Help!! DIY phase 45 not phasing

[alfonso_bundis]

Hello everyone,

I bought and assembled a 45 phaser from Musikding, this is the schematic and the PCB:

http://diy.musikding.de/wp-content/uploads/2015/04/Phase45_schalt_errata.pdf

I think I did everything more or less correctly but when I test it I would only get clean sound from the guitar. The speed pot does not seem to affect the signal and the trimpot just changes the tone.

Here is a pic of the pcb's back:

http://i1175.photobucket.com/albums/r635/Alfonso_Crespo_Yapur/DSC_0197_zpsrkfx48rf.jpg
This are the Voltage readings

Power source 9.24V

T1
d   4.04V
s   4.04V
g   3.64V

T2
d   4.04V
s   4.04V
g   3.64V

IC1

1    4.05V
2    4.05V
3    3.85V
4    0.00V
5    4.04V
6    4.04V
7    4.04V
8    9.24V

IC1

1    4.05V
2    4.05V
3    4.04V
4    0.00V
5    4.60V
6    4.71V
7    4.87V
8    9.24V

the voltages of pins 5,6, and 7 from IC2 oscillate with an amplitude of  10 mV.

When tested with a probe pin 7 of IC" gives some oscillating noise.

what can I do to solve the problem?

Thanks in advance for the help.

[jimilee]

You've tried tuning the trimmer pot, and checked the pin outs on the transistors?reflowed everything?

[alfonso_bundis]

Yeap, I already tired those three things. Turning the trimmer pot just changes the tone. I tried inverting the transistor but still just clean sound.

[gtudoran]

If your trimmer changes the tone, then it means that the fets are working (because of the filter) what doesn't work is your LFO so check the parts around IC2B that should solve the problem.

Best regards,
DeX

[alfonso_bundis]

Thanks for the tips!! i will check it out over the weekend

[flanagan0718]

     Did you use 2n5952 or 2n5457. The doc says that the orientation of the 2n5952 is wrong. So if you used those (2n5952) then they would need to be 180 degrees of the screen print on the PCB. However, if you used the 2n5457 then you would need to orient them like the screen print on the board.

-Mike-

[Elijah-Baley]

Always check the pinout with the datasheets when we use different transistors.
And even when we used the stock transistor, because we never know.
Phase 45 is the first on my new building list.

Good luck!

[Marcvv]

You need to match the FETs. If not then you might get no phasing.

If you bought it as a kit I think Klaus will have send you a set of matched fets. If not then buy a set of matched fets or buy a whole bunch and sort them to find a matched set. I would suggest the first.
If you do have a matched set already then your problem might be elsewhere

[Elijah-Baley]

Yep.
Indeed I have just some FETs. I have to find the better couple.
I read that J201 could be help to have more effect.

I'm following this topic, if I can I'll help you. Keep going.

[alfonso_bundis]

Thanks to everyone for the replies.

     Did you use 2n5952 or 2n5457. The doc says that the orientation of the 2n5952 is wrong. So if you used those (2n5952) then they would need to be 180 degrees of the screen print on the PCB. However, if you used the 2n5457 then you would need to orient them like the screen print on the board.

-Mike-

I used 2n5952 that came with the kit I bought from musikding, so they are supposed to matched. will maybe try to get some other Jfets

[flanagan0718]

Right I'm sure they are matched then. Just take a close look at the doc. It said that the print on the pcb is wrong. Just make sure you put them in the right way.

[alfonso_bundis]

I tired placing the transistors as stated in the document and also in the direction shown on the PCb. in both cases I get only clean signal.
Made some test whit the sound probe. When I use it on the elements of the LFO, IC2b, R20 to R25, I get some oscillating noise that changes its frequency according to the potentiomiter, but there is no guitar signal. All the solfering seems to be ok. Is there something else I can try?

[Kipper4]

i dont think the  audio passes through  the lfo. you wont get an audio signal there with a probe.

[alfonso_bundis]

i dont think the  audio passes through  the lfo. you wont get an audio signal there with a probe.

Thanks, i am really new to this and this is just my second time trouble shooting.

[duck_arse]

alfonso - can you measure the voltage on the trimmer pot at R19, and rotate that pot from one end to the other? what is the voltage at each end of travel?

check the value of R25 with your meter (and no circuit power!). and can we have some photos of the top of your build, please?

[alfonso_bundis]

alfonso - can you measure the voltage on the trimmer pot at R19, and rotate that pot from one end to the other? what is the voltage at each end of travel?

check the value of R25 with your meter (and no circuit power!). and can we have some photos of the top of your build, please?

Sure. The voltage on the trimmer pot at R19 is 4.04 V at one end of the rotation range and 0.001 V at the other.
The value of R25 is 0.760 M, which is odd since its color bands indicate a 3M9 value.

Here are the photos of the board:




Thanks again for the help.

Thanks again for the help.

[duck_arse]

well, that's me out of ideas. sorry.

[slacker]

From your voltages it looks like the LFO, pins 5, 6 and 7 of IC2 isn't working. If you measure the Voltage on pin 7 of IC2 it should change back and forth between nearly 9 volts and nearly 0 Volts, the speed should be controlled by the speed pot. Does it do this?

[Marcvv]

And maybe post a pic of the solder side too please.

[alfonso_bundis]

well, that's me out of ideas. sorry.

Thanks anyhow dude.

From your voltages it looks like the LFO, pins 5, 6 and 7 of IC2 isn't working. If you measure the Voltage on pin 7 of IC2 it should change back and forth between nearly 9 volts and nearly 0 Volts, the speed should be controlled by the speed pot. Does it do this?

I got a better multimeter and checked the voltages again.
Pin 7 oscillated between 8.6 and 1.3 V
Pin 6 oscillated between 5.7 and 3.9 V
Pin 5 oscillated between 5.9 and 3.5 V
THe voltage of pin7 seems to be responsive to the potentiomiter, when I turn it fully clockwise it oscillates too fast to get a clear value

The voltages of the other pins are the same I reported before.
The voltages of T1 and T2 are:
T1

D  4.03V
S  4.04V
G  0.86V when the potentiometer is fully turned clockwise. With the potentiometer fully to the left it oscillates between 0.67 and 1.00 V

T2

D   4.04V
S   4.05V
G   0.86V when the potentiometer is fully turned clockwise. With the potentiometer fully to the left it oscillates between 0.67 and 1.00 V

And maybe post a pic of the solder side too please.

thanks again for all the help