Thanks, got those ordered.

Also finally got the parts and time to make up a power lead. It's.. crude. Amstrad 15 pin DIN to ATX socket for plugging into a standard ATX PSU. I've a nice light Compaq PSU with a -5v volt line I'm going to use.

I just tested it and the power light comes on the machine so seems to be good! I quadruple checked all my connections with the multimeter before I powered it on - even testing the molex connector and the ISA slots to make sure the voltage was going where I'd expect it.

Hi there,

After finding a dumped Amstrad 1512 (with keyboard), I currently find myself where you were... a standalone unit but no CGA monitor, cables or power.

I understand from reading online that the PSU was integrated to the Monitor and that it was rated at 57 Watts. I am hoping to buy a cheap plastic case and fab my own PSU for this unit, if I can find a cheap donor online. Having found the pin out for the 14 pin DIN, I will look to solder together a male connector for the 1512. The next phase would be to create a 9 pin DIN to CGA to VGA (if possible!) which should be interesting.

Could I ask how everything turned out here in the end... did the power cable you made work ok etc? What was the power rating of the PSU that you used?

If you could re-post the picture, or any other pictures you have, that would be appreciated.

Thanks in advance.

386_junkie wrote on 2018-01-14, 12:18:

Could I ask how everything turned out here in the end... did the power cable you made work ok etc? What was the power rating of the PSU that you used?

If you're still looking for a solution, I just made it work for myself last night:

PSU is done by a cheap 12V 300W mini ATX converter board from China (smaller ones might do also, depending on how many devices it needs to power inside). Since -5V and -12V are only routing to ISA, I am ok with the missing -5V rail (which isn't used by more than a very few cards and could probably be easily converted from -12V).
The connector can be found on Ebay also, it's the same as the Atari Floppy.

My graphics adapter uses a regular round 8 Pin DIN and goes to a 9 pin DSub. Looking at the schematics for the monitor I found 75 Ohm pull-downs (1/2W) and 100 Ohm resistors on the signal path. So, adding those, I got usable signals.
The composite sync is then routed through an LM1881, now handing out the vsync. Both vsync and csync go into Luis' MCE2VGA, where I slightly modified the schematic to invert everything back to regular CGA (Trying to do this outside the FPGA degraded the quality in my test setup too much).

In the end, I only needed to move the c_left_border by about 40 pixels to get the image centered.

This way, the Amstrad PC1512 returns from being a brick without its monitor to a perfectly usable system - right now, it just needs a dedicated MCE2VGA. Maybe there is a way to detect these inverted signals and automatically switch to this special mode - but this was my first dabbling with an FPGA and someone else's code, so I am unable to tell right now if it's really possible 😀

MJay99 wrote on 2020-03-10, 17:52:

Maybe there is a way to detect these inverted signals and automatically switch to this special mode - but this was my first dabbling
with an FPGA and someone else's code, so I am unable to tell right now if it's really possible 😀

Hello, good evening! 😀
If inverting is all it needs, an 4000 (4009 ?) or 74 series chip (74ls04 ?) could help, provided it is fast enough and level compatible.
A few months ago, I used one of such chips to invert the state of a serial port pin..
(More precisely, a DM7402N 2-Input NOR Gate. The trick was to combine two inputs to make it an inverter)
More information -> https://www.youtube.com/watch?v=ioEHqJ-unI4

https://en.wikipedia.org/wiki/List_of_4000-se … grated_circuits
https://en.wikipedia.org/wiki/List_of_7400-se … grated_circuits

Good luck! 😀

As mentioned before, there's a litte more needed than just adding an inverter (but it is one of the things to do). A little more important, though, is the splitting of the CSYNC and adding pull-down resistors to the signal lines (as can be seen in the Amstrad's service manual).

Since I always wanted to try Kicad, I've modified Luis Antoniosi's MCE2VGA a little to incorporate the LM1881 with the accompanying resistors and capacitors and also the pull-downs. I've also added the resistors to the signal path (as per service manual of the monitor).

Attached pictures show the result - first the part of the PCB sporting the 1881:

Then the PCB, thanks to a fast, one week delivery from China:

First power-up with the original Firmware of the MCE2VGA (moved to the left via the monitor):

Then with a dumbed down version and changed PLL (plus doing the inverting of signals inside the FPGA):

There is one thing I wasn't fully ok with: The 75 Ohm SMD pull-downs, even as 1/2W (as listed in the manual) do get rather hot - things were working and they did hold up, but changing them for higher values (>150 Ohm) seemed like a better choice in the end.

Good evening
I've found a 1512 but no monitor and no keyboard, as i can see a vga adapter can be made but what about the keyboard? Maybe we should start a converter project

stargazer wrote on 2021-09-06, 21:36:

Good evening
I've found a 1512 but no monitor and no keyboard, as i can see a vga adapter can be made but what about the keyboard? Maybe we should start a converter project

I'm actually restoring a 1512 myself at the moment. I will post some pictures soon, but in a new thread. A few things helped me planning this, regarding the psu and VGA the methods described in this thread combined with some blog posts. My keyboard works but perhaps with the information from http://www.seasip.info/AmstradXT/pc1512kbd.html it would be possible to develop a converter?!

So it it actually possible to run one of these machines without the monitor? Everywhere I look online it says nope, you need the original monitor. I recently bought a PPC512 and i'm developing a love for the Amstrad asthetic 🤣

Hiddenevil wrote on 2021-11-12, 14:30:

So it it actually possible to run one of these machines without the monitor? Everywhere I look online it says nope, you need the original monitor. I recently bought a PPC512 and i'm developing a love for the Amstrad asthetic 🤣

yes, the 1512 works without monitor if you use a psu with adapter, but the cga-ish output needs some conversion too. That's what this thread is about, specifically the video conversion.

MJay99 wrote on 2020-04-28, 21:10:

There is one thing I wasn't fully ok with: The 75 Ohm SMD pull-downs, even as 1/2W (as listed in the manual) do get rather hot - things were working and they did hold up, but changing them for higher values (>150 Ohm) seemed like a better choice in the end.

Unfortunately, I already ordered the resistors, perhaps I will do a v2 of my build in the future. Just nicely asking: Would you mind to share the Files for the PCB?

PdXY wrote on 2021-11-12, 14:55:

Hiddenevil wrote on 2021-11-12, 14:30:

So it it actually possible to run one of these machines without the monitor? Everywhere I look online it says nope, you need the original monitor. I recently bought a PPC512 and i'm developing a love for the Amstrad asthetic 🤣

yes, the 1512 works without monitor if you use a psu with adapter, but the cga-ish output needs some conversion too. That's what this thread is about, specifically the video conversion.

Thats pretty cool, i only really took a glance at this thread because I'm curious how I hook my PPC512 up to a TV/monitor..From what I can tell, the portables are very similair to the desktop units. This is pretty much my first experience with CGA and CGA monitors.

PdXY wrote on 2021-11-12, 14:58:

Unfortunately, I already ordered the resistors, perhaps I will do a v2 of my build in the future. Just nicely asking: Would you mind to share the Files for the PCB?

Since I'm no legal expert and it's based on someone else's work (albeit on a MIT license) I'd rather not post them here (since I only seem to be able to use a Creative Commons License and not a similar MIT one). But, I certainly don't mind sending you the gerbers directly - I just need to dig them out again. If you're in Europe, I could maybe even send you one of the surplus PCBs I still have laying around.

You just need to know that you also need a slightly modified code for the (~25€) Altera FPGA board - and both the SRAM, LM1881 and resistors on this daughterboard are SMD devices.

MJay99 wrote on 2021-11-12, 16:04:

PdXY wrote on 2021-11-12, 14:58:

Unfortunately, I already ordered the resistors, perhaps I will do a v2 of my build in the future. Just nicely asking: Would you mind to share the Files for the PCB?

Since I'm no legal expert and it's based on someone else's work (albeit on a MIT license) I'd rather not post them here (since I only seem to be able to use a Creative Commons License and not a similar MIT one). But, I certainly don't mind sending you the gerbers directly - I just need to dig them out again. If you're in Europe, I could maybe even send you one of the surplus PCBs I still have laying around.

You just need to know that you also need a slightly modified code for the (~25€) Altera FPGA board - and both the SRAM, LM1881 and resistors on this daughterboard are SMD devices.

That would be a very nice birthday present for me - I cannot send PM yet, but I will contact you as soon as I can 😀

MJay99 wrote on 2021-11-12, 16:04:

Since I'm no legal expert and it's based on someone else's work (albeit on a MIT license) I'd rather not post them here (since I only seem to be able to use a Creative Commons License and not a similar MIT one). But, I certainly don't mind sending you the gerbers directly - I just need to dig them out again. If you're in Europe, I could maybe even send you one of the surplus PCBs I still have laying around.

I thought that's what the fair use option was for, for things that might be covered under other copyright conditions. My own pics/content I post under PD or CC, but anything from elsewhere I mark fair use just in case.