Restoring a vintage Wurlitzer keyboard is a detailed process that requires both mechanical and electronic fixes. The good news is that Wurlitzers were built to be serviced. Even the oldest Wurlitzer keyboards have the potential to become highly playable, reliable instruments with a unique and musical voice.
These are some of the steps that we follow when servicing a Wurlitzer.
Cleaning. This is an important first step because a good deep clean allows us to perform the rest of the work in a non-hazardous, dust-free environment. We remove everything from the case of the Wurlitzer in order to reach every crevice. This includes the keys, the keybed, and all mechanical parts. Because any piece of debris that lands on the reed bar can create noise problems, it is important to reach behind and underneath components to eliminate as much dust and grime as possible.
Inspection. Once the Wurlitzer has been cleaned and emptied of all mechanical parts, we can locate and address any structural issues. In many cases, just the process of unscrewing and removing parts highlights hidden problems. We take note of missing wooden components, third-party modifications, non-original screws, and concealed areas of damage.
We evaluate the mechanical parts at many points during the restoration, but this step is our first and best opportunity to give them a visual inspection. If a component is largely functional and shows only minor signs of wear, we leave it original. Otherwise, we replace it. This includes hammers, whips, and dampers, as well as felts and grommets across the keyboard.
Mechanical restoration. Mechanical restoration varies from keyboard to keyboard. Below, we’ve listed some common issues for various parts of the mechanical action.
Keybed. It is not uncommon for the keybed to display water damage, since liquids can easily be spilled there. In that event, we remediate any lingering evidence of moisture and replace the balance rail felts. We may also replace the balance rail felts if the original felts are very compacted. Finally, we polish and lubricate the balance rail pins.
Keys. Replacing worn key bushing felt often improves the feel, particularly if the keyboard has seen a lot of use over the years. Keyboards with humidity or moisture damage almost always benefit from new key bushing felt. We also typically replace key cloth, which helps ensure consistent regulation.
Hammers, whips, and dampers. Before re-assembling the keyboard, we lubricate the action centers of the hammers, whips, and dampers. In most cases, we find that replacing jack springs improves touch response and helps the keys return consistently. Jack felt is also often worn and benefits from replacement. We also check the felts for loose fibers, and brush splinters from the wooden parts. These small pieces of debris can dislodge and find their way to the reed bar, shorting it or otherwise becoming a source of noise.
Damper felts. Over time, repeated contact with the reeds can wear a groove into the damper felt. This causes the dampers to become less effective at muting the reed, so that the note continues to ring even after the player has released the key. In this case, the damper felts often must be replaced.
Regulation. Regulation involves adjusting the position of the keys and mechanical action to ensure that, whenever a key is depressed, the entire assembly not only moves consistently but returns to its original position once the key is released. This is accomplished by adjusting the capstan screws, the damper screws, and adjusting the paper shims beneath the keys.
Regulation is very important to the playability and touch-responsiveness of the keyboard. It can also affect the keyboard’s tone. A poorly regulated keyboard will have notes that play at slightly different volumes despite being hit with the same amount of force. It also may have notes that buzz or sound dull.
Electronic restoration. Restoring the electronics involves replacing out-of-spec components, reducing hum, and ensuring that all features of the amplifier are working correctly. Every Wurlitzer requires a different level of attention to the electronics, which may include:
Replacing filter capacitors and other electrolytics. Electrolytic capacitors deteriorate over time, sometimes to the point where they are visibly bulging or leaking. The electrolytics in the filter section in particular are subject to additional stresses and can introduce hum into the circuit as they fail.
Replacing deteriorated wiring harnesses. In a 100- or 700-series Wurlitzer, the wiring harness can be a source of noise. Replacing it, or at minimum re-routing the wires so that signal and power wires are safely apart, can reduce a significant amount of hum in many keyboards.
Enabling or repairing vibrato circuits. The vibrato in student-model Wurlitzers was disabled in the factory. However, because all Wurlitzers of the same model used the same amplifier, enabling the vibrato is a non-invasive mod. Alternatively, in Wurlitzers that came stock with vibrato, non-working vibrato is somewhat of a common problem because components in the vibrato circuit have relatively close tolerances. Components that drift out of spec can cause the vibrato to stop working. Replacing those components is typically enough to get the vibrato back up and running.
Repairing non-functioning amplifiers. Many Wurlitzer amplifiers are capable of being repaired. Many older electronic components tend to wear out over time, and benefit from being replaced. In tube models, modifying the wiring can reduce the noise floor.
Tuning. The pitch of a Wurlitzer reed is set with a pyramid-shaped lump of solder attached to the end of the reed. Tuning it requires either filing away or adding more solder. Additionally, Wurlitzers in well-used condition often have mismatched reeds of varying quality that were installed as replacements over the years. A complete tuning involves removing inappropriate reeds and replacing them with reeds that were specifically meant for the Wurlitzer model in question.
Cosmetic restoration. Although we appreciate the history that is written in the flaws of a well-used vintage keyboard, we occasionally repaint and/or re-tolex keyboards that are in extremely poor condition. We also try to bring the keyboard into its best light by deep cleaning the exterior, de-rusting legs and other chrome parts, replacing disintegrating bits of plastic and ensuring that all visible screws match.
Further Reading
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