Test rigs

I was going to post a reply on the following thread

http://www.ukwhitegoods.co.uk/modules.p … highlight=

But thought that a new thread would be better regarding stripping wiring harnesses out of scrap machines for test purposes.

I have quite a few of these test rigs as they are very handy for testing any machine componants but especially motors and modules. I remove the harness from a scrap machine with all the bits and pieces left in place (except the motor and pumps).

Once on the bench i split the harness and seperate the wires that feed each componant. You now have a choice of shortening each set of wires using bullet connectors or simply coiling them around your hand and tying with a tie wrap or tape. The only one i usually leave intact is the motor harness. You should now have a very compact test rig. Make sure that you have detailed notes of where connectors fit especially on computer type modules should you not use it for a few months.

On computer machines I leave the control panel connected to the harness on machines like Ariston / Indesit / Hoover (where there are lots of wires to seperate switches, LED’s and selector switch)

or seperate ie. Zanussi (a small single IDC connecting harness)

or on the WMA where everything – switches, LED’s etc is on the module it can even be used without the front panel.

I have a set of neons with male connectors which I substitute for the valve solonoids & heater to monitor their on/off states. A piece of rubber tube on the pressure switch(s) with something to stick in the end to hold in the pressure. All you now have to do is emulate the program sequence manually where required. As most machines now use NTC thermistors you may want to test the heating circuit. This is best done by substituting a variable resistance set a little lower than that required for the equivalent temperature you are testing.

I have done temperature / resistance plots for a few different thermistors including Hoover, WMA, Merloni and Zanussi which I will make available on the forum if required.

Some machines that use a microcontroller don’t like having certain componants (usually pumps) substitued with neons (possibly because they have the ability to sense the inductive load to test for o/c condition), but valve coils and heaters seem OK.

Also make sure that you use the mains filter on computerised machines to ensure a clean supply, otherwise you may be troubled with processor resets / hangs.

I mainly use my rigs for testing modules after repairing them but they are very handy if you want to test a module or motor to eliminate it as a suspect or any componant for that matter.

An hour spent stripping out and preparing the test rig is a good investment when you consider how much money you might save on wrongly ordered modules etc!

Andy 🙂