4PM power issues

I’m at the testing stage of the build and I seem to be running into some issues with the power. I stupidly had the 7805 and 7905 swapped which may have blown one of them. I also realized too late that I put the IC socket for IC7 in upside down. I don’t think that matters, but I could be wrong about that. The red dots on the tests pass, the blue dots do not.

Power plug = 9.9V
D1 = 8.8V

1 = 1V
2 = 1.6
3 = 0
4 = -.6
5 = -2 and then drops to 0
6 = 2 and then drops to 0
7 = ranges from 1 to 0
8 = 9V


  • = 0

I = -2

0 = -.2


I = 0

  • = 0

0 = 5

The LT10541 is also getting super hot for some reason. I’m probably just going to replace the LT and the 7905, anyone have any other ideas? Thanks!

Great to see that you sorted it out yourself! Congratulations :slight_smile:

Once more over my shoddy soldering…and I’m in 4pole heaven! Jaw dropping! THANK YOU!

Alright! The replacement 74hc165 has arrived and my control board is now functional! No audio out though. I’ve probed the board and I’m not getting audio starting with the 3rd pole. What do I check from here? Thanks for helping me with every step Shruthiverse! :slight_smile:

The 7905 & 7805 are (in my experience) pretty difficult to destroy,
unless you deliberately hook something up wrong (in which case, they will explode, get super hot, and smell really bad),
the ic socket itself does not matter, as long as the ic is oriented correctly :slight_smile:

C31 was in backwards. Everything checks out now. I think I’m there.

Welcome to the Shruthiverse ™ as fcd72 would say :slight_smile:

Now it seems like half the power is dropping off over the power plug…what the heck…

Crappy power supply…switched to a 12v now…all tests have now passed but now the control board does not power up. I measure 5volts coming in from the filter but no LEDs light up. No short between ground and 5v. I have seen the LEDs flash for a moment on power up. Joins look ok to me. Anything else to try?

Retinned and its powering up now.

Spoke too soon LED 1 3 5 and 7 lit then a puff of smoke nooooo

did you divide by zero?

Do you still have LEDs 1 3 5 7 lit? Looks like the 74hc165 on the control board has been shorted - this is the part to replace…

If not:

  • Unplug the control board, are voltages OK on the filter board?
  • Plug back the control board, do you have +5V?

Sounds like that’s what I must have done. I was excited that it powered up and must have shoved a button into the voltage regulator. You couldn’t have been more clear about not doing that in the instructions. 1 3 5 and 7 are still lit although they faded out when the short occurred. They’re still lighting now though. Nuts.

Should there be continuity between GND and +5v on the filter board without the ICs installed?

No! It won’t be a resistance in the MOhm region either, but it seems you need to go over your board.

There is not continuity there so that’s good, and the tests on the build page pass. The only issue on the filter board is that the vregs get really hot (12v might be too much). The reason I asked is because there is continuity there on the control board.

7-9v is best. Higher the voltage the more heat the regulators give off.