QX / QXD / QXHD

The operator's book for the first-generation rack machines, its cover reading "MODELS MX-5050 2SD₂, QXD, ½QXD AND 8SD". Four configurations across two tape widths: the ¼″ two-channel 2SD₂, the ¼″ four-channel QXD, the ½″ four-channel ½QXD and the ½″ eight-channel 8SD, each in high- and low-speed form. General information, installation, operation, and preventive maintenance, with four fold-out schematic and wiring sheets bound at the back.

This is not the book the Mark II shares. That one is titled "MODELS MX-5050 MKII-2, QXD, MKII-4 AND 8SD", it is the later of the two, and it remains wanted; its slot is below. Both books are first-generation, which is exactly why they are easy to confuse: the QXD and the 8SD stand on both covers. What separates them is the rest of the cover. This one adds the 2SD₂ and the ½QXD, the rack machines with separate transport and electronics, PA-3xx boards, discrete transistors and TTL. The other adds the two desk-top MARK machines. 38 pages.

The service book for the same four machines, and the one that matters on a bench: 117 pages of maintenance procedure, schematics and parts lists. Its own introduction sets out the division of labour — this supplement carries the detailed maintenance information, and the instruction manual above carries description, installation, operation and routine adjustment.

Its shape will be familiar from the Mini Pro's own maintenance manual: test equipment and routine maintenance in Section 1, transport maintenance in Section 2, then performance tests at 3-4 and electronic alignment at 3-5, ending with record and bias at 3-6. The step numbers differ, though. SRL adjustment is 3-5-(4) here where the Mini Pro book puts it at 3-5-(6), so do not carry a step number across from one book to the other.

For the QXD and the 8SD alike, this is the first factory service manual the site holds. The service training binder names both machines, but only in its cross-reference lists.