PCB Repair Atari/Williams/etc.

crayzkirk

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I've worked on mainly Williams Defender/Stargate, etc. era PCBs and found them to be fairly sturdy with large pads and traces. I've been working on a couple of Tempest PCBs and they seem to be fairly flimsy with small traces and pads. What I learned (the hard way) on the Williams boards is that even with decent equipment (XyTronics 968 desoldering station, Hakko 936), a variety of temperatures and lots of patience, that attempting to remove an IC intact is asking for lifted pads (especially on the side with no trace attached). I will use a Dremel with a cutting wheel to cut the body off of the IC and then heat the leads and remove each with tweezers. Afterwards, comes the dangerous task of removing the solder left in the hole which usually means bye bye unsecured pad. It typically means flipping the board over to remove the solder from the side with a trace connected to the pad hoping the solder is fully removed and the unsecured pad remains attached.

So, my general question is how do you repair these boards without destroying them? I've done some practice on a couple of Atari boards and despite my best efforts, the pads seem to fly off the boards. What sort of tip size, temperature, etc. yields the best results? Or is some of this simply the result of working on old materials with the adhesive used to hold the traces/pads on the PCB material simply deteriorating? Add a little heat and instant destruction? How about one of those expensive PCB repair kits? I've even seen them for thru-hole repair.

Thanks for any and all suggestions!

Kirk S.
 
answer is more practice.

I thought the same thing initially when I started messing with Atari boards. It seemed to take me forever to remove a chip, and I'd often mess up the pad or trace. I initially thought it was the board, or the age or just impossible.. but it was just me.

Now I have it down to an art form. That said I don't use a desolder station, I bought one and found it useless. I just use my soldering iron and one of those "pump" and push button suckers like they sell at radio shack, where you press on a spring loaded pump then press release.

so my suggestion to you is simply practice more. make sure your iron is not too hot.
watch till you see the solder melt then give it an extra 2-3 seconds and then suck the solder out. good luck!

-brian
 
answer is more practice.

This. And patience. I haven't worked on any Williams boards, but have found classic Atari PCBs to be robust and forgiving. I have worked on them with a hand pump and 25w iron as well as a Hakko 808. Now that I have the 808 I would never work on a PCB with a hand pump unless I had no other option. If you had worse results with a continuous-vacuum desoldering tool, it was either defective or you were using it incorrectly. While a hand pump may be preferable for reasons of cost and simplicity, I can't think of a single instance where a hand pump is more effective than an 808. And one of the biggest advantages when repairing PCBs is that you can remove an IC without destroying it, which can be very useful for testing. You don't always know if the IC you suspect is actually the problem, so being able to reuse them can be a big help.

When using a hand pump to replace an IC, I use the same technique as you: clip the legs, heat from one side while pulling the leg out of the hole on the other, and heat/pump to clean. It works okay.

With an 808, put a blob of solder on the tip, apply it to the joint and wait 2-3 seconds for the solder to melt. Then hit the button and use the nozzle to rotate the IC leg through 360° — this prevents sweat joints from forming. If you do this to all the legs of your component, it should drop right out. Just yesterday I removed a 24-pin socket from a Battlezone PCB; it fell straight out after I had vacuumed out all the solder.

If you're using an 808 — any soldering tool, really — you must optimize for heat transfer, and the key to this is surface area. If you just press a hot tip against a joint, very little will happen because the area of the contact is too small for much heat transfer. If you put a blob of solder on the tip, the hot solder will deform to fit the joint, which increases your surface area, which makes the solder melt.

I did a bit of work on my Galaga PCB recently (just replacing caps) and it was terrible. Fragile pads and traces run so close together it's impossible to see if you've bridged without a magnifying glass and lots of light. It makes the Atari boards look like tanks in comparison.
 
Not to take it off topic but has anyone used a circuit specialist brand solder station? I've heard good things about the hako. But mine is a circuit specialist and I have not been impressed, that said maybe I have used mine incorrectly? I gave up pretty quickly then moved back to my hand pump which has served me except I cannot reuse old chips as at least one leg gets caught and I end up cutting it off. But does anyone have opinions about the circuit specialist desolderer to tell if its just me or if its the solder station?

Maybe I need to go back and practice more with it before giving up on it
 
Always add new solder to a joint you are trying to clear, it adds flux and more metal to conduct the heat. Means you can get it cleared faster and in one hit, rather than multiple roastings that causes the pads to lift.
 
Always add new solder to a joint you are trying to clear, it adds flux and more metal to conduct the heat. Means you can get it cleared faster and in one hit, rather than multiple roastings that causes the pads to lift.

+1

I also use the Hakko Iron w/ cheap desoldering bulb iron (radioshack).
 
Not to take it off topic but has anyone used a circuit specialist brand solder station? I've heard good things about the hako. But mine is a circuit specialist and I have not been impressed, that said maybe I have used mine incorrectly? I gave up pretty quickly then moved back to my hand pump which has served me except I cannot reuse old chips as at least one leg gets caught and I end up cutting it off. But does anyone have opinions about the circuit specialist desolderer to tell if its just me or if its the solder station?

Maybe I need to go back and practice more with it before giving up on it

I haven't used that kind. I tried a generic one — it would not come up to temperature brand new out of the box. I got a slightly older Hakko 936 for $50 off Craigslist. It's fantastic.
 
Thanks for the replies...

I also think part of the issue is that the boards are not virgin when I get them and I am typically reworking a prior repair. I always make sure to tin the tip with fresh solder for each pin, which is quite a PIA (no, not Peripheral Interface Adapter).

As far as socket replacement, do you use the double swipe sockets or roll your own machine pin strips? I like the single machine strips because I can always solder from the top to make sure any of those which may have lost the thru hole plating or the bottom pad is gone.

The unmasked area on the Atari Vector boards always seems to get in the way...

Kirk S.
 
Not to take it off topic but has anyone used a circuit specialist brand solder station? I've heard good things about the hako. But mine is a circuit specialist and I have not been impressed, that said maybe I have used mine incorrectly? I gave up pretty quickly then moved back to my hand pump which has served me except I cannot reuse old chips as at least one leg gets caught and I end up cutting it off. But does anyone have opinions about the circuit specialist desolderer to tell if its just me or if its the solder station?

Maybe I need to go back and practice more with it before giving up on it


If you are refering to the Blackjack 4000(?, sorry don't remember the number). There are two keys to it. One is to adjust the temperature correctly. I used a thermocouple to verify the temperature. And 2 is to use the smallest nozzle you can. They ship it default with the biggest one. It should just barely fit over the pins.

Once the solder melts, pull the trigger and move the nozzle in a tight circle around the pin. When you remove the nozzle, you should see a space around the pin. If you are not sure, flip the board over and look closely at the top of the pin. If there is no a hole at the base of the leg, you didn't get it all. You may have to slide the nozzle against the leg in order to use the leg to transfer heat to the top part of the solder joint. Especially on legs that attach to ground or power. These are typically much wider and the copper acts like a heat sink.

And of course practice, especially on boards you don't care about.

ken
 
Thanks for the replies...

I also think part of the issue is that the boards are not virgin when I get them and I am typically reworking a prior repair. I always make sure to tin the tip with fresh solder for each pin, which is quite a PIA (no, not Peripheral Interface Adapter).

As far as socket replacement, do you use the double swipe sockets or roll your own machine pin strips? I like the single machine strips because I can always solder from the top to make sure any of those which may have lost the thru hole plating or the bottom pad is gone.

The unmasked area on the Atari Vector boards always seems to get in the way...

Kirk S.

I prefer machine sockets, as they are much more reliable. I've had dual-wipes where the inner connector pulled up and tore off when I pulled a chip. This doesn't happen with machined sockets. I don't find them significantly easier to solder to the top of.

If you want boards to practice on, pick up some TVs for tube swaps and go to town on their chassis.
 
Not to take it off topic but has anyone used a circuit specialist brand solder station? I've heard good things about the hako. But mine is a circuit specialist and I have not been impressed, that said maybe I have used mine incorrectly? I gave up pretty quickly then moved back to my hand pump which has served me except I cannot reuse old chips as at least one leg gets caught and I end up cutting it off. But does anyone have opinions about the circuit specialist desolderer to tell if its just me or if its the solder station?

Maybe I need to go back and practice more with it before giving up on it
I have a BK6000, thats the single channel soldering or desoldering, with hot ait gun. It works well provided you get the temp right and are patient. I do agree about using the smallest tip possible on the desoldering gun. The bigger ones take forever to heat up. Cleaning it is another story. Ive had solder build up in the tube on the tip a few times. Not fun. Also the latch on the desoldering gun to hold in the solder tube broke in the first week I had it. Go figure.

Overall a cheaply made product that can work well if you pay attention to what your doing.
 
Patience is good advice, as many have said. Desoldering and rework is *hard*, contrary to what many people believe. Below is my list of suggestions/tools to add to what others have already said.

Also, the information at zeph.com changed a lot for me and made the difference between frustration and destroying parts to pretty much 100% success on everything I rework. If you can afford their products, great, but the technical information that is free on the site is invaluable.

Main tools:

* Chip-Quik. Digikey has a $20 kit with enough material to desolder quite a few ICs.

* Quality temp. controlled soldering iron.

* Nice to have: Vacuum powered desoldering station, if you can afford it.

* Hot air rework station.

* Hot air bath. If you can't afford a dedicated unit, you can make a setup with a decent heat gun and joist hangers available at most big-box hardware stores. Use a thermal-couple or oven thermometer to set the bath temp, and error on the low temperature side.

* 99% alcohol. No, the stuff you buy at the grocery store (isopropyl/rubbing alcohol) is not good enough.

* Q-tips, lots of them.

* Good solder wick, ideally with flux.

* Liquid or gel no-clean flux.


Chip-Quik is probably the best tool I have discovered for successful desoldering. It mixes with solder and changes the melting point to a much lower temperature, i.e. the hot-air bath temp., so you can make each pin molten and keep them molten at low temp to remove the whole chip at once and intact. It was mainly designed for helping to remove big SMD packages, but it works on any soldered part. For me using Chip-Quik is not optional, I always use it.

If you don't care about the part, one of the easiest ways to remove an IC without damaging the board is to cut the legs off and deal with each one individually. Otherwise, this is the process I typically use. This assumes you are working on the bottom of the board:

* Clean the board and parts to be reworked, top and bottom. Clean is the key to good soldering and easier rework.

* Use wick to remove some of the initial solder. Don't go crazy trying to clear the holes, just get the top layer of old solder off.

* Clean.

* Re-solder the pins with new solder! This helps mix with the remaining old solder and I have found that doing this makes the solder flow better, which means removing the solder is easier.

* Clean.

* Wick again. I usually find that I get a lot more solder out of the holes at this point.

* Clean.

* Set up the hot-air bath. Besides keeping Chip-Quik joints molten at the low temp, the hot-air bath also heats up the big power and ground planes and will let you desolder (and solder) the pins connected to those planes.

* Apply Chip-Quik to each joint. Once things are molten I usually wiggle the pin a little with the tip of the iron to make sure the Chip-Quik mixes with the solder all the way through the hole.

You may need to use wick to remove the first round of Chip-Quik if there is a lot of solder in the holes. So, wick, clean, reapply Chip-Quik if necessary.

* At this point all solder in the holes will be molten, so *gently* pry the part out of the hole. This can be a little tricky since you need to pry from the top, and the board is sitting upside-down over the hot-air bath. Alternatively you can push on the pins a little to start moving the IC. You can also take the board off the hot-air bath and turn it over for this step. The Chip-Quik will stay molten for quite a while.

* Wick the holes and clean them up with Q-tips and alcohol.

Alternatively if you don't have a hot-air bath, once you apply Chip-Quik to each pin you can use a hot-air rework station to heat the IC to the hot-air bath temperature (about 150C) and gently work the part out.

There are a lot of videos on YouTube about rework too, so watch many and take the best parts from each.

Hope this helps.
 
thanks for the advise, adding some solder and doing the "circle method" worked really well. now my desoldering station actually is useful, and yeah.. that was so much easier. One of these days I'm also going to look into a bottle of that Chip Quik stuff too.

-brian

If you are refering to the Blackjack 4000(?, sorry don't remember the number). There are two keys to it. One is to adjust the temperature correctly. I used a thermocouple to verify the temperature. And 2 is to use the smallest nozzle you can. They ship it default with the biggest one. It should just barely fit over the pins.

Once the solder melts, pull the trigger and move the nozzle in a tight circle around the pin. When you remove the nozzle, you should see a space around the pin. If you are not sure, flip the board over and look closely at the top of the pin. If there is no a hole at the base of the leg, you didn't get it all. You may have to slide the nozzle against the leg in order to use the leg to transfer heat to the top part of the solder joint. Especially on legs that attach to ground or power. These are typically much wider and the copper acts like a heat sink.

And of course practice, especially on boards you don't care about.

ken
 
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