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  1. Y

    Nearly torn cap on Mac SE/30, need advice

    It means heat it with your iron as you push it down. If you try to flatten it cold, it will probably break.
  2. Y

    Nearly torn cap on Mac SE/30, need advice

    You could flow the pad and push it back down with tweezers. Install the cap and use a bit of extra solder to anchor it to the via.
  3. Y

    Analog board RIFA Replacement Not Working

    Did you forget the deflection coil connector?
  4. Y

    Cloning the Farallon MacRecorder

    I'm glad you got it working. A circuit like this would provide that protection. It's a more stable, filtered power supply that also allows the Mac to send (on MCU_RXD). The diodes should be Schottky types:
  5. Y

    Cloning the Farallon MacRecorder

    It has a positive and negative supply (V1 and V2). V3 is a clock signal. If your rails come from the TX lines, multiply the two resistors by 5-10x to reduce current.
  6. Y

    Cloning the Farallon MacRecorder

    Does your design have a -5V rail?
  7. Y

    Cloning the Farallon MacRecorder

    Here's a simple inverting circuit:
  8. Y

    Cloning the Farallon MacRecorder

    Inverting or non-inverting?
  9. Y

    New LC owner questions: display, PSU

    I think breaks in CLUT data lines can cause this.
  10. Y

    Transformers for homemade LocalTalk/PhoneNet dongles

    The math works the same as parallel resistance. If you measure the impedance of a single transformer at 230.4 and 460.8 KHz, you can divide those figures by the number of adapters connected. I don't get how feeding TXD- and TXD+ directly into a transformer is safe. Is there never DC across them?
  11. Y

    Transformers for homemade LocalTalk/PhoneNet dongles

    Would a transformerless design be possible using capacitive coupling?
  12. Y

    LCIII Recap - Apple design fault -47uF reversed!

    The mistake is easy to confirm with a DMM, in seconds.
  13. Y

    Quantum Prodrive possible repair

    I make those and they do work. You can check the item feedback. It prevents contact with the sticky rubber and won't interfere with the parking mechanism. You don't need to expose the drive internals more than this:
  14. Y

    Transformers for homemade LocalTalk/PhoneNet dongles

    This could be worth a try: https://www.mouser.com/ProductDetail/Mini-Circuits/ADT1-1%2b?qs=xZ%2FP%252Ba9zWqZtqep%2Fn39ANA%3D%3D
  15. Y

    Word access odd Address Exceptions on 68K software - were they ever used?

    Which exception? 020+ doesn't require word alignment as far as I know.
  16. Y

    SE/30: Invert screen pixels?

    It should. An XOR IC would give you a normal/invert switch input.
  17. Y

    Feature comparison of the various SCSI to SD options?

    It is not. BIN is a 2352 byte per sector rip of an entire disc. The track layout is described in a separate CUE/TOC file. ISO is a 2048 byte per sector rip of just a single data track. The extra 304 bytes of error correction, sync, and other data are discarded in this format. The IMG and...
  18. Y

    Anyone have an SE speaker?

    My best guess based on its size, 250mW. No, the peak to peak was only 6.8V. I set the volume to 7 and played all kinds of sounds. 6.8V was the max Vpp the scope recorded. I used a 100Hz sine, but it doesn't make a difference. I simulated the speaker as a resistive load, which is worst...
  19. Y

    Macintosh SE/30 Schematics (modernization effort)

    Found an error on UA9. The labels for the inverting and non-inverting inputs are reversed:
  20. Y

    Anyone have an SE speaker?

    I ran some simulations with 63Ω, 8Ω and a dead short. The highest peak to peak voltage I recorded from an unloaded SE/30 speaker header was 6.8V, so I simulated with a sine wave with the same peaks. 63Ω speaker: 21.8mW R10: 9.4mW Q1/Q2: 54.1mW 8Ω speaker: 17.7mW R10: 59.8mW Q1/Q2: 170.0mW...
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