FV-1 No audio out of pins 20 and 28...

[ProfSkibs]

Working on a new build... having issues. Made an audio probe, and trying for the first time. I have audio going into Pin 1, but nothing out of Pin 28... I also have audio into Pin 2 and Out Pin 27. Im finding any components directly downstream from Pin28 with no signal. Components around IC3 are a little wonky too, but Im chalking that up to its location after the FV-1 chip. Also, not getting any signal out of pin 20, which looks like its attached to the tip and switch. Not sure what to do next. Any help would be appreciated. When I probe pin 27, I get audio and some of the pots on the pedal function. Im working on the Leprechaun. Does this pedal use both pins 27 and 28 for output? Schematic I was given looks like it does, any friendly advice would be appreciated. Trying to avoid having to resolder a replacment FV1....Im lost here guys, I could use some help.

Thanks

 

[p_wats]

Did you solder the FV-1 yourself? In my experience, 90% of FV-1 issues are from self-soldered chips (I speak from experience). If yes, I would ensure there are no bridges and all pins are making a good connection---do you have have a multimeter to test continuity? You'll want to check that each pin connects where it should in terms of the schematic.

You should get audio in at pins 1 & 2 and out at 27 & 28.

You also need to ensure the chip is getting proper voltage---measure pins 4, 6 & 8 to ensure they are all 3.3v.

Not impossible to solve! Just start by checking the above.

 

[zgrav]

Confirming you have an incoming signal on 1 and 2 is good. Same goes for having a signal on pin 27. Check to see if pin 28 of the FV-1 is connected to ground. You may have a signal coming out of that pin but being shorted to ground on the PCB.

 

[ProfSkibs]

Did you solder the FV-1 yourself? In my experience, 90% of FV-1 issues are from self-soldered chips (I speak from experience). If yes, I would ensure there are no bridges and all pins are making a good connection---do you have have a multimeter to test continuity? You'll want to check that each pin connects where it should in terms of the schematic.

You should get audio in at pins 1 & 2 and out at 27 & 28.

You also need to ensure the chip is getting proper voltage---measure pins 4, 6 & 8 to ensure they are all 3.3v.

Not impossible to solve! Just start by checking the above.

I have checked audio. Pins 1 and 2 get audio. Pin 27 has output. Pin28 does not. For power
I had tried previously, but couldn’t get consistent readings. I’m pretty new to this whole building thing. With the DMM where should I be putting the probes? I’m assuming black goes to main ground on the output jack or negative pcb pad. If the chip isn’t getting proper voltage on this pins...where I look? I checked the board it seems to have power. The L78 is doing its regulating thin 9v in and 3.3 out... this is the first pedal I’ve had to troubleshoot and it is kicking my a$$

 

[ProfSkibs]

Confirming you have an incoming signal on 1 and 2 is good. Same goes for having a signal on pin 27. Check to see if pin 28 of the FV-1 is connected to ground. You may have a signal coming out of that pin but being shorted to ground on the PCB.

Would you mind telling me how to check if it’s shorted to ground? This is my first attempt at troubleshooting and I’m failing...badly.

 

[zgrav]

Here is the general approach and why you are testing this: Set up your digital meter to measure resistance. put one probe on a known ground location and the other probe on whatever pin you are testing on the IC. A zero or very low resistance reading shows that any output from that pin could be going to ground. Then you use the schematic to start checking things connected to that pin to figure out where that short to ground is located.

 

[zgrav]

also -- be sure to start reading the forum posts here for getting started with builds and troubleshooting them. lots of great tips there to help you along the way.

 

[ProfSkibs]

also -- be sure to start reading the forum posts here for getting started with builds and troubleshooting them. lots of great tips there to help you along the way.

Thanks. I've been reading and reading and lurking the leprechaun and fv1 posts. I was asking about the ground issue, because I thought I knew what I was doing before this build. THEN this build happened and whew...I was wrong. I am going to have to go back to my multimeter and try again. I was getting inconsistent results and then put things aside for a while to prevent rage quitting...