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DIY mini T2 Build Thread


mwl168
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22 hours ago, chinsettawong said:

Wow!  I tried to solder some SMD resistors today using solder paste and hot air.  It’s so difficult!  I turned the air down to the minimum already, but as soon as the solder started to melt the resistor got blown away.  Is there any good tip for a beginner?

I did some experimentation and found that low airflow and fairly high air temp worked best for me.

I have a quick 861dw hot air station. I set the airflow to 5 out of 120 and set to 360C (the temperature will depend on your solder paste melting point). I hold the hot air nozzle with one hand and with the other I use tweezers to keep the smd part in place. If you do not hold the part in place almost any airflow will send components into low earth orbit. The tweezers I use are curved on the end which makes it easier to place components, keep your hands away from the heat and easier to see what's going on.

 

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Edited by jamesmking
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I always do smd soldering with fin tip solder iron and after a long time of practicing I feel quite comfortable with that. I’ve tested with hot air station and with proper amount of solder paste on the pads and when using low air flow I managed to solder without components blowing away. And it’s a nice feeling seeing a component nicely aligning up on its pads.  But I prefer the soldering iron technique. Me and solder paste don’t mix well. After a while the whole table is a mess and I even have solder paste on my nose.

With some practice I’m sure everyone can do smd soldering, but it can be very frustrating initially. 

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I use an oven (when it’s not too cold outside) and a hot air station during the winter. 

I agree that you need to set the air velocity way down.  I do keep a tweezers handy in case something moves or tombstones, but I generally don’t need it. 

Try to have the air gun directly over and perpendicular to the parts. I move it around in small circular motions anywhere from 12mm - 25mm above the parts. 

It’s very important that the parts are somewhat centered in the pads. For 0603 and down, I use a loop while I’m placing the parts. 

Once you get the hang of it, it’s a very fast way of soldering. 

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Posted (edited)

To date I've soldered all the SMD applications using a fine-tip soldering iron and a fine tip tweezer. I also find using very small gauge solder is key - I use .02"/3mm diameter solder from Kester with 2% silver and it works great. You can get a small tube of this solder from Mouser offered by NTE. I can try dig out the part number if you are interested.

I want to experiment with a hot air station but have not done so yet. Mostly because I could to decide how much to spend and which one to get. Even the very basic one from the trusted brand (JBC, Hakko, etc.) costs an arm and a leg. 

Edited by mwl168
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15 minutes ago, mwl168 said:

To date I've soldered all the SMD applications using a fine-tip soldering iron and a fine tip tweezer. I also find using very small gauge solder is key - I use .02"/3mm diameter solder from Kester with 2% silver and it works great. You can get a small tube of this solder from Mouser offered by NTE. I can try dig out the part number if you are interested.

I want to experiment with a hot air station but have not done so yet. Mostly because I could to decide how much to spend and which one to get. Even the very basic one from the trusted brand (JBC, Hakko, etc.) costs an arm and a leg. 

the quick 861dw comes highly recommended 

 

 

 

its also useful for drying out pcbs after ultrasonic cleaning, removing surface mount components, heat shrink etc.

 

 

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Michael,

Check out the Rossman group videos on YouTube. He does a review of some hot air stations. He likes the Quick, but I believe he has one from Atten which is cheaper and performs just as well.

 

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Thanks for all the good advices.  I change the air nozzle to a bigger one so that it has slower air velocity, and set the temperature to a bit higher, and now it goes a lot better.  :)

I still have a long way to go though.

By the way, the smell of the flux is really bad.  Do you guys wear a mask or use a filter fan when doing the hot air soldering?  

 

Edited by chinsettawong
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  • 3 months later...
On 4/8/2020 at 5:45 PM, JoaMat said:

Now when Kerry regulators and psu board are on its way I and maybe a few other builders wonder what transformers might be appropriate.

Will Kerry publish his new mini T2 PSU? That would be awesome!

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16 hours ago, Kerry said:

There was a group buy for this already. You should be able to find what you need there

Hey Kerry, I have typed this wrong. I know the GRHV/LV from within the mini T2, I was thinking about your later and scaled down real T2 PSU. 

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I don't have a scaled down T2 PSU.  The one I use is based on the original T2 PSU schematic.

I am working on a golden reference version, but that project is not completed.

Once upon a time, I did a golden reference version, but it was too fragile.  In my new project, I will add current limiters in front of the regulators, like Kevin did in the T2 PSU.

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  • 3 months later...

Hey guys. New and utterly uneducated on electrical engineering. Is the mini T2 a shrunk version of the T2 or a new design just based on the t2 topology? I have been drooling over a t2 for ages but have some space tight constraints (mostly footprint) and most of this thread has been over my head so I couldn't figure out the answer 

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joamats mini t2 with golden reference psu only uses modern and available components. The amp boards are mostly surface mount and the components are fairly tightly packed. Its based on the t2 topology but simplified and runs at lower voltages and has less voltage rails, no virtual batteries and less current sources. The mini t2 still requires a fair bit of space. I got the amp boards, and the three golden reference high voltage power supplies, the high voltage delay board and low voltage power supplies in a 2U case 400mm deep. The mains transformers had to go in a separate case... So even the mini t2 might be too big for you. Although you could make the main amp smaller by putting the power supply pcbs in the same case as the transformers. I don't think you could fit everything into a single 2u case 400mm deep.

Both the original and mostly modern t2s are gigantic partly due to the many different psu rails and the considerable number of constant current sources on the amp boards. I had to make the amp board smaller just to fit it in a 2u 400 deep case and the many psu pcbs and transformers had to go into another 2u 400mm case... My T2 is twice the size of my main systems power amp!

The original diy t2 uses many transistors that have been unavailable for many years and so are expensive and difficult to source. the markets are also flooded with fakes which will almost certainly fail on first start-up

the mostly modern t2 requires a few out of production transistors.

Its possible to build an entire blue hawaii with golden reference low and high voltage supplies in a single 2u 400mm case. So if space is a real issue that might be an option for you and the later versions only use modern components and is a much simpler and cheaper build than a full t2.

 

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