otari mx5050MKIII-4

  • Thread starter Thread starter FALKEN
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If I might with my 2 cents worth...First, the wavering levels. Have you taken a good look at your capstan shaft? Is it clean, and is it excessively worn smooth? If it is, no matter how great the pinch roller is, you will never get the 'bite' to get the tape consistently thru the head nest. My ReVox has a capstan shaft that has a very tactile feel to it when new, like very very fine sandpaper. As it ages, the feel of it is different-it is smoother and shinier meaning it must be resurfaced since the tape is now slipping between the capstan/pinch roller interface. Popping sounds could be relays, or it may be as simple as the cables you prepared. Try switching them around with something else. Last, what I find puzzling most is the statement "the heads look new but the lifters are worn". How can that be? My point is your heads may not be as good as you think. That's all I have. Back to you.
 
FALKEN said:
oh man;

i've been trying to track this down. I've been working with a really good tape and what has happened is it started out sounding perfect. I had chalked it up to bad tape. After playing through and rewinding a few times, I have come to notice that the pops are coming from where I had pressed transport functions. basically, there are a lot of clicks and pops in the first song from hitting stop on the rewind back to zero. Would cleaning the relays solve this perhaps? what do they look like? ??
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If the pops are related to when a transport button has been pressed I'd suspect aging caps in the power supply section that feeds them juice. Re-capping them couldn't hurt and might just solve that particular issue. Sticky braking solenoids might also be drawing more current to actuate and also a possible suspect in regard to over stressing their power supply.

Cheers! :)
 
Thanks for the info guys. well, I can't directly link the pops and clicks to the transport functions, but there is a very high concentration towards the beginning of the tape, which led me in that direction. are the relays on the channel cards or closer to the transport controls? or are they on the mainboard? what part of them do you clean?
 
Cleaning relays should be done by removing the outer housing caps and cleaning the actual contact points with fine emery paper to sand the oxide off the contacts. The alternate method is to spray them with some Deoxit which may not work depending on the degree of corrosion. Better still, just desolder and replace them with new ones, if available.

Cheers! :)
 
so....how do I get these things open?
 

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here are a couple of pictures of what appear to be the psu caps?
 

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here is the 2nd one.
 

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It would be really cool if someone could look at these photos and tell me

-how to get inside those relays to clean them. do you just pull the top off? also do I need to clean all the white ones or just the clear ones?

-if the PSU caps look like they need replacing.

I have a new tape to mix and I would love to be able to do it without destroying it. :eek: :eek: :confused:
 
FALKEN said:
-do I need to clean all the white ones or just the clear ones?
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those look like sealed type. you can clean the dust off 'em though :)
FALKEN said:
-if the PSU caps look like they need replacing.
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no they don't look like it. Also that does not 100% mean that they are perfect. If there's no symptoms that may lead you to suspecting bad caps, then I personally would not worry about it. Some "technicians" may tell you that replacing electrolytic caps is a matter of when, not whether. Would that mean that you need to replace all the cups? The answer is - no (imo, of course).
FALKEN said:
-how to get inside those relays to clean them. do you just pull the top off?
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I have never done this myself, so don't know, but my guess is that the clear cups are "snapped on" flexable (and also breakable! :mad: ) hooks on the base.
see pic:
 

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Dr ZEE said:
no they don't look like it. Also that does not 100% mean that they are perfect. If there's no symptoms that may lead you to suspecting bad caps, then I personally would not worry about it. Some "technicians" may tell you that replacing electrolytic caps is a matter of when, not whether. Would that mean that you need to replace all the cups? The answer is - no (imo, of course).
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thanks for taking the time out to try to help me, mike. I finally got a weekend off so I was going to try to fix this thing in-between watching the gators take the SEC and slamming some beers. :p

The only symptoms are that there seem to be some pops and clicks appearing on the tape (which seem to be corellated with the pushing of transport functions) and a bit more hiss than one would expect (might be the use of too much compression though). Any more thoughts would be great. I've never re-capped anything but I am thinking it would solve the issues. And messing with the relays is how a fellow board-member lost his otari entirely so I would really like to get this right. This would really be a sweet, sweet machine if I could. :)
 
FALKEN said:
I would really like to get this right. :)
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Yeah. well. heh heh, - to get this right. I personally can't guide you here. I am a "get in, search and destroy" type of "technician". so.
If I was you, I'd clean the relays contacts. Test the machine. See if popping problem go away. The system is freaking complex electronically. To do it 100% right you'd need to study through it. Do you want to do it? Do you have time to do it? If not, then your choices are: don't do it or take your chances and accept it if you screw up. Of course there is always an option to bring the machine to the service center and then hope that who ever is going to fix it is at least slightly more capable to it than you are :p
good luck
 
You can't tell by looking if a cap is bad, unless of course it's bulging, burnt or leaking. They can look new and still be open.

The relays with the plastic covers are the only ones you can clean, but likely the only ones that need attention -- most commonly.

It's hard to say what the pops and noises are from. Caps are a good bet, but probably not the ones in the PS section. When they fail you will know it... lights out.

I don't know this machine very well but I would suspect caps in the transport control section if the noises occur while operating those buttons.

Tim
:)
 
Dr ZEE said:
Do you want to do it? Do you have time to do it?
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Yes, yes, I just don't know HOW to do it. I know its a story told more often but there aren't really any techs where I live. Besides, I think I could do it, given the proper direction. I know I could replace the caps, I just wish I knew which ones to do and if there was a way to test them? (And what to replace them with...radio shack stock? order something online?) As far as the relay "contacts", do you mean to just clean the solder points on the board? or to open those things up? thanks again...
 
man I just can't seem to get these suckers open...... :confused:
 
FALKEN said:
man I just can't seem to get these suckers open...... :confused:
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Relay cases can be tricky to open.

Some have soldered down metal tops and others have clear plastic tops that can snapped off but most will crack when you try to pry them open. It's usually a little easier to pop them open if you desolder them from the board and then can get at them from a better angle to pop off the case.

Even once you get them open, you may find them so delicate and miniature in their internal workings that replacing them is usually the only workable route.

Cheers! :)
 
well the contacts are very clear, I think I would be able to clean them ok, if I could just get the thing off. I guess I'll just keep trying....
 
i've found some boring to the toothache data, that you may find readable here's the page: http://relays.tycoelectronics.com/appnotes/ , there some links to pdfs, click on each and see if any info there for you to digest.
also this doc: http://relays.tycoelectronics.com/appnotes/app_pdfs/13c3265.pdf
Reading that crap isn't going to help you to fix your machine, it's just for some geral edu/info.
Now, if you are planing on doing some soldering work there, replacing caps or what ever. Have you done this kind of work before? Sorry, I don't remember if you mentioned in the past. If you have not, then practice on something first. Good thing to get some disfunc PCB with some componets on it and practice desoldering removing various components (without destroing them and not buring them to death). Get desoldering gun: I use one of radioshack's ten-bucksers THIS ONE. I assume you already have regular soldering gun and stuff. You really need to practice to do this, no big deal at all, but still.
good luck doing all that.
sit still, relax, it'll be quick:
:D :D :D
 

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Thanks, Zee.

I have done some of this kind of work before, though I am still a novice. I have done countless guitar wirings, and cables, and also made a small 8-channel passive mixer, which although not technically difficult, did require a few small pcb's and a lot of soldering points. I don't have a gun though, although I should probably get one anyway.

I've been messing with those relays and still can't get them open!!! I think if I could clean the relays (and switches) if everything weren't fixed, I may as well replace the relays and then the caps in that order. I have never done a cap job though but I guess I have never needed to! But I think it would be the logical next-step of learning this stuff.
 
hey if i were to go to rat shack to get the solder gun do you think they would have all the caps I would need as well? the values are all there I just don't know what "kind" they are. most of them are small and navy blue/light blue. then there are some larger ones of those color and then some big ones that are black with grey lettering. ?
 
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