Desoldering Station ZD-915

[IngoQ]

And another recommendation: The Desoldering Station ZD-915.

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I bought mine from Amazon for around 80 EUR, which is surprisingly cheap considering what you get. It's an 80W desoldering iron with vacuum pump in the base unit. The handle is a nice pistol grip with good trigger. The base unit is made of metal and quite heavy, the handle is made of some plastic, but seems good quality. The unit comes with some soldering nozzles, cleaning wires and filters. There is a transparent acrylic tube in the handle, where the soldering tin is collected, two filters protect the pump in the base.

I desoldered a couple of ICs and through hole components with it, it works really well. Even bigger components with large copper areas around them are quickly desoldered. You still have to be careful, but it is a huge improvement in my opinion.

The base unit has a cooling fan, that starts up as soon as the unit is turned on. It's quite loud, at least for using it at home. But since you don't have it switched on all the time, this is not really an issue, at least not for me. And I guess you could always replace it with a silent one.

On youtube you can find several tests of this unit, here is one example:



Overall I can highly recommend this, especially for its very low price.

[IngoQ]

Small addition: If you are hearing a clicking noise every couple of minutes and see the display flashing, you might have an issue with the power cable.

The unit comes with a standard power cable with a C13 plug. Apparently these are wired wrongly, so that neutral and live is swapped. The internal power switch separates what should be live, but in reality is neutral. This leads to power leaking into the caps and discharging into the display.

This is a common issue in Germany, since our power plugs don't have a defined polarity. It only depends on the direction of the plug in the socket, whether you have live or neutral on one particular side. So in my case it only means, I have to turn the plug 180° to solve that problem.

But if you live somewhere else, you will need to swap the cable to a correctly wired one, to get rid of that. Or have another mains switch, that safely interrupts all lines

Source:

[Steve]

Can anyone please advise me on this... I recently did these upgrade mods to my zd915 (replace the voltage-drop resistor pack with real buck converter, add flyback diode, isolate power properly on switch) And while the machine seems to be functioning, the pump is going ... it doesn't seem to be sucking. (it does go BRRRR like it's working normally though)

I read on some of the comments of Jan Beta's video, people report that some pump motors have their polarity incorrectly marked. I didn't check mine, I just wired it up as per the red (+) sign on the motor. Now I am thinking it must be backwards?

But how can I check this? Do I put a multimeter over the motor terminals and measure resistance? What should I be looking for. (do I need to desolder the wires for this check) Then if it turns out mine has wrong polarity, do I literally swap the (+) and (-) wires and also reverse my fly-back diode polarity too?

Thanks all,

The mod video:

[stephen_usher]

The pump motor is just a motor, so if you have the leads the wrong way around it will turn in the opposite direction. The easiest test is to just swap the wires.

Jan did make a bit of a meal of the upgrades, especially the last set where he rewired things and tried to put wires in new places when all he needed to do was disconnect one wire from the motor and put the new bit in-line.

[Steve]

@stephen_usher I opened it back up and swapped it, seems to be the exact same. I suppose the pump sucks no matter which polarity you wire the motor... I thought it might blow lol. But even though it's loud, and I even overvolted it a little, the suction is absolute crap compared to before I did the mods... No idea why

[stephen_usher]

Given that this is agricultural type electro-mechanical stuff I have no idea why anyone would want to change the power supply etc. to be honest. It only needs approximate voltages to work correctly and a buck converter is complete overkill. Better a transformer and rectifier with that sort of load.

Switching both the live and neutral is overkill as well as the neutral basically goes to earth via a different channel so only the live needs to be switched.

I'd reverse the modifications if I were you.

[Steve]

I've opened it up and set the pump to 14v, it seems to be sucking better now. But yeah I don't think this mod is worth it... everyone on the internet is raving about these mods, but besides the pump action being instant, the suction seems reduced. No idea why. Perhaps the buck converter can't provide enough amps? I dunno. I'll just get a better desoldering station one day.

[stephen_usher]

Just wait, someone will suggest oxygen-free cabling inside next... so get better definition of the suction.

These are audiophile type modifications without a real understanding of what the machine does and the (wide) tolerances. After all, the motor doesn't care what the voltage is really, it just gets hotter with a high amperage. It definitely doesn't care if the power has ripple, in some situations it can help.

[Steve]

Just wait, someone will suggest oxygen-free cabling inside next... so get better definition of the suction.

These are audiophile type modifications without a real understanding of what the machine does and the (wide) tolerances. After all, the motor doesn't care what the voltage is really, it just gets hotter with a high amperage. It definitely doesn't care if the power has ripple, in some situations it can help.

I assume you know why they did these mods? It was to remove the 'step down' resistors which caused a 'lag' in the pump actuation, ie; before it had a 'ramp up', now it acts instantaneous.

That and of course, the new fan is always a nice thing. On the original wiring the fan was getting over-volted to 18v and it would then drop to 12v when the pump actuated, due to the voltage drop on the resistors.

Then there's the relay mod, which removes the pump switching from having to go through the hand-gun to the trigger-finger... this all seems like sensible stuff to me? But perhaps I'm misunderstanding.

To me it makes sense to do the mods if this is a 'daily driver' for people who do a lot of desoldering, rather than shelling out £400 for a Hakko. But like I say, I haven't had a good experience with the mods really... Not sure why, everyone else seems to love them. I'm pretty sure I've lost half my suction power.

[stephen_usher]

With respect to the fan etc. It doesn't really change the functionality. OK, having the motor ramp up more quickly is nicer but it's not exactly a real issue as you're still having to pump down the whole of the hose. But I can understand why people would want to change that. However, by ramping up the voltage to the motor more quickly you are sending a large spike of current through the windings, which may be beyond the design limit.

Not having as high a current going down to the gun has zero effect as the wiring loom is designed with the higher current in mind and you're just adding an extra component which can fail. Seeing as relays often fail by sticking in the "on" position this could actually be a bigger problem.