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  1. J

    Quantum Prodrive possible repair

    The freezer trick can affect all sorts of things. I've encountered IC's and transistors that became temperature sensitive and could be coaxed to behave sometimes by heating or cooling them. I suspect the rubber bumper is the cause of the Quantum drives sticking. I worked on two Minolta color...
  2. J

    External SCSI CD drive on Macintosh Plus

    That's exactly what he said
  3. J

    Macintosh Plus problems

    Discharging the CRT is really nothing to be scared of. I use a clip lead with one end clipped to the metal part of a small screwdriver and the other end clipped to the metal chassis around the tube. Poke the screwdriver under the suction cup looking thing and you may get a small static pop as it...
  4. J

    Summer Project Ideas - Thoughts?

    IMO a more interesting approach would be a modern accelerator card that plugs into the pds slot, although that's another several steps up in difficulty. Doesn't make much sense to me to go through all the trouble of stuffing the guts of a laptop into a larger clunker box, that's really no...
  5. J

    Ehman external and a Seagate ST-157N

    It looks like only some of the wires are used, so you could change the connector to a more common 6 pin, or make an adapter. Those 0.1 pitch IDC connectors are pretty standard. This place has a ST-157N listed for $44, still a bit high IMO but a LOT more reasonable than greed-bay...
  6. J

    Macintosh Plus problems

    Loss of focus at high brightness is a common symptom of a worn out tube, although if it's that rapid of a change I would look elsewhere first. Your HV may be low, or you may have a problem with the focus divider.
  7. J

    Are brightness fluctuations always a capacitor problem?

    This doesn't sound like a capacitor issue unless there are SMT electrolytics that have leaked out on the board. Does the Color Classic use the RPM control pin on the SWIM to control the monitor brightness like the Classic does? If so a good start would be monitoring brightness control line to...
  8. J

    Seeking advice with my Macintosh Plus

    The flyback/LOPT transformer is known for failing on these and can result in a dark screen. I had to replace the one in my own Plus around 15 years ago. You could also check to make sure the filament in the neck of the tube is glowing, it's not very bright but should be clearly visible in a...
  9. J

    An Idea, header + epoxy = easily replaceable cap

    That's certainly a potential issue, although even collectors who use their vintage machines somewhat regularly likely don't put too many hours on the thing. Some parts will fail and fewer and fewer working examples of any given machine will be around as time goes on, but I don't think it's...
  10. J

    SE/30 screen distortion when HDD/floppy activity

    It's hardly surprising. The SE was an expensive high end machine, the top of the line compact Mac when it came out. The Classic was a cost reduced consumer machine, bottom of the line, cheapest Mac available when it was released.
  11. J

    Macintosh Plus problems

    The power switch is on the primary side, so pulling out the power cord is exactly the same as turning off the power switch. No need to fear the high voltage, it's not necessary mess with the anode connection to the tube to work on the analog board unless you have to completely remove the board...
  12. J

    An Idea, header + epoxy = easily replaceable cap

    If you're worried about tantalum capacitors failing, there are multilayer ceramic capacitors that will work, they're about 2x the cost but they are extremely reliable. They use this stuff in military equipment and satellites, just how reliable do you need it to be? Either way it's splitting...
  13. J

    An Idea, header + epoxy = easily replaceable cap

    That's a lot of work and additional potential failure points to avoid a bit of soldering every 20-30 years. Modern capacitors are better than the old ones ever were, and while tantalum capacitors *can* fail, as can chips and transistors and anything else, but they're certainly not a wear item. I...
  14. J

    Original 128k - With a twist... (PIC INTENSE!)

    EVERYTHING mac related cost a fortune back then, and people did upgrade old machines even when it was only marginally cheaper than buying a whole new one. A lot of those CPU upgrade cards were pushing up on $1500 throughout the 68K era. I always thought it was funny when people scrape the...
  15. J

    VACUUM FORMING ACRYLIC: First failed . . .

    Back in jr. high my shop teacher built a vacuum forming machine. He made a box with a platform made of pegboard with a lever that would raise and lower it and a shop vac to provide the vacuum. The lid was a sheetmetal box with a heating element from a clothes dryer (I think) stretched out and...
  16. J

    Oscilloscope 101 - Probing the bus for activity

    In schematic drawings, it's common for representations of parts to be laid out logically rather than to mimic the physical layout of the part. For example all the data bus pins might be grouped together in order, all the address bus pins in another group, the power and ground pins in another...
  17. J

    SE/30 screen distortion when HDD/floppy activity

    That isn't normal. So you re-capped the power supply? You might try cleaning the connectors between the power supply and analog board and between the analog board and motherboard. Also check for cracked solder joints on the analog board. This sounds like you might have a poor ground connection...
  18. J

    Caps! - Temp Controlled Soldering Irons - On A Budget!

    IMHO the Hakko stuff is better than Weller these days anyway. I always liked the 936, although it looks like they've discontinued it now. They sure did change to a weird color scheme on the new products.
  19. J

    SE/30 Recap - my first one!

    I was concerned about that, but I was surprised to find that the power consumption and even more importantly, the noise level of some of the drives is not too bad. There are two that I'm using, one is a Fujitsu 15K RPM drive which is a 3.5" form factor with 2.5" platters. It has fluid bearings...
  20. J

    Philips hue

    I found a teardown for those who are curious about the guts & gore. http://friendfeed.com/herf/f556fabb/philips-hue-bulb-teardown?embed=1 I haven't seen a Hue in person yet, but I can vouch that the other Philips LED bulbs are fantastic. The L-Prize winning bulb in particular is amazing...
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