Hi guys,

I just got done practicing soldering and desoldering on a spare ECU board and my old CRX ECU. Can you guys tell me how well I did? I thought I'd post this in FI instead of Tech or Audio/Sec because you guys have probably seen more turbo cars running chipped ECU's then those other guys have.

Here are pics of the desoldering. I had my iron set to 40W and I used up about a foot of desoldering braid to do the footprints for 74HC373 and the 256 chip. That black stuff you see in the pic is actually clear. I dont know if the braid is supposed to leave behind that clear residue, but it's all around the desoldered footprints.

DESOLDERING
http://www.imagestation.com/pi...2.jpg

And here is the practice soldering I did on a spare ECU boad and some 40 pin sockets that I bought from radio shack. The first link is my first attempt which I did about 12 hours ago. I tried to pull off the DIP socket and it wouldn't budge. I managed to keep the solder into uniformed blobs and the pins weren't contacting each other. On my first try there is a pin on the bottom left that has a little spillage. On the second try I got a little more spillage from one of the other pins. But I'm sure that can easily be cleaned up.

One other thing I noticed when I finished soldering is around each soldered pin on the ECU there is a very small amount of clear residue, the same type of stuff you can see in the desoldering pics. There's

ECU SOLDERING FIRST TRY
http://www.imagestation.com/pi...e.jpg

ECU SOLDERING SECOND TRY
http://www.imagestation.com/pi...f.jpg

 

It isn't the worst I have ever seen for a first time.

You look like you left it on there a little long. Using a foot of braid is a little much. You will get better with that the more you use it.

remember that some components are heat sensitive, go easy on the pressure and amount of time you use on each area.

That residue is from melting the PCB film.

I use mine at 35w, always seems to go good for me. I reccomend a small tip, not sure what you were using.

Good luck though, you will only get better with practice.

 

Thanks for the input. I tried several different ways of getting the solder out. My iron has a setting for 20W and 40W and I went with the 40W setting I tried it by setting the angled side of the tip on top of the braid which was on top of the hole being desoldered. I also took the tip and stabbed it straight down into the hole. But I dont think that worked any better.

Should I be applying pressure on the tip to get the braid onto the solder? or do I just hold the tip close enough so it melts the solder then once it starts to melt get the braid to pick it up? I was probably applying too much pressure to the tip. The tip I'm using was the smallest one they had there, the tip body looks to be about 1/8" in diameter.

 

You don't need to push down on the tip. I just lay the braid over what I am desoldering, and then heat the braid with the tip. The solder will wik up into the braid.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Cray91 &raquo;</TD></TR><TR><TD CLASS="quote">You don't need to push down on the tip. I just lay the braid over what I am desoldering, and then heat the braid with the tip. The solder will wik up into the braid.</TD></TR></TABLE>

Cool, I just did some more practicing desoldering and just like you said once the solder is heated up the braid pulls or wiks it up. I'm still getting a little bit of clear residue around the desoldered holes, but nowhere near as bad as when I practiced on the footprints above.

If there is still just a little bit of the clear film melted the ECU board is still ok right? I dont see how you can desolder with a braid and not make a tiny bit of mess.

 

FYI, I've had great luck with the $5 Radio Shack desolding iron. Never used the braid though, so can't compare.

 

The clear residue is just left over flux. Make sure you clean that up with isopropyl alcohol before you re-solder it. Clean afterward as well.

There are cheap desoldering 'plungers' you can buy. They're like a spring loaded syringe, just heat up the joint with your iron, place it over the pin and release the plunger. Solder goes right up.

Your 'second try' soldering job looks much better but remember that soldering on a pcb with lands on the bottom of the board your joints should NOT look like that. Yours have a slight bubble from the solder not getting pulled through the board. It's because there's no metal there to adhere to. When there is the solder should get pulled through the joint, it'll sit flatter at the bottom and not look as bulbous. It should come to a point, looking like the bottom half of this )( rather then the top half of this () sorry for the ASCII but I don't have pics of good joints laying around.

 

I use a Hakko 926 ESD temperature controlled station with a 900 iron. What would the equivalent temperature [in deg F] be to say 35W?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Paul_VR6 &raquo;</TD></TR><TR><TD CLASS="quote">Yours have a slight bubble from the solder not getting pulled through the board. It's because there's no metal there to adhere to. When there is the solder should get pulled through the joint, it'll sit flatter at the bottom and not look as bulbous. It should come to a point, looking like the bottom half of this )( rather then the top half of this () sorry for the ASCII but I don't have pics of good joints laying around. </TD></TR></TABLE>

I think I understand what you are saying. I'm looking at the back of my CRX ECU and the soldered pins that were already there dont look like bulbs like on my practice board. Instead the base of the solder is sloped inwards like in that example you used: bottom part of: )(

So you're saying that when I solder on my actual ECU board, the base of the solder wont be bulbous, but instead sloped inwards like the bottom part of this: )( And that's because the actual ECU has metal around the pinholes, whereas my practice boards does not.

I think I'll run back to Radio Shack and grab a syringe too. I have this little ball shaped pump, but it isn't strong enough to pick up the solder, so I need something better.

Thanks so far for the replies everybody

 

Yep, the joints should look concave [the word everyone was searching for].

 

The solder should look relativly flat across. Just enough to completley fill the joint up. It shouldn't bubble, if it does you can heat it again and see if it flows through the joint, or you can lay some briad on it and suck up the excess. You don't really need to flow the solder the whole way, but I would recommend it for a good looking solder that will last. What size diameter solder are you using. Try to use just about the smallest they sell at radio shack, you can get it right in the joint, and it flows very well.

 

I'm using 0.32 diameter solder, and I think the smallest one I saw at the store was .022 diameter. I might pick up some of the as well, maybe it will be small enough fr me to actually stick into the pinhole along with the pin. That way I can melt the solder while it's in the hole making it easier to fill.

One other question I had though, is it really necessary to heat up the pin before I melt the solder around it to make a better connection? I hear people say that it's a good idea to heat up wiring when you solder them together, but is it the same way for the teeny tiny pins?

TIA

 

Just heat the joint, you can heat the pin or the pad, just so that you can get the solder to "flow" into the joint, you don't even have to make it hit the soldering iron. I use .32 diameter as well, the silver bearing solder, works very nice after you get the hang of it. It just takes practice. We can sit here and tell you how to do it, but like you are doing right now, it takes practice. I like to see people doing it on their own.

 

I always try to heat the joint and push the solder into that instead of into the iron.

 

need to be carefull when desoldering cause if you leave the gun on the board to long you can pull the pad right off with the solder.That sucks cause i did that my first time, i had to solder the pad back on and still have contact with the rest of the board and also still have a hole to put the legs in.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by DaX &raquo;</TD></TR><TR><TD CLASS="quote">Yep, the joints should look concave [the word everyone was searching for]. </TD></TR></TABLE>

That was the word I couldn't find earlier.

Don't forget to clean and tin your iron often as well.

 

hey again guys,

I practiced soldering a 40 pin socket chopped down to 28 pins on my CRX ECU. My soldering job for the modified 28 pin socket onto my CRX ECU went pretty well. There are a few holes that I didn't fill completly but that's cause my work area isn't very well lit.

I found a spring loaded syringe, but is still doesn't do a good enough job at clearing solder out of ECU holes. So I guess I'll just stick to using desoldering braid.

I just had one other question about soldering wires into the ECU pin holes. I'm gonna wire in a datalogging cable to CN2 and a switch for J1 instead of using a wire jumper. What gauge wire will fit into these ECU pin holes?

TIA

 

I think I used 18 gag. You could also just cut down on a bigger gauge if you couldn't find anything smaller. I use desoldering braid all the time. It gets expensive but I like it better than the iron. THe iron just makes me mad.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 93turbo16 &raquo;</TD></TR><TR><TD CLASS="quote">I think I used 18 gag. You could also just cut down on a bigger gauge if you couldn't find anything smaller. I use desoldering braid all the time. It gets expensive but I like it better than the iron. THe iron just makes me mad.</TD></TR></TABLE>

I just wanted to ge the correct gauge wire. I might have some 18ga wire laying arund but I'd have to check. About the braid, I dont mind using it...I dont think I'll be soldering too many ECU boards. Maybe just for a few of the locals that want me to chip their ECU's, but I dont know if I'll be offering my services to all of H-T anytime soon. hehehe

 

Good to see people doing things like this. When I first started I practiced on an old printer board that was busted and the internals of a Television

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by xenocron &raquo;</TD></TR><TR><TD CLASS="quote">Good to see people doing things like this. When I first started I practiced on an old printer board that was busted and the internals of a Television </TD></TR></TABLE>

well my TV and printer haven't broken down yet so I dont think I can use them for practice. hehehe

My practice run with my CRX ECU and socket install looked pretty good. The solder filled out the hole, and the base of my solder points were flat and a little concave instead of round and fat like on my practice board. The only thing I'm really worried about now is all the melted clear film when I desoldered my CRX ECU.

Even if that clearcoat stuff is a little melted and all wavy looking, the ECU will still work fine right? it's not like any of the pathways (or whatever you call them) got damaged when I desoldered.

I'm still very wary of desoldering the 74HC and 256 footprints on my P72. I have my chipped P28, which only needs two ceramic capacitors. The P28 is what I've been using anyways for testing out my burned chips. I was gonna sell the P28 after the P72 was chipped, but now I'm thinking I may hold onto the P28 and leave the P72 stock. If I screw up my chipped P28, I will just get another virgin P28 and chip that instead of my P72.

 

Dont be skurred man...just do it. Be patient and take your time is all...the only time you really screw up an ECU is when you are rushing.