• Updated 2023-07-12: Hello, Guest! Welcome back, and be sure to check out this follow-up post about our outage a week or so ago.

Search results

  1. M

    SuperMac Spectrum 24/V Display Problems

    Good job!! You should probably just reflow all the RAM pins and maybe the SMT02 -- but carefully and only after thorough cleaning -- you could have microscopic debris shorts that have worked their way behind the pins. Blast it out with compressed air. Check all of the SMT02 pins for shorts --...
  2. M

    SuperMac Spectrum 24/V Display Problems

    If the traces are damaged, then they will be resistive and/or intermittent. The problem you are seeing with the broken column is 100% reproducible, so not intermittent. Try not to flex the board too much -- you could do more damage. Just carefully check resistance on the VRAM traces and look for...
  3. M

    SuperMac Spectrum/24 Series III Display Artifact Issue

    Good job. It could have been bad solder, debris or electrolytic corrosion. Unless you thoroughly clean the hole (and the pins -- to remove any oxidation/surface issues, there could be residual problems (and it might depend on the degree of via-trace dendrite invasion, etc.). If there is debris...
  4. M

    SuperMac Spectrum 24 Series I

    The interposer should be helpful. Anything directly connected to a NuBus line on the board could be ESD'd from handling (buffers, etc.), since people sometimes handle the NuBus connector from the bottom and touch (and maybe shock) the pins. It's an unknown. Also, if you have a PLCC puller, you...
  5. M

    SuperMac Spectrum 24 Series I

    Yes - there needs to be a crystal installed. There are no clock synthesizers on the early boards. Those came later. I think Spectrum/24 originally shipped with 64.00Mhz oscillator installed on the board and a 30.24Mhz in the box. If users wanted to use NTSC, they could call in for a 14.31818Mhz...
  6. M

    SuperMac Spectrum 24 Series I

    Cool - original Spectrum/24. Make sure the pin 1 orientation of the oscillator is correct when you are trying it and that you are using a standard monitor - like SuperMac 19" 60Hz or Apple 13" with a known good sync-on-green cable. The standard oscillators for that board (and also the...
  7. M

    SuperMac Spectrum 24/V Display Problems

    Seems like you're making progress. It's certainly possible that the BSR and DAC are OK. If you have identified a bad VRAM, you could just substitute or replace it. I think you have other boards that use the same parts. Or, you could use (or write) a board VRAM R/W tester. If any RAM is bad...
  8. M

    SuperMac Spectrum 24/V Display Problems

    Yes - CLUT/DAC - same. I shouldn't call it that - mostly just legacy metonymical slang. It's a DAC (that includes CLUT functionality). Within the DAC, drivers set up the CLUT values and/or luminance mapping for mono modes. The 473 is a triple-channel DAC, but I thought the board used it in...
  9. M

    SuperMac Spectrum 24/V Display Problems

    Looks like you've been busy! The reason you are seeing the common green channel is that I think it uses the green channel for up to 8-bit mode -- typical of SuperMac boards -- although I don't think the Bt473 cares which channel it uses (configurable) in lower modes. It only uses triple channel...
  10. M

    SuperMac PDQ, Spectrum 8, 24, Thunder ROMs

    @eharmon Yes - correct - more configs -- I was forgetting. Thanks. Eventually 1360x1024 and 1600x1200. The DSP board connections go all the way back to Thunder/24. The original Thunder/24 had a max of 1152x870. I don't know as much about later boards -- after '93/'94 -- but performance-wise...
  11. M

    SuperMac PDQ, Spectrum 8, 24, Thunder ROMs

    The V may have had more supported monitors or other hardware changes to consolidate manufacturing. And not sure if the DSP modules are the same or not. I know the Thunder/PDQ+ swap works, but I haven't tried the others. However, I think I have all of these boards.
  12. M

    SuperMac PDQ, Spectrum 8, 24, Thunder ROMs

    - There was only the original Spectrum/24, then Spec/24 III and beyond. - The Thunder/24, PDQ+, Spec/24 IV and Spec/24 V use all the same parts and the acceleration is SQD01-based. - I don't know if the Spec/24 V ROM is backwards compatible (haven't tried it), but Spec/24 IV should be (just a...
  13. M

    SuperMac Spectrum 24/V Display Problems

    You don't have to remove the port. Just make sure there are no solder voids and test from the connector with pin jumper wires.
  14. M

    SuperMac Spectrum 24/V Display Problems

    The RAM addressing is interleaved for speed (IIRC), which is why you see the successive banding. Also, I will just say that you are a wildman! ^_^ It's awesome!
  15. M

    SuperMac Spectrum 24/V Display Problems

    If you wiggled the card and the problem came back, then it could be a nubus data data line (which is card, not mac, since you tried multiple macs). Check the nubus lines and port carefully. It had an impact and could be damaged.
  16. M

    SuperMac Spectrum 24/V Display Problems

    I am traveling at the moment, so responding quickly -- a few more things... - The ROM stores 68K code that is loaded/executed by the Mac CPU in the slot address space. So, when there is a write to board memory - like drawing to the screen during Primary INIT, it is going over Nubus. It's just...
  17. M

    SuperMac Spectrum 24/V Display Problems

    Glad it's OK.
  18. M

    SuperMac Spectrum 24/V Display Problems

    Sorry - my post above should have said SMT02 (not SMT01). Anyway - it looks like there might be something happening in the lower right corner of the SMT02 in your picture -- is there a bent pin/short there? See the red dot. Maybe what I am seeing is just an optical illusion, but it looks like a...
  19. M

    SuperMac SuperView Review

    Be careful with any data you use in conjunction with the SuperView SCSI adapter (originally intended as a PowerBook big screen expansion) and make sure you have a backup. It may have a gremlin bug that could completely corrupt the mac hard drive (or maybe it is related to user error and SCSI ID...
  20. M

    SuperMac Spectrum 24/V Display Problems

    At primary INIT, the board you have is in 1-bit mode and the CLUT is being programmed for red (0) and gray (1) to display the SuperMac splash screen. Earlier SuperMac boards programmed the CLUT to black/white and used a half-tone gray screen and black banner (various Spectrum boards - Spectrum/8...
Top