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OTARI MX80 users unite!!
Old 17th November 2019
  #91
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dlmorley's Avatar
If anyone is selling an MX80 near Belgium, I'm looking..
Old 18th November 2019
  #92
Gear Addict
 

I'm not near Belgium, but I could be persuaded to sell my MX-80.

PM me.




Quote:
Originally Posted by dlmorley View Post
If anyone is selling an MX80 near Belgium, I'm looking..
Old 19th November 2019
  #93
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dlmorley's Avatar
Quote:
Originally Posted by wiz1der View Post
I'm not near Belgium, but I could be persuaded to sell my MX-80.

PM me.
Thanks!
Problem solved locally I think however..
Old 20th November 2019
  #94
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Brett 123's Avatar
 

I have one at the studio.

Am on the look out for a 16 track head if anyone has one to sell?

Thanks ,

Brett
Old 4th January 2020
  #95
Here for the gear
Hi freq eq adjustments not working

Anyone have any ideas when I went to align the machine today the high frequency eq trimpots at 10k didnt seem to move the needle much, and the needle was way low -10ish, same with the bias trimpots. I went through and double checked my card input/output adjustments and everything. The last time I used it, the eq pots worked fine though i have had issues like this with the bias adjustments before.

Using a brand new mrl tape and the deck is set up for the right ref flux and eq.

I have messed around with the audio control pcb before (the high/low input output switches and the +10db vu switch) but it makes the most sense for those to be at +4db and the +10db to be turned off respectively. I have a toft atb board, which the spec sheet says +4db nominal levels.

Is there anything I’m missing or is it possible there is an issue with the machine somewhere? Any help would be greatly appreciated. Thank you
Old 4th January 2020
  #96
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Also.... I maybe have broken a trimpot while troubleshooting this, thinking it was stuck, are those easily found? Still manufactured etc?
Old 4th January 2020
  #97
Gear Nut
 
Antony Scott's Avatar
Quote:
Originally Posted by archetypestudio View Post
I have messed around with the audio control pcb before (the high/low input output switches and the +10db vu switch) but it makes the most sense for those to be at +4db and the +10db to be turned off respectively. I have a toft atb board, which the spec sheet says +4db nominal levels.
Input and Output switches (sw5, sw4) must be on "Hi" position,
and VU switch (sw8) must be "Off" pos.


Quote:
Originally Posted by archetypestudio View Post
Anyone have any ideas when I went to align the machine today the high frequency eq trimpots at 10k didnt seem to move the needle much, and the needle was way low -10ish, same with the bias trimpots.
It happens on all 24 tracks?
And it happens when you align repro amps (during MRL playing)
or when you align the rec (durind record a test tone)?
Maybe it happens because the bias has not been set or not properly...

Quote:
Originally Posted by archetypestudio View Post
Also.... I maybe have broken a trimpot while troubleshooting this, thinking it was stuck, are those easily found? Still manufactured etc?
Geniune trimmers hardly available today :(
But you can put 1-2 pots from unused position (as example, unused speed).

I replaced a lot pots on the new cermet pots Murata...
Old 4th January 2020
  #98
Here for the gear
Quote:
Originally Posted by Antony Scott View Post
It happens on all 24 tracks?
And it happens when you align repro amps (during MRL playing)
or when you align the rec (durind record a test tone)?
Maybe it happens because the bias has not been set or not properly...
Thanks for the reply. It is only happening on the repro calibration, across all channels when I try to adjust the eq trimpots to 0db for 10k. The VU's are reading at -10db and barely move at all from -10db with full rotation across the trimpots. The same test tone applied to the input and sel/repro monitoring brings the needles to where they need to be at 0db.

Is there maybe something wrong with the repro head? I demagnetized it before starting calibration like I normally do, nothing out of the ordinary there. Other frequencies seem to be registering at their proper place.

I'm stumped. This has never happened with this machine before and I've owned and used it regularly for over two years now.
Old 5th January 2020
  #99
Gear Nut
 
Antony Scott's Avatar
Quote:
Originally Posted by archetypestudio View Post
Thanks for the reply. It is only happening on the repro calibration, across all channels when I try to adjust the eq trimpots to 0db for 10k. The VU's are reading at -10db and barely move at all from -10db with full rotation across the trimpots.
In fact, this is a strange defect.

Well, I have two thoughts...
First, maybe you rotate the wrong trimmers (for a another speed).
Try rotating pots (on any one track) for low and hi speed and observe whether the reading on VU will change while rotating one of them.
Typically, during the trimmer rotates, the VU readings should change more widely.
The effect of poor high-frequency reading on all tracks can also be that the head azimuth may not be adjusted correctly.

The second thought is that you have a MRL tape recorded with a -10 dB level of the 10 khz tone.
Could you write the number of your tape and its other parameters indicated on the sticker?
And at what speed, ref.level and EQ are you working on your MX-80?
Old 7th January 2020
  #100
Here for the gear
I figured it out! The screw for my azimuth adjustment on the repro head had a big burr in it that made it keep slipping out of perpendicular. Found a replacement screw at Ace Hardware and now I’m back in business!
Old 7th January 2020
  #101
Gear Nut
 
Antony Scott's Avatar
Congratulations, it's good that you found a problem!
Old 18th February 2020
  #102
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Thinking of selling a 16 track MX80 South East england PM for info
Old 3rd April 2020
  #103
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MX80 serial interface card schematic

Hello fellow MX80 owners,

As I see that there is some activity here, I'd like to add my two cents. First, those of you who have downloaded the
manual from Audio Rules, there is a schematic page missing. That is one of the two schematic pages for the MX80
remote interface card. If you go to my following webpage link you will find a scanned copy of that schematic page.
Also, I provide the PCB assembly artwork from that manual as a high resolution scan. I also provide a hex/binary image
of EPROM software from that card. It may be helpful to someone.

My webpage is: http://joehammer.us/Otari.htm

Enjoy,

Joe Hammer
Old 17th April 2020
  #104
Gear Nut
 
Antony Scott's Avatar
Quote:
Originally Posted by joe hammer View Post
Hello fellow MX80 owners ...
Hello Joe,

This will definitely be useful for some here (I also do not have a one page in the schematic of the remote card ).

Although the interface itself usually works fine, sometimes with some errors that may be cured by restarting the MX80 machine.

IMHO, for all MX80 owners, a more significant problem in the future is that the firmware of the EPROM in the remote control and on the remote card may be damaged over time, since such memory is usually not designed for storage for many decades.

You have copied the EPROM of card, and this is very good. If it were possible to copy the remote EPROM, it would be great.

Thanks for your help!

Last edited by Antony Scott; 18th April 2020 at 07:25 PM..
Old 19th April 2020
  #105
Here for the gear
 

MX80 remote S/W link

Hello Antony,

Nice to hear from you as some google searching lead me to here and I stumbled across you name.
I enjoy you postings. Per your request, I just uploaded to my webpage a copy of the MX remote EPROM image.
So, please fell free to download a copy.

I acquired my first MX80 just a few years ago and started hacking it. I realized that if the remote
stopped working, I would just have an overweight door stop. So I went on a quest to acquire a copy of the
serial communications protocol between the machine and its remote. I spoke with some folks who I felt
might be of assistance but they were not able to help. As a matter of fact, they asked for a copy if
I found one. Oh well, no help there.

So the big question is, how do I get a copy of that protocol? I could reverse engineer the firmware of
both the machine and remote or I could slap a serial communications protocol analyzer onto the serial cable
between the machine and remote. I don't have an analyzer and it would take a lot of time to reverse engineer
the firmware. So... What the heck, I started to reverse engineer the firmware in the serial card, I spend
quite a bit of time to do that and it's still not done. But, I did learn a hell of a lot about the serial
card operation and its kinda scary.

Ultimately I wrote some software to check the UART on the card as a loop around test, test the switches and
toggle the LED indicators on the card and that accounts for about maybe not quite a 1/2 of that cards
function. I was going to publish the executable (and maybe the source), but unless the individual using
the code really understands embedded systems, this code and it usage would be way over their head.
And if they understood that code, they could write it themselves. To publish the code, I would need to write
a small manual and I don't have the time. This stuff is not for amateurs... If resistor and capacitors are
difficult to understand for some people, embedded software and using it to troubleshoot is another universe
that even drugs won't help!

As this is a 8080/8085 base machine I found several software monitor source code builds that I modified
to operate on this serial card. Some of the monitors I liked and several I didn't. But they were helpful
for ideas to implement into my code. I am still thinking of some sort of home made serial communications
protocol analyzer as it is a combination of hardware and software. One way I was going to do an analyzer
is to use some of these "new" old CP/M systems as hardware with additional H/W as necessary to interface
to the serial cable. Think RC2014 Z80 systems.

Any way, I'm rambling on too much but keep in touch. I don't know deep your technical background is, but lets talk.

P.S., I do have a second MX80 in the garage and its in good condition. Hey the price was right and it was
only about 25 miles away from me.
Old 23rd April 2020
  #106
Here for the gear
 

Mx80 32/24

I’m new to the MX 80. This is a 32 track with a 24 headstack. Also have the 32 headstack that’s never been used.

Issue I need to resolve:

Tape plays about 5 minutes then starts to slow down then speed up. At a point it just stops 1/2 way through reel. Then transport starts to get stuck and will not engage FF or RW.

I cleaned the guides and rollers and issue is unresolved.

Any help appreciated.
Old 1st May 2020
  #107
Here for the gear
 

1. Stupid question. I assume you tried a different reel/manufacturers type of tape and you still have the same problem?
2. If so, check out the capstan and its associated electronics.

Remember how the tape moves, the capstan controls the speed of the tape. If you have a symmetrical amount of
tape on both reels and the capstan is not driving the tape, the reels will should stay still. Hence my recommendation
about the capstan and it electronics.

I have not had this problem but that is where I would start. I would monitor the voltage applied to the capstan motor
as a start and dig down from there!
Old 13th May 2020
  #108
Here for the gear
 

1. I don’t have another manufacturers reel to test yet.
2. I placed my fingernail against the top metal of the pinch roller and the issue resolved. Took fingernail off pinch roller top and the issue was back.

Maybe this just needs a new pinch roller.

Heads are out for a lap.
Old 25th May 2020
  #109
Here for the gear
 

Hi, it sounds like you have a plan and that's a good find. I would check the specs and adjustment procedure for the pinch roller assembly in the manual first before just replacing the pinch roller, unless it has deteriorated significantly. I would think the manual should have something about a pinch roller adjustment procedure!

Yours,

Joe Hammer
Old 27th May 2020
  #110
Here for the gear
 

Thanks Joe, I'll check the manual and figure this out.

I'm also looking for a 16 track head stack for this mx80, if anyone has a good one for sale.
Old 30th May 2020
  #111
Here for the gear
 

I share you desire to obtain a 16 track head stack as I have some old 16 track masters. But, I would be happy just to have a 16 track repro head mounted in a spare head stack with dummy heads in the other locations.
Old 3 weeks ago
  #112
Gear Maniac
 
Dan O's Avatar
 

Quote:
Originally Posted by Antony Scott View Post
Guys, I corrected the link to YouTube
(I completed the video on cleaning the switches on the remote, there are more details, and posted it) :
YouTube
Hi Antony! Thanks for your great video! It would have been great also with some pictures on how you disassembled the switches.

I'v recently bought a MX80 with cb140 remote. Some of the lever switches are very loose. Is it also possible to repair them?

and

Do you have any advice on how to loosen up sticky transport switches? Do you know if there are replacements available?

Thanks

( Btw. there is a great FB otari group which maybe you can also join if you're up to it. )
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