The internet is great, we can have access to information about anything ever created, 24/7 anywhere you are. It is however easy to be bombarded with views opinions and rogue advice when it comes to repairing equipment, much like when you look up your symptoms when you are under the weather. Statistically it is easy to find many people who have had a similar experience as you in just about anything.
With forum upon forum, Facebook and every other social platform there will always be people who think they know what goes on inside you amp through a slice of single serving knowledge.
When we see this sort of thing, we instantly think about what steps have been made to identify the issue, external factors to cause the issue. For example, overheating, mechanical stress, genuine part failure. Annoyingly, despite this there is still always someone who says, “No none of that, I’m standing by my guns, I read on a forum it’s a capacitor or something causing the issue…. I’ve read it’s a common problem”
The problem we have found with the internet because it is written in computerised text is easy to believe that it is the truth.
So that you can avoid being caught up in the forum fun we have explained below some of the essential parts of amps and what they do so you can apply this to your potential problem.
Capacitors get all the bad press. Got a fault with an amp, could be a capacitor. Car not working oh it could be a capacitor. We think the reason capacitors have this reputation is from the days of old Valve amps. A capacitor is essentially two bits of metal/ foil separated by a insulator known as a dielectric. In valve amps one of the capacitor’s jobs is to isolate the high voltage from the signal. As you can imagine this is quite a stressful job as the voltage levels can range from very low to very high. Any breakdown of this part is going to cause issues. When a capacitor starts to fail symptoms could include hearing the pot get very scratchy or a prominent undertone hum would be heard. Unfortunately the ‘old school’ guitarists always jump to this being the first issue. Capacitor or not, we are more than happy to take a look.
Resistors are designed to limit current. How? They pass through enough current that they need and dispose of the rest. How do they get rid of what they don’t need? Heat! The larger white ceramic and other such resistors are designed to dissipate excess current through heat. That is why they’re often mounted off the circuit board to permit flow of air around them. Other ways include mounting them flush to the circuit board but providing a big copper track underside to act as a heatsink.
The placement of the resistor is questionable but unfortunately there is not much we can do about the design of the layout. Resistors getting hot is part of the normal function of the amp or piano. The sometimes they get so hot they can actually unsolder themselves which is where you would need to book in with us!!
So let us just settle one thing… It’s not an inconvenience that the fuse has blown and that it’s a faulty fuse. The purpose of the fuse is to prevent overcurrent and overload situations. The number of enquiries where we get told the fuse has blown and shouldn’t it be made to blow at more amps… We the answer is, well no not really. It’s done it’s job your amp isn’t a smouldering mess on the floor, that pesky fuse blew causing you so much inconvenience in stopping your noises actually saved you. It gave up it’s life in a single shot.
Did you know?
weirdly a fuse is installed as a safety feature, and designed never to actually blow under normal use!! Strange huh!
How to stop blowing a fuse? Raise the size until it stops?
Ideally getting to the bottom of the issue of what is causing the overload. This would require isolating parts of the circuit until the overload is found and repaired.