job. BUT the job of fuses is not so much protecting your amp is it is preventing hazards caused by heat effect of high current flow, that is hazards like component meltdowns or even house fires. So, throwing in fuse after fuse, while hoping the problem miracly fixes itself, is pretty much just pouring gasoline to the fire: from each moment you power up the amp to following fuse failure the fault gets to do further damage inside the amp. The noises and smell are a symptom of that; something's frying or arcing inside and something is burning or melting.

Take it to a tech.

[T-Bird]

Hi.

Originally Posted by Jim C

Sam, why can't you write on the glass?

With correct ink, You can. Writing and labeling the base, and the base only has been the standard advice for as long as I can remember.

5881's, etc. and pre-amp tube markings have to be written on glass, obviously. There's tales of incorrect ink and even fingerprints shattering the glass, but in the 25 years I've been around tubes, I haven't personally witnessed such a thing to happen.
I do wipe the glass after installing, and I don't write on the glass though. Just in case .

And then there's the people who insist on using duct tape or painters tape for the labels... Perfectly safe they say.

Regards
Sam

[Jim C]

I was thinking a Sharpie marker
Ironically, there are a 1/2 dozen 12ax7's on the dining room table that I wanted to either date code or add a note about performance; have not done this before adn was regretting thinks like tube test data
Think that this potential to shatter glass would only be applied to power tubes?
Never heard this theory before but who knows?

[agedhorse]

A (mechanical) crackling sound on a high voltage product along with a fuse that blows usually points to a failure of the high voltage insulating system (tube socket, wiring, output or power transformer) and should be serviced ASAP. Continuingto replace fuses will likely increase the amount of damage.