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lowlytech

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  1. lowlytech

    Simple file sharing (Mac SE/30 to Mac SE)

    I know my SE/30 had about 4 bad traces from capacitor goo that went to the printer ports. I was looking for some kind of loopback tester hardware for the printer/modem port but didn't come up with anything. Since then I connected up another mac and tried the file sharing between two macs and it just worked without doing anything special.
  2. lowlytech

    800k Floppy drive question

    The limit switches at the front of the drive, make sure they don't need a spray of deoxit maybe. I don't know for sure, but I figure one of the switches is to tell the system a disk has been inserted. Otherwise I know all the drives I have gotten needed disassembled and relubed. Just followed these instructions for the drive from my SE/30 and it is now working great. https://wiki.68kmla.org/Floppy_drive_lubrication
  3. lowlytech

    Need help hunting the other end of a trace on a SE/30

    The culprit was UD8, pin 4 to the Glue chip, pin 77. Everything else seems fine, as this was the only wire I had to run an now it comes up normal looking. I even got the original 40MB Quantum drive un gooed and it appears to be working without issue for the moment. Thanks again for all the direction and help with this. I appreciate it.
  4. lowlytech

    SE/30 logic board foreign object?

    What are the odds of that getting stuck right there. crazy..
  5. lowlytech

    Need help hunting the other end of a trace on a SE/30

    Awesome, Thanks Bolle for the heads up on where to look. One question which will probably echo macclassic's question. In this section of the schematics it looks like the Ux8 chips are listed twice. I assume this is just for each side of pins? Also say UA8 for example. Pin 5 just goes to nothing and says VADR (7). Where would I try to find the other end of this connection?
  6. Got the logic board recapped and reinstalled and apparently the resoldering of the flyback clip was successful. I have a display. The CRT acted completely dead without a raster or even light light up without the logicboard connected. This is probably basic mac knowledge, but I didn't know this. Slowly learning the ways of the vintage mac.
  7. lowlytech

    Need help hunting the other end of a trace on a SE/30

    Got the board recapped and looks like I still have broken traces somewhere. I get the startup chime but otherwise it;s WYSIWYG..
  8. lowlytech

    schematic question SE/30

    Had a quick question on the last traces I have to repair on my se30. On RP2 Pin 13 I get continuity on R41, but I do not on UD12 Pin 18. On RP2 Pin 17 I get a beep on R42 but not on UC12 Pin 2. Same thing with RP2 pin 18, I get a beep on R43 but nothing on UC12 pin 1. The fact that I get a good connection between RP2 positions and the resistors on the back of the board, where could the break be? Inside the boards layers? Should I go ahead and run wires from the RP2 pins to UC/UD pins even though the resistors are showing good continuity?
  9. Well I managed to get a complete analog board off ebay for a flyback replacement. I noticed on this analog board I got today that the wire in the cap is wrapped around a screw. The original flyback was just a wire soldered to the clips. I would just cut and splice the wire on the original one, but the molded cap plus the fact that it is 25k+ volts scares me to say the least.
  10. Just got the power supply and analog board completely recapped and was reassembling it when the darnest thing happend. I was putting the flyback plug back on the CRT and the little teeth or hooks that connect under the suction cup just fell out on the bench. There was a very small bit of wire present still in the cup, so I tried to dab some solder in there and reconnect, but now because of the tight space I have managed to blacken the area inside the rubber ring and can't really tell if I have indeed soldered the main cable back. I tried to ohm out the clamp to any of the pins on the transformer, but I get no beeps on the meter. I would just see if it turned on, but I still have my logic board without half of its caps and a few other items completely un-soldered from it. I went ahead and turned on the mac to see if I would see a raster or some sign that the CRT was indeed powered on, but it was completely dark even when fiddling with the brightness control. The neck of the tube did have the orange glow but I thought I would ask on a hunch if you powered on a compact mac with its logic board removed, what behavior does the CRT have? Thanks and hope I didn't just break my flyback, as I don't know how to strip more wire, as it looks to be completely molded to the suction cup.
  11. lowlytech

    SE/30 RP12 replacement part, bourns filter

    Found this reference that matches the datasheet that has capacitors inside the filter. http://jerome.vernet.pagesperso-orange.fr/SE 30/Repair Mac.html#NoPointer The mouser part I ordered 652-4120R-601-250/201L definitely does not test the same for resistance and/or capacitance from the original yellow 115-0002; c 5SB filter that was there, assuming the original part is still good.
  12. lowlytech

    SE/30 RP12 replacement part, bourns filter

    I take it that the L vs LF on the part number 4120R-601-250/201 should be an okay substitute? The last post from that thread was in 2013. Throughout that thread it sounded like they had some issues locating stock. The 2nd post shows a datasheet with capacitors within the filter. I am not seeing this on the current datasheet, however the part numbers seem to indicate the same chip. I think I will end up installing a 20 pin DIP socket and that way I can easily swap the chip, assuming the one I have now won't let the magic smoke out of the board.
  13. lowlytech

    SE/30 RP12 replacement part, bourns filter

    Well not sure what is different, but the original filter I pulled now tests 44.8~45.2 ohms across all the pins except the four on the ends which are common ground. The new filter I got today (4120R-601-201L) tests 50.0 ohms across, with the same four pins on the corners as a shared ground. Will 5 ohms make a difference in this application? I guess I could put the original filter back in, but after trying to clean it up the legs are still pretty much tarnished with green/black. One other thing, mouser lists this as 20 pin 200ohms. Am I measuring wrong since I only get 50 ohms?
  14. lowlytech

    SE/30 RP12 replacement part, bourns filter

    I do recall in my google searching, running into a post somewhere that showed someone subbing a 16 pin filter for the original 20 pin one. That or maybe apple themselves changing to a 16 pin later in the SE's lifetime? So is this filter just a resistor network, or is it suppose to have capacitors in it as well? The original filter I pulled out shows typical ohm readings on the middle most pins, but a few act like something is discharging as the value fluctuates.
  15. Couldn't find a general section for this question so since it was an SE30 thought I would post here. I have about 8 or so traces that still appear to have the protective layer on them and they do ohm out okay, but the trace is corroded looking underneath. What is the proper way to handle this? just make sure you soak the board in a mild acid to neutralize the cap goo, or do I need to take off the protective layer to clean the trace before re-applying with an overcoat pen? Just don't want to overthink or do unnecessary things that might end up causing more damage.
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