so how do you guys desolder the original nes rom chips? I usually cut the rom off with wire cutters, then take out the pins that were left, and finally use a solder sucker to suck out the remaining solder...but this is getting really old and is very time consuming. is there an easier way?
RadioShack desoldering iron with built in sucker. It sucks.
I would love to drop $200 on a hot air-vacuum station, but, you know, the $200 part. I dream of IR.
I have like the most basic desoldering pump ever. It cost me $7, and It's a manual pump with a thing you push down, then press this one button, and it acts like a really quick vacuum. It works just fine, but when you press down the thing again, you have to press it over somewhere where a bunch of solder dust can fall. I have no trouble with it. Takes me about 20 minutes to safely remove a chip without breaking pins/tearing IO lines. You don't need anything too pricy, you just need it to have a good vacuum force for like half a second.
I've pulled off MANY pads/traces with those, they're quite violent.
With simple desoldering pumps? I can't imagine how one can pull traces off with those... They barelly touch the board...
That's what I use too, and most of the times I'm able to get the ROM out in one piece. I'm kinda tired of that though, and am considering starting to cut the legs and calmly remove the pins one by one, as describe above.
The regular pump way is a bit difficult in the end of the process, when some pins refuse to detach from the board, and you feel like you'll break the board with the force used to pull out the chip. Then you may even pull traces off.
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With simple desoldering pumps? I can't imagine how one can pull traces off with those... They barelly touch the board...
No, it's because you have to heat the solder up so much first that this weakens the adhesion of the nearby traces to the board. I need to try the heat gun/hair dryer approach mentioned in other threads.
I've been using the radio shack one and it works great. I've had to replace the tip on mine, but other than that I love it. I don't cut the pins. I just wait till the tip is good and hot, suck a row of pins, and then let the tip warm up very quickly before continuing. I'll usually suck each pin twice and I clear the tip by blowing on a piece of cardboard between suck. It's slightly tedious, but it only takes a few minutes.
Desoldering braid. Copper wire braided together. Put this down on what you want to lift, apply a fine tip soldering iron and the braid absorbs and traps the solder. Just remove the braid with the iron or the braid will be soldered to the board. If that happens just apply the iron and lift together, no biggy.
Works so much better then a sucker IMO. Just dont get the radioshack stuff. ITs useless, the braids are as loose as hookerbot 2000. The only downfall is its perishable. You have to keep buying it.
blargg wrote:
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With simple desoldering pumps? I can't imagine how one can pull traces off with those... They barelly touch the board...
No, it's because you have to heat the solder up so much first that this weakens the adhesion of the nearby traces to the board. I need to try the heat gun/hair dryer approach mentioned in other threads.
Don't bother with heat gun. It gives too much heat and will actually burn the PCB. It will also cause other IC's next to the ROMs to fall out. When the ROMs fall out, the through holes will still be sealed, and you still need to get the solder out.
The only thing that works is either a really good desolder station (radio shack crap is as good as a 20$ solder.. works well for 5 PCBs but not 50+) order the hard way (clip ROMs and then use pump).
Take it from a person who made over 100 boards.
can you recommend a good desolder station?
leonk wrote:
blargg wrote:
Quote:
With simple desoldering pumps? I can't imagine how one can pull traces off with those... They barelly touch the board...
No, it's because you have to heat the solder up so much first that this weakens the adhesion of the nearby traces to the board. I need to try the heat gun/hair dryer approach mentioned in other threads.
Don't bother with heat gun. It gives too much heat and will actually burn the PCB. It will also cause other IC's next to the ROMs to fall out. When the ROMs fall out, the through holes will still be sealed, and you still need to get the solder out.
The only thing that works is either a really good desolder station (radio shack crap is as good as a 20$ solder.. works well for 5 PCBs but not 50+) order the hard way (clip ROMs and then use pump).
Take it from a person who made over 100 boards.
leonk wrote:
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Don't bother with heat gun. It gives too much heat and will actually burn the PCB. It will also cause other IC's next to the ROMs to fall out.
I saw someone recommend a way to avoid this problem when using a heat gun. Take a piece of aluminum foil and cut out a hole just large enough for the part your removing (ROM) to fit. Place this over the board, apply heat. The foil will act as a heat shield, protecting the other parts. It's not a great shield, but it's enough to prevent damage.
I know the RadioShack desolder is cheap but I have had very good experience with it on the NES cartridges. The mask ROM's come off in perfect shape and the solder traces and holes are left in excellent shape with very little solder and ready for the EPROM sockets. You do have to make sure the tip is clean and tinned and have to apply the tip for a few seconds till the solder melts (it looks different-sort of liquidy) before sucking. I find it much better than the two suckers and braid that I also have.
Radio Shack Sucker is the only one I have ever used. It works great. Doesnt burn the PCB if you do it correctly, and it usually gets the solder out on the first suck. Not to mention its portable and works fast.
Forget the 200$ station, this thing works just as good for NES games.
Braid is useless for pin through. It's only good when you're trying to remove solder from a particular spot (be it solder in a hole or working with surface mounted IC's).
Lloyd Gordon wrote:
I know the RadioShack desolder is cheap but I have had very good experience with it on the NES cartridges. The mask ROM's come off in perfect shape and the solder traces and holes are left in excellent shape with very little solder and ready for the EPROM sockets. You do have to make sure the tip is clean and tinned and have to apply the tip for a few seconds till the solder melts (it looks different-sort of liquidy) before sucking. I find it much better than the two suckers and braid that I also have.
I agree about the braid and pins. I don't understand how it can be used easily to unsolder a chip. Until I start doing hundreds of these, it's Radio Shack sucker for me.
And yes, one suck usually does it, but I almost always do a quick two and then I hardly ever have to worry about a bitch pin. With the second suck, I usually let the pin get in the hole and wiggle the pin so i know it's loose.
I never could understand why some folks would cut legs and ruin the chips to get'em out, and now I know why. I was trying to take the SRAM out of my dead Dragon Warrior today, and found it's nothing as easy to remove chips as I thought.
Granted, all I have is a push-button solder sucker, desoldering braid, and a soldering iron, which is probably not the best of tools. But some of them came out rather well with the sucker. Though you always end up with just a small few asshole ones which you can never suck out entirely. I tried the braid on those repeatedly, but couldn't get it out. I even re-soldered and repeated the above process, and still no good.
Eventually I broke some of the pins by twisting'em from the bottom (the first couple by accident), and then was able to force the chip out. The board is still in relatively decent shape, but unless I can put pins back on the SRAM (it's missing about 4), the whole thing was probably only good as a learning experience.
I think I need to either get this Radio Shack desoldering iron, or try to find a set of snippers small enough to snip the legs. I'm not sure where I'd even find the latter.
I've resoldered pins onto EPROM chips and they've worked fine.
Yeah, but when the whole pin falls off, it's pretty much impossible. And also, if you solder the pin back on, when you solder the chip into a board, the solder on that pin will melt when you get to it. It happens to me sometimes, when I'm soldering stuff together. If you touch a copper wire with the soldering iron, and the wire has solder at the end, the solder will melt, because the copper wire is so hot. The same rule applies for soldering pins back on to chips. Sorry, if that made no sense.
Welp, I just managed to remove the PRG chip from that Dragon Warrior board totally unscathed, board as well. The secret? Heating from the top, sucking from the bottom. I know, that's probably a totally noobie suggestion, but that split second it takes to move the iron away and put the sucker in place when doing it all from the bottom is a lifetime in terms of solder staying molten. Sometimes doing it from just the one side will work okay, or could take a few attempts, and other times it just won't. I got every pin on the first try when heating from the top.
Well, I still had an "asshole pin", but I'm coming to find out that generally these are power and/or ground pins, which from what I've read elsewhere, are possibly like that on purpose, and need more heat. So I just held the iron on it till it got its typical level of mushy (since it doesn't seem to ever get thoroughly melted), then slid the chip out with a screwdriver. An IC puller would surely have worked better, but I don't have one.
The problem is that I probably would have never been able to do the heat-from-top method from the beginning, since the WRAM chip is so close to the other, and I have a lame soldering iron tip which is even-widthed, right down towards the very end, then suddenly goes to the fine tip. It'd have never fit between the chips to heat the joints on those legs. So I guess the biggest trick is just getting a soldering iron with a decent tip on it!
Power/Ground pins are harder because they have a large plane for the board traces instead of a tiny wire. That plane acts like a nice heat sink when you are trying to desolder. Those pins are generally on the upper right and lower left of the chip, when the notch is at the top.
For using the solder sucker I usually mount the board vertical in a clamp so I can have iron on one side and sucker on the other. If it doesnt suck out all the solder on the first try it can help to reapply some fresh solder and try again.
Good points, I forgot to mention that I used one of those cheap little dual-clamp things with the magnifier and such. I tried putting extra solder on the power pin though, but it just wouldn't budge. But the ground came out on the first try!
Now the problem is trying to squeeze two 32-pin sockets into two 28-pin sets of holes. X_X
Easy, just cut off the extra 4 pins
lol not if I need to use those four pins.
I guess it'd be okay to fold them outwards from the socket and solder wires on the tops, then put tape or something on the board to keep them from coming into contact with it. It'd be better to use either 28-pin eeproms (and sockets) or a board with 32-pin chips, but I don't have either, and I'd hate to let it go to waste, even if it ends up looking a little sloppy when I'm done. And if the MMC1 is dead (like I'm guessing it is), I figure I'll just direct-connect the address lines with jumper wires, and at least get an NROM board out of it.
By the way, with these chips unsoldered, would it be possible to read them in like a Willem programmer without any modification? I don't see any options for such a chip in the software of course, but I figure all those switches on the hardware might have a possible configuration to allow it. It just didn't come with instructions for what they all meant!