[gareth magennis]

Hi,

quick question.


I have an Ampex ATR100 here that when you rewind a full reel, the machine
does not brake the supply wheel once the tape runs out.
Leaving a full reel at full velocity flapping about for ages.

Should it do so?


I have read the Service Manual but can't find any reference to what is
supposed to happen when the tape runs out.
This has been reported as a fault with this machine.


I know the reel motors do not have brakes, and their primary function is to
keep the correct tension between both reels and the Capstan motor, and can
run backwards and forward to achieve this.
I would guess running backward as a brake at tape runs out should be a
feature.

The only braking I can see though, is the Emergency braking employed on loss
of power during operation, when the motors spool down by driving a lamp via
a relay opening at power loss.
I can't find these lamps to check them, where are they?


I have carried out the tension arm checks as stipulated in the manual, they
all check out fine.

What is a bit weird is that with no tape threaded, moving the supply tension
arm past midpoint causes the capstan motor to operate forwards.
I have no idea whether this is normal or not.


I have a feeling there is a problem here, but am struggling to identify it.




Cheers,


Gareth.

[Scott Dorsey]

Gareth Magennis wrote:
I have an Ampex ATR100 here that when you rewind a full reel, the machine
does not brake the supply wheel once the tape runs out.
Leaving a full reel at full velocity flapping about for ages.

Should it do so?

If you put your finger on the righthand tape guide and pull it toward you,
does it stop?

I have read the Service Manual but can't find any reference to what is
supposed to happen when the tape runs out.
This has been reported as a fault with this machine.

When was the tension adjustment last done on this machine? You will need a
scope and a tentelometer... you CANNOT do the adjustment with fish gauges
like you can with the 440. Go through the whole tension procedure and you
will either find that the problem is solved or you will come to a point
where you can't get some adjustment to come in at all.

This is likely the result of one of the tension servo loops having drifted.

The only braking I can see though, is the Emergency braking employed on loss
of power during operation, when the motors spool down by driving a lamp via
a relay opening at power loss.
I can't find these lamps to check them, where are they?

They are 211 lamps, I believe they are under the top cover. I have never
seen one fail, ever. Your problem is not braking, your problem is a servo
slamming full-on.

I have carried out the tension arm checks as stipulated in the manual, they
all check out fine.

Does this include all the servo adjustments or did you just check the arms
with the tentelometer?

What is a bit weird is that with no tape threaded, moving the supply tension
arm past midpoint causes the capstan motor to operate forwards.
I have no idea whether this is normal or not.

That's how it's supposed to work! You move that, the transport thinks there
is too much slack on the supply side, so it moves the capstan forward to
equalize tension between both sides.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[gareth magennis]

I have carried out the tension arm checks as stipulated in the manual, they
all check out fine.

Does this include all the servo adjustments or did you just check the arms
with the tentelometer?



***********************



This procedure was just to check the tension arm sensors were reading the
position of the arms correctly.

All done on a 5v go/nogo reading from testpoints 5/6 on the Reel Servo PCB
as per manual.




I don't have a tentelometer.

I might get one, though.




Gareth.

[Scott Dorsey]

Gareth Magennis wrote:
This procedure was just to check the tension arm sensors were reading the
position of the arms correctly.

All done on a 5v go/nogo reading from testpoints 5/6 on the Reel Servo PCB
as per manual.

Okay, the whole transport alignment will take an afternoon, and it will
require a scope, a tentelometer, a greenie screwdriver, and the extender
card that was shipped with the machine and ought to be in the card cage
if nobody has scavenged it.

It is a royal, royal pain in the neck. The manual has complete details on
the whole procedure. But the machine will be much easier to use afterward.

Are you located somewhere where you could have ATR come out and do it? Mike
Spitz is gone but he had a couple guys working for him who were okay. Might
be best to have someone show you the procedure.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Scott Dorsey]

Gareth Magennis wrote:
At the moment I am kind of stymied by not having a Tentelometer or a Test
Tape, and the alignment is all over the place at present.
Someone has definitely messed with it since the new heads were fitted, that
may have included the transport.

You need an MRL tape just to do the normal weekly audio alignment, so I would
definitely make that the highest possible priority. You can't do anything
without it. Spend a little extra and get the one with the sweep tones at the
end.

Ask MRL to declare it as "tape recorder parts" which should not have duty.

I'll keep looking for a Tentelometer, nothing I can find in the UK at
present, and anything from the States ends up in huge taxes/charges at this
end, so I don't buy anything from there any more.

You might ask on the Ampex list, someone may have one you can borrow. It's
not something you're going to use very often (unlike the MRL tape) so you don't
need to have it on the shelf if you can borrow one.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Mike Rivers[_2_]]

On 7/26/2018 6:46 PM, Gareth Magennis wrote:
I've looked at buying test tapes many times in the past, but this is not
something to take lightly, given the price and variety, and suitability
for more than one machine.

There is a somewhat confusing variety of flux density/EQ/level etc.

If you haven't already done so, download the "Choosing and Using MRL
Calibration Tapes" paper:
https://www.canford.co.uk/ProductRes...ng%20tapes.pdf

You can use nearly any calibration tape to calibrate any speed and flux
level. Your choice should lean toward the settings that you'll be using
most. That will save you the effort of computing offsets for the various
settings. I don't know if everybody over on your side of the ocean is
still using IEC equalization, but if they are, and you want to be
compatible with other studios using tape, then you should get an IEC
tape. Otherwise, get NAB. And get one for the speed that you intend to
use most of the time.

You have a choice of 200 or 250 nW/m reference fluxivity. 250 nW/m is
about "+2.5" which, these days is the common "standard" level for high
output tapes. Depending on what you're recording, you might want to go
higher than that. If you want to record at "+6," you'd set the playback
level so that the 250 nW/m tape plays back at -3.5 VU (referenced to the
standard nominal +4 dBu). That's easy. If you get a 15 ips tape and want
to align 7.5 or 15 ips, you'll need to do some fiddling when setting EQ,
but there are tables for that.


--

For a good time, call http://mikeriversaudio.wordpress.com

[Scott Dorsey]

Gareth Magennis wrote:
I've looked at buying test tapes many times in the past, but this is not
something to take lightly, given the price and variety, and suitability for
more than one machine.

They are available here in the UK:
https://www.canford.co.uk/MRL-TEST-TAPES


There is a somewhat confusing variety of flux density/EQ/level etc.

For the most part, you can set any configuration with any tape, by using
compensating factors from the MRL book.

But if you get the tape with exactly the configuration you want, you
pretty much set everything to zero, you play back the sweep and the meter
stays solid without moving, and it's a much more rapid process.

I would decide if you want CCIR or NAB (and make sure the switches on
the padnet cards are set for whichever you prefer) and then I would
get the 250 nW/m 15 ips tape for that EQ.

Pick whatever your mastering guys use. That's likely CCIR if they are
in the UK or NAB if they are in the US, but not always.

I would set the playback up for 250 nW/m 15ips and then I would put on a
reel of 468 and set the record up appropriately.

You may someday wish to use other speeds and you might someday want higher
operating levels, but that is a reasonable default configuration.

Note that the tape does vary from batch to batch, so buy enough for a project,
set the machine up for that box, and then when you buy another box check the
record alignment for that new box.

Which recording tape to use is a religious issue but I've been using 468
since Agfa introduced it, and I have nothing but fine things to say about it.
But I'm not into crushing the tape with crazy high levels either.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[gareth magennis]

Oh, forgot, I also bought the equally expensive Sony DAT torque tape.

That was a good buy.

Not sure where that might be now, presumed missing.



Gareth.