MXR Phase 45 now works

[skyhigh]

my MXR Phase 45 won't work at all
trim was set to middle and was a 300k
it seems to be about 8.4V everywhere this pcb is one of my best soldered, ever, so i'm pretty upset when it dont work

here is the schematic: http://www.tonepad.com/getFile.asp?id=12

Q1 2n5952 (matched)
g = 8.4
s= 8.3
d = 8.5

Q2 2n5952 (matched)
g= 8.3
s= 8.3
d= 8.5

IC1 (4558 the one to the left on layout)
P1 8.4
P2 8.4
P3 8.3
P4 0.0
P5 5.2
P6 8.4
P7 8.4
P8 8.99

IC1 (TL072 the one to the right on the layout)
P1 sweeps between 1.3 - 8.4V
P2 sweeps here to
P3 sweeps here to
P4 0.0
P5 8.3
P6 8.4
P7 8.4
P8 8.99


Z1 (zener 4.7)
A = 0.0
K = 8.5 (hmm, pretty high compared to RDV's voltage)


thx

[RDV]

Here's the pin voltages of my functioning Tonepad Phase45:

IC1
1. 3.53
2. 3.52
3. 3.52
4. 0
5. 3.37
6. 3.52
7. 3.52
8. 9.73

IC2
1. 3.53
2. 4.60 - 5.35
3. 4.32 - 5.41
4. 0
5. 3.52
6. 3.53
7. 3.53
8. 9.72

Q1
D. 3.52
S. 3.52
G. 3.52

Q2
D. 1.35
S. 3.52
G. 3.52

Zener Diode Cathode End
3.52

Pins 2 & 3 of IC2 are the oscillator which when working are both constantly changing in voltage. If you're getting a steady voltage there, it's not working. I'd also go get the correct value trimmer to just be sure.

Hope this helps.

RDV

[RaceDriver205]

Flip the 2n5952s around, then let me know if this worked. (Some tonepad layouts have this issue).

[skyhigh]

I'd also go get the correct value trimmer to just be sure.

well after reading the build reviews at tonepad they recomend a 500K trim?

im not so good at electronics (but all my other pedals worked at first time though) but isn't the potential at the +9V in's 10k resistor (resistors other side) the same as the drain at Q2???(the purple outlined) it goes through 10K resistor and all the way down/around and up to Q2's Drain?

i thought if i could get 3.5V (as RDV has) there, i would be on my way because there is only one resistor between +9V In and Q2's Drain OR AM I COMPLETELY OUT SAILING?  the 10K says brown black orange

[RDV]

I just went back and found my post from a couple of years ago(cause I thought the voltages might help) and copied it which is why the blurb about the trimmer is there, that's not your problem, your Zener probably is, it's either backward, not functioning, or the wrong one.

RDV

[RDV]

Did you buy a PCB from Francisco? Or did you make your own? These things count.

RDV

[skyhigh]

i did my PCB from tonepads layout and it was very fine after i etched it.
some recomend a 500K trim so i think my 300K must make some sort of noise

does the zenerdiode make the voltages that the purple outlined potential has?? i have to many 8.4V places

[RDV]

Your zener should show something close to it's rated voltage at the cathode end, if not then something's wrong and all your other voltages will be wrong.

RDV

[skyhigh]

yep!! that makes sense even to me 
i have soldered 2 socket pins for the Zener diode now and i will look in my desk if i have any proper one.

thx RDV! i'll go with this prob error and see what comes out of it.

[skyhigh]

yes, you were right RDV. it was the Zener.

+ the transistors had to be turned around as Racedriver205 mentioned.

well, well.... it ended up the way that i now have 2 easyvibes !??? i can't hear any difference between these two pedals (counting out the chorus switched in on easyvibe) hmmm??? this wasen't what i expected but shit happends  i have to sell one of them

[RDV]

Cool, it's been a while since I actually helped someone get an effect going. I didn't know if I(still) had it in me.

I guess I do.

RDV

[skyhigh]

yep!!

I'll just blame Banzai for sending me the wrong Zener diode - or a bad one? (it didn't show any voltage on the diode)
Now i have a 4.7V zener and it works. i just paint and box this and start thinking which pedal i will keep 
b.t.w the IC2 sweeps at pin 1 also. from 1.3 up to 7.9V. pin 2 and 3 has 3.9 - 5.4V approx

thanks again 4 the help all!

[RaceDriver205]

Yeah, skyhigh, my motto is increasingly "shoot now ask questions later". Had a similar problem with the Maestro FSH having its FETs the wrong way round.