Friday, September 19, 2008

Rebuilding a Laptop Li-ion battery II

This one is for a  HP laptop that is about 2 years old.  I suspected the cells would be the same 18650 cells used in the Fujitsu rebuild.  Apparently HP did a better job of sealing up the battery and I kinda wrecked it trying to get the insides out.  Hopefully I could glue this back together later on.  Off to the same dealextreme site to order the batteries and another week of waiting...

Well, cells came back, and after weeks of putting it off, I finally put it back together.  A little bit of super glue put the thing back together... Mostly.

Monday, August 4, 2008

Connecting a Dreamcast to the Internet

All Dreamcasts came with a dialup modem.  There was an ethernet adaptor for it but only a few were sold before Sega pulled the plug on the Dreamcast.  So, what I wanted to do was get it connected to the internet without pulling up a giant phone bill (and possibly internet fees).  You could get one of those prepaid dialup cards you can get from your local convenience store, but most people (me included) already have a broadband connection at home.

My plan was to connect it to another dialup modem with nothing more than a phone cable between the 2.  This did not work at all.  The modems are expecting some kind of phone line with some current flowing through it.  What I did would be similar to connecting 2 handsets together with some phone wire.  You can talk as loud as you want, but nothing is going to come out of the other phone's speaker.

What I need is some kind of line simulator that will fool the modem(s) into thinking that it's actually connected to a phone line.  I found this after some searching  After obtaining the parts and assembling it together:

It did not quite work out.  Same as before, nothing. NO CARRIER.  Turns out I needed to do a bit of tweaking with the resistor.  The value stated in the article may have worked for some modems, but for my specific one, I had to wire 2 of the 390 ohm resistors in parallel just to get a 8mA current... the articles I read say that the phone company provides 30mA ... and 25mA would have been enough.  but after that, it worked.  I will do a little more adjusting of the resistor if needed later on.

I used a digital multimeter to check the current flowing through the circiuit so you see the leads I used still in the picture.
I had to run minicom (a comm program) to type "ATA" to tell the modem to answer.  After that I quickly exit without hanging up and at the command line type:

pppd /dev/ttyS0 115200 crtscts proxyarp passive

After that.. a peek at /var/log/messages reveals connection successful.  And I can ping the dreamcast's IP.  Another machine on the lan can ping it as well (that's what proxyarp means).  I will be automating this later on... but for now I'll leave it a manual process just to get it running.


Saturday, August 2, 2008

Apple IIGS RGB video to Component converter

There is a fair amount of retro devices that output RGB.  But these were RGB in TV frequencies.  If you try to hook it up to most VGA monitors, they will not sync properly and you would probably get a picture with lots of lines (if you get a picture at all).  The monitors designed for these devices were readily available a few years back, but they are recently becoming more scarce.  Another way of using these signals is using a standard television with a SCART input and a RGB to SCART connector.  Most PAL TV's have SCART inputs (or so I heard).  Having gone through a local TV store recently,  I checked the TV's, both LCD's and CRT's ... somehow they stopped putting SCART connectors on the newer sets and it's been slowly replaced by component input (Y Pb Pr).  Also most NTSC TV's never had the SCART connector.

Well, that aside, another way to view the output of these devices would be to use the standard composite video out to your TV.  So I take my Apple IIGS, hook up the composite out directly to the TV's video in and ...

As you can see, the stuff that are supposed to be in black and white are tinted with color fringes.  This would be somewhat acceptable for games and applications with mostly graphics.  If you are using it with 80 column text, or graphical text, you will soon get a headache from trying to read it.  The Apple IIGS composite video circuits automatically disable the colour burst signal so you get something in black and white.  This improves the readability somewhat but on screens with combined graphics + text you get the same problem.  That is the main reason why the came out with RGB monitors.

Well, my TV has the standard Y Pb Pc component input.  If you connect something meant for RGB to it, it works, everything is as clear as RGB, but with the wrong colours.  That's a good enough start for me.  After searching around for a DIY RGB to component converter, I found one in my local electronics store already packaged as a kit.  It was published as a Silicon Chip article.  I proceeded and assembled the kit.  After that,  I think the TV expects the SYNC signal with the luminance (Y) signal, or it just displays the "no signal" blue background.  

A quick question to Tony Diaz (thanks Tony) gets me what I needed.  It is safe to just tie the composite SYNC signal with the Green output to have "Sync on green".  After wiring a makeshift  D15  IIGS RGB with wires leading directly to the RGB to component converter I finally have the results I was hoping for.  Here's are comparisons of using the composite "video in" image and the "RGB converted" image.  

Last 2 are output of the converter.
The image above is the same TV using the composite "video in".
This one is the same as above, but using the converter.  

Close up of the converted image.  Note the clear black and white text.

Last 3 various images of composite out.
Image of the same screen on converted output

Last 2 are pictures of the Tour of the Apple IIGS.  They are "graphical text".  You should be able to tell which is which ;)

That's the box itself.  Excuse the mess in the background.

Another 2 images for comparison... again you should be able to tell which is which.

More examples

Entire screens.

Tuesday, July 1, 2008

Installing a PC motherboard into a quicksilver G4 case

I have had an Apple G4 quicksilver case in storage for some time now (Thanks to Wade for hand carrying it all the way from Brisbane).  My original reason for getting it, was to house my Imac G5 logic board.  Well... after measuring the inside dimensions of the case,  I found out that there is no way I'm going to make this fit, unless i do a lot of sawing and hacking, which would leave very little of the case intact and part of the logic board would probably be sticking out... this somehow defeat my purpose of retaining the external (and if possible internal) appearance.  

This Imac G5 logic board is now running attached to my desk and is what I use to update this blog, I will leave this topic for another day.

Anyway.  I looked around for a good place to buy some cheap parts.  I am putting this together as a MythTV box so I brought that into consideration when choosing the parts.  After searching around, I found  this low price computer store  

After looking through their price list, I ended up with the following:


I was choosing between a Gigabyte 945GCM-S2L and an Asus P5GC-MX/1333.  They are mostly identical (layout, chipset, etc.)   Well, the Asus costs $2 more, but the Gigabyte has 10/100/1000 onboard ethernet, whereas the Asus only had a 10/100.  So I ended up with the Gigabyte.  $59.


At that time the quad core processors still costs a fair bit (plus MythTV isn't going to need that much CPU power.) Based on the MythTV forums, even the lowest end E2140 is more than enough for what I want to do.  Balancing the costs (and the thought that I might use this as a desktop computer later on)  I ended up with a E2200.  $107


1G DDR2 Kingston. $32

Hard Disk:

Seeing that the main reason I want to upgrade my old MythTV box, is so that I can record/watch High Definition (HD) content.  The old box can actually do that, but the onboard SIS video chipset only displays a weird green screen whenever I try to display HD content.... plus it didn't have an AGP slot.. only 2 PCI slots which was already taken up by the 2 tuners I have.  So I thought a really big drive would be helpful... I could record months of shows before I need to erase some.  So after considering everything,  I chose a 750 Gigabyte seagate hard drive.  $247.00

That's all the parts that (I thought) I needed.  Next was to test fit the motherboard:

Looks like a good fit.  Once I could modify the back panel the PCI slots should line up properly with the apple back panel covers just right.

Next problem is the G4's power supply is not standard ATX.  To make matters worse, it looks like it's broken.  At that time I couldn't be bothered to attempt to repair it (I may someday) so I just decided to put the innards of an ATX power supply in the G4's power supply case.  This preserves the look at the back and the power cord still goes into the same place.

Shown here on the left is the original Apple power supply,  on the right is the cheapo ATX power supply.  Size is almost the same.  No modification was needed to transfer the ATX innards except drilling a few screw holes. 
Here is the ATX parts screwed on the Apple power supply case.  You can see some of the screw holes have to be enlarged, and one (upper left) has to be drilled.
Here it is all screwed up and working. 

I then somehow managed to modify the case so that the motherboard fit.  I had to cut a hole in the back panel because the G4 wasn't ATX standard.  I had to remove some of the original screw standoffs because they dont match the motherboard's and they would short something out if I leave them in place.  I then replaced them with metal PCB standoffs.  I remember after having done all that the case refused to close and I had to desolder some of the capacitors and mount them lying down to keep them from hitting some part of the case.  In the excitement I also somehow forgot to take any pictures of this and all I have is the finished product:

I will someday have to take this all apart for cleaning, and I will take some pictures and update this entry.

Tuesday, June 24, 2008

Modify PAL Atari 2600 for S-Video output.

I got an Atari 2600 from ebay some time last year 2006. It's one of those "vader" editions. Unlike the one I had growing up (which was a NTSC model from the US), this one is a PAL model. After hooking up the antenna to the TV, I was ready to play some retro games... or so I thought.

The PAL unit came with an IEC 169-2 connector (no it wasn't RCA). I did recall that the NTSC unit came with a TV/GAME switch box so that you can choose between antenna to watch TV or your game but the PAL unit didn't come with one. The back of the TV also had the same anttena connector so I just plugged it in.

Then I spent hours trying to tune the TV to get the picture to come out clear... I tried all the different PAL systems and B/G came out the best (others had bad/no audio, no colour, etc). The best picture I got was washed out, and had some snow in the background.

Now, I was thinking that somewhere inside the unit the console probably works with some kind of composite signal, and it might just have a bad RF modulator. Or maybe the coax cable was shot? At any rate I looked around the internet for a possible "video out" solution. I found something better. S-Video. From this site:, a circuit was published. This isn't exactly the simplest of circuits, there's 2 other solutions I found, one involves just a bunch of resistors, and the other was the same mod without the IC. But where's the fun in that? Besides this circuit also isolates the video circuit from the 2600's circuits, so if I were to do something stupid, like feed the s-video port some voltage, or hook it up to an ADB (apple desktop bus) port, it will only affect the video circuits I added. Plus, it doesn't put any load on the circuits like the other mods.
Since the article already explains what you need to do in detail, I'm not going to repeat all of that here. After obtaining the required materials this is how it ended up looking. This was the original RF cabling, internally it was RCA:

This was the main board with the shielding in place:

You have to untwist 5 of these to remove the shielding:

I used wire wrap wire to connect the circuit to the connection points. I did not make any changes to the existing circuit so i can revert it back to the original condition if I ever decide:

I made the output cable long, like the original RF cable so you can pull the console far from the TV, since the controller cables are so short.

It's time to hook it up to the TV

Now the moment of truth:

That was definitely a lot better than the RF cable. Well I have to assemble the unit back together and try out some other games: