Desoldering 30-pin Simm sockets

[nvdeynde]

I've got a few SE and SE/30 boards with broken clips on the Simm sockets.
What would be the best option to remove these from the logic board without lifting traces or damaging the PCB ?

I have a desoldering station but I don't think this will work as the Simm sockets come in pairs so there are 60 pins that have to be free...
An option is to cut the dual Simm socket in the middle so there are only 30 pins left to desolder.

I've tried it on a scrap board but didn't succeed in desoldering all 30 pins. The solder is really on both sides of the PCB.

[Mark2000]

Sounds like you just need to get a solder wick and clean all the solder off the board on one side and then the other. The pins wil just fall out themselves. You should be doing this no matter what. Old solder is, well, old. You won't want any of it left if you can help it.

[mcdermd]

What Mark2000 said. You'll probably want to suck/wick it out.

[techknight]

or do what I do, break the SIMM socket off the board and pluck each pin out 1 by 1.

if you need to pull and save the socket, things get alot tougher. This is a 4 layer board so unsoldering is a royal B***H. Pull as much as the solder you can, and heatgun it. the board will get really soft and will end up melting all the solder so you can pluck it. you may burn/scorch the board this way (very likely) but if its a parts board it dont matter anyway...

[dougg3]

If you plan on doing a lot of desoldering without destroying the removed part, this might be a worthwhile investment, although it's pretty expensive (maybe a bit cheaper on eBay?):

http://www.amazon.com/Hakko-Desoldering ... B000ARPULW

I haven't tried it with a SIMM socket yet, but it works wonders for 32 pin DIP chips...I personally never succeeded at getting all of the solder out with wick, especially on power and ground pins. There was always a little bit of solder left still holding each pin in. But with this thing it was almost too easy. Just thought I'd throw that out there...

Otherwise, I'd say destroy the socket like techknight said.

[nvdeynde]

I check the Hakko desoldering station. The temptature range in the specs is very high 380-480°C/715-895°F.
I have a desoldering station from Pace and hardly ever desolder higher than 320°C, where the minimum of the Hakko is 380°C.

Won't this burn the PCB or do you want a very high temperature to get out all the old solder ?
Sure I can set mine at 480°C too, not good for the lifespan of the heather, but it's possible.

My experience with the scap board: I wasn't able to free all 30 pins...

I do want to learn it properly before I start working on good boards.

[dougg3]

Oh, I didn't realize you already had a desoldering station! Sorry, I just now noticed you said that in your original post.

True, it is pretty hot. I haven't had any problems scorching boards yet though...I think as long as you act fast it works OK. My experience is you stick the nozzle over the pin and wiggle it around until you can feel the pin moving (meaning the solder is completely melted) -- this should only take about a half second to a second, if I'm remembering right. At that point, I try to move the pin so it's not touching the edge of the hole in any spot. Then I pull the trigger, pull the nozzle off the pin with the trigger still down, let go of the trigger, and everything is completely gone. I don't know if it needs to be that hot or not, but like you said, I can't go any lower than 380° C with mine. What I can say is I pulled all four ROM chips off a IIci motherboard using that technique with no damage to the motherboard or the chips...

Maybe adding some fresh solder to each pin (or stubborn pins) before sucking it away would help? I seem to recall I had to do that on a few of the ROM chip pins.

[8bitbubsy]

The Hakko desoldering gun you linked is a master's item, it doesn't just work, it works brilliantly!
I recommend it, even though the price is a bit stiff.

[nvdeynde]

Even though I have a desoldering station from Pace, I'm considering the Hakko 808. There's just one problem: I can't find it for sale anywhere in Europe.
Did they even make a European 230 volts version ?

Anyway importing a 110 volts version from the USA in not an option for me as I will be paying double for it due to very high import duties here + the need for an additional step down transformer.

I'm disappointed Amazon UK doesn't sell it.

[dougg3]

I'm pretty sure they make a 230V version. Hakko's distributor page may be useful. I see a Hakko 808 on one of the UK distributor sites, and their price list mentions a 230 volt heating element.

I agree, it's a nice piece of equipment. I'm very careful about cleaning it after using it, and making sure the filter is installed correctly and clean, and I haven't had any problems. I have had it start shutting itself off due to getting too hot, but that's alleviated by slowing down a bit and not holding down the trigger too long

[8bitbubsy]

I'm using the 110v American version with a 100W 220v->110v step down converter. The gun takes exactly 95-100w IIRC, I was pretty lucky to have a 100W step down unit already.

[nvdeynde]

I see a Hakko 808 on one of the UK distributor sites, and their price list mentions a 230 volt heating element.

Indeed they have the desoldering gun but the price is excluding 21% of VAT so extremely expensive compared to USA prices.

Anyway I have a Pace rework station with a desoldering piece and hot air Thermojet so this has to work.
My first attempts that didn't succeed were with my desoldering iron only. Now I used the whole set

After a few trials and error, I ended up doing it like this:

- I first used my hot air Thermojet with a very fine nozzle set at 340°C and melted the old solder
- This didn't free the pins of course so I re-applied fresh solder to all 30-pins with an iron at 320°C and wiggled against the pins until they were loose in the fresh solder
- Then I set my vacuum pump at maximum power, desoldering iron at 340°C and used one of my larger desolder tips ( a Thermodrive ) to remove the remains of the old solder and the newly applied solder and it worked out.

I could then easily remove the complete 30-pin socket. I tried this technique on a Mac Plus logic board and it works like a charm.
I did cut the Dual 30-pin socket between the 2 rows first as 60-pins at once was an unncessary risk.

I guess the combination of the Thermojet and a larger Thermodrive tip for desoldering was the key to the solution.
Absolutely no damage to the PCB since I could keep the temperature pretty low.

[dougg3]

Glad to hear that worked! Sounds like your desoldering station works just fine

[nvdeynde]

Can anyone find replacement 30-pin sockets for an SE/30 or Mac IIsi for example ?
These are straight with a spacing of 10mm between 2 rows.

I have been looking for hours and wasn't able to find them anywhere.
Dontronics and Jameco sell sockets but the spacing is wrong so they don't fit on the PCB.

http://www.dontronics-shop.com/sim-sockx2.html

and

http://www.jameco.com/webapp/wcs/stores/servlet/Product_10001_10001_1954746_-1

It are just my SE/30 logic boards that have the most broken plastic clips

[trag]

We were just discussing this in a thread on Trading Post. A great deal of searching has not turned up the sockets with the proper spacing for the SE/30. It looks like the Jameco sockets could probably be sawn apart and used.

If you'd like to try it shoot me a PM. If it works for you, maybe I'll offer them for sale with the capacitors.

And since I'm posting anyway, I'll mention that I like to use an adjustable heat gun for desoldering, going back to the earlier discussion. I wasn't going to bother, but as I wrote, I'm already typing.

A desoldering station is almost certainly better, if you have or can afford one, but I've had great results with my Milwaukee heat gun. It has a dial on the back for continuously adjusting the temperature from room up to I don't know. It goes from 1 to 10, so that could be 100 to 1000F, but I don't know. I find that a setting of 8 to 9 for one or two minutes will nicely desolder things like 32 pin DIPs.

I use a lot of modeling clay -- the stuff that stays soft that you can get at Hobby Lobby. The stuff I have is gray/white uncolored. I've seen green, but I think the dye might be a bad idea.

The first thing I use the clay for is to cover nearby components that aren't involved in the desoldering operation. The first time I used a heat gun for desoldering, I blew a bunch of SM resistors and resistor arrays off the board and I had no idea where they came from.

Small parts are usually in rows and columns, so I just roll some snakes of the proper length and then press the snake onto the row or column of resistors or caps, to protect them.

The other thing I do with the clay is build little pedestals. If I'm desoldering a through-hole component, like a 32 pin DIP or a SIMM socket, I'll support the board on little clay pedestals with the component on the underside. As the board heats, I test the solder by poking the through holes with a dental pick. That way if the heating is uneven, I can detect which holes need a little more heat. It also helps to give the pins a little push once all the solder is melted, so get the component to fall out.

I must have desoldered at least forty 32 pin DIPs this way when I was converting UltraTek/66 cards. And I was able to reuse every Flash chip I desoldered. There was a resistor that needed moving, under the flash chip, plus it simplified reprogramming the flash once it was off the board.