Otari MX-5050
MX-5050 B-II›Service

Generation

FirstMark IIBB-IIMARK IIIB-IIIMARK IV

MX-5050 B-II

OverviewIdentifySpecsHistoryDocumentsService

Machines

BII-2BII-4BII-FBII-2E

Servicing the MX-5050 B-II

The factory manual↑ TOP

Two Otari books, both scans:

  • Instruction manual OS3-038 (PDF) — one book for all four machines, the BII-2, BII-4, BII-F and BII-2E. Its Section IV has a short electronic trimming (bias, record level, record EQ) and Section V the full amplifier adjustments.
  • Alignment procedures, Edition 2, January 1988 (digital edition) — "MX-5050 BII and MX-5050 MKIII-2 Alignment Procedures", one procedure for the B-II and the MARK III/2: speed calibration, record and reproduce alignment, and head zenith, wrap and azimuth.

Alignment↑ TOP

Start from the 1988 alignment procedures — section 2.1 for the B-II's speed, 3.1 for access to its amplifier, and 3.3 and 3.4 for reproduce and record — or from OS3-038's Section V, Amplifier Adjustments (p.5-1, PDF p.49). The shared method, with modern test gear, is at Calibrating the MX-5050; its pot numbers are the first generation's, not the B-II's.

How it differs from the shared method↑ TOP

  • Set at 7½ and 15 ips, NAB, 250 nWb/m. The 1988 procedures run speed calibration and record/reproduce alignment "at 7-1/2 and 15 ips with NAB equalization at 250 nWb/m reference fluxivity", biased for Ampex 456 (p.1, PDF p.3).
  • One speed pair per machine, set by a switch. A B-II runs either 15 and 7½ ips or 7½ and 3¾ (OS3-038 p.1-5, PDF p.15); converting it "requires only that you switch the speed selection switch" (section 6.4, p.6-6, PDF p.70).
  • NAB or IEC from the rear panel. Both equalisers are switchable on the rear panel, but after a change the record and reproduce EQ need fine tuning (OS3-038 p.1-3, PDF p.13).
  • A direct-drive capstan. "DC servo motor (Direct drive) for the capstan" (OS3-038 p.1-2, PDF p.12).

Sources↑ TOP