I think everybody will tell you this, find a old electronics pcb with something in similar size throughole soldered on. Doesn't have to be as many pins like the cpu but similar solder joint size and spacing then practice on that.

Im sure you already found some material on basic desolder techniques.

add flux, new solder to mix with the old one for better melting and technique with desolder gun

Keep practicing until you can cleanly remove worthless components from worthless boards while spending maybye 1 - 2 seconds per joint not to overheat and damage the chip

uscleo wrote:

I have access to a professional de-soldering station with electric suction pump and copper wire braid, etc., I just don’t have all that much experience and I don’t want to ruin my board.

That's perfect. Like suggested, just practice on some old electronics stuff that is already broken beyond repair. Once you get the hang of it, only then go and desolder the cpu from that board.

https://www.amazon.com/gp/product/B07542D82F/ … 0?ie=UTF8&psc=1

worked fine when I replaced a pair of pentium pro sockets. (387 pins x2)

I'd imagine a 486 would be much easier.

word(s) of advice, GO SLOW. It is weapons grade chineseium. You need to adjust to the tool, not the other way around.

For video content on soldering, watch these: https://www.youtube.com/results?search_query= … vblog+soldering
also, my signature below has the IPC guides on 100% proper techniques.

Ive never seen a PGA cpu soldered directly to board without socket.. that sounds crazy to me.

uscleo wrote:

I have a project where I’m trying to de-solder a 486 CPU from a PCB – its directly soldered in, through-hole, to the PCB, then solder in a 486 socket. I was wondering if anyone had any tips on how to go about this

solder pot/bath is the easiest/quickest method, but I suspect you wont have access to one
upside down in the station letting gravity do the work is the second best option
It would be advisable to pre heat the board, aka bake it around 100 Celsius for a while to remove moisture

desoldering guns are a tedious slow way preferred by old school people used to thru hole

wiretap wrote:

For video content on soldering, watch these: https://www.youtube.com/results?search_query= … vblog+soldering
also, my signature below has the IPC guides on 100% proper techniques.

exactly like Dave from EEVBlog, be advised Dave doesnt practice soldering daily, last time he tried to do hotair rework he ended up buying new motherboard

uscleo wrote:

or if anyone could recommend someone that’s really really good with fine job soldering / de-soldering?

continent? planet?

uscleo wrote:

I have access to a professional de-soldering station with electric suction pump and copper wire braid, etc., I just don’t have all that much experience and I don’t want to ruin my board.

forget copper braid, this is how you lift pads, best solution would be asking the person usually working that de-soldering station

BloodyCactus wrote:

Ive never seen a PGA cpu soldered directly to board without socket.. that sounds crazy to me.

FM Towns just to name one https://gdemu.wordpress.com/2018/08/24/catch-me-if-you-can/

Deksor removed a 486 cpu socket in this thread using a desolder gun, My new 486-386 junk boards [IT gore] (last post on page1)

so its definitely doable but its not a quick job and highly recommend you practice your technique first, one time I broke a really nice board trying to desolder a rtc without knowing how (lucky I fixed it months later)

yeah forget copper braid for desoldering through hole

I would use a heatgun for such a thing. It'll only take 5ish minutes to get the CPU off board without disturbing anything else if proper precautions are taken. Pin by pin methods take a lot of time and there's good chance of ruining vias during final extraction.

Braid is useful only for removing shorts between pins, getting rid of excess solder and cleaning pads of a surface mounted chip prior putting one back.

Tiido wrote:

I would use a heatgun for such a thing. It'll only take 5ish minutes to get the CPU off board without disturbing anything else if proper precautions are taken. Pin by pin methods take a lot of time and there's good chance of ruining vias during final extraction.

Braid is useful only for removing shorts between pins, getting rid of excess solder and cleaning pads of a surface mounted chip prior putting one back.

DO NOT EVER FUCKING DO THIS. THIS IS BAD, HORRIBLE ADVICE.

I've had 100% success rate without any sort of complications, for larger boards you'll need to do preheating or warping can cause problems. Know your tool and use proper techniques and there's no chance of failure.

well, if it was an SMD processor, it makes sense, but not one with pins.

Yeah, I wouldn't call it a sound advice either. I mean, sure, it's possible - but there's a ton of assumptions made here. One needs a quality heatgun with good temperature control, and even then a steady hand and considerable prior experience is required to know what temperature to set, how far the nozzle has to be from the PCB, how long it should take to see the effects, etc. Definitelly not something I'd recommend, or even try myself and I've desoldered a few PGA chips.

I fully agree with "Know your tool and use proper techniques" - it's just that there's a lot of hands-on experience hidden behind that sentence. That's like saying open heart surgery is simple, you just need a sharp scalpel.

The procedure is something a beginner will most likely fail at, regardless of method but I stand by what I said earlier, there's very little chance of failure with a proper tool. Person who will be capable will likely already know the techniques and has knowledge of their tools etc.

I will add 1 thing here, especially on old boards even when all the solder is sucked out or melted by a heatgun alot of the through hole components do not simply fall off with gravity, there is 20 years worth of suction dust dirt whatever. Everytime I desolder a chip using a gun even when all the joins look 100% clean it is still some wrestling with the chip to loosen it. Makes it very very hard using a heatgun with 1 hand while trying to pry the chip off, however yes there is always the stress in your mind about the vias coming out when trying to "rip" out a chip with all the solder joints clear. I usually play with the pins from under the board once solder is sucked to see they are really free and not stuck.

The procedure could be done both ways sure, I never used a heat gun to remove through hole chips, was forced to do it for a smd chip because there was no other way but I had no success ever lining it up perfect and resoldering using a heat gun (iPhone 5 power ic chip)

Right nozzle also plays a big role, for all sort of connectors I use one that creates a line of air and even things like RAM sockets come out without much effort. Special attention is needed for connectors with soldered locking pins, those must be freed first. DIP chips, especially large ones like 68000 are also very easy with such a nozzle.
The heatguns attached to many soldering stations are not useful, they have too little air flow and thus the heat is fairly localized and you got to move the hand a lot while trying to get evenish heat distribution. Chance of scorching a board goes high, due to that these small heatguns are useful only for small parts. A large multi hundred watt heatgun will allow you to do things without any manual effort, just hold it in place at say 5cm and things will happen easily on their own. High airflow will also help to prevent flexing and bowing of the board. I use heatgun to remove parts, putting them back is job of regular iron. Stuff with powerpad underneath can be done with regular iron and dab of solder paste if other side of the board allows heating with the iron.

Honestly use a hot air gun, it's what i use to remove IC's quickly without much fuss, just be careful

Tiido wrote:

Braid is useful only for removing shorts between pins, getting rid of excess solder and cleaning pads of a surface mounted chip prior putting one back.

thats exactly how you rip pads off
https://www.youtube.com/watch?v=0nWrx8QcNiI

granted it might work better for thru hole with quality plated vias, but in general I would avoid dragging abrasive bundle of copper over cheap chinesium pcb full of delicate tracks/pads

That's why you don't drag, but place, heat, lift, move to new location, repeat... And if you absolutely want to drag add some flux, it acts sort of as a lubricant and lets the wick skate on it.

Liberal amounts of flux is key. Using enough flux, the solder will flow off the pad into the braid.