Putting the Hummer DTV board inside a Jiffy Box

This will be the second generation of my DTV conversion. I used an identical jiffy box on my original NTSC DTV (click here to see that one) I am making this one a little better using some of the things I learned on the first one. Some new features of this one is an internal RF shield and two different audio-outputs. One is a regular RCA output and the other one is a 1/8" phone jack so that if I wanted to connect a pair of computer speakers to it, I could. The DB-9 connector on the side is not a joystick port. It is, in fact, a user-port. The hummer-DTV doesn't appear to have joystick ports readily available. I may eventually be able to use a joystick in that port as I'm planning to reprogram some old games to use the memory address of the user-port instead of the joy ports. I also didn't use the plastic PC-Power Supply connector on this one. I thought I would like that on my first one, but it was to difficult to insert and remove. So on this new one, I used a regular barrel DC power jack.

First I measured and drilled all the holes for the different ports. I used a pocket knife to slowly scratch away the plastic until I got the right shape and size. I put mounting screws in the bottom for the board to screw down to. I took aluminum tape and coated the inside with it as an RF shield. I soldered a wire to all the ground points on the various ports. At this point the new box is ready for the board to be mounted.

I also put aluminum tape on the inside of the lid.

This is a rear-view showing the various ports on the back.

This is the cable I use for power. It has the convenience of the standard PC power supply plug that I like to use around the house on my 5V and 12V projects, but is much easier to attach and detatch from the DTV box.

This is the inside when it was mostly finished. Had not yet connected the user-port. See annotations of where I used the original daughter board via motherboard stand-offs. I also kept the origina ferrite bead.

Here is the completed front of the unit. Here you have the power switch, LED, and reset hole (use a paperclip) and the PS/2 keyboard port.

Here is the finished setup. You can see my 1581 disk drive just over to the left, almost out of sight. I'm still using a 5" home-made sony Playstation monitor for the time being.

After flashing the kernal to rid the need of the resistors on the user-port, I finished wiring up the user-port to the 9-pin DSUB on the side.

Mistakes and Brainfarts - Yes, I realized a few mistakes at the last minute. The worst mistake was removing the wires for the keyboard and IEC that I had originally inserted through the tiny holes and soldered. I wanted to use new wires but I discovered that once removed, it was darned near impossible to ever push another wire through those holes. I tried desoldering wick but it would never remove the solder deep in the holes. The holes were so tiny it was extreemly frustrating. It took an hour to get 3 wires back down in those holes and the other 2 I just eventually gave up and soldered them to the top of the board so they are a weak connection but now it shouldn't matter. My advice to you is if you ever solder wires in those holes, don't remove them.

Another thing I didn't realize. I had conveniently soldered the ground on all the ports together (video, audio, IEC, keyboard, user-port, main power, etc) but I later discovered that the ground for the audio/video is actually not directly linked to the rest of the grounds. So I had to re-wire that. I also had to cut a small slice in the aluminum tape I had used for RF shielding to keep the two grounds seperate.

Final words - First I will say that the shielding I put around the box made a big difference. I had been fighting a mild, wavy interference pattern on the screen the entire time. I wasn't sure the shielding would help, but it did. The picture is now crisp and clear as can be! It looks as good as a real C64 in composite mode. Even better than my V1 DTV that I did last year.And of course the Luma-fix made a big difference too. I never did the chroma fix, as the colors look fine the way they are and I knew that would be a big job moving those extra resistors. I did have that extra luma-correcting resistor connected (680 ohm that goes to ground) but removed it. It was causing too much noise on the audio line and the improvement was only about 10% better. So I took the clear audio over the better luma seperation.

So far I have only connected user port pins 0-2. Those are the only ones I've used so far in my experiments. I'm exhausted from this project so I wanted to get it finished. If I need the other user-port lines later, I'll go add them. Maybe by that time I can patch the kernel not to look at those lines.

I also really like the speaker jack I made. I took the opportunity to hook up the speaker system for my Pentium-4 desktop computer, which includes a subwoofer, to the DTV and play some SID music. I still say the original C64 sounds better, but it still sounded pretty good.


Back to main DTV Hacking Page