Dukane content

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Big thanks to Mick for encouraging me (almost a year ago) to try and get something out of this ancient artifact 

I wanted to put on my big ugly dim bulb tester but was kinda perplexed by the results.

60w bulb unscrewed and 43w bulb screwed in
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Now 60w bulb screwed in and 43w bulb unscrewed
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And both screwed in
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I didn't know if this was good or bad...they both glowed but more pink and orange not like a bright light.

So I figured ok might as well try something but maybe it's got blown outputs (?)

I grabbed a speaker and not having the slightest idea where to attach I picked two terminals and attached them and when I plugged it back in I was stunned to hear some noise 

I grabbed my cable to attach a signal and I can't believe it works           

But when I increased signal output it got really ugly sounding like it was in a blender 

So I removed some jumpers that had been there probably forty or fifty years and tried it again this time nice and clean 

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Also I saw the bulb would get brighter when I increased signal 🚦

If you are wondering there are no controls or power switch. 

It came with another piece that had knobs and level controls and one medium sized speaker.

Btw attached to the power cord were a couple of tags like instructions how to attach speakers
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So wow I'm really glad that I tried it and got sound thanks again Mick 

If I can get it set up to listen to ball games from a tuner or maybe even some music man that would be awesome 

Hey guys do you think that is a transformer and a choke or two transformers 

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View from the top
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Here is the front of the amp...no controls switches or anything
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And here is the "controller" 
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Rear
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Lots of terminals
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The speaker has some multi tab transformers
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And all put back in their home for now
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So now I have a purpose in life

Find out how to connect a pair of normal 8ohm speakers and a tuner to the controller via the level control 
Then connect that to the amp or vice versa
The controller also has a power switch on the front so I have to find out how to connect the mains

Shouldnt be too bad compared to trying to install in a university auditorium 

[Miyagi_83]

Hey guys do you think that is a transformer and a choke or two transformers 

As a wild guess, the one closer to the power cord is most probably the power transformer. The other one could be a choke, an output transformer, a line transformer or something else. I would take a look inside to see what each one is connected to. With the mains unplugged and caps discharged of course. (Hope I didn't come off as condescending or anything).

EDIT: I did a quick search for this model's circuit diagram, but couldn't find anything. Either nobody uploaded it or it's unavailable in my location.

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Thank you sir 

After scouring the interwebz for a while it seems the 25v configuration wasnt really designed for 8 ohm aka "normal speakers" but will suffice.  And I think that's what Mick was talking about eleven months ago. 

Causing further complications is well two eight ohm speakers in parallel....

Also I guess obviously it's gonna be mono...I get it it's not a Pioneer or Marantz..but I'm befuddled about why each "monitor selector" has eight positions but there are only four positions on the back.

When I get time I will do some continuity tests on the controller unit and propose some possible configuration(s).

When I ran signal into it I was able to control the level....had I just connected a tuner to it I wonder how loud it would have been 

I guess that I need to jumper 1-3-5 and connect neg or pos from two speakers then jumper 2-4-6 and connect other two POS or neg then each one of those speaker wires out goes to a "level" control 

Also with the 25v configuration using 1-3-5 and 2-4-6....what's up with 7 and 8 

Might have to get some voltage readings.

The multimeter is the most important piece of equipment 

[Tassieviking]

From memory I found a connection diagram for that PA system, PA systems do not use a speaker output but they use a voltage output that feeds into a transformer at each speaker.
It is done that way so you can have really long cable runs with less losses at the speakers.
If you look for audio transformers you will find the correct type of transformers to use since they are rated at 100V, 70V, etc on the input and the output is rated at watts (usually for an 8 ohm speaker)
I have 2 small transformers like that that I can use as an output transformer in a 1-2 watt tube amp, even though they are not meant for that.
Here is a link to the ones Mouser have for sale:

https://au.mouser.com/c/power/transformers/audio-signal-transformers/?m=Visaton&secondary%20impedance=4%20Ohms~~8%20Ohms%2C%204%20Ohms&rp=power%2Ftransformers%2Faudio-signal-transformers%7C~Secondary%20Impedance

The selector switch is most likely so they could send the sound to the right department, office, workshop, dispatch canteen etc.
they could also select the different wattage taps on the speaker transformers so it suited that area, I imagine the office would be less noisy then the workshop floor.

I think they could have used that unit almost anywhere since they were/are common in factories, shopping centres, train stations, clubs, and many more places.

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Thank you sir 

This is gonna be good I can learn something  because right now it's blowing my mind. 


So maybe I'm not jumping or configuring for 25 or 70v but rather connecting to the speaker terminals as is...

Also is there a correct term for this device (unless mother ship 🚢 is good 👍)

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Is it possibly called a "transport" ?

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I think I made a monumental discovery today



(Possible) Monumental discovery below:







I think I am missing and or need a preamp


 

[Jazz P Bass]

As far as I can tell that unit is a 'Constant-Voltage' amplifier.
ie: A Public Address amplifier.
Yes, it needs a preamp of sorts.

[Tassieviking]

If you look at the speaker in the other unit you will see it has 2 output transformers that is the type you need to drive 8 ohm speakers with the amp.
I am guessing that the speaker might have 2 voice coils or something to be needing 2 transformers.
Take a good look at those transformers and see if you can work out the input voltage, then you can use them to drive 2 separate 8 ohm speakers.

[Tassieviking]

I found the post from December last year, I wrote this:

"I looked around at some Dukane amps and it seems some of them you could link terminal 1-3-5 and 2-4-6 and then you have the output for 8 ohm speakers.
I think they had 3 different coils that ran at 25 volt output, possibly 1-2, 3-4, 5-6 were the separate coils.
When you run them in parallel like I said above they became right for 8 ohm.
If you run them in series they form a 75 volt (70volt) output for PA speakers.

I think I can see a link between terminal 1-3-5 on your photo so it was running an 8 ohm speaker, there will be links between 2-4-6 as well.

Plug it in and see if you hear anything"

You should be able to check with a multimeter if you have 3 output coils on the back of those terminals.
Check for resistance between terminals 1-2, 3-4, 5-6.

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Yes sir thanks to all I plan to do all of that and I thank you for letting me enjoy the journey  one step at a time

 

I don't want to bombard everybody with questions but I was looking at something old to pair it up with...I saw many "🎤 microphone 🎙� preamps looks like they have weird input connectors i don't think a mic preamp would work ?

Also those level controls on the mother ship did they run the speaker out through those to control volume ?

But anyway thanks my task at hand is measuring voltages on 1-2 3-4 5-6 7-8

 

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Ok I got some (crappy) voltage readings

I'm thinking most of this data is nonsense because (insert technical reason here: "second transformer needs current draw to turn on etc")

In summary voltages were all over the place under 10v I attempted to stabilize them by putting a 5.5M ohm resistor (then 10 ohm) across the terminals but didnt help.
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As a final hail Mary I jumpered 1-3-5 and 2-4-6 and got more nonsense....so idk 

See some junk science tabulated here :

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Values were tough to approximate the readout really wouldn't stay put 

And now looking at the picture apparently I have a green-blue-green resistor

 

[Tassieviking]

I think we will try this again.
Turn the amp off and unplug from power point.
Measure resistance between terminal 1 to 2
Measure resistance between terminal 3 to 4
Measure resistance between terminal 5 to 6.

We need to know if those are the 3 output windings on the output transformer.
You should have very low ohm readings on those terminals.
If the readings are very close to each other then it is likely you have 3x 25V output windings, I have seen that setup on other Dukane amps.

Join terminals 1, 2, 3 together
Join terminals 2, 4, 6 together
Connect an 8 ohm speaker to terminal 1 and terminal 2.
turn on and put a signal into the amp.

Here is the picture you posted last year when you first got that amp, you can clearly see that 2,4,6 are linked and 1,3,5 are linked.
There is also a wire connected as if it is going to a speaker in the picture.
If you right click and save the picture or open in new tab you can see better.