Author Topic: Different Revision MP-2 RF Modulator - Help Composite modding  (Read 4085 times)

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Offline a7mag3ddon

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Hi All Total noob to Amstrad's here so please go easy, and this is my first post.

Ok so im looking for some help composite modding my MP-2 RF Modulator so stumbled across this site, however when i looked at the diagrams you have on here they are quite a bit different to mine.

I then spent some time looking at the board and saw the RGB encoder chip was the same (MC1377P) so got a datasheet for it, i have tried to mod it based on the datasheet where pin 7 is video clamp and pin 9 is the composite video out but 2 things happened, when i went from 1 side of the cap (closest to pin 5) the screen was black and white and rolling and when i go the other side of the capacitor (ground side) the screen is ok and in colour but the text seems slightly blurred (to me)

Could some one take a look at the following pictures and see where i went wrong? Thanks.

MP2 cover



MP2 Rear Label



MP2 Circuit Board




My MP2 Mod Wiring

The solder point bottom left is coming from pin 9 and the top most solder point is the capacitor leg on the ground side from pin 7



The Resulting output (looks worse on TV)






« Last Edit: 02:16, 30 April 15 by a7mag3ddon »

Offline TFM

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If you don't own the original monitor then imho best is to make an RGB to SCART cable. That provides the best quality. See CPCWiki for page how to do it.  :)


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Offline Bryce

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Hi and welcome to the forum,
        I'm afraid that the blurred colour picture is the correct connection points and about the best you'll get from 80's Composite on a TV that big. The upscaling and conversion makes things look a lot worse than on a small screen. It can be slightly improved by tweaking the circuit with a few capacitors, but as TFM said, an RGB SCART will give you a better picture, or an RGB to S-Video adapter if your TV doesn't have SCART.

Bryce.

Offline roy bates

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it might sound daft,but cant you get chroma and luma out of these?

i would rather go for rgb myself,but i am wondering

Offline a7mag3ddon

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Yeah i could use RGB scart. I could take the din of the MP2 and wire it into a scart socket.

Offline Bryce

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Seperated Chroma and Luma is S-Video. The MC1377 doesn't offer that, but the AD724 which this is based on does: RGB SVideo - CPCWiki

Bryce.

Offline a7mag3ddon

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If i wanted RGB to scart would I get that from the video din on the 6128 or the mp2?
« Last Edit: 13:46, 30 April 15 by a7mag3ddon »

Offline Bryce

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Directly from the Monitor port on the back of the CPC.

Bryce.

Offline a7mag3ddon

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I now need advice on the tape port should I start a new thread?

Offline Bryce

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Na, not really, what's the question?

Bryce.

Offline a7mag3ddon

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I want to load tape based games from my phone as I do with my 464 however I soldered my audio jack to the tape head points on the PCB.  Obviously not available on 6128 so looked at the tape socked and pushed wires into gnd and data in but didn't work.

I have seen on Retroshack tape cables with rem/ear/ mic so assuming it can be done.

So question 1 can I wire a socket myself or question 2 if I buy the premade cable can I just push the jack plug into the phone?

Offline Bryce

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Ok, generally what you did was correct but the levels will be wrong. The signals at the tape head go through an amplifier before they make it to the "data-in" point, so the volume on your phone probably only needed to be very low to work. Technically, the data-in point will work, but the volume on your phone will have to be much higher to get the levels right (some phones may not be able to deliver enough power for this).
As well as that, pushing loose wires into an old oxidised socket isn't exactly what I'd call a "robust connection". Buy one of the correct leads and try that.

Bryce.

Offline a7mag3ddon

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Haha understood ref the wires. It was late in the night and I has already stripped and rebuilt the floppy drive and didn't want to take it apart again just to test my theory ;-) I'll solder the wires direct to the pins instead and try again. I do have a separate tape deck I could try.
« Last Edit: 15:42, 30 April 15 by a7mag3ddon »

Offline a7mag3ddon

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I think tonight I will test the theory out by wiring a socket direct then plugging in my speccy tape deck with a mp3 cassette adapter to my phone. Long winded but if it works I could then add a audio booster internally.

Is the tape sense needed at all?

Offline Bryce

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Tape sense? You mean the "Remote" pin?

Bryce.

Offline a7mag3ddon

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Yeah remote. Doesn't it allow the deck to stop and start? Is it needed to play audio into the socket. C64 is a required connection.

Offline Bryce

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No. On the CPC it can be ignored. It's useful for real tapes when they have multi-load or need a delay before continuing to read data, but otherwise not.

Bryce.

Offline a7mag3ddon

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Got it working a treat loaded a couple of games direct from phone, wasn't expecting it to work. Gotta say the composite out is really ropey. Colour shifting is terrible. Ordered an RGB cable sadley retro shack didn't do them so god knows when it will arrive. 

Offline a7mag3ddon

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Scratch that the composite out is really bad, loaded rainbow island and I thought oooh what a cool scrolling rainbow effect they did on through the loading screen. However turns out it was all in the game as well. LoL ordered a RGB scart lead last night ;-)

Offline TFM

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Not really cheap, but affordable, just in case...


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Offline a7mag3ddon

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Nooooooooo. Cable arrived and text is sharp as hell but I have ghosting!! Any ideas why?