Debugging Guvernör-Circuit

[redinch]

the junction between R11 and R12 reads 4.97V. 

[redinch]

GibsonMG - what do you mean by asking

Are you writing down your IC voltage just the way it REALLY is?

?

what is the "bias network"?

[antonis]

what is the "bias network"?

In your case, R11 & R12 which form bias voltage (4.5V) and R1 which "transfers" it to IC1B..

[duck_arse]

is there any mojo associated with the RC4558p? did you get it from musikding, or a guy on the interwebs? one possible explanation for the voltages is if your 4558 is not really a dual opamp, but "something else". it's been known to happen. do you have any other dual opamp on hand, any type number, you can try in the board?

[GibsonGM]

Yes, as Duck says, the chip may be "OFF".  Not opamp, or BROKEN.    A real, or functioning, opamp would be expected to try to keep the same voltage on each input pin, and yours is not.....I suspect your meter could be a slight issue here, too...4.97V would be consistent with the 10V you read for your power supply (battery), but is your battery REALLY 10V?  Or is it 8.9V?   At this time, the 4.97 reading is fine...we want to see that on the other input pin!



Side Note:  The bias network, R11 and R12, in this case (and in most but not all pedal circuits) halves the supply voltage so that the AC input signal can ride on a DC bias....it "shifts" the AC - which goes lower than zero volts and our battery does not - "up" so that the chip can amplify correctly.   The input and output caps "remove" this DC (as mentioned, they block DC), returning the AC signal to its original "moving around zero" level, but amplified.  The capacitor in the bias network  'smooths' the power supply to ensure it is straight DC, and also to supply any sudden demands for current; it is a reservoir, or filter, capacitance.

[redinch]

I managed to purchase an opamp at a local dealer, rushed home and inserted the new IC ...

YEAH - We finally got it working!!!

Thanks to all of you! Thanks for your patience! 

Now i have to put it into the case and play it.

... and think about what to build ( and now hopefully debug on my own  ) next.

For completeness - now the voltages are:
IC1:
pin1=4.91V
pin2=5.05V
pin3=4.93V
pin4=0.00V
pin5=2.59V
pin6=5.24V
pin7=5.24V
pin8=10.10V

[GibsonGM]

Great! Glad to hear it!     Make an audio probe anyway, Red - you will need it.   And you can use it right now to listen to your circuit and hear what it is doing!

Just don't short out the pins of the chip while you do so     Happy building!

[antonis]

Make an audio probe anyway, Red - you will need it.

Do I discern a faint disbelief for other people's populating/soldering skills, Sir.. 

[duck_arse]

excellent. next question, how far can you throw a fake opamp? (and where did you get it from?)

[GibsonGM]

Make an audio probe anyway, Red - you will need it.

Do I discern a faint disbelief for other people's populating/soldering skills, Sir.. 

Absolutely - I have used one many times myself.  You have not, Antonis? 

[redinch]

The opamp came with board and other parts from musikding. Yet i never had problems with musikding. Great shop. Maybe i ruined it myself.

... and yes i will do an audio-probe. With the IC, yesterday i also got a cap for the audio-probe cable. For the last audio-probe i had to unsolder a cap from my muff ... 
Today i put the guvernör into enclosure and fiddled around with some sounds. It is fun - but feels like it  could be a bit louder 

[GibsonGM]

You could make a booster to use after it, if you feel you'd like more gain, provided it doesn't have any other issue (ha ha).

The IC may have come from the factory damaged - that happens rarely, but it DOES happen....or else maybe you DID mess it up!   We've all done that once or twice      

What voltage rating is your audio probe cap?  When I first started, I used something like a 25V rated cap, and that is fine for 9 or 18V circuits.  Then, to audio probe TUBE AMPS (which often run at 400v or more), I made sure to get a cap rated at 600V, for safety's sake...it is something to keep in mind.

[redinch]

The audio probe cap has 250V rating.

For now i can't find any further issue.

[antonis]

You could make a booster..

We all wish you quick mind recovery for the new year, Sir...