Hi, I have build the spatialist reverb from PedalPCBs, which is based on the FV-1 chip. The link goes to the arachnid, but as I understand it, those are the same, only differ in the software on the eprom. So, my problem is, that nothing happens if I plug in the 9V plug, no LED lighting up if I push the button and no sound. When I measure the voltage at the input (directly at the 9V plug) I only measure -1.6V (the wall plug is good, it puts out 9V if not connected and also drives my keystep). Any ideas what could have gone wrong there? What can cause the voltage to go from 9V to -1.6?
+9 to negative −1.6 with that circuit? Nothing, what I can see. Are you sure you’re measuring against the same 0V/ground? With everything turned off, do you have continuity from positive in to the 3.3 regulator input, and from negative to regulator ground? With it plugged in, what are the voltages around the 3.3 V regulator? (in and out, relative to the middle pin; see pinout below)
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I have continuity for the ground, and also from the +9V input to the diode, but not after the diode, when I measure the resistance over the diode, it has 7k… is that expected? When I measure it the other way (putting the red multimeter needle on the side of the stripe) the resistance is ‘infinite’. I noticed that there might be a problem with the orientation of the regulator on the pcb vs in the schematic, I will check that now…
Yeah, looks like I had this one reversed! But now I measure 6V at the output of the regulator and not 3.3V :-/ maybe I damaged it when I put it in reversed… I will check again on a breadboard to not damage the rest the reverb.
The diode shouldn’t drop much at low currents (datasheet says ~0.5 V at 1 A, less at lower currents; see below). Does your multimeter have a diode mode? It might just be that the resistance mode (which usually uses constant current through the resistor) gets confused by something.
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Well, 6 V is about what you’d expect it to drop with 9 V in, so make sure you measure the voltage between the right pins. Verifying things on a breadboard sounds like a good next step!
I have a multi function tester and it says Uf=281mV Ir=0.64uA for the diode, whatever that means, I need tu study the dataset…
Yeah, maybe I got confused with the measuring, but I was a little afraid to destroy the rest of the circuit with the 6V… On the breadboard the regulator outputs 3.6V when I give it 5V input, but I have not added the capacitors, so just the regulator alone, which might not be a good idea and I also need to check with 9V in…
With 9V in, it puts out 7V… so I probably killed it! 
If that was all, I would be okai, but if I killed all the ICs on the board… need to get a new regulator now
looking back at the PCB, I think they have got the silkscreen of the L78L33 wrong, because the 9V go through the diode and then go to the right leg of the regulator, which should be the output, if you put the flat side towards south, as in your diagram… I have seen some pictures of this board where people have soldered it like this and it worked apparently…
BTW: Thank you very much, fredrik!!
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Got new L78L33 a few days ago and checked again. It was working!! But after I reinstalled everything in the case, no more
Not even the LED, so I hope it is some simple thing with a broken cable or something. But when I got out my multimeter I noticed I forgot to turn it off and the battery is dead -.- stupid me! Now I first need to get a new battery and then work on this again…
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