_________________
http://WilsonMinesCo.com/ lots of 6502 resources
The "second front page" is http://wilsonminesco.com/links.html .
What's an additional VIA among friends, anyhow?

Sorry; I didn't realise that the board was 4 layer; I must say, for PTH chips (And those in PTH sockets) it does seem a little overkill though

(As a final note, there is one other reason to ground pour your board: Thermal conductivity! The one I currently have out to manufacture will be stuck to a heat sink, with the ground pour effectively acting like a heat spreader for the chip)

yeah - it's an interesting discussion, and these are crucial issues for the consulting engineer, but I wouldn't want to discourage any beginners: up to a few MHz, with 5v supplies, for hobby-grade reliability, anything goes. If you want to sell something, or if you've gained a bit of experience, there's always more knowledge you could apply.

Imagine if you never dared to hook up an LED flasher on a breadboard because you had more to learn about ground planes.

Overkill? The inner layers made it so much easier to route the board, since I didn't have to concern myself with ground and power trace placement. It matters not that most of the parts are PTH. The benefits of the 4-layer design are still valid.


There's nothing on this board that runs remotely hot enough to be a concern. The disadvantages of filled planes substantially exceed the essentially non-existent benefits.

_________________
x86?  We ain't got no x86.  We don't NEED no stinking x86!

In a marathon slobbering session last night, I assembled my POC 1.0 computer. Amazingly enough, I was able to slobber the SOJ32 SRAM package on the first try and not get any faults, bridges, etc. The trick, as described in a U-Toobe video I watched to see how it's done, is lots of flux (I used a flux pen, which works very well), a very small and clean soldering iron tip, and a modicum of patience. Once the SRAM was done the rest was easy, being all through-hole. I made one assembly error in reverse-installing an electrolytic but fixed that. I will post pictures of the completed assembly as soon as I have them.

All the critical circuits have been metered out and it appears there are no faults. It should be possible to put the juice to this thing and not fill up the shop with acrid smoke or crowbar the power supply. I won't have time today to power it and see what happens—perhaps on the day after Christmas. I'm afraid my wife may try to stick the soldering iron into where the sun don't shine if I work on this thing on Christmas Day.

Speaking of working with small SMD packages, has anyone here devised an alternative to hand soldering to mount those things? Anyone figure out how to make a reasonably good equivalent to a reflow oven?

_________________
x86?  We ain't got no x86.  We don't NEED no stinking x86!

I understand a lot of people use a relatively inexpensive toaster oven for this work, but it obviously limits the size of the printed circuit board you can use.

Skillets are also reputedly popular

Hot air paintstripper? Or hot air attachment to a butane soldering iron?

_________________
http://WilsonMinesCo.com/ lots of 6502 resources
The "second front page" is http://wilsonminesco.com/links.html .
What's an additional VIA among friends, anyhow?

How did they determine the correct temperature to use and the amount of time to "toast" the PCB? It sounds kind of dicey to me.

BTW, contrary to my earlier post, I decided to put power to the POC today and at least determine that the reset circuit was working. It was, so I figured as long as I had the thing attached to the power supply, I might as well put the Ø2 oscillator in the board and see if there was any sign of life. My ancient Beckman 'scope (mid-1970s vintage) displayed a lovely square wave on the Ø2 circuit, so that's out of the way.

I should have stopped there, but since I had a clean Ø2 (as clean as the old 'scope can display it), I decided to insert the MAX238 transceiver and verify that the required EIA-232 logic voltages were present. They were.

Next step, which won't happen today (my wife told me to quit fiddling with my toys and get ready for our company that's coming here for Christmas Eve), is to plug in the MPU, EPROM and Dallas timekeeper and see if she goes or blows.

Ain't electronics fun?

_________________
x86?  We ain't got no x86.  We don't NEED no stinking x86!

_________________
http://WilsonMinesCo.com/ lots of 6502 resources
The "second front page" is http://wilsonminesco.com/links.html .
What's an additional VIA among friends, anyhow?

Obviously, the temp would have to be sufficient to melt the reflow on the PCB, with a little extra to spare. The metal parts would heat much faster than anything else, so the oven could be very hot to get the process over with as quickly as possible and reduce heat soak into the parts themselves. I'd be reluctant to try this without more info.

_________________
x86?  We ain't got no x86.  We don't NEED no stinking x86!

_________________
http://WilsonMinesCo.com/ lots of 6502 resources
The "second front page" is http://wilsonminesco.com/links.html .
What's an additional VIA among friends, anyhow?

Here's some info about using a toaster oven as a reflow oven. It would seem the process shouldn't be too tough with 50 mil pitch components. The author gives some info on temperatures and timing but is careful to mention that it's "art." Just don't crank up the temperature too high or your new creation becomes "black art." As I have three unpopulated boards left, as well as some extra SRAMs, I may give it a try. The worst that could happen is my board and SRAM (literally) become toast.

_________________
x86?  We ain't got no x86.  We don't NEED no stinking x86!

Used to use a hot air gun to remove SMT parts at a previous job. Was able to salvage and reuse chips nicely. The trick was to keep the heat over a large area so it all heated up evenly, or you would warp the board.

Soldering was by hand, though...

_________________
"My biggest dream in life? Building black plywood Habitrails"