We put together this handy checklist for ourselves and others who align our MM-1200 transport tensions infrequently enough that we refer to the manuals to remind us of all the steps. Even ignoring the diagrams, that involves 4 pages of text, including jumping back and forth between the Constant Tension manual and the Operation and Maintenance manual.Warning: It is very heavily abbbreviated, so it’s only for folks who have done it before!
- 27V and 15V power supplies should be accurate ± 0.5V.
- Check the tension arm for your chosen tape width ( 2” marker=8oz; 1” marker=4oz).
- Put transport card on the extender.
- Set pots R1 thru R8, and R10, fully counter clockwise. Set pots R14, R15 and R34 to mid position. Note: all except R34 are 4-turn devices.
- With no tape on machine, secure end of tape arm as if tape present.
- Press FF, and adjust supply gain R7 until no motion.
- Press RW, and adjust takeup gain R8 until no motion.
- Mount tape, and spool until equal amount on each reel.
- Engage lift defeat while in Stop mode, and adjust R3 for tension between supply reel and LH roller guide of 6.5oz (2”) or 3.5oz (1”), ± 0.5oz.
Similarly R6 for the same tensions between RH roller guide and takeup reel.
Adjust R34 if necessary to reduce transport oscillation (but then resume at point 6).
Note: it’s ok to set lower tensions if easier tape handling/editing desired.
- Thread tape across front of capstan (so pinch wheel doesn’t drive it). Enter Play mode while holding takeup reel, and adjust R2 for tension arm on 2” mark, or R10 for tension arm on 1” mark, according to tape mounted. Thread tape normally again.
- Press RW with two-thirds of tape on supply reel, allow shuttle speed to stabilize, then adjust R4 for tension arm at 2” mark (or short of it if faster wind preferred).
- Press FF with two-thirds of tape on takeup reel, allow shuttle speed to stabilize, then adjust R1 for tension arm at 2” mark (or short of it if faster wind preferred).
- While still in FF, check TP1 on Constant Tension PWA for 27V ± 5%.
- Press Play with Tentelometer close to takeup reel. For 2” tape adjust R60 (upper pot on Constant Tension PWA) for 13oz within 1oz. For 1” tape adjust R61 (lower pot) for 6.5oz within 1 oz..
Spot-check that tension stays the same within 2oz from start to finish of the largest reel to be used.
…and finally, a personal tip. If you use both 1” and 2” tape on your machine, do 1” first. Doing it the other way round you may end up with the servo gain (R34) set too low to get adequate tensions for 1”.