I do love that @janbeta posts new videos for me to enjoy over dinner 🍕

#VintageComputing #VintageElectronics

I just uploaded the scanned and ocr'd (service) manuals in English and German for the 50+ years old Philips PM 2423 Digital Multimeter. They are very detailed and perfect for anyone who wants to repair and calibrate a unit:

https://archive.org/details/pm-2423-en
https://archive.org/details/pm-2423-de

#VintageElectronics #Philips #PM2423 #InternetArchive @internetarchive

Made progress on getting the broken Roland SoundCanvas SC-55mkII that I got for cheap on eBay to work! I was fairly sure a clock signal (or rather the absence of one) was the culprit, and after poking around the board tracing clock signals I found a spot where one abruptly stopped.

Turns out a 40MHz low-pass filter was missing entirely from the board! After bodging it with a wire (since it’s just a filter, so the worst that happens is noise causes occasional problems), the unit came up! 🎉 But the display has issues. Half of it is dead, and the first letter of the instrument name is garbled. This appears unrelated to the first problem, and suggests an issue with the display board itself; all lines going to the display look good.

Given that another filter on the board was already bodge-wired, and a 455MHz crystal (only needed for the remote) was cut out, *and* given this display problem, I think this may have been a parts unit for someone.

#electronics #roland #soundcanvas #vintageelectronics #synth

If you are getting started with servicing #VintageComputing gear or #VintageElectronics, you may be like me and scratching your head wondering about negative and positive sides/legs of capacitors.

I found the Identifying Capacitor Polarization page on DigiKey.com to be helpful.

https://www.digikey.com/en/blog/identifying-capacitor-polarization