Every document

First-generation MX-5050 operator's manual — Otari catalog no. OIM-1005E, the book the maintenance manual defers to for installation, operation and preventive maintenance. For a month this card said no scan or listing of it had surfaced anywhere online, and that this page was the open web's only mention of the catalog number. Both were true — and then a paper copy turned up not online but an hour's drive away, through a Tapeheads forum post looking for tape people around Brisbane. Thanks, Chris.

It is an original factory print, not a photocopy — aged cream paper, punch holes and all, the catalog number top right on the cover. 46-page scan at 600 dpi, 46 MB; the full 1200 dpi scan is below. Transcribed in full as a digital edition. Three schematic fold-outs came tucked into the same copy — the TD-5050 tape transport, its DC-capstan sibling TD5050DA, and the AF230A record/reproduce electronics — and each has its own card further down this page.

Otari's data sheet for the one- and two-channel machines: two color pages covering the full-track MX-5050-FL and the half- and quarter-track 2S and 4S — the bulleted selling points, the marketing figures the maintenance manual never gives (input sensitivity, output level, frequency response), and the August 1976 suggested list prices: $1,450 for the FL and 2S, $1,420 for the 4S. The footer names and dates the sheet itself — S111, printed 8-76 — and the introduction points four- and eight-channel buyers to its siblings, sheets S-108 and S-110. “Specification Sheet” is Otari's own term: both tri-fold brochures below defer to this very document — “Full details are in the Specification Sheet” — which is why the pitch lives there and the data lives here, on two pages.

First of the three pieces of sales paper from the same eBay order, each a different document — the other two, a September 1975 tri-fold and its April 1978 re-set, are on this page as their own cards. 2-page scan, 3.5 MB (or the 1200 dpi original below).

The earliest factory sales paper on this site: Otari's orange six-panel tri-fold, printed September 1975 — the "Sensible Alternative" pitch, a tour of the front panel running unbroken across the centre fold, and a Performance Specifications page from the era when the line carried the four-channel QX alongside the two-channel machines (its S/N table quotes both, and the panel photo itself is a QX).

Tri-folds jam a document scanner, so this one went page-by-page on the flatbed at 600 dpi; the two joining pages are reassembled into one spread in the PDFs. 5-page assembly, 6.7 MB (or the full 600 dpi assembly below).

The April 1978 re-set of the same pitch — the familiar sections re-typeset, a Mounting Configurations page with ordering information (MX-5050-FL, -2SH, -2SL and the servo -2SHD), and quietly revised specification figures: the numbers moved between 1976 and 1978, and the differences are traced on the specs page.

Same flatbed story as its 1975 sibling: 600 dpi glass scans, joining pages reassembled — the cover page pairs the blue title panel with the introduction column, the same two-column design as S-111's own cover face. 5-page assembly, 5.4 MB (or the full 600 dpi assembly below).

The first factory sales paper on this site for the half-inch eight-channel machine: four pages pitching the MX-5050-8 at small studios, musical groups, schools and training departments, with photographs of the transport, the stacked eight-channel electronics, the heads and the plug-in boards, and a full specification page — 0.040 in. tracks, 15 and 7½ ips, ±7% DC capstan servo, signal-to-noise 63 dB NAB weighted at 15 ips, transport 64 lb and electronics 55 lb.

The footer names the sheet — S110A, printed 1-78, effective January 1, 1978, from Otari Corporation in San Carlos. It is the S-110 that S-111 sends eight-channel buyers to. 4-page scan, 1.8 MB.

Factory maintenance manual with schematics and parts lists, covering both first-gen transports: the exploded views show the AC belt-drive capstan with its run cap for the 2S/4S, and a DC-servo capstan — drive motor, +5 V supply board, varispeed pot — for the 2SD/4SD. So the DC-capstan sections are the D variants' own documentation, confirmed, not stray B-series material. This is also the factory's service book — its own pages say it is intended for qualified maintenance or service personnel — and Otari published no separate first-generation service manual: the documentation set was this maintenance supplement plus the operation manual above.

Don't look for the transport wiring in here, though: the schematic pages defer to a separate TD-5050(DA) wiring-diagram sheet — both variants of that fold-out, the AC-capstan TD-5050 and the DC-capstan TD5050DA, are now on this page as their own cards. 85-page scan, 34 MB.

Update, July 2026: a paper copy finally arrived — two eBay listings, both delivered — and went through the scanner here at 1200 dpi. Honesty about what that buys: the book itself is plainly a photocopy — an earlier original's binder holes are printed on the pages alongside the ones actually punched through this copy — so the scan preserves a copy faithfully, not an original. It is the best copy this site can offer until a true original surfaces — and it turned out to carry something the cleaner mirror never had: it is a later factory revision whose parts lists fill in the New No. column with Otari's old-to-new part renumbering. The second book from the same hunt, a separate Parts List and Schematics volume, turns out to be this manual's own parts and schematics pages rebound on their own — offered below for anyone who wants just those sheets. Both books also carry the TD-5050 transport fold-out, unscanned: no scanner on this bench fits the sheet, and the separately-sourced fold-out elsewhere on this page is the better copy anyway.

The entire tape transport on a single sheet — this is the schematic that unlocked the dummy plug wiring. Dashed outlines attempt to break the drawing apart into its individual circuit boards, but the sheet encompasses many of them.

The primary download is a vector edition traced from the original factory fold-out that came tucked into the paper operation manual above — razor sharp at any zoom and clean for large-format printing, with an OCR text layer so many component designators can be searched (coverage is partial; schematic lettering defeats OCR in places). Vector PDF, 0.8 MB. The cleaned raster, the original-tone scan and the earlier separately-sourced capture are below.

The fold-out that came tucked into the paper operation manual above: “MX5050D Transport Electronics (TD5050DA)”, the DC-capstan sibling of the TD-5050 sheet. The relay and solenoid logic will look familiar from that card, but this drawing adds the whole capstan servo section the AC machines never had — the µA723 regulator, the EM710-007A capstan motor, the speed-select lines and the fix/variable pitch control.

The sheet is wider than any scanner on this bench, so it went through as two overlapping halves and was registered and merged digitally — the join runs through the title line, which reads cleanly across it. The primary download is a vector edition traced from that scan — razor sharp at any zoom, with an OCR text layer so most designators can be searched (coverage is partial). Vector PDF, 0.9 MB; the cleaned raster and original-tone scan are below.

The second of the two schematic drawings the operation manual's front matter promises — listed there as AF-230-101, Record/Reproduce Electronics; the sheet itself is titled “Record/Reproduce Electronics (AF230A)”. Until this fold-out came tucked into the paper copy above, the front matter's note on this site read “still missing”. The whole audio chain on one sheet: both channels' record and reproduce amplifiers, the mic and line inputs, bias and erase, the VU meters and the headphone output — with the notes tables keying the transistor complements and the potentiometer functions by model.

Same treatment as the transport sheets: too wide for any scanner here, scanned as two overlapping halves and merged digitally. The primary download is a vector edition traced from that scan — razor sharp at any zoom, with an OCR text layer so most designators can be searched (coverage is partial). Vector PDF, 1.3 MB; the cleaned raster and original-tone scan are below.

The operator's book for four configurations across two tape widths, its cover reading "MODELS MX-5050 2SD₂, QXD, ½QXD AND 8SD": 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.

The Mark II owner's book too. A period copy of the companion maintenance manual, OMM-1002E, has "MKII-2" and "MKII-4" hand-lettered over the 2SD₂ and ½QXD on its cover — the same catalogue number, the same photograph, the same pages inside. Who relettered it, Otari or a dealer, the copy does not say.

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.

This is also the book sold as the Mark II maintenance manual: a period copy's cover reads "MODELS MX-5050 MKII-2 QXD, MKII-4 AND 8SD", with the two MKII designations lettered by hand over 2SD₂ and ½QXD. Its inside pages match this scan word for word, misprints included.

The 26 schematic and PCB X-ray sheets of the QXHD's Section 7, redrawn as clean sheets: signal flow and interconnection diagrams, the audio boards, the master oscillator and power supply, the tape transport and the capstan motor.

Chris, a QXHD owner in Delaware, redrew them from his own machine and factory books. Two capstan sheets show the speed select as he modified it, and are marked as not factory.

Otari's two-page preliminary sheet for its new two- and four-channel Mark II recorders. The first page introduces the separate transport and electronics, standard DC-servo capstan and optional noise-reduction interface; the second specifies both formats. Its imprint reads S-114-11-76, effective November 1976 — factory paper older than the January 1978 line-up ad previously standing in for this missing document.

A paper copy arrived from eBay and was scanned here at both 600 and 1200 dpi. The two-page digital edition transcribes the features, introduction and complete specifications from the paper scan.

The B's service book, and by its own account half of a pair: “This manual is a maintenance supplement to the MX-5050B series instruction manual, catalog No. OS1-011, and provides detailed maintenance information.” The photograph inside is captioned “MX-5050 Recorder (2-Channel Version)”. 101 pages behind a blue Otari Professional Products cover.

Its list of illustrations runs from lubrication, the tape speed conversion switch and the fuse locations through brake and pinch-roller pressure measurement, the capstan servo control board and the control and recording-process timing charts, to the record and reproduce system diagrams, bias current against output and distortion, the VU meter amplifier board and reel motor mounting. No print date appears on the cover, title page or introduction.

A paper copy arrived from eBay, stamped SERVICE COPY — NOT FOR RESALE in red on its cover, and was scanned here: 98 pages at 1200 dpi, and a cleaned 600 dpi copy for everyday use. The digital edition was transcribed from an earlier image-only scan of 101 pages, kept below.

Otari's wiring sheet for the tape transport T5061 in the B's DC servo capstan machines, the MX5050B-2HD, 2LD, 4LD, FHD and FLD. It runs from the mains inlet and voltage taps through the power transformer T801 (TF11025A) to the control P.C.B. PB-42D: the supply and take-up reel motors with their 6.5 µF, 250 V metallized paper capacitors; the pinch roller and brake solenoids P801 to P803; the power switch board PB-42E with its POWER, REEL, EDIT, SPEED and SAFETY switches; the AUX SW board PB-42F; the LED boards PB-81G and PB-81H; the transport keys and the motion and R.M.S. sensors; the DC servo capstan motor MR5A008 with its VR801 pitch control; the CB102 (CR705A) remote control socket; and the lines on to the amplifier. A parts table lists the solenoids, switches, capacitors and pitch pot by Otari part number.

Scanned here at 600 dpi in three overlapping parts and joined into one sheet. A3 PDF, 3.9 MB.

Otari's wiring sheet for the tape transport T5063 in the B's hysteresis synchronous capstan machines, the MX5050B-2H, 2L and 4L. It runs from the mains inlet and voltage taps through the power transformer T801 (TF11025A) to the control P.C.B. PB-42K: the capstan motor's main and auxiliary 4-pole and 8-pole windings with their C817 metallized paper capacitor (2 + 0.5 µF, 250 V, with a jumper for 50 Hz mains); the supply and take-up reel motors with their 6.5 µF, 250 V capacitors; the pinch roller and brake solenoids P801 to P803; the power switch board PB-42M with its POWER, SPEED (HIGH/LOW), REEL (LARGE/SMALL), EDIT and SAFETY switches; the AUX SW board PB-42L; the LED board PB-81H; the transport keys and the motion and R.M.S. sensors; the CB102 (CR705A) remote control socket; and the lines on to the amplifier. A parts table lists the solenoids, switches and capacitors by Otari part number.

Scanned here at 600 dpi in three overlapping parts and joined into one sheet. A3 PDF, 5.2 MB.

Otari's circuit sheet for the B's transport control board, printed as PB-42D for the MX5050B-2HD, 2LD, FHD and FLD and PB-42K for the MX5050B-2H, 2L and 4L; R701, C701, D701 and FS701 are fitted to the PB-42D only. It covers the transport logic around the M54410P control IC (IC605) with its SN7400, SN7403 and SN7414 gates and 9602 one-shots; the drivers for the relays RL601 to RL607, which switch the reel motors between the transformer's AC 100/80 V, 71/59 V and 47/38 V taps; the pinch roller, supply brake and take-up brake solenoid drivers; the REC COMMAND and REC LED lines; the speed conversion switch SW701; and the power supply, with bridge rectifiers D701 to D705 and the regulators IC701 to IC704 (7805, 7824, 7815 and 7915). A parts table lists the ICs, transistors, diodes and relays by Otari part number.

Scanned here at 600 dpi in three overlapping parts and joined into one sheet. A3 PDF, 5.1 MB.

Otari's circuit sheet for the record reproduce amplifier A1028, printed for the MX5050B-2H, 2HD, 2L, 2LD, 4L and 4LD. A small table on the sheet gives A1028 for the MX5050B-2 and A1034 for the MX5050B-4, with R344/R444 at 1 kΩ and 1.5 kΩ, although the A1034's own sheet is titled for the full-track MX5050B-FHD and FLD. Channel 1 is drawn in full, with channel 2 boxed under its 200 and 400 series numbers. It covers the reproduce amplifier from the REP heads, with its JFET-switched equalization for 3¾, 7½ and 15 ips; the µPC571C line amplifier and the output transformers T101 and T201 (TF21007) to the line outputs and phones; the mic and line inputs and record amplifier, with the NJM4559 and NE5534 op-amps; the record equalizer with its NAB and IEC settings; the bias and erase oscillator around T501 (TF41002); the record relays, the muting relay RL501 and the REC READY logic; and the peak detector and VU meter amplifier PB-13K. Tables list the semiconductors and relays by Otari part number and give the function and drawn position of every potentiometer, variable inductor, switch and relay, from VR101 SEL REP level to SW506 output level.

Scanned here at 600 dpi in three overlapping parts and joined into one sheet. A3 PDF, 7.5 MB.

Otari's circuit sheet for the record reproduce amplifier A1034, printed for the full-track MX5050B-FHD and FLD. It keeps the A1028's two reproduce channels and two line outputs but records one channel: a single line and mic input, one record and one erase head, and the record relay RL301 alone. It covers the reproduce amplifier with its JFET-switched equalization for 3¾, 7½ and 15 ips; the µPC571C line amplifier and the output transformers T101 and T201 (TF21007); the record amplifier and the separate record equalizer board PB-81S with its NAB and IEC settings; the bias and erase oscillator around T501 (TF41006); the muting relay RL501 and the REC READY logic; and the peak detector and VU meter amplifier PB-13K. Tables list the semiconductors and relays by Otari part number and give the function and drawn position of every potentiometer, switch and relay, from VR102 reproduce EQ to VR501 test oscillator level.

Scanned here at 600 dpi in three overlapping parts and joined into one sheet. A3 PDF, 6.9 MB.

The MX-5050B series instruction manual, catalog No. OS1-011, is the book the OS2-004 maintenance manual supplements. This 61-page Library of Congress scan includes installation, operation, preventive maintenance, electronic alignment and schematic sheets. An original paper copy has also been bought and is awaiting receipt.

Otari's fold-out for the new B, effective September 1979 and printed as form 107-9-79 from the Belmont office. The outside face carries the pitch, a full MX-5050-B specification block — three speeds in field-selectable pairs of 15/7½ or 7½/3¾ ips, DC capstan servo standard with ±7% control in record and reproduce, TTL/IC logic for noise-free punch-in, 24 dBm headroom and 28 dBm output — and a strip of other Otari machines that still pictures the Mark II-2 and II-4, beside the MX-7800, MX-5050-8D, QXHD, FL, ARS-1000 and DP-4050. The inside face is the machine itself, called out control by control.

Two pages — 1 and 2 of worldradiohistory.com's Otari catalog bundle. Transcribed in full as a digital edition: the mirror's text sits in a sharp 300 dpi layer, so the words come through cleanly even though its photographs do not.

Otari's combined book for the BII series, and a complete one: general information, installation, operation, preventive maintenance, amplifier adjustments, transport maintenance, performance testing, P.C.B. assemblies and parts lists, exploded views, and a full set of circuit diagrams. Ten sections over 116 pages. Table 1-1 covers all four machines — BII-2, BII-4, BII-F and the DIN BII-2E — and Section VI documents the factory conversion from 15 and 7½ ips to 7½ and 3¾.

This book is also the answer to a small mystery. A 22-page PDF circulates under the filename otari_mx-5050_ii_2_schematics.pdf, which reads as the 1977 Mark II-2 and is not: it is this manual's Section V block diagram and timing chart, its Section VIII board layouts, its Section IX exploded views, and its Section X schematics, lifted out and rebound as a single file. The five schematic sheets in it — A10620B and A10680C rec and repro amp, PB-46Q control, PB-46R timer drive, and the transport wiring diagram — are pages 10-2 to 10-6 here, in that order.

Two copies below. The first has a text layer and is searchable; the second is the image original at ten times the size and slightly better on the drawing sheets. 116 pages either way. This is the sixth edition, issued September 1984, with Otari's Belmont address on its contact page. A later printing with the Foster City address and a June 1989 lubrication bulletin bound in also circulates; the bulletin has its own card.

One-page Otari technical bulletin on speed conversion and adjustment. Its eight steps and two figures repeat section 6.4 of the OS3-038 sixth-edition manual. No issue date is printed on the bulletin. The heading names B and BII, but the procedure explicitly names BII; applicability to the plain B is unconfirmed.

One procedure for two machines, which is what the parts cross-reference on this site would predict: the BII-2 and the MKIII-2 share heads and an audio board. Otari's title page reads “MX-5050 BII and MX-5050 MKIII-2 Alignment Procedures”, Edition No. 2, January 1988. 26 pages: tools and test tapes; speed calibration for each machine and the MKIII-2's capstan servo offset; record and reproduce alignment — reproduce azimuth, 15 and 7½ ips reproduce, peak indicator calibration, bias, record azimuth, input and record level, high-frequency equalization, low-frequency compensation and the oscillator; then head height, zenith, wrap and azimuth.

Everything is set at 7½ and 15 ips with NAB equalization at 250 nWb/m reference fluxivity, biased for Ampex 456. Transcribed in full as a digital edition.

Otari's full-color brochure for the ¼″ two-channel 5050B-II, © 1983 from the Belmont office and designed by Neilson & Anklam. Eight pages of photographs and feature copy, closing on a specifications page with a dimension drawing and the roll-around pedestal Otari offered for every 5050 series recorder.

One of its captions names the MARK III/2, BQ-II, MARK III/4 and MARK III/8 as the B-II's family, which is the evidence the wider-family page quotes. Pages 9–16 of worldradiohistory.com's Otari catalog bundle, which scans this brochure twice; this is the first pass.

Page 8 lists CB-102, ZA-53T, ZA-53S, FC-2B, RK-2B and ZA-52L as options for the two-channel B-II.

Otari's two-sided sheet for the Model 5050 B-II ¼″ two-channel recorder, © 1984, form BP6847K. The back carries the standard features and the full specification grid: 15 and 7½ or 7½ and 3¾ ips as internally switchable speed pairs; four heads in line, a half-track erase, quarter-track play, half-track record and half-track play; wow and flutter under 0.04% at 15 ips; 72 dB unweighted signal-to-noise at 15 and 7½ ips; 25 Hz to 22 kHz ±2 dB at 15 ips; 60 lb — measured on 3M 226 tape.

Pages 21 and 22 of worldradiohistory.com's Otari catalog bundle.

Page 2 independently lists CB-102, ZA-53T, ZA-53S, FC-2B, RK-2B and ZA-52L for the two-channel machine.

Otari's book for the half-inch four-track MARK III: ½″ tape at 7½ and 15 ips, in ten sections over 154 pages — general information, installation, operation, maintenance, routine maintenance and conversion, tape transport maintenance, performance testing and electronic alignment, major component replacement, troubleshooting, and parts lists and schematics. OS3-035 is on the cover and again in the standard-accessories list. The manual prints no date of its own; a drawing near the back carries 22 DEC 1983 in its title block.

It also carries an addendum headed “(MX-5050 BQ-2, MK-3-4, MK-3-8)”: one sheet of changes for the BQ-II and both half-inch MARK III machines together. The copy has a text layer, and every page carries a “Downloaded from www.Manualslib.com” line from the copy it came from.

The book for the BQ-II, the MARK III series' quarter-inch four-track: ¼″ tape, four tracks at 0.94 mm, 7½ and 15 ips. Ten sections in the same order as the MKIII-4 manual, from general information and installation through tape transport maintenance, performance testing and troubleshooting to parts lists, exploded views and pin identification. The cover prints Parts No.OS3-031, Edition No.2, Issued: November 1983 — the catalog number OS3-031 here, OS3-035 for the MKIII-4 book beside it.

A paper copy arrived from eBay and was scanned here: 143 pages at 1200 dpi, and a cleaned 600 dpi copy for everyday use. Behind the pin identification it carries a schematic index dated 12 SEP 1984 listing nine drawings, and all nine came with it: the head connection diagram 4-28961 on the last page; six fold-out sheets, each scanned here in three parts and joined: the tape transport wiring diagram CB3170A (3-7695), the control P.C.B. PB44S0BA (3-8376), the REC/REP amp P.C.B. PB14Z0A (3-8497), the AMP control P.C.B. PB45E0A (3-6649), the mother P.C.B. PB76D0A (3-6287) and the headphone amp P.C.B. PB15A0A (3-6399); and the timer and MIC ATT P.C.B. circuit diagrams 4-28963 and 4-28965 on loose sheets.

The digital edition is transcribed from this paper copy. A second paper copy, the first edition, is scanned here too: 141 pages under the same catalog number, with no edition number on its cover. Its specifications differ from Edition No.2 — signal-to-noise 69 dB NAB and 66 dB unweighted, crosstalk greater than 55 dB, erase greater than 70 dB — and its contact page lists Tokyo, Belmont and Germany only. Those are the figures in the earlier OCR transcription laid out in Word, which the edition was first built from, so that transcription was made from the first edition. It is kept below for reference and carries the OCR's mistakes on its pages.

This site's redraw of Otari's circuit diagram 3-6649 for the BQ-II's AMP control P.C.B. (PB45E0A), the fold-out in the instruction and maintenance manual OS3-031, as a KiCad 10 project. Parts sit at Otari's positions on Otari's wire routes; the printed boxes are re-lettered and their Japanese labels glossed in English.

The project carries its own symbols, SPICE models and test bench, so it opens and simulates in KiCad with nothing else installed. Five simulated scenarios, from the DC operating points through the 1 kHz and 10 kHz test oscillators and the REC command logic with its 555 clocks to the power-on mute, are written up with 226 checks on their own page. It is a simulation of the drawing, not of a physical board.

Otari's ten-page brochure for the MARK III series, © 1984: a page each for the MARK III/2 two-channel, MARK III/8 eight-channel and MARK III/4 four-channel recorders, then remotes, accessories and options, and a comparison grid across the MARK III/2, III/4, III/8 and the upright BQ-II — channels, tape width, speeds, equalization, frequency response, signal-to-noise, and wow and flutter.

Its accessory list says which machine each part fits: the RK-2B rack kit for the BQ-II, the CB-102 remote for every 5050 except the MARK III/8. Pages 33–42 of worldradiohistory.com's Otari catalog bundle.

Opened up as a digital edition: the comparison grid, the feature lists, every remote and accessory part number, Otari's photo captions and the worldwide addresses off the back cover, with the sales copy described rather than reprinted. Two of the three machine pages promise “dynamic breaking”; the MARK III/2 page spells it braking.

The first printing of Otari's two-sided sheet for the Model 5050 MARK III/2 ¼″ two-channel recorder, © 1983 from Belmont. Its performance figures match the 1984 B-II sheet's — the same speed pairs and four-head stack, wow and flutter under 0.04% at 15 ips, 72 dB unweighted signal-to-noise, 25 Hz to 22 kHz at 15 ips — as a machine sharing the B-II's heads and audio board should. It adds a vinyl-covered wood case, the RK-32 rack kit, a 34-pin external control connector and an 89 lb shipping weight.

Pages 7 and 8 of worldradiohistory.com's Otari catalog bundle.

The same sheet reprinted four years on, © 1987, form BP6872.5K — and the figures moved. Signal-to-noise now reads 68, 71 and 69 dB unweighted at 15, 7½ and 3¾ ips, against 72, 72 and 70 in 1983; frequency response is 30 Hz to 20 kHz at both 15 and 7½ ips, against 25 Hz to 22 kHz and 20 Hz to 20 kHz; and the measurements move from 3M 226 to Ampex 456 tape. The features list now describes the external control connector as an interface for SMPTE/EBU time-code synchronizers and editors.

Pages 23 and 24 of worldradiohistory.com's Otari catalog bundle.

Otari's own operation manual for the MX-5050MKIII-2. Its optional-accessory list on printed page 1-5 names CB-102, ZA-54C (CB-116), ZA-51B, ZA-53T, ZA-53S and ZA-52Y for this machine.

This 48-page Library of Congress scan is incomplete: it skips the even-numbered printed pages, jumping from 1-1 to 1-3 to 1-5 to 1-7, for example. Use it for the pages it actually contains, not as a complete operation or service reference. A complete copy remains wanted below.

Otari's guide to wiring its machines to a synchronizer, 22 pages, Edition 1, May 1985. Pages 2 to 5 are the MX-5050's: the conditions for synchronizer use on the BQ-II and MARK III series — tallies low true, tach pulses read in fast wind, capstan speed steered by a DC voltage, and a dummy plug for calibrated speed when the cable is out — then three diagrams wiring the machine to a BTX Shadow: for machines with no locator connector, with the 16-pin locator connector, and with the 34-pin one. The rest of the book covers the MX-70 and the MTR-10, 12, 20 and 90.

The MX-5050 pages are transcribed as a digital edition, with each wiring diagram set out as a table pin by pin and traced to vector. The cover is scanned in colour, the pages at 400 dpi in black and white.

Otari's two-page sheet for the “MX-5050 BIII Analog Two-Track Recorder”, which opens: “The MX5050 BIII has long been the standard in 1/4" 2 track analog recorders.” It lists a DC capstan under quartz PLL servo control, a built-in mini-autolocator, a rehearse function, automatic monitor switching, balanced transformerless XLR inputs and outputs, ±20% pitch in 0.01% steps, the 37-pin Otari parallel interface for synchronizer editing, and a ¼″ deck plate with cast aluminum side panels.

Page 2 lists CB-119, CB-127 and the ZA-52L-22 pedestal for the two-track BIII, as well as transformer and rack options. The pedestal's -22 suffix is retained because the earlier series literature prints only ZA-52L and does not explain the variants. The footer reads “© 1999, 2008 Otari, Inc.”

One book for two machines in two different boxes: the cover reads “MX-5050 MKIV-2, BIII-2 Master Tape Recorder Operation and Maintenance Manual”, so the desk-top MKIV-2 and the upright BIII-2 share it. Nine sections over 145 pages — introduction, installation, controls and indicators, operation, maintenance, transport adjustment and parts replacement, audio alignment, specifications, and exploded views and schematic diagrams. The standard-accessories list names the manual itself as OS3-298. The cover names two machines; section 1.1 covers five.

This is the fourth edition, printed December 1997. Most page footers are dated May 1992, and the pages revised for this edition carry December 1997 — moving the last generation's paper trail on this site forward six years from Otari's 1991 series data sheet. The copy has a text layer and is searchable.

Transcribed in full as a digital edition, checked word by word against the file and page by page against the printed page.

The third edition of OS3-298, printed May 1992: a 149-page Library of Congress scan with operation, maintenance, parts lists and schematic diagrams. Held alongside the fourth edition of December 1997. Section 1.1 names the five models covered: MKIV-2, MKIV-2E, BIII-F, BIII-2 and BIII-2E. The MKIV-4, MKIV-8 and BQIII still need their own manual.

Otari form OA-321C, © 1991, four pages for the Model 5050 two-, four- and eight-channel recorders: the “MX-5050 Series Configurations” table and a specification grid across the MKIV-2, MKIV-2E, MKIV-4, MKIV-8, BQIII, BIII-F, BIII-2 and BIII-2E. Its accessory list gives model qualifiers for some parts but leaves others at series level. A note on the grid gives the B-III and MARK IV-2 three speeds in switch-selectable 15/7½ or 7½/3¾ ips pairs, with the lower pair optional on the BQ-III, MARK IV-4 and MARK IV-8.

Pages 17–20 of worldradiohistory.com's Otari catalog bundle.

A service tech's binder — hand-labelled "lots of info, parts etc, various model Otari tape machines" — mixing Otari workshop training slides (bias, equalization, flux levels, balanced lines, servo control) with factory cross-reference lists for heads, pinch rollers, remotes, VU meters and connectors across the whole product line.

The MX-5050 appears throughout the reference lists: pinch roller part numbers (a previous owner highlighted exactly those rows), the "old MX-5050 series" VU meter and lamp numbers, and the CB-102 remote. 58-page scan, 1.5 MB.

One page headed “Important Information”, dated June 1989, on lubricating the direct-drive capstan motor. It applies to “MX-5050*, MX-70, MX-80, MTR-10/12, MTR-20, BTR-5 and BTR-10” — “*Except early MX-5050 which has belt drive capstan motor” — so it is not for the silver-face Mini Pro, whose capstan is belt driven. The oil is Anderol 456, Otari part PZ9E003, and “No other oil should be used.”

The MX-5050's motor has a foam ring round the top of its brass bearing: take off the dust cap and add one or two drops, after about 1,000 hours or every six months, and never on the part of the shaft the tape touches. Otari included the oil with every machine shipped after July 1, 1987. The page comes from a later printing of the BII instruction manual — its contact page carries Otari's Foster City address, so 1989 or after — that circulates without its title page, which is why only the bulletin is here.

Two-page excerpt from a 460-page period distributor catalog: its cover and original page 252, which lists Otari MX-5050 machines and accessories. The listing includes CB-102, FC-2B, RK-2B and ZA-52L with model or family wording. These are distributor claims, not an Otari factory compatibility chart; the model-specific factory sheets remain the stronger source for exact fits.

Mirrored from WorldRadioHistory with the scanned pages intact. The provenance link opens the complete catalog at the original Otari page.