Fuzzrite help needed

E9th
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Re: Fuzzrite help needed

Postby E9th » Sat Feb 05, 2011 8:47 pm

slapped in a 50K audio for the volume, no real diff from the 500K(350K with resistor). Then I attached a 100K resisitor across the two outside lugs of the 50K audio. No real diff. Its okay at max volume, but it shoould have higher volume overall I think. I wonder if my wiring is correct?

Mr. Bill
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Re: Fuzzrite help needed

Postby Mr. Bill » Mon Feb 07, 2011 11:16 am

I can't see all of your wiring, but it seems to be right. If it is working that's a good sign. The volume should be huge compared to the bypass volume, especially with the depth control maxed. They may be something wrong with the wiring or the board. Until you get the volume problem sorted out, don't worry about the pot values. Just focus on one thing at a time.

As for how the depth control works, this is normal. The output from the two stages of the circuit are out of phase with each other. When you mix the two outputs together in the middle of the rotation, the two out of phase signals cancel each other out, causing this effect. In fact when you tune in the quietest signal, where both signal are nearly equal, you get an octavia or frequency doubling effect.

Take a picture of the other side of the board and post it. I'd like to know the value of the resistors.

E9th
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Re: Fuzzrite help needed

Postby E9th » Mon Feb 07, 2011 12:32 pm

Thanks again Mr. Bill, I will take that photo and post it tonight when I get home from work (5 hours or so from now).

E9th
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Re: Fuzzrite help needed

Postby E9th » Mon Feb 07, 2011 6:01 pm

Heres that board shot:The one resistor whic cannot be fully seen is red, red, orange silver (or the reverse of that?)
Image

The one part of the wiring that I'm not sure was done correctly involves the three solder terminals at the top of this photo below.
The one on the far left goes to the tip of the instrument jack, and is met there by a wire coming from the top left footswitch lug. The other two terminals on the board go to the depth pot, the middle terminal goes to the left lug on the pot, the far right terminal goes to the far right lug on the pot.. The white chord that comes off the center of the front of the board in the previous pic goes to the far left lug of the Volume pot and is met there by a wire coming from the top middle lug of the footswitch.The bue wire connects the middle lug of the Dpeth pot to the far right lug of the volume pot. The middle lig of the volume pot is connected to the tip of the "amplifer" jack, where it is met by a wire comng from the lower left lug on the footswitch.
Image
Here is one photo I was working from to determine the wiring. Thanks again for guiding me thru this! 8-)
Image

Mr. Bill
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Re: Fuzzrite help needed

Postby Mr. Bill » Tue Feb 08, 2011 1:27 pm

Interesting board you have there. I haven't seen that version before. I guess they couldn't get 0.002uf caps, so they used two 0.001uf caps in parallel instead. All of your wiring is right.

The hidden resistor is 22K. It reduces the output from the second stage of the circuit so that it better balances with the signal from the first stage. On some versions this resistor is 33K. What does the resistor actually measure? That resistor is in parallel with the volume control and in series with the depth control, so the settings of the controls will effect the resistance reading that you get. The lower the value of volume control you use will cause more loss of output signal.

The cap that is on the footswitch is polarized. Is the positive side connected to the center two lugs?

E9th
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Re: Fuzzrite help needed

Postby E9th » Tue Feb 08, 2011 4:10 pm

The board looks similar to alot of the other masking tape covered ones Ive seen, but then i dont know much. The guy that sold me this thing, actually it was free with purchase of a Mutron II phaser and a Tel Ray oil can delay, said he gutted it to make a "switching box". Thats when he lost the pots apparently. I dont think the board has been altered in any way. m guessing he juts clippe dout the pesky components he didnt need :)


I knew that footswitch cap was polarized but had no idea which end went where, and dint want to stop the build and ask and wait for an answer, so i took a wild guess and connected the longer lead to the middle lugs. Is that the correct way to do it?

I will measure the resistor when i get home, but its often hard for me to get a good reading without them isolated from the other components.

thanks
-Ben

E9th
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Re: Fuzzrite help needed

Postby E9th » Tue Feb 08, 2011 8:16 pm

the 22K resistor measured 24K.

Mr. Bill
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Re: Fuzzrite help needed

Postby Mr. Bill » Wed Feb 09, 2011 11:01 am

The cap should be marked with a plus or a minus sign that relates to the leads. The positive one should go to the two center terminals of the switch.

I'm sure that your board is all original, my comment about the caps was only an observation. Most companies run into supply problems now and then. There are many documented cases of Fender amps having factory installed "wrong value" resistors, apparently due to supply problems. My guess is that they called the supply house for 0.002uf caps and found out that they were unavailable, so in order to fill an order they used two 0.001uf caps in parallel instead. The two 0.001uf caps are equivalent to the 0.002uf value, so the Fuzzrite works fine and sounds the same as all of the others, and they fulfill an order in a timely manner. This is not something that would be seen by the owner, so as the saying goes, when it comes to Mosrite specifications, anything is possible.

But now to troubleshoot the pedal. I assume the battery is fresh. I'd start by checking the simple stupid stuff that is easily overlooked. Measure the resistance of both switches to make certain that they are making good contact. They both should read the same as touching the two leads of the meter together. Check both positions of the footswitch. I've seen problems with these having too much grease on the contacts causing them to have a high resistance value. Check the wire that goes from the center of the volume control to the footswitch.

If all of the above is ok, then try jumpering the output jack directly to the output of the circuit, which you will find at the right terminal of the depth control.

Let me know what you find out.

E9th
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Re: Fuzzrite help needed

Postby E9th » Wed Feb 09, 2011 11:53 am

Thanks Mr. Bill, I appreciate the help. I will do the tests you suggested and report back tomorrow or tonight.

Brand new battery but I'll try another.

E9th
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Re: Fuzzrite help needed

Postby E9th » Wed Feb 09, 2011 7:03 pm

cap on footswitch is correctly installed.

with my meter set to 2M , whern I touch the probes together i get 0.
with niether probe touching anything I get 1.
with the battery switch set to on, I get 0 across the two battery switch lugs
with the battery switch off I get 1.
the wire from volume pot to footswitch i get 0 w/ battery on and footswitch on
I get .014 across the outer lugs of the volume pot with the footwitch and battery switch on.

I was not sure how you wanted me to test the footswitch? I dont really know what the individual lugs are for. which lugs should I attach my probes to?

with everything on I get -450 across the two top outer lugs.


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