Re: Yet another ROM adapter
Posted: Fri Dec 22, 2017 8:35 am
moordean, good advise about soldering SMD components. PersonallyI found that soldering any 1206, 805 or even 603 packages is not difficult with a tip 0.8mm dia. At first I clean the PCB with IPA, then apply a bit of good quality flux on the pads and finally solder with a small portion of solder on the tip. An ESD teasers are very helpful. When all SMD components are in their places I do final cleaning any residue of flux from the board.
I would not agree that the soldering the adapter to the ZX81 board directly is the solution. In my opinion any modification should reversible as far as practically possible. I don't like any mods that require traces cutting, drilling additional holes, and so on. I've repaired a few boards (mainly ZX Spectrums) where someone solder "add-on" directly to the board. In most of the cases there was a bad joint, broken traces or very badly overheated board with lifted/broken traces.
Coming back to your adapter, could you use all components in SMD packages including both capacitors in next revision of the board? MLCC 4.7uF/10V is available in 805 size. In KiCAD you can also find components' footprint for hand soldering. Pads are longer and they are really handy. Yes, they require more space on the PCB but it is not the case on your board.
I would not agree that the soldering the adapter to the ZX81 board directly is the solution. In my opinion any modification should reversible as far as practically possible. I don't like any mods that require traces cutting, drilling additional holes, and so on. I've repaired a few boards (mainly ZX Spectrums) where someone solder "add-on" directly to the board. In most of the cases there was a bad joint, broken traces or very badly overheated board with lifted/broken traces.
Coming back to your adapter, could you use all components in SMD packages including both capacitors in next revision of the board? MLCC 4.7uF/10V is available in 805 size. In KiCAD you can also find components' footprint for hand soldering. Pads are longer and they are really handy. Yes, they require more space on the PCB but it is not the case on your board.