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Old 24th Mar 2017, 2:07 pm   #1
Tractorfan
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Smile RTTY to TV convertor.

Hi,
I'm in the process of getting back into amateur radio and I've unearthed this Microwave Modules RTTY to TV converter model MM2001 that I've had for years.
Quite naturally, of all the various power leads & DIN connectors I've accumulated in a box, guess which one I can't find?
This unit works on 12 volts and the power connector is a 270 degree DIN plug. Could some kind soul out there please tell me which pins I need to wire up?
Many thanks in advance.
Cheers, Pete.
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Old 24th Mar 2017, 2:31 pm   #2
dragonser
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Default Re: RTTY to TV convertor.

Hi,
that looks like an interesting unit. if you could take a photo of the inside of the unit then that would hopefully provide more clues !
Peter B
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Old 24th Mar 2017, 7:05 pm   #3
Tractorfan
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Smile Re: RTTY to TV convertor.

Hi,
I had a squint inside, but the top PCB obscures a good look at the connectors. I tried removing it, but the 25 pin socket soldered to said PCB won't give up its fixing screws.
Cheers, Pete.
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Old 24th Mar 2017, 7:31 pm   #4
TonyDuell
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Default Re: RTTY to TV convertor.

Maybe you can work it out....

Is that little 3pin Molex KK socket plugged onto the pins of a 3 terminal regulator in a TO220 case? It lools like it to me. Since the only connection to the middle pin is the ceramic capacitor, I am guessing it's a 7805 regulator, tab (common) grounded to the case). In which case the red wire on that socket is the 5V line, the purple one, the unregulated input.


There is an EPROM on the PCB that you can see. Pin 12 (bottom right in the photo) is going to be ground. Does that test short-circuit to the case? Does it test short-circuit to any of the pins on the power connector? If so, that's the -ve side of the supply.

Now with any power switches on the unit 'on', test from that red wire to pin 24 on the EPROM. Dead short?

Does the purple wire from that connector/regulator go to the power socket? If so, that pin is the +ve input.

I am assuming, as you imply, it's just a single 12V supply that it needs.
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Old 25th Mar 2017, 10:45 pm   #5
Tractorfan
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Smile Re: RTTY to TV convertor.

Hi,
Thanks for your tips Tony. However, the purple wire from the regulator doesn't go directly to the power socket but disappears into the hidden depths (there's no on/off switch).
Eventually I found the correct pins and the unit now works, apart from a snag with the audio input. But that's another story.
The connections turned out to be:
Negative to pin 3.
Positive to both pins 4 & 5.
(looking at the solder side of the plug.
Cheers, Pete.
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Old 26th Mar 2017, 6:59 pm   #6
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Smile Re: RTTY to TV convertor.

Hi,
Further to my post yesterday, I made a mistake re: wiring the power plug.
The positive wire goes ONLY to pin 5 and is NOT connected to pin 4 as well.
I had all sorts of fun and games wondering why the unit went dead upon connecting the audio input. Doh!
Cheers, Pete,
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