Clarke 100E MK2 - No Wire Feed

[jazzy]

My old trusted Clarke 100E MK2 has finally packed in after over 20 years service. The problem is that there is no wire feed, motor relay is clicking and making a good contact but there is no voltage at the motor. The motor is working fine with a 12v supply. So chances are it's one of the PCB components. The PCB is part number E1285.1, which is a different board than most other Clarke owners have (looking for similar problems on this forum).

What is the most common PCB component that fails on these models? or any other suggestions what may be causing the problem?

 

[GrahamGKD]

I don't have any knowledge of this specific machine but does the relay drive the wirefeed motor - if so, have you got some voltage one side of the contacts before it clicks and both sides after - i.e. could it just be burnt out or dirty contacts?

D'oh, just re-read your post - I guess by saying 'making good contact' you checked that, so, no voltage to either side of the relay before it switches then, I guess?

 

[the snooper]

is there power at the torch if you pull some wire out will it arc up

common faults are

bad connections inc welding transformer
relay
pcb transformer
then components on the board check diodes and alike first the it would be down to the transisiter on the heat sink

 

[the snooper]

it is looking a little sutty around the relay

 

[jazzy]

is there power at the torch if you pull some wire out will it arc up

Just put the PCB back to test if there was power at the torch, and it's all working again! Checked for dry joints, but they all appear ok.
So I will wait to see what happens after a bit of use..

 

[Wedg1e]

it is looking a little sutty around the relay

Agreed. Those relays can be dismantled for cleaning: carefully unhook that spring from the top and you can lift out the swinging contact carrier. The contacts should all be clean and shiny with a slightly-domed surface. I bet they're not (or some of them at any rate). They can be cleaned with miniature files, emery boards or diamond files, but aim to recreate the slight domed shape. If the contacts are badly pitted then no amount of filing will reshape them and in fact it's only a matter of time before they'll be fuackered again - the contacts are usually plated with something like Rhodium which helps to slow down the rate of decay due to arcing across the contacts. Once it's gone, the base metal will just keep vapourising.
Best fix is a new relay! It looks to be a Finder DC type (AC ones have blue coils as I recall), DPDT or 2PCO as it's sometimes called. Coil voltage (probably 12v) will be stated on the coil.