My KH228 solder paste dispenser - Part 1 (Beware of Chinese tools)

Found this bargain on EBay - a pneumatic solder paste dispenser for around $100!

Mine came exactly like this one, except for the shot time controller - apparently mine is an Omron (or more likely a Chinese timer branded Omron!).

I always have a look inside any cheap tool that connects to the mains before I plug it in - this time my paranoia might have been justified.

I was surprised by how neat the insides are, it is a very simple device! It has nice push-in hose lock connectors for all the air hoses, a solenoid with sold metal base, a hefty looking digital timer which is connected to a re-wirable base (not soldered directly), a large relay in a base and a generic looking regulator and pressure valve. 

Pity about the wiring side of things! All parts run from 240v and none of the connectors are insulated (except for the powder coating on the case - which is very neat an thick), no chassis earth(!) and the craziest bit - the foot switch connector has easily touchable exposed pins! One of these pins connects to mains neutral, the other connects through the relay coil to active - I'll be sure to have that connector connected before I apply power!

A small mod to add a chassis earth and I'll feel safe enough to give it a bench test with the lid on (being careful of that foot switch connector!).

It works! Here it is with the timer running for a 0.32 second shot. There was no air connected for this test but I have since charged it and there are no leaks internally - the hoses that connect to the air inlet and outlet connectors did need some modifications. I've found that black polytube used for garden sprinkler lines fits the connectors perfectly and is easily heated and moulded. By scrapping the plastic connectors that come with the hoses and using this tube directly the lines hold 80PSI with no leaks.


Dispensing solder paste is now quick and fun! What a great idea!

Check back for upcoming parts on alternative pressure sources and possible upgrades / rewiring.