Neutron Build Help

[crowsmith8]

So I tried my best to follow the directions for asking for help troubleshooting.  If I forgot anything just ask me to provide more details. 


1.What does it do, not do, and sound like?  It appears that everything works as far as functionality,I still have to play around with the settings more to make sure of this, but right now my biggest problem is that there is a constant high pitched whine/squeal.  It is almost always there, but it more aggressive with some settings.
2.Name of the circuit = Neutron Filter A Mutron III Workalike from GGG
3.Source of the circuit (URL of schematic or project) = http://www.generalguitargadgets.com/effects-projects/filters-envelope/neutron/
4.Any modifications to the circuit? I put  a 5k trimpot in place of the Rx resistor.  Also I used 2 VTL5C3 for the LDR
5.Any parts substitutions? The 150K log/audio pot was replaced with a 150K reverse log pot
6.Positive ground to negative ground conversion? N
***Note*** for this next question I don't have a 9 volt battery at the moment, so I took readings of the wall wart I am using in place of the battery
7.Turn your meter on, set it to the 10V or 20V scale. Remove the battery from the battery clip. Probe the battery terminals with the meter leads before putting it in the clip. What is the out of circuit battery voltage? => 8.95
Now insert the battery into the clip. If your effect is wired so that a plug must be in the input or output jack to turn the battery power on, insert one end of a cord into that jack. Connect the negative/black meter lead to signal ground by clipping the negative/black lead to the outer sleeve of the input or output jack, whichever does not have a plug in it. With the negative lead on signal ground, measure the following:
Voltage at the circuit board end of the red battery lead = 8.95
Voltage at the circuit board end of the black battery lead = 0

Q1
C = 8.85
B = 8.15
E = 8.95

IC1
P1 = 0
P2 = 0
P3 = 0
P4 = -8.26
P5 = 0
P6 = 0
P7 = .6
P8 = 8.85

IC2
P1 = 0
P2 = 0
P3 = 0
P4 = -8.26
P5 = 0
P6 = 0
P7 = 0
P8 = 8.85

IC3
P1 = 7.73
P2 = 2.5
P3 = 3.28
P4 = -8.26
P5 = 0
P6 = 0
P7 = .6
P8 = 8.84

IC4
P1 = 3.64
P2 = 4.62
P3 = 0
P4 = -3.95
P5 = -8.26
P6 = 3.77
P7 = 4.00 and slowly dropping as I hold the probe there.  It goes back up to 4.00 after taking the probe off, but always slowly drops when I'm taking the reading
P8 = 8.84

D1
A = 0
K = .6

D2
A = .6
K = .9

[PRR]

Please try with a battery. The internal voltage converter may be fighting the external supply. That could probably be fixed, but check with a battery.

Layout can be critical. Did you buy a PCB, make your own, or DIY a layout?

[crowsmith8]

I'll pick up a battery on the way home from work and re-post with new readings tonight.

I bought the PCB off of GGG so that it matched the project link that I posted.

[Giglawyer]

Did you do the jumper on the MAX1044?  There is supposed to be a jumper soldered in between pins 1 and 8 (I think).  I built one years ago, so I will have to check it out.  That might be your problem.

[crowsmith8]

I used the 7660 charge pump.  Would that jumper still apply?  And are you referring to jumpers that aren't part of the GGG PCB?

[Giglawyer]

Its been so long since I built this..let me look.  That said, which the 7660 could be the problem itself.  Check these out - http://www.diystompboxes.com/smfforum/index.php?topic=53972.0 and
http://www.madbeanpedals.com/forum/index.php?topic=18109.0.

[Giglawyer]

Also, look at page 4 of the directions.  You may have to remove the jumpers and install chokes to eliminate the whine.  Although, from the instructions, I am not clear as to what values you would use.  But, maybe you can PM R.G. Keen here and see if he has any advice.

[crowsmith8]

So with your help on where to start researching it does sound like the 7660 is where the problem lies. I've ordered the MAX1044.  I'll keep my fingers crossed that when it comes that will be the solution.  Thanks

[bluebunny]

I used the 7660 charge pump.  Would that jumper still apply?

The pin 1-8 jumper does apply to the 7660, but you need a part with an "S" somewhere in the suffix.  I would choose the 7660 over the 1044.  The latter is fragile wrt. input voltage.

[crowsmith8]

I have the TC7660SCPA, so I'll try the pin 1-8 jumper.  Thanks for the info.

[kerryandray]

Hi, Crowsmith

Did that fix the whine?  I am having the same issue

[crowsmith8]

Oh man, I feel bad for not having gotten back to this thread with an update and to dole out the appropriate thanks.

Anyway, yes this fixed my issue.  Thanks everyone for chiming in and helping.  I really appreciate it.

Kerryandray, hopefully this will fix your whine issue too.  Good luck.