Tascam 22-2 Capstan Not Starting & Slowing Down

[samsteele]

Hi Everyone,
I'm brand new to this community as I just got my first reel to reel deck: a Tascam 22-2. I am an enigineer and am pretty good with electronics and mechanics, but I'm new to these systems so I am looking for some advice.

Initially the deck would only work in FF/RW and not Play/Rec. I opened up the unit and saw that the belt was completely disintegrated, so I purchased a new belt from ebay and installed the belt.

After installing the belt, I noticed that it seemed like the capstan motor was not strong enough to move the flywheel since it was still not moving. After trying play mode once or twice, I noticed the solenoids (for break and capstan) stopped working (previously they worked). At this point I checked the fuses with a multi-meter., and F505 and F503 were both out so I replaced those. The solenoids started working again and I started to see a sign of life from the capstan motor.

The capstan motor seems very weak though. Most of the time, it cannot start on its own when it's connected to the flywheel via the belt (no issue when it's not under load), but if I manually spin it to 'kick start' it, it seems to get up to speed. The high/low speed seem to be working as well. Using this kick start method I was able to get 1-2 seconds of recording until the motor slowed and stopped again.
Based on feedback from another thread here I tested the pinch roller tension and that didn't seem to help either. I also adjusted the clearance between the capstan shaft and plate in the unit per the manual. The motor and flywheel seem to spin freely manually, so it doesn't seemed like any bearings are binding.

So now I am thinking a couple of possible causes of a weak capstan motor:
1. The motor itself could be bad
2. The power supply to the motor is bad (could this be some capacitors that need to be replaced?)

Does anyone have other thoughts of what could be causing this? Any pointers on how to troubleshoot these possible causes? Should I probe the voltage going to the motor during playback to see if it's getting the right voltage?

Thanks in advance,

Sam

 

[skywaveTDR]

Ebay usually has the wrong part that they sell you. They are usually idiots there as they are deceptive in selling equipment there also. Now to the correct procedure- Firts you are best off consulting the PRB cross reference for belt size and type. I suspect it is around a 14.5" belt although I think I have used the PRN 14.85" belt with success. Not only doe sthe belt have to be changed but some oiling as well including the capstan bearing and top motor bearing under the pulley. I usually take the motor pulley off and that takes a 2mm hex wrench. A few drops in that upper bearing will help the motor a lot. What oil do I use in my shop for the last 4 years? Ams oil Signature series 0W30 synthetic motor oil. Why this? As I was trying to get rid of it I used it on a A2000R deck. A machine that has never seen numbers of wow and flutter below .06%. Well much to my surprise the wow and flutter measured .02% on this deck. I disconnected ans tested again and it consistently kept this value which had to be the oil. Since that time it is all that I use and great numbers are seen on decks like the BR20 at .0135% with that oil. So a good belt that is not too tight, oiling where it is needed like I do it- pull the capstan shaft OUT of the bearing and put oil in the bearing as there is a void in there, then oil shaft and work it back and forth. The other two things that happen is the washer rubber spacer between the flywheel and capstan bearing can decay and get frictional. This can have the same cleaned off washer but the rubber is replaced by a Oring and a nylon washer for friction reduction. The the flywheel is put on so that the front to back play is 1/16" or 2mm it is not a critical amount just that there is some play. I put Lubriplate grease at the end of capstan shaft that goes through the flywheel and meets with the thrust plate at the end. Lubriplate 105 will not dry up like the Japanese grease does. Some deck I see do not have the play required but are hard to turn and of course are adjusted wrong this way. Just so you know I worked at Teac Factory Service in Arlington Heights and was a Lead Technician there and have fixed decks for 47 years.

 

[skywaveTDR]

Motor wise a too hard to turn belt situation is the cause but if the motor is all carboned up the commutator might be shunting current away from the fields. I have taken motors apart many times to inspect brush life and to put AMSoil in the end bearing. The black carbon dust is blown out and the commutator surface polished to a smooth condition. These motor now sell for near $300 as there are no new ones but they can be fixed up if the brushes are still good. Brushes should be about 2mm tall - it they are paper thin then that motor does not have that much time left but as long as the fields are good a new brush might be installed. The thing is no one has offered or I have not found 3X3 X3mm brushes and so larger brushes can not be cut like some think as they will break apart. Next the old brush is removed off the copper springs and the clean up of the spring to accept the new brush piece. How are they joined? A materail called conductive epoxy that is expensive as it has silver in it MG used to sell it for about $40/ tube set. This is the ONLY way the brush can be attached as other conductive (LED) like glues will never handle the current. The silver stuff which was the original fastener material must be used. The gaps of the commutator should only have air in them NOT carbon which is the shunt. I use a trac two razor blade part to clean these out as it is thinner than 15/1000" thick stainless.

 

[samsteele]

Thank you for the reply! I saw some of your other posts on this forum related to the Teac devices so that inspired me to post, and I'm glad you replied. It does make sense that too tight of a belt and then lack of oil on the captsan bearing and motor bearings will cause these to not have the strength to turn the whole system. I am pretty familiar with motors, so I think I'll pull it apart and see what I find and also make sure it all has oil. Thanks for the specifics on oil type as well, I'll get to work!