Shruthi switch short?

On my 4 poles mission control board. Just finished building it.
The LED 7 is always on, I checked the switch 5, it’s OK
I removed it and removed the LED.
I checked on the board between the pad 1-3 it’s short, pad 2-4 short, pad 1-2 short, pad 3-4 short…
it’s also short between negative pad of the LED and all the switch pads on the board
What can i do?

Maybe there’s something wrong with the resistor network causing all switches pads to be shorted to ground? Is it correctly soldered? Maybe you could post a photo of your board to help us…

the corresponding pins of the resistor network and the switches seems to be OK.
except for the S5 all the four pads are short to the resistor network corresponding pin :frowning:

Whew, quite a few solder joints on that board that i wouldn’t trust ! :confused:
I would start adding solder to the three pads at the right of the resistor network on the second photo (top three on the third photo)…
And pretty much every pad on the third photo - The solder is supposed to make a “tit” like shape, and it’s not like solder costs a lot, so why risk not using enough & having to spend hours troubleshooting?

Do you also detect a short between GND and +5V?

no short there

@Vcent i’ll put some more

What is the resistance between pin 1 of the resistor network and the other pins?

They all have 9.94K except the pin 6 have 1.32K

And resistance between each pin of the resistor network and ground?

They all have 11.30 but pin 6 have 0.00

I have a spare resistor network, i tested it and between the pin 1 and the other pins i have 9.92K all the way.
Is it a good idea to change it or i’ll better check something else before?

You may as well solder a single 10k between the common Pin and Pin 6 if you are not that confident with desoldering.

Can you check that there’s definitely no solder bridge between S5 pad 2 and the negative pad of led 7 ?

@ByteFrenzy, no solder bridge there

Do you think the fact that the resistor bridge pin 6 have a different resistance, can make the short between the pads 1 and 3 on the switch 5?

I think that you’re measuring different resistances on the different pins because there is a short elsewhere, not because of a defect in the resistor network. The points I mentioned were rather likely candidates. Otherwise the 74HC165 could be faulty. Are you certain the two boards did not come into contact with each other when you powered them up?

I just removed the resistor bridge and there is still short between all the S5 pads and the pad 6 where the resistor bridge goes.
Is there a way to test the 74HC165?
Thanks for your help

Yups, replace it. If this works the 165 was faulty.

Or remove it and see if the error is still the same: some short circuit or other soldering error, or you got a faulty or not properly seated IC.

Yeah! Finally, it was the 74HC165. It’s good to get some spare when ordering at Mouser… :slight_smile:
Big thanks guys for helping!
Here is a picture of the work and progress