Revox A77 Parts Reference: Order Numbers, Board Map and Replacement Parts

The Revox A77 was built from 1967, and a great many are still being restored. The obstacle is rarely the work itself. It is finding out what a part is called, what number Revox gave it, and whether the number in front of you belongs to this machine at all.

This page is the reference for that. Two tables, each with a search box: the ten circuit boards with their order numbers, and the complete replacement parts list across eleven factory sheets. Type a number or a name and the table narrows as you type.

Every row is present in the page. The search box only hides rows from view, so a search engine, an offline reader and anyone who copies this page still has the whole list.

How A77 order numbers are built

The A77 family prefix is 1.077. Its successor the B77 uses 1.177, which is why a number quoted on a forum can look almost right and belong to the wrong machine. Check the second group before you order.

• 1.077.xxx assemblies and parts specific to the A77
• 1.011.xxx, 1.021.xxx, 1.116.xxx, 1.736.xxx sub-assemblies and heads shared across models
• 20.xx.xxxx, 21.xx.xxxx, 22.xx.xxxx, 23.xx.xxxx, 24.xx.xxxx hardware: screws, nuts, washers, retaining rings
• 33.xx.xxxx, 51.xx.xxxx, 55.xx.xxxx, 71.xx.xxxx, 89.xx.xxxx bought-in items: locks, lamps, micro-switches, loudspeakers, erase heads

A trailing pair such as 1.077.155-03 identifies a variant within the same part number. On the head shields the last pair is what separates the two-hole from the one-hole head fastening, and those are not interchangeable.

The ten circuit boards

The A77 is built as plug-in cards. Naming the card is most of fault-finding, because once you know which card is wrong you can lift it out and work on it at a bench.

Set against the B77, the pattern is the same and only the family digits change. Someone who knows one machine can read the other.

Replacement parts list

Eleven sheets, 226 line items, 204 distinct order numbers. PL is the sheet in the factory parts list and Index is the callout number on that sheet's illustration. Quote both the order number and the part name when sourcing, which is what the factory list itself asks for.

Reading the head numbers

The head block is the part of this list worth slowing down over, because one wrong digit buys a head that will not fit or will not play your tapes.

Two things vary independently. Track format: two-track and four-track heads carry different numbers throughout. Head fastening: earlier machines use a two-hole mounting and later ones a one-hole mounting, and the shields, base plate and screws all change with it. Search for the word Head in the table above and the pairs line up next to each other.

What is verified and what is not

These numbers are transcribed from the factory service manual for the A77, eighth edition, printed in Switzerland in November 1976. They record what Revox fitted.

They do not tell you which revision your machine is. The A77 was built for well over a decade with running changes, and the factory issued separate correction sheets for exactly that reason. Before you order, compare the part in your hand against the entry. Where the two disagree, your machine is right and the list is describing a different year.

Photographs

Photographs of an A77 taken through a complete disassembly accompany this reference. They are free to copy and reuse: see the terms for reusing these photographs.

If you are restoring one of these machines and you confirm something this list gets wrong, or record a variant that is not here, send it. It will be credited to you and added.