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Help Buying Parts & Building XT-IDE Rev2 & Lo-Tech ISA CF

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wesleyfurr

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Joined
Jul 16, 2009
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Location
Virginia, USA
I'm hoping someone can give me a few pointers... I have in my hands an XT-IDE Rev2 board, along with two of the Lo-Tech ISA Compactflash boards, which I want to assemble! Or at least try...

First question is in regards to buying the necessary parts. I'm in the USA, so the Farnell parts list on the Lo-Tech board isn't as easy and placing an order...at least not without paying a very hefty shipping price! And for the XT-IDE Rev2, I'm finding some of the Jameco parts discontinued, or seemingly cheaper at Mouser. Are all the little IC chips as generic as they seem to be? Stuff like the 74LS04, SN74F573N, etc? Part numbers seem to vary ever so slightly, such as the 74LS04 being listed as an SN74LS04... I just don't know enough about those types of parts...and I don't want to buy the wrong thing and have to re-order, or run into problems after I spend a pile of time soldering. :) I've also tried to find some equivalent parts at Mouser other than from the Jameco list on the XT-IDE Rev2...a bunch of those were minimum quantity of 10, which would just go to waste for me. At least I'm assuming I have found equivalent parts...mainly DIP sockets. I'm also planning to put the chips in sockets on the Lo-Tech board, as I don't trust my soldering enough yet to solder them direct.

I have created a spreadsheet of what parts to buy where, if anyone wants to have a look, I can send it to you...didn't seem to want to allow me to attach a .XLS file to this post.

And one other question...when it comes to soldering, flux, cleaning, etc, what do you guys recommend? I've done a fair number of repair type solder jobs, mainly replacing failed capacitors...but have never bothered to clean up the flux. Does that really need to be done with these boards when I am done? If yes, what do you recommend? And should the empty boards be cleaned prior to beginning?

Thanks!

Wesley
 
wesleyfurr said:
I'm hoping someone can give me a few pointers... I have in my hands an XT-IDE Rev2 board, along with two of the Lo-Tech ISA Compactflash boards, which I want to assemble! Or at least try...

First question is in regards to buying the necessary parts. I'm in the USA, so the Farnell parts list on the Lo-Tech board isn't as easy and placing an order...at least not without paying a very hefty shipping price! And for the XT-IDE Rev2, I'm finding some of the Jameco parts discontinued, or seemingly cheaper at Mouser. Are all the little IC chips as generic as they seem to be? Stuff like the 74LS04, SN74F573N, etc? Part numbers seem to vary ever so slightly, such as the 74LS04 being listed as an SN74LS04... I just don't know enough about those types of parts...and I don't want to buy the wrong thing and have to re-order, or run into problems after I spend a pile of time soldering. :) I've also tried to find some equivalent parts at Mouser other than from the Jameco list on the XT-IDE Rev2...a bunch of those were minimum quantity of 10, which would just go to waste for me. At least I'm assuming I have found equivalent parts...mainly DIP sockets. I'm also planning to put the chips in sockets on the Lo-Tech board, as I don't trust my soldering enough yet to solder them direct.

I have created a spreadsheet of what parts to buy where, if anyone wants to have a look, I can send it to you...didn't seem to want to allow me to attach a .XLS file to this post.

And one other question...when it comes to soldering, flux, cleaning, etc, what do you guys recommend? I've done a fair number of repair type solder jobs, mainly replacing failed capacitors...but have never bothered to clean up the flux. Does that really need to be done with these boards when I am done? If yes, what do you recommend? And should the empty boards be cleaned prior to beginning?

Thanks!

Wesley
Click to expand...

Hi

There is a lot of flexibility regarding the part selection on XT-IDE V2. As long as you keep with TTL type chips you should be OK. I recently discovered an incompatibility using 74ALS245 chips on my ancient original IBM PC (5150) test computer but it is the first I've heard a part substitution causing problems. I suspect had I used a more recent machine the 74ALS245 would have worked just fine and it is a symptom of the original 5150's flakey bus design more than anything.

What I recommend is just build your parts list/BOM and post it here for community review. If anyone finds issue with your choices hopefully they'll speak up. Put it on the wiki or post a link from somewhere else to the spreadsheet.

Regarding flux removal, I would chip off any excessive flux build up with a toothpick during the post-assembly inspection. For the most part leaving excess flux won't cause problems with low speed TTL devices like XT-IDE V2. Flux might be an issue for faster circuits but I doubt it. Although I do have some flux remover I rarely use it since it is toxic and the boards smell bad afterwards. If you use flux remover then do it outside with good ventilation and leave the boards outside for a few days to out-gas.

Good luck. The best advice I can give you is to ask your questions here and post your plans *before* you do anything. Community review will save you tremendous pain. Use the VCF search function! Thanks and have a nice day!

Andrew Lynch
 
Andrew,

Thank you for your help. In looking at the Jameco parts, it certainly looked like many of the IC's were very generic parts...but I haven't worked with them enough (at all!) to know.

I uploaded the spreadsheet to http://www.megley.com/temp/xtideparts.xls I highlighted in yellow the part number and price of where to buy each line item. The upper section is the Lo-Tech parts build (not bothering with the slot 8/LED SMD parts on the back), the lower is the XT-IDE Rev2. Any input is appreciated...

My main concern with the flux is people saying that supposedly it is corrosive over time? I don't really care what it looks like so long as it works. :)

Thanks,

Wesley
 
wesleyfurr said:
Andrew,

Thank you for your help. In looking at the Jameco parts, it certainly looked like many of the IC's were very generic parts...but I haven't worked with them enough (at all!) to know.

I uploaded the spreadsheet to http://www.megley.com/temp/xtideparts.xls I highlighted in yellow the part number and price of where to buy each line item. The upper section is the Lo-Tech parts build (not bothering with the slot 8/LED SMD parts on the back), the lower is the XT-IDE Rev2. Any input is appreciated...

My main concern with the flux is people saying that supposedly it is corrosive over time? I don't really care what it looks like so long as it works. :)

Thanks,

Wesley
Click to expand...

Hi
OK Thanks! I'll give it a review later tonight.

Regarding the flux issue. Maybe it can get corrosive over a long enough period of time depending on conditions like humidity etc. More likely it will oxidize and turn white and just look crappy. Remember between the flux and the PCB is a solder mask which is tough as nails. It certainly is not going to hurt the solder itself.

You can literally wire brush the back of soldered PCB to remove excess solder without damaging the traces. Solder mask is really tough stuff. Of course it will probably look as bad as the excess flux did afterwards.

Any way you go there are problems. You can use flux remover but just be sure to clean the PCB or let it dry out properly including the sockets, components, etc. Otherwise I find they smell funny with a solvent like odor. I just do a compromise and pick off the worst of the flux blobs using a toothpick. That eliminates almost all of it since the flux easily chips right off once it dries and hardens.

I've got some old S-100 boards from the late 1970's with excess flux on them that look relatively new decades later. They work fine. Many of the older S-100 PCBs were literally hand assembled before the machine assembly factories took over.

In the big scheme of things, excess flux is not that big of an issue. It is mostly cosmetics although there is some grain of truth (capacitance, corrosion, etc) in it is bad when you leave too much. The main reason to clear off excess flux in my opinion is to inspect the solder joints to prevent cold solder joints. Now *that* is a real problem and a real PITA down the road.

Thanks and have a nice day!

Andrew Lynch
 
Anyone have any thoughts? Hope I'm not being annoying by asking again...just anxious to get some parts in and start soldering... :) I even have a (hopefully) nice new soldering station here in the box ready to go.

Thanks,

Wesley
 
I use a Kester solder with an organic, water soluble flux core when I care about getting flux off. A minute under the running tap and a little scrubbing with an old toothbrush is all that is required.

A quality rosin core solder will use a flux that isn't corrosive. Kester 44 core is one such product. As long as you don't care about the look of the flux on the board, there is no need to remove it from digital PC boards, at least not at the speeds we're using. It can cause problems in analog circuits.
 
I hadn't heard back from anyone regarding the parts list, so I bit the bullet and put in an order. Hopefully all will work ok...

Of course right after I placed the two orders from Mouser and Jameco, and after thinking about any other parts I might could use...I then remember that I should have gotten some solder too. I have some who-knows-what that I've been using that came with a cheapy 30-watt soldering iron I got years ago. I thought I remembered having recently found a small Radio Shack spool of something, but if I did, I put it in a safe place where I now can't find it. :)

Anyway...does anyone have a recommendation about what to use? I checked out the Kester 44 as noted by Glitch, but it only appears to be sold (at least through Mouser and Jameco) in huge rolls...that would probably be a 10x lifetime supply for me. Does Radio Shack sell something suitable, non-corrosive, etc? I know I need rosin core, but what diameter should I be looking for, any specific %, composition, etc? What I've been using is kinda medium-sized and probably a little big for the fine-pitch work on these boards...

Thanks,

Wesley
 
I'm hoping to build up both of my Lo-Tech boards today. I'll let you know how that goes.

I got my parts from Mouser and Farnell. I sent James the part numbers which he said he added to the BOM on the Wiki, but I don't see it.

If you look on the Wiki, there are some construction tips below the BOM.

I won't be able to test them today as my XT is partway through a 640k mod. As soon as the RAM chips arrive and that tests out, I'll program both boards up and test them. I have both hard drives and a CF card to try with them.
 
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One of the capacitors I bought was wrong. It was not a surface mount. I'll have to get the right kind, though I could probably make this work.

I only have the one large socket for the memory chip, so I put that in both boards along with C1 - C5. I have most every other part, and I could skip the sockets... But, I think I'll wait for them to come in.

Soldering the board was very easy. No need to have major worries. The only hard parts are the optional SMD parts on back of the board. I wish I hs a bracket for this board, I'm going to hte having it floating around the case without being secured.
 
Al,

Thanks for the build report...that sets my mind at ease a bit. Since I don't care about the XT slot 8 compatibility and am not too worried about an LED, I opted to skip the surface mount stuff on the back. I also ordered sockets for mine...don't trust myself that much yet! As for the lack of a bracket, I've used a board or two in the past without one...and there's not really any way they can go anywhere...personally, I wouldn't worry about it too much.

What size and type of solder are you using? I need to get some...

And are you using a soldering station or just a regular pencil? I bought a YiHua 936 (a Hakko 936 clone) soldering station. What temperature should I be running it at? I took it out of the box last night for the first time to try to use it for desoldering leaky caps from a Mac LC motherboard...I really struggled to get it to put any heat to the tip. I'm concerned when I go to building the CF board that I won't be able to get heat close to the tip...though perhaps it will be different with new parts vs. ugly messed up ones from leaky caps. I know you are supposed to use the side...but I struggled even with that (it has a nice long sharp fine point compared to my old pencil iron). I cranked the heat up to try to compensate, but then it just oxidized the tip even faster. Is the right procedure for cleaning to add solder to the tip (as close as will melt), wipe, then repeat as needed?

Thanks,

Wesley
 
I'm using a Radio Shack 40-Watt Iron, and the solder it came with. It only takes a second or two for the connection to heat up and the solder to flow. I practiced on two PS/2 to Atari/Amiga adapter kits, and desoldering a socket from my Atari RAM upgrade and installing a new one.

It's not hard. I didn't need anything special. I have a solder sucker and braid standing by in case I use too much solder, but that hasn't been a problem. At the end, I'll wash of the excess rosin with a toothbrush and a little alcohol.
 
Sorry I completely missed this thread. Please do post back how your lo-tech build went.

The card is so small, really no bracket is necessary.

BTW, there is some problem with the very latest (R552+) BIOS on some platforms, including the 5160. I've not hsd chance to debug it yet.
 
Al Hartman said:
That's not helpful as I don't know what to do with that information.
Click to expand...

Ah, sorry. I assumed you knew how to make the BIOS since you asked for a specific revision number. In any case it's not hard, instructions are here. Just remember to edit out MODULE_VERY_LATE_INITIALIZATION from the makefile before building.

Hope this helps!
 
Nope, not going to build one. I'm looking for a pre-built BIOS I can use. So, what I'm asking is... What is the latest revision without the bug James mentioned?

I downloaded one last month. I guess I'll just use that.
 
Al Hartman said:
Nope, not going to build one. I'm looking for a pre-built BIOS I can use. So, what I'm asking is... What is the latest revision without the bug James mentioned?

I downloaded one last month. I guess I'll just use that.
Click to expand...

The latest official prebuilt release is beta3, however, a number of bugs have been fixed since then (one in the very latest revision, which is why I recommended that) so if you want to avoid bugs... ;)

Like I said, it's not hard to make the BIOS but if that's not an option, your best bet is to have someone make it for you. I would do it but can't due to hardware problems.
 
If there isn't a pre-built one available by the time I'm ready to flash mine, I'll have a try at building it and can share the results if you want... Just glanced at the directions, didn't realize it was so involved! But hey, I'm always game for a challenge. :)

Wesley
 
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