[Troubleshooting] - Issues with an Otari MX-5050 BII-2...

[rerunmedia]

IB:

A good suggestion, and thanks very much-- but after reading up on the issue, it appears the main symptom of such a problem is a failure of the idler wheel to fully engage or disengage the capstan, leading to speed fluctuations or other difficulties.  I actually don't have any problems in that area right now-- when the machine is operative, the capstan and the wheel interact just fine, with crisp engagement and disengagement when the transport buttons are pushed, and no speed or pitch fluctuations during playback.

Overall, I think Jeri really hit the nail on the head-- though I confess I'm still trying to figure out how to remove and (possibly repair) that microswitch.  I've taken out all three of the visible screws that were holding it in place, and the thing just won't budge from its mounting!  And from the side angle I have to use, I can't see any way to get any Caig inside of it...

Thanks again for your thoughtful idea, though...!

- Kevin

[steveidosound]

Sometimes the actual button actuator on the switch is not well sealed and could be your access point for cleaner.
BTW, can you depress it directly and see if it is sticky? Is there a metal lever mounted to the switch that pushes it down?
Or does some external part of the recorder mechanism tied to the tension arm bear on the button actuator directly?

[rerunmedia]

That's the problem-- the switch contacts appear to be inside of a sealed unit.  When the tension arm is in the "resting" position, there's a small swinging armature inside the tape machine that makes contact with a corner of the microswitch case.  I'm guessing this causes the internal switch contacts inside to be pushed into an OFF position, which causes the circuit to the tape transport buttons to be defeated.  (That's why I now tend to think of this switch as a "kill" switch...)

When the tension arm is swung into "PLAY" position, that interior armature comes off the corner of the microswitch case, and the contacts inside are then free to move in the opposite direction, which activates the circuit to the tape transport buttons.  Now, in a new (or at least better-functioning) microswitch, the contacts move in and out of position quite readily... but on my machine, it appears that the interior of the switch has either become dirty inside, or otherwise degraded to the point that the contacts take a L-O-O-O-NG time to internally move in and out of position, once the arm is moved.

So unfortunately, as far as I can see, there is no real "button", per se-- only a raised bump that is the contact point on the case of the microswitch, and no other openings that I can see while it's mounted in place.  That's why I was hoping to be able to remove it, to give the entire case a closer look.

So if anyone has actually removed or replaced this switch on one of their machines, I'd love to hear about the process...

- Kevin

[rerunmedia]

Well, the microswitch finally came out-- it was mounted to the panel with some rather stubborn tape, which finally came loose with a bit of prying...

And what looked like a raised bump on the corner is actually a small pressure switch that goes in and out of the casing...  in the tension arm's "resting" position, the interior armature depresses that small pressure switch.  When the tension arm is moved into the "play" position, the interior armature is lifted off the pressure switch, which should allow the switch to pop right back up out of the casing.

Mine was sluggish, and even stuck a bit in the depressed position, as I clicked it up and down.

Time for some Caig, to see if we can make it work a little more readily..!

- Kevin

[jeri]

Good work!  I came across a recent ebay auction for a top panel showing most everything removed.  I thought the seller might have some insight on how to remove the switch -- but no need for that now!

You might be interested in contacting the seller to see if he still has the switch available if you wind up needing a replacement switch.  The auction is at:

  http://cgi.ebay.com/OTARI-MX5050-MX-5050-FRONT-PANEL-GOOD-SHAPE-/310308406044

Here is the photo of the back of the panel in case it is useful.  You can see the area where the adhesive tape must have held the switch.  A picture is worth a thousand words.  I wonder why Otari taped it in place since they also fastened it with screws.

[rerunmedia]

Success!!

I gave the push button part of the micro switch a good blast of Caig, and that seemed to do the trick-- it pops up and down much more readily now, and when mounted back into position, the movement of the tension arm now activates the capstan motor and transport buttons, just as it should... in other words, the 2-track is now beautifully functional!!

I wouldn't be surprised if that switch needed another shot in the future-- the switch probably sat in the depressed position for **years**, while the deck was inactive-- but it's nice to know exactly what the problem was!

Thanks again to everyone, and especially to you, Jeri, for the brainstorm.

Now to clean up this girl a little bit more...  :^)

- Kevin

(And that's a good question about the interior tape mounting for the microswitch... must have been an issue at some point, because in terms of looks, it **is** rather inelegant... certainly does hold the switch in place, though!)

[ironbut]

Fantastic Kevin!

Sometimes all the advice in the world can't help unless someone's willing to have a little patience and persistence.
So,.. good for you!

[steveidosound]

Success!!

I gave the push button part of the micro switch a good blast of Caig, and that seemed to do the trick-- it pops up and down much more readily now, and when mounted back into position, the movement of the tension arm now activates the capstan motor and transport buttons, just as it should... in other words, the 2-track is now beautifully functional!!

I wouldn't be surprised if that switch needed another shot in the future-- the switch probably sat in the depressed position for **years**, while the deck was inactive-- but it's nice to know exactly what the problem was!

Thanks again to everyone, and especially to you, Jeri, for the brainstorm.

Now to clean up this girl a little bit more...  :^)

- Kevin

(And that's a good question about the interior tape mounting for the microswitch... must have been an issue at some point, because in terms of looks, it **is** rather inelegant... certainly does hold the switch in place, though!)

Good! That is what I was trying to communicate when I was talking about the button actuator  on the switch being a point into which you could spray contact cleaner.
It is odd they would use a normally on switch (push to open) that stays depressed with no tape threaded rather than having it work the other way with a normally open switch which closes when the tension arm is up and a tape is threaded.

[crunch]

"Bring out your dead!!!"

Reviving an old thread, as I too am having issues with an Otari MX-5050 BII-2.

Things were going swimmingly until last night when we were to mixing to the deck in repro, the level on the left channel dropped by 10-15db.. When just sending signal to it, it's fine, levels are correct, but all the sudden, the left channel, and now the right channel are much lower than they should be. I would say the left is approx 15db down and the right is 10db or so. Any ideas on where to start? Previously recorded tapes still playback fine, but since we are monitoring off of what is there on tape, obviously the tape is hosed as well.

Can anyone point me into the right area to start looking?

[crunch]

Ugh! I figured it out. At first we thought it might be the record relays, but when in doubt, occam's razor comes into play; it turned out that the record level adjustment screws just needed exercising. Thank God!!!! Anyways, tada!

[ironbut]

Hey Crunch (btw, we use our real names here),

Glad to hear it was such an easy fix!
If you don't already have one, it would be a good idea to buy a test tape.
That way you will have a standard against which you can do adjustments.

http://home.comcast.net/~mrltapes/

Also, if you don't already have them, the 5050 service manuals can be downloaded.
http://www.tapeproject.com/smf/index.php/topic,396.15.html
(post #19)

[jacklmurr27]

Hey all, brand new here.

Recently acquired a pair of MX5050bii's and noticed that they're acting differently.  One of them seems to play and record fine, with need of some usual cleaning and calibration.  The other machine however, powers on but with the red record light flashing incessantly.  Furthermore, none of the REF FLUX or EQUALIZATION lights come on and when you press the RECORD, SEL - REP, or SRL buttons the lights dont turn on.  In addition, the machine doesn't keep speed right and the output seems low.  Anyone have any ideas why this may be? A bit of a newbie when it comes to R2R machines, but I'm learning as I go. 

Thanks so much

[ajmich]

This thread may be dead, but thought I'd offer some input -- some newly manufactured parts (including pinch rollers, tension arms, capstan oil) can be had from Athan Corp at http://www.athan.com/cgi-local/store.cgi?cat1=1003 ... they also sell on eBay.  I've got a roller & oil on order, hoping they're worth the cost!  Cheers...  Alex