Help me repair my cob light please

Tim Fox

Tim Fox

Well-Known Member
Help, I have a cob panel with four cobIMG_20240913_163646638.jpgs wired in series with the driver shown in the pic, this light has been a work horse for me year after year anyhow one day it just went dark, I have power to the panel, I've tested that with my volt meter, my question is how do I test this driver? Do I set my volt meter on DC 238 volts and test across the positive and negative on the driver? If it's a cob that's burned out is there a way to test that with my meter? Maybe set on ohms resistance? Anything else I should check for? Thanks much
 
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1212ham

Well-Known Member
Yes, test voltage across positive and negative leads from the driver. If there is no DC power, check to be certain there is AC power to the driver.

A dead cob can be found with a jumper wire across one cob at time, when you get to the dead cob the jumper will complete the circuit and other three will light up.
 
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1212ham

Well-Known Member
Tim Fox said:
That makes good sense thanks, I'm guessing the momentary increase in voltage across the three remaining cobs won't hurt them if it's brief?
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There won't be a voltage increase. What you have is a 1.05 amp constant current driver, it regulates the voltage from 119v to 238v to maintain a 1.05A current through the series string of cobs.
 

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Tim Fox

Tim Fox

Well-Known Member
1212ham said:
There won't be a voltage increase. What you have is a 1.05 amp constant current driver, it regulates the voltage from 119v to 238v to maintain a 1.05A current through the series string of cobs.
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I'm guessing there is a limit to how many cobs this driver can power? Are you saying this driver can power one cob and stay at correct amp and voltage, and power say 6 cobs and still stay correct amp and voltage, thanks
 
1

1212ham

Well-Known Member
Tim Fox said:
I'm guessing there is a limit to how many cobs this driver can power? Are you saying this driver can power one cob and stay at correct amp and voltage, and power say 6 cobs and still stay correct amp and voltage, thanks
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There are limits, the combined voltage of the cobs needs to be within the drivers 119v-238v operating range or it's not going to work.

I'm guessing your cobs are around 54-56v at rated current. Four 55v cobs is 220v and 220v x 1.05 amps is 231 watts, a good match to your 240 watt driver.
 
Tim Fox

Tim Fox

Well-Known Member
1212ham said:
There are limits, the combined voltage of the cobs needs to be within the drivers 119v-238v operating range or it's not going to work.

I'm guessing your cobs are around 54-56v at rated current. Four 55v cobs is 220v and 220v x 1.05 amps is 231 watts, a good match to your 240 watt driver.
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Thank you yes , alright I'll get to diagnosing the panel and report back
 
Tim Fox

Tim Fox

Well-Known Member
1212ham said:
Yes, test voltage across positive and negative leads from the driver. If there is no DC power, check to be certain there is AC power to the driver.

A dead cob can be found with a jumper wire across one cob at time, when you get to the dead cob the jumper will complete the circuit and other three will light up.
Click to expand...
I got around to testing my driver , I also tested a known good driver (different size) and sure enough no voltage on the dc side , so i ordered a new driver from mouser electronics, con kits didn't have them listed on his website, I'll update later when it arrives, indoor season is upon us,
 
Rocket Soul

Rocket Soul

Well-Known Member
Tim Fox said:
I got around to testing my driver , I also tested a known good driver (different size) and sure enough no voltage on the dc side , so i ordered a new driver from mouser electronics, con kits didn't have them listed on his website, I'll update later when it arrives, indoor season is upon us,
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Congrats on fixing up your old light. Id like to point out a take away for the bulb enthusiast loving the idea of changing bulbs all the time: Leds will outlast even their powersource. Imagine you could still use the same bulb even after your ballast gave up the ghost?
Though no shade on any grower just grow with what you like.
 
Tim Fox

Tim Fox

Well-Known Member
The new driver arrived today and I bench tested the driver and sure enough 238 volts , so the old driver is indeed dead, ok now to wire it up, I found clones at the local state legal dispensary for $15 dollars, I need to hustle hahaIMG_20241004_153255692.jpg
 
Isawthelight

Isawthelight

Well-Known Member
1212ham said:
Yes, test voltage across positive and negative leads from the driver. If there is no DC power, check to be certain there is AC power to the driver.

A dead cob can be found with a jumper wire across one cob at time, when you get to the dead cob the jumper will complete the circuit and other three will light up.
Click to expand...
Late reply...For those with a volt-ohm-meter: These LEDs are wired in series. If the driver output powers up and only one of the LEDs are bad (opened - not shorted), the voltage across a single bad LED would be the same as the driver's output voltage. (voltage is felt across an open circuit - basic electrical troubleshooting tip).
 
Tim Fox

Tim Fox

Well-Known Member
Rocket Soul said:
Awesome. How long have you ran this light? I seem to remember it since i was a fresh noob here :) have you ever replaced the cobs?
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Good question, I was trying to come up with an age since I don't keep records, Oregon went rec legal 10 years ago that's when I started growing again, I did a couple of grows with some cree cxa3070 cobs and I still have those , I should hook them up as a backup light, but they don't have dimmers , just switches for turning individual cobs on and off, anyhow, I would say this light lasted 9 years and through one or two grows per year, I was surprised it died i sotta thought this light would outlive me, maybe it will with a few repairs, I'm going to put a piece of scratch paper with the diagnostics written on it Incase it fails again and I need to make more repairs down the road, I think I found some clones , good indoor weather is just about here in Oregon, good to see you on here still
 
Rocket Soul

Rocket Soul

Well-Known Member
Tim Fox said:
Good question, I was trying to come up with an age since I don't keep records, Oregon went rec legal 10 years ago that's when I started growing again, I did a couple of grows with some cree cxa3070 cobs and I still have those , I should hook them up as a backup light, but they don't have dimmers , just switches for turning individual cobs on and off, anyhow, I would say this light lasted 9 years and through one or two grows per year, I was surprised it died i sotta thought this light would outlive me, maybe it will with a few repairs, I'm going to put a piece of scratch paper with the diagnostics written on it Incase it fails again and I need to make more repairs down the road, I think I found some clones , good indoor weather is just about here in Oregon, good to see you on here still
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I couldnt get of riu if i wanted to, but a
Nowadays more on other forums aswell:) good to know youre getting a grow together.

Hopefully setting up production of my own diy gear around xmas. When you get tired of people not getting gear right i guess you just have to do it yourself :lol:
Efficiency seems like a dead horse, better to make things that can give you better crop quality. In the end 30-40w is not a big deal for most growers if they can dramatically change what their cuts do, in the grow, nose and head. Been waiting for someone to go the extra mile on exotic diodes that one would expect someone to try something with and take to market; having "done my own research" (not MTG style, lol) i feel ready to get on with it now.
 
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