Colour A500+ composite output?

mjnurney

mjnurney

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Is it possible to do this?

The A500 is bw but the 600/1200 & 1000 are colour.


Cheers
 
Does it ? I don't know with out digging an a520 out of storage.

Is the colour compisite signal missing on the 500?
 
The A520 does indeed have Colour Composite & RF. Naff picture though :(

No idea on what trickery is missing on the A500's built in composite port though. They even mention it being B&W in the manual, stupid idea.
 
Cheers guys. I don't mind a slightly hazy pic in games :)
 
It's not hazy, it's actually really clear, just pixely if that makes sense. You'll see when ya try it :)
 
Im no expert (by a long shot!) but would it be possible to just cut the mono line and take it from the RGB port and solder a wire from that to the old mono out line?
 
Tajmaster said:
Im no expert (by a long shot!) but would it be possible to just cut the mono line and take it from the RGB port and solder a wire from that to the old mono out line?
Click to expand...

Unfortunately not - there's no composite video available at the RGB port, and the A520 contains an RGB-to-colour-composite converter (which I presume is the first stage of generating an RF-modulated signal.)

As an aside, the A520's composite out is significantly better than that of my A1200, which is somewhat over-bright. The A520's output is much better, though maybe not quite as sharp.
 
Isn't the Amiga 500+ just an Amiga 500 with minor updates? If so the answer is no. ;)

It would need a whole new reworked mobo to do that.
 
@Mike

my friend, the composite port on the A500/A500+ is only monocrome as it doens't have an colour encoded into the comp signal, - the comp signal is derived from the video hybrid -

the Video Hybrid takes the 12 digital inputs of 4x RED, 4x Green and 4x Blue, and derives colour intensities of these which it then outputs to the Video port - along with Sync's voltages and grounds - unfortuantely there is no colour encoding of the RGB only Luma (Y) is provided with the Sync Signal I beleive.

The Hybrid outputs R,G and B, also SYNC - with a CXA1145 (sony Composite / SVideo [Y/C]) encoder and the right clock frequency (for PAL) you could convert the output to either Colour Composite or even SVideo (Y/C)

or buy / build one that connects to the video socket - or just get an RGB SCART cable.
 
For those of us not 100% anointed with the High Priesthood of Digital Electronics (like our pal Zetr0 here :bowdown:) I was wondering if it would be possible to disconnect the mono composit plug, hack the case off of an A520 and rewire it between the RGB PINS and the mono plug and build the whole thing inside the case (I have no idea if there is space for it.. Quick and dirty solution but with the case on you wouldnt notice, and voila you have color composite built in! :roll:
 
@ Zetr0

Does the A500 have the CXA1145, or did it use the earlier MC 1377? I thought the A500s had the Motorola chip.

*ponders*

Edit: They had the Motorola MC 1377 in the A520 - see here:-

http://www.amiga-stuff.com/hardware/mc1377.html

It may be easier to wire that chip in on a small breadboard, then disconnect the connection from middle pin of the Composite video RCA jack to the main board, and wire in pin 9 of the MC 1377 to the RCA jack middle pin.

All the signals required are on the 23-pin video port, so it's just a case of taking wires to the appropriate inputs of the M1377 chip and tapping off a composite out. Leave pin 20 disconnected for PAL video, ground it for NTSC.

You could take the MC 1377 chip out of an A520, but I would prefer it if you bought the chip and spared the A520.
 
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This sounds very interesting :)
I had considered doing the same with an old modulator.
But got a new scart cable in the end.
 
Yep, just checked.

RGB, Sync and and 12v are are available at the 23-pin connector. This could be worth a punt with a MC 1377 chip.
 
im confuzed i think my a500+ is colour using the RGB scart connection at the back isnt the 500 the same?
Wouldnt it be easier just to use the rgb output.
 
Johnim is right; what we are pondering is converting the monochrome composite output of the A500's RCA jack socket to colour. If this can be done, you don't necessarily need the A520.
 
Merlin said:
@ Zetr0

Does the A500 have the CXA1145, or did it use the earlier MC 1377? I thought the A500s had the Motorola chip.
Click to expand...

Pretty damn close, just different bit of kit, the A520 modulator at the heart uses the MC1377 colour encoder, infact with a little hackery you can get SVideo out of an A520 modulator box.


Merlin said:
*ponders*

Edit: They had the Motorola MC 1377 in the A520 - see here:-

http://www.amiga-stuff.com/hardware/mc1377.html

It may be easier to wire that chip in on a small breadboard, then disconnect the connection from middle pin of the Composite video RCA jack to the main board, and wire in pin 9 of the MC 1377 to the RCA jack middle pin.

All the signals required are on the 23-pin video port, so it's just a case of taking wires to the appropriate inputs of the M1377 chip and tapping off a composite out. Leave pin 20 disconnected for PAL video, ground it for NTSC.

You could take the MC 1377 chip out of an A520, but I would prefer it if you bought the chip and spared the A520.
Click to expand...

yes, I see where you are going with this, but the MC1377 is really a bad choice given virtually anything else!, the MC1377 produces way to much noise and as such I would recommend near enough anything else as replacement (including two paper cups and a bit of string!)

But in all seriousness - given the option - for the simplest integration, I would use a CXA1145M or P varien, these are infact used in the A600 and A1200, interestingly they are used in a variety of consoles including the Sega MegaDrive.

Now rather than rummage around ripping Megadrives apart, there is a very cheap Fujitsu CXA1145 compatible (about $2.50 from farnell) - I will dig up my notes and post'em when I get a moment, and also put together a small PCB for the community.

With this all you need to do is tie down the VREF's the R,G and B, provide an XClock / CCK (colour clock - 4.43361875 MHz PAL / 3.58 Mhz NTSC) and a sync(s)

I would add a small 10 - 15pf ceramic cap between the clock and chip just to reduce noise from the +5v / pcb rf pickup.

A small board could be made and the comp track of the composite out from the hybrid could be cut and redirected to this board providing Composite out - alternatively, one could even add a small amplification to the Y/C output of the CXA1145 (or compatible) and provide SVideo output as well - there is plenty of backplane space to mount it.
 
Thanks Keith,

I knew we were thinking along similar lines, with different hardware. ;)

I think a little circuit board with a CXA 1145 compatible chip to convert the monochrome composite to colour would be a really good and cheap hack, and would allow RCA to Scart cables to be used on the A500 with no A520 hanging out of the back (I always thought that the A520 was an ass-nasty way of doing things from a hardware point of view).

It's not that bad from a wiring in point of view either. R,G,B, Clk and Sync, Vcc, Gnd and Comp Out. Very do-able. (y)

The Composite Out would probably need to be a screened cable, but that would be a benefit in reducing noise interferance.

Add a sticky pad to mount it inside the A500's case and I think we have a winner.

This enables the A500 to catch up with the A600 & A1200 with full colour composite out. It could probably be hacked into other retro hardware too - bonus! :)

Put me down for a couple right now.

What to call it? How about the Colour Wizard..??
 
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