How NOT to Assemble The Altair 8800 Clone

General discussions related to the Altair 8800 Clone

How NOT to Assemble The Altair 8800 Clone

Postby MajorClements » October 10th, 2022, 10:13 am

Well, it has been about eight years since I purchased my clone. I am ready to admit my two big mistakes while I was building the kit. I was too embarrassed to bring this up in the beginning, I was more so worried about the criticisms than the actual honest answers—I had a lot of confidence issues when I was 14. Well, I’m 22 now, and I’m way more confident in myself, soldering, and asking for help when needed (Note: I had a look at the pictures, and I have gotta say it’s gonna be tough to look).

Issue 1) What the heck happened? It is not the fisheye effect. My front panel LEDs appear to retreat into the case toward the center; however, it looks almost flush on the sides. Looking back at the instructions, I think I may have missed the step where I was supposed to put one of those plastic spacers in between the front panel and PCB, to prevent "PCB sagging," but I don’t 100% remember. Also, there are a couple of solder joints that are not making a good connection to the front panel PCB, so the "INTE" LED and "A8" LED have to be jiggled to stay on. I think I fixed one of the LEDs already, back in 2015. I believe it was the "D7" LED.

IMG_3445 (1).jpeg
Here is the strange shifting effect of the LEDs, the second image is probably the source of this bend.


IMG_1103.JPG.jpeg
As we can see here, there is a noticeable PCB bend in the middle, so using the plastic spacers would have had to be a necessity.


I will be fixing the LED issues soon. Overall, it might just be easier to take out the front panel, desolder all of the LEDs, buy a whole 36-piece LED set, and redo it properly. That said, I don’t see why I can’t just skip that spacer step and just mount the LEDs loosely until the whole front panel is mounted in that L-Bracket. After all that, I could just push them flush into the front panel and solder each one as I go (hopefully the LEDs flange out far enough to catch). Reduced warping tolerances would be an absolute worst-case scenario for this method. I would like to hear everyone’s input, especially our leader, the good man himself, as well. Feel free, to be honest, I can take criticism. Also, if you have any advice, it would be most appreciated. Overall, my excuse for the butchered soldering job was lack of experience. I will add that I redid most of the joints in 2015, so they look a lot better now than when these were taken.

Issue 2) in 2013, my understanding of the RS232 was established to me from the physical connector rather than the protocol standard. I didn’t know that they were separate. This was one of my hardest gremlins to resolve after I finished the kit. I did not have the proper tool to wire together the RS-232 data cables and slot them into their Molex connectors—I didn’t even know there was a proper tool for them until about two years ago on a separate project for my car. I’m not quite sure if I had the wiring correct the first time I had the system set up, but I was definitely having intermittent connection problems due to my terrible “crimp” job.

IMG_1607.JPG.jpeg
Here is my big no no. I know, it is painful. I want to redeem this and the fix by getting a whole new set.


I don’t know why I thought this was a good idea at the time, but I decided it was better to solder all the male pins straight to the wires (bypassing the Molex connectors) going to the DB-25 connector on the board. In hindsight, alligator clips would have been just fine. Well, this did two things: it fixed the intermittent connection problem to the terminal emulator, but it made those male Molex pins thicker, so if I wanted to go back to the female connector, it would be next to impossible to slip back on. This was the case when I decided to reverse my mistake in 2015. That said, I will be replacing the connectors Male and Female, and possibly purchasing some replacement DB-25 connectors (I think I wired the port up like a Null Modem, when it should have been 1 to 1.

As an improvement to the overall experience, and to slim the wire clutter down, I was thinking of using a Raspberry Pi Zero W with an RS-232 Serial Port. That way, I could SSH into the Pi, then MiniCom into "/dev/ttys0," thus a wireless console. I will keep the back connector and just run one of those flat ribbon cables out the back to make it easier to switch between the Pi and a traditional console. I will make use of that "AUX" switch jumper for the ATX mod and use it to power the Pi off. I can probably write a quick script with Python.
Sincerely,
Daniel
________________________________________________________________________________
“THINK!”
If you had to remember only one thing about me, just know that I’m the guy with too many ThinkPads to count.
MajorClements
 
Posts: 18
Joined: January 30th, 2014, 9:18 am
Location: McLean, Virginia

Re: How NOT to Assemble The Altair 8800 Clone

Postby Wayne Parham » October 10th, 2022, 12:50 pm

What's totally awesome is that you jumped in with both feet. That makes it all a big win, in my opinion. Because you can always work through the issues you encounter - but only if you actually start - which you did. So kudos to you for jumping in with both feet!

On the connectors:

I would suggest removing excess solder with a solder wick. Buy about five rolls of solder wick and remove all the solder. Get a couple cans of flux remover too, 'cause after you're done desoldering and resoldering, your boards will be a mess. Work on each pin, one at a time, melting the solder and removing the wire. Then remove excess solder from the pin with a solder wick. Alternatively, you might want to use solder wick to remove and replace the whole Molex connector.

Be careful to let the PCB cool after each solder attempt. Do not hold heat to the board longer than about ten seconds at a time. We don't want to weaken the adhesive that holds the copper to the fiberglass. We don't want to damage the board.

After you've cleaned off all the connector pins (or replaced the Molex connectors entirely) then make cable assemblies with connectors and nice fresh wire.

On the PCB warpage:

It's not uncommon for a printed circuit board to warp, especially a long one. So, yeah, the board must be "clamped" as the components are soldered onto it. That's what those spacers do. They hold it in place.

I would suggest desoldering all the LEDs with solder wick. Take your time, simultaneously heat both leads of an LED and pull it out. If you don't have a chisel tip that spans both leads, get one. Best to use a Weller iron with a chisel tip for this process.

Pay attention to LED orientation, which is shown by a flat side. You may be able to reuse some or all of them. But some may have leads cut too short from the original assembly. No problem - LEDs aren't very expensive, so replace 'em if need be.

Once an LED is out, use the solder wick to remove excess solder from the board. That'll make it just like new, and once you've removed all of them, you can re-do the LED installation process, this time with a spacer to help get 'em all at a uniform height.

You're doin' great, dude!
Wayne Parham
 
Posts: 240
Joined: March 18th, 2022, 3:01 pm

Re: How NOT to Assemble The Altair 8800 Clone

Postby MajorClements » October 10th, 2022, 2:58 pm

Wayne Parham wrote:What's totally awesome is that you jumped in with both feet. That makes it all a big win, in my opinion. Because you can always work through the issues you encounter - but only if you actually start - which you did. So kudos to you for jumping in with both feet!

On the connectors:

I would suggest removing excess solder with a solder wick. Buy about five rolls of solder wick and remove all the solder. Get a couple cans of flux remover too, 'cause after you're done desoldering and resoldering, your boards will be a mess. Work on each pin, one at a time, melting the solder and removing the wire. Then remove excess solder from the pin with a solder wick. Alternatively, you might want to use solder wick to remove and replace the whole Molex connector.

Be careful to let the PCB cool after each solder attempt. Do not hold heat to the board longer than about ten seconds at a time. We don't want to weaken the adhesive that holds the copper to the fiberglass. We don't want to damage the board.

After you've cleaned off all the connector pins (or replaced the Molex connectors entirely) then make cable assemblies with connectors and nice fresh wire.

On the PCB warpage:

It's not uncommon for a printed circuit board to warp, especially a long one. So, yeah, the board must be "clamped" as the components are soldered onto it. That's what those spacers do. They hold it in place.

I would suggest desoldering all the LEDs with solder wick. Take your time, simultaneously heat both leads of an LED and pull it out. If you don't have a chisel tip that spans both leads, get one. Best to use a Weller iron with a chisel tip for this process.

Pay attention to LED orientation, which is shown by a flat side. You may be able to reuse some or all of them. But some may have leads cut too short from the original assembly. No problem - LEDs aren't very expensive, so replace 'em if need be.

Once an LED is out, use the solder wick to remove excess solder from the board. That'll make it just like new, and once you've removed all of them, you can re-do the LED installation process, this time with a spacer to help get 'em all at a uniform height.

You're doin' great, dude!



Awesome! Hey Wayne, nice to hear from you again!

I actually picked up a Weller brand new a few years back, I think I have the chisel tip. I found the temperature to be way more consistent than compared to the junk, no name one I bought from a local computer parts store. It lasted about half way through the assembly process and failed. It was hilarious! I had to borrow my dad’s. For some reason, solder wick has never worked properly for me no matter the amount of YouTube tutorials I’ve seen. That said, it is sort of my only option, as my desoldering station’s vacuum is not pulling a vacuum, I’m still working on that right now, but haven't gotten to it yet.

The Molex connectors are never going to be what they used to be, so I am alright with tossing them out for replacements. The pins on the female side are not properly crimped anyway, so It will be easier overall. As for Flux Remover, I’ve heard from friends that Isopropyl alcohol is a good substitute, I assume that would be fine for this situation?

Also, I sadly do not know where those special plastic spacers went, but I assume I can find them on line somewhere. I recall that Mike used a special brand of Red LEDs (Everlite HLMPD150), according to the 8800c), but I assume any red LED could work due to the nature of their design. I’ll probably ask Mike where he bought the serial port, plastic spacer, and related molex components.
Sincerely,
Daniel
________________________________________________________________________________
“THINK!”
If you had to remember only one thing about me, just know that I’m the guy with too many ThinkPads to count.
MajorClements
 
Posts: 18
Joined: January 30th, 2014, 9:18 am
Location: McLean, Virginia

Re: How NOT to Assemble The Altair 8800 Clone

Postby Wayne Parham » October 10th, 2022, 6:52 pm

Isopropyl alcohol will not remove the flux nearly as well as flux remover. So I would suggest buying some. It's kind of expensive, but it's worth it. Your boards will be nice and clean.

I've used both solder vacuums and solder wick. A really good desoldering station is awesome. The little "solder-sucker" bulbs, not so much. A good solder wick works very well. So maybe you got a poor brand of wick. Not sure, but I think it's worth trying again.

Try this: Get solder wick and flux remover on Amazon. Start with one roll of solder wick and one can of flux remover.

The links above are stuff I use often, and they work very well for me. The solder wick will make you laugh 'cause it's labeled "no clean" but believe me, you'll want to clean up afterwards. And that's good, because part of the reason it works so well is it has a lot of flux in it to help the solder flow. The other thing that helps is the wick's wire mesh is so fine it soaks the solder up just like a sponge.

Get a board that you don't care about. Flow some solder on it somewhere. Then rest the wick on the new fresh solder blob you just made. Place the hot iron tip onto the wick and apply light pressure. Gently push the tip onto the wick, which in turn is pressing onto the solder. Once it starts to melt, you see it soak up into the wick.

I find that sometimes old "crusty" solder doesn't flow up into the wick very well, but flowing a little fresh solder onto the joint helps get it to flow. Seems like the wick works better on fresh solder. So if you don't clear the circuit board pad on first try, flow a little fresh solder onto it. Cut back your wick to a fresh area and try again.

I also find that if there's a lot of solder to pull up, I need to move the wick along to keep presenting fresh wick, "wiping up" the molten solder. It's almost like using a paper towel in a large pool of water - once the area of towel is saturated, I have to bring in another dry area to soak it up.

So grab some old board, something you can "hack on" a little bit. Flow some solder into a joint and remove it with wick.

Do that a few times. Get a hang of it. Then go back to your Altair board and repair it.
Wayne Parham
 
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Joined: March 18th, 2022, 3:01 pm


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