I was lucky enough to pick up edition 15 during a Dragon show in 1988. It's a really good magazine with interesting electronics and OS9 articles among other things and I would love to read some more.
Many thanks to Franz for taking the time to scan them in
Great to hear you got it working and you certainly have my sympathy regarding eyesight. Mine has deteriorated to the point that I can no longer do fine work without a big illuminated magnifier.
The MKII trace looks like what I would expect. The ISS2 trace looks like something weird is going on like the scope connections are reversed, or is not connected to the LS86 output. Ignoring the inversion and distortion the two waveforms are the same.
Can't recommend a good wall wart I'm afraid Just a random thought: I've not measured so can't say for sure, but a laptop PSU must be built to a far higher standard than a typical wall wart. At least I've never felt like I'm being electrocuted when using a laptop. If you can find an old 12V laptop s...
The culprit is probably common mode noise which can be surprisingly hard to get rid of. This will be bouncing relative to the mains (and therefore ground) at the PSU end and turned into a signal at the monitor end. Ideally you would attempt to block with a decent common mode choke close to the PSU a...
Hi, Unfortunately this is a normal 'feature' of a Dragon. It's just dot crawl resulting from a lack of fixed relationship between the pixel and chroma clocks. Later versions have a 2-22pF trimmer cap in the position of C7. This can be adjusted for best appearance but it will drift due to temperature...
Hard to make out the details on my copy of the ISS2 schematic but it looks like that pin is the 'padded for PAL' /hsync, in which case the MKII equivalent is IC14 pin 6.