Yamaha MT8-X Problem

[koroviev]

Hi everyone, I bought a second-hand Yamaha MT8-X in uncertain condition, and received it today. I have some experience with analog multitrackers, but I am starting to believe this unit isn't functional . The problem is that as soon as I power it on, the capstan begins to spin. As far as I can tell, this isn't normal, but I am not sure. The manual states that I should only use Chromeposition tape, but I wanted to try playing, rewind etc. with a tape I had laying around which turned out to be the wrong type of tape. This resulted in the machine eating the tape. I realized in time and managed to get it all out. I tried playing some audio through the mixer, and this part seems to work. Now my questions is: is it normal that the capstan begins spinning when I turn it on, and if yes, is the reason it is eating my tapes that they are the wrong type? I thought perhaps it's due to the different magnetic properties, but maybe that's just wishful thinking.
Here is a video who has the same capstan problem, but with more noise and a completely non-functional machine: [edit: I can't post links yet because this is my first post, but you can find the video by searching for "Broken mt8x April 15"]

I greatly appreciate any help or advice!

 

[mdainsd]

I cannot speak directly to your machine, but a couple basic comments:

In most machines the capstan is on when ever power is on. The thought behind that being that you dont want to have the capstan try to come up to speed on pressing play or record, so its always ready. Some reel to reels use the tape loaded sensor to control the capstan on/off. No tape, no capstan motion.

What do you know about the condition of the tapes you are experimenting with? "Wrong type" should not cause tape eating.

And finally, Is the machine clean? I mean tape path in this case. Dirty tape paths can contribute to tape eating.

Also can you check that the take up side is actually spinning when play, rec or FF is selected? It might be as simple as selecting those functions with no cassette in the machine and observing through the window.

 

[koroviev]

Hi mdainsd! Thanks for your reply! The tapes I tried were still new and in packaging, so I assume that wouldn't be an issue. Regarding the take up side spinning, I was able to rewind the tape a bit, and while the machine was eating the tape, the tape did seem to be spinning at a normal place. That would only leave dirty tape paths, I will look into this and see if it helps.

 

[famous beagle]

Yes, the heads and tape path should be cleaned religiously anyway, so I'd recommend doing that before you try playing anymore tapes. There's no danger of using normal tapes in the machine; you just won't get nearly as good fidelity as you will with chrome ones. However, it's best to use 60 minute tapes or shorter, as longer ones (90 or 120) tend to stretch and can possibly break.

Unless you get some head cleaner, the best thing to use for cleaning heads is 99% isopropyl alcohol, like this:

Swan - M314 - Isopropyl Alcohol, 99% 16 oz. Plastic Bottle - 1 Each

 

[A Reel Person]

Hardware problem.

Agreed, if the capstan spins full time when the unit is on, is very likely normal. Porta units differ a little on this, but I'd not worry about it.

If it's eating tapes, is usually a hardware problem. The internal mechanism for this is usually a single idler roller that moves back and forth to turn either the right spindle (Play/FF) or the left spindle (RW). What usually happens is the rubber on this "tire" (as they're called), will deteriorate and stick to the motor or either side, thus making the tape mechanism inoperable. Try testing the FF or RW by itself, before Play & risking eating more tapes.

Search this forum for "246 Refurbishment" for a picture of the guts of a typical mechanism and the part I'm referring to, as well as what to do about it if you're mechanically inclined.

Solution 2: seek return and refund from the seller for inoperable device.

 

[koroviev]

Thanks for the suggestions, everyone! Tomorrow I will work on cleaning the tape path and heads, investigate a little more, and report back. Sadly, I bought the machine 'as is', as the seller claimed not to be able to test it. I didn't spend very much on it though, so if it turns out to be unfixable, I could probably still sell it for parts and not lose too much.

 

[mdainsd]

dont give up yet, LOL. Most of this stuff can be fixed.

 

[famous beagle]

Thanks for the suggestions, everyone! Tomorrow I will work on cleaning the tape path and heads, investigate a little more, and report back. Sadly, I bought the machine 'as is', as the seller claimed not to be able to test it. I didn't spend very much on it though, so if it turns out to be unfixable, I could probably still sell it for parts and not lose too much.

Yeah, I've pretty much learned that any of these things on an ebay listing:

1) It worked the last time I used it, but I have not been able to test it since, so...
2) I was told that it works perfectly, but I haven't been able to test it, so ...
3) It should work, but due to its age, it's being sold as-is with no returns

All pretty much guarantee that you're not going to get a functioning unit. But like Mdainsd said, the good news is that most of these 4-track problems can be fixed.

 

[koroviev]

Hi! I cleaned the tape heads, and started messing around a bit more, and I think there is a problem with the right sprocket (take-up?), I am not sure what it is called, but it is the thing that turns the right wheel of the tape. When I put in a tape and press play, only the left one turns, and this causes the tape to go all over the place. When I try to fast forward and rewind, the right sprocket turns for a second, but the left sprocket will only turn when there is a tape there. When I fast-forward or rewind the right sprocket makes a whirring sound that sounds a little too loud to be normal. It just turns for a second or two then stops. Perhaps the machine stops if it doesn't detect a tape? Any suggestions as to what could be causing this? Thanks again! Don't worry I'm not giving up!

 

[mdainsd]

Rubber parts. Either rubber wheels or belts as A REEL PERSON suggested. Again, I dont know that particular machine, but is there access through the bottom of it in the area or the tape transport?

 

[A Reel Person]

...

You're headed for a pretty serious teardown to replace the belt and idler tires. Sometimes the FF/RW might be driven by a belt, it varies by transport design in different units, but you have to disassemble it to fix it properly. This is pretty common with units of this age. I've done this repair a number of times on various Tascams. You'll have to be careful to mark or keep track of where connectors and plugs mate up, as well as many screws and some small parts that may have to come off to get to the problem area. F/I, on a Tascam 244/246 you must remove the bottom cover & take the unit apart, (424mkII/III separate it in halves), dismount the cassette mechanism entirely from the chassis and then disassemble the smaller components of the tape mech, itself,... then put it all back together again the way it came out!

There are a couple good threads here on 244/246 disassembly and repair, which might help. I've never done it on a Yamaha or the more modern Tascams, but many cassette mechanisms share similar designs.

Good luck.


[244 pics below]...

 

[koroviev]

It seems I managed to fix the problem! As per your suggestions I completely opened the machine and checked all the rubber parts. They seemed to be fine, so I cleaned all the components I had access to. After this, the sprockets still didn't seem to be turning the way the should be and I realized the problem was with the switching sprocket which distributes the turning power (in the red rectangle in the picture), it seemed to be unable to move from one sprocket to the other sometimes. After messing around for a while, I randomly loosened the screw to the top left of it (in the green rectangle) and it was able to move again! Apparently, it had become too tight for the small sprocket to switch from one side to the other.



I really appreciate all the help and suggestions you guys provided, and I promise to name my first-born (song) after you guys!

 

[famous beagle]

Awesome, glad to hear you got it up and running again! Good luck! Another one sheds the dust!

 

[A Reel Person]

That's Awesome!

Your post might benefit from a bigger blow up of the photo, but after DL the photo and zooming in, it looks like the more modern MT8X has the clutch assembly mating to the motor with a rubber tire & on the top side driving the L/R spindles with a gear.

If the rubber components are good, that's the best news. The part that swings back & forth is the "clutch". You're lucky you didn't shear off those teeth on the gear with this malfunction, which would be worst case.

I'm glad it was easy and not too serious. If loosening the mounting screw helped, it might be a good idea to apply a very tiny drop of light machine oil, but if what you did works, that's best overall!

 

[mdainsd]

Good! There is a certain satisfaction that comes from opening something up and getting it to work, isnt there?