Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Analogue Source Turntables, Tonearms, Cartridges, Phono Stages, Tuners, Tape Recorders, etc.

So you think you want to play with tape: An Otari Story
So you think you want to play with tape: An Otari Story
Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 14th May 2019, 01:04 AM   #1
kevinkr is offline kevinkr  United States
diyAudio Moderator
 
kevinkr's Avatar
 
Join Date: Sep 2004
Location: Boston, Massachusetts
So you think you want to play with tape: An Otari Story
Default So you think you want to play with tape: An Otari Story

A few months ago one of my best friends decided I needed a new audio affliction™ and gave the first of my current two OTARI tape recorders.

Today I am the proud owner of two ancient Otari's;

A 1983 vintage MX-5050BII-2 which arrived here sometime in late January if memory serves.

And in late March I came home from the Montreal hifi show after a detour to the deep woods of NH with a rather challenged example of a 1984 vintage MX-5050MKIII-2 with its cart. This is a bridge style recorder which is a dream to work on by virtue of the cart. I don't recommend buying one without as the form factor is otherwise brutally awkward to deal with.

Neither of these decks were in running condition when I got them..

This then is the story of one fool's mission to save them from the scrap heap.

The machines now both run, record and sound surprisingly decent recording test dubs from a digital source here.

The whole point in the long term is put together a couple of good, and not too expensive machines to play those hideously expensive commercial tapes on.
Attached Images
File Type: jpg MX5050BII-2.JPG (755.3 KB, 682 views)
File Type: jpg MX5050MKIII-2.JPG (970.7 KB, 677 views)
__________________
"To argue with a person who has renounced the use of reason is like administering medicine to the dead." - Thomas Paine
  Reply With Quote
Old 14th May 2019, 01:14 AM   #2
tom31415926 is offline tom31415926  United States
diyAudio Member
 
Join Date: Dec 2006
In the 1980's I worked at a studio that had two MX5050s. It was my job to align them, replace heads (we used them a lot), and generally make sure they were meeting spec. I also maintained Ampex 350s, Ampex 440s, and even an old MR70 (huge!).

The 5050s did a great job on location recording, and were a go-to machine for voice-over original recordings (we did a lot of radio spots). I recall they had a switchable playback head, usually used for 1/4 track playback. We used the 440s for in-studio high-quality mastering.

It was a lot of fun working there (while a grad student in EE). Glad to see someone using them. Good job getting them running! I hope you can get tape!

Tom

Last edited by tom31415926; 14th May 2019 at 01:15 AM. Reason: forgot to complement OP on getting them working
  Reply With Quote
Old 14th May 2019, 01:33 AM   #3
kevinkr is offline kevinkr  United States
diyAudio Moderator
 
kevinkr's Avatar
 
Join Date: Sep 2004
Location: Boston, Massachusetts
So you think you want to play with tape: An Otari Story
There are a fair number of myths circulating about the Otari decks. My observations should apply generally to models other than the two referenced in the opening post.

Each successive generation has improvements in the electronics.

BII, MKIII, and BIII series machines are similar with the BIII being the most evolved. The BIII is the first series to use improved switches in the transport, they also tend to be somewhat more expensive than the older models.

Surprisingly dead machines are often not too hard to bring back to life if you are patient and can use a scope and do basic trouble-shooting, should that not be the case I recommend you not consider buying a non-functional deck as they are quite complex.

Things to look at are the condition of the heads, guides and pinch roller. Probably a good idea to avoid machines with bad heads - they will be expensive to replace.

Heads that are worn to the depth of 1 mil (the thickness of the tape generally used) or so can generally be relapped at considerable expense by an outfit like JRF.

Replacing the heads on the head block is possible for a skilled diy'er, but doing a good alignment probably isn't.

My BII had some corrosion damage due to the foam pad on the back panel that disintegrated into a corrosive goo. This resulted in an open trace that cause some very odd problems preventing the capstan from engaging.

The MKIII had some bad switches and a capstan motor that liked to seize up.

One of the myths circulating about these machines surrounds the Nichicon capacitors used in these machines not ever needing to be replaced. Otari was extremely conservative and they almost never fail, but that does not mean that they are still doing the job effectively.

After a recap (provided you don't break something in the process) the machine will run and sound better.
Attached Images
File Type: jpg Resr_view_r.jpg (233.6 KB, 706 views)
File Type: jpg Board_r.jpg (241.0 KB, 679 views)
File Type: jpg before.JPG (842.6 KB, 640 views)
File Type: jpg done1.jpg (206.7 KB, 241 views)
File Type: jpg done2.JPG (809.5 KB, 242 views)
__________________
"To argue with a person who has renounced the use of reason is like administering medicine to the dead." - Thomas Paine
  Reply With Quote
Old 14th May 2019, 02:11 AM   #4
kevinkr is offline kevinkr  United States
diyAudio Moderator
 
kevinkr's Avatar
 
Join Date: Sep 2004
Location: Boston, Massachusetts
So you think you want to play with tape: An Otari Story
Default Capstan Motors

Before lubricating the capstan motor bearing you need to remove the bearing dust cap, to do so remove the pinch roller, noting location of all washers as you remove it.

Make sure the well is clean before adding lubricant, any accumulated debris in there due to neglect and lack of service will get washed down into the bearing and likely cause the motor to seize.

Use only the proper lubricant which is Anderol 431 or the Athan branded equivalent. These machines have an oilite bearing.

The capstan motors in these decks are often neglected, but very easy to remove and disassemble. This applies only to the later servo capstan motor decks. I've not worked on an older deck with the AC motor and belt drive.

You need to remove the pinch roller, and may at worst have to remove the head cover, and the rear trim piece if you cannot remove the capstan dust cap. If you can actually remove it you only need to remove the pinch roller.

In a BII you must remove the screws that retain the logic board to the rear frame rails and move it out of the way.

In a MKIII you will need to remove a bunch of screws and carefully remove the front trim and move the logic board out of the way.

There are 4 screws that secure the servo PCB, there is a tie wrap to one of the frame rails that you will need to cut (carefully) and 4 screws that secure the motor to the chassis that you need to remove. The whole assembly then lifts out.

See illustration shamelessly lifted from one of the many scans of Otari service manuals on line.

There are 3 screws that retain the motor to the mounting plate - I remove them and the plate.

There will be a tie wrap or two snug up against the body of the motor, carefully snip this and remove. Failure to remove tie wrap could result in an expensive mistake as you attempt to separate the motor halves.

There are 3 screws that secure the case halves, remove these and pull straight up.

Check that the 3 sensor coils in the top half have remained in place. (If broken Athan can repair) Secure them with a dab of high viscosity superglue on the bottom if necessary. (I took pictures but cannot find them.

Clean the bearing bore in the top half of the housing. Polish the shaft if there is an scoring with very fine sand paper (320 grit) until any sharp edges are removed.

Clean everything!

Apply a small amount of the anderol and reassemble. Add a couple of drops in the well.
Reinstall. Should run quietly and maintain speed.
Attached Images
File Type: jpg Capstan motor.JPG (62.3 KB, 241 views)
File Type: jpg electronics compartment.JPG (604.0 KB, 173 views)
__________________
"To argue with a person who has renounced the use of reason is like administering medicine to the dead." - Thomas Paine
  Reply With Quote
Old 14th May 2019, 02:24 AM   #5
kevinkr is offline kevinkr  United States
diyAudio Moderator
 
kevinkr's Avatar
 
Join Date: Sep 2004
Location: Boston, Massachusetts
So you think you want to play with tape: An Otari Story
Quote:
Originally Posted by tom31415926 View Post
In the 1980's I worked at a studio that had two MX5050s. It was my job to align them, replace heads (we used them a lot), and generally make sure they were meeting spec. I also maintained Ampex 350s, Ampex 440s, and even an old MR70 (huge!).

The 5050s did a great job on location recording, and were a go-to machine for voice-over original recordings (we did a lot of radio spots). I recall they had a switchable playback head, usually used for 1/4 track playback. We used the 440s for in-studio high-quality mastering.

It was a lot of fun working there (while a grad student in EE). Glad to see someone using them. Good job getting them running! I hope you can get tape!

Tom
Thank You!

Tape is actually easy to get from a variety of sources. I use SM900 tape which is essentially the old BASF studio master series stuff now made by RecordingTheMasters - Professional Analog Audio Tapes

This is what I have calibrated my decks to use.

The other source is: ATR Magnetics

Demand seems high enough now to keep tape viable.

I currently own 3 head stacks, and a set of good relapped heads as well. The best stack has new SAKI heads on it now installed in the MKIII.

The next best stack will be relapped sometime in the next year, and I have a third stack with heads that could be relapped but will be replaced. I will send the stack to JRF as I am unlikely to be able to align it properly due to lack of experience and the tools required.

The MKIII is modified, and sounds quite nice, the BII-2 will get the same mods soon. Jumping the gun a bit, but here are a couple of shots of the MKIII. (looks rough, sounds really good)
Attached Images
File Type: jpg MKIII-2A.jpg (118.5 KB, 225 views)
File Type: jpg MKIII-2C.jpg (94.2 KB, 206 views)
File Type: jpg MKIII-2F.jpg (126.3 KB, 211 views)
File Type: jpg MKIII-2E.jpg (114.4 KB, 187 views)
__________________
"To argue with a person who has renounced the use of reason is like administering medicine to the dead." - Thomas Paine
  Reply With Quote
Old 16th May 2019, 02:32 AM   #6
kevinkr is offline kevinkr  United States
diyAudio Moderator
 
kevinkr's Avatar
 
Join Date: Sep 2004
Location: Boston, Massachusetts
So you think you want to play with tape: An Otari Story
Anyone out there? No fellow Otari owners? Just Crickets..
Last post unless someone is actually interested.
__________________
"To argue with a person who has renounced the use of reason is like administering medicine to the dead." - Thomas Paine
  Reply With Quote
Old 16th May 2019, 03:13 PM   #7
anatech is offline anatech  Canada
diyAudio Moderator
 
anatech's Avatar
 
Join Date: Jun 2004
Location: Georgetown, On
So you think you want to play with tape: An Otari Story
Hi Kevin,
CHRIP!

I think maybe you might want to discuss the tape head amplifier and line level circuit modifications. The electronics are of the early 80's and were not made to be extremely good, just good enough. With our parts today, and some of the circuitry we now use, those machines could be given a real boost in performance. Additionally, if you look at improved turntable EQ amps, they would easily adapt to a tape head application. The very low noise Salas phono preamp would drop the noise floor a lot and may possibly really wake that machine up.

From what I see there, the Otari was similar to some of the Tascam machines in build except no bridge. So electronic improvements to the Otari would also apply to the Tascam and maybe even Revox and Studer. That encompasses pretty much every member who is interested in tape.

Another cool idea for you. Look at the head amps in Nakamichi BX-300 or later machines. Nakamichi made some really low noise circuitry, and ripping off their designs might also be a giant step forward.

-Chris
__________________
"Just because you can, doesn't mean you should" © my Wife
  Reply With Quote
Old 16th May 2019, 03:20 PM   #8
Osvaldo de Banfield is offline Osvaldo de Banfield  Argentina
diyAudio Member
 
Osvaldo de Banfield's Avatar
 
Join Date: Dec 2011
Location: Barrio Garay,Almirante Brown, Buenos Aires, Argentina
They remember me the "datasette" of the C64 and the "Mission: impossible" series :-)
__________________
Osvaldo F. Zappacosta. Electronic Engineer UTN FRA from 2001.
Argentine Ham Radio LW1DSE since 1987.
  Reply With Quote
Old 16th May 2019, 04:01 PM   #9
Bigun is offline Bigun  Canada
diyAudio Member
 
Bigun's Avatar
 
Join Date: Jan 2009
Location: Waterloo, ON or Herefordshire UK
So you think you want to play with tape: An Otari Story
Quote:
Originally Posted by kevinkr View Post
A few months ago one of my best friends decided I needed a new audio affliction™
OMG, those things look scary to work on, large, very complicated, lots and lotsa wires, all sorts of i.c.'s., impossible to align mechanical bits and limited folk who can help. Are you sure your best friend is actually a friend ?
__________________
"The test of the machine is the satisfaction it gives you. There isn't any other test. If the machine produces tranquility it's right. If it disturbs you it's wrong until either the machine or your mind is changed." Robert M Pirsig.
  Reply With Quote
Old 16th May 2019, 04:50 PM   #10
anatech is offline anatech  Canada
diyAudio Moderator
 
anatech's Avatar
 
Join Date: Jun 2004
Location: Georgetown, On
So you think you want to play with tape: An Otari Story
Hi Gareth,
There are plenty of people out there to help. We were invisible because we worked in studios and radio stations. Places where the public never see.

These machines are easier to work with than consumer grade equipment. They were designed with service in mind for starters with less emphasis on marketing and more on performance. They are more satisfying to work on because the results are better when you're done than consumer equipment. In most cases the equipment is built heavier with fewer short cuts because they had to be able to run to high hours, then be repaired and do it all over again.

Once you hear something recorded live off one of these machines, you will marvel at the impact the music has. Even off a CD, comparing one of these to a cassette deck has a clear winner that is predictable. You would be shocked at how basic the audio electronics are with R-R decks, meanwhile all the stops were pulled out on cassette decks to make them listenable. If you put some effort into the electronics in a good open reel machine, you can attain pretty high levels of performance.

-Chris
__________________
"Just because you can, doesn't mean you should" © my Wife
  Reply With Quote

Reply


So you think you want to play with tape: An Otari StoryHide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Otari MX7000 Megaphon Analog Line Level 4 19th February 2019 04:45 AM
use of a tape recorder's play-head as a mic. dehmat Analogue Source 9 5th October 2016 03:11 PM
Otari MTR-15 tape alignment kamran Analogue Source 8 27th September 2011 03:18 PM
Otari MTR-10 Voltages marklang Analogue Source 14 9th April 2011 08:09 PM
How play tape through a computer CarlU Digital Source 1 27th August 2006 11:42 AM


New To Site? Need Help?

All times are GMT. The time now is 10:15 PM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 14.29%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Copyright ©1999-2019 diyAudio
Wiki