[[email protected]]

Hello!

I thought to ask here if anyone has more experience on the Technics
RS-1506 reel-to-reel tape recorder. I work for a small library
tranferring old recordings to digital domain. We have only one machine
which has quarter-track heads, the Technics, and I recently discovered
that when I use the machine's slowest speed, 3.75 in/s, the tape
transport is not stable. I was transferring a 7" reel and noticed that
when about half of the tape (from a full 7" reel) was on the take-up
reel, the take-up tension roller was vibrating noticeably, with a rate
of perhaps 5-10 Hz. This would get worse towards the end of the tape,
propably because the take-up reel's rotating speed was getting slower.
When I looked closely, I could see that the take-up reel's rotation
was not stable which led to tape tension (and the tension roller)
vibration.

This vibration was effecting the sound, resulting in modulation in the
loudness of the music. I also suspect that the drop-outs that resulted
were due to this. It seemed that the tape speed was quite stable
because I did not notice any irregularities when watching the
stroboscopic thingy on the reversing roller, so the effect on sound
must be from unstable tape tension. Do you have any idea what could be
the cause, and is it repairable (I've read that there are no spare
parts avalilable)? I haven't noticed this with higher tape speeds. At
the time I had a plastic 7" supply reel and metallic 7" take-up reel,
same hub radius. I would gladly use another machine if we just had
one. Another department of the same institution owns a similar
machine, but I went to test it last week and it was so completely
busted that it won't be very useful even as spare parts source.

There's also another thing about this machine. When digitizing tapes,
I always adjust the azimuth for every tape I transfer. To my
knowledge, this is standard practice when digitizing a heterogenic
collection of tapes recorded on various recorders. On this Technics, I
don't do that because it seems there is no single azimuth-adjusting
screw for the heads. Also the guy who has serviced this machine said
that it's not that simple for this machine. Do you agree with this?
I've already noticed that not adjusting azimuth has a negative effect
on the quality (it's easily detected with tapes that have been
recorded "in stereo" from a mono source). The problem is that we don't
have the means of calibrating the machines (we had it done elsewhere),
so I don't want to touch anything else but the azimuth.

ps. I read on this forum messages about trouble with this recorder,
namely head selector switch and left tape-source monitoring selector
switch failing. We just had this in service for head selector switch
failing (the switch was removed and the machine is now permanently in
4-track mode) and I have noticed that the *left* tape-source switch
cracles when it is moved. It's still working, but perhaps not for
long. The other department's RS-1506 had also the same two switches
broken down. I sense a trend here.

[William Sommerwerck]

The tension roller is, as far as I know, a passive device. There are no
electronics controlling it.

This sounds like (duh) a mechanical problem that's speed-sensitive. (I
assume it doesn't occur at higher speeds.) It could be due to some problem
with the tension roller (dirt? wear?), or possibly incorrect tension (too
low? too high?) on the take-up reel.

The latter seems more likely, as the problem occurs as the reel fills up. If
this is correct, you should see the same effect at 7.5ips with less tape on
the takeup reel. However, you say this doesn't occur.

There's something else you might try (though it's a stab). Find 7" reels
with large hubs, and make your transfers using those tapes (assuming they're
short enough to fit).

[Mike Rivers]

On Oct 17, 5:50 am, "
wrote:

I work for a small library
tranferring old recordings to digital domain. We have only one machine
which has quarter-track heads, the Technics, and I recently discovered
that when I use the machine's slowest speed, 3.75 in/s, the tape
transport is not stable. I was transferring a 7" reel and noticed that
when about half of the tape (from a full 7" reel) was on the take-up
reel, the take-up tension roller was vibrating noticeably, with a rate
of perhaps 5-10 Hz. This would get worse towards the end of the tape,

If you know about aligning the azimuth, you probably know about
cleaning the heads and guides, and probably also know about sticky
shed syndrome. But just in case, have you made sure that a guide or
head hasn't got sticky? If not from gooey tape binder, maybe a piece
of splicing tape? Your jerky tape movement might be a result of the
tape intermittently sticking and letting go. That's more prevalent at
low speed than at high speed.

[[email protected]]

On 17 loka, 15:11, Mike Rivers wrote:
On Oct 17, 5:50 am, "
wrote:

I work for a small library
tranferring old recordings to digital domain. We have only one machine
which has quarter-track heads, the Technics, and I recently discovered
that when I use the machine's slowest speed, 3.75 in/s, the tape
transport is not stable. I was transferring a 7" reel and noticed that
when about half of the tape (from a full 7" reel) was on the take-up
reel, the take-up tension roller was vibrating noticeably, with a rate
of perhaps 5-10 Hz. This would get worse towards the end of the tape,

If you know about aligning the azimuth, you probably know about
cleaning the heads and guides, and probably also know about sticky
shed syndrome. But just in case, have you made sure that a guide or
head hasn't got sticky? If not from gooey tape binder, maybe a piece
of splicing tape? Your jerky tape movement might be a result of the
tape intermittently sticking and letting go. That's more prevalent at
low speed than at high speed.

Thanks for the tip! Yes, I know about sticky shed and I clean the tape
path daily. I didn't notice any extra stickyness in the path at the
time but I think I'll have to investigate a bit more. I haven't
actually noticed any sticky tape this far, but some might have gone
unsuspected because statistically I should have seen some already (the
tapes are from about 1960 to late 80's and archive conditions are not
optimal). I have thought that if I came across a sticky tape it would
squeal and just not play, so I'm perhaps expecting too drastic
symptoms.

And to William: Thanks for the reply, but I think you are thinking
this the wrong way around. if I used reels with a larger hubs the
reel's rotation would be even slower and the problem would be worse.
That's assuming that this has something to do with the rotational
speed of the take-up reel.

[Scott Dorsey]

wrote:

I thought to ask here if anyone has more experience on the Technics
RS-1506 reel-to-reel tape recorder. I work for a small library
tranferring old recordings to digital domain. We have only one machine
which has quarter-track heads, the Technics, and I recently discovered
that when I use the machine's slowest speed, 3.75 in/s, the tape
transport is not stable. I was transferring a 7" reel and noticed that
when about half of the tape (from a full 7" reel) was on the take-up
reel, the take-up tension roller was vibrating noticeably, with a rate
of perhaps 5-10 Hz. This would get worse towards the end of the tape,
propably because the take-up reel's rotating speed was getting slower.
When I looked closely, I could see that the take-up reel's rotation
was not stable which led to tape tension (and the tension roller)
vibration.

I am assuming the problem is happening with all tapes and not just one.

Replace ALL rubber parts on the machine. Pull the capstan motor,
clean the bearings and lubricate them thoroughly with a light turbine
oil (Castrol OC-11, or Zoom Spout Oil from Ace Hardware, or Royal Purple
Synfilm 32). Disassemble and clean the brakes and if you can replace
the brakes, do so. Put a drop of oil on the reel motor bearings top
and bottom while you are at it. Anything that looks like an idler,
disassemble and clean it. Lubricate idlers with a lighter oil (16 cs
or lighter... watch oil will do nicely).

Once you have done this maintenance (and this is recommended on an annual
basis for the most part), then you can try a tape and see if you have a
problem. That's when the actual diagnosis begins, and it will probably
start with checking the static tape tension.

But that sort of stiction problem usually has to do with brake issues,
dirty guides, or some sort of belt-resonance issue with the tape path.
Idlers exist to break those resonances up, and if they get gunked up
they don't work right.

There's also another thing about this machine. When digitizing tapes,
I always adjust the azimuth for every tape I transfer. To my
knowledge, this is standard practice when digitizing a heterogenic
collection of tapes recorded on various recorders. On this Technics, I
don't do that because it seems there is no single azimuth-adjusting
screw for the heads. Also the guy who has serviced this machine said
that it's not that simple for this machine. Do you agree with this?

It's a pain, but it's not THAT hard. There's no reason not to do it.
You really need to adjust the azimuth for transcription work.

I've already noticed that not adjusting azimuth has a negative effect
on the quality (it's easily detected with tapes that have been
recorded "in stereo" from a mono source). The problem is that we don't
have the means of calibrating the machines (we had it done elsewhere),
so I don't want to touch anything else but the azimuth.

So spend the money and buy an alignment tape. You only need one for
all speeds, if you're willing to use some fudge factors.

ps. I read on this forum messages about trouble with this recorder,
namely head selector switch and left tape-source monitoring selector
switch failing. We just had this in service for head selector switch
failing (the switch was removed and the machine is now permanently in
4-track mode) and I have noticed that the *left* tape-source switch
cracles when it is moved. It's still working, but perhaps not for
long. The other department's RS-1506 had also the same two switches
broken down. I sense a trend here.

Clean them with Cramolin. If that doesn't do it, replace the switch
assembly with a small gold-contact switch. C&K has some locking
gold-contact types that Digi-Key sells. It'll take some mechanical
tinkering to make it look nice, though. The problem is that the switch
contacts get dirty, and with fractions of a microvolt it doesn't take
much to screw the signal up.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[William Sommerwerck]

And to William: Thanks for the reply, but I think you are thinking
this the wrong way around. if I used reels with a larger hubs the
reel's rotation would be even slower and the problem would be worse.
That's assuming that this has something to do with the rotational
speed of the take-up reel.

You're right, in principle, but we don't know fer shure exactly what's
wrong. I'm a believer in the philosophy of "try anything". It sometimes
works.