The Phase 90 chursed...

[Ark Angel HFB]

I'm using fairly match Qs and I've reflowed solder twice to fix small problem...

But the real kick in the pants seems trimmer pot that seems to be buggy... sigh will replace and see if it fixes the problems... if not then I'll post voltages and maybe you dudes can give me a hand.

[Ark Angel HFB]

Ok I need some help...

Currently the circuit is passing signal and it is around unity, but I'm not getting the phase sweeping effect.

I think the problem is in the trimmer pot area. I notice that as I am turning the pot pot I get the phase effect.... which I guess would be normal. Also When the screw driver is turning the knob and I hold the screw driver and touch the guitar string I get the effect for a bit... I think all I'm doing is shorting the pot to ground and that is changing resistance and giving the sweep effect... will post voltage in a second... just got into a LoL game.

[jimilee]

Got pictures and sus you check the pinout of the fets? What layout are you using?

[pinkjimiphoton]

SQUASH THAT BUG!!

http://www.diystompboxes.com/smfforum/index.php?topic=29816.0

for now, replace the trimmer and see if it works. check the zener diode in the circuit...

but we need voltages, etc

[armdnrdy]

But the real kick in the pants seems trimmer pot that seems to be buggy

By "buggy" if you mean moving in and out of a distorted sound, than it's working fine.....that's normal.

Jimi's advise is correct, assuming you're using a 5.1 volt zener, try changing it to  4.7v or 5.6v.

[Ark Angel HFB]

Ok inc voltage reading...

http://www.sabrotone.com/wp-content/uploads/2010/08/MXR-Phase-90.gif Here is the vero I used...

Anyway the ICs had the same voltage reading except for IC3 Pin 3 and Pin 5 which was a little lower.

IC 1 & IC 2 =  1(5.05) 2(5.05) 3(4.95) 4(0.00) 5(4.95) 6(5.05) 7(5.05) 8(8.05)
IC 3           =  1(5.05) 2(5.05) 3(3.42) 4(0.00) 5(4.45) 6(5.05) 7(5.05) 8(8.05)

Q 1-4 All had the same readings... honestly pretty happy with the match job I did.
D: 4.95
S: 5.05
G: .066 to 2.85 depending on where the trimmer pot is set.

Q5
E: 5.05
B: 4.46
C: 3.24

Anything else?

OH OH one more thing... the Rate pot doesn't do a damn thing(didn't move it during voltage test so it might change a voltage) but the switch for script/block does change the sound a bit... just it is very subtle... and completely a mute point without the phase effect.

[armdnrdy]

You should have oscillations on IC1 pins 5, 6, and 7.

Look for a bad solder joint or a solder bridge.

Even if you looked before.....look again.....closer.  

[jimilee]

Also that layout has some hidden cuts you can't see. Under D2 for example

[Ark Angel HFB]

I C... see what I did there...

I'm aware of the under cuts... I copied that Vero Design over and built from this


Do you see any problems with it? All I did was add an extra line and change where the ground came in so that i could add some better power filtering.

Also... What would cause the lack of oscillation? could it be a bad chip?

[armdnrdy]

A bad IC is always the scapegoat! 

Look for a cut that is not "cut" completely, bad solder joint, ect.

[Focalized]

I had trouble with this layout. I scratched and rebuilt and it works great now.

My problem the first time was that it would phase but there was a volume drop with noise every couple seconds. Never knew why. I know that doesn't help you but my point is it's probably a mistake you haven't found yet. Same as what I was told.

[pinkjimiphoton]

the phase trimmer should be best somewhere around the middle. you can set it by ear... listen thru your amp CRANKED UP a bit CLEAN and listen to the phaser..
too much to the let or right it will get fuzzy and cut out. you wanna tweak this til you get the most phasing with the least noise and the least distortion.
that's right.. it's gonna be a compromise to a point.

looks to me like there's a voltage problem on that last ic... i bet there's a tiny bridge somewhere you can't see without really looking for it...hard

[Ark Angel HFB]

the phase trimmer should be best somewhere around the middle. you can set it by ear... listen thru your amp CRANKED UP a bit CLEAN and listen to the phaser..
too much to the let or right it will get fuzzy and cut out. you wanna tweak this til you get the most phasing with the least noise and the least distortion.
that's right.. it's gonna be a compromise to a point.

looks to me like there's a voltage problem on that last ic... i bet there's a tiny bridge somewhere you can't see without really looking for it...hard

Right, but above someone said I should be getting oscillation on IC1... pin 5, 6, & 7. All voltages everywhere are stable.

Let me restate... the circuit is Passing signal... it is at or above unity... turning the trimmer(changing the resistance to ground) give the effect as you are turning the pot...

Since I am assuming the rate knob control the part of the circuit that make it oscillate and the rate knob currently does nothing... what part of the circuit is responsible for the oscillation that should be the area to look for problems?

Is the 2n4125 the Q that controls the oscillation of resistance to ground?

[pinkjimiphoton]

ARE you getting oscillation there? if so, then the phaser's sweeping, and the problem is somewhere in the audio path, probably the mixer stage.

the oscillation looks like the voltage jumping all over the place... if you're getting that, try replacing that last opamp.

[armdnrdy]

IC1B (pins 5, 6, and 7) is the LFO IC.

The above pins should not be "stable." The voltage on these pins should be moving up and down.

Look for the problems I mention above and that C10 is oriented correctly.

Did you socket the ICs or solder them?

Any chance of pictures of your build?

[Ark Angel HFB]

IC1B (pins 5, 6, and 7) is the LFO IC.

The above pins should not be "stable." The voltage on these pins should be moving up and down.

Look for the problems I mention above and that C10 is oriented correctly.

Did you socket the ICs or solder them?

Any chance of pictures of your build?

I'll post pic but they won't be pretty... in trying to solve this I've solder and re-solder a few times and so thing are a bit less net than I'd like... gezz I feel like I'm a teen again and my buddies just walked into my dirty bedroom. lol give me five minutes

[Ark Angel HFB]

Battery for my cam is still charging... might be time to get a new one.

Anyway I re-check again heated my iron ran it between the track to make sure there were no solder jumps...

I re-checked the voltage reading again and there is no oscillation of an kind anywhere.

got frustration so I'm jumping in a LoL game and then I'll try changing the ICs and taking pics for you guys.

[Focalized]

I forgot to mention a problem with my second try with this and it sounds like the same problem If I understand what you said.

I did forget the cut under D2 and the phase would only work as I turned the trimmer. Try around there again. to make sure the cut is clean.

[Ark Angel HFB]

plz don't judge me... it was clean and neat once... T_T

To make larger... right click and hit open in new tab... that will give them to you really big.

I didn't have a 15uF cap so I paralleled a 10uF and a 4.7uF...

[Focalized]

Why did you convert the layout? I mean that's ok to do but it'll make it very hard for someone to look for a problem visually. Meaning one would have to trace the verified layout to verify yours first, then check out your build.

What's going on with IC2? How you used a IC socket then used the DIP sockets with the transistors.

Sorry I can't help really, a bit too hard to tell what's going on. I want to help as I don't get to often but having built the layout twice with one fail and a success I thought I'd chime in somehow.

Tip on the jumpers, don't worry about stripping insulated wire for the smaller jumps. Just use some component clippings. Easy bend and solder.