Yamaha MT8X Plays Super Fast Only

R

Rick N. Backer

New member
Hi all (again)!

The problem with my MT8X is that is plays really fast - as if I’m fast forwarding the tape. I can slow it down only by a hair using the pitch shift with the “Vari”/“Fix” button pushed in (green light on). I use Audacity to record it and then I have to slow the speed down by -158.

It started doing this out of nowhere. I had it under the bed, brought it out, dusty as heck, put a tape in and that’s when I noticed it. It sat for 4 years, but I never had a single problem with it.

What could the problem be?

[Edit 1: I forgot to mention - The capstan is constantly spinning. From the moment I power it up it goes non-stop.]

[EDIT 2: NOW the capstan isn't turning at all and the unit won't play a tape.]

Thanks guys!
 
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Yah it could be the tape isn’t engaging the capstan shaft due to a bad pinch roller or control belt isn’t fully actuating the headblock assembly to the tape and the tape to the capstan. If it used to work, has been sitting and now doesn’t, first thing I usually do is replace all the rubber parts.
 
sweetbeats said:
Yah it could be the tape isn’t engaging the capstan shaft due to a bad pinch roller or control belt isn’t fully actuating the headblock assembly to the tape and the tape to the capstan. If it used to work, has been sitting and now doesn’t, first thing I usually do is replace all the rubber parts.
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I forgot to mention! The capstan is constantly spinning from the moment I power it up. I've never seen this before with any of my multitrack recorders.

Does that mean it is something else or does this confirm it's a problem with the pinch roller or control belt?

FYI. I was cleaning the heads and capstan. The roller next to the capstan was rolling along with just fine with the capstan.

[UPDATE: NOW THE CAPSTAN DOESN'T TURN AT ALL AND THE UNIT ISN'T ABLE TO PLAY A SINGLE TAPE]

Thank you both!
 
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It can “roll along just fine”, but if the roller is hardened or slick or if the mechanism isn’t able to apply the correct pressure, the takeup tension can pull the tape through the capstan rather than the capstan being able to regulate the tape speed as designed.

It’s about 50/50 as to the capstan spinning all the time. Sometimes a machine is designed that way, other times it doesn’t spin up until tape is loaded.
 
sweetbeats said:
It can “roll along just fine”, but if the roller is hardened or slick or if the mechanism isn’t able to apply the correct pressure, the takeup tension can pull the tape through the capstan rather than the capstan being able to regulate the tape speed as designed.

It’s about 50/50 as to the capstan spinning all the time. Sometimes a machine is designed that way, other times it doesn’t spin up until tape is loaded.
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Thanks again. I guess you didn't see my update. Now the capstan is no longer spinning and the unit doesn't play tapes at all anymore.
I press "Play" and nothing. :cry:
 
If there is a capstan belt, and it was failing, it may have broken or fallen off. Or if it was getting sticky it may have stretched and bound up the motor. Can you hear a motor spinning and it’s just that the capstan shaft isn’t spinning?
 
sweetbeats said:
If it used to work, has been sitting and now doesn’t, first thing I usually do is replace all the rubber parts.
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Here’s your answer. ^^^^^
Every rubber part is suspect. I’d change it all. Even if some rubber is ‘still good’, it’s the same age as the failed rubber. It WILL fail soon.
 
RFR said:
Here’s your answer. ^^^^^
Every rubber part is suspect. I’d change it all. Even if some rubber is ‘still good’, it’s the same age as the failed rubber. It WILL fail soon.
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100% I agree with this. There is no machine from this era that still has good rubber parts unless they have been replaced.
 
sweetbeats said:
If there is a capstan belt, and it was failing, it may have broken or fallen off. Or if it was getting sticky it may have stretched and bound up the motor. Can you hear a motor spinning and it’s just that the capstan shaft isn’t spinning?
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No, I can't hear the motor. The capstan and the pinch roller are not spinning.

Great, do you mean the motor may need to be replaced??? 😥

I'll be opening it up after I open and check out my MT120 which is not getting any sound with the switch in the "Stereo" position, but gets some very faint sound in the "Monitor" position. I will make a separate thread for that. I'm more familiar with the MT120s. I've been using them since 1994/95 and have done work on them.

I just hope I don't need a new MT8X motor. I found someone on Reverb that has all the belts and rubber replacement parts. So I'm already going to be spending almost $90 on the belts, pinch roller and tire belt for both the MT8X and the MT4X. Although I'm having trouble finding a tire belt for the MT8X. If I need a new motor on top of that I will be screwed.

I really appreciate all the responses and advice. My old and newer cassette recordings and multitrack machine mean the world to me. I want to be able to fix any problems so I can keep them up and running. I want to digitize all of my old recordings from 34 years ago to present day. And I want to keep record on them. I'm way more of an analog musician and sound guy over all. I only use the computer when I absolutely have to.

BTW, Where do you guys get your replacement parts? So far I'm only finding parts on Reverb and eBay. Very little on eBay.

Thanks again guys!
 
I understand the capstan shaft is not spinning. If the belt is broken or fallen off the motor will spin but the capstan shaft will not. The motor is very quiet when it spins.

I can’t jump to a conclusion your motor has failed. I did not say it has failed nor am I suggesting it has failed. I’m telling you you need to open it up and investigate. As I said previously, the belt could be broken, the belt could have fatigued, stretched and fallen off, or the belt could have turned to goo and jammed up the motor. Just open it and look.

And regarding the parts, you’ve asked where to get parts a couple of times, like where the best place is to get parts. There is no one-stop-shop for this stuff and that’s what I’m trying to help you understand…I guess the answer to the question where do we get parts is: wherever you can get the parts. It all depends on the make and model and vintage of the machine, how obscure or popular it was and is, what part you’re looking for, etc. I always include reaching out to the manufacturer on my list of places to check, because in some cases they still have certain parts in stock, AND have the best price. Because people on the open market like to gouge. And sometimes the part with the premium price is also conversely inferior. There is, almost without exception, no substitute for a factory genuine part unless there is an improved part (like Athan’s pinch rollers), or the factory parts are all NOS and we’re talking about rubber. Old rubber is…old rubber. So don’t be shy to reach out to Yamaha and ask. I’m less confident that Yamaha has anything for any of the MT cassette machines than say Tascam has for their cassette machines, but it doesn’t hurt to find out. You only have to do that one time and then you know whether it’s a resource or a dry well there. Earlier this year, while I was struggling to find a replacement reel table drive tire for my Tascam 238…super frustrating experience there…I realized I’d forgotten my own advice…called Tascam and to my surprise they had stock of recent manufacture, for very cheap. Done. Outside of that, when I’m looking for a part I start with a web search, which will include eBay and Reverb offerings in the results as well as others if the exist, sometimes Amazon has stuff…found some stuff at Full Compass one time…I also try the search by make, model and the part name (for instance Tascam 244 capstan belt) or the general part term like “belt”, “tire”, “roller” (Tascam 244 belt), AND a separate search by the part number from the service manual. I found something practically impossible to find once when I searched by the part number…just the number…in Japan. Yes the shipping was not cheap, but I got the part I needed. So there’s my part search tips and tricks for you. I find Reverb prices are more inflated. There are a couple sellers on eBay that have reasonable prices and good quality parts. I had a bad experience with West Coast Belts. Maybe it was isolated…but it was a bad experience.
 
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