Express Self Test - LED's Shimmer

[Dholley]

Dear DLA Members,

I hope you can help me identify the problem. When I run the self test on my Express it runs through all of the test and the LEDs come on as expected but they shimmer. On occasion they will go out all together. If I push on the heat sink the led lights will  come back on. I have double checked my solder joints and they apprear to be okay, but is this still an indication of a bad solder joints).

Thank you,

Danny

[Dennis Cherry]

Dear DLA Members,

I hope you can help me identify the problem. When I run the self test on my Express it runs through all of the test and the LEDs come on as expected but they shimmer. On occasion they will go out all together. If I push on the heat sink the led lights will  come back on. I have double checked my solder joints and they apprear to be okay, but is this still an indication of a bad solder joints).

Thank you,

Danny

How many channels do you have LED light strings for this test?

If only one did you move the lights to another channel and check again?

Are the LED lights Full or Half wave?

[Dholley]

When I speak of the LEDs I am speaking of the LEDs on the Express. The little green LEDs, channels 1 through 16. I am testing all 16 channels via vixen

[Dennis Cherry]

When I speak of the LEDs I am speaking of the LEDs on the Express. The little green LEDs, channels 1 through 16. I am testing all 16 channels via vixen

Sorry, mis-understood your post.

You might check that the capacitor next to the right readout and the large chip is soldered well. Sometimes the coating on the capacitor will wick down the leads and prevent it from soldering to the pads.

[rm357]

I assume you mean the individual channel leds and not the numeric leds.

For the channel leds to shimmer is unusual - I'd try re-flashing the pic before doing anything else. If that doesn't fix it, then you need to post pictures of both sides of the circuit board - especially around the power supply.

The pic output goes through the channel LED and the opto-isolator. If the opto-isolators are installed correctly, the problem goes back to either the pic or the power supply. The triacs attached to the heatsink are connected to the output of the opto-isolator which is there to separate the digital level signals from the AC mains power.

The other things that I can think of that might cause this behavior would at a minumum make something very hot, blow the fuse, or let out some of the magic smoke that all electronics require to operate properly. Let it shimmer for a few seconds, then UNPLUG, UNPLUG, UNPLUG the board and feel the triacs to see if any of them are hot.

Yeah, I said unplug three times with the equivalent of an e-mail shout. If you leave it plugged in, it can bite, hurt, or even kill you, so please unplug it before feeling components with your fingers. There are many places on the board that are connected directly to the hot leg of the AC outlet.

RM