402U not powering on

Wireless Receiver Kits
#1

Hi William,
I returned the 202U, purchased a 402U …I seem to have the same problem as I had w/202U, I am using the same AC adapter, I have 12.33 VDC on the power terminals (checked at screw terminal tops)
however, I have no power light, no 7-segment display.
While checking the power with a voltmeter, the power LED illuminates and I get a two-tone beep, but when I remove the meter probes the LED goes out, no power indication.

Experiment:

  • I tried holding the meter probes on the terminal again, while LED is on, I then hit the PGM button, I got the 7 segment display to illuminate and could scroll through selections.
  • I set 1 to remote “A” and 2 to “B” …it seemed to take OK.
  • I removed the probes from the terminals, power is connected, tried remote A/B …its dead again and will not respond.
  • Adding the meter probes back to the terminals, I get the PWR LED, beep, and I can get the relays to work with A/B remote (only if I continue to hold the probes on the power terminals).
    Conclusion: It looks like I need a small load (pull up resistor - maybe 10K?) across the power terminal to make the 402U happy, have you seen this? is it working correctly?
    Regards,
    John
#2

Well, this is indeed a weird case, but in my experience, power supply is likely to cause something weird like this.

I really don’t know why a resistor would make it work, but I would highly recommend you find another 12v dc 0.5a (or 1a, 2a) power supply, and try again.

If still doesn’t work after changed power supply, please take me a photo showing how the power wires is connected to receiver terminals.

And let me know, thanks.

#3

Ok, I switched out AC adapter for 12v battery, the same thing - only works with probes …pull up resisters don’t work either.
But by your message, “please take me a photo showing how the power wires is connected to receiver terminals.”
it sounded like polarity is now specific on the 402u - unlike 202u which is supposedly “don’t care”.

I looked through the manual again, as I did before when hooking it up, Nowhere does it state - or specify polarity, nor is it marked on the board
…just says “proper power” to terminals.

Anyway - I swapped polarity
Guess what

Duh! …should have tried that before writing this request instead of assuming it was like 202u (like the age-old did you check “is it plugged in”? question )
Works on battery and AC adapter now!
Thanks, William!
Works OK now!

JC

#4

Thanks John for let me know, and glad to hear it finally works.

And just let me know if you have other questions in future.

#5