asking advices One of a kind TAPE magentic recorder repurpose Project

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ion

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hello all,
this is super early stage but i have a very uncommon project at the table.
my dream reforder and the last one if ever i will get is a nagra sn. While droolimg over it i stumbled over a military data recorder that i got cheap.
iam fascinated by the heavy duty construction and build. Basicaly this is a loop recorder wich i assume records at 3¾ ips and on 1/4 track tape. But its possible its rather between 3¾ ips and 7½ ip.
the heads are Nortronics. First would be erase followed by rec and play (i think so).
i am unsure if data heads are different from audio but i dont think so, its magnetics after all.
degradation through the signal flow is another story (bias).


so obviously my startpoint is powering. I assume it runs on 24V DC but its a wild guess really.
how would you start with powering the thing?
next will be finding out signal flow and pins on the connector.
iam not sure if i should skip the board for audio and direct wire to the heads and build external impedance matching and amplification around it or if i should follow the signal flow.
reason is, its probably made for data not voice.
i have no clue but doubt there is any bias. but would be very happy to be proven otherwise as we know tape rec without bias isnt so cool.

so plan is to build impedance/amplification around it.
Simple start stop (even if its power on/off).
if possible motor speed (i suppose a potentiometer between the 2 motor wires at E12 E13).
head manipulation (maybe) a way to disable the erase and rec heads. (mu shield tape?)
on the pcb side, the erase head sits in the upper left corner. Theres also a grounding lug.

if some of your experts on here have ANY advices or are able to make sense of the pcb and signal flow, please enlight me.
i suppose the actual signal goes through the 2 little hammond (transformers?)

the whole unit is super small. Imagine width/length of nagra sn and probably 2-3 times the height.

the purpose is field recording, music recording, looping, delay (for delay i have a echo matic diy controller wich is build for 3 head tape devices)
i am not sure if the heads are mono or stereo.
 

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ruffrecords

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Some data recorders need a response down to dc. To achieve this they use FM recording - so a tone (carrier) is recorded and FM modulated by the data. Not saying this is the case for your unit but just something to be aware of.

Cheers

ian
 

ion

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Very likely but how to define „need“ since it would need that for data rec wich i would skip over by hacking if i manage.
 

ruffrecords

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Very likely but how to define „need“ since it would need that for data rec wich i would skip over by hacking if i manage.
Well " military data" is a big clue. Are there any markings on it which might give another clue?

Cheers

ian
 

ion

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It is a crash flight data recorder and demilitarisation shall be the goal:)
from leigh instrumemts Canada.

its just the tape unit of a black box. No clues about voltage for example
 

ion

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Well " military data" is a big clue. Are there any markings on it which might give another clue?

Cheers

ian
I dont think this will give more info but here you go
 

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ion

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It gives you the part number and the manufacturer. You could always contact them and ask for a schematic.

By coincidence I worked on the Tornado project in the early 70s on the ATE system.

Cheers

Ian
Hah how crazy is that.

yes i actually feel very motiviated to upcycle a military item, part of a destruction focused thing to a weird field recorder playing back loops of forest wildlife. Yeah i am coming from artist background but not into citsch*

i was thinkg about contacting them but the pcb is very minimalistic and driving 12v in for a start and trying to monitor the heads, a shematic wouldnt help me personaly and i couldnt make much sense out of it.
maybe thats just introverted BS Tho.
 

ion

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Nobody wants to take a closer look and/or has experience with tape magnetics to get some ideas my way?
 

Mixermend

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Are there any clues from the motor to determine the voltage required?
My dream tape machine is the Nagra T - which is just beautiful. This was certainly available as an instrumentation version, people have purchased these thinking that they could be used for audio - I wonder how they got on?!!
 

ion

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Are there any clues from the motor to determine the voltage required?
My dream tape machine is the Nagra T - which is just beautiful. This was certainly available as an instrumentation version, people have purchased these thinking that they could be used for audio - I wonder how they got on?!!
Nup.

i researched and am not sure if read 24v somewhere for some tape black box. I think if i start with +12 and test pins i cant really destroy ánything. Its obsiously fed by the plane but sureley stepped down to common dc for tape recorders that size.

i think the big data recorders are much more trouble for audio but this little thing has almost nothing so less interference to my understanding. Anyone knows if data / flight recorders also use bias HF?


the colored wires are the playhead if i follow the brown one, it goes - cap - resistor - resistor cap team (i think so, the little black before the hammond) - hammond (is that a minimtransformer? says T2 so i suppose). and (maybe) to yellow wire - to out. Makes the tiny hammond the out stage.

the red goes straight to the cap that i think meets the resistor influenced signal from brown.

blue and green are less obvious. I can follow green to one resistor and blue to one cap followed by resistor.

does that say anything to someone?






thinking of adding a small preamp and outstage where the data conector is and keep everything very small. As it is we are talking about 13x11cm and it should stay as small as possible for field rec. i have a vtb 9046 line xformer left that i could use aswell as some small DI box one. I suppose tape recorders have a more gain pre then out stage? Anything special about tape preamps? Any common impedances known?
 
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ion

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So iam looking at small nagra pcbs right now, the preamps arent too expensive but can someone make out if my recorder has things like bias osc, tape rec amplifier, playback amplifier as i suppose i need tape eq amplifiers.
 

ruffrecords

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Looking at the PCB I can see the following:

1. A couple of Hammond transformers type 101J. I am sure you can look these up
2. A 747 dual op amp
3. Three metal can op amps (cannot see type numbers)
4. A metal can transistor
5. A high wattage 25 ohm resistor near the motor
6. Some it not all of the wiring from the heads goes direct to the connector (not helped by the wires all being the same colour)
7. three wires from the connector go to the big caps.

From which I conclude:

1. I see no sign of a bias or erase oscillator
2. I see no sign of a power supply, just some decoupling caps.
3. The 25 ohm resistor is probably part of a servo used to stabilise the motor speed.
4. Hammond transformers probably provide a balanced floating input and/or output

Beyond that you will need to reverse engineer the PCB and draw its schematic.

Cheers

IAn
 

ion

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Looking at the PCB I can see the following:

1. A couple of Hammond transformers type 101J. I am sure you can look these up
2. A 747 dual op amp
3. Three metal can op amps (cannot see type numbers)
4. A metal can transistor
5. A high wattage 25 ohm resistor near the motor
6. Some it not all of the wiring from the heads goes direct to the connector (not helped by the wires all being the same colour)
7. three wires from the connector go to the big caps.

From which I conclude:

1. I see no sign of a bias or erase oscillator
2. I see no sign of a power supply, just some decoupling caps.
3. The 25 ohm resistor is probably part of a servo used to stabilise the motor speed.
4. Hammond transformers probably provide a balanced floating input and/or output

Beyond that you will need to reverse engineer the PCB and draw its schematic.

Cheers

IAn
From your experience in that field you dont happen to know the common voltage these devices are fed?
i am thinking portable reel commons like 7,5-10V
 

ion

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Got it spinning 9v block directly to the motor pins, red to red and black black wasnt the way and after a spin backwards had to dissasemble fix tape chew.

Not exactly silent but i think similar to nagra and uher portables

looks like 3 3/4 ips
 
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Disco Volante

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Hmm, judging from the 3rd pic it seems to be actually made in Friedrichshafen Germany or have something to do with the company whose name is hidden by the lid-edge. Maybe if you can get a peek at the top of the label, we'll know who made it?
Looking at the other pics, the heads seem to be all yellow wire, two wires for each=mono. Erase, record, play. If you can measure impedance and resistance, you'd get a clue as to what they're about.
It looks like there could be a tacho device connected to (at least some of) the remaining wires (blu/grn red/blk). This would provide feedback input for the motor-drive unit, which I'm guessing is at least part of the pcb. Not sure what the xfms would be doing though, maybe isolating the machine from the rest of the airplane electrics? Could it have recieved some kind of stop-go signal from the airplane via those? or maybe it's all not related. Just speculating.
A schematic reverse-engineering would be the next logical step.

Or if we're out in the bush with a screwdriver and a pair of children's scissors, put some power on some of the pins in the connector, looking at the caps would give you an idea of polarity.
Find an old cassettedeck or scrapped mono reel-to-reel and wire up the heads to it, it will likely make sound, though the quality will depend how lucky you get with impedance and level matching.
I have a old Philips tube mono r2r you can have, but it's a bit heavy to send;-)
Have fun tinkering!
 

ion

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you mean transplant the heads to another recorder?
i would totaly lose the cool nagra sn tiny size.

the multi color wires are from the playhead

the black wire goes to a Terminal connection (the E‘s) and seems to be chasis ground.
 

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