Well the fuel gauge story is not quite over. My fuel line became disconnected after a couple of drives, spilling gas on the driveway when I went to take the car for a short errand today. I think I just didn’t get it completely seated before putting in the clips. Just in case, I’m buying new clips tomorrow. At least the fuel lines are easily accessible.
Archive for December, 2009
I needed to get an update #14 out there before something bad happens.
I’m declaring victory on the back and have rounded off corners on small traces. The effect is quite good. Here is a small image from the cad program and the same section from an original.
Stay tuned. I have just a few things to clean up on the front prior to declaring victory on that side.
Spent the afternoon replacing the fuel gauge sending unit on my ’04 Chevrolet Malibu. Had to drop the gas tank and two of the four bolts holding it in place were very hard to reach. What a pain – at least I didn’t have to deal with stuck or broken bolts. Last sending unit I replaced was in a ’91 Ford Escort and that car had an access panel under the back seat. So much easier to do that it is hard to imagine why having an access panel isn’t a standard design feature.
Had to buy an overpriced sending unit from Chevy, since aftermarket companies only sell the entire fuel pump assembly and that costs about $500. The wipers on the original unit were just plain worn out. I hope that this one lasts a bit longer than the original.
I’m still working on the design reviews – I hopefully will be done by Monday or so. Found an interesting less than obvious feature a couple of days ago. Take a close look at this image.
Do you see something unusual?
If you don’t see it, look again. Two of the traces are just slightly thicker than the others. At first when I was working on this project, I thought the variation was just some random variation. The reality is that those extra wide traces are carrying +12 volts and -!2 volts power around the board and are made intentionally wider than signal traces.
Still gathering parts – and emptying my bank account. Hopefully, by the end of next week I’ll have everything but a few commonly available parts in hand. I’ve also borrowed a cassette interface PCB, which I will need to build up in order to test the expansion port. I have a parts list for the cassette interface and will order those parts along with the last parts for the motherboard.
I keep finding little discrepancies between my PCB layout and the original. One recent example is on the silk screen under the power and video connectors. Based on the Apple II, I assumed that there was a silk screened box around the holes for those connectors. However I found an image of an original board that does not have those connectors installed. Sure enough, there is no silk screened box around those connectors. These sorts of changes are easy to make once the difference is discovered, but determining how the hidden portions of the original board looks, can be difficult, if not impossible. I’d part with a bit of money to get a hold of a good X-ray of an original Apple1.
I’ve added some good Apple 1 links, a complete Apple 1 bill of materials (BOM) and information about finding parts to build an Apple 1.
I’m running out of things to fix or improve on the PCB layout. I’m about to round off corners of small traces. I’m doing that last since once I do the rounding off, tweaking trace placement becomes a whole lot more difficult. Also in the plans is complete netlist check to make sure I haven’t botched some connection and run another pass of the CAD programs design checks.
Base motherboard kit price to go up to $400.00 from $350 on Feb 1, 2010.
Spam and the general unfriendlyness of phpBB has caused me to port my phpBB post over to this wordpress Blog – hopefully I’ll have better luck with this. I think blog software is better suited to what I am doing, anyway.
On a project of this type, sometimes you run across unusual features. Note the slightly different styles of R used. The R in the “IRQ” has a bent “tail”. The other “R”s on the board have a straight “tail”.