HELP, Low output Guv'nor??????

[GVC]

I checked everything I can think of (Polarity, cold joints, values) and I am still getting a very low output when the effect is engaged.

http://www.generalguitargadgets.com/diagrams/guvnor_lo.gif

One change that I did make is the Chip is a 4558, would that do it.  The layout calls for the tl072.

Thanks to all of you!

[niftydog]

did you measure your resistors out of circuit with a multimeter? Lots of folks around here (including myself) have been in the same situation because we assume that band that looks brown is really brown and not a funny sort of orange! Plus, resistors can be damaged by heat and measure differently to how they are labeled.

[Mike Burgundy]

the 4558 is not the problem (unless the chip is sick or damaged),
Opamps have the same gain (it's set by the surrounding circuitry) as long as they can supply it. 072's and 4558's are directly swappable.
Is the sound okay? Does it distort? Does it distort at lower gain levels?
Do the voltages on the IC look good?
Resistors are a possible culprit, especially the ones with oranges and/or reds in their multiplier. Purple, brown, grey also tend to look alike sometimes.

[GVC]

Thanks guys,

Befroe I read your responses last night I did some testing and looking for cold joints.

The sound is slightly distorted with the level and the gain cranked.  but it does not sound like the cilpping is comming from the LEDs it seems harder than that.  when the level OR the gain knobs are turned down half way there is no sound at all.

Soooooo frustrating.   

[petemoore]

  Do the 'do's'
  Probe and take voltage measurements, these almost invariably will help identify the problem 'area'

[GVC]

Can I get a medium priced multimeter from Home Depot for this stuff?

If so does anyone have any suggestions?

[johngreene]

A cheap-o meter from anywhere would do for this kind of stuff.

Another thing you could try is to take the wire going to the output jack, disconnect it from the switch, solder a cap to the end of the wire.
Now you can take that and walk your way backwards through the circuit until you find your volume. Then you know the problem is just after that point.

As an example, I'd start by probing both sides of R12
Then to the wiper of the volume pot
Then to the wiper of the treble pot
Then to C12, C13
etc.

--john

[GVC]

Thanks everyone,

I found the problem: resistor attached to pins 6 and 7 was 680ohm instead of 680k

Now I believe this thing is working like the OG Guv'nor... but, I think it could be better.  I put a cap around the leds .0015 and that seemed to cut the fizz a little and I will experiment with iother values. 

The Main problem is the Volume of the circuit, and I have heard this before elsewhere.  The gain is at parity only when the volume knob is at 3:00???  What is happening there, the gain knob almost has more of an effect on the volume of the circuit?  The circuit also seems very midrangey even with the Mid knob cut (I have not decided wether this is a bad thing yet, but it would be nice to have a greater range in EQ).  In the little time I spent with it last night , I found it to only be usefull with the gain cranked to hide some of the harsh clipping (not able to get the nice near breakup sound that is more suited to my style). 

Any opinions, other observations from users, or mod ideas wanted!

Thanks again everyone!

[MartyMart]

The original is the same !
With gain quite low, you'll need level flat out, then there's some nice
"just breaking up" tones ... not much above unity though !
I like the following settings :
Gain at 2 o'clock
Bass at 1 o'clock
Middle/treble at 12 o'clock
Level at 4 o'clock
That nails a good Marshall stack, without getting too heavy.
It's probably due to the Led's, which makes the gain pot increase get much louder.
You could try a simple volume recovery transistor ( 2n5088) after the eq section
before the vol pot.
There's a few around on the forum.
Marty.

[GVC]

Thanks Marty!

At least I know I got it right

Maybe I need to spend a little more time with the Guv,  there are a lot of different sounds in there.

I did a search and have not found a whole lot in the way of Mods or experimentation, so in the mean time I will try to keep this thread alive as long as possible.