HLG B drivers not dimming down to 10%

1

1212ham

Well-Known Member
kushedy said:
Not looking to dim a driver to 0%. Never was.


Simple point: I have lots of HLG drivers. Not unhappy with them. None dim to 10% which I was under the impression they were meant to. I started this post to help with troubleshooting.


As pointed out in the very first post I suspect the use of cheap potentiometers to be the cause. Rather than spending time re-wiring potentiometers I thought I'd throw it out on RIU & see what other people’s experiences were with potentiometers.


Sounds like the answer for full accurate dimming is pwm dimming. From what I have read that generally involves expensive controllers.
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So how low do they dim? Try shorting the dim wires to take the pot out of the equation.
 
CannaBruh

CannaBruh

Well-Known Member
1212ham said:
You need a minimum of 100k for full power, not 90k.
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Right, that's why i don't see why 10k solves this for "full on" if your pot is on the low end of a 20% tolerance it gets you closer but maybe there's more i don't understand. I was initially under the impression that the 10k was there to bleed some current preventing a dead short across the dim terminals but maybe not.
 
C

conversekidz

Well-Known Member
kushedy said:
Not looking to dim a driver to 0%. Never was.


Simple point: I have lots of HLG drivers. Not unhappy with them. None dim to 10% which I was under the impression they were meant to. I started this post to help with troubleshooting.


As pointed out in the very first post I suspect the use of cheap potentiometers to be the cause. Rather than spending time re-wiring potentiometers I thought I'd throw it out on RIU & see what other people’s experiences were with potentiometers.


Sounds like the answer for full accurate dimming is pwm dimming. From what I have read that generally involves expensive controllers.
Click to expand...
Arduino's are cheap....

https://www.arduino.cc/en/Tutorial/PWMhttps://www.arduino.cc/en/Tutorial/PWM
 
nfhiggs

nfhiggs

Well-Known Member
CannaBruh said:
That is interesting design approach but maybe I don't understand why it's needed then?
100k pot at 20% (80k worst case) + 10k resistor = 90k
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You need 100K or more to get full power from the driver. Less than 100K you're not getting full power. Most people look for 10% tolerance pots.
 
K

kushedy

Well-Known Member
I put a 10k resistir in as I had heard that cheap potentiometers had a habit of shorting out completley when switched down to the lowest setting. The 10k resistor is meant (from my uderstanding) to keep the lights on at 10% should the potentiometer die.
 
K

knight mare

Well-Known Member
The way I see it is if you are having to add 10k resistor then you are adding it across the range so instead of dimming to 10% you will dim down to 20% at full dim as you have added 10%
the only way I can see to get the adjustment is to reject any pot that doe's not meet spec
 
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ANC

ANC

Well-Known Member
CannaBruh said:
That is interesting design approach but maybe I don't understand why it's needed then?
100k pot at 20% (80k worst case) + 10k resistor = 90k
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Most people would probably buy +/-10% pots... so anything from 90 to 110k
 
CobKits

CobKits

Well-Known Member
kushedy said:
I put a 10k resistir in as I had heard that cheap potentiometers had a habit of shorting out completley when switched down to the lowest setting. The 10k resistor is meant (from my uderstanding) to keep the lights on at 10% should the potentiometer die.
Click to expand...
no its only purpose is to make sure resistance is AT LEAST 100K where pots can be +/- 10%. so if you have a pot thats really 90K it becomes 100K when you add the resistor

and if your pot is 110K making it 120K doesnt hurt anything it just changes the range of your dimming very slightly

hardly anybody runs lights below 20% as they are not as efficient
 
Rahz

Rahz

Well-Known Member
knight mare said:
The way I see it is if you are having to add 10k resistor then you are adding it across the range so instead of dimming to 10% you will dim down to 20% at full dim as you have added 10%
Click to expand...
Bingo. HLG if I remember correctly dims to 10% so if you're adding a 10K ohm resistor instead of 10-100% you get 20-110%.
 
K

kushedy

Well-Known Member
From memory I picked up thee 10k resistor thing from the Growmau video quite a while ago & have been doing it as standard ever since. Makes sense what you guys are saying. I am going to be wiring up another one shortly so will leave out the resistor & see what readings I get. Thanks for all the help
 
CannaBruh

CannaBruh

Well-Known Member
PurpleBuz said:
Somebody very smart recommends using a 10k resister to avoid dimming to 0%.
https://www.rollitup.org/t/meanwell-led-drivers-3-in-1-dimming-function.838760/

imho if you want it dimmed below 40% may as well just turn the light off.
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This is exactly my assumption originally, 10k would prevent a dead short across dim terminals when pot wiper swings to 0r position which might spell failure for the driver if you were to short the dim terminals, but maybe it can work that way?

Agreed, if you want to dim at all use more drivers and wire them up for quick connections, easy to change in and out and they can be found all day on ebay for next to nothing just make sure you check polarity and that the voltages are what they claim, i've found some that were off on both.

Most cheap pots are not going to be 10% though, even if they say they are. Even nice alphas are going to be 20% often, exceptions can be found.

My original reply for context:
That 10k resistor is there to present a minimum 10k Ohms for when your pot is turned to 0Ohms? Removing that presents a dead short between dimming pins with pot turned to 0Ohm position (might be no good)
Click to expand...
 
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