On 01/03/2010 20:47, Bill Sudbrink wrote: The 110V / 220V mod is all you need to take care of the power; the 50/60Hz mods are purely for the video. Actually I (and many others) found the modification for 50Hz wasn't bad on a Mk.II but rather less than perfect on a Mk.I, and there are some variations. The schematics in the Sorcerer 2 Technical Manual are: Master Timing for Exidy Standard Video Sorcerer Video Interface 30 lines 64 characters Sorcerer Central Processing Unit Sorcerer Dynamic RAM Section ROM Section I/O and UART Interfaces Cassette Interface Sorcerer II Power Schematic Expansion Chassis Motherboard The Master Timing is the one you'd want in order to understand the 50/60Hz change. Logically, the Power Schematic would be the one for 110V/220V, but it doesn't actually show the transformer primary. On a Mark II, the 50/60Hz is set by one section of a DIP switch at location 11A. Section 1 of that is on for 50HZ and off for 60Hz. When on, it grounds the /SEL inputs on a pair of LS157 muxes which are part of the feedback in a set of counters made from a couple of LS161s and an LS74. The other parts of that switch control whether you have 3 rows of DRAM (on) or 2 (off), 16Kx1 RAMs or 4Kx1, and 2 rows or 1 row. From the manual: "For 110V, the power supply transformer primary windings are connected in parallel; to convert to 220V, disconnect them and wire in series. Do this by cutting the black-yellow and black-red wires at the line filter, and soldering them together." On mine, they're neatly soldered together inside some sleeving. If you look carefully at the line filter mounted to the left of the transformer, you'll see that one terminal has a black-green wire going to the transformer, and that's the one that the black-red wire should connect to for 110V. The other terminal has a plain black wire, and that's where the black-yellow wire should connect for 110V. While you have the lid off, and are looking around thre anyway, check the big filter cap next to the transformer, and a somewhat smaller (usually blue) one on the PCB near the regulator heatsinks. These are two common points of failure on these machines. Another common problem is the 0.156" Molex connector on the main board, which can get very hot and start to go high resistance. If it looks brown, clean the contacts and perhaps replace the shell. Incidentally, there's a timing problem evident with some DRAMs, and there's a modification to fix it. The symptom is that a machine with 48K of DRAM only appears to have 32K, or at worst, doesn't boot with all 48K fitted. Another thing to be aware of is the serial port problem -- the original Sorcerers had a logic mis-design that meant that the RS232 line was held in the wrong state when idling. There's a software "fix" that doesn't work nearly as well as the authors claim, but a hardware fix is fairly easy. You /don't/ need any fix on a Mk.II and trying to make one will actually stop RS232 working. Have you got any software for yours? I've got a couple of things as MP3s, one or two old tapes that I'll investigate "one day", a few binary files saved to disk (I used to "save" down the RS232 line to a tape emulator on another machine, and load back the same way), and dumps of the WP PAC ROMs. I don't have the WP PAC manual; I do have the Dev PAC manual but haven't been able to find a dump of the ROMs for it (which is annoying, as I used to write Z80 code using the Dev PAC, decades ago). -- Pete Peter Turnbull Network Manager University of York

On 02/03/2010 01:15, Bill Sudbrink wrote: The things I described should match; they're from the Sorcerer 2 Technical Manual and a bit of my memory. The rest are the secondaries. I'm not sure about the solid yellow and solid black, but I'd guess they are taps for slightly different supply voltages (eg 110/120 or 220/240), and the rest is pretty much as the technical manualk describes: two primaries, to be wired in series for 220/240V and in parallel for 110/120V. I reckon you should split the black/white and white/black, and look carefully at the black/yellow and solid white connections on the filter. You might be able to see where the black/white and white/black once were, if it started life as a 110V machine. If not, you should find by doing a continuity test that the black/white is one end of the primary that has either the solid white or black/yellow at the other end, and therefore should go to the opposite side of the filter output. Similarly for the white/black wire. I'd replace those, in that case. All "on" should mean 50Hz (section 1 of the switch) and 3 rows of 18K DRAMs, so you have a 48K machine. Those certainly part of the video sync timing. Isn't there a 74LS157 at B19? The pads might be timing, but they might also be part of the ROM decoding, or used to allow signals and power to be re-routed according to the use of 3-rail EPROMs, single-rail EPROMs, or mask ROMs for the monitor. My Sorcerer 2 schematics only show the latter, and not at B19. Are your monitor and chargen ROMs mask ROMs or EPROMs? Unless anyone else with a Sorcer 2 can identify those, you might need to see what IC pins those connect to so we can work it out. Or just reverse the mods and see what happens. I'd sort out the 110V power first, though. Incidentally, the schematics for the original Sorcerer and the Sorcerer 2 are very similar, except for the IC positions. It's worth downloading the Tech Manual. At least you'll see how the PSU and transformer are arranged. -- Pete Peter Turnbull Network Manager University of York