Dallas Arbiter Fuzz Face almost no volume

[eskimoquinn]

Hey Folks,

Working with a stock version of the circuit here:
https://www.dropbox.com/s/gf1adkf9upq5xds/aion-solaris-fuzz-face-documentation.pdf?dl=1

Something definitely wrong with my circuit that I cannot figure out. Have checked for backwards orientation of components, tried trouble shooting with an audio probe to no avail. Basically I hear almost no sound in the output and definitely no gain after the transistors. The voltages on the transistors are also strange:

Q1: C 5.5, B 5.3 E 3.9
Q2: C 4.8 B 4.2 E .5

The strangest thing of all is that this pedal did work when I first completed the circuit. Here is the picture of the circuit just in case I missed something obvious, definitely been staring at it too long.

[MaxPower]

The first thing that sticks out is the difference in voltages between the collector of q1 and the base of q2 since they are connected to each other.

[GGBB]

Are those positive or negative voltages? Either way they don't make sense.  What is the voltage on pin 5 of the IC?

[pinkjimiphoton]

Hey Folks,

Working with a stock version of the circuit here:
https://www.dropbox.com/s/gf1adkf9upq5xds/aion-solaris-fuzz-face-documentation.pdf?dl=1

Something definitely wrong with my circuit that I cannot figure out. Have checked for backwards orientation of components, tried trouble shooting with an audio probe to no avail. Basically I hear almost no sound in the output and definitely no gain after the transistors. The voltages on the transistors are also strange:

Q1: C 5.5, B 5.3 E 3.9
Q2: C 4.8 B 4.2 E .5

The strangest thing of all is that this pedal did work when I first completed the circuit. Here is the picture of the circuit just in case I missed something obvious, definitely been staring at it too long.

either the charge pump is shorted or blown, or one or both of the q's may be toast. my money is on the charge pump.
the q's aren't biased on to an operational state i don't think
cuz no way you should be getting 5 volts with a charge pump, npn or pnp it should be around 9v

[eskimoquinn]

Pin 5 has 9.1 volts coming out.

[GGBB]

Pin 5 has 9.1 volts coming out.

Positive or negative? Where are your meter probes when you measure this?

[George Moore]

Q1 ground connection
.

[GGBB]

Q1 ground connection
.

Q1 does not connect directly to ground, so please be more specific.

You are going to need to be a little more forthcoming with details if you want us to be able to help. Which probe was connected to where? Positive and negative indications are important. Since this is a negative supply (aka positive ground) circuit powered from a positive supply fed charge pump delivering the negative power, it is very important that you keep track of the polarity. If the charge pump has failed as jimmy suggested (and I also think this is what has happened), you may be getting positive voltages where you think you have negative. But because you aren't being specific about your measurements, we can't know for sure. The most puzzling part so far is what MaxPower noted:

The first thing that sticks out is the difference in voltages between the collector of q1 and the base of q2 since they are connected to each other.

In theory, different values for Q1C and Q2B is impossible, so we need to know where and how you measured things to determine what mistake you made.

[Electric Warrior]

Q1 ground connection
.

Q1 does not connect directly to ground, so please be more specific.

It's emitter should connect directly to ground.

[GGBB]

Q1 ground connection
.

Q1 does not connect directly to ground, so please be more specific.

It's emitter should connect directly to ground.

Have a look at the schematic in the build document posted at the top of the thread. That's the actual circuit in question.

[pinkjimiphoton]

he says he built - i THINK- the stock circuit.

that build doc, tho its nice it included directions how to build it all the way into a wolf computer,  is a little hard to follow.

but yeah, we need specifics. did you go npn? pnp? negative or positive ground?
the voltages you give us positive or negative?

lotta fuzzmongers here wanna help, but we need YOUR help. pics would help too sometimes.

but i'm betting theres an issue with the q's. if ya soldered them in, a lot of times they will die from the heat. i'm talking 2 seconds is enough to destroy them in some cases.

so anyways, please give us more info?

[GGBB]

Judging from the build pic and comparing with the doc, it looks like it is PNP (charge pump included, no "NPN" jumper, etc.). But we need confirmation - and voltages with polarity.

And yeah that doc is hard to follow because of all the configuration options. That seems to be one of Aion's things - variable configuration options - and probably why there seem to be a lot of Aion troubleshooting threads here (a lot more than other PCB brands at least). Or it could be that they sell way more PCBs than anyone else.

[eskimoquinn]

So I had an extra charge pump lying around, and sure enough, beautiful fuzz.

Just to close out the questions that were asked, all those voltage readings were positive the first time. Also this was a PNP config.

Is it possible/probable to fry a charge pump with a cheap wall wart? Friend of mine was using this pedal and when it came back it was not working. Wondering if a bad wall wart could do this.

Thanks everybody for the help!

[GGBB]

It's possible to fry a charge pump with any power supply, if the power coming out of it is "wrong" (too much voltage, AC, wrong polarity), and if the charge pump isn't adequately protected. This PCB has reverse and over voltage protection by way of the 12V zener D1 (looks okay on paper). The absolute maximum input for the 1044 is 13V. That's cutting it too close if you ask me. "Cheap" wall warts are usually unregulated, so it is conceivable that a ~9V supply could put out more than 13V at currents well below its rating. Or it might have been reversed - not sure how the 1044 would handle negative power in, but I fried an LT1054 once just by putting it in the socket backwards. Check that diode - it obviously didn't perform as intended - and find out what the friend used to power it.

[pinkjimiphoton]

i've had charge pumps die just by bumping against the case a couple times.
most likely he used an ac adapter instead of dc from what you describe. yeah, a wrong adaptor can easily do it.

if you're using the charge pump tho, i don't get it... did you use the cp to run the q's as a pnp circuit? or did ya run pnp q's with a negative ground with the cp? cuz to me that seems like... huh?

glad ya got it sorted out!