Mighty Mini Repair

[macebobo]

Hi all, my search foo is not working tonight (read about 20 threads related to MM, but not repairing them) as I cannot find the thread that showed how to troubleshoot failed LEDs in the MM flood lights. All of my whites failed this year, but I know it must just be one or two and for the life of me I cannot figure out how to diagnose these puppies. If someone with good search foo would be so kind to post a link to the thread, I will add two internets to your account.

Thanks,
John

[budude]

There are a couple ways - one is to use an ohmmeter and measure the resistance in both directions of each LED - it should be very low in one direction and very high in the other direction. LEDs typically open so bad ones will typically be high (actually infinite) in both directions. Another way is to use a button cell and affix wires to both sides (a small clamp or clothespin works - but typically you can't solder them easily) and walk through each LED trying the cell in both directions. You can can compare measurements or battery placement based on the working set of LEDs.

These are no fun to replace - take your time. If you can heat both pins at the same time and have someone pull on the LED from the front side (but ONLY when the solder is completely melted on both pads!) they come out easily and the pads can be cleaned up.

[folksy]

This may not be the correct way or scientific way but it has worked for me in the past.

If I am having problems with a particular color I light up that color using my ren24lv then I take a new LED and touch the leads on the back side of the board to each soldered LED. When the light string lights up I know which one is bad.

Hope it helps.

Jason

[jklingert]

If you installed the LM317 constant current source instead of the resistors, you can power up the flood and then short across the leads for each led one at a time in the bad column until the rest of the column lights up. When it does, you have the bad led. Remember that each color has two columns of leds on separate circuits.

You can also use a rubber band attached to the body of the led to pull it from the board when you heat the two leads up.

[mikeh65]

I go simple, I just use a battery holder, which holds two batteries, and just touch the negative lead to the square tabs and the positive lead to the round tabs. I touch it to each pair to the led terminals to power up the led. If it does not light, it's the bad one.

[BillAd]

I just connect the flood to the controller and take a piece of wire and briefly short one led at a time till I find the one that is bad.

[macebobo]

Thank you everyone. I have found the 8 bad LEDs (on 4 MM) and will be working on fixing them today. My meter provides enough voltage to dimly light good LEDs. Now to find a rubber band to extract the bad ones

-- John

[Greg in Canby]

I have messed up the pads on the top of the board doing this, use caution.

[mikeh65]

I have also had issues with the white on the MM. I have updated all of my floods to include a 110 ohm resister on the white channels instead of the 56 ohm that is listed. I replaced the resistors on two of my MM during show operations and had no further issues with them. While repairing the other MM over this weekend, I replaced the rest of the resistors. Just a suggestion.

[macebobo]

I will be making all of my white channels on my current MM constant current. Any new builds will have all channels constant current. Thanks again for all of the advice, cautions and encouragement. -- John