So I finally got my shruthi going! Just have a problem with the LEDs. LED 2 is at the correct brightness, but all others are dim. I’ve tried reheating the eight resistors but this hasn’t helped. Does anyone know why 1 led would be bright and the others not? Thanks
Should add that these are green LEDs. I’m building the standard sm4 filter version.
Have you mixed up the two 74 series chips?
The chips on the front of the control board? No, everything else seems to be working including filter board, lcd screen pots. Seems like not enough power is getting to 7 LEDs
Resistor network wrong way around ? Is the white dot at pin 1 ?
eelco: the resistor network is for the switches only.Bear00:
- check if the 8 LED resistors have the same value (check the color code)
- measure the voltage between GND and the side of the LED resistor which is connected to the 74HC595. Before each measurement make sure the LED is lit. There should be 5V.
Is that a kit or a self-sourced build? I remember that some bad 595s from Tayda caused this problem. Original post here
@cj55: ah yes, stupid me …
Ok all resistors are the same value. The voltage for LED 2 which is brighter than the others is around 2.09, the dim ones are around 1.80. Control board is from a kit, but sm4 is self sourced as i destroyed the one that came with the kit. Is it worth replacing the 595 then? Is that just IC3?
Yes, that’s IC3. Try replacing it. It might also have been damaged by a static discharge.
OK thanks will try that