aquarite SWG trouble desoldering varistor from mother board.

nsxsurgeon

New member
Aug 4, 2014
4
Stamford
I have Aquarite SWG and like many other owners the varistor(black little component) burned out. My unit is just over a year old and warranty is for parts but not labor--I called Hayward and said I need to call one of their contracted people, even though I can see the varistor is burned out and cracked. I already ordered the $3 part from digi key. The problem is that I am having trouble desoldering it in order to put the new one on. I even bought a 45 watt desoldering gun but it seems that there is some protective coating over the solder joint which keeps me from heating up the solder to melt. Any suggestions would be appreciated. I bought a new mother board on line from amazon in the meantime and everything is working ok but I would like to at least have a back up motherboard now.
 

JohnT

Admin
Mod Squad
TFP Expert
Apr 4, 2007
9,723
SW Indiana
Sometimes the easiest way is to add solder to the tip of the iron and let it flow onto the old solder. The molten solder conducts heat very well. Then use either solder wick or use the heat and fling method to get the solder off the board.
 

nsxsurgeon

New member
Aug 4, 2014
4
Stamford
thanks for your reply,unfortunately I have tried that without success. It seems like the soldering joint has been covered by a metal foil which looks like some heat protecting foil. there is this rectangular area of metal foil on both sides of the motherboard where the leg of the varistor goes through. this foil over the solder joint does not melt. It almost looks like it was deliberately put there to prevent someone from desoldering it. I am not an expert i desoldering but I thought the 45 watt desoldering gun should be able to melt the solder easily. the leg of the varistor looks like it is made of copper but it almost looks like the foil on the component part of the motherboard extends on the legs of the varistor about one to two millimeters. not sure what else to do.
 

nsxsurgeon

New member
Aug 4, 2014
4
Stamford
it looks like the old leads are made of copper but the new varistor looks like steel/iron--(silver colored). Is it ok to solder two different metals together? Sounds like your suggestion is a good one as the existing leads are about 1.5 cm long. Thanks
 

JohnT

Admin
Mod Squad
TFP Expert
Apr 4, 2007
9,723
SW Indiana
it looks like the old leads are made of copper but the new varistor looks like steel/iron--(silver colored). Is it ok to solder two different metals together? Sounds like your suggestion is a good one as the existing leads are about 1.5 cm long. Thanks
Possibly tinned, but either way you can solder them together.
 

Bama Rambler

Mod Squad
TFP Expert
Bronze Supporter
LifeTime Supporter
Jun 22, 2009
23,874
SouthWest Alabama
Just as a note. A 45 watt soldering iron is going to take a long time to get hot and it's not going to be very fast at transferring the heat to the part needing to be desoldered.

I'd like to see a picture of the "protective foil" you're talking about.
Also, how old is the unit?
 

Bama Rambler

Mod Squad
TFP Expert
Bronze Supporter
LifeTime Supporter
Jun 22, 2009
23,874
SouthWest Alabama
Those large metal lands are a sort of heat sink, but the current limiter is just soldered into them they're not actually covering the leads.

The fact that the lands act like a heat sink is why your soldering iron had a hard time melting the solder. Basically you need more heat and it needs to be concentrated right where the leg dimples on the lands are.
 

jlentz32

Well-known member
May 27, 2011
61
What Bama said, that's a huge heat sink. You'll need to crank the heat up on the soldering iron and keep adding solder to get the joint to flow.

Id clip the leads on the part first. Then use a needle nose to pull the leads out as you hear it up. Clean it up with a desoldering tool or braid after you get the leads out.
 

jlentz32

Well-known member
May 27, 2011
61
To clarify. By keep adding solder I mean you'll probably use about 6 or more inches, the molten solder will help conduct the heat better.


One more thing is that since this is most likely ROHS (lead free) the melting point on the solder already on the board is higher than the 60/40 you've probably already got.

It will take some patience but it's doable.