Replacing a budget hot air rework station: Diaphragm pump or brushless fan?

[cowana]

I currently own a Kada 852D+ hot air rework station, which I've had for around 6 years.

While it does do the task of SMT soldering fine, it's electronics are rather poor. When first switched on, the heater is powered up for around a second (without the pump) - I'd imagine this is while the microcontroller initialises (bootloader?). There is no error detection (such as a temperature sensor failure) - and the first time the heater element blew, it took out the triac and optocoupler with it.

The temperature control uses bang/bang control, which seems to be quite harsh on the elements. There is a lot of overshoot, and during operation, you can hear a very faint ticking from the element each time the power is switched back on and it's thermally shocked.

Over the 6 years I've had it, through pretty light use, it's got through 3 elements, costing around £10 each. It's frustrating coming to use the tool and finding it needs a replacement element - I can't help thinking that if it was a better design it would not need elements replacing so frequently. As I said, it has only been used lightly.

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Looking at the budget hot air stations on the market now, they seem to have more sophisticated control circuitry - an advert for a cheap 858D+ offers the following benefits over my old Kada 852D station:

• PID technology - fast heat up, rapid temperature recovery and stable temperature
• Digital display - with real-time temperature of hot air gun precisely
• Sleep mode activated by replacing the hot air wand in the stand
• Japan imported skeleton-type heater - rapid heat up, stable temperature and long life
• Intelligent self-error detection function - short circuit and overload protection

These are all features which my station doesn't have - as my current element has just blown, I'm considering replacing it with a never model. I'm happy to do the standard internal inspection required with chinese electronics, and any QC/rewiring of mains as required for safety.

There seem to be two main options, with very similar specifications. These are the 858D, and the 8508. The difference is the location of the pump - either in the handpiece (the 858D), or in the base station (in the 8508, as with my current station). The way I see, this leaves to the following advantages:

Pump in base

• Handpiece is lighter and smaller
• Quieter (I prefer a humming diaphragm pump to a wiring fan)

Fan in handpiece

• Thinner, more flexible wire to handpiece (rather than tube)
• Smaller base station
• Cheaper

Having only used a station with a diaphragm pump, I'm currently favouring this option - the thick tube helps keep it steady, and it seems very quiet. I'd appreciate any input from anyone with experience of both systems - or thoughts on the 858D or 8508D. The 'skeleton' type elements look superior to the type used by my Kada 85D - hopefully these are a bit more robust and last longer.

The sleep mode and error detection (and the fact it doesn't randomly turn on the element on powerup) all make it sound like a more sensible and reliable design - is this a fair assumption? Obviously I'm not expecting Hakko quality and might have to fix up a few solder joints before use...


Any other thoughts welcome!

Cheers,
Andy

[bobcat]

I have used an Aoyue 850 for years. It has the air pump in the base, I prefer that because the handle is lighter. It has a cooldown cycle after the power is shut off, so the heater is cooled after use. I have replaced the heating element one time. It's more expensive than some others, but you get what you pay for...

[Carrington]

If you can afford it, get an "Quick" with turbine (the 861 can be easily found in the UK).
http://www.quick-global.com/2-lead-free-rework-2.html

QUICK856AD Teardown:
https://www.eevblog.com/forum/reviews/hot-air-guns-with-profile!/msg477041/#msg477041

The 858D, is crap in comparison.