🎵One of these things is not like the other! 🎶

[Pauleo1214]

Don't you love when your combo build works the first time, 75% of the time?

I am currently on a hot mess streak. My last four pcbs (of which I built successfully before) produce dry signal but no modulation.
I decided to focus on another weird build, four HAARPs in parallel. A QUAARP if you will. Except one of them doesn't produce any modulation. The PCB in question is the one on the upper left (component side up), upper right (pot side up).

So far i checked all my resistors, reflowed all my solder joints, checked that the ICs are getting proper voltage (they are), swapped the regulator and tl072's, and swapped one of the EEPROMs. No dice. Could anyone who is an eagle eye with resistor color bands see if I possibly subbed a wrong value? My next guess besides that is a broken trace.

 

[Pauleo1214]

@PedalPCB , is there a picture of the Rev. 02.01.20 board with component numbers? I ordered another board but would like to test points for continuity to see if this can be fixed with a splice.

 

[JamieJ]

After all you have already checked with circuit I would look at the FV-1 next in detail. Can you send us a close picture up of the FV-1?

Have you tried audio probing yet? That should isolate the problem more closely.

 

[music6000]

You need a better quality picture of the dud Board!

 

[Feral Feline]

The component-side pic won't zoom in for me, but all the other pics do.

Need a better close-up version of the component-side.

 

[Pauleo1214]

 

[Pauleo1214]

Apologies about the poor pics, I always struggle with getting crisp photos, especially within the size limits.


@JamieJ , I haven't tried probing yet. I wanted to know if there was a pic of the board with the component numbers instead of the values, it would make it easier to follow the schematic.

 

[Oh_Discordia!]

check the transistor - one lead isnt in the socket

 

[Pauleo1214]

check the transistor - one lead isnt in the

I accidentally pulled that out as i took the photo just now.

 

[Robert]

 

[Pauleo1214]

View attachment 25325

Thank you!

 

[fig]

Can you verify R9 R10 R15?

Looks like R18,R5 & R14 as well.

Probably just my screen colors...looks like double red bands

 

[music6000]

Can you verify that C4 is 1nF, it looks quite large in the photo & chipped????

 

[Pauleo1214]

View attachment 25327
Can you verify R9 R10 R15?

Looks like R18,R5 & R14 as well.

Probably just my screen colors...looks like double red bands

All 10K resistors.

 

[Pauleo1214]

Can you verify that C4 is 1nF, it looks quite large in the photo & chipped????

Yes, it is 1nf and has a "103" denotation.

I burned it because the 100k resistor gave an odd value reading relative to the other boards and i removed/ replaced it.

 

[fig]

Once I realized both ends looked red I figured something was up

 

[fig]

Yes, it is 1nf and has a "103" denotation.

I burned it because the 100k resistor gave an odd value reading relative to the other boards and i removed/ replaced it.

103 is 10nF right?

 

[music6000]

102 =1nF

 

[Pauleo1214]

102 =1nF

My bad, typo. I hit 3 instead of 2.

 

[fig]

Maybe the crystal?