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Feb 22, 2016, 01:10 PM
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rcyard's Avatar
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Help!

Reverse engineering and repair of a vintage Metz Mecatron single channel radio


I would like to connect a Metz Mecatron receiver to a Graupner Kinematic actuator. The Mecatron receiver has an old-style 7 pin connector. I'm out of luck to find out each pin's function. I appreciate any help.
Last edited by rcyard; Jul 14, 2016 at 05:48 PM.
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Feb 22, 2016, 01:32 PM
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Does this link help at all?

https://www.rcgroups.com/forums/show...2#post24898588

or this one:

https://www.rcgroups.com/forums/show...226288&page=33

and, of course, these people will help... http://www.singlechannel.co.uk
Last edited by dodgy; Feb 22, 2016 at 01:42 PM.
Feb 22, 2016, 01:38 PM
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I checked the first topic you mentioned and the 'Radiostyrning av modeler' book mentioned in that topic but it didn't help me out with the pinout.

I found a wiring of a Metz servo in the book, but this doesn't help me out.

I don't find anything useful in the second forum topic.
Last edited by rcyard; Feb 22, 2016 at 01:53 PM.
Feb 22, 2016, 02:50 PM
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Did you look at the images? These are circuit diagrams for the various Metz items of equipment.

The first link show the circuit diagram for the 'Baby Metz' receiver, which is yours. I'm a little confused at the circuit - I can't tell whether the top line is negative or positive. If you have the receiver you may be able to tell - otherwise talk to singlechannel.co.uk.

My reading of the pins is:

Pin 1 - +6v or ground
Pin 2 - Normally closed switch output
Pin 3 - Normally open switch output
Pin 4 - Switch input
Pin 6 - ground or +6v

and you should be able to test whether pins 2/3/4 perform as above with a multi-meter...
Feb 22, 2016, 06:17 PM
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Quote:
Originally Posted by dodgy
Pin 1 - +6v or ground
Pin 2 - Normally closed switch output
Pin 3 - Normally open switch output
Pin 4 - Switch input
Pin 6 - ground or +6v
Thank you, Dodgy. I asked an electrician about the positive and negative pins and he told that Pin 1 is positive.

So I think I have to wire up like this:
Pin 1: +6V
Pin 3: Kinematic upper right connector (+)
Pin 4: +3-4.5V
Pin 6: 6V ground

The receiver should short circuit Pin 3-4 when there is a signal.

Furthermore, I have to give 3-4.5V ground to the Kinematic upper left connector, and voltage to the motor (this will be 6V) with the help of the Kinematic lower 4 connectors.

It looks I don't need Pin 2, this would work just the opposite as Pin 3. I don't know what it is good for, maybe with some other actuators it is needed.

I will wire it up like this and report back what happens
Feb 23, 2016, 04:11 AM
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That is the usual interpretation - but looking at the circuit I thought that some electrolytic capacitors would be held in reverse polarity if the top line were positive....

However, we agree that power goes between 1 and 6. You then have a radio-controlled switch, with the input (4.5v, as you say) on pin 4. This switch is normally switched to pin 2, but when it gets a signal it switches to pin 3.

Good Luck!
Feb 23, 2016, 10:47 AM
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Let's check if we see the same diagram. On my diagram the top line is pin 6, not pin 1. Pins are numbered from the bottom to the top in this diagram.
Feb 24, 2016, 02:37 AM
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Yes, that is the same diagram.

Traditionally, on circuit diagrams the top line is positive and the lower line is ground, but I thought that some of the components would be connected incorrectly if that were the case, so I wasn't sure. That was why I suggested that you talk to singlechannel.co.uk, or to another specialist....
Feb 24, 2016, 03:47 AM
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Quote:
Originally Posted by dodgy
Yes, that is the same diagram.

Traditionally, on circuit diagrams the top line is positive and the lower line is ground, but I thought that some of the components would be connected incorrectly if that were the case, so I wasn't sure. That was why I suggested that you talk to singlechannel.co.uk, or to another specialist....
AM I TOO LATE?????

In the past the radio systems were equipped with (PNP) germanium transistors, no silicium, the line on top of the diagram has to be connected with the minus of the battery. Bottom line is positieve.


For germanium transistors of the early days the PNP configuration was commonly used, later for silicon transistors the NPN. The way of drawing the circuit diagrams stayed the same only the supply polarity was changed.

The numbers are printed on the connector. The 'normally closed ' contact of the relay can be measured to check, 0 ohm between 2 and 4. When the channel is actuated the 0 ohm can be measured between 3 and 4. (Or visa versa when the circuit is written in a relay-actuated situation but I don't think so. The contact of the relay is a little bit mirror imaged than we normally show )

I did use the Metz actuators in the past, single and two channel (see the drawing of one of the earlier posts, I still do own such a two channel actuator and design and make superregen radio's with the original vintage germanium transistors, see the picture).

Cees
Last edited by Taurus Flyer; Feb 24, 2016 at 05:54 AM.
Feb 24, 2016, 11:16 AM
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Quote:
Originally Posted by Taurus Flyer
AM I TOO LATE?????
.......
For germanium transistors of the early days the PNP configuration was commonly used, later for silicon transistors the NPN. The way of drawing the circuit diagrams stayed the same only the supply polarity was changed.

......

Cees
Ah, that explains it. By the time I was brought up, circuits had a top line positive.

However, you will see that I noticed that that would result in odd connections, so I carefully did not say that pin 1 WAS positive - I said that rcyard should check - ideally with singlechannel.co.uk, who are skilled in early R/C, or some other specialist. I'm glad to see that we have found one...
Feb 24, 2016, 06:18 PM
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Quote:
Originally Posted by Taurus Flyer
In the past the radio systems were equipped with (PNP) germanium transistors, no silicium, the line on top of the diagram has to be connected with the minus of the battery. Bottom line is positieve.[/B]
Thank you for the explanation. I wired up the Mecatron receiver accordingly (pin 1 positive, pin 6 ground). The receiver seems to be working, I see the relay switching when it gets power.

I could figure out the original Metz wires coloring as well. I include it here, someone may consider it useful:
Pin 1: brown (positive)
Pin 2: white
Pin 3: blue
Pin 4: yellow
Pin 5: green
Pin 6: red (ground)
Pin 7: black

The relay is switching between yellow-white and yellow-blue.
Green and black is unused with this 'baby' receiver.

However I still have a problem. It seems that my transmitter is not working so I'm unable to use the system. I disassembled the transmitter and I see one component is broken. I don't have an idea what it is so I took a photo of it. Does anyone know?
Feb 24, 2016, 06:32 PM
I bail out, anywhere, anytime
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rc

That's a capacitor, What kind of model transmitter is it?
Show me a picture of the outside, than I will look in the circuit diagram.
Maybe the value of this capacitor is writting on it in black paint, maybe on the backside. Value is given in pF (picofarad). The purple dot is an indication of the temperature coŽfficiŽnt.

Cees
Last edited by Taurus Flyer; Feb 24, 2016 at 06:57 PM.
Feb 24, 2016, 07:02 PM
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Quote:
Originally Posted by Taurus Flyer
That's a capacitor, What kind of model transmitter is it?
Show me a picture of the outside, than I will look in the circuit diagram.
The transmitter is a Metz Mecatron 190/1. It is exactly this type:
http://www.radiomuseum.org/r/metz_mecatron_1901.html

I have a circuit diagram, but this is for a slightly different transmitter, it has a switch on the top, I have a rotary power switch in the back.
Last edited by rcyard; Feb 25, 2016 at 03:48 AM.
Feb 25, 2016, 03:47 AM
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I found another schematics in the 'Radiostyrning av modeller' book: http://modellflygnytt.se/gamla/19xx/...v_modeller.pdf (page 23). This radio rather seems as my radio, but it has a bigger button on the top. Otherwise it seems to be the same.

Here is the circuit diagram.
Feb 25, 2016, 04:19 AM
I bail out, anywhere, anytime
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rc

The circuit diagram of latest post you showed can be the right one but it isn't all clear yet.
There is one capacitor that can be your defective, the 6 pF capacitor, see the red circle but the coil has to have two more connections for that, see the red arrow and two dashes.

Can you make a overview and some detail photographs of the inside and showing details of the connections of the tube/valve.

Cees


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