Otari MX5050 BIII-2 Adventures

It is very well built and heavy. Boards swing out for easy service. One of the improvements over the BII, the BIII uses standard NAB hub adapters. It was in bagged isolation for near 9 months. There were some ugly spiders seen in the vents upon arrival. The PA spiders looked badder than my basement spiders. Upon reviewing pics I spotted another one above and between the heads.

I removed capstan motor to service the pinch roller and tape lifter linkage. The lifters were sticking. All Nichicon caps including some Gold.

"The Otari BIII upgrades over the BII primarily in the tape transport, which features a smarter, logic-based control system for smoother and quieter tape handling, and includes soft-touch buttons instead of the BII's electromechanical ones. Other improvements include a Parallel I/O interface, locking spindles, and improved NAB large reel clamps."








Balanced in and out.

I'm amazed how clean it is inside. Just some single spider webs here and there. While on it's back, remove bottom cover and two face panel screws and lower board pulls out and folds down. Some narrows strips of rolled paper towels were placed alongside switches to catch DeOxit that runs out. After application and a soak, they are repeatedly actuated. Then I used canned air to blow them out. There were small square holes to dribble DeOxit in.

I removed the potentiometers for a more limited, controlled application of DeOxit F5 fader. I didn't want to wash any grease out of the shafts.

I removed the narrow control panel for a controlled DeOxit application to the switches.

I have some Otari spec capstan oil ordered. Some say oil is oil, Otari techs tell me to get the real deal. The direct drive capstan motor has a rear ball bearing while the drive end has a bushing.

I did a variac power up, all looks good. Just did some basic play, FF, Fast Rewind. I have no two track tapes and I don't want to test record until I get the capstan oil.






Just the four push buttons on left that stick out were cleaned. The speed encoder was sealed.

Still await the capstan oil but the VU meter bulbs arrived. OEM are frosted. Frosted are scarce and when found, sellers typically ask ~$15 to $25 each. I purchased five inexpensive clear for $14 shipped. Too cold outside for etching chemicals so I sanded them a bit to reduce the glare.

Otari did pin 3 hot on the XLR and had a notice silkscreened next to them. I was mulling my options as most gear these days is pin 2 hot. Thanks to Ken for pointing me to the AES14-1992 standard which is pin 2 hot or positive, pin 3 cold or negative. Made it easy to decide what to do.

Standard XLR to RCA adapters that I have would ground pin 3 to 1, the shield. Instead of making custom adapters/cables to connect pin 3 to center pin RCA, I swapped wires on pin 2 and 3 for output, input and mic XLR's. Big font on a label under them makes it obvious.

Aaron had a week off and said pick a day go to the tree farm to make some nice side panels for the Otari MX-5050. It’s a long day at ~1:30 to Aaron and then another hour to the farm plus working the rough-cut wood.

Everyone seems to do dark wood for Otari sides so we chose some Cherry along with some nice Walnut. The chunk of Cherry I brought back to make matching footers didn’t make it through the planer so that's on the to do list. The Walnut sides are still in stages of finishing.





This deck came with rack mounts and had no footers. They sell reproduction plastic footers on ebay. I’ve seen 3D printed and ones machined from Delrin. Cost ~ $60 to $70. Some offer wood footers which look a bit nicer. These were made to exact length of 8.66 though I chose to make them a bit thicker (15/16”) than original. This deck weighs 62 pounds and the last thing you want is setting it down with your fingers under the side panels with thin footers.



Mount screws were countersunk and I installed metal washers to keep the narrower screw head from burrowing into the footer.



Plenty of screw thread engagement in base of deck.



The original footers were extended past the front of deck as it is front heavy. I’ve seen guys just have round footers on the bottom, but one accidental bump can send it falling on its face.




Instead of the original Allen head screws and cone cup washers (which are plastic) I chose some nicer looking aluminum shoulder washers and flat head M4 black stainless screws for a nicer finished look. I have some Allen head on the way to replace the Phillips head.




So long to the "firewood sides" as Aaron called them before I did some half fast repairs. They were purchased while the deck was in bagged isolation and were slightly smaller and not for a MX-5050 as advertised, but I drilled holes to make them fit. They were much better for carrying the deck around than the metal rack mounts. I opted for no carry handles in any of the new wood sides.