1.2" 8x8 I2C backpack repair?

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mkruse123
 
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1.2" 8x8 I2C backpack repair?

Post by mkruse123 »

I hooked up 11.1V off the wrong side of my breadboard bus (oops) and had 5 LED 8x8 1.2" I2C backpacks parallel wire and operational at the time. (I was attempting to go from my breadboard setup to my LIPO battery arrangement w/5V BEC, and mixed up my wires)

All lights went dead, and after separating them all from each other and testing them one by one, I have found that there is 1 left that still functions correctly when hooked to the 5V, Ground, Clk, and Data.

I am not an EE, so that is the limit of my knowledge of what to check. Is there something that I can do to repair these, or just buy new ($50) since it's too hard to diagnose?

Thanks

Mark

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Re: 1.2" 8x8 I2C backpack repair?

Post by adafruit_support_bill »

There are two voltage sensitive components to be concerned with. Each has different characteristics. The chip on the backpack will be less tolerant of swignificant over-voltages. If a backpack is not working, you can probably assume that the chip is dead. The LEDs in the matrix can usually handle an overvoltage condition - if it is brief enough. You might be able to salvage some of the led matrices.

Of course there are 64 leds in a matrix and it is possible that some survived and some did not. The only way to find that out for sure is to remove them from the dead backpacks and test them. Removing multi-pin devices without specialized desoldering equipment is not an easy task. If you have a hot-air-gun, you can try heating the back of the board with that until the solder melts (since the boards are dead, you don't have to worry so much about damaging them.)

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mkruse123
 
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Re: 1.2" 8x8 I2C backpack repair?

Post by mkruse123 »

I own a Hako vacuum desolder gun (since I made the mistake of soldering the 1.2" LED backwards... (twice) before i figuered out that they were direction sensitive {I was reading the .8" directions which were NOT direction sensitive}). It makes short work of removing solder from pins and fixing mistakes quickly (best tool I ever bought). I can remove the LED's from the backpacks and put them on the "good" backpack and retest the matrices. Supposing I diagnose the LED's OK, can I get the chip and/or the backpack purchased separatedly and replace them?

I can solder/desolder well, I have a multimeter to test between points to check whatever needs to be checked, but I just need to know where they go and what to purchase...

Thanks

Mark

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Re: 1.2" 8x8 I2C backpack repair?

Post by adafruit_support_bill »

I own a Hako vacuum desolder gun (since I made the mistake of soldering the 1.2" LED backwards.
Awsome! Then you are well equipped to do this.

We do not sell the chips separately. But they should be available from most of the major suppliers (Mouser DigiKey etc). The part# and specs are here: http://www.adafruit.com/datasheets/ht16K33v110.pdf

If you have one backpack that is capable of lighting all 64 pixels in a matrix, then you can use that as a tester (it is possible that one or more row or column drivers in the multiplexer might be bad, so don't give up on a matrix until you are sure the backpack is 100% operational)

If you cant identify a 100% good driver chip, you'll need to test the leds 1 by 1. You can do this with a resistor (1K should do) and a couple of jumper wires. For each row, connect the row pin to ground via the resistor. Then for each column, connect the column pin to 5v and see of the corresponding led lights.
Pinouts are in the data sheet here: http://www.adafruit.com/datasheets/BL-M12A881.PDF

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mkruse123
 
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Re: 1.2" 8x8 I2C backpack repair?

Post by mkruse123 »

Digikey and Mouser don't supply it. Holtek website doesn't list an authorized distributor in the US. Any other ideas?

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Re: 1.2" 8x8 I2C backpack repair?

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mkruse123
 
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Re: 1.2" 8x8 I2C backpack repair?

Post by mkruse123 »

It had a link the the data sheet and a price for an unrelated chip. The sponsored link to findchips.com didn't have a vendor either. :(

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Re: 1.2" 8x8 I2C backpack repair?

Post by adafruit_support_rick »

They simply may not be available to purchase. :(

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Re: 1.2" 8x8 I2C backpack repair?

Post by mkruse123 »

No way to buy from Adafruit?

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Re: 1.2" 8x8 I2C backpack repair?

Post by adafruit_support_rick »

Nope. Sorry. We don't sell those chips individually.

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