why does it slow down???

[MartyMcFly]

Can anyone help a brotha out? What would cause a say Tascam 38-8 to slow down towards the end of a rewind? I cleaned and replaced the 2 rubber washers on the brake and motor solenoids. Is there a certain thing that wears out that needs replacing? Thanks

 

[Lt. Bob]

aren't they supposed to slow down towards the end so there'll be less chance of tape damage?
Not sure about the 38 but I believe some tape decks do just that.

 

[jjones1700]

I would think that all of them, any decent one at least, would slow down towards the end. It would create much more wear on the brake (and premature wear on the brake padding) if it kept a constant rewind speed, not mention the last couple of feet of tape would be shredded from slapping against the face of the deck, head block, and the other reel. Besides, as more tape is loaded on a reel, the more resistance the motor encounters and would slow down anyway if the voltage and amperage remained constant. Perhaps that's how it actually works, I'm no expert.

I would say you are okay, unless you notice a slow down in playback, or if the ffwd/rewind operations get progressively longer.

 

[MartyMcFly]

NO, This is only during rewind. It may happen in FF but i havent checked that yet. But it slows down too much. To where its just a little bit faster than I can spin with my hand. Its too slow. Ive had a 32 and now a 34. They all RR and FF properly. This one's not...

 

[david winter]

I had that problem with different machines and I always found that it was due to friction problems. Sometimes some parts making friction were dirty or accumulated a thin layer of rubber or got polished by natural wear. In these cases I cleaned the affected pieces, and this considerably increased the speed. I had some wheels with some rubber around and this rubber often got polished and dried over the years. With some light solvent I could remove the thin layer of dried rubber and this also fixed the machine. Note that this should only be done with single-level pulleys. If you have a 2-level pulley for example, the speed ratio will change as you reduce (even very slightly) the rubber to get more friction. I had one machine with a leaky motor capacitor. Replacing it totally fixed the problem. I also had another case which had some old grease around the motor axis. This grease somewhat dried over the years and would slow down the motor after heating from friction. Cleaning the axis and lubing with fresh grease / oil also fixed the problem. Lastly, if your machine has belts, their tension is not the only important factor. Make sure they are not "polished" from wear. Flat belts can be reversed (put upside-down) IF they still have a good tension. Without knowing how your machine works it's kinda hard to help you more but those were the problems I encountered so far, although I only play with general consumer decks and a few 1/4" decks ala Revox A77/B77.

 

[Tim Gillett]

What sort of tape are you using?

Tim

 

[cjacek]

It's def not normal for ff or rew to slow down. I'd guess you may have a lot of gunk in the tape path and / or a shedding tape or may be using a very high output tape which is physically harder for your 38 to pull. Maybe? Dunno. Other issues may be mechanical, motor related and a whole host of others I'm not really qualified to speak about. Hey, maybe the brakes are not releasing fully or when you replaced the washers, you screwed something up ? Did the rew / ff work fine before you replaced the washers? Marty, can you post some photos of the tape path ? Lets eliminate the obvious first.

 

[Beck]

In addition to the good advice above keep in mind it is normal for the supply reel (left side) to slow down on rewind towards the end because the diameter of the tape pack is larger. The take-up (right side) reel will speed up during this phase because the diameter is getting smaller. The speed the tape is traveling does not change.

Also, if you use the Return-to-Zero function the transport will actually slow down as it gets close to zero on the counter.

 

[A Reel Person]

The FF/RW is adjustable on the 38, but...

the problem may be in the reel tension adjustments. I'd recommend going thru the reel tension adjustments before messing with the RW speed adjustment.

It stands to reason that if the tensions are out of whack, (esp. too high), the transport functions won't perform to spec. It also stands to reason that many vintage 38's in the field may be fairly out of spec on this and many other adjustments. You should also verify there's not slippage of the reel tables on the motor shafts.

Of course, as mentioned above, you don't go deep until you've eliminated basic tape path friction from the equation. However, a maladjusted or out-of-spec transport may cause an exacerbation of any friction or shed problem.

I believe most home-kept (38) decks of that age would be out of spec on most of the electronics, including record/repro and transport functions. I've been thru the adjustments on a couple of 38's. I take it for granted the average off-the-street 38 needs a full tune-up.

I'd make sure to check the reel tensions first, & adjust as necessary, but you can really give that RW function about as much juice and torque as you want, when it gets down to it. Still, getting the forward and back-tensions just right might eliminate the need to even touch the FF/RW speed control. Try it.

Otherwise, live with it if it's not too annoying. No use in giving yourself a headache about it.

 

[MCI2424]

the problem may be in the reel tension adjustments. I'd recommend going thru the reel tension adjustments before messing with the RW speed adjustment.

It stands to reason that if the tensions are out of whack, (esp. too high), the transport functions won't perform to spec. It also stands to reason that many vintage 38's in the field may be fairly out of spec on this and many other adjustments. You should also verify there's not slippage of the reel tables on the motor shafts.

Of course, as mentioned above, you don't go deep until you've eliminated basic tape path friction from the equation. However, a maladjusted or out-of-spec transport may cause an exacerbation of any friction or shed problem.

I believe most home-kept (38) decks of that age would be out of spec on most of the electronics, including record/repro and transport functions. I've been thru the adjustments on a couple of 38's. I take it for granted the average off-the-street 38 needs a full tune-up.

I'd make sure to check the reel tensions first, & adjust as necessary, but you can really give that RW function about as much juice and torque as you want, when it gets down to it. Still, getting the forward and back-tensions just right might eliminate the need to even touch the FF/RW speed control. Try it.

Otherwise, live with it if it's not too annoying. No use in giving yourself a headache about it.

Yep. Probably spot on.

 

[MartyMcFly]

OK... Here's the report.
I had been using some crap tape just to test recording and stuff and never took it off. But it turns out that even with a New roll of Quantegy 456 made 2 months ago and that one did it too. So I dont think its the tape itself...Or atleast sticky...
I believe just from looking at the machine that the left hub(when looking at the machine) is a little cockeye. I have to fix that. It makes the reel spin a little funny. Also I think I should look at the belts (havent gotten to that yet). I only looked at the solenoids that I mentioned. So there are a few things I need to fix.
Where can I get a decent spring scale? I would like to be able to go out and get it not wait for the mail...

 

[jpmorris]

OK... Here's the report.
But it turns out that even with a New roll of Quantegy 456 made 2 months ago and that one did it too.

Uh...? Are you sure of that?

As for spring scales, I really do need to get one of those myself.

 

[MartyMcFly]

Uh...? Are you sure of that?

As for spring scales, I really do need to get one of those myself.

Yeah...Well its 2007145. I think thats in late May? And it sure does look authentic...

But the thing about the scale...Does Wally-Mort have them?

 

[A Reel Person]

...

This is the best link I could find in a quick search.
http://sciencekit.com/product.asp?SPLID=SPLID01&pn=IG0030881&cmc=HOME_PAGEIG0030881&bhcd2=1188337686
These look adequate & heavy duty enough to do the job, & are relatively inexpensive.
You might find other or better spring scales with a more extensive search.
My spring scale is a bit older & more "scientific" looking model for engineering.
These Ohaus spring scales should do the trick, though. You'll need a couple scales of different values.
The old school spring scale I have is made entirely of metal.

 

[Beck]

Yeah...Well its 2007145. I think thats in late May? And it sure does look authentic...

But the thing about the scale...Does Wally-Mort have them?

No scales small enough at Wally World. They might have fish scales but they go up to 50 pounds, so won't be fine enough.

What is the history of the tape you have? Did you get them both with the machine, and was the new tape sealed in the plastic bag and new when you got it or already open? If it didn’t come with the machine, did you buy the new tape from a reputable source?

Did you clean the tape residue left from the crap tape before you put on the new?

Also check the lifters. If they are worn flat and jagged that is another source of drag. If you had sticky-shed tape they will be full of goop until you clean them.

The plastic reel clampers (hubs) are a weak link on the TASCAM machines. They break too easily. If it’s not tightening down far enough the reel will flop around. It will help if you put the machine on its back until you get a new reel clamper.

 

[MartyMcFly]

Beck...
I bought that tape from a place ***** (I will pm you the name if you like beck) approximately 2 1/2 - 3 weeks after the date on the tape and the box. Both matched. It was 1/2" and in the plastic cases. It did NOT come sealed inside a bag. I think I paid 36-39.00 per roll. The tape seems fine. The machine just needs alignment...Ill be getting on that...

 

[Beck]

Ok, no plastic bag then since it was in the plastic case. So when you opened it was the end of the tape held down on the roll with a piece of hold-down tape, and if so what color was it?

The reason I'm asking so much about the tape is that tape with sticky-shed will mimic all kinds of other problems, including slow rewind.

The plastic cases are nice but they allow people to do the old switcheroo by putting older tape on new reels. Yep, along with all the other pitfalls, we have to watch out for that too these days.

Yeah PM me the place where you got it.

 

[jjones1700]

The plastic reel clampers (hubs) are a weak link on the TASCAM machines. They break too easily. If it’s not tightening down far enough the reel will flop around. It will help if you put the machine on its back until you get a new reel clamper.

I think they all suck. The really bad part is that my brand seems to be going for an insane premium nowadays.