The third category is replacement PCBs . These are modern boards on quality FR4 fiberglass, double sided with solder masks and silkscreens. they fit in the same spaces and circuit board holders as the Thomas Vox original PCBs did, but they take advantage of modern layout techniques to eliminate the majority of the infuriating mess of wires inside the amp. They were designed to make the wiring as short and direct as possible, and to make it easy to raise the PCB to access the bottom for servicing the amp in the future. In some cases, modern parts have allowed subsuming much of the off-PCB circitry, like man yor all of the power filter caps. For instance, on models with off-board relays, the PCBs have places for modern PCB mount relays, about $2.50 , instead of the older chassis mount style which may be unavailable at any price. There are currently replacement PCBs for the entire line of Viscount, Buckingham, Royal Guardsman, and Beatle, excepting theV11*3 range. There are also boards for the Cambridge Reverb, Berkeley II, Berkeley III, Pacemaker, and Pathfinder. Each board has its own instruction manual with parts lists, population diagrams, schematics, suggested substitutions and hints about how to fix the rest of the amp on the Viscount/Buckingham/Guardsman/Beatle models with a separate power chassis. Contact me for informaiton on replacement boards. I'll try to help you figure out whether this is the best path for you or not.
The entire purpose of this site is to help people repair their Thomas Organ Vox amplifiers running and out of the landfills. Many amplifier repair techs will simply refuse to work on these amps, often from a lack of knowledge about them. I hope that providing some knowledge will enable more amp techs to take these on, or help electronically-capable owners take on the job themselves.
There are three major help platforms: the Vox Owner's Safety Net, repair manuals in the form of Repair Supplements per model, and new manufacturedprinted circuit boards which retrofit the old PCBs with entire new replacement boards.
The first step is the Vox Owner's Safety Net. This is a 160 page book giving an overview of the Thomas Vox line of amps, with technical descriptions of the circuits involved and how they work. An amp tech might be able to repair your Thomas Vox amp with just this as a background reference. Thomas re-used the same circuits in a mix-and-match fashion to make their amps, so understanding a few things make you more capable of understanding them all. The book is available for printing on demand.
The second set of repair knowledge is the set of Repair SupplementsThese comprise a set of detailed service literature per amplifier model The are NOT just copies of the Thomas Organ schemetics and parts lists. Each is a complete technical manual, with analysis based on the Thomas Organ literature, but checked agains some experienced technical analysis of the circuits, simulation of the circuits and experimentation on actual Thomas boards. This turned up a number of mistakes in the Thomas service literature - like service voltages that just can't be right - and parts lists containing modern substitutions where the original part either is not available any more, or where a modern part is better. In addition, there is a Repair Supplement containing the schematics for all of the Thomas Vox footswitch assemblies. These were frequently lost or broken, but it's entirely possible to repair them, or build a replacement from modern parts. It also contains info on modifications - like LED indicators and replacements for the old incandescent light indicators.
This page is a baby-steps page, so bear with me on anything that's missing or broken. Better yet, tell me what's amiss so I can fix it!! Hit the contact link to send email.
The link to tech tips and resources leads to some additional information I've generated in the past about how to fix and enhance your Thomas Organ Vox amplifier.