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Otari MX-5050 III-b trimpot broken - thoughts?

 
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JohnRichard
audio school


Joined: 11 Feb 2014
Posts: 7
Location: Lexington, KY

PostPosted: Sat Nov 19, 2016 5:36 pm    Post subject: Otari MX-5050 III-b trimpot broken - thoughts? Reply with quote

Dear Members,

Recently I was working on my MX-5050 which is at about %60 now. While I was performing the routine alignment, V207 came apart on me. It's an open frame carbon trimpot, but I dont know what the voltage/rating is so I am hesitant to rip the amp section apart to put a new one in.

Secondly, someone is selling a complete amp section for $150. The bad part about my unit is that some previous owner hardwired the deck and the amp together.

Everything seems functional at this point, however this trimpot is causing a channel dropout on record. Playback is not effected.

I mention the amp being sold as it may be in better condition than my current machine, but I would either need to buy the appropriate connectors and cables to make it work, or hard wire it back in to the existing setup.

at this point I am wondering which solution is better in the long run - restoring the machine (if I can find those obscure cable connectors at all) to factory specifications, or continue with the hardwired amp and try to replace the pots.


Thoughts?
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Drone
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Joined: 18 Dec 2009
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Location: Uranus

PostPosted: Sun Nov 20, 2016 10:03 am    Post subject: Re: Otari MX-5050 III-b trimpot broken - thoughts? Reply with quote

I'm going to imagine that a trimpot has no great voltage thru it, if you know the value and scale (log, antilog, linear), I'd just replace it. If you are worried about finessing, Bourns do some nice quality multi-turn pots that give all the finesse you could need. Very Happy
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floid
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Joined: 03 Jan 2006
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PostPosted: Sun Nov 20, 2016 4:20 pm    Post subject: Re: Otari MX-5050 III-b trimpot broken - thoughts? Reply with quote

A spare amp would be nice to have, just like having a spare transmission for an older vehicle you're committed to maintaining. But a trimpot is on the order of a speedometer cable or similar, not enough to justify total replacement... unless you have to pull the whole thing either way. Then the math changes from difference in cost of parts plus labor to difference in cost of parts and anticipated time until you have to do the same labor again. You mention "ripping the amp section apart, " does that imply it's gonna be a serious undertaking just to get to the trimpot? Virtually the same as pulling the entire amp?
The service manual probably has a parts list with the proper spec. And even a top of the line multi-turn Bourns shouldn't (quite Shocked ) cost $150. Just make sure you're getting something of similar size and footprint.
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JohnRichard
audio school


Joined: 11 Feb 2014
Posts: 7
Location: Lexington, KY

PostPosted: Mon Nov 21, 2016 9:20 am    Post subject: Re: Otari MX-5050 III-b trimpot broken - thoughts? Reply with quote

It is in a precarious spot to get to. It's also soldered onto the bottom so I would have to take a lot of the amp apart.

That said, it should never need replacing after the fact.

I agree a spare amp would be lovely. I'll have to see if I can find the correct specifications in one of the manuals. It doesn't do much, but it does stop record signal from getting to the head - which is not so good?

I'll get a trimpot and set to take the thing apart.
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Drone
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Location: Uranus

PostPosted: Mon Nov 21, 2016 10:02 am    Post subject: Re: Otari MX-5050 III-b trimpot broken - thoughts? Reply with quote

Depending on how bad it is to remove, you don't technically need access to the bottom of the board to get the part out, if it's already disintegrated, snip away what you can of the pot, leaving the legs protruding, apply heat to the leg with your iron, and you can hopefully remove it with tweezers.

Putting the new part it, can be a lot trickier, you basically either need a part with exposed legs and use a pair of clamps or pliers to divert heat from the part as you solder the leg, or you have to jury rig a little harness. I think bourns do stand-up pots that might work here.



It's finicky work, but perhaps in this case easier than the board removal?
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