Mig wire speed running too slow

[mike 109444]

As the track inside the pots is little more than a coating of carbon then cleaning may only be a temp fix. You need to look at the values printed on the post and for what they cost, replace them.

 

[James Paul]

 

[Seadog]

That looks like 100kΩ

It'll be a log pot if it's a carbon track. In fact, for that sort of value it's pretty certain to be log.

 

[James Paul]

The latest on my Clarke welder with the wire feed mechanism running too slow.

I desoldered the three wire feed speed pots and took them out. I then sprayed contact cleaner on them from every angle and resoldered them back in. This has given a good improvement but still getting occasional slowing. Can the pots be replaced? What are the revelvant numbers. See photo. Where can I get them? Thanks.

 

[mike 109444]

Fill yer boots
https://www.ebay.co.uk/sch/i.html?L...id=m570.l1313&_nkw=variable+resistor&_sacat=0

 

[James Paul]

I’am having trouble identifying which trim pots I need to buy. I’ve attached photos of the original ones. Could someone give me a few pointers. I don’t fully understand the technical description which is given for the pots on eBay. Do the pots need to look the same as the ones that were already on. The three prongs need to be in the same place, but can I use a square shaped pot or a different colour. I don’t know if the shape or colour indicates anything about its function.

Does the figure for the resistance need to be exactly the same?

Thanks.

 

[Seadog]

2.2kohm, 47kohm and 100kohm.

 

[James Paul]

I am having difficulty obtaining the right pots. Every time I order, they turn out to be the wrong size or the wrong value. Could anyone help with getting the right ones.
Thanks.

 

[mike 109444]

It should be possible to bend the pins of a pot that is physically to big (or even to small, not so easy) using needle nose pliers to match the holes in the pcb. Physically bigger pot would/may have a slightly higher power rating (but not that important in this application. Don't use/get the square ones with what looks like a small brass screw (to much faffing to get into pcb correctly!). The main thing is to get the correct VALUE as in say a "2k2" or "100k!
If you follow this link to ebay item https://www.ebay.co.uk/itm/5x-Trimm...491360?hash=item46403da0a0:g:3kIAAOSwLVZV4HtX
You will see about half way down the page on rh side there is a "down load full datasheet". Click this and the pdf doc will show LOADS of stuff you don't need to know! BUT on page 2, lh side "mounting methods" the V10 and V5 images give an indication of the dimensions between pins that are used/needed when determining what pot you have.
Hope that helps.

 

[James Paul]

Thanks mike. How close do I need to be with the value? For instance, would a 50kohm be near enough to stand-in for the 47kohm. I think I now understand how the pin dimensions work in the piher brand, but will I be able to get the precise value I need without having to use a different make of pot?

 

[mike 109444]

The difference between 50k and 47k should not make a great deal of difference (these are not precision machines!) Most manufactures work/make the standard range of pots. Manufactures build circuits around commonly available parts where possible and most of the parts (resistors ect) have a +/- tolerance any thing up to 20%. There are very high precision components but not needed in something like a welder!

 

[James Paul]

I changed two of the trimpots. On the above photo of the pcb, they are marked v.max and v.min. I then checked the wire feed speed mechanism with the speed turned all the way up and it seemed to be running much faster than before. When I adjusted the white arrow in the centre of the trimpots, it made no difference to the speed.
I’am not that concerned because I can adjust the speed with the wire speed knob through a good range from very slow to very fast, so I should be able to weld with it ok. Although I would be interested to know why adjusting the trimpots didn’t make any difference to the speed.
Thanks.

 

[bwservices]

the vmin will ONLY adjust the minimum speed
the vmax will adjust the max speed

combining the two gives you range and speed sensitivity

 

[James Paul]

What does the third trimpot do? In the photo of the pcb, it’s marked- RAMPA-.
Thanks.

 

[bwservices]

its how quickly the wire feed reaches the set speed
it can instantly go to the desired speed,or ramp up to it slowly
it helps with arc starting initially,but not really essential.if youre welding in the upper power range with lots of wire speed, a slight creep in wire can be helpful to help you start the weld pool with a bit more control

 

[James Paul]

Thanks for explaining.
The welder’s still on the bench. It was a bit rusty in places, so i’am cleaning and spraying new paint on here and there.