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ymk

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Everything posted by ymk

  1. The current through the LED and resistor is the same and the sum of the voltage across each add up to 5V. Typical forward voltage through red and green LEDs is 2.1V. This leaves 2.9V across the resistor. 2.9 / 180 = 0.0161 A. Voltage across the LED will increase slightly with current, but this is negligible. For blue/white LEDs with a forward voltage around 3.6V, the same resistor would pass less current.
  2. Any LED that can tolerate 16mA will work fine there. If you want to reduce brightness, you can replace R111 with a higher value.
  3. I'd look at the brightness pots, both the external and the trim.
  4. I am biased since I sell it, but I recommend the MacSD, which can handle hard drive and CD images, and recently, floppy/partition images as well. You can mount multiple floppies at once and work with them at SCSI speed. No reconfiguration via USB is required. Also, changing cards on a Classic can be very easy with some modifications.
  5. Firmware v0.10.0 is now available and adds a new "composite" device type. This allows the use of multiple partition images (floppy, MiniVMac, etc) under a single SCSI ID. ProDOS and FAT disks work with the appropriate extensions. Once a directory is bound to a SCSI ID in the config file, images added to that directory are included automatically. Up to 60 images total may be mounted. This update also fixes issues noted by @cheesestraws: Partition type 0x0B is accepted in addition to 0x0C (except for firmware updates). Filenames in the config file are now case insen
  6. There's no active audio circuitry on the analog board. The speaker runs straight to the logic board connector.
  7. I'm thinking this as well. Looks like only half of the VRAM is available to the main bus, but all of it is being displayed. A stuck VADR line into the muxes can result in portions of the display repeating, but that's not what you have here. I'd look closely at the lower A lines. Are you checking these with a scope or DMM? A continuity test won't tell you about a short to GND, etc.
  8. Very cool. Though my PSU is working fine, this could allow a quieter cooling solution. A charge pump might be another way to get the -5V rail if current requirements are low.
  9. I have been running a fanless, clear case SE with a MacSD 24/7 without problems. The PSU PCB is not enclosed for visual and cooling reasons. It pulls 28 Watts from the wall and the hottest point I can measure with IR is 51C around the flyback transformer. However, I'm not sure if the @maceffects case passes IR. My Classic, which also has no hard drive pulls 30W, but has a slow 80mm fan to keep it cool.
  10. If you send me one, I could print you a set made of TPU at a reasonable cost. PM me if interested.
  11. Probably. I don't know of any replacements offhand, but Mouser is a good place to start.
  12. Measure the resistance. It's not worth risking the audio circuit over a questionable speaker.
  13. It's not exactly a fair comparison. Macs couldn't paint the entire screen with 320x200 like PCs could. Slow Macs had to either play in a tiny 320x240 window or use pixel doubling, which still had a cost. Unlike pixel doubling, the every-other-row rendering in Duke Nukem 3D actually reduced video bandwidth, speeding up the game significantly. On the other hand, 640x480 meant when Macs got Command & Conquer, four times the battlefield area was visible, making it a far better experience.
  14. Why not run native 68K Doom?
  15. I posted an album of a MacSD installation in a Classic. Like Byte Knight's setup, it uses an SD card extender and RGB LED.
  16. ymk

    Classic + MacSD build

    Restoring a Classic with retrobrite, logic and analog board recap, custom air intake and discreet MacSD upgrade. The face and cover of the Classic were brightened with 40V peroxide solution and sunlight. A custom, 3D-printed air box mounts a larger Noctua Redux 80mm fan. Fan RPM is reduced by a string of four 1N4007 diodes. For easy SD card access without removing the Mac's cover, a slot extender is mounted to the analog board, near the picture controls. The first step is cutting an H pattern in the sheet metal with a rotary tool. I bent the ta
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