Tascam 48-OB SLOW Playback

  • Thread starter Thread starter saturatedistortion
  • Start date Start date
S

saturatedistortion

New member
Hello all! I'm sorta new to this forum and I was hoping some of you experts could share your knowledge with me on a issue that i'm having. So my Tascam 48 plays VERY slowly when in playback mode. When in fast forward or rewind there are no apparent speed issues and it seems normal. But when I initiate playback it's like I just activated Turtle Mode :facepalm: I just had the gooey pinch roller rebuilt, believing that was the cause, but the problem still persists. I bought this machine locally a few months ago for a very good deal and have yet to record or playback with it. I have four reels of Quantegy 456 and one reel of BASF SM 900 that I also bought locally and tested the machine with. Some sources attribute the slow playback to dry tape but at this point i'm just unsure of the cause. I would really like to just get down to the bottom of the problem and start recording on my machine already. If anyone who has any expertise on this could share their insights and help me troubleshoot I would greatly appreciate it. I can also upload pictures and video of the machine if that'll help. Thanks!
 
Usually I'd suggest checking the capstan belt, but unfortunately I believe the 48 is direct drive. What might be the problem is the pinch roller pressure - strictly you're supposed to adjust the roller pressure after replacing the pinch roller anyway. Does it work better if you push the roller against the tape by hand? (you'd want to hold it by the cap)
 
Thanks for the responses guys. @Jpmorris, I will try putting pressure on the pinch roller and i'll check back with my results. @theghostoffm the tape that I currently have does not display any of the typical signs of sss, but i am no expert. It does not shed nor is it sticky. They are also formulas (Quantegy-not Ampex, BASF) which I thought were not prone to that problem. I would like to buy brand new tape but i am hesitant to invest more into the machine if the root of the problem is elsewhere. I have also been discussing this issue with Rolf from Vintage Texas and I was advised to check the capstan motor speed to see if that speeds anything up. I'm going to try all these things today and check back. My fingers are crossed! Thank you all again!
 
Depends on the provenance of the tape. Quantegy stuff should be good, as long as it actually is what it claims to be on the box. (If it's 2nd-hand you can't always be sure since something else may have been spooled onto the reel). I think the BASF stuff should be good too, again - assuming it's what it claims to be.

Actually, I believe BASF tape embossed the tape formulation on the backcoated side. I have some 1/4" tape like that, with SM468 all down it, but I don't know if they did this with 1/2" tape.
 
Some questions:

1. How slow is turtle mode ? half ?
2. Is the slowness variable or fixed ? so you can record and it plays the same or it is not constant ?
3. Does it come to a stop ?
4. Was it like this when you bought it ? or it started later ?
5. From all the different tapes that you have, is the behavior identical ?
6. Can you send close pictures of the tape lifters/heads ?
7. Are the tension roller arms free to go up and down when moved with your finger ? how stiff are they?
 
@jpmorris Yes I think you're right. I need new tape to properly test it out. The reels that I have, although don't seem to shed, seem like they were stored in a garage or attic.

@fgonza2
1. When in play the machine is very slow. While playing the digital counter will add 1 second every 40 seconds or so.
2. The slowness is fixed and steady, but I have not tried recording on it.
3. It does not stop.
4. It has been like this since I bought it. I have never been able to get it to play properly.
5. Yes, I have tried all the tapes and problem is synonymous with them all.
6. I will attach some close up pictures very shortly.
7. Yes, the tension roller arms seem to move very freely and unconstrained.
 
Has it every played back differently or always like this since you bought it? I ask because you may have a 48 that was set up as a logging machine.

Quote: Post and call logging tapes were commonly recorded at 17⁄8 ips or even 15⁄16 ips.

Cheers
Alan.
 
Hey Alan, before I purchased the 48 I couldn't really test it since I had no tapes at my disposal. Since the heads looked very good and the price was right I decided to get it without properly testing it out first. The previous owner could not tell me much about it other than it came from a friend who used it for recording and before that it came from a local court house. It being used as a logging machine sounds like an interesting theory. I'm completely new to this medium so I didn't even know about logging. How can I see if that is the reason for the my issue and where should I start to fix the speed?
 
If it is a logging machine, it might be internally set to run at cassette play speed, 1 7/8th IPS, for voice recording quality only.

Hopefully there's an internal jumper to set it back to 15 IPS but you'd need the service manual to see how that's accomplished.

From memory, the machine would be labelled as as a 48L if that were the case. OB, usually means Only Balanced...no RCA jacks, just XLR's on the back.

Cheers! :)
 
Esar said:
Hey Alan, before I purchased the 48 I couldn't really test it since I had no tapes at my disposal. Since the heads looked very good and the price was right I decided to get it without properly testing it out first. The previous owner could not tell me much about it other than it came from a friend who used it for recording and before that it came from a local court house. It being used as a logging machine sounds like an interesting theory. I'm completely new to this medium so I didn't even know about logging. How can I see if that is the reason for the my issue and where should I start to fix the speed?
Click to expand...

If it came from a court house it is almost defiantly a logging machine running at a slow speed. Someone will have a manual here, come on guys.

Alan
 
Good news, I have a manual! I'm looking through it right now for more info. I'll check back as soon as I find something. Thanks for all the input guys!
 
Run the following experiment:

1. Power on the machine and in STOP mode with tape loaded, touch slightly the capstan with your finger to feel the speed. (the white axle that rotates)

2. With the finger still on the capstan hit PLAY with the tape. Do you feel a significant reduction on the capstan speed when you hit play or it stays roughly the same ?

If it stays the same, the issue is not the tape and it's related to capstan speed control or as someone mentioned setup as logging machine.
 
Okay, BIG UPDATE! As I mentioned earlier I was looking through the service manual to find out how to adjust the speed. The manual stated that if the speed had diverged from specification then to check pinch roller pressure and take up tension. So I started tinkering around for the first time inside the machine. I tried turning the trimmer resistors for the take up reel tension and VIOLA! The speed of playback increased a considerable amount!!! But it's still not up to normal (15ips). Before I did this, the capstan would remain at the same consistent speed when in stop and play. Now it actually SPEEDS UP when in play!!! This is quite a breakthrough guys. I'm glad that I'm starting to see some results but I'm still trying to find out how to get it back to normal 15ips playback mode. What do you think?
 
ok, so based on what you describe, you have a tension adjustment problem. The capstan should speed up in stop and slow down in play, not the other way around, in case your tension is too high. Follow the manual to adjust the tension in play mode that should get you there.

When the machine is in STOP mode, the capstan speed is not linked to the tension adjustment in anyway, so if the back tension in the supply reel is too high it will slow down the tape and the capstan. So you need to adjust tension for both take up and supply reels. What you've done so far is increase the tension in the takeup reel, go to the manual and follow the tape tension servo adjustment section, that should get you there. Good news, this is an easy fix.
 
I just bought a Tascam 48 and it is doing some similar things, however, it will stop in the middle of playback. I bought a used reel of 456 on eBay just so I can test it out before purchasing a new reel, alignment tape, etc $$$. The tape was playing and i could hear all the tracks just fine, but after about 10 seconds of slowing down it would just stop. Is the capstan supposed to stay moving at all times unless in stop mode? I did notice that once it stopped, I would hit play again and it would not play, nor was the capstan moving.

Any advice is greatly appreciated, as this is my first step into tape machines.

Thanks,
Adam
 
456 tape is suspect from the git go. Did it come in a box? If so where is the ampex label on the front? center? or bottom? is the date code sticker still on the box?

The capstan should be moving all the time, at the same speed. The reason the capstan is always moving is so when the machine it dropped into play the capstan is already up to speed, and you arent waiting for that to happen. On some pro machines the capstan is stopped during the "load" function, just to make the threading a bit easier. but once load or stop are pressed the capstan starts and the pinch roller moves towards the capstan, but just shy of touching it. I dont have a 48 but I have its predecessor the 38. Capstan always runs, same speed all the time.

*edit. If this machine is new to you, and you are having these issues, the capstan drive belt is a good place to investigate. The Tascam belts deteriorate over time, sometimes getting loose and hardening, other times turning into sticky goo that ends up making a big mess on the capstan drive motor.
 
Thanks for the quick reply! The Ampex 456 Grand Master did come with a box. The label is on the front right side of the reel. I see a 93271 on the box sticker. Is that the date code? Total nube here, haha :facepalm: I do have the manual AND service manual with schematics. I will check and see if the 48 has a capstan belt. I think I read somewhere that it is 'direct drive'?

Adam
 
Uuuum.....according to my service manual, there is no belt. It's a bolt-on motor with a ribbon cable to power it.
 
Okay, I just ran through the transport functions with no tape, holding the tension arms up. The machine and the reels are doing what they should, and the capstan is constantly moving. It must be something with the tape then I suppose.
 
You must log in or register to reply here.

Similar threads

R
Tascam 38 R+P Card Potentiometer Problems
Replies
11
Views
1K
sweetbeats
sweetbeats
C
Tascam 38 Capstan Assembly Making Strange Noise.
Replies
7
Views
850
carsarebad
C
P
First Reel to Reel Machine: Fostex A4
Replies
4
Views
748
rob aylestone
rob aylestone
M
Tascam 48 Issues
Replies
15
Views
2K
Mischmaschine9000
M
christiandaelemans
tascam 38 and m512: very quiet tape playback
Replies
16
Views
1K
christiandaelemans
christiandaelemans
Back
Top