🇬🇧 BBC Master Compact: Part 3 (Motherboard Fault) [ скачать в хорошем качестве

🇬🇧 BBC Master Compact: Part 3 (Motherboard Fault) [

Thanks to #PCBWAY for sponsoring this video! My BBC Master Compact has a weird fault where it won't work when in its case, even just resting without any screws. Remove it from the case and place the bare motherboard on my bench ... works perfectly! 00:00 ... Intro 01:09 ... Examining the board 02:20 ... Examining the bottom case 03:50 ... Faulty when in the case 06:45 ... Fine when out of the case 07:20 ... Expansion ports? 10:30 ... Removed dodgy composite video RCA jack ... weird video output 11:43 ... A few days later 13:05 ... Looks suspicious 15:50 ... Moment of truth ... 17:37 ... Channel outro & thanks Turns out that the right-hand stand-off in the bottom case had damaged two pins of IC22, the CF30050 I/O controller. When I re-flowed the solder on these and put it back into its case ... booted straight away! Finally. Next, I'm going to try loading some DFS software using my simple disk interface adaptor board. My Github page: https://github.com/BrettHallen/BBC_Mi... My Master Compact has these ROMs installed: MOS 5.10 UTILS 1.10 ADFS 2.10 The Master Compact is a cutdown version of the Master 128 that had the computer contained within the keyboard and a separate unit containing the 3½" drive and power supply. The keyboard was connected to the unit by a 5V power cable and a DB25 cable for the disk drive. Some further info here: https://chrisacorns.computinghistory.... You can run the machine with just a +5VDC power supply with 2.1mm plug (centre positive) - probably a modern USB charger is enough. The major chips on the board: 6522: Versatile Interface Adaptor (VIA) VC2069: Video ULA (or VIDPROC) HD6845: CRT controller (CRTC) SAA5050: Teletext character generator CF30048: CRTC Multiplexer CF30049: Peripheral Bus Controller CF30050: I/O Controller CF30058: Memory Controller (socketed) WD1772: Floppy Drive Controller (FDC) 65C12: CPU PCD8572: 1Kbit (128x8bit) EEPROM (socketed) There are some empty sockets for the RS232 serial support. ECONET support comes via a daughterboard that plugs into the motherboard. -------------------------------- Check out my Patreon for regular blog-type updates between videos - there is a free membership tier and two paid tiers (US$2 and US$5). There is also a one-week trial for the paid tiers so if you don't think it's worth it, then cancel ... no hard feelings ... I appreciate any support, even if it's just subscribing to my YouTube channel!   / thecluelessengineer   -------------------------------- Music by Karl Casey @ White Bat Audio https://karlcasey.bandcamp.com    / @whitebataudio