Led cornlight? Repair question - Page 1
Forum section: electronics / repair

author: bratboy
author_rank: Newbie
timestamp: April 09, 2021, 09:11:50 pm
content: Hi there, I have a question about a corn light I have. I picked it up and opened it and there was a 22 microfarad capacitor that blew up. I'm thinking that's the only thing I need to repair. It's an epoxy. Anybody have any advice on how I can get in there and replace it? I'm not an expert Electronics guy, I'm very basic but I've done repairs in the past.

author: shakalnokturn
author_rank: Super Contributor
timestamp: April 09, 2021, 10:02:34 pm
content: Scratch away if you can, you need to remove enough grey stuff, then find the right polarity.If you're not used to electronics though I'd consider this a hazardous waste of time.I'm used to electronics and don't bother repairing single "bulb" assemblies...

author: bratboy
author_rank: Newbie
timestamp: April 10, 2021, 06:53:22 pm
content: Hazardous in what way? It did have a polarized capacitor but I understand you can replace it with a non polarized. Is that right? The thing knocks out a lot of light so I might as well try to make a repair.https://www.amazon.ca/Equivalent-Replacement-Warehouse-Driveway-Basketball/dp/B071R6YYYM?ref_=d6k_applink_bb_marketplace

author: BrokenYugo
author_rank: Super Contributor
timestamp: April 10, 2021, 11:23:48 pm
content: Hazardous because it's partly or entirely mains referenced. A waste of time because with a failure that violent I'd expect that's a symptom of another, potted, problem.If this is a ESR sensitive position (again, potting in the way to reverse engineer) a NP cap may not survive.

author: amyk
author_rank: Super Contributor
timestamp: April 11, 2021, 02:01:09 am
content: 22uF sounds like the main reservoir cap, probably rated 400V. The fact that it exploded suggests you might want o see what caused that first, or the replacement may do the same.I've not heard of the term "cornlight" before - I guess this is "COB on the corn"...?

author: bratboy
author_rank: Newbie
timestamp: April 13, 2021, 02:26:24 pm
content: It's a 50v and yeah cob on a corn sounds right!

author: Syntax Error
author_rank: Frequent Contributor
timestamp: April 13, 2021, 02:55:14 pm
content: The cap could have failed due to poor design, cheap manufacturing, heat stress, over voltage, water ingress or a lightning strike. It's anyone's guess, but LED bulb failures are often less catastrophic than this.The LEDs may have failed too. Test the strips with a diode meter or low voltage DC source.Seriously, trash the mains PSU part and keep the LED arrays as they might be usefull for some other project using a safe and proven DC supply.

author: amyk
author_rank: Super Contributor
timestamp: April 14, 2021, 01:11:58 am
content: 50v is not the mains reservoir cap, but probably output smoothing, in which case the cause of failure is likely the LED string went open-circuit, causing the constant-current driver to raise its output voltage to the max and exceeded the 50v.

author: james_s
author_rank: Super Contributor
timestamp: April 14, 2021, 04:07:45 am
content: If it wasn't potted I'd say it's a reasonably easy repair, but potted adds a huge amount of labor and difficulty. If I really wanted to salvage something I think I'd cut off the existing driver and wire the LED part to a different driver.