Are some components spot-welded to the MBs?

[dellxps15]

Re: Are some components spot-welded to the MBs?

keep in mind that with low budget hot air station, the nozzle must be very very close to the ic to heat it well.

if u have a screw to regulate the power of hot air, try to make the hot air more hot as u can. also when i desolder some good ic on some macbook board with low budget hot air as atten 8586 i go even to 440° to remove if after around 3 minutes and without flux is even harder to get it off

[paulo66]

Re: Are some components spot-welded to the MBs?

I like the parts where the video is edited to make the Quick finish quicker than the Atten. Heh

Again, I've desoldered all kinds of mosfets including dpaks, qfns, bgas, you name it with this rebranded atten. It's not that bad. But it's far from perfect I reckon.

Except for all the bells and whistles, what do the Quick and its knockoffs have that a Hakko 858 clone doesn't?

[paulo66]

Re: Are some components spot-welded to the MBs?

Btw the fan was clean as a whistle. The lube looked rancid and I cleaned it up. It now just needs a drop of oil.
Tested the full air flow at 100 C, it's nothing but a light breeze. Disappointed.

[dicky96]

Re: Are some components spot-welded to the MBs?

@paulo66
The 858D is not bad, I totally agree - I have one myself and used it for 2-3 years

But the Quick is a totally different beast. I have one of those as well. And since then haven't used the 858D, there is just no reason to. Actually come to think about it I may as well sell it.

So in all honesty, I've used them both extensively and can speak from personal experience - and I can tell you there is a big difference.

If Dave @eevblog didn't convince you there are hot air stations, and then there are HOT AIR stations, have a look at what Louis thinks.

https://www.youtube.com/watch?v=ChujyTV-HME
https://www.youtube.com/watch?v=wYCmU6jMLo8

Or just go with your own opinion, though if you haven't tried both I am not sure what that could be based on.

[paulo66]

Re: Are some components spot-welded to the MBs?

My bad I meant Hakko 850. How does it compare? It looks like a classic design. Rugged industrial look, functions reduced to a bare minimum.

@dicky96 I appreciate your recommendations.
It was Dave's review that made me choose the 858. I like the build quality of the Quick and that will probably be next. Or the Atten or the Best or a clone of the spartan 850.

[piernov]

Re: Are some components spot-welded to the MBs?

My personal experience is that my Yihua 898D (858D with a completely useless soldering iron) was garbage, unreliable, a safety hazard and I can't recommend it to anyone after struggling 3 years with it.
Fan dying, bad contact in the cables (both hot air handle after replacing it due to the fan and soldering iron handle after replacing it due to plastic breaking, receiving one that didn't work at all in the process), soldering iron handle crappy plastic breaking twice (it has a plastic "nut" between the handle and the heating element just before the metal nut, gets cooked with heat and breaks when applying just a bit of pressure), hot air handle starting to melt, the pins of the mains plug just breaking…
That's on top of having shitty airflow and thermal regulation that could give +100°C one day and -50°C the other, causing it to have a noticeably harder time with dealing with high thermal mass, require higher temp and much more time than a good hot air station.
Yes I did manage to repair some stuff with it, but I killed others things and it could have started a fire. Definitely not worth the risk.

My Quick 861DW is perfect for what I do. The fan may be unreliable by design and some people that have been using it extensively have reported failures, but that didn't happen to me since I don't use it all day long. IIRC other similar stations like Atten ST-862D don't have this problem.

To each their own I guess.

[paulo66]

Re: Are some components spot-welded to the MBs?

The quality of the 858s seems to vary widely between brands and models. I guess I have been lucky with my ProK.

I´m a stubborn cheapskate. If I have to work three days off to afford a Quick then I´ll play devil's advocate until I´m convinced.

Nothing like it in the local market except a clone of the Hakko 850 from Aouywe or something for 149.99, with added soldering iron that looks like the one found in the 936 clones. Which means: crap. I´ll have to shop online.

[dicky96]

Re: Are some components spot-welded to the MBs?

@paulo66
Out of interest, what would convince you?

[paulo66]

Re: Are some components spot-welded to the MBs?

Forget it. I´d better return to servicing vintage synths. All thru-hole and double-sided boards at most. None of this super i/o qfn megagroundplane !"#$% and better grab the money and refund the owners of the motherboards that I´ve just !"#$%

Fucking planned obsolescense they dont want you to service their products

Sorry for the rant. You all have my respects Sirs and good luck with your carreers.

[piernov]

Re: Are some components spot-welded to the MBs?

Stopping killing chips and boards and avoiding safety hazard should be convincing enough.
Although I can understand what you mean if it's just a hobby and you don't make any money from it (and rather lose money). I'm in this situation and I am cheap as well.
If you're a business doing this professionally it's not acceptable in my opinion.

[dicky96]

Re: Are some components spot-welded to the MBs?

Ooops!

[paulo66]

Re: Are some components spot-welded to the MBs?

No, this time it was the microsoldering.

[dicky96]

Re: Are some components spot-welded to the MBs?

Actually Paulo, there is another issue of technique here. I didn't really think to mention it and come to think of it I'm surprised now do one else did

Looking at your pic on the first post - what is all that metal foil around the component you want to desolder? I'm guessing you put that there to protect other nearby components (yes?), which seems a perfectly reasonable thing to do if you are not experienced with this sort of rework.

But let's consider this logically and scientifically. To be honest your 858D should be able to desolder that MosFET (at least it looks like a MosFEt) but it isn't.

There will almost certainly be a central metal tab underneath the component that is soldered to the board (ground) so you need to get the ground plane and the component hot enough to desolder it. As this is probably a power component the ground plane in that area of the board is likely to be heavy and capable of sinking a lot of heat.

So do this you need to get plenty of heat into the ground plane by heating the whole general area of the PCB - the technique is to hold the hot air a few centimeters above the board with a large nozzle and swirl it around heating the area for a couple of minutes, then zoom in on the component you want to remove and hold the hot air very close to the board until it desolders.

But think about what you did, you put a lot of aluminium tape around that area which prevents you from heating the ground plane! So you are defeating your own object here and making life difficult. In fact you are probably stopping yourself from desoldering the component.

If you have seen Louis Rossman and others working on youtube - do they put foil all around the area they are tryign to rework? No they don't.

https://www.youtube.com/watch?v=wYCmU6jMLo8
17min 23 secs

Do the nearby components blow away? No they don't. Do they burn the board, No they don't

Part of this is down to experience and it is always good to practice on a scrap board or three first . but to help yourself while learning, get a thermocouple and temperature meter for less than a cheapskate price. No, in fact get two of them. These are the ones I use

https://www.aliexpress.com/item/3261...archweb201603_

They are €4 each inc postage - is that cheap enough?

Also get some Kapton tape (the proper stuff not the sh!t fake that shrivels up when it gets hot) and tape a thermocouple to the PCB on either side.

One on the top near the the component you want to remove and the other one on the underside of the PCB, preferably directly underneath the component

Put some flux on the part you want to remove, like Louis does. Use this flux, it is almost certainly what Louis uses, and it is what I use, and plenty others here too.

https://www.aliexpress.com/item/3278...archweb201603_

Get rid of all that aluminium shielding tape!

Now you can do the preheat - swirling around the hot air. You can see the topside temperature and the bottom side too. The idea is to get the heat into the board so the bottom side rise up to 100C-150C without the topside getting to hot in the process. This takes time, so patience is a virtue here. Also feel free to warm the PCB from below too.

Once you have a nice temperature into the ground planes, move directly to the faulty part and get the heat gun close to it and hold it there. It should now desolder in maybe 30 seconds or so.

It is unlikely you will blow nearby components around the board (but I always take a pic of that area of the PCB first so I can check afterwards). This is because the surface tension of the molten solder holds them in place better than you may expect.

It is more likely you will disturb nearby components when you lift the faulty part with tweezers. This is down to technique and practice. But if you take a photo first as I suggest you should be able to move the other components back into position.

So that's my cheapskate guide to what you are doing. I hope that helps and you don't think 8 euros is too much to spend on kit.

Rich

[piernov]

Re: Are some components spot-welded to the MBs?

Yes that's right, better not add additional thermal mass if it's not needed.
If you have connectors or aluminum electrolytic/tantalum caps nearby it is preferable to put a shield on them though, and indeed it'll take a bit longer to remove the chip but should still not cause too much trouble.

[paulo66]

Re: Are some components spot-welded to the MBs?

Rich, the metal foil is aluminium sticky tape from Tesa; it sticks better than (genuine) kapton tape. Yes, it´s used as a shield to prevent nearby components from flying off the board. The mosfet I tried to remove is in the "high" position, so its central tab is connected to the B+.

Sorry. More later, I´m at work.

[paulo66]

Re: Are some components spot-welded to the MBs?

Your suggestion of using a pre-heater + cheap hot air or pre-heater + not cheap hot air is excellent. Pre-heaters aren´t used solely to prevent thermal schock and warping and breaking of the PCB.

They spread the heat to the ground planes and other areas. I used to warm up the board only for a few seconds and always around the component about to be removed. I´ll give another try.

Already got multimeter with thermocoupler.

@piernov I still don´t think the aluminium foil adds much thermal mass. It would if it was fully in contact with the heating area, but the surface is very irregular so there´s lots of air between. The few points of contact work like thermal relief in PCBs.

The lack of thermal relief pads and islands on the PCBs tell they don´t want us to fix their motherboards.

[dellxps15]

Re: Are some components spot-welded to the MBs?

how old is ur hot air station? mine is almost 5-6 years old and i noticed it was not working like when it was new.... so i replaced the heating element, but looks like it do the same... even if i put 400° and airflow 7 it make airflow go from 7 to 4 at some point.... maybe my fan, somecalibration or just aging made it not good annymore.

tomorrow ill see if the screw is setup properly.
almost none component is welded to the mainboard, it's just the temperature , the time or equipment not good enought. in the past i did many mxm vga bga replacement, and some of them need more heat, more time and more higher temprature to melt. maybe different solder material, bad pcb absorbing heat or any other thing , but also on that time i had to get used to them. also macbook need way more heat to remove a single ic or component.

[paulo66]

Re: Are some components spot-welded to the MBs?

Mine must be 3 years old. It's from ProK, the "standard" brand of all cheap stuff. Formerly Pro´s Kit.

I´m speculating each time you see some new product of some unknown brand it´s "them" testing the waters. If the product sells, expect a stampede of other chinese brands, such as Yuhan, Atten, Aouye etc with identical products. Each with their own criteria of what build quality is. Finally ProK arrives and sets the standard.

It was always a bit slower than the "proper" hot air stations (seen on Youtube) to desolder any component, but it always did the job. Until now.

Yes, maybe it´s out of calibration or it´s time to buy a new handle or a proper tool.

[dicky96]

Re: Are some components spot-welded to the MBs?

Hi Paulo.
Cheers!
Yeah (cheap) preheaters are kinda the holy grail to making this sort of rework possible. Yes with experience you can do it without, but it is much easier, though a bit more time consuming, to use the preheater. I have one of these
https://www.aliexpress.com/item/3280...archweb201603_

And it is very good for this sort of rework.

I also have a much more powerful one on my BGA rework staton but that is a different topic.

Regards this
'@piernov I still don´t think the aluminium foil adds much thermal mass. It would if it was fully in contact with the heating area, but the surface is very irregular so there´s lots of air between. The few points of contact work like thermal relief in PCBs.'

And this
'Yes, it´s used as a shield to prevent nearby components from flying off the board'

Honestly Paulo, nearby components will not fly around the board. You need to practice a little on scrap boards until you are convinced of this fact. You are far more likely to dislodge nearby components when you use tweezers to remove the component you want to remove, and you skew it sideways, or drop it where you shouldn't. But blow them around the board? Not likely.

This is not a difficult skill to learn but like everything else, it does take some practice. So do yourself a favour - find a scrap motherboard and play around with your hot air. Or get a scrap board from ebay or somewhere for a few euros and gain some useful FETs and capacitors for your spare components box while learning

Also try with different hands, if you are right handed like me try holding the hot air in your left hand and the tweezers in your right - but in the end find which way works best for you. in my case, against my preconceptions it ended up hot air (or soldering iron) in right, twezers in left - but we are all different.

But honestly mate, you need to remove that shielding - not so much for reducing thermal mass, but because it is not actually in contact with the board, it is insulating the board from the heat, reflecting back the heat and keeping the ground planes cool. This is the opposite to what you need to happen.

Or yes, use a preheater under the board, then you can work from above with the perceived safety belt of the aluminium shielding...... possibly

[ktmmotocross]

Re: Are some components spot-welded to the MBs?

If u dont remove mosfet with cheap station i bet is short-welded to pad. I was using cheap 20euros hot air from ali nearly for two years on daily repair of 2-3 laptop WITHOUT ANY ISSUE