Auto-darkening welding mask - got wet

[mab2]

Hi,

As the title says my autodarkening welding mask got wet and no longer works. I don't know how long it was wet for (hours - couple of days).

I've tried to dry it out and when it still didn't work I opened it up to help any residual moisture dry out but it seems dry, and the two lithium cells (CR2430) are still showing 2.94v and 3.02v. NB there's also a solar panel under the circuitboard and cells.

This is a long shot perhaps - but any suggestions as to how diagnose it's problems? - how to get it working ? - maybe some WD40 in the switches? - or do I just have to buy a new one?



thanks
m

 

[DerStrom8]

The first thing I would do is check the batteries and contacts for corrosion. A quick, gentle clean with a fine wire brush might clean off any corrosion. For that matter, I would check for corrosion on other parts of the board as well. It could be that one of the chips has been shorted out and destroyed, in which case a repair would be very difficult. I guess if there's no corrosion or you clean it off and it still doesn't work, you may just have to bite the bullet and get a new one.

Good luck, hope you can get it fixed!

Regards,
Matt

 

[mab2]

Hi Matt,

there was a little dry white deposit on one lithium cell and one corner of the circuit board which I carefully removed with the wooden end of a matchstick - there seems to be little actual corrosion and the battery voltage is present on the circuitboard.

I was hoping that as the batteries are still showing a good voltage that nothing had been shorted to the point of destruction - but it still doesn't work.

for info: the 'wet' was heavy condensation under the roof of the workshop which dripped off the beam into the mask, so it would've been fairly pure water - at least before it soaked through the wooden beam.

A new one isn't terribly expensive but I just hate to throw it out without trying to fix it first - it's such a waste.

thanks
m

 

[JimB]

Try srcubbing both sides of the PCB using Iso Propyl Alcohol and a medium soft brush.
Try cleaning the switches, operate them several times, having given them s squire of switch cleaner (not WD40).

JimB

 

[KeepItSimpleStupid]

The LCD doesn't like water.

 

[mab2]

thanks for the replies - I wonder where to get IPA now... trouble is, by the time i've bought IPA & switch cleaner I'm half way to the cost of a new mask.

The LCD doesn't like water.

umm.. I'm not sure the water got into the LCD - as far as I could tell it was just one lithium cell and a portion of the pcb - would there be any visual signs of water damage to the LCD if it had? (other than it not working of course).

I wonder if I applied a couple of volts to the lcd wires for a moment if that would verify it's function without frying the driver cct?

 

[mab2]

Fixed!

thought i'd trace the power from the lithium cells to see if there might be some kind of fuse or something to cut out when shorted- didn't find any such thing but I did discover that the pcb feedthroughs on the B+ seemed to be open circuit - hence the voltage difference between the two cells, and there was no supply to one of the ic's (HCF4052 - bottom right in the pics).

soldered in a couple of patch wires and hey presto - it works.

I'm guessing that the feedthroughs are not coated in the green lacquer and so more susceptible to corrosion? (and maybe some galvanic effect of B+?) - dunno, but it's working now and that's what matters.

thanks for the suggestions folks - sometimes just having other peoples thoughts, ideas & opinions is enough to keep you from giving up on an impossible-seeming task.

 

[KeepItSimpleStupid]

Nice work!