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at0z

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  1. Thanks for the post drag wicking tip - just seen someone doing that. I tend to use gel flux but I'll give the paste a go. Any preferred tip type for the drag ?
  2. Would anybody care to share their top tip(s) for replacing the packages like the SWIM and VIA ? The curled under pins make it very easy to create a bridge that you can't see, at least from my examples. I've seen YouTube videos where the pads are cleaned back completely, flux is added, the package is placed in position (much easier to do with no solder on pads) and then solder paste is applied and hot air used. Others appear to start with bare pads, add flux, tack a couple of pins to anchor the package then drag solder each side (that seems to be a prime risk for bridges though). Fi
  3. I think the VIA may be hosed - I'll try one from a donor board. Got to keep feeding the slot machine for a payout...
  4. Thanks, I also just spotted the mysterious white dot on the PCB screening....
  5. I feel better knowing I'm in good company Question on pin numbering - on some of the quad packages, it seems pin #1 is halfway down one side rather than the corner - I don't see anything in the schematics stating which chips do that - is there a listing somewhere of which ones play that game ? At least that might give me an idea whether the couple of bridges were in a major danger zone...
  6. Well replacing Q16 was interesting but ineffective at resolving the wild swings in power draw. Couldn't see any pin shorts on the video or SWIM or SCSI. As the SWIM was already off the board, I decided to pull the video chip which was fun. But it was worth it - underneath the chip out of sight were a couple of solder bridges. Unfortunately didn't note the pin numbers off hand, but cleaned up the pads and the board now draws an expected voltage and current. Got the video chip reunited with the board (those overhangs are a challenge - do most folks use a curved tip on the iron or sol
  7. Fixed up the display which had vinegar syndrome. Many of the cables still unopened. Oddly the one 68k machine which doesn’t seem covered is the original Portable, or did you need to choose something like the SE for testing?
  8. that’s an infrared of Q16 showing the temperature after about a minute with power on. I didn’t do any rework around the power side of the board, just SWIM and SCSI packages. Of course as most things there could be multiple layers to the onion. I pulled Q16 and the wild fluctuations went away which suggests to me nothing upstream is shorting but.... going to replace it and see...
  9. Hmmm so Q16 is getting warmer/hotter than I would expect (I saw it reach 150F) - does that suggest it may be faulty or it's just running hot trying to manage the voltage swings ? Q14 and Q15 although I see swings on voltage there do not appear to be toasty... It's fairly early on in the power schematic if I read it right...
  10. Pulled the SWIM but the power fluctuation madness is still there. Guess I need to track that down first. Hopefully the Hybrid hasn't blown its brains out...
  11. Well curiouser and curiouser said Alice... Ran a soldering iron around the SWIM and SCSI and VIDEO packages just to see if there was a bridge or dry joint. Connected power and the voltage and current is all over the place and PMGR reset has no effect, Q16 gets hot. Not my bench supply as another gave the same results. Guess it’s one more demon to exorcise. 4FC88E4D-5D56-4FEC-BACC-82E46748795C.MOV
  12. Thanks! I figured I would look at both the SWIM and SCSI packages. Which controller do you mean - the Video one ? I also see another Sony brand SRAM close by and I assume that's the VRAM. Will also look at that. I'm not giving up on it yet
  13. Went back over any suspect joints and one step passed, no more Sad Mac error or chime. Now getting pointer in top left but no flashing question mark and my SCSI2HD external doesn’t show any signs of access nor does floppyemu. The striped display changes and clears. Looked for hotspots on the board but oddly the two sound chips are the warmest (sound left & right). I’ll have a look at the video vram side next but if you’re familiar with the pattern changes, please chime in... 93A678A8-D5F7-47D0-B798-0BED5EFF2EB0.MOV
  14. New RAM finally made it through the quagmire of postal parcels, soldered on and now getting Sad Mac straight away data bus or RAM. Not sure how to decode the minor error. I’ll go back and recheck my work, here’s the code in case someone has a eureka moment
  15. Acquired a Techstep kit virtually unused (cables still sealed) but the display was foggy dark so the seller cut me a deal. Took it apart after researching vinegar syndrome and the sniff test confirmed my expectations. Removed the old film which looks like bad sun tint and replacement film should be here in the next few days cost $9. Many devices aren’t around after 30+ years to notice the syndrome but in case it helps anybody else...
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