Hacking a DVI cable to build an ADC to DVI converter

In the last post, I mentioned that my powermac G5 came with a video card that had 1 ADC and 1 DVI out. I wanted to hook up 2 screens to it and do not have an ADC monitor. (besides, the 25v line intended to power the ADC monitor is under-spec in my homemade power supply.)

Well, I took out a standard DVI cable and carefully opened up one end:

The pins on this single link DVI-D cable are not complete, and Apple used some of the non-existent pins on the ADC side of things. I had to move 3 pins (1, 9 and 17) to the area in the middle (4, 12 and 20). I drilled holes using a PCB drill and pulled out the pins with long nosed pliers. I then placed them (pins and all) on the ADC port of the video card and applied some epoxy to the area around the hole (the holes were too big).

This is after only one pin is moved:

This is after all 3 pins were moved.

I then carefully used a good combination of shrink tube on the wires so that nothing will short.

After testing this to verify that it works, I epoxied the black part back on to the shell. Now I have 2 screens hooked up to the Powermac G5.

Rebuilding a Powermac G5 power supply using ATX partsI

I have recently acquired a dead Powermac G5. The previous owner said that he brought it to the service center and its going to cost ~$600 to get it a new power supply, and that was all that it needed to be able to run again.

Well after getting the unit home. The first thing to do is test it without doing anything. Who knows, it might actually NOT be broken. In goes the plug... Pressing the power button results in... nothing.

So next step would be disassemble the unit. This is the intake fan:

This is the side of the unit with the cover off:

These are the covers for the heatsink

Because I did not have the correct service manual for this unit, I took the logic board out before taking out the power supply. I realized later that I only needed to take out the lower CPU to accomplish this (and yes I did take it out again ... but more on this later). I also read somewhere that there is supposed to be a cover on top of this power supply that is now missing, the service center must have forgotten to put it back. Some of the cables were also disconnected, again, my guess is that the service center did not bother to plug it back in as it is broken anyway.

This is the power supply. It is the biggest computer power supply I have ever seen. The middle connector is as big as a standard 24 pin ATX connector.

This is what's "under the hood" of the power supply.

This is the label stating how much Amps is needed by each line. A standard 600W ATX supply should satisfy these values. The only thing missing is the 25Vsb line. From what I have gathered, only the ADC out (for special apple displays) would use this. At this point I was not too concerned about the 25Vsb line.

This is the whole power supply's internals:

After the past experience with blown capacitors, I was hoping this is another case... No such luck. Poking around with my voltmeter revealed that the fuse was blown. I have a spare 250V 10A fuse that i quickly put in. Who knows, it may just be the fuse. I replace the fuse and then plug it in... poof: smoke comes out and the fuse is blown again.

A Careful inspection of the power supply board reveals that there are switching transistors whose legs are melted, there is also a crack on the board, and that there are more surface mount IC's at the bottom side of the board:

Some of the IC's are burnt too much to be able to read the writing on them. Ok... I was going to try to "component-level" repair this one, but at this point, it looks like it would be more feasible for me to substitute an ATX power supply.

After getting a 550W power supply from a nearby computer store and testing this with a spare PC motherboard and verified everything working, I cut all the wires coming from it, and desoldered the cables from the original G5 power supply board. I connected everything to the corresponding voltage but left out the 25Vsb.

This is how it looked after the operation:

I used shrink tube to insulate the individual wires to keep it clean (electrical tape would leave a sticky residue). After double and triple checking my connections with the voltmeter, I am ready to plug it in. Before I put all the screws back I should test it and see if it actually would work:

So, it's the moment of truth. Plug it in and press power button... Power supply fan runs... red LED lights up on motherboard... but no startup chime. Repeat... same...

Of course (duh). There is no RAM. (double duh). After installing a pair of 1Gb sticks of PC3200 DDR memory (from my iMac G5):

Pressing the power button now gives the easily recognizable apple startup chime, or as a good friend calls it, the "jeng" sound. That's all I needed to hear, out comes all the cables, out comes the 2nd CPU... put the power supply and everything else back on...

And it all works. Both CPU's detected, About this mac says it's a "Dual 2 GHz PowerPC G5". I did notice it was a bit noisy. My wife described it to a coworker as "it's as if there is an airplane about to take off". After doing some more reading, I think I may have put the processors back the wrong way (swapped the 2). The logic board seems to "remember" the CPU ID of what was there before, and keeps a thermal profile stored in non volatile memory. This thermal profile would be specific to that particular CPU. If you were to replace any of the CPU's (or like what I did, swapped the 2) the logic board was programmed to "play it safe" and spin the fans (all of them) at full speed. I have 2 options, take the CPUs off and swap them back (no way). Or run what is known as "thermal calibration". Running thermal calibration took about 30 mins (about 15 mins for each processor), after which the fans are running at their normal speed now.

After all that I used the computer for a few days, and noticed that the power LED was not lighting up. It wasn't lighting up either during sleep (it's supposed to look like it's "breathing"). After taking out the front panel connectors and power switch, testing the LED reveals that there is nothing wrong with it, nor with the cables connecting it to the logic board. The only thing that could be wrong would be, apple must have used the 25Vsb line for the LED. I found a 24V switchmode power supply at a local electronics store, and after taking out the power supply again, I was able to put it inside (there was lots of room left). This power supply came with a voltage adjustment knob which I changed to 25V with no problem. This unit is only rated for 25W so as long as I dont go about plugging in an ADC monitor, I should be fine. After plugging it in, The LED now works.

I used the DVI connector to connect it to my monitor. I wanted to hook up 2 monitors, but the other connector was ADC. Well... as this is a different topic, I will write about it another time.

Blown capacitors

Recently I have come across several items that wouldn't power up.  They either blink continously after being plugged into the wall, or just blink once after hitting the power button.  

Upon opening up one of the units (a LCD monitor), several of the capacitors look fatter than they were supposed to be.  The tops are conical instead of flat.  I opted to just replace all of the capacitors, making sure I got one with the same (or higher) voltage and temperature rating.  As soon as it was replaced,  it turned on easily.

Another unit came from a former co-worker.  It's a Thecus N5200 NAS box.  This unit, like one of the LCD screens, keeps blinking when you plug it in.  The owner was told that it must be the motherboard and that he should ship it back for replacement.  He was also assured that his data could be retrieved if he hooks up his drives to another unit.  Because I have the exact same box, we were supposed to hook up his drives to my NAS and recover his data, as he does not know how long it will take a replacement to be sent.

Before doing anything, though, I wanted to see for myself what the symptoms looked like.  So I hooked it up to a powerboard and plugged it in.  Like the LCD screen it was blinking on and off.  I said, this is more likely a power supply problem rather than motherboard.  I pulled out my power supply and swapped it in, and the unit came back to life.  We left it plugged in and started copying data off the drive.

While it was doing that, I asked to have a go at the power supply.  I would have to break some seals and since warranty is long expired, there is no harm in trying.  Off came the screws.  This was a very compact power supply and very different from standard ATX (Although it did have a standard ATX connector).  I had to unscrew 2 huge heatsinks and revealed the capacitors.  Sure enough 2 of them were "bloated".  I took some capacitors from my spares bag.  One was an exact replacement, the other was not (electronics store already closed).  After taking a long time to put the heatsinks back, I plugged it in.  No clicking sound.  That was a good sign.  we plugged it into my unit and it came to life, booted up.  We then decided not to continue copying and just put the whole thing back together.  It's been over a week and I haven't heard anything about it so I'm assuming it is still working.

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.

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 http://www.jagshouse.com/modem.html.  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 10.0.1.201:10.0.1.225 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.

Success:

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.

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 http://msy.com.au.  

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

Motherboard:

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.

Processor:

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

RAM:

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.