Cheap Desoldering station upgrade, now sucks even Harder! No really!

[djos]

G'day all, I've always been mostly happy with my cheap ZD-917 desoldering station, (there's a heap of other companies selling the same product in a standalone unit too - desoldering guts are the same), but always thought it could be even better ...... and it can! 

Today I finished upgrading mine - there's 2 parts to this upgrade, forcing the pump to always run and adding a tiny electronic air valve inside the handle. Here's some pics I took during the upgrade:



The vacuum tubes aren't a tight fit so i added some silicone and then zip tied the tubes on - they are very airtight now!


I added some silicone to hold the valve in place and prevent it from jumping around inside the casing under load.


yes, it all fits (after breaking out a plastic tab and removing some unneeded rubber jacket from the wiring)




and fully reassembled!


after cutting the wires to the motor, I used a terminal block to wire the motor to always on and wired the gun-switch in parallel so it could steal 12v for the air valve.
NOTE: the motor is wired opposite to how it's marked (-/+ are swapped).


I added some yellow electrical tape to the metal frame as the edges on it are a little sharp and I didn't want the wiring etc getting damaged in the long run.


Just finished testing!


and a bloody good result! this 62 pin header came out out with very little effort! I'd tried to recycle a bunch of these previously (the header is the wrong spec) and ended up destroying the pcb's!


and back in her home ready for more action! 


The parts I used are as follows:

• 12v normally closed air valve
• terminal block
• 2 extra pieces of wire
• heat shrink tube

So this cost me about $5 AUD I reckon and the performance is dramatically better, Im really blown away by how much better it is, and I was expecting an improvement! 

[aargee]

Great mod!

So what happens is the pump pulls full pressure, and opening the valve produces a pulse of full vacuum at the tip, increasing the effectiveness of solder removal?
This as opposed to the ramp-up vacuum normally produced when you hit the trigger..

Do you think the vacuum pump will hold up to continuous operation?

[djos]

Great mod!

So what happens is the pump pulls full pressure, and opening the valve produces a pulse of full vacuum at the tip, increasing the effectiveness of solder removal?
This as opposed to the ramp-up vacuum normally produced when you hit the trigger..

Do you think the vacuum pump will hold up to continuous operation?

Thanks mate. 

So basically the pump runs all the time and creates a pretty strong vacuum in the length of the hose - when you pull the trigger, voltage is applied to the normally closed valve opening it. This creates a virtually instant and strong suction force at the tip and pulls the solder out cleanly.

Previously the suction force took time to build up and the solder joints didnt get cleaned out as effectively as they do now.

I'm not concerned about the longevity of the pump - in general use I've never left it running when not in use as there's no half-power sleep mode on it.

[djos]

Btw, the guts of Dave's desoldering station and the gun itself are close enough to the desoldering station half of my unit - so the mod should work just fine on his model.

https://youtu.be/Ft50m8UU5WQ

[texaspyro]

The Pace desoldering tools use a technique they call "SnapVac".  When you pull the trigger they first drive the motor with (24V?).   Then they back off to the normal motor voltage.  This works very well.

[djos]

The Pace desoldering tools use a technique they call "SnapVac".  When you pull the trigger they first drive the motor with (24V?).   Then they back off to the normal motor voltage.  This works very well.

Interesting idea - i've heard some of the expensive units have spring loaded valves so once pressure builds up enough, the valve opens producing a nice strong instant vacuum. I did toy with the idea of building a relay circuit with a delay that turns on the motor and then 1/2 a second or so later opens the valve ..... TBH I might still do this.   

[beanflying]

Interesting idea.

It should be able to be added to my Aoyue/Hanba/(insert your clone here) even if the solenoid won't fit in the gun it could sit outside on the hose with a bit of support.

Maybe add a pump toggle switch on the base station to prolong the diaphragm life but still allow the tip to preheat and enhance the serenity between sucking? A Delay would drive me nuts doing a run of desoldering.

[djos]

Interesting idea.

It should be able to be added to my Aoyue/Hanba/(insert your clone here) even if the solenoid won't fit in the gun it could sit outside on the hose with a bit of support.

The mod is dead simple and will work on them all I reckon. just get the little one I linked to and it will fit inside the gun making for a nice stealth mod.

Maybe add a pump toggle switch on the base station to prolong the diaphragm life but still allow the tip to preheat and enhance the serenity between sucking? A Delay would drive me nuts doing a run of desoldering.

Oh that's a great Idea ... I might just add that to the front panel to turn the pump on and off as required. 

[beanflying]

You could also get a gain of rapid volume by adding a reservoir to the system. Could be as simple as a loop of larger diameter hose placed on a T piece broken into the main line before the pump. It would just need to be crush/vacuum proof.

[texaspyro]

I think that running the pump continuously is a bad idea.   The pump motors (and pumps) don't seem to be rated for continuous duty and tend to run hot.   It looks like they are already somewhat overdriving the system.

[djos]

Maybe add a pump toggle switch on the base station to prolong the diaphragm life but still allow the tip to preheat and enhance the serenity between sucking? A Delay would drive me nuts doing a run of desoldering.

Just dashed out to the workshop and added a switch - it was too good an idea to ignore. 

[aargee]

You could have a double action circuit that powers the pump for a few seconds, then triggers the solenoid then off.

[djos]

You could also get a gain of rapid volume by adding a reservoir to the system. Could be as simple as a loop of larger diameter hose placed on a T piece broken into the main line before the pump. It would just need to be crush/vacuum proof.

It's not really needed, there's more than enough vacuum built up in the hose and it recovers extremely quickly - I had zero issues desoldering that 62 pin header and I consider that to be a heck of a torture test. The whole point is to get that snap suction action and my mod definitely achieves that.

[djos]

I think that running the pump continuously is a bad idea.   The pump motors (and pumps) don't seem to be rated for continuous duty and tend to run hot.   It looks like they are already somewhat overdriving the system.

I've added a switch so I don't have to de-power the entire desoldering station - TBH it was mainly the noise that was annoying me. I'm not concerned about reliability, the pump really isn't working that hard.

[Ranayna]

Very nice. I have a ZD-915, so just the desoldering part. Have not used it much, but already had to deal with clogging in the handle. I suspect the stronger vacuum application would help prevent clogging?

Just out of curiosity, I could not see it in your pictures. Do you know if the power switch in your model switches only the hot side? My ZD-915 only switches one pole. I live in Germany, and we have unpolarized plugs. Depending on the orientation of the plug, the ZD-915 occasionally "blips" even when turned off. I assume it is related to leakage in what I assume is a switch mode supply when neutral is the switched pole.
The switch in my unit even has two poles, and the other power cable is accessible, so I can't understand why they have not wired it in...

[djos]

Very nice. I have a ZD-915, so just the desoldering part. Have not used it much, but already had to deal with clogging in the handle. I suspect the stronger vacuum application would help prevent clogging?

Cheers. I find that you need to keep the trigger pressed long enough that it has enough time to pull all the solder into the glass tube, then it doesnt clog up.

Just out of curiosity, I could not see it in your pictures. Do you know if the power switch in your model switches only the hot side? My ZD-915 only switches one pole. I live in Germany, and we have unpolarized plugs. Depending on the orientation of the plug, the ZD-915 occasionally "blips" even when turned off. I assume it is related to leakage in what I assume is a switch mode supply when neutral is the switched pole.
The switch in my unit even has two poles, and the other power cable is accessible, so I can't understand why they have not wired it in...

It is only a single pole switch so yeah it'd be the hot side only - our Aussie plugs can't be inserted incorrectly so as long as your house or workshop wiring is to code that should be good enough (imo).

[TheNewLab]

when I look for your ZD-917 unit for sale, I only find the gun only..Where did you get the full unit?

[djos]

when I look for your ZD-917 unit for sale, I only find the gun only..Where did you get the full unit?

I've had mine for a few years now, but I bought it on ebay in Australia.

Just look for desoldering station and look for anything that uses the same gun, there's really no significant difference between them all.

[Gyro]

You could also get a gain of rapid volume by adding a reservoir to the system. Could be as simple as a loop of larger diameter hose placed on a T piece broken into the main line before the pump. It would just need to be crush/vacuum proof.

Combine that with a vacuum switch to cycle the pump as needed and you've really got something there.

[djos]

You could also get a gain of rapid volume by adding a reservoir to the system. Could be as simple as a loop of larger diameter hose placed on a T piece broken into the main line before the pump. It would just need to be crush/vacuum proof.

Combine that with a vacuum switch to cycle the pump as needed and you've really got something there.

I've added the switch at the suggestion from others but the reservoir is not needed as what you need, imo, is just rapid vacuum recovery before the next pin is desoldered. This is all about getting a rapid pressure change at the tip which rips the solder out in one go.

[macboy]

I think you could achieve a similar effect by having the valve activated on a delay relative to the motor. Even less than one second would help a lot. Then you would have the motor only running when needed, and still have "snap" action vacuum.

[glarsson]

Also keep the pump running for a couple of seconds and don't delay the valve if the pump is already running.

[SeanB]

Must look into getting one of these, i can then add that vacuum booster as well, as I have all the parts needed, thanks to having taken apart a Tektronix Phasor printer, which uses a similar vacuum pump and reservoir and valve to clean the print heads.

Only thing to add would be a small in line fuel filter, so the vacuum valve does not get clogged, which makes them leak, and these little ones are not terribly amenable to being taken apart to clean the internal parts. Go to auto parts store and ask for the smallest inline fuel filter they have, generally one suitable for a 1966 VW beetle will work, as they did not come with one ex works, and the little dinky inline 6mm one was a common upgrade for them. small filter before the valve, and then get a humongous 6mm Toyota Hilux fuel filter, which also makes a very good vacuum reservoir.

With this probably a good addition would be a off delay timer to control the pump. Tap the switch and have the pump running for 30 seconds, so you can have good vacuum all the time, but when you stop the pump only runs for 30 seconds extra. Generally you will just wait 10 seconds after the first tap, then desolder fully.

[james_s]

You could add a vacuum switch that runs the pump only as needed to pull a vacuum in the line. That would probably increase the lifespan of the pump, and certainly reduce the annoying noise. At that point you might want a small reservoir too, I don't really know.

[djos]

I think you could achieve a similar effect by having the valve activated on a delay relative to the motor. Even less than one second would help a lot. Then you would have the motor only running when needed, and still have "snap" action vacuum.

Agreed, I am considering doing that next year when I return from holiday with the family.