mjr... I've hit another impasse with my flashers. I got the new ULN2064 chips in and have swapped the chips out. That is always a lot of fun, you'd think I'd learn and put sockets in but I forgot to order those again and on they went straight to the board.
I've isolated my 5V's so there is no chance of sending 12V into these chips again and I've swapped out all of my RGB LED's. The problem I'm running into now is that a couple of the lights aren't working. From JP11 R2 and G4 aren't lighting up for me. I have verified that the 5V's is getting to the + side of the RGB. I have verified continuity with my multimeter that the wire that goes to pin G4 is showing up on IC7. I've actually wired B4 up to negative side of the Green light on my RGB and it lights up so I know the LED is good. Is there any steps you could suggest for me to trace the pins from R2 and G4 on JP11 over to IC7 and IC5?
I know what you mean about unsoldering - it's a gigantic pain with these big chips with lots of pins. I know it's not any help for you after the fact, but for future builds, at least, I've added suitable sockets to the parts list for all of the big chips. I didn't use sockets in my own build either, but I'm starting to lean towards recommending them. It makes it so much easier to recover from this kind of problem, as well as things like inserting the chip wrong in the wrong orientation when soldering it.
Anyway... Am I correct that all of these outputs were working before that unfortunate 12V cross-wiring happened? If so, that should at least narrow the number of things to look at.
Tracing the circuits, if we start at 2R:
- JP11 pin 8 (2R) goes to IC5 pin 16
- IC5 pin 14 is the input side of that, connecting to OK1 pin 9
- OK1 pin 8 is the input side of *that*, connecting to IC1 pin 3
I'd check each pair of those for continuity, testing at the actual chip legs on the top of the board rather than the solder pads. The problem is sometimes a bad solder joint between the pin leg and solder pad that's practically impossible to detect by visual inspection. Testing continuity at the chip pins can usually catch these.
The equivalent for 4G:
- JP11 pin 5 (4G) goes to IC7 pin 9
- IC7 pin 11 goes to OK3 pin 11
- OK3 pin 6 goes to IC1 pin 10
If all of that checks out, you can try some powered-on tests. You can remove the KL25Z for these so that you can get to the chips more easily, if necessary.
The first test is to (very carefully!) attach a probe wire to +5V from the secondary PSU - you can use the +5V on JP11 for this. Then touch the other end of the wire to the Darlington inputs - IC5 pin 14 for 2R, IC7 pin 11 for 4G. If the respective LEDs light up, the Darlingtons are working. If not, the problem is probably that those stages of the Darlington chips are dead. Hopefully not the case given that you just replaced them!!! But defective chips from the factory can occasionally happen.
The second test is a little trickier because you need a resistor to add to your probe wire. About 1K should work. Attach the probe wire to the PSU2 ground. Attach the other end to one end of the resistor. Then attach a second probe wire to the other end of the resistor, and carefully touch the other end of that probe to the OKn input pins. For 2R, that's OK1 pin 8; for 4G, it's OK3 pin 6. This will test the optocoupler. Again, if the respective LEDs light up, the optos are good; if not, you might have a problem in the respective opto chips.
Hopefully you'll track it down with the continuity tests and won't have to go to all that extra trouble!
I'm still trying to sort this out... took a break for a while as I was/am getting frustrated
More so with my VPX tables stuttering than anything else, but back at the Pinscape...
Looks like all my RGB's are working except this pesky 4G. I'm not sure if it is my cheap multimeter or not, but I'm not getting the readings I'm expecting. When I set it to continuity my multimeter doesn't have the feature to actually make a sound, it just switches from a 1 to a 001 when I touch the two leads together. When I clip one lead to the JP11 Pin 5 and then start touching the other leads to the legs on IC7 I get several that register.To be honest I don't know which leg is leg 1. With the notch in the chip, does Pin 1 start to the left of the notch and then criss cross? If that is the case then leg 7, 8, 9 and 10 register 569 while legs 11 register 1198 and leg 15 registers a 002.
Needless to say I'm left confused
Because trying to figure out how to measure the leg from IC7 over to OK3 becomes really confusing when I don't know what leg is what number ![]()




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