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Multiplex Help!


Stuphedd
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I became the custodian of a very old Multiplex Royal MC Soft modul set recently that I require some help with !

It has to be old as the RXes are 4 pin ! It also has more knobs whistles switches plug in modules that the ISS!

Problems

No manual , and I cannot find a down load on the net

The TX came in kit form !!

and obviously no info

The reason for the Kit TX , is that I have deduced it was stored with batteries and so black wire syndrome is evident . However I mechanically put it together , direct wired a battery 9.8 volts , hope thats OK, and the PC board has a BATTERY point written on it !! , fired it up , linked it to a JR synth RX and it works !!

So what I need to know , is how is the TX charged ? and why are there 4 wires that appear to be battery oriented ?? all 4 have been cut due to black wire corrosion

Any body out there with any experience of this set ??

cheers

Pete W.

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The multiplex-RC.de archive has a copy of a manual in German that might help:-

Manual

The link in full is:-

https://www.multiplex-rc.de/Downloads/Multiplex/Archiv/bedienungsanleitung-royal-mc--de.pdf

It seems to have 4 pin servo leads so might be of a similar vintage if not actually the correct model.

Dick

Edited By Dickw on 20/11/2017 10:23:58

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Pete: I've no direct experience with the Tx you have, but I did have a Multiplex UHF set for many years. That Tx - and other MultiplexesI have seen - used 6-cell packs (7.2V), rather than the more usual 8-cells (9.8V). The extra voltage will probably do the encoder no harm, but I wouldn't run it with the Tx aerial collapsed for long, or you may blow the output transistor.

I'm sure someone will be along shortly to confirm whether your Tx is 6-cell or not!

For many years, servos used a 4-wire connection. The extra wire was a centre tap on the battery. The receiver ran off the usual 4.8 volts, but the servo motors ran off 2.4 volts. One side of the servo motor was connected to the centre tap, and the other switched between either the positive or negative of the battery to drive it one way or the other.

When integrated circuit amplifiers became the norm, these were designed with a "bridge" output, eliminating the need for a centre tap, but requiring 4.8V motors instead of the earlier 2.4V type.

To get your 4-wire servos working, you will need to add a centre tap connection to a standard 4-cell pack.The pinouts are usually the signal pin being out on its own, and the other three being the battery +ve, centre tap and -ve. The centre tap is usually the middle pin. You will need to work out which is +ve and which is -ve!

Best of luck!

--

(Another) Pete

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I own a Multiplex Royal MC transmitter bought in 1985 from Harry Brooks at the Nationals. A friend also had one and gave it to me so I now have two Mpx Royal MC transmitters.

I still use Multiplex radio, but no longer this gear!

To answer your questions:

The transmitter had 2 6 cell 7.2V nicad batteries hence the 4 wires. They were wired through a latched switch so you could change over battery if one ran low. The current NiMh 7.2V Multiplex transmitter batteries fit. There are Enelope equivalent batteries also available fitted with the same plug.

The radio is later vintage than the era of 4 wire servos. However, the traditional Multiplex plugs were 4-way, but only 3 pins were used.

The radio was well ahead of its time - only Simprop came close.

If you have any more questions don't hesitate to ask.

Robert

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You guys are brilliant !

Nearly all my questions have now been answered so thanks very much smiley

I have 2off 7.2 packs , they are now on charge via another charging system , SO One last question for the time being

presumably the TX batteries are charged via the plug on the front ?? which I have , but what power source do you charge it from ?? ( can I say any old 100ma system for a 7.2 stack ??)

Thanks

Pete

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Pete,

I think I charged it at 100mAH with the latch switch in the centre position, so both batteries were charged together.

The mixing capability of this transmitter was well ahead of its time. As you know the transmitter is configured via a Soft Modul for F3A, F3B, Heli etc. The values were changed in hardware via pre-sets. Some Soft Moduls had memories and thus they stored these values. Powerful stuff for mid-80s. Even now some non-European radios have less flexibility ...

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Thanks for all the help ,

I have now got it working , on 4 of the channels anyway , and got rid of the considerable amount of mixing ,

it came with both PPM and PCM,RXes and they all work , when you find the PPM/PCM switch , There were no servos so I "slaved " some to test it out and alls well ,

For its day it must have been expensive !!?? Nicely put together compared to todays plastic !

Whether I will ever use it in reality is another question , but as a learning curve its been "good fun"

thanks again

Pete

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