AG-440B-8 1" 8-track Enigma Machine

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AG-440B-8 1" 8-track Enigma Machine

Postby dbbubba » Fri Jan 17, 2014 11:21 pm

This is a picture of the AG-440B-8 that I have built from scratch for a fellow who now lives in Berlin.

I call this "The Enigna Machine" because I cannot come up with a clear answer as to why Ampex engineers and management didn't choose to use the larger REEL MOTORS like I installed don this machine.
If you know AMpex AG-440-8 machines then you know that they used the same size REEL MOTORS as the 1/4" and 1/2" AG-440s except they added a TORQUE BOOST and a TORQUE DELAY circuit to the machine.
These circuits assisted the REEL MOTORS as the transport was put into motion.
I have asked many people, including Ampex managers who were there when the AG-440 was still manufactured, but no one can give me a clear answer about why they used the small motors and the compensating circuits.The biggest difference between this machine and an actual factory AG-440-8 is that I have used larger Ashland REEL MOTORS than the stock machines.
This has completely eliminated the need for the TORQUE DELAY and TORQUE BOOST circuitry which were required for the smaller AG-440 REEL MOTORS to be able to handle 1" tape.

In essence I have built the AG-440-8 that Ampex should have built.
The 64 thousand dollar question is: Why did Ampex decide to use the small REEL MOTORS which required the extra circuitry when the larger motors were available and already in use in Ampex video machines and instrumentation recorders.
Still, my client has been super patient because this project started after he was going to buy my Ampex 1" 8-track which was based on a 350 transport fitted with AG-440 channel electronics.
While we were discussing how he would operate the machine with the European AC standard it dawned on me that the machine's AC hysteresis synchronous capstan motor was designed for a 60 hz line frequency.
With the 50 hz European line frequency the machine was going to run slow.

The first plan was to retrofit a DC SERVO CAPSTAN MOTOR, but as soon as I had one in hand I could see that the deck plate needed to have the hole where the capstan pokes through enlarged.
I decided to transfer all of the machine's parts to a spare AG-440B transport.
I was well on my way to completing the machine when a good condition HEAD ASSEMBLY from an AG-440-8 became available.
We bought that and then before I had everything completed even more AG-440-8 parts became available.
The scope of the project just kept growing.

The machine is now complete, but it is in an AG-350 roll-around console with improvised rack rails for the eight channel electronics.
It has definite "prototype" look, but it is 100% functional.
Now, it appears that I will have a spare AG-440 4-track roll-around console available in the next few days.
With four more channel electronics risers and an improvised rear brace the machine could be an actual AG-440-8.
I'd love to see the machine in a proper roll-around console, but I have to pretty well disassemble the entire machine to transfer the parts to the AG-440 type console.
The project has a life of it's own! :twisted:

Talk about building a machine the hard way! :roll:

Danny Brown
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Danny Brown
(I was going call myself Mr. B because I like people to say "MISTER" when they say my name, but then I pitied the fools.)
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Re: AG-440B-8 1" 8-track Enigma Machine

Postby dbbubba » Fri Feb 20, 2015 10:57 am

After a lot of un-expected issues and the work to correct these things this machine is nearly complete and operational.

Over the last year I was able to procure all of the parts to build an actual AG-440-8 roll-around/enclosure.
The only thing that differentiates this machine from an actual AG-440-8 is the way the 39V POWER SUPPLIES are mounted and a different HEAD CABLE BOX.
Both of these items are different because the original AG-440-8 parts were not available anywhere which required me to improvise a solution.

The REEL MOTORS are also the larger type used on Ampex data recorders.
The larger motors eliminated the use of the TORQUE DELAY and TORQUE BOOST circuits that are required on the original AG-440-8 and AG-440C-8 machines.
You can now shuttle tape without start/stop issues and you can even hit the STOP button when the tape is at full speed without spilling any tape!
On almost all AG-440 (and earlier) machines you have to rock back-and-forth with the REWIND and FAST-FORWARD SWITCHES to bring the tape to a stop in the shuttle mode.
Although I still do this by habit, you can just hit the STOP SWITCH and the tape comes to a stop without any tape spillage or and type of tape loop being thrown.
Also, when you hit the PLAY SWITCH the start up is smooth and even.
I would say that the transport handles tape about as well as a properly adjusted MCI JH-110 or JH-24.
BTW... The tension settings and other transport adjustments were pretty much proper before I started making adjustments.
I got lucky?

The biggest issue was that the original HEAD CABLES that I used on the machine in it's original form (the 300 / AG-440 Hybrid version) exhibited too much crosstalk.
I was able to source a set of HEAD CABLES from an Ampex MM-1000 and they were close enough in length to work.
The REPRO HEAD CABLES had the wrong type of termination at one end, but I was able to re-solder the Winchester connector and make everything work.

Another problem was that the HEADS were incorrectly mounted on the HEAD ASSEMBLY we sourced from Taiwan.
The RECORD and REPRO HEADS line up properly with the entrance and exit guides at either end of the HEAD ASSEMBLY, but the tape is positioned wrong on the ERASE HEAD.
The ERASE HEAD has a fixed mounting system, so it actually determines the height position of the other heads and guides.
It isn't all that difficult to set the height of the RECORD and REPRO HEADS, but it does require the wrap, zenith and azimuth to be re-checked and re-set.
Of course, it requires a whole new calibration of the electronics.
It requires a full day of work.

At this point I only have a few minor issues to iron out and the machine is ready to ship.
Danny Brown
(I was going call myself Mr. B because I like people to say "MISTER" when they say my name, but then I pitied the fools.)
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