tape deck speed problems

[tempus fugit]

Hey all;

I have 2 tape decks with different speed problems:

1. Yamaha KX360 - the speed has slowed so that it is roughly one semitone
below pitch, but is consistent,

2. Technics RSB18 - speed fluctuates - it seems mostly like it gets slower
then picks up again, at various points in the tape.

So......

Any thoughts on how to correct the speed issues on these decks or what I
might look for? Are there any common causes for this type of behaviour? I
checked inside the Yamaha and found that it doesn't (unless it eluded me)
have a speed control on the PC board.

Thanks

 

[Michael Ware]

Hey all;

I have 2 tape decks with different speed problems:

1. Yamaha KX360 - the speed has slowed so that it is roughly one semitone
below pitch, but is consistent,

2. Technics RSB18 - speed fluctuates - it seems mostly like it gets slower
then picks up again, at various points in the tape.

So......

Any thoughts on how to correct the speed issues on these decks or what I
might look for? Are there any common causes for this type of behaviour? I
checked inside the Yamaha and found that it doesn't (unless it eluded me)
have a speed control on the PC board.

Thanks

For the Yamaha, look on the back of the drive motor itself, speed adjustment
pot may be there.

For the Technics...lots of thing can slip or bind causing these symptoms,
try a different cassette if you haven't already

 

[tempus fugit]

Thanks Michael - I'll look into the Yamaha. As for the Technics, I've had
this problem with a few tapes, so I assume that it's not the tape itself.

 

[JR North]

The Technics deck will have the speed control in the motor. Loof for a
small hole in the motor's end plate. Plasic screwdriver now...
JR

 

[Ken G.]

By now many tape decks are experiancing motor wear out . Try the speed
adjustement first .

 

[b]

tempus fugit ha escrito:

Hey all;

I have 2 tape decks with different speed problems:

1. Yamaha KX360 - the speed has slowed so that it is roughly one semitone
below pitch, but is consistent,

2. Technics RSB18 - speed fluctuates - it seems mostly like it gets slower
then picks up again, at various points in the tape.

So......

Any thoughts on how to correct the speed issues on these decks or what I
might look for? Are there any common causes for this type of behaviour? I
checked inside the Yamaha and found that it doesn't (unless it eluded me)
have a speed control on the PC board.

Thanks

the yamaha sounds like a case of adjustment. How old is the technics?
that sounds like the motor, or more precisely the small controller chip
inside it. I had to replace the motor on a technics (forget the model)
which had about 7 years heavy use on it in a radio station (that was
running too fast and varying).
Recently saw an early 80s sanyo where the motor would either slow down
to about half speed (again, varying) all of a sudden , or simply stop.
In both cases the motor was at fault but you never know - I suggest
you clean, check braking and gearing and replace belts first.
good luck
-B
-B.

 

[tempus fugit]

Great, thanks for all the suggestions guys.

Michael, the speed adjustment inside the motor did the trick - quick and
easy repair (for a change). JR - plastic screwdriver? oops I already uses a
jewellers screwdriver that was metal. Could that cause some problems?

The technics is a good 25 years old, but hasn't seen a lot of use in the
past 10 or 15. I'll look into these things that have been suggested here. I
wonder if maybe the belts are getting a bit worn and stretched too. I should
also say (to add to the other anwers given here), that I once repaired a
different Yamaha deck with similar problems as the Technics by replacing a
few high ESR caps. Took a while to get to that conclusion, but as far as I
know it did the trick.

Thanks again

 

[n cook]

Hey all;

I have 2 tape decks with different speed problems:

1. Yamaha KX360 - the speed has slowed so that it is roughly one semitone
below pitch, but is consistent,

2. Technics RSB18 - speed fluctuates - it seems mostly like it gets slower
then picks up again, at various points in the tape.

So......

Any thoughts on how to correct the speed issues on these decks or what I
might look for? Are there any common causes for this type of behaviour? I
checked inside the Yamaha and found that it doesn't (unless it eluded me)
have a speed control on the PC board.

Thanks

This is how I calibrate a deck once the speed regulator is found

Requirements: a 1KHz test tape or a recording of an accurate
1KHz tone made on a known good tape unit and played back on that machine
to check, and an audio signal generator
with a fully floating output ie no dc reference if not then de-couple the
output
with a couple of capacitors. Parallel together one channel of the phones
output of the tape and the output of the sig.gen. and a set of headphones
in mono (L and R connected). With approximately equal sound levels
you should get unmistakeable beat note .Reduce the beat to a minimum by
changing the speed regulation of the cassette unit motor.

The other tape deck - can be due to anything that moves

 

[Arfa Daily]

This is how I calibrate a deck once the speed regulator is found

Requirements: a 1KHz test tape or a recording of an accurate
1KHz tone made on a known good tape unit and played back on that machine
to check, and an audio signal generator
with a fully floating output ie no dc reference if not then de-couple the
output
with a couple of capacitors. Parallel together one channel of the phones
output of the tape and the output of the sig.gen. and a set of headphones
in mono (L and R connected). With approximately equal sound levels
you should get unmistakeable beat note .Reduce the beat to a minimum by
changing the speed regulation of the cassette unit motor.

The other tape deck - can be due to anything that moves

That's very novel - I've never heard it done like that. I've got a strobe
tape that I bought from CPC I think it was, years ago. It has a little
window in it, and a stobe disc with two rings, one for normal speed and one
for high speed dub. Very effective. I also have " Clint Eastwood " by The
Gorillaz recorded on my workshop test tape. This has a very ' natural ' beat
speed, and I find that I can set tape speed perfectly by ear, just using
this piece of music. I always check afterwards with the strobe tape, but
it's uncanny just how accurate the body's sense of timing is.

Another way I've seen of doing it with a 1kHz test tape, is to just put a
frequency counter on the end of the deck. Too fast, freq too high. Vice
versa for too slow.

Arfa

 

[n cook]

That's very novel - I've never heard it done like that. I've got a strobe
tape that I bought from CPC I think it was, years ago. It has a little
window in it, and a stobe disc with two rings, one for normal speed and one
for high speed dub. Very effective. I also have " Clint Eastwood " by The
Gorillaz recorded on my workshop test tape. This has a very ' natural ' beat
speed, and I find that I can set tape speed perfectly by ear, just using
this piece of music. I always check afterwards with the strobe tape, but
it's uncanny just how accurate the body's sense of timing is.

Another way I've seen of doing it with a 1kHz test tape, is to just put a
frequency counter on the end of the deck. Too fast, freq too high. Vice
versa for too slow.

Arfa

You don't even have to have both headphone sound sources anywhere near equal
level and the beats are still extremely noticable. Putting one source to one
ear and the other to the other ear to produce beats in your head is not so
straightforward.

 

[tempus fugit]

That's a good idea for setting tape speed. Since I'm a musician, I just get
my guitar in tune to A440, pop in a known good tape, and play along with the
tape, setting the speed to make sure the pitch is correct.

 

[n cook]

That's very novel - I've never heard it done like that. I've got a strobe
tape that I bought from CPC I think it was, years ago. It has a little
window in it, and a stobe disc with two rings, one for normal speed and one
for high speed dub. Very effective. I also have " Clint Eastwood " by The
Gorillaz recorded on my workshop test tape. This has a very ' natural ' beat
speed, and I find that I can set tape speed perfectly by ear, just using
this piece of music. I always check afterwards with the strobe tape, but
it's uncanny just how accurate the body's sense of timing is.

Another way I've seen of doing it with a 1kHz test tape, is to just put a
frequency counter on the end of the deck. Too fast, freq too high. Vice
versa for too slow.

Arfa

Thought experiment.
Is it possible with my technique to make a test tape using frequency counter
cross-checked sig gen and one good tape deck.
If the deck is actually out a bit it will still play back on itself
correctly methinks.
Do I require 2 good decks and make a tape on each and try in the other ,
then unless both are out by the same amount and both up or down by that
amout then they should all be close to zero beats in all 4 permutations ?

 

[Jim Land]

Thought experiment.
Is it possible with my technique to make a test tape using frequency
counter cross-checked sig gen and one good tape deck.
If the deck is actually out a bit it will still play back on itself
correctly methinks.
Do I require 2 good decks and make a tape on each and try in the other
, then unless both are out by the same amount and both up or down by
that amout then they should all be close to zero beats in all 4
permutations ?

You're right, if you record on a slow deck, and it plays back at the same
slow speed, the tone it plays back will be the correct fequency but you
won't have a valid test tape. Your analysis of two tape decks is
correct.

 

[Arfa Daily]

Yes, I think that the way to do it would be as you say, with the 4
permutation cross-check. However, these tapes are readily available still, I
think, already recorded on a known correct speed deck. I have a full set of
test tones, torque measure, tape path mirror, 0dB record level etc

Arfa

 

[n cook]

Yes, I think that the way to do it would be as you say, with the 4
permutation cross-check. However, these tapes are readily available still, I
think, already recorded on a known correct speed deck. I have a full set of
test tones, torque measure, tape path mirror, 0dB record level etc

Arfa

It begs the question , how do the manufacturers check the goodness of their
test tapes?
I seem to remember a picture in a manual or publication showing via some
magnetic ink or similar, contrasting bands along a piece of magnetic tape
carying a constant tone , perhaps they can use that process to physically
count and measure the visualised bands on a sample of their tapes.

 

[Michael Ware]

It begs the question , how do the manufacturers check the goodness of their
test tapes?
I seem to remember a picture in a manual or publication showing via some
magnetic ink or similar, contrasting bands along a piece of magnetic tape
carying a constant tone , perhaps they can use that process to physically
count and measure the visualised bands on a sample of their tapes.

I remember the standard rate of tape travel over the heads is 2
inches/second or something. Maybe they check a 'master' deck, mechanically,
then use it to make master tapes.

 

[Arfa Daily]

I remember the standard rate of tape travel over the heads is 2
inches/second or something. Maybe they check a 'master' deck,
mechanically,
then use it to make master tapes.

I actually went looking on the net for the Konig tapes that I have to see if
they were still available, and the only reference I could find was in New
Zealand, so I reckon that I'd better start taking more care of mine ... !!

Arfa

 

[n cook]

I remember the standard rate of tape travel over the heads is 2
inches/second or something. Maybe they check a 'master' deck, mechanically,
then use it to make master tapes.

I tried that one time making a length of tape in a cassette, length of tape
from head read position at start to end an exact length for 1 7/8 inches/sec
, so counting seconds but results did not agree with my commercially
produced 3.2KHz test tape (stretched?) and didn't explore any more.