help with tape travel adjustment

F

fgonza2

New member
Hi, i am in the process of adjusting my MS16 and i can see how the tape fluctuates slightly up and down on the heads and right side guide. Not enough to get off the guides or rub them hard, but as i look closer the tape wobbles up and down causing amplitude variations on the audio signal. I've tested it with the calibration tape. I have a rerubbered pinch roller from Terry. Any ideas what could be wrong ? could it be that the pinch roller is wobbly ? even if it has jsut been rerubbered ? when i press the pinch roller hard (to increase pressure) the issue seems to go away of be reduced. Both the pinch roller pressure and tape tension have been adjusted as per the manual.

Will appreciate any help, hoping someone with more knowledge will chine in.

Thanks,

Felipe
 
Poor Zenith alignment, AKA tilt of the head can cause the tape to skew and ride up and down the head. Head tilt is how straight up and down the head is against the tape. If the bottom or top of the head is tilted more forward it can cause what you are experiencing.

A common sign of the zenith being off is if either the top or the bottom part of the head has a wider wear pattern. If the bottom has the wider wear pattern, either the bottom part of the head is tilted too far forward or the top is tilted too far back. Same thing if the top part of the head has the wider wear pattern.

The attached image shows an exaggerated Zenith misalignment for illustration. As you can see the top of the head is tilted too far forward. In the real world it will be a more subtle tilt issue.

Sorry, I meant to answer this earlier, but lost track of the thread. I knew I was forgetting something.

Hope that helps

Zenith.jpg
 
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thanks for the guidance Beck. I removed the headstack to rule out this and effectively the tape movement is still there in the same amount. Already changes pinch roller and counter roller. both put through a lathe to make them round perfect. I opened another thread called "MS16 capstan azimuth" as i thought it was that. I am suspecting the cpastan bearings now, due to noise and some wobbling that i see from the shaft as i move it by hand slowly. Here's a link to the pictures of all the restoration that i've done on this machine so far... hopefully i'm done one day

https://picasaweb.google.com/104155...authkey=Gv1sRgCL7j1vW7mJ-ZvwE&feat=directlink
 
good luck resolving this fgonza2, hope it's not as tricky as it sounds. I had a similar issue that I was in fact able to fix by adjusting the capstan zenith (required shimming one or two of the bolts--it's described in the manual).
 
sorry misread your question.
The tape was riding up the last guide prior to the capstan/pinch roller.
 
ethyrvalve said:
sorry misread your question.
The tape was riding up the last guide prior to the capstan/pinch roller.
Click to expand...

Yeah, i had that problem too. Shimming helped on that. But the "up and down" movement i was unable to cure with that. It was causing amplitude changes as i could see the tape moving. Tomorrow i'll get the new capstan bearings and i can post some pictures of the process.
 
Hey it sounds like you're on the right path.
Out of curiosity, were you able to adjust the tension to spec with only the trimpots? The takeup tension was far too low in mine and I had to adjust the spring it get it in the correct range. A friend's MS-16 also needed the spring adjusted on the takeup side.
 
ethyrvalve said:
Hey it sounds like you're on the right path.
Out of curiosity, were you able to adjust the tension to spec with only the trimpots? The takeup tension was far too low in mine and I had to adjust the spring it get it in the correct range. A friend's MS-16 also needed the spring adjusted on the takeup side.
Click to expand...

I was without using the springs. The only tension that i was unable to adjust was the supply reel tension on rewind. I can get it to ~230g. The manual calls for 300g. On that particular case the tension springs have no effect as they are not involved. I am surprised that the tension is this high on this machine, i am wondering if the manual is correct. On my 1/2" the tension runs ~80g (TSR-8).
 
You're right, the specified tension does feel awful tight compared to my other 1" machine (Otari MX-70). I'd never considered that it could be an error.
Pure speculation: maybe they spec'd it that high because the motors are fairly weak (my biggest complaint with a machine that's in most respects very well designed IMO) and they wanted to avoid windshield wiper-ing on high frequencies at the beginning or end of a reel?
 
how do you compare the MX70 vs the MS16. I know the Otari is superior in almost everyway, but would like to hear your opinion
 
Sonically it's tough to do a fair comparison, my MX70 is a one-inch 8-track.
I've got to say that the Tascam has been a true workhorse while the Otari required new relays (the unsealed relays were corroded and created this weird, well documented, 'space ghost noise') and expensive proprietary FET ICs (I had early revisions that were prone to crackling when hot). Once the problem areas of the Otari were fixed it's been a very reliable excellent sounding machine.
Otari pros: easily switchable between speed pairs (you can configure it to be 7.5/15 or 15/30 ips); much more powerful motors; ability to switch between synch and repro on individual tracks (I like this for tape flanging); easier access to alignment pots; it seems to be slightly gentler on tape; better punch in/out (the MS-16 is very slow to punch out--I have had to get people to play from the punch in to the end of the song)
Tascam pros: built-in noise reduction (not my cup of tea); cheaper, more plentiful parts; smaller and much lighter (my brother and I almost killed ourselves moving the MX70 down a flight of stairs); LED readout for varispeed (I find this to be an amazingly useful feature!)
I'd be curious to hear the 16 track version of the MX70 myself.
Talldog on this forum has had both 16 tracks, maybe he'll chime in.
 
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