Otari MTR-90 Reel Tension Servo Adjustments

[Matt C]

I'm in the middle of checking through the transport on my recently acquired MTR-90 (it's a mkiii if that makes any difference), and I've got a quick question.  When fine tuning the reel tension servo, the manual says to make an adjustment "if there is any slippage of the tape on the capstan roller" (I'm looking at section 6.1.9.5 in the Transport Alignment section on the manual). 

My question - how do I recognize this slippage? Is it obvious or subtle? 

 

[Tubetec]

Hi ,
I used use and do the basic servicing on the Mtr-90 back in the studio I used work in years ago ,over time a residue tends to build up on the capstan ,it gets shiny and looses grip ,then your tape counter wont keep time and you probably notice sloppy tape handling by the machine. Regular cleaning  will help prevent this ,Isopropyl and a lint free cloth is what I used for capstan, it can take a bit of work to clean it if its been sitting along time or allowed to build up. Another sign that shows up problems in the tape path is take up arm flutter while the machine speeds up or slows down in fast forward or rewind mode. The other one was what we used term 'hunting' type behaviour  when useing the auto locate to find a particular place on the tape. Easiest way to check is thread up a tape ,fast forward in about 30 seconds or a minute ,this will be the space you use for you test tones ,set the clock to zero,make a small chinagraph mark on the back of the tape right by say the record head,now fast forward almost to the end of the spool ,hit stop and return to zero ,your reference mark should line up perfectly again ,if not you have tape slip.

 

[gyraf]

My question - how do I recognize this slippage? Is it obvious or subtle?

Thread tape, pencil mark a spot on tape, reset counter, wind to other end of tape, locate at 0, and see how far from the pencilmark you are.

On a MK2, locating without TC, I always considered +/-25-30cm alright (~distance from repro head to the two rollers)

Jakob E.

 

[Matt C]

Thanks guys, I'll run some tests.

A related question - are the original rollers on MTR-90s black/dark in color?  I'm trying to figure out if my rollers are original or were replaced at some point.  Their color looks similar to the Athan rollers (sort of light yellow I guess), but I haven't been able to confirm. 

I'm tuning up these transport functions partly to help me figure out if the rollers are performing okay or if they should be replaced. The transport doesn't seem to be having any major issues and the rollers don't show any obviously visible deformations, but I'm new to this machine so I'm not quite sure what to expect performance-wise.

 

[Winetree]

The original rollers were a brownish color. They should feel soft and slightly grippy. Not hard.
Looking at the rollers, you shouldn't see any shinny glaze. This will cause slippage.

 

[Tubetec]

Id second what Winetree said , light brown ,matt finish , if there turned dark they could be caked in residue from the back of the tape .

 

[Matt C]

I'm gonna try to get in touch with the maintenance guy who looked after this machine at it's previous home, he should be able to shed some light on this and other questions.

to clarify, my rollers haven't turned black with gunk, they look this this:

 

[Tubetec]

Looks like the colour and maybe the material used by otari for the rollers may differ from model to model,looks like the yellowish is normal for the Mk III.