Dove MacSnap restoration - broken pin

[tanaquil]

I was going to keep all my compact restoration questions in one thread, but then I thought it might be easier to get answers if I break them up.

As mentioned in an earlier thread, I have a 512K board upgraded with snap-on RAM and SCSI boards, I think both from Dove MacSnap. Either it or the analog board (or both) were not working when I pulled them from a non-working 512Ke some fifteen years ago. Picture of all three:



Can I put these boards in the dishwasher without removing any RAM or ROM chips? The RAM is soldered on and the ROM is socketed. They are really dusty and cleaning with alcohol and rinsing lightly definitely didn't remove all the gunk.

Sadder news:

While trying to straighten the pins on the SCSI board (the ones that plug the ROMs into the socket below) I managed to break one off and it went flying (so I don't have the pin to solder back on). Second row from the bottom, second pin in from the left.



Is this fixable? What, if anything, could I do to replace the missing pin? I don't care that much about SCSI on this machine but not knowing exactly how the upgrade worked, I am not sure what to do to undo it apart from moving the socketed ROM chips back onto the main board. I don't even know how much memory this was originally upgraded to - if it has the SCSI maybe it has 1 MB? Strangely, I see no sign of a SCSI cable having been run to the outside of the machine.

I don't have any grand plans for this machine since it has never been working since I got it, but I thought it would be fun to get it back into working order.

 

[Dog Cow]

Is this fixable? What, if anything, could I do to replace the missing pin? I don't care that much about SCSI on this machine but not knowing exactly how the upgrade worked, I am not sure what to do to undo it apart from moving the socketed ROM chips back onto the main board. I don't even know how much memory this was originally upgraded to - if it has the SCSI maybe it has 1 MB? Strangely, I see no sign of a SCSI cable having been run to the outside of the machine.

Fixable? Yes. I have a couple of ideas floating in my head, but I'll keep quiet for now, and let someone else answer first.

You have a 1 MB MacSnap-- when that large board is installed, your Mac 512Ke has 1 MB total RAM. The SCSI and RAM upgrade can be installed separately or together. Neither one depends on the other.

With both the RAM upgrade and SCSI board installed, in addition to the 800K double-sided drive that is characteristic of the 512Ke, your 512Ke looks like a 1 MB Macintosh Plus to software, and effectively is a Macintosh Plus. With a 2 MB MacSnap+SCSI, you can run System 7 on your 512Ke, which I think is really wild! :-0

 

[tanaquil]

@Dog Cow, since no one else has weighed in on the broken pin so far, what are your ideas?

I washed all the boards in my dishwasher (the Dove MacSnap parts turned an odd shade of green on the underside but appear otherwise unharmed) and have been leaving them to dry for almost a week since their initial drying session in the oven. I put the ROMs back into the original motherboard and plan to test it bare (without the RAM board or SCSI) in a working bench machine first before I try out the Dove stuff. Not sure it will work as some adjustments might have been made on the motherboard to accommodate the extra RAM - I will see!

 

[Dog Cow]

Get a really small gauge wire. Solder one end to where that missing pin should go (not necessarily there on the bottom, but could be on top of the daughter board), then solder other end to the appropriate point on the ROM socket on the Mac logic board.

 

[Gorgonops]

The right way to do it would be to buy some new male machine-pin header strips, desolder the old strip, and replace the whole row. (They're a standard thing and not too hard to find, here's a link:

http://www.king-cart.com/phoenixent/product_name=HWS16333/

Note I don't recommend this vendor in particular, I picked the hit from the first page of Google image searches that matched what you have there most closely.)

The downside is, I'm guessing, that this would be a pain in the neck (It looks like there are ROM sockets preventing you from getting a soldering iron to the far side of the board?) *and* that if you buy a random set of header strips today there's a good chance the insulator block and pins will be a different height than the ones that are on there. If they were a little shorter it probably wouldn't be a big deal as long as the pins are long enough, I guess.)

The other alternative would be to try to desolder *just* the base of the pin you broke off, try to extract it from the plastic holder, and solder in another pin assembly. That would be *really* hard to pull off; getting *all* the solder cleanly off the one pin so you can manhandle pulling it out of the plastic thing like an angry molar *without* damaging the socket via on the board would be... annoying. Probably in the end more annoying than doing the whole strip, *unless* it let you get away with not, say, having to desolder the ROM sockets on the other side.

Edit: Third bad idea I have would be to try drilling out the base of bad pin enough to solder a new pin stolen from a new header strip (or even just a chunk of lead from a discrete component, like a resistor.) If you have a drill press, tiny diamond bits, and nerves of steel it could be worth a shot.

 

[360alaska]

This: https://www.ebay.com/itm/10Pcs-Gold-Plated-2-54mm-40-Pin-Single-Row-Straight-Round-Pin-Header-Strip-FJ/142808030530?hash=item2140059d42:g:dGUAAOSwVY1ZndcE

 

[tanaquil]

Thanks for the suggestions everyone! I may need to save this SCSI board until my soldering skills are a lot higher level. Sigh... it was in great shape until I fumbled and dropped it on the floor. 

I am am glad to know I can reinstall the RAM board without the SCSI in the meantime. 

ETA: given my low level skills desoldering the whole strip sounds safest. I just ordered a cheap hot air station, would that help, or just make things messier?

 

[360alaska]

Be careful with hot air, in the wrong hand you can overheat/delaminate the board.

 

[tanaquil]

I really should have bid on that lot of random circuit boards that just ended on eBay. Maybe they’ll relist. I need SO much practice. 

 

[olePigeon]

I have the exact same upgrade, and I had a couple pins break on mine, too.  Same connector.  I desoldered the whole connector and put on a new one.  The part that 360alaska linked to will work.  You can use a razor or clips to cut it to length.  It's easy, but can be laborious.  The old solder doesn't like to melt.