If your tube (or solid state) amplifier is not “turning on,” the cause of this problem could be a blown line fuse. The line fuse, also referred to as a mains fuse, is the fuse that stands between the main AC power and your power transformer. In an otherwise functional amp, the main fuse can and will blow when there is a problem between the wall outlet and your power transformer (PT). A fuse can also blow when there is a short somewhere in the amp. In either case, the fuse is doing its job when it blows and is protecting the amp by stopping it from running when there is a problem present that could harm the amp’s circuit.

All tubes follow the same basic principles. Inside a tube’s glass enclosure, you have 1) a vacuum and 2) at least two electrodes (but often more, depending on what type of tube we’re talking about). Each electrode has a specific job: either releasing electrons, attracting electrons, or slowing down or speeding up the flow of electrons. We’ll talk about these jobs later. For now, the main thing that tubes are intended to direct electrical current from A to B in some way that is useful to the circuit.

The only true difference between 140-series and 145-series Wurlitzers is the amplifier. Both keyboards were released in the 1960s and represented a total redesign of the Wurlitzer electronic piano. Wurlitzer overhauled the mechanical action, revised the cabinet, and — for the first and only time — manufactured two parallel styles of amplifier: a solid state amp (the 140/140a/140b) and a tube amp (the 145).

Tube amplifiers (and many solid state amplifiers) contain high voltages. Like any reasonably dangerous household object, you should certainly respect your tube amp. However, you don’t have to be afraid of it. If the amp is unplugged and the chassis is screwed in, it is safe to perform basic maintenance like replacing mains fuses and swapping tubes. In fact, fuses and tubes are accessible from the chassis because they are intended to be replaced by the user.

If your amp makes no sound, it is first important to define what you mean by “no sound.” To that end, the first test you should perform is whether you can hear anything coming from the speakers. (This is, of course, after you have eliminated the possibility of trivial problems.)

Listening to what (if anything) comes out of the speakers can help you isolate the problem to specific parts of the circuit. If you hear no sound coming from the speakers — including hum, hiss, reverb crash, input cable pop, or any other incidental, non-musical sounds — the problem could be the speaker itself. But, if you hear non-audio sound coming from the speakers, the problem is likely, although not guaranteed, to be a fault in the preamp section of the circuit.

If your amplifier isn’t working, the best thing you can do is describe the problem as accurately as possible. If you’re into DIY, using accurate terms will help you google your problem and give you the best search results. If you’re asking a tech or a friend for help, describing your problem with specificity helps them offer more relevant suggestions.

Cathode bypass capacitors are not absolutely necessary in a circuit. However, their presence or absence in an amplifier affects three things: gain, frequency response, and hum.

If you feel that your amp is lacking in any of these aspects, determining whether the cathodes are bypassed is a good place to start.

The filter capacitors in many amps are mounted in a metal can, which can be an obstacle to successfully recapping the amp. These days, filter cans are only made in a limited values, so it's hard to find the exact match. Mounting the caps outside of the can is another option, but finding the space can be tricky. Removing the can can leave a giant hole, which can allow dust to enter the chassis over time. So, what's the best way to replace can-style filter capacitors?

In the classroom, multiple student-model Wurlitzers were connected to each other via the two ports on the back. This connection allowed each Wurlitzer to communicate with the teacher console. It also linked each Wurlitzer to the mains wiring so that they could power on in the first place.

When we’re thinking about buying a Rhodes, there are a few criteria that we use to judge potential purchases. We’re mostly concerned about how much work the Rhodes needs to become playable - and if you want your Rhodes to be a functional keyboard and not just a moderately inconvenient buffet table, you probably care about the same things we do.

In Part I of our guide on fixing hum, we listed some easy fixes. In Part II, we’ll go into further detail on techniques that require some prior electronics experience to execute. It’s worth checking out Part I first, because it listed some simple, non-invasive things that you should always be tried before diving into the amplifier’s circuitry. For the purposes of this article, we’ll assume that you already tried everything in Part I. This includes:

Before we start, a disclaimer: hum should be addressed on a case-by-case basis, because every vintage amp is special and degrades in its own way. What cures one amp may not work for another. That said, reading this guide should give you a good starting point on how to address your own hum problems. This guide is pretty basic and going to assume that the only piece of test equipment that you have is a multimeter.

The heaters of your vacuum tubes are one of the most critical parts of your amplifier. A well-designed heater circuit is quiet and unobtrusive: truly an unsung hero of any quality amp. On the other hand, flaws in a heater circuit can produce noise.

Tropical Fish now offers several kits containing replacement components for all Wurlitzer amplifiers. If you already have experience working with electronics, these kits offer a convenient DIY option for restoring your amp. Each kit contains the same high-quality components that we use in our own restorations.

For all amplifiers, we offer the Basic kit as well as several add-on components packages. The Basic kit contains all electrolytic capacitors, power supply resistors, and a few input components for the preamp. For many amplifiers, replacing these components is sufficient for improved reliability and performance.

Early Wurlitzer electronic keyboards dating before roughly 1962 all featured on board tube amplifiers. Tube amplifiers offer a unique warm & full sound and what could be better to play your Wurly through right?  To many, however, a vintage tube amp can appear intimidating, high-maintenance and something only audiophiles should own. In the world of vintage amplifiers, however, a tube amp is more likely to be easier to troubleshoot should anything go wrong with its functionality.  In general vintage tube amps have large easy to check and replace components, while vintage solid state amps often have smaller, more delicate components. 

Fender Rhodes keyboards came with quite a few parts and accessories, many of which are subtle and easy to lose. If you’re unfamiliar with the Rhodes, it can be hard to tell if a keyboard you’re thinking about buying is complete or not.

This Wurlitzer 140a belonged to a producer for many years, and arrived at our shop in well-used condition. By that, we mean that it was pretty banged up and showed evidence of previous repairs. Also, because multiple latches were missing, the lid didn’t attach very well. At some point, it had obviously once been held in place with duct tape.

All Wurlitzer electronic pianos - from the model 112 to the Wurlitzer 200a - are more or less built the same. There are subtle differences in the mechanical action and the amplifier, but they all follow the same basic principles.

When you hit a key on the Wurlitzer electronic piano, a felt-tipped hammer rises and strikes a metal reed. The reed vibrates to a certain pitch, which is determined by the weight of a lump of solder at the end of the reed. A pickup converts the vibration into an electrical signal, which is finally amplified by the onboard amp and sent to a speaker.

Here’s how it works in a little more detail:

The Wurlitzer 206 is the student version of the Wurlitzer 200. It is equivalent to the 200 in every day, but it is mounted on a cabinet instead of legs and some features of the amplifier are disabled. However, all of the components that are in a 200 are also present on the circuit board of the 206. Enabling vibrato and the aux output is therefore as simple as adding some wires and a 10k potentiometer. Here is how we do it.

The Wurlitzer 200 and 200a are extremely similar. If you are trying to decide between the two models, you should first of all realize that there are no bad decisions here. When restored, both types of keyboard are equally reliable, high-quality instruments. And, of course, both of them have that iconic Wurlitzer sound.

If you can’t decide between a Wurlitzer 200 and a 200a, this guide may help. Below, we’ve listed the differences between the 200 and the 200a.