Otari 5050MII Speed Problem

[rbouch8828]

My Otari 5050BII only runs on the "slow" speeds.  That is if the switch in back is set to low, the switch in front only works at 3 3/4, if the switch in back is set to high, the switch in front only works on 7 1/2.  I have removed and tested the switch for the front panel and it checks out as working properly.  Does anyone have any suggestions as to where I should look next?

Roland

[ironbut]

Hi Roland,
Welcome to the forum.

Do you have a manual for your Otari? You can download one here;

http://www.analogrules.com/

There's an internal adjustment you need to make to enable 15ips. Once it's changed, the front panel switch will go between 7 1/2 and 15 ips.

[rbouch8828]

Hello Steve,

Yes, I have the manual and the schematics.  I know about the high/low switch in the back. The problem is that the capstan stops turning when you select the higher speed with the button on the front panel.  It doesn't matter which way the rear switch is set.  I removed and tested the front panel switch and it tests OK.  Whenever I switch it to the higher speed the capstan shuts down.

Roland

[ironbut]

Oops, sorry Roland. I should have read your post a little more closely.

You should check the connections that lead to that switch. It could be an oxidized contact on one of the multipin connectors that connects the power supply or control board to that switch. It's a pretty good idea to pull out and then plug in all those connectors one at a time (just be careful since some circuit boards can get brittle with age). Patience is very important when you're trying to troubleshoot this kinda stuff. Do one thing at a time and check to see if it helped (sometimes doing this without actually cleaning the pins can make something else stop working).
BTW Do you know anything about how the machine was used and if it was stored for a while?

[rbouch8828]

Hello Steve,

Thanks for the suggestions.  I will try them and hopefully that will do the trick.  I am traveling right now, so it will have to wait until I return home.

I bought this deck on E-bay, so I don't know about its history prior to my receiving it.  It was damaged in shipping tome and I had to weld the frame, which had broken.  Everything else was fine.  It is a very clean unit, so it appears that it had been cared for.  I have a second deck that a friend gave me for parts.  It was used in my friend's radio station, so it is pretty beat up, but many of the parts are still quite useable.

Thanks again for the tips.

Roland

[ironbut]

If the deck got whacked that badly, you should check to be sure the circuit boards are seated correctly. The capstan servo/control board for instance has edge pin connectors and it may have gotten crooked or even cracked on impact. Also, since the frame had to be welded, you should take a look at the boards to be sure there isn't any little pieces of metal bypassing any components. Maybe take some compressed air and blow off the the ones on top (Be careful with duster "cans" since they can spray the liquid propellant onto components and turn them into "super conductors" by cooling them. If you do spew some onto a board, give it at least an hour before you turn it on. Don't ask me how I know that!).

[rbouch8828]

Steve,

Thanks for all the good tips.  I will check the edge connectors and I will blow off the boards.  When I disassembled it to remove the frame, I did disconnect all the boards and I removed them from the chassis.  I had taken off all the exterior panels as well.  It could be that during the re-assembly, something was not seated properly, or got loosened.

Roland

[joeljoel1947]

If its like many Otari's with the same issue you have (I had two myself) then the issue, believe it or not, is your pitch control switch in the middle of the deck.  Some de-oxit spray will do the trick.  On one of mine, I was able to fix it just by rotaing the knob and pulling itout and in a few dozen times (bad contact).

[rbouch8828]

Is it possible for the pitch control to affect only the higher speed?

[joeljoel1947]

Yes.  Everything runs through that pitch switch.  If no high speeds, or no low speeds, work on any given switch setting WITHIN THE OTARI (either your 3 3/4 and 7 1/2 ips won't work or your 7 1/2 and 15 ips won't work, or NONE might work as well, save for 1 speed no matter where its set) then you can bet its your pitch switch!)  See here:

http://www.tapeheads.net/showthread.php?t=5597

[rbouch8828]

Thank you for that tip.  I will try it tomorrow.

[joeljoel1947]

You're welcome.  Let us know how it turns out.

[ironbut]

Nice one Joel!
I had some speed stability problems on a Technics and I cleaned the speed selector switch. While I was in that general area, I went ahead and cleaned all the surrounding switches/pots and one of them was the pitch control. I always assumed the "fix" was because of cleaning the selector but it could've been the pitch switch that did it.
Just goes to show ya, if you're cleaning switches and pots, do em all while you're at it.

[rbouch8828]

I have tried Deox on the Pitch control and I have tried cycling the pot and the switch, but that has not helped.  As long as I have the front panel "High/Low" switch in the "High" position, the capstan doesn't turn.  I have noticed that I can hear the faint click of a relay from time to time and when that relay clicks the capstan moves very slightly.

[joeljoel1947]

Can you "jumpstart" the capstan by turning it with your hand when in the high position and get it to begin turning?