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LaPorta

SE/30 Logic Board Resurrection

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58 minutes ago, LaPorta said:

I have pretty good hot iron skills, and I was wondering if it is possible to use solder wick to suck out each traces solder and remove the chip. Tedious, but I would do it. If you guys really don't recommend it, I guess I'll bite the bullet and get the hot air station.

I have been able to remove surface mount ICs with just my soldering iron before, but I wouldn't really recommend it. On several occasions where I have tried this, several pads ended up tearing from the PCB. I now use one of the cheap 858D hot air stations, and I have had much better luck removing ICs with it instead. It took me a fair bit of practice to get the hang of using the hot air station, but once I figured out what I was doing, I had far greater success.

 

I'd recommend watching several tutorials and practicing on a junk board before trying to do anything to your SE/30 -it can be very easy to melt things by mistake and accidentally cause new problems.

 

Good luck!

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9 hours ago, archer174 said:

This!  I use ChipQuik all the time to remove SMD ICs and it works great. I’ve never lifted a pad.  

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Thanks for the suggestion! I may give this a go. If I do go with the hot air station, which would you guys recommend? There’s a ton out there with a huge price range. Also, I don’t need a station that has an attached iron, since I’ve got a nice hakko station.

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I use a very cheap 858D hot air station. (There is not an attached soldering iron) It looks like they cost about $40USD online right now.

 

From what I have read online though, it looks like there is a wide range of quality control depending on which seller you purchase from. The first thing I did when my unit arrived was to take it apart and make sure that it was wired correctly. (I was lucky enough not to have any issues with my hot air station) There are many videos online explaining what to check for and potentially change in the wiring so that the circuitry works safely and does not start a fire. I think I used this one: https://www.youtube.com/watch?v=pgR7YbXUivs

 

Other than the potential for safety issues, (which can be easily fixed if there are any) I have had fairly good luck with my station and I've used it to desolder at least a dozen components from my battery damaged Mac Classic's motherboard alone.

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Update: I got the 858 iron as well as nozzle for the chip. Nice little package. Worked well too. I’d say the replacement was not so bad as far as my first try with removal and then resolder with regular iron:10E87648-5479-46F8-986E-29E290349E9E.thumb.jpeg.3791ddf5e0bdb0cecafde34edb3a6cd3.jpegC78648FA-70BE-4DF7-A325-B4F0BDF497BB.thumb.jpeg.b6ab4160832269d189f434649dace4fa.jpeg

 

I fries the SCSI connector plastic a bit: will learn next time to cover it with foil or something.

 


The positive is this: the machine now starts from a floppy! The old chip must have indeed been fried from past carelessness. However, I can not locate the internal drive in the bus, and it worked the last time I had this thing fired up. There may yet be some kind of issue, I wonder where to look next...

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I tried this morning with a known-good SCSI HD, to no avail. Using Apple HD SC Setup from a floppy freezes the machine. There must be some other error somewhere (diode, resistor, etc) along the chain that is likely causing something, but I don't know where that might be. I'll look at the schematics and see if there is anything obvious.

 

Suggestions always taken, as usual.

 

Also, is it rather easy to get replacement 50-pin SCSI headers if you really mangle them with heat?

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Might still be a bad trace.

What traces did you check in the beginning? Everything that comes and goes to the SCSI chip?

Also make sure all your soldered connections are good.

Most of the time when it does the no :?: thing it is one of the data bus data lines that’s not connected to the chip.

When one of the SCSI data lines is broken you get the HDD light flashing at the same rate as the :?:

 

Edited by Bolle

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To be more specific, Bolle, it originally had the gray raster and no question mark problem. Now that I replaced the SCSI chip, the question mark comes up normally, and I can boot with a floppy, no issue. So, in effect, the SCSI chip works now as the machine can communicate with it...but SCSI itself is not working properly.

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