Sam's Modifications

ZX Spectrum +/48k - Composite Video Mod

2011-10-11T06:28:00.000-07:00

I wasn't happy with the picture quality of the RF output from the spectrum. So I decided to do the composite video mod. Rather than just disconnecting the +5v line and routing the video signal directly to the RF output. I decided to remove the modulator circuit entirely. I also found on this website, that it is possible get a cleaner video signal by adding a 10-16v 100uF capacitor in series with the video line. Here's the pictures I took when I modded my Spectrum 48k+ to do composite.

De-soldered the modulator from the spectrum board:

Removed the modulator circuit from the metal shielding/casing:

Added the 10v 100uF capacitor to the video output:

All soldered back on the the spectrum board:

Connected up ready for the initial test:

Works great and a much improved picture! I should of really took some before and after pictures:

The completed mod. Turbo loading from an mp3 player:

Heres's the orignial website for the composite mod:
http://womblesretrorepairshack.blogspot.com/2008/11/zx-spectrum-composite-video-mod.html

And again a usefull website with lots of modding information:
http://user.tninet.se/~vjz762w/rebuild.html

Getting into Sinclair ZX Spectrums

2011-07-15T03:32:00.000-07:00

Recently I’ve been getting back to playing around with some ZX Spectrum hardware. I originally picked up a ZX Spectrum +2 back in September of 2010. Played a few games on it then put in to storage so I could focus on other projects. Then a few weeks back I managed to get hold of two more spectrum systems. A ZX Spectrum + and a ZX Spectrum + 128k. They were both sold as faulty and untested, but I managed to get them both working.

I'm interested in these systems mainly for gaming, as there are loads of retro/unique titles for this platform. With a lot of them being freely available to download as TAP, SNA or Z80 “ROM” files.

But one thing that puts people off is that most of the games originally loaded from a cassette tape, that lead to slow loading times. To over come this issue there are a few programs available on the internet that allow loading of game much faster. This is known as “turbo loading”. More info here: http://code.google.com/p/otla/ I have successfully used this program to load games to my spectrums. I've also used an mp3 player to load games.

There is all so a piece of hardware realised for the ZX Spectrums know as the DIVIDE. That allows the user to connect standard IDE drives to the spectrum. So that programs and games can be loaded instantly from hard disks or compact flash cards. (I want one! I've yet to acquire one.) More info here: http://baze.au.com/divide/

One thing to put in consideration with all of the older spectrum models is that various keys on the keyboard will stop working over time. This is due to the keyboard membrane becoming worn out. So it is a good idea to get the membrane replaced. Various sellers on ebay and the web are offering newly manufactured membranes. Available for most of the older spectrum models. To get your spectrum’s keyboard properly working again. I replaced the membrane in my Spectrum + 128k as a whole row of keys did not work. Though be aware that it can be a bit of a faf to get the new membrane to work, because it has to be perfectly aligned for all the keys to work as they should.

Some useful ZX Specturm websites:

http://www.worldofspectrum.org/

http://www.1000bit.it/support/manuali/sinclair/zxspectrum/sm/service.html

http://www.dataserve-retro.co.uk/index.html

Acorn A7000+ Portable - The A7Kp

2011-06-08T06:25:00.000-07:00

Here's one of my latest completed projects:

The A7Kp

“A” for Acorn, “7K” for 7000 and “P” for portable.

A custom built (by me!) portable Acorn A7000+ RISC OS computer system.

The main features are:

Integrated 10.4 Colour TFT LCD using analogue RGB+HV video.
Uses an original Acorn A7000+ motherboard
Internal 9.6v 4600mAh NiMh Battery
Custom power/voltage regulator to supply the internally required voltages
12v 2A external power supply input
External mouse, keyboard, serial, printer and audio output ports
Internal 4Gb compact flash storage
Dimensions: 315mm x 205mm x 70mm
Weight: 2.5Kg

So back in 2008 I had an idea of making my own very portable or luggable style Acorn RISC OS computer. After reading about a few other people doing the same. For example the Lego A7000 laptop or the A9home DIY laptop. It wasn't until around October of 2010 that I actually started designing what would be the A7KP. The design I went with was a tablet style system utilizing an external keyboard and mouse, similar to the prototype newsPAD. I did want a built-in touch screen but I scraped that idea in the end. Because finding a mini touch screen that would work natively with RISC OS would probably be difficult and expensive. I started the main build, both electronics and the case around mid November 2010. I had the system finished by the end of may 2011. I worked on this project on and off over this period of time. Though if I worked on the project constantly I would probably had it finished in about a month and a half.

Some more pictures of the system:

How I did it and how it works

The Case

The case is built up from a number of MDF side panels with four wooden corner supports. The front panel contains the LCD screen. It is sandwiched between two 6mm and 10mm thick MDF panels, with a 2mm thick clear perspex screen cover. So that the bare LCD screen is not exposed. The LCD screen sits flush inside the 10mm panel. The four screws located at the front of the system allow the screen cover (10mm MDF and 2mm perspex) to be removed. The back and sides are all 6mm MDF. The back panel is removable and is held on with four screws, so that the internals can be accessed. All of the side panels are glued on to the corner supports with strong gel super glue. It is all painted black with four coats of mat black spray paint. The internal components are held in with various brass and plastic PCB mounts. Overall the case is quite strong and turned out pretty well.

The Electronics and Components

The system can be run from either 12v DC from an AC adaptor or 9.6v from its built-in batteries. As system uses an original Acorn A7000+ main board, all the required voltages to run board must be provided: +5v, +12v and -12v with the use of some voltage regulators. I used three switching regulators from Texas Instruments to provide power to the system board. A PTR08100WVD is used to provide the +5v. The A7000+ board draws 480mA on its +5v rail. +5v is also supplied to the compact flash card. A PTN78000A is used to supply -12v rail. And a PTN04050C is used for +12v. (9.6v is stepped up to 12v while running on battery). The total current draw of the main board and compact flash card powered by the three switching regulators without the screen is 550mA at 12v. The total current draw of the complete system is 1.2A at 12v.

The screen used in the system is little 10.4 inch TFT PC monitor for use with point of sale equipment. (I brought it off ebay for £24 on an liquidation auction) It runs from 8v to 12v and only draws 600mA at 12v that made it a good choice for this system. I removed the controller board and LCD module from its case. De-soldered its VGA and DC input ports so that I could wire it directly to the A7000+ main board.

I made a few modifications to the A7000+ main board for this project. I replaced and re-soldered four larger capacitors so that they would lay flat to the PCB. I removed some of the connectors from the PCB so I could wire directly to them, the monitor/VGA port and DC power connector for example. I also removed the original CMOS battery and soldered in an AAA 1.2v 250mAh NI-CD battery as the original battery sticks out from the motherboard and has a tendency to leak.

For the hard drive a laptop 2.5 HDD would work but would draw more power leading to shorter battery life. So I used a compact flash slot to IDE adaptor and 4GB compact flash card to save power. I can remove the card and connect it to my Risc Pc to access, add and remove files.

On a full charge the system can last just under 3 hours. I added a feature where by the user can put the system in to a primitive form of standby mode. There is a button on the left side of the case that can turn the screen on and off, but keep the A7000+ powered up. The internal battery is charged by hooking up an external charger to a connector on the right side of the case.

Here's the 12v DC input. Originally the input jack was fitted into a hole next to the main power switch. But when I installed the power regulator board, the back of the DC input jack was in the way. And the case would not shut properly. So I had to remove it and add a simple connector block on the outside of the case. I then filled in the hole with hot glue and a black sticker. Doesn't that good but does the job.

Here are the I/O ports of the system. An external PS/2 keyboard and mouse must be used.

Some internal pictures of the system showing all of the components.

Replaced CMOS 1.2v 250mAh NiCd Cell:

How the A7000+ mainboard is mounted:

Resoldered capacitors:

DC-DC convertor boards:

VGA port de-soldered and directly connected:

More pictures of the system:

Size comparison with the RISC OS 3 User Guide:

More pictures this project are on my photobucket:

http://s108.photobucket.com/albums/n19/Sam_thornley/Acorn%20AK7p/Building/

There we have it! My home made portable RISC OS computer system!

PSone Portable

2011-06-07T06:48:00.000-07:00

Here's one of my older projects but certainly not the first!

My home made Portable Playstation or PSone Portable.

The system specs are:

5" PSone Screen
Uses a PSone Console PCB/CD Drive
2x 3.6v 4600mAh NIMH Batteries (7.2V Total) (under 2 hours playtime)
Standard PlayStation non-analog controller. (When i first had a playstation back in the 90's this was the only controller i had and used.)
Tact switches for the d-pad and buttons, large red push buttons for L1, L2, R1 and R2. Rocker switches for main power, screen power (screen can be turned off to save battery).
Built-in memory card

I started building this system back in October 2009 and had it finished around February 2010. Like with most of my projects I worked on it on and off over this period of time. I ran into a few problems while building, I messed up the hole for the triangle button so it was slightly off. As my original plan was to have the playstation controller buttons incorporated in the case, but because I messed up it would not fit. So in the end I just left bare tact switches for the action buttons. Everything is perfectly playable and works fine.

Some more pictures of the system:

The full Build/work log is here over on the Benheck Forums:
http://forums.benheck.com/viewtopic.php?f=4&t=34220

Home Server UPS

2011-05-24T13:09:00.000-07:00

Recently I’ve been wanting to have some kind of power back system for my home server setup. Just a little project of mine. Though it would be cool to have in-case of an unexpected power failure while doing data critical stuff. Also I use the server to record CCTV images from a camera mounted at the back of the house, so having a power back-up system is a good idea. Rather than going the usual route of using a standard mains voltage UPS converting AC-DC-AC then back to DC from the server PSU. I thought I'd get and try out the picoUPS and a picoPSU from minibox.com. Since my server uses a low power Intel Atom mini ITX board i thought it would maybe save some power, because no power conversion would be needed.

Here's the picoUPS-100 from LinITX.com and a picoPSU-80-WI off ebay. From an Mini-Box authorized reseller! (I colour coded the spade connectors with red and black maker pens)

The picoUPS-100 is a miniature UPS with an on-board lead acid battery charger. And will automatically switch to battery when power from the input is lost. But in order to charge the battery properly the picoUPS needs 15-18v. So I used a 16V 4A laptop power brick from an old Sony viao laptop. While in normal operation the Pico UPS will output the same voltage as supplied, In my case 16V. Then when the power fails on the input the pico UPS switches to the battery dropping the voltage to 12V. Because of this a picoPSU with a wide input voltage must be used. As the standard picoPSU (80w and 120w) runs on 12v DC only so can not be used. So I used a picoPSU-80-WI that will run on anything from 12v to 32v. I also added some PCB feet to the UPS board so it can be mounted on something in future. For my backup battery I’m using a new Yuasa 12v 12Ah SLA off ebay.

Here's my mini itx home server setup:

(In case you're wondering its a Intel Atom D410PT, 512Mb RAM and 250GB HDD)

I removed the standard ATX PSU from the case. (It was located at the front of the case, I forgot to take pictures of it!.)

Then installed the PicoPSU-80-WI.

The cables that come with the picoUPS had to be modified to suit my needs. I added a 2.5mm DC power connector and swapped the spade connectors for some wider ones as the ones supplied would not fit the battery terminals.

Now here’s the complete setup running, with the picoUPS, battery, 16v 4A PSU and the home server. (Note all the old stickers on the shelf! It used to be part of a wardrobe, from when I was 10 years old. LOL)

I tested how long the battery would last during a loss of power. It kept the system up and running for nearly 4 hours! Quite amazing! I kept an eye on the battery voltage to make sure that it doesn't go below 12v. While running on battery the voltage drops slowly from around 12.60v to 11.80v. Over the 4 hours that I tested, my battery voltage got to 12.32v before I restored power to the system. So it has the potential to run for longer. The picoPSU does not have under voltage shut down so the lowest voltage i would let it run to would be 11.90v. In a real power cut, I should be able to shut down the server before the battery voltage gets too low. So there you have it my UPS project.

More information about the picoUPS:

http://linitx.com/product/12438

http://www.mini-box.com/picoUPS-100-12V-DC-micro-UPS-system-battery-backup-system

Other poeple using the picoUPS:

http://e.molioner.dk/projects/ups/

http://www.greenillusion.com/?paged=2

Mega-Boy a Sega Megadrive Portable

2011-03-15T08:25:00.000-07:00

Here's one of my recently completed portable system projects, the Mega-Boy. A home made portable Sega Megadrive console mod.

Its a fairly standard portable with a simple design layout with a standard A,B, C and start buttons. The main specifications are:

Custom 6mm MDF case with wooden corner supports
5" PSone Screen (unmodded CCFL) with screen cover
Uses a Sega Genesis 3 PCB, region modded for 50Hz PAL
Cart Slot at rear of unit (carts stick out but i don't care :P )
Powered by 6x 1.2v 2600mAh NiMh Cells (7.2v total) Just over 2 hours play time
Player 2 port
DC 7.5v input and Battery charger input
RGB video with mono sound
165mmx195mmx43mm
Dimensions: 165mmx195mmx43mm

Pictures of the completed system:

The System

Back of the system

D-Pad and buttons

Front of the system

7.5v DC-IN and Charger IN

Player 2 Port

Cart Slot on the back

Playing Sonic 2

Playing Rocket Knight Adventures

Playing The Revenge of Shinobi

Playing Earth Worm Jim

Inside view of the system

In worked on this portable from about June 2010 to December 2010. I worked on it slowly on and off over this period of time. (there was no rush!)

The moddedbybacteria forum WIP/Build log with internal pictures can be found here:
http://moddedbybacteria.freeforums.org/sam-s-megadrive-portable-the-mega-boy-t455.html

The moddedbybacteria forum completed project post:
http://moddedbybacteria.freeforums.org/sam-s-sega-megadrive-portable-the-mega-boy-t983.html

A quick YouTube video:
http://www.youtube.com/watch?v=APjmn_Pv-dE

Hello!! I'm new here!

2011-02-22T13:20:00.000-08:00

Hey people, Sam here. Thought i would create this blog to show other computer/console modders out there (or anyone who likes this kinda stuff) what i get up to in my spare time. On here you will find information about my current projects, past projects, hacking information and anything else that i think is relevant!

Cheers!
-Sam