Aerogarden Ultra LED blinking or strobing grow lights repair

[CapLeaker]

Have an Aerogarden Ultra here. All growing light LED's in the panel are blinking.
It started with an occasional blink here and there, but a day later it was strobing like crazy.

First off there is a 120V AC going through that little wire to that LED panel! Take it apart and there is a little PSU hidden in there. Three Chmec? 25V 1500uF caps looking pregnant and their guts out. Going to do a full recap with Panasonic FR and that should take care of that.

[stj]

i would be tempted to relocate the psu to the outside.

[CapLeaker]

Having the heat sink over the caps like that, will cook 'em good and they don't like that. I hate it when the caps are under a heat sink like that, as it always spells trouble.

[budm]

"First off there is a 120V AC going through that little wire to that LED panel! " That is due to the little blue disk cap between Hot and Cold side.

[CapLeaker]

budm, the input of that PSU has 120VAC, which comes from the base of the unit. It has nothing to do with that cap. Basically there are 2 boards, one in the base and that one inside the LED panel.
When I measured the 120V, the LED panel with the PSU inside was unplugged.

[budm]

What I am saying is that if you measure AC V between earth GND and ether one of the cold side red or white wire, you will see AC (the current should be very low), and I have have seen that safety cap failed badly even though they are supposed to fail open circuit.

[CapLeaker]

Yeah, I know what you mean now. Yes, I've seen these fail too.

[CapLeaker]

Got the caps, put 'em in ... aaaand? It works perfectly fine!

[dfbills]

Hey CapLeaker,

I'm seeing the same issue with a different board revision from the same year. I don't have those large caps like on yours. Not sure how to find the guilty caps.

I removed one of the heatsinks and took a bunch of pictures. I would appreciate any help you could provide to target the culprit.


Dave

[R_J]

Your problem is likely CD1, but there are only 3 caps so just replace all of them.

[CapLeaker]

I agree with RJ.

[redwire]

The SMPS has no feedback, so I'm not sure how it regulates the LED power? The caps look like polymer types for longer life.

I would suspect an LED going open-circuit which can make them blink and cut out. The LED's die glue or bonding wire will make an LED oscillate due to heating and cooling making the connection. But I'm not sure how many LED's at 30W this thing has or if there are resistors etc.

[dfbills]

Hey redwire-

In looking at the light board, I count 304 LEDs and 11 resistors (photos attached). They're permanently bonded to the aluminum board for cooling and stability with what looks like epoxy.

I'm still interested in troubleshooting this and admittedly a complete novice. What would you suggest for next steps? I have various voltmeters, but no oscilloscope available.

(I have not replaced the three polymer caps as I don't know how the three numbers on the top translate into something I can order online.)

[stj]

first line is the series,
second is the capacitance,
3rd is the voltage

[redwire]

Wow that's a lot of LED's. It looks like 8S white, and others are 3S red or blue+6S white. Some LED's look multi-chip so I could be wrong. I was trying to guess the PSU output voltage.

I would pull and test the three polymer capacitors, or just outright replace them. SMPS IC power cap CD1 is 10uF 50V likely failed. Two output capacitors CD2, CD3 are 470uF 35V and there is room for fatter parts which is what I'd put in for longer life, whatever fits even to 1,000uF+ each. "535Z" series I can't find data on.
Consider adding silicone thermal grease to the two heatsinked parts for better heat transfer.

[dfbills]

Thanks, stg. I can't find either exact series, but these values are available from a variety of manufactures. Am I correct to assume the capacitance is measured in micro-Farads?

10 μF
50 VDC

470 μF
35 VDC

Looks like I can get Kemet Aluminum Organic Polymer replacements for $0.64.

[stj]

that's correct - make sure the diameter or pitch between the leads matches or the replacements wont fit

[CapLeaker]

mine had three 1500uF caps! put some larger value than the 470uF in.There is enough space in yours.

[dfbills]

Thanks all. I've ordered my replacements. Will post back after my successful install.

[dfbills]

I had a very successful repair and the lighting array has been working flawlessly for a week now. A sincere thanks to all that pitched in to help me out.