Author Topic: Identify giant transformer from 1978 tape reel  (Read 5118 times)

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Offline MarkF

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Re: Identify giant transformer from 1978 tape reel
« Reply #25 on: May 04, 2019, 08:16:43 pm »
Getting closer.  Only missing brown wire.
https://elektrotanya.com/pioneer_rt-701_rt-707_art2540_additional.pdf/download.html#dl

   

Given that electrotanya schematic, my guess would be that the brown wire might be the 120V primary tap - check to see if it has continuity with the black, violet and grey wires.  If that is correct, the resistance between the black and grey will be highest, black and violet less, and black and brow the least of the three.

-Pat

Yes.  I totally misread the voltages on this last diagram.
I believe this is what the transformer looks like.
However, the first diagram shows the red winding as 1A and the second diagram show it as 630mA.

Checking the resistance between the four primary wires should verify this.

   
« Last Edit: May 04, 2019, 08:24:53 pm by MarkF »
 

Offline Jwillis

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Re: Identify giant transformer from 1978 tape reel
« Reply #26 on: May 04, 2019, 09:29:28 pm »
That model RT-701 had several versions.

    RT-701/KU = #3603301~     (Canada/USA) 120V
    RT-701/KC = #3400001~     (Canada/USA) 120V
    RT-707/KU = #3606301~     (Canada/USA)  120V
    RT-707/KC = #3400001~     (Canada/USA) 120V
    RT-707/D  = #9301201~      (US Military) Various
    RT-707/DG = #9301001~    (General Export) various
    RT-707/HG = #8400001~    (Europe/Oceania, Scandinavia, UK)  220 - 240 V
 
This would explain the different primary configurations of the transformer.   

 The second number would be the beginning of the serial number probably on the back somewhere.
 

Offline queennikki1972Topic starter

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Re: Identify giant transformer from 1978 tape reel
« Reply #27 on: May 04, 2019, 10:32:32 pm »
The Brown wire does in fact have continuity with violet black and gray
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Offline queennikki1972Topic starter

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Re: Identify giant transformer from 1978 tape reel
« Reply #28 on: May 04, 2019, 10:38:16 pm »
Brown to gray 6.8 ohms
Back to gray 10.3 0hms
Black to violet 10.3 ohms
brown to violet 5.7 ohms
brown to black 3.7 ohms
Siglent SDS 1202X-E - Heathkit IO-4105 - Dr. Meter 0-30v 5a power supply - 862d+ combo unit - Weller WLC100 - Kunkin KL283 DC load. Not much gear yet.
 

Offline queennikki1972Topic starter

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Re: Identify giant transformer from 1978 tape reel
« Reply #29 on: May 04, 2019, 10:40:10 pm »
I would have thought such a huge transformer would have been more amps ?? But the voltages are very high
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Offline queennikki1972Topic starter

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Re: Identify giant transformer from 1978 tape reel
« Reply #30 on: May 04, 2019, 10:49:51 pm »
MarkF you have voltage for the 2 green wires on the secondary side but on the transformer they are on the primary side. They do not have any continuity to the other primary wires.
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Offline Jwillis

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Re: Identify giant transformer from 1978 tape reel
« Reply #31 on: May 04, 2019, 10:52:41 pm »
The size requirement of the core is dependent on the total current draw on all secondaries .so if you take the example by cubdriver .you add the current of all secondaries which is 6.5 amps so hence the large core area.Of course that's very simplified because each secondary carries a different voltage
As stated before secondaries can appear on the primary side simply for convenience of winding the bobbin .
« Last Edit: May 04, 2019, 11:21:11 pm by Jwillis »
 

Offline queennikki1972Topic starter

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Re: Identify giant transformer from 1978 tape reel
« Reply #32 on: May 04, 2019, 11:19:36 pm »
Im sorry I missed what you said about the green secondary wires on primary side in your earlier post.
Siglent SDS 1202X-E - Heathkit IO-4105 - Dr. Meter 0-30v 5a power supply - 862d+ combo unit - Weller WLC100 - Kunkin KL283 DC load. Not much gear yet.
 

Offline MarkF

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Re: Identify giant transformer from 1978 tape reel
« Reply #33 on: May 05, 2019, 02:13:03 am »
MarkF you have voltage for the 2 green wires on the secondary side but on the transformer they are on the primary side. They do not have any continuity to the other primary wires.

The physical side the wires come out of the transformer is irrelevant to whether it is a primary or secondary winding. 
Look at a toroidal transformer for instance.  Most of the time all the wires come out at the same place.


Brown to gray 6.8 ohms
Black to gray 10.3 ohms
Black to violet 10.3 ohms
Brown to violet 5.7 ohms
Brown to black 3.7 ohms
BLK-BRN(3.7) + BRN-VLT(5.7) = 9.4   ?   BLK-VLT = 10.3

According to your numbers, I think the transformer windings are like this.
It seems a little funny where the 120V tap is.  Maybe that makes a wiring connection that is simpler.

   
 

Offline Cubdriver

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Re: Identify giant transformer from 1978 tape reel
« Reply #34 on: May 05, 2019, 02:17:13 am »
Another thing to keep in mind about transformers is that they transform voltages and currents, but power (voltage multiplied by current) stays the same (less some relatively small losses; nothing is perfect). 

As a simple example, if you have a step up transformer that has a 10:1 secondary to primary ratio, it will put out 10x the input voltage.  Put 120 in, you'll get 1200 out.  You'll also get 1/10 of the current that flows in the primary - if you pull 100mA (0.1A) from the secondary, there will be 1A flowing in the primary (ignoring losses).  This would be considered to be a 120W transformer.  Conversely, if the ratio is opposite with 1 turn on the secondary for every ten on the primary, the output voltage would be 1/10 that of the input (12V), but for that same 1A primary current, you would draw 10 amps.  It would still be considered a 120W transformer, and would be about the same size as the previously mentioned step-up unit mentioned earlier.

Other than for transformers at the extremes (insanely high voltage or insanely low current, either of which might require specialized construction due to the need for insulation in the HV case, or very heavy wire in the LV, high current case), you'll find that transformers of a given power handling capacity are generally about the same physical size.  Power capacity can be determined (if the secondary voltages and currents are listed) as someone mentioned above by multiplying each voltage by the associated current to get the power, then adding the power values to get the total.  In short, just looking at a transformer usually won't tell you much about its input or output voltages, but will give you a feel for how much power it can pass.

I hope this makes sense rather than muddying the waters for you.

-Pat
If it jams, force it.  If it breaks, you needed a new one anyway...
 

Offline MarkF

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Re: Identify giant transformer from 1978 tape reel
« Reply #35 on: May 05, 2019, 05:34:51 am »
Im sorry I missed what you said about the green secondary wires on primary side in your earlier post.

I don't know what you are referring to?
 

Offline soldar

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Re: Identify giant transformer from 1978 tape reel
« Reply #36 on: May 05, 2019, 08:00:10 am »
According to your numbers, I think the transformer windings are like this.
It seems a little funny where the 120V tap is.  Maybe that makes a wiring connection that is simpler.
What if you look at it like this:

There is a good chance the two 120 V sections are of different wire thickness and resistance and the lower resistance winding should be used. BLK seems to be the common for all voltages and BRN for 120 V. Resistance measurements confirm this.
« Last Edit: May 05, 2019, 08:33:17 am by soldar »
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Offline MarkF

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Re: Identify giant transformer from 1978 tape reel
« Reply #37 on: May 05, 2019, 10:29:09 am »
According to your numbers, I think the transformer windings are like this.
It seems a little funny where the 120V tap is.  Maybe that makes a wiring connection that is simpler.
What if you look at it like this:

There is a good chance the two 120 V sections are of different wire thickness and resistance and the lower resistance winding should be used. BLK seems to be the common for all voltages and BRN for 120 V. Resistance measurements confirm this.

If the BLK to BRN winding has a heavier gauge wire, why are they using the BRN to GRY winding for the 120V input which would require more current?

In the circuit diagrams, the 120V input has a 2A fuse while the 240V and 220V inputs have a 1A fuse.
 

Offline soldar

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Re: Identify giant transformer from 1978 tape reel
« Reply #38 on: May 05, 2019, 10:44:00 am »
If the BLK to BRN winding has a heavier gauge wire, why are they using the BRN to GRY winding for the 120V input which would require more current?

In the circuit diagrams, the 120V input has a 2A fuse while the 240V and 220V inputs have a 1A fuse.
Where can I see the schematic?
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Offline MarkF

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Re: Identify giant transformer from 1978 tape reel
« Reply #39 on: May 05, 2019, 11:16:29 am »
There are two links above (copied here):
   https://www.esotericsound.com/SalesImages/rt-707sm.pdf
and
   https://elektrotanya.com/pioneer_rt-701_rt-707_art2540_additional.pdf/download.html#dl

You can also look at screen captures I posted earlier in this thread if you don't want to search the documents (Reply #19 and #20).


Edit:  The 120V transformer in the circuit diagram is a RTT-116.  I can't find the part no. for the 240V/220V transformer.
         The transformer she has is a RTT-118.
« Last Edit: May 05, 2019, 12:15:30 pm by MarkF »
 

Offline MarkF

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Re: Identify giant transformer from 1978 tape reel
« Reply #40 on: May 05, 2019, 12:42:01 pm »
I found a RTT-116 transformer on eBay.  It only has one primary winding.
So, we can not use it as a wire color reference.

I am beginning to think @soldar is right...
   BLK and BRN for 120V
   BLK and VLT for 220V
   BLK and GRY for 240V
 
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Offline 6PTsocket

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Re: Identify giant transformer from 1978 tape reel
« Reply #41 on: May 07, 2019, 12:57:58 am »
Close.  Hers has two extra wires (purple and black).
Maybe two primaries for 120V or 240V operation?
pg.59 says power transformer part no. RTT-115

   

   
The AC line in Japan is 100 volts so one extra primary tap might be for that. I recall Japanese hi fi equipment that had a 100 volt tap for domestic consumption

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Offline MarkF

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Re: Identify giant transformer from 1978 tape reel
« Reply #42 on: May 07, 2019, 01:39:38 am »
Thanks. 
I thought there was another standard voltage that I've seen as selectable on some equipment.   
(i.e.  100VAC / 120VAC / 220VAC / 240VAC)
« Last Edit: May 07, 2019, 03:04:58 am by MarkF »
 
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Offline schmitt trigger

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Re: Identify giant transformer from 1978 tape reel
« Reply #43 on: May 07, 2019, 02:31:07 am »
You are correct.
100 VAC is the household voltage in Japan.
 
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Offline MarkF

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Re: Identify giant transformer from 1978 tape reel
« Reply #44 on: May 08, 2019, 09:29:37 am »
A little bored.  So, I thought I would summarize our findings.
It hasn't been obvious but the BLU to YEL winding could be used for another 30VAC.

   
« Last Edit: May 08, 2019, 01:15:16 pm by MarkF »
 
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Offline Richard Crowley

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Re: Identify giant transformer from 1978 tape reel
« Reply #45 on: May 08, 2019, 06:59:53 pm »
And Violet to Brown for 100V mains input?  (Japan)
Assuming the wire gauge supports the current required.
 
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