Aion Trivibe Trouble

[Carlinb17]

Thank you, I will discharge the caps and I will grab the r value of R25 and R26 with it off, power it, and check IC3 pin 1 for change. I will also report back the r value of R25 and R26 powered.

[Carlinb17]

sorry didn't realize it threw us on a second page.

[DrAlx]

And pin 2 should be a steady voltage value and match pin 3. If pin2  is being pulled to 0 then that explains the stuck state.

With no power on the board, check for continuity between Pin 2 and all the parts it is supposed to be connected to.
Also check pin2 is not shorted to ground by bad solder on it or one of the parts connected to it.

[Carlinb17]

caps have been discharged, powered off R26 67...K and R25 is 221...
resistance between pin 5 and 7 is 218k
pin 2 has continuity between c9,rate pot, and R28

powered
R26 is -326
R25 is -336
I'm not sure if I'm doing that right.

pins for IC3 powered

8
1 then drops to zero
4.38
0
7.65
3.98
8.17
8.77

I checked the voltage on the + on C9 it starts at about 1.79 the drops eventually to zero would this be a bad part its a 10uf.
C10 which is right after it hold steady at 8

I'm still not seeing the Led do anything and I'm not seeing any variation in voltage

[iainpunk]

can you measure the resistance between pin 1 and 2, without the IC in the socket, with the power off, and the rate knob at the fastest setting.
it should read 300k, or alteast within 5% of that.

cheers, Iain

[Carlinb17]

it starts out at 350 and goes up to about 420 slowly....

[iainpunk]

it goes up? if you keep the pot at the same position?

might be the capacitors charging, but still, the resistance shouldn't be more than 330k, never... what do all the individual resistors measure at? try measuring them form the legs of the components before and after that resistor you want to measure
measure R26 by putting the probes on pin one and the leg of R25, and the same way with the other resistors.

cheers, Iain

[Carlinb17]

they all appear be correct...

[DrAlx]

In a working circuit, the pin 2 voltage would always match the voltage at pin 3.
That low voltage value at pin2 makes no sense unless there are build errors (bad connection or short).
You basically have this according to the schematic and your measurements in the final stuck state.

8V (supplied from pin 7) --------R-------0V (input to pin 2)-------C--------8V (supplied from pin1)

(The C is two capacitors back-to-back of course, and R is the set of resistances made up of R27,R28,RatePot).

So current should therefore be flowing through R (from 8V to the 0V).
1) Confirm that you measure that voltage drop across R as follows:  Put one probe directly on the end of R27 connected to pin7 and the other probe on the end of R28 connected to pin2. ***Don't*** put probes on the IC pins themselves. Use the portions of the resistor legs that you see on top of the board.  The point of measuring this way is to check your soldering is OK.  i.e. that the two pin voltages actually reach R.  You should measure 8V or so across R.

2) The opamp input should draw hardly any current (if it's a working opamp).  We can't test that so have to assume that is OK.
Therefore that current that has come through R must flow into the capacitor C as it has nowhere else to go.
If current flows into the capacitor, then the voltage across the capacitor will change.
Since the right side of the capacitor is tied to 8V (due to the stuck state at pin1), then
for the voltage across the capacitor to change (due to current flow) means the voltage at pin 2 must change.
In a working circuit it would (until pin2 reached the same voltage as pin 3, which would happen very quickly) and then feedback would keep the pin2 and pin3 voltages matching.

So that stuck value of 0V at pin2 suggests to me that current is not flowing through R into the capacitor.
That could happen due to bad connection from pin2 to R or from pin2 to C.
Now you say pin2 voltage changed in time and eventually went down to 0 and stayed there.
So my guess at this point is that the connection from pin2 to C is actually OK (and that the voltage change you saw at pin2 was down to the cap charging up when pin1 got pulled high).  So my guess at this point is that no current is flowing towards pin2 from R.
i.e. bad connection on the  pin7-----R----pin2 side of things.

[DrAlx]

Hard to see in your picture but the track connecting R27 to the rate pot looks very faint compared to all the other tracks on the back of the board.

[Carlinb17]

thanks for guidance I will check those as soon as I can. Do you mean this area right here?(see picture) I should have continuity between the pin R27 and R28 that are connected right?

[DrAlx]

Yep that's the track. But before you go soldering anything please measure voltage drop across R as described (with one probe on leg of R27 and other probe on leg of R28). In other words, don't put probes on the common point between R27 and R28. Voltage drop when measured across the pair of resistors like this should be 8V because the R7 end is connected to pin7 (8V) and the R28 end is connected to Pin 2 (0V).

If it is 8V, then next thing to measure is voltage drop between the other legs of R27 and R28. Now those other legs should be connected to each other (by that faint track) and so should measure 0 voltage drop. If you see non-zero drop then it means the connection from R27 to R28 is bad.

[Carlinb17]

ok I do not I checked the leg side and the solder side there is no connections between these two points. Since they are close and supposed to connect would you recommend a solder bridge? And this might explain the pin 2 suck correct?

[DrAlx]

See what I added to last post. Yes they should be connected. Bit of scrap wire would do it.

[Carlinb17]

so the r value for the pins weren't adding up, they either jumped over 2m resistance or didn't register at all....

so I jumped the two points that appeared not be to connected after checking again that there was no connectivity between them

Happy to say that was it!

Thank you so much to everyone that assisted especially DrAix, your guidance and patience.

This one really made me question my build ability but in the end thankfully it wasn't my error just my delay and inexperience in not finding the issue sooner. I'm sure this will not even be close to the last time I have to reach out for help, so thank you all.

[iainpunk]

glad to hear that it works, it looks amazing!
i especially love that BC logo, very cool!

cheers, Iain

[DrAlx]

Nice one. It's good when theory works out.  Out of interest, why was there a missing connection.  Did the PCB come with a missing track or was the track somehow damaged by soldering?

[Carlinb17]

Nice one. It's good when theory works out.  Out of interest, why was there a missing connection.  Did the PCB come with a missing track or was the track somehow damaged by soldering?

Thats a great question. I'm going to reach out to Kevin at Aion about it. I've done several pedals using his PCB's and I must say the quality is excellent, the layout everything. Hopefully mine was a one off. I've never had an issue with my soldering (once I actually learned how to do it correctly and not to say I still can't mess things up now). The track appears to be there but maybe its just missing under the silicone or maybe it's a one off. It's certainly not something I've ever come across.

Either way it's on to the next one and thank you all again. This one was really making me go crazy.

[iainpunk]

you can PM AION through the forum, they are a member:
https://www.diystompboxes.com/smfforum/index.php?action=pm;sa=send;u=30498

cheers, Iain