phase 100 now there's phase

[soundcollage]

I finished the GGG phase 100 and added Mark Hammer's suggested mods: replaced the 4 way switch with a 250k pot  and 15k trim in series for resonance and a 1 meg pot for depth. I put the center frequency 20k trim on the front panel (for now it is a 10k pot but a 25k pot is on the way), and replaced r 19 with a 2.6k resistor and 10k pot for intensity. I am not hearing any phased signal, although the guitar passes through. I checked the ldr's and they are cycling and I can get it to self oscillate at high resonance settings. The speed and depth knobs change the rate and depth of the self oscillation but do nothing otherwise. Any suggestions?

[u1061810]

Hi,
 The one that I built from G.G.G. only works on a very narrow spot tuned in on the 20k trim pot, all the way to one end of the its rotation.

[soundcollage]

So, quite possibly the 10k pot I have in there temporarily is the culpret?

[u1061810]

This post has been changed. Wiring on GGG layout works.

[Boofhead]

So, quite possibly the 10k pot I have in there temporarily is the culpret?

I'd say that was a very strong possibility.  Last time I looked at this circuit there were some very touchy parts in there.

A better temporary solution is to add a 10k resistor in series with one of the "ends" of the trimpot ie. put a resistor between the trimpot and the point where it use to connect to.  This makes it look like 20k but with the wiper only swinging over 0 to 5, or 5 to 10 sort of thing. Which end I can't say: put it on one end and if that doesn't work move it to the other end.  If none of those connections solve the problem then you have got some debugging on your hands.  It would be mildly easier to debug with the 20k pot installed since you don't want the added uncertainty of which end the 10k resistor needs to connect to while you are debugging.

[soundcollage]

I changed the resistors to the values that u1061810 suggested.
R42-3k9, at GGG was 2k4 (didn't change this one)
R43-22k ...                56k
R40-47k ...                10k
R39-47k ...                10k
R56-4k7 ...                10k This one controls the speed . I used 3k here.

and I installed a 20k trim(replacing my temp. 10k one) --still no modulated sound, just unaffected sound and self oscillation if the regeneration is turned up. I noticed that previously the ground wire that connected the input jack to the board was not connected (although the wire running from the input sleeve to the outut sleeve was intact. When I connected this as shown in the parts layout the unaffected guitar that was passing through the circuit dissappeared and the volume of the self oscillation was reduced greatly. Hopefully this is a clue for someone. By the way u1061810 did you do all of the same mods as me?

[u1061810]

HI,
   I did two mods to replace the function of the switch.
 1. I changed R1 to 10k and wired a 100k pot ( I think Mark recommends a 250K-500k here , but I didn't have it),  as a variable resistor in series with it.This is the regeneration aspect of the switch ,located on the right side on the layout from GGG.
 2.I replaced the left side of the switch with a 500K pot to take care of the sweep function.(I think Mark Hammer recommends a 1M here , or toggle switch to serve this function.)


On your initial post you said you used a 10K pot for intensity control. I think I read this needs to be a 100k in value.( sorry if it's a typo.)


With the jacks it sounds like some kind of signal grounding out problem,  but not sure.
This is just a shot in the dark, but look closely at where you did that intensity mod , maybe there's a problem there.

Good luck!

[soundcollage]

For intensity I replaced r19 (6k2) with a 2k4 resistor and 10k pot wired as a variable resistor. Previously, I had a 1meg pot with the center lug going to c7 and one lug going to r18 and one going to r19 with a 100k resistor bridging from wiper to the r19 lug as Mark suggested for a blend control. I switched to the other during my debugging as it seemed to be simpler.

[u1061810]

What kind of ICs did you use ? I used TLO72s.
 Did you check if you are getting signal readings on all of them, maybe ones bad.

Did you try an audio probe on the circuit?

[soundcollage]

I used tl022's. I used an audio probe but the only signals I could find were uneffected guitar.

[u1061810]

It must be that the wet phase shifting signal is getting squashed somewhere in the circuit. Is the oscillation very loud, or weak and in the distance.
Maybe try the original resistor  for R19, without any mod there. I know R19 has a lot to do with the wet /dry mix.

Double check all your resistor values.
Does the 20K trim pot have any effect on the sound when it's turned?

I wish I could be more helpful. I know that effect is a big build.

[axis]

Have you tried the board in a closed up enclosure?
 
The Phase 100 I built from G.G.G. didn't work right unless the board was set in a certain spot in the enclosure and the back cover was on.(finicky bugger)

The LDRs seemed very sensitive to their position relative to the jacks, and even the sides of the box made them chatter, (noise and loud oscillation), if they where to close to them.

I don't know if this is relevant to your problem or not, just thought I'd throw it out there.

[soundcollage]

HAAA!! FOUND THE PROBLEM AND IT WASN'T MY FAULT. There was a small (smaller than a hair) short between two traces that was left from the etching process. Next time I need to pay closer attention to the boards if I purchase them. I knew I had done everything right. this is my 8th project and all others came out right the first time. I always check component values and continuity with my multimeter but I did not check the board (other than visually) this time. Thanks for everyone's help!  Thanks to Mark Hammer for his mod suggestions (they all work now by the way).
500k pot speed
1 meg pot Range
1meg (replacing r18/19) with 100k resistor jumping wiper to r19 blend
250k pot/ 15k trim series resonance(feedback)
50k pot center frequency (Mark suggested 25k-- 50k seems to work fine)

I have holes drilled for three additional switches that I have not put in.
1. lift  r18 for vibrato
2. tap at 5th stage for resonance(feedback)
3. add cap in series w/ resonance(feedback)

[u1061810]

Well allright !
   Hey, just curious did you change the resistor values back to the GGG board or not ? What size resistor did you use for R56?
I really like the sound of that phaser -nice and lush.

[soundcollage]

No, I did not change the resistors back, I kept them at the values you suggested (based on the ebay model). I believe r56 was somewhere around 3k2.  The blend control works much nicer than the intensity control. The mods allow for a wide range of tones.