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View Full Version : Got a little package from Digi-key tonight....



PacMan
January 27th, 2009, 11:10 AM
http://www.x-game.se/images/s100/motherboard.JPG

So I know exactly what I will be doing this weekend.. :frankenstein:

NobodyIsHere
January 27th, 2009, 11:40 AM
Nice! What are the Digikey part numbers? Is that the Vector S-100 board?

Thanks and have a nice day!

Andrew Lynch

Druid6900
January 27th, 2009, 11:45 AM
I don't envy you soldering 1800 pins........

PacMan
January 27th, 2009, 12:45 PM
Nice! What are the Digikey part numbers? Is that the Vector S-100 board?

Thanks and have a nice day!

Andrew Lynch

Andrew, those are Sullins EBA50DRTH connectors. I had to get those because of the distance between the rows. On most connectors this is something like 6.35 mm's but the Altair motherboard uses a narrower type. Which of course doubles the price of the connector :sneaky:. The EDC connector I linked to in the other thread would be a better choice if one were to design a new motherboard.

The board is an authentic Altair Rev.D motherboard.... I know i am a heretic to assemble it and actually using it ;)


I don't envy you soldering 1800 pins........

*heh* 200 already done, now time for :shower:

/Pac

PacMan
January 29th, 2009, 10:25 AM
And there's another 200 :boom:

PacMan
January 30th, 2009, 02:11 PM
Yey, done soldering all 1800 pins. Now I only need to mount it into my Altair.

Druid6900
January 30th, 2009, 08:03 PM
Yey, done soldering all 1800 pins. Now I only need to mount it into my Altair.

Yeah, and you're using lead/tin solder, a new set of lungs LOL

PacMan
January 31st, 2009, 12:13 PM
Nops, only use unleaded, plus I have a good solder smoke ventilation system at my lab desk. Very important if you solder as much as i do.

Druid6900
January 31st, 2009, 02:41 PM
Nops, only use unleaded, plus I have a good solder smoke ventilation system at my lab desk. Very important if you solder as much as i do.

Apparently, there is some concern with "tin whiskering" when using the RHOS certified solder. There is a recent thread on it somewhere here on the forum that you might want to search for.

nige the hippy
January 31st, 2009, 03:31 PM
Use leaded solder where possible, the lead-free has a nasty tendency towards crysallisation (1800 joints later, sorry!) The major problem with the fumes from old solder was the colophony resin (rosin) which causes bad reactions in asthma sufferers (me included).
The problems with lead are (some, slow) leaching when it gets landfilled. Someday I hope that no electronic goods get landfilled (that would have been the right approach in the first place) , and we can start using lead again, it's streets ahead of the modern alternatives (AFAIK they still make safety-critical stuff with leaded solder)
Thanks for the part number, I didn't know it was still possible to get S100 edge connectors. (Drool!)

PacMan
February 2nd, 2009, 03:28 AM
Aaahh, the good old fear of unleaded solder and soldering. I have been using unleaded solder products for about 5 years now and I have never (so far) had any problems. Neither with my hobby stuff or the professional stuff that my company produces.

Anyhow tin whiskering is, as I understand it to be, something to be concerned of in environments where the solderjoint is subjected to physical stress, which could be a concern for the backplane with repeated insert and extraction cycles of boards.

But as I said, I am not going to worry about it and I will be continuing to use lead-free solder ;)

/Pac

computer_recovery
February 2nd, 2009, 05:44 AM
:oha: Yup that looks like alot of work...Had to scrap one of those boards (backplanes) not to long ago.Came through the shop in a box of misc. damaged boards.

mosfeat
February 2nd, 2009, 08:35 AM
Few comments lead-free soldering that may be of interest.

Whiskers: This has been a problem long before lead-free solder, in the form of tin plated surfaces (boards and leads). Lead free directives have increased the prevelance of whisker problems by increasing the use and quantity of tin in platings and solders. Lead, itself, is considered to be a retarder of growth (probably by encapsulation and bonding). A good solder mask registration can also help by keeping joints separated. Brighteners, compromised surfaces and low temps (retarded growth above 90 degrees) appear to contribute to whisker growth. As a side note, zinc and antimony also whisker.

Whiskers generally grow to less than 1mm, but have been found grown to several mms and in rare cases 10mm. Thus, DIP and .1 center components are generally less susseptible to whisker growth than surface mount and fine pitch devices.

Solder Joint Integrity: Lead-free solder joints have been shown to be more brittle than leaded joints, both in the solder itself and in the bonding to the board [or other surfaces]. Flexing of the board and rapid temperature changes will lead to joint failure much more rapidly and to a higher degree with lead-free solder joints than with leaded joints. Heavier boards and more robust mounting is often recommended where lead-free joints have been used on large compression connectors. See below for additional joint information.

Increased Solder Temps: Lead-free soldering (with a few close exceptions) requires higher temps than leaded soldering. Higher temps can damage devices not designed to accept the increaded temp profile, and can also cause incomplete solder joints if the heat is taken away too quickly or the joint is cooled too quickly. This is all true for leaded solder, but more of an issue with lead-free soldering.

With the higher heat requirement, the time-on-heat must be reduced for non-compliant components to stay within the thermal profile, this can lead to poor quality solder joints, especially with large joints. Pre-heating and good fluxing with the appropriate flux can help make a good joint more quickly (leaded or lead-free). Rapid cooling, as a mechanism to keep within a thermal profile, can lead to a brittle and incomplete joint if the solder has not completely flowed and the flux not come out of the joint completely.

Effects on older DIP and .1 components? Whiskers are less of an issue given the spacing than with finer pitch components. Joint integrity I would worry about a bit both from a flex point of view and a heat/cool cycle. With pre-heating and decent technique, the higher temps shouldn't bee too much of an issue given the size of older components.

Personally, I still use lead on old repairs because it is easier to work with and the finishes on older components were made to work with leaded solder. If you want to go lead-free and are concerned about heat or compatability, there are rework formulations available that match the temp profile and characteristics of lead-based solder more closely than lead-free solders do.

PacMan
March 4th, 2009, 08:52 AM
And here's the result.

http://www.x-game.se/images/s100/New_mb_1.JPG

And

http://www.x-game.se/images/s100/New_mb_2.JPG

The old motherboard was turned into a S-100 lab system using an old Z80 S-100 board, a 16KByte Econoram 4 board and a tweaked DC/DC power brick. Pictures of that will come as soon as the battery in the camera is recharged.

/P

pontus
March 4th, 2009, 09:29 AM
impressive! good work.

chuckcmagee
March 4th, 2009, 09:54 AM
Pac, I see you have your SOL S-100 bus probe card installed!! Good good. I have mine sitting 7 feet away on a extender board. I WILL get that blankety-blank Northstar Horizon to boot up off of double density diskettes, if it kiills me. Looks like it might. Altho, I have one lone single sided diskette that came still in the drive that will boot up. Still waiting for a floppy controller that works. I have 4 of them sitting here that don't.

PacMan
March 4th, 2009, 01:18 PM
I have a Northstar Z80 board in my Monstera computer. Really neat with a place for a ROM on board and a programmable startup vector and all. Works like a charm.

/P