Heat gun advice

[msknight]

This is going to be an unnecessarily long one, just to get people to know where I'm going and what I need.

Firstly, I'm working on retro 8 bit machines and occasionally have to remove chips. Being on a budget I have a ZD-915 desoldering tool, but as you know it gets 95% there and leaves enough pins with a small amount of led solder on, to prevent the chip from lifting clean.

It obviously needs a small amount of directed heat to do enough melting to allow the chip to lift, but I'm having a heck of a job trying to find something. Obviously I've got larger heaters for removing mobile phone backs, but that's too large and delivers too much heat, to use on a 40 year old computer.

I've been watching a number of videos and saw Adrian's Digital Basement where he uses a Gaoyue 858, but there seems to be little information about it. Looking it up on Amazon, I see reviews equally split across from 1 to 5 stars with people getting white smoke and destroying their units. Some of this sounds like it's down to not knowing how to use it properly... but that's another problem... I can't find any reliable information that would give me confidence to know that I wouldn't make the same mistake.

So I'm asking here for advice and recommendations for a rework/heat unit that can finish the job of delivering enough focused heat over a chip to finish the job of lifting it, without over heating neighbouring components... and on a budget, as I'm a hobyist. Let's say £50 just to ball park it, but I can be flexible. If recommended unit have good numbers of videos/documents to demonstrate how to use it properly and safely, then that's a very welcome bonus.

[jchw4]

So I'm asking here for advice and recommendations for a rework/heat unit that can finish the job of delivering enough focused heat over a chip to finish the job of lifting it, without over heating neighbouring components... and on a budget, as I'm a hobyist. Let's say £50 just to ball park it, but I can be flexible. If recommended unit have good numbers of videos/documents to demonstrate how to use it properly and safely, then that's a very welcome bonus.

Do not buy the heaters with the fan in the handle.  Just stay away.
Very loud, heavy and does not produce enough air. Prone to overheating and difficult to fix when the handle melts. It will definitely melt at some point because the fan does not produce enough air.

I recently tried Quick 957DW+ and I can fully recommend it. https://www.tequipment.net/Quick/957DW+/Desoldering-Equipment/Rework-Stations/ sells it for $105 now with free shipment. Probaby US-only but not should not be very far from your budget even in UK.

It is much better than the old budget models:

1) All-metal case, pretty quiet, claims 580W.

2) Tool rest (magnetic) sensor in the handle! Will automatically cool down and stop when parked. I did not expect that for the price.

No fancy controls but does exactly what you would expect.  I did not disassemble the handle so I don't know what's inside.

It's still cheap so do not expect anything fancy but I was very pleasantly surprised.

This is going to be an unnecessarily long one, just to get people to know where I'm going and what I need.

Firstly, I'm working on retro 8 bit machines and occasionally have to remove chips. Being on a budget I have a ZD-915 desoldering tool, but as you know it gets 95% there and leaves enough pins with a small amount of led solder on, to prevent the chip from lifting clean.

It obviously needs a small amount of directed heat to do enough melting to allow the chip to lift, but I'm having a heck of a job trying to find something. Obviously I've got larger heaters for removing mobile phone backs, but that's too large and delivers too much heat, to use on a 40 year old computer.

I did not have a chance to try ZD-915, but I own Hakko and old Aoyue tools. I also had a chance to try a similar high-end Metcal tool once. I feel that they are all the same in terms of performance, the difference is only in maintenance and available options.

In my experience none of them leave any significant (i.e. visible) amount of solder if you do it right. You need to make sure that the solder fully melts on the other side of the board. I usually look at the other side and wait for the pin to move freely around the hole before pressing the suction button. As you probably already know,  there is usually a single chance to push the trigger.  If it did not work the first time you will have to add fresh solder and start over.

But usually it does not leave any solder residue. If it did then I made a mistake.

[msknight]

Thanks very much for the advice. I have found a seller for that unit in the UK and for something that is reliable, I'll certainly jump to that price.

[Solder_Junkie]

With regard to removing DIL type ICs, DO NOT USE HOT AIR... Hot air works well with SMD parts, but you risk board damage trying to heat through hole ICs. The safest way to minimise damage is to cut the legs close to the IC body, then heat each pad to remove the leg using narrow nose pliers or tweezers. Use a temperature controlled iron to reduce the risk of pad/track/board damage. Clear the holes with solder wick or a solder sucker, Using solder wick there is probably less risk of damage by overheating. Remember, it is cheaper to replace an IC than it is to replace the whole board.

SJ

[msknight]

Thanks SJ.

I appreciate what you're saying about the heat, etc. However, on the vintage systems some chips are not replaceable, either not made any more, or operate at the wrong speeds. It's proving to be quite the problem, especially having to harvest parts from dead systems to make one living unit.

[tooki]

Firstly, I'm working on retro 8 bit machines and occasionally have to remove chips. Being on a budget I have a ZD-915 desoldering tool, but as you know it gets 95% there and leaves enough pins with a small amount of led solder on, to prevent the chip from lifting clean.

It obviously needs a small amount of directed heat to do enough melting to allow the chip to lift, but I'm having a heck of a job trying to find something. Obviously I've got larger heaters for removing mobile phone backs, but that's too large and delivers too much heat, to use on a 40 year old computer.

Before you buy anything, make sure your desoldering technique is correct. Your statement of getting  “95% of the way there” tells me you’re not really having trouble getting the joints to melt, so it’s more likely incorrect technique that’s causing the issue.

In another thread, I outline the proper technique and link a video that explains it extremely well. Others in the thread describe getting excellent results using this technique with the ZD-915, too.

[…]
Regardless of which type, proper technique is essential when using a vacuum desoldering system. In a nutshell, you want to 1) fully melt the joint, such that you can feel the leg freely wiggle in the hole, 2) only then begin suction while constantly moving the component leg (this prevents it from re-adhering to the side of the hole), and then 3) keep sucking for at least 1-2 seconds longer to both cool down the joint with cool air as well as to ensure the molten solder has fully cleared the desoldering tip, and then 4) every couple of minutes, give the tool a moment to reheat a bit, so that the rear end of the tip can reheat. 

3-4 are important to reduce clogging. (If you do encounter a clog, you can often clear it by turning up the heat a bit and letting it rest for a couple of minutes.)

This 38-year-old Pace video explains the technique better than anything else I have ever found:


[…]

[msknight]

Sweat joints.... so that's the technical name.

Thanks for all this. Watching and reviewing. Would be nice to have the space for the kind of equipment they're using :-)

[armandine2]

I have just got myself a good small side cutter, Erem 670E, after ineptly de-soldering a replaceable chip.

[madires]

Adding fresh solder helps with desoldering stubborn pins.

[tooki]

Sweat joints.... so that's the technical name.

Thanks for all this. Watching and reviewing. Would be nice to have the space for the kind of equipment they're using :-)

Nah, be glad you don’t have the space, because that’s a $6000 rework system! :p

[tooki]

I have just got myself a good small side cutter, Erem 670E, after ineptly de-soldering a replaceable chip.

How is the build quality? There’s been a precipitous drop in the quality of Erem tweezers over the past few years, and I’m curious whether the same fate has befallen their cutters.

[msknight]

Nah, be glad you don’t have the space, because that’s a $6000 rework system! :p

Urk!

[armandine2]

I have just got myself a good small side cutter, Erem 670E, after ineptly de-soldering a replaceable chip.

How is the build quality? There’s been a precipitous drop in the quality of Erem tweezers over the past few years, and I’m curious whether the same fate has befallen their cutters.

No obvious sign to me of anything amiss - it came greased and with a protective plastic tube over the cutter head.

Don't know how the spring is arranged to open the jaws - but that seems to work ok, if lacking a bit of positivity.

The packaging and brochure look good.

Compared to my other small hand tools: Stahlwille flat needle nose, Lindström and Knipex side cutters, the Erem is fine.

[tooki]

The spring is inside the joint in a milled space. I’ve opened Erem pliers many times, and it’s tricky to get back together. And DO NOT open it anywhere where little parts can get lost, as there is a little metal disc that acts as the opening stop; lose it and they will open too far.

How is the alignment and precision of the cutting edges?

[armandine2]

Tooki, I've just inspected the Erem jaws under the microscope and in comparison to the Lindstrom and Knipex I'd judge it second to the Lindstrom (whose jaws look perfectly matched).

So perhaps you are on to something.