Burnt Out LED PAR MOLEX Connectors

[partyanimallighting]

Hi all, I'm just seeking some advice/feedback concerning burnouts I'm encountering on some RGBWA+UV LED PAR's. The burnouts are severe to say the least and all are occurring at the two positive pins on the motherboard that feeds the diode plate via 8 wires (+,+,R,G,B,W,Y,UV) as these two wires handle the entire load for the 6 individual colors. I believe the actual harness wire is the fault as the gauge is pretty thin (seems to be around 26~28AWG) so I'm thinking that the current draw is too much, the wire heats up and burns the Molex connector, the actual wires themselves and the two positive pins. I've cut off a few centimeters of the positive wires and patched in 22 AWG wire and replaced the burnt out Molex connector on the motherboard and I'm hoping this will work. Oh! And yes, they're cheap Chinese outdoor rated PAR's. Any feedback or a better solution thrown my way will be greatly appreciated.

 

[DrV]

The issue is less likely the wire gauge and more likely the spring contacts in the female part of the connector. If you look at the wire you'll see that it has only overheated right at the end. If you have room inside the fixture I would solder some wires directly onto the PCB and splice a better quality connector pair into that cable. 

[Tomo]

Usual causes of this kind of failure are bad crimping, undersized/low quality connector and undersized wire.
Undersized wire is a leading cause of bad crimping, of course.

If the issue really is that the wire is undersized for the load & conditions, then it'll eventually burn out further up or at the other end.

I'd recommend replacing the whole run, don't just patch in across the failed bit.

Also, the greenish tint likely indicates moisture, so have a look for signs of corrosion elsewhere before closing everything up.

[musht]

Is that an unused V+ pad beside connector?

Wiring probably CCA with 18AWG insulation....22AWG conductor.

Replace with copper at decent guage direct to PCB with XT60 connector pair in middle.

Wipe of silicone grease on mating parts of connectors and around seals does help.

 

 

[adam2]

15 hours ago, Tomo said:

Usual causes of this kind of failure are bad crimping, undersized/low quality connector and undersized wire.
Undersized wire is a leading cause of bad crimping, of course.

If the issue really is that the wire is undersized for the load & conditions, then it'll eventually burn out further up or at the other end.

I'd recommend replacing the whole run, don't just patch in across the failed bit.

Also, the greenish tint likely indicates moisture, so have a look for signs of corrosion elsewhere before closing everything up.

The observed greenish tint could be due to chlorine or chlorine containing compounds, released due to overheating of PVC insulation.

[partyanimallighting]

Hey guys, thanks for all the responses!

Tomo, I believe it's a combination of everything mentioned. Cheap workmanship, cheap materials, undersized wire for the load, the heat factor as these are outdoor rated thus only convection cooling and the moisture factor from heating up and internal condensation.

musht, changing out the entire harness with a better AWG is one solution but soldering directly to the PCB isn't possible without a connector like the XT60 you recommended midways in the harness assembly so that the diode plate assembly can be disconnected and removed. Something like a 8 pin DT connector in a suitable AWG would be great.

adam2, I would suspect damp silica gel but I couldn't find any packs inside these units. Maybe they dissolved a while back.

Overall, they're just poorly designed units meant for the cheap side of the market. I believe these and dozens of similar models are available for around USD60.00 ~ USD100.00 per unit anywhere on AliBaba. I have a similar unit, smaller build, MUCH BETTER quality, from Longman Lighting and this particular model has served me so well since I first bought them 10 plus years ago. I might have changed maybe a couple constant current amperage PCB's and power supplies in these units over the past 10 years. Practically bulletproof.

I really appreciate all the feedback to add to my knowledge base.

 

[musht]

Thinking just replacing the V+ supply lines, XT60 2 pole, MT60 3 pole , popular RC connectors easy to find.Anderson Powerpole with 15A contacts , easily solderable, 1 to many poles.

Silicone grease 

http://www.satcure.co.uk/tech/silicone.htm

[partyanimallighting]

Soldering directly to the motherboard isn't an option but I'm thinking the the burnouts occur on the two +ive pins so I can always patch in a heavier gauge of wire with a two pin disconnect and simply cut the existing Molex connector, reducing it to 6 pins down from 8 pins. That way, I can disconnect the 2 pin +ive connection and the Molex and have the disconnectivity I need. Something like this connector that's used on the existing motherboard for the 24VDC input.