So I know that this is a common issue with semi pro machines, but all is well until I get halfway through my reel of tape. The tape slightly starts to slow down a little bit and doesn't play at a consistent speed. I don't think its sticky tape (no squealing and I've examined the tape, seems fine.) It basically only happens when theres about half the reel of tape left, thats when I notice it starts to slow a bit... Any thoughts?
4 Track Tape machine (Tascam 44) slows down while playing..Why?
- Thread starter racer
- Start date
jamesperrett
Active member
I'd stick with what you are using. I think people questioned the tape because quite a few people asking similar questions seem to be buying old Ampex tape on Ebay without realising that it has issues.
sweetbeats
Reel deep thoughts...
As already indicated:
1. Check for a dried out/loose capstan belt (if it is a belt-drive capstan...not sure if you have the early or late version 44...if it is the version that looks similar to the Model 42 or Model 48, your capstan is direct drive)
2. Check the condition of your pinch roller. Is it soft/rubbery/grippy or is it firm/dry/slick? If the latter, it won’t deform like it should when pressed against the capstan shaft. When the roller is of proper condition, when the tape is pinched between the roller and capstan shaft, the rubber roller deforms to the shape of the capstan shaft which wraps the tape around a small portion of the capstan shaft. This increases the surface contact between the shaft and tape allowing the shaft to drive the tape, which is it’s job. If the pinch roller is hard the contact area between the shaft and tape becomes insufficient and there can then exist slippage between the shaft and tape.
3. Check your pinch roller pressure. If the pinch roller pressure is too light, regardless of the condition of the roller, it won’t properly deform against the capstan shaft, and as per #2 above this increases the chance of slippage between the capstan shaft and tape.
I think, if I’m understanding your original post correctly, there may be some question of the tape being sticky because you indicated the transport performs fine initially but then the tape speed in PLAY decreases. This sounds like sticky tape. Do you hear any squealing sounds when the tape is slowing down? Are there any deposits/crud being left on the guides or heads?
1. Check for a dried out/loose capstan belt (if it is a belt-drive capstan...not sure if you have the early or late version 44...if it is the version that looks similar to the Model 42 or Model 48, your capstan is direct drive)
2. Check the condition of your pinch roller. Is it soft/rubbery/grippy or is it firm/dry/slick? If the latter, it won’t deform like it should when pressed against the capstan shaft. When the roller is of proper condition, when the tape is pinched between the roller and capstan shaft, the rubber roller deforms to the shape of the capstan shaft which wraps the tape around a small portion of the capstan shaft. This increases the surface contact between the shaft and tape allowing the shaft to drive the tape, which is it’s job. If the pinch roller is hard the contact area between the shaft and tape becomes insufficient and there can then exist slippage between the shaft and tape.
3. Check your pinch roller pressure. If the pinch roller pressure is too light, regardless of the condition of the roller, it won’t properly deform against the capstan shaft, and as per #2 above this increases the chance of slippage between the capstan shaft and tape.
I think, if I’m understanding your original post correctly, there may be some question of the tape being sticky because you indicated the transport performs fine initially but then the tape speed in PLAY decreases. This sounds like sticky tape. Do you hear any squealing sounds when the tape is slowing down? Are there any deposits/crud being left on the guides or heads?
jpmorris
Tape Wolf
While checking for crud is definitely a good idea, the fact that it happens at the halfway point sounds to me like the back tension is overpowering the capstan. I was getting this with the B77, after the halfway mark it started to go out of whack as the load distribution between the takeup and supply motors changed. If this is the case, manually pressing the pinch roller into the tape may cause it to right itself temporarily, which would imply a problem with the roller or the roller pressure against the capstan.
hautbois16
Member
Just thinking about the mechanics a bit, an idea of mechanical advantage comes to my mind. When the tape is about half used, the operating diameter of the "supply spool" is considerably less than it was when the supply reel was full. Since the tape transport speed should ideally be controlled at a constant rate by the capstan, that supply reel should need to turn faster in order to keep the tape moving at that constant speed. But what if for some reason there were extra friction in that supply reel's system.
Granted, I am not familiar with your tape deck; but I know that many - and perhaps most - decks have some kind of brake mechanism on the supply reel. On the Sony 377, for instance, the brake is "modulated" by pressure on a lever sticking up in the tape path just left of the erase head. As tape moves in play or record, this system achieves what I'll call a "dynamic equilibrium" in backtension on the tape by easing the brake just enough to maintain only a slight drag on the tape supply reel. If this brake mechanism gets out of adjustment, extra drag might occur as the amount of tape on the supply reel becomes less than half of the reel. I don't know what kind of "clutch" is present on the take-up reel of your deck. On older nonprofessional machines, this clutch might be a felt affair mounted between the take-up reel's platform and a spinning plate below. That system allows slippage so that the speed of the take-up reel can vary from its faster speed at the beginning to its slower speed near the end of the tape. Now if that kind of clutch is present, and if it has slightly too much drag, it might affect tape speed, particularly if there is only one motor for the whole system. If there is a capstan motor serving only for turning the capstan at a very precise speed, then I doubt that the take-up system is the culprit.
Just one more consideration, especially if there is a separate capstan motor: Question: Since the tape plays slower when it is more than half-way through, have you tried immediately mounting a different tape at its beginning and checking tape speed? I ask this question to rule out the possibility of a capstan motor becoming hot and tightening up enough in its bearing to slow the capstan speed slightly. Heat in that motor is not my first thought on your problem; but since I have worked on a few tape decks in my years, that is one problem which comes to my mind.
I hope the ideas from some of us on this list will help you fix your tape deck, and I wish you the best in your recording work. It is a lot of fun!
Granted, I am not familiar with your tape deck; but I know that many - and perhaps most - decks have some kind of brake mechanism on the supply reel. On the Sony 377, for instance, the brake is "modulated" by pressure on a lever sticking up in the tape path just left of the erase head. As tape moves in play or record, this system achieves what I'll call a "dynamic equilibrium" in backtension on the tape by easing the brake just enough to maintain only a slight drag on the tape supply reel. If this brake mechanism gets out of adjustment, extra drag might occur as the amount of tape on the supply reel becomes less than half of the reel. I don't know what kind of "clutch" is present on the take-up reel of your deck. On older nonprofessional machines, this clutch might be a felt affair mounted between the take-up reel's platform and a spinning plate below. That system allows slippage so that the speed of the take-up reel can vary from its faster speed at the beginning to its slower speed near the end of the tape. Now if that kind of clutch is present, and if it has slightly too much drag, it might affect tape speed, particularly if there is only one motor for the whole system. If there is a capstan motor serving only for turning the capstan at a very precise speed, then I doubt that the take-up system is the culprit.
Just one more consideration, especially if there is a separate capstan motor: Question: Since the tape plays slower when it is more than half-way through, have you tried immediately mounting a different tape at its beginning and checking tape speed? I ask this question to rule out the possibility of a capstan motor becoming hot and tightening up enough in its bearing to slow the capstan speed slightly. Heat in that motor is not my first thought on your problem; but since I have worked on a few tape decks in my years, that is one problem which comes to my mind.
I hope the ideas from some of us on this list will help you fix your tape deck, and I wish you the best in your recording work. It is a lot of fun!