Servicing the Mark II

The factory manual↑ TOP

The Mark II's books are the ones Otari printed for the 2SD₂ and ½QXD — the designations a period copy of the maintenance manual hand-relabels "MKII-2" and "MKII-4". The same two books also cover the first generation's QXD and 8SD.

• Maintenance manual OMM-1002E (digital edition) — performance tests and electronic alignment in Chapter 3.
• Instruction manual OIM-1004E (digital edition) — the operator's book, with a short alignment of its own in 4-3: standard reference level, bias and record equalisation.

Alignment↑ TOP

The factory procedure is OMM-1002E's 3-5 Electronic Alignment and 3-6 Record and Bias System Adjustment. The shared method, with modern test gear, is at Calibrating the MX-5050; its pot numbers are the first generation's, not these.

How it differs from the shared method↑ TOP

• Different step numbers. OMM-1002E numbers its steps differently from the first-generation manual that the calibration page follows, and has no VU meter calibration or maximum reproduce level step in 3-5 (3-5). Carry the procedure across, not the numbers.
• Two extra record-side steps. 3-6 adds a bias buffer amplifier adjustment and a test oscillator level calibration.
• The same speed pairs. High-speed models — 2SHD₂ and ½QXHD — run 15 and 7½ ips; low-speed models — 2SLD₂ and ½QXLD — run 7½ and 3¾ (OIM-1004E, Table 1-2).
• A DC-servo capstan. The transport has "a dc servo control motor for the capstan", with a pitch control on the transport face (1-1-(1)).
• Equalisation is changed by soldering. The speed pushbutton also switches equalisation (1-1-(1)); changing between NAB and CCIR means resoldering terminals on the equalisation board inside the amplifier chassis (1-1-(2)).

Sources↑ TOP

• Maintenance manual OMM-1002E — 3-5 and 3-6 (alignment steps). The scan is at /manuals/otari-mx5050-2sd2-qxd-8sd-maintenance-manual-omm-1002e.pdf.
• Instruction manual OIM-1004E — 1-1-(1) and Table 1-2 (capstan, speed pairs, equalisation switching), 1-1-(2) (NAB/CCIR change), 4-3 (operator's alignment). The scan is at /manuals/otari-mx5050-2sd2-qxd-8sd-instruction-manual-oim-1004e.pdf.
• The relabelled OMM-1002E cover is described on the Mark II's Identify page.