capstan of Otari MX 5050 mk III-8

[8trackfan]

I have a question about the capstan on my MX 5050. The capstan appears worn and shiny where it is in the tape path and rough at both ends. I believe I read a post on this forum that said the capstan shaft should have a slightly rough surface and that if it was shiny it needs to be replaced. Is this true? Also, does anyone know where (besides the manufacturer) locally you can get a felt ring that goes around the capstan. Also the manual calls for the capstan to be lubricated with Anderol oil #456. I have no idea where locally you get that kind of oil. I have searched the internet and only found it availble in bulk. Is there some place to get just a small bottle, or is there another lubricant that I can use instead? I must say that I have only a little experience with reel to reel tape machines and I am excited about getting this one up and running. However, I need to calibrate the machine and I am willing to buy some calibration tape. I have seen several post that suggest MRL for this and I have been to their site, but do to my inexperience I am not quite sure what kind of test tape I need. I would hate to cough up that much money and get the wrong kind. Can anyone help. Your comments and advice are much appreciated.

--G

 

[ECC82]

G,
In the '60s through late '70s, I used to repair, rebuild and upgrade R to R machines for the local studios. Ampex (and most other) direct drive capstan motors had stainless steel shafts, fully polished, always shiny. You did not want rough touching the backing on pro decks or the oxide on consumer decks (pinch roller on backing side, very bad). The friction of a good condition pinch roller against the capstan with properly set tension will regulate the movement of the tape through the pinch. Newer machines bypassed the costly process of a fully polished shaft and the result is slightly rough top and bottom, shiny at the path like Otari. As long as your tape backing is not idling against the spinning capstan 24 hours a day, you should not have to worry about replacing it. Make sure your pinch roller is not rock hard. It needs to have some "give". The felt ring should last the life of the machine. If you have to replace it, the felt is sized, buy it from Otari. You can substitute TS-619 Sewing Machine Oil. It is crystal clear synthetic oil for the textile industry. Same characteristics as Anderol oil 456. Try T. S. Moly Lubricants, Inc. The one I use is pocket pen size, with a needle and cap. If you're using 15 IPS buy the MRL 12.5 mm ½" Open Reel 8 minutes 380 mm/s 15 in/s 3_J___ $220 list (ouch!). That test tape will only help you calibrate the playback. In order to do a complete calibration you will need an oscilloscope and calibrated audio generator to make sure the REC side is correct. Maintaining analog yourself requires a small investment in tools or you pay a tech or service center. I hope that helps you.

 

[Beck]

I have a question about the capstan on my MX 5050. The capstan appears worn and shiny where it is in the tape path and rough at both ends. I believe I read a post on this forum that said the capstan shaft should have a slightly rough surface and that if it was shiny it needs to be replaced. Is this true?

You don’t necessarily need to replace it, but the capstan should not have a mirror finish on the Otari MX5050. It will cause slippage, which does more damage to tape than a rougher surface.

Often this slick area is just the outer most surface and is partly tape residue that won’t come off with alcohol and cotton swabs. It has a burnished look. You can restore the desired dull finish with careful use of a piece of 3M Scotch-Brite scour pad. With the capstan turning, it takes but a few seconds to restore a uniform surface along the length of the capstan.

You should cover the machine except the area right around the capstan and put masking tape on the top panel around the base of the capstan so residue won’t fall down around it. Use a mini-vac attachment and compressed air to clean up.

Don’t try this with steel wool or sandpaper. Scotch-Brite is aluminum oxide and nylon, so it won’t change surface dimensions. It will only remove the shiny area that q-tips and cleaner can’t.

Yeah, the MRL tapes are nearly out of reach for many of us. The one you want that will do it all is MRL 31J229. You can also find new-old-stock or lightly used on ebay sometimes; MRL and other calibration tapes. Below is a list ones that will work with any ½” 8-track @ 15 ips IEC equalization.

MRL 31J229
TEAC YTT-1144
TEAC YTT-1144-2
Fostex 9200
BASF 337534A

 

[8trackfan]

Thanks for the Info

I just wanted to say thanks for the help. I am getting close to officially getting the machine up and running.

--G