Aion Eclipse, DC jack wired in wrong polarity -- help!

[slowpogo]

I built an Eclipse (15V configuration), plugged it in and turned it on to test voltage and the LED didn't light up.  Pumped the stomp switch a few more times and realized, I'd wired the DC jack center positive instead of center negative.  I may have smelt a slight whiff of burning parts.

I rewired the jack correctly, and this time the LED turned on, but I get no sound.  All parts are correctly installed.  What do you think happened?  Is it just a blown diode probably, or do I need to replace all the ICs?  Any help diagnosing is greatly appreciated!

*This is the third Aion pedal I've built and the first two worked perfectly right away.  I've also built headphone amps, DACs, a guitar amp, lots of mods, etc.  So I'm a fairly experienced builder but I know very little about circuits.

[bluebunny]

Welcome to the forum!

You could be lucky and the sacrificial zener has done its job.  Or you could have zorched your ICs.  You need to take some voltages to find out.  Check out the instructions in the sticky "Debugging" thread - it really works.  Then report back and we'll help you get it sorted.

[GibsonGM]

Welcome to the forum!

You could be lucky and the sacrificial zener has done its job.  Or you could have zorched your ICs.  You need to take some voltages to find out.  Check out the instructions in the sticky "Debugging" thread - it really works.  Then report back and we'll help you get it sorted.

Yup.  Read the thread, and see if you can post the voltages.  If you can provide a link to the schematic, that would be immensely helpful, too!

Take it one step at a time.  Welcome to the forum!

[slowpogo]

Okay, thank you!  Measurements are below.  While the LED was at least lighting up yesterday, it is not lighting today.  The measurements are the same regardless of the stomp switch position, although I double checked and it's wired correctly.

Schematic is in the instructions PDF: https://www.dropbox.com/s/5x723brxdo57va6/aion-eclipse-sdd3000-documentation.pdf?dl=1

Power source: 9.36V

+9V power input on PCB: 0.3
PWR GND on PCB: -9.0

Z1
Cathode: 0.30V
Anode: 0.0V

D1-D4: all 0.0V, cathode & anode

IC1 (TL072)
1: -0.29V (slowly dropping)
2: -0.28V (slowly dropping)
3: 0.0
4: -0.1V
5: 0.0
6: 0.0
7: 0.0
8: 0.0

IC2 (JRC4558D):
1: -0.2
2: 1.1
3: 1.15
4: -0.3
5: 0.0
6: 0.15
7: 0.15
8: 0.0

RG1 (LM7805)
1: 0.3
2: 0.0
3: 0.0

DC1 (NKA0515SC)
all pins 0.0V

[slowpogo]

BTW I tried this first with my Truetone pedal power supply, then again with a 9V battery.  Battery measured higher (9.5V) but the rest of the measurements were very similar (within a few hundredths of a volt).

[Slowpoke101]

The 9.1V zener diode Z1 is most likely short circuited.
The -9V reading on PCB PWR GND connection is probably due to a burnt (and open circuit ) PCB trace (track ) from that connection to the rest of the board.
Have a close look at the board and you may see evidence of burnt tracks.

[slowpogo]

Thanks for taking a look.  But I'm confused, as I don't see obvious evidence of these things.  There is no errant solder or flux or anything else around the zener diode that might short circuit it, it looks fine.

I do not see burnt traces near the power input.  The board looks fine.  There is some typical light flux residue but nothing that would seem to short things out.

[Slowpoke101]

When you applied power with the incorrect polarity the zener diode would have conducted significant current. This would have possibly overheated its diode junction to the point were it went short circuit. The zener may not have failed but I suspect that it would have.

Set your multimeter to a low resistance range and measure across the zener. Make sure that there is no power applied. If the meter reads near 0 ohms the zener is most likely toast.

Also, is there any possibility that you can upload some photos of the board? This can help to diagnose what is wrong.

[slowpogo]

The zener would not measure at low resistance; setting the multimeter to 200Mohm I got a reading of 1.1

Here are pics.  I re-flowed solder on the zener and the anode pad seems like it partially lifted, but it still has continuity to ground...measurements the same.

[slowpogo]

I just noticed the solder bridge between pads 1 and 2 on the regulator, DOH.  However I got rid of the bridge and measurements are the same.

[Slowpoke101]

Good pictures. Very helpful. They do show an area of concern - I will get to that shortly.

When you tested the zener (low ohms range on the multimeter ), you did not get any reading. That is good.
Just to make sure, set your meter back to the low ohms range and short the test leads together - it should display 0 ohms or very close to it.

Now (with no power applied to the circuit ) place the meter's black test probe onto the centre pin terminal of the DC connector and the red test lead to the PWR GND terminal on the board. You should see a reading similar to as when you shorted the test leads together. If there is no reading replace that black wire from the centre pin terminal to the PWR GND terminal.

Next step is to test the integrity of the board's ground connections. All this is to be done with no power applied and the meter on the low ohms range.

Check for connection between the tab of the 7805 regulator and the sleeve connection of the input jack - the meter should show 0 ohms (or very close to it ).
If it does then check for connection between the tab of the regulator and the Anode (non banded end ) of Z1 zener - the meter should show 0 ohms (or very close to it ).
If it does then check for connection between Z1 Anode and the PWR GND terminal - the meter should show 0 ohms (or very close to it ).
I suspect that it will not show any reading (open circuit ).

There appears to be some damage to the solder pads of the zener on the upper side of the board. A PCB track going to the anode pad from the PWR GND terminal may have fractured.
I note that you have removed the solder bridge from the regulator. Everything else looks good so far.

[slowpogo]

I went through all your steps, and they all read as they should, until the end between Z1 Anode and the PWR GND terminal.  There was no reading, an open circuit, as you suspected.

[Slowpoke101]

Ah, good. The problem is now localised.
Repair is simple; Solder a small length of wire between Z1 Anode and the PWR GND terminal.
That should get the voltages back to normal.
See if it helps.

[slowpogo]

You could say that "helped," the damn thing works!

Thank you so much for your help, kind sir. Were it not for you and this forum, I might have given up and used it for spare parts. Here it is in its finished form, making great sounds on my board. I call it the Korgi.

[Marcos - Munky]

Very beautiful box! How did you did the art? Hand painting?

Btw, even though is not really necessary, it's a good idea to remove the zener jumper you've added and put in a new zener. You won't have any reverse power issues if you use your power supply, but it's a cheap protection part that doesn't hurt to have in.

[slowpogo]

Thank you!  I used an acrylic paint pen by hand...I traced the corgi head around a line drawing I found online, which I printed and cut out.  I then finished with flat clear coat.  I was going to write "Volume" under the middle knob, but decided the "V" of the dog's ears did that job well enough!

I'll keep that in mind about the zener and order one with my next project.  In fact, since they're usually so cheap I will make a habit of ordering an extra one with each project, just in case.