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Using your Sega Dreamcast on a new TV

I had recently been playing my Dreamcast on my old TV, which had a VGA input. Using the DC VGA BOX, I had VGA and audio output from the Dreamcast and all worked perfectly.

In the last fortnight, I've picked up a brand new Sony KD49X8000D and it doesn't have VGA input! HDMI, Composite or Component... they're the options. It was time to browse eBay for options.

VGA to HDMI

Without doing any research, or reading the product description, I jumped straight in and purchased a cheap straight-through VGA to HDMI cable.

It was never going to work. It seems to only be for projectors where they transmit random signals via VGA plugs. Don't expect that an analogue VGA signal can just magically transform inside a cable to HDMI.

VGA to RGB

I then saw this cable at trash and treasure last weekend. It's got VGA at one end and RGB on the other. I thought that it might be component, so I paid the handsome sum of $2 to test it out.

I'd forgotten to test it, but just read online that it also wont work. The description of a similar cable here indicates that this is for specific projectors under specific circumstances.

MINI VGA2HDMI Adapter

I resorted back to eBay and looked for an 'active' adapter. I found this one, cheap, on eBay and thought I'd give it a go.

In the end, the cabling is a nightmare as there aren't nice small VGA cables available.

Super simple to connect. But it didn't work first off. Someone else has made this item work before, so I must have something wrong with my configuration. It could also be that my TV doesn't support the resolution over HDMI.

Uhmm... nope.... I then tried another HDMI cable and realised that this one seated in around 2mm further! And worked! Switching back to the other HDMI cable saw it working too: it just needed a bit more of a jab to make proper contact with the converter. Note! These converters are cheap and cheerful, so do be careful when hooking them up.

Check that out... you can see the TV LED at the bottom... that's the initial picture at 1:1 640x480. Very clear!

And then scaled... looking great. Sounding o..k.. a bit scratchy at times. Will check my headphone cable between the devices. Anyway. Success!

Final Note - Overheating...

This adapter is indeed cheap and cheerful! If yours stops working, then check my post here on how to apply a heatsink.

NEC PC-8201A Portable Computer – Black Screen

Here's a new acquisition. It's an all-in-one portable machine from the early 80s. It was sold cheaply as non-working and, indeed, it non-works.

I hadn't realised how big these things were!? I was expecting something around half the thickness and maybe 60% the width/height. It's actually a really nice machine and I do like the form-factor. This item came quite scuffed and 'used'. All to be expected and nothing to worry about. I purchased it since they seem to have a great array of I/O ports and programmability. They run Microsoft BASIC off-the-shelf and have 32kb of storage.

Initial Inspection

First signs of tear-it-down-before-turning-it-on showed up as soon as I checked out the battery pack. The batteries weren't in there, but there was a LOT of corrosion. The circuit board in the battery pack even seemed to have components missing? Did they corrode and disintegrate away?

After a good scrub, all was much cleaner... I had already decided to pull the main machine apart first though. Corrosion has a magical property of travelling inside metal (just like electricity) and conquering whatever it can get its green rusty mits on.

Of course, it had spread. The terminal and battery pack isolation switch were the main victims. Fortunately, it didn't seem that the tracks or other components were affected?

Both Isopropyl alcohol and cleaning wipes were used to clean up the board. Light scrubbing was also required in the hard to get areas.

Powering it up

After all the cleaning and soldering above, it was time to bite the bullet. I found 4 random AA batteries and slotted them into the pack. My multimeter showed 6 volts, so I slapped it in an gave it a go.

Flicking the power switch on the side gave no response. I had read online somewhere that the first thing to check is the "Back Up Power" switch. I initially thought this meant "use the internal battery", but it doesn't. It actually means "use the batteries you've just inserted". With this switched over, the power switch on the side saw the unit come to life... well... there were at least a few electrons flowing.

Black Screen Of Death

For now, we're going to disregard the damage to the LCD. you can see that something pointy has taken out a sizable area of the screen... but 95% of it will still be usable prior to needing to replace that.

After the power switch was flicked, the screen produced the result you see above. Trouble-shooting this is pretty straight forward. As per the instructions here, press Enter, then type BEEP and press Enter again. If you get a beep, then your mainboard is fine and your screen is crap. My mainboard was not fine!

The next bit of googlin' found this result on diagnosing and repairing a black screen. Turns out one of the 245 chips was only half-functioning. I love that the author also found errors in the service manual. Either way, the repair-man found a defective IC and replaced it... as that I had no way of determining what was defective, I started replacing everything.

Component Shopping List

From the service manual, I found the following replaceable chips at my local electronics store.

Original Chip	Jaycar's Version
40H139 : U1, U53,	74HC139 (ZC-4848)
40H386 : U51	74HC86 (ZC4835) IS NOT PIN COMPATIBLE! Jaycar therefore doesn't have a replacement.
40H245 : U13, U42	74HC245 (ZC4870)
40H373 : U15	74HC373 (ZC4874)
40H367 : U??, U??	74HC367 (ZC4872)
40H138 : U2, U3, U4, U5, U6	74HC138, but Jaycar doesn't stock it!
40H175 : U11, U12	74HC175, but Jaycar doesn't stock it!
603 Transistors	BC547?
115 Transistors	BC556/560?

Note: The above list is a work-in-progress. I'll update this as I continue identifying and replacing parts.

Find and Replace

Removing components from PCBs is always a challenge. Even with the best solder-sucker, you can still have a very hard time making sure every pin is free. In the end, as long as you don't need the existing IC, snipping legs and then removing those can be a much better option.

I've used sockets for each IC I'm putting in as well... I've no idea if this whole board is pointless, so I'd prefer to waste a socket more than an IC. I started with the 245 that was mentioned above and got nowhere... still the blank screen... I then replaced a 367 and had no luck either. This was really a crap-shoot and a very slow process. From here I thought there had to be a better option... so I consulted the service manual.

Troubleshooting via the Service Manual

I really should've started here when diagnosing the issues in this machine but, when I had first read it, I saw the word 'Oscilloscope' and got scared off. I don't have one of these, so I didn't think to pursue this area of investigation. I had since come back to it after realising that replacing each of the ICs was going to take a REALLY long time.

On page 54 you actually get to test each of the pins on the CPU itself. It indicates the pin and the expected voltage. Note that the CLK pin is meant to flip/flop and this can't be seen from a multimeter. All you can really look for is a 'half' voltage, as the flicking effectively provides 50% 0v and 50% 5v totalling 2.5v. All of the pins on my CPU came up OK as per the values stated!?

From page 85 of the manual, you get instructions on what voltages are meant to be seen from the power supply board when the computer is powered on. All but one of these turned out to be OK. Pin 10 was meant to be greater than 7.5v, but mine was only just over 7.0v. The manual then tells you that U2, Q16, C1, or D7 of power board are bad. Ok... this is good! Let's replace everything we can.

Something weird happened next. I didn't have the required components to repair the power supply, so I tidied up the desk for the evening. As I put the machine back together (aka. placed it into a pile of loose parts), I accidentally toggled the power switch.

Wait... what... we've got movement! The screen displayed a bunch of random rubbish. Sometimes a cursor, other times a heap of LOAD statements and at one point I could even type in a command... I didn't get a BEEP though.

The only thing I can attribute this to is that the power supply board received attention. I had shifted the caps around and also wiggled transistors. Maybe some of these had faulty solder joints? I should've measured pin 10 again here, to see if it all happened because of a 7.5v reading. Unfortunately, I couldn't get it back into such a state. I went ahead and purchased parts to fix the power supply. Unfortunately, I couldn't find the correct transistors at Jaycar to replace Q16 as per the instructions above.

I replaced all I could but still couldn't get the machine to do what I wanted. Actually, as I first started tinkering, the display of crappy text was satisfying. Towards the end, I hardly had a jumble of pixels. Toying with the ROM did seem to help... I wonder if the chip or socket area was damaged? Maybe static had fried it? Out of desperation, I attempted to swap some transistors around on the power board. Maybe that Q16 was the final issue. I did note that the 7.5v was still very intermittent. It didn't quite appear when the machine was half-working and only appeared at other random times... maybe the board was pulling too much current due to other issues and therefore was never actually going to let the power supply do it's thing?

Playing switch-a-roo with transistors revealed some information on the power supply. Swapping the 603s between Q2, Q16 and Q3 made either the speaker click, the relay click or nothing at all. To me this meant that one/some of the transistors were faulty. It didn't matter which as I didn't have a replacement. Trying to find actual 603s was impossible but, using the cross-reference tool here, I have just found out that BC556s are a valid substitute.

Or are they? Let's rewind a bit... I assumed that the transistor was a 2SA603... but it actually can't be. Using this complimentary transistor table, it seems that my transistors are 2SC2603 and 2SA1115. It would make sense that one was NPN and the other PNP. I therefore need BC547s (although they seem to be rated 100mA less and the pins are reversed!) for the '603' and BC560s for the '115'. Unfortunately, Jaycar doesn't have 560s, so I'll choose 556s instead, which are just have a higher voltage tolerance and a lower amperage. I might also order the correct components from eBay.

So, transistors... turns out that on page 108 of the service manual, the components are listed. I was totally correct on the transistor model... well, after I corrected myself. I therefore bought 20 of each from Jaycar.

Of course, I jumped the gun and didn't correctly review each component. The pins weren't backwards, they were actually out of order!

So, with the legs crossed, just enough, the order of the pins could be adjusted...

Whilst replacing the transistors, I also replaced the capacitors. Of course, one had to have exploded. Happened to be the 33uf that assists with the -5v output. I assume it's a cap that stabilises the voltage. I simply used solder to bridge the damage.

The results started off erratic... but then seemed closer to rendering a real screen?

And then it happened!

Keyboard didn't work.. screen was frozen... but shiiiiit... that's the actual main menu! I actually nearly have a real computer! I then replaced all the signal diodes on the power supply.

With the diodes replaced, the keyboard worked! Note that at this point in time, the board relay was not actuating on power on. It had previously, intermittently... but doesn't seem to be essential? Either way, as above, the menu worked and BASIC loaded. Unfortunately, once loaded, BASIC was useless with a screen full of junk. Any keypress resulted in Memory Full and a system beep.

I opened up TEX, typed in the obligatory sentence, pressed enter and the machine froze up... the work continues!

One step forward...

And then back to the beginning. I did something stupid over the weekend. On Saturday night I placed the ICs I had purchased over the top of the ICs they were to replace, so as to be able to see what ICs I still needed to replace/purchase. With these piggy-backed loosely, I closed the machine and put it aside.

Forgetting that I'd done this, I attempted to boot the machine the next morning... It presented the infamous black screen and not much else. As I shifted the machine to the center of the workbench, I heard parts move and instantly remembered what I'd done the night before. What a bloody waste of time I am; forgetting that I'd left the ICs in there and hence possibly doing all kinds of damage.

For the life of me, I could not get the machine back to where I was on Saturday afternoon. Such a let down! The only real goal was to hope that I'd only damaged mounted items and not the new items I'd purchased... then again, I could just re-purchase as I'll socket all the ICs.

IC Replacement

Solder suckers are fun, but Desoldering Braid is the best thing since sliced bread! Once you've removed the IC+legs from the mainboard, you'll find it quite difficult to remove the solder from the holes. Desoldering braid does this for you and does it quickly and cleanly. All you have to do is unreel enough to cover the hole and then press your soldering iron directly into the center of the area. The chemicals in the braid them somehow manage to attract the solder!

If it doesn't work the first time, then re-apply solder first. Only use the braid on holes that are full. If there's a gap, then the solder wont jump, it'll only flow! Also, the longer you hold the soldering iron there, the better. Watch as the solder flows into the braid and lift when it stops flowing up.

After removing the TC40H386P, and thinking that the 74HC86 was a replacement, I worked out that it wasn't. A hack was employed to get around this.

I lost a lot of faith with hacks like the above. Regardless, I ended up replacing half the chips on the mainboard and didn't get anywhere... it was time to wait for the oscilloscope to arrive.

IBM NetVista M/T 6825-M23

This poor machine was about to be sent to the recycle center... so I salvaged it and downgraded it. Getting Windows 98 to run was a challenge!

Windows 98 doesn't like more than 512mb RAM

Found this out the hard way... the installer would boot the CD, start installing and then fail randomly throughout the install. Once it actually made it to the first reboot and then failed to reboot. It threw an error on the dos prompt of which I failed to record. The machine had 512+512+128 in there (which was an odd combo anyway) and I reduced it to just one 512 stick. After this is worked fine.

Sound Drivers

I downloaded and installed around 20 different SoundMax drivers and had absolutely zero luck. 1 month later (when I finally had a use for the machine) I came back to get the audio going; I needed a full multimedia experience.

I checked out the motherboard and found that it had a AD1887 chipset... turns out that this was made well after the Windows 98 era and therefore finding drivers wasn't easy.

Fortunately, Totempole posted the same issue in the vogons forums! Unfortunately, his links are dead. A little googling found the correct file (although it stated it was for Windows 7 or higher?) which worked a charm! Here it is for safe-keeping: SoundMax AD1887 Driver for IBM NetVista Desktop Workstation (d63z32us.exe).

Note that if you want DOS Sound to work, then you need to specifically enable it.

And then you can play awesome games!

NVidia AGP Riva TNT2

This machine came with this card in the AGP slot. There's no on-board graphics in this machine.

It seems like 81.84 was the final NVidia driver to support Windows 98 but I somehow managed up with 71.84_win9x_english.exe installed. Display Properties shows that this card is an NVidia Vanta? Never heard of it. Running at 1920x1080 in Windows 98 SE is pretty random.. but great for the next trick.

Now to start producing Director 5 movies for this project and ... playing A-Train.

A-Train III – PC Engine

After finding A-Train for the MSX, the Famicom, the Amiga and the Megadrive, I googled a little more and found out that version 3 was released for the PC Engine. Of course, this is the actual version three, not I or II that were released on Japan earlier. It's on par with the first A-Train to be released to the west. I found a copy on eBay and couldn't resist!

PC.. Engine?

Yeah, this was a video game console released by Hudson Soft and NEC in Japan. It was later released in the west as the TurboGrafx-16. It was released at around the same time as the SNES and Sega Genesis.

This console made history as the first to have a CD-ROM expansion and then an inbuilt CD-ROM when the Duo was released. The console kept evolving and a second version of the PC Engine CD-ROM format was released. They named it Super CD-ROM². Older machines could be 'upgraded' via a System Card (HuCard) to be able to read the newer CD format.

Multiple variations of the PC Engine were built, check out the wikipedia link for more information.

A-Train III for the PC Engine

This version of A-Train has great sound effects and utilises the CD Audio for background music. It requires the Super CD-ROM² System Card to boot.

I don't actually have a PC Engine, so I did a little investigation on how to emulate it. Turns out that Magic Engine needs to be purchased and mednafen needs a serious amount of configuration work to boot off a real CD.

Running with Ootake

This couldn't be easier... download Ootake from here and install it. You'll find an icon on your desktop once installed; double-click this. Initially you're greeted with a disclaimer. Insert your Game CD and then choose CD-ROM. You'll need a system card image to boot into the machine as a Super CD-ROM², a little googling should get this for you without too much effort. Once you've selected the file, hit OK...

Now to work out how to play the game ... Ootake emulates the PC Engine Mouse and this game happily uses it, so it shouldn't be too different from the other versions!