Sabrotone Wampler Paisley Drive Build trouble shooting

[Misterwinefine]

Good Afternoon, first have to say this is an excellent site to learn and work through fx builds  Thank you all for your input.  I have built the Wampler Paisley Drive ( Aka W****** Daisley Prive from Sabrotone, and I am in Need a little advice, have the pedal working all the various controls work well.  I get a static when I have the Mid Switch flipped to either position.  In the middle it fine, And when I switch I do get a pop in either direction.  The Jfet voltages on Q1 are
D= 8.97
S=3.37
G=3.06

Q2
D=8.97
S=4.49
G=4.36
I have replaced the J201 trying to get a better match with not much luck.

I am stumped on trying to figure out what the issue is. I have double checked all the connections checked the component values, and checked cuts and jumpers.  All look in order.  Any suggestions?

[duck_arse]

two things we always like are circuit diagrams of what we're working on, and pictures of what you've built. and saying welcome to the forum.

three. the three things we always like .....

[bluebunny]

What have the Romans ever done for us?   

[Misterwinefine]

Sorry about not sending the proper doc.  http://www.sabrotone.com/wp-content/uploads/2012/11/PaisleyDrive.gif

http://www.sabrotone.com/wp-content/uploads/2012/11/PaisleyDrive_0_1_schematic.png

i was not sure how to paste the image into the Reply , hence the address above.  Hope this helps

[bluebunny]

i was not sure how to paste the image into the Reply , hence the address above.  Hope this helps

Click the icon.  Then insert your URL in between the [img] and [/img] tags.

[Misterwinefine]

Here is the schematic,  Sorry about the size.


And here is the vero layout

[duck_arse]

Good Afternoon,  I get a static when I have the Mid Switch flipped to either position.  In the middle it fine, And when I switch I do get a pop in either direction.  The Jfet voltages on Q1 are
D= 8.97
S=3.37
G=3.06

Q2
D=8.97
S=4.49
G=4.36

well, although you've shown us the vero layout, and not what you've built (the actually parts on the actual piece of actual vero that is causing the problems, like bad switch wiring), we'll let you off for first offence.

the 2 fets are wired as source followers, they are there to provide buffering for the guitar input and the volume pot. they load what comes before them with their 511k, and provide drive to what follows them. in this config, your voltages look right.

how does the presence switch affect operation? can we see the wiring of the 2 switches? what does the "static" sound like?

[Misterwinefine]

Thank you for the pardon on the first offense.  The noise or static I am referring to is a intermittent static not long in duration but on and off.  And it can get a bit high in volume at times.  And if the mid switch is in the center position it is less.  The switch for the Mid is a On-ON-On type.



The Presence switch is On- On



I checked all the guitar cables and double checked the connections as well.  All seem to be in order,  I have not changed the switch I can do that to see if this changes the outcome.

[duck_arse]

The switch for the Mid is a On-ON-On type.

I do mean to be picky. is this switch marked on-on-on on the body of, or is it marked on-off-on? on-on-on switches have some tricky pinout, different to ordinary centre-off types.

[Misterwinefine]

No worries about being picky, I understand the devil is the details.   It is marked On - On- On ,  located on the side of the body.

[duck_arse]

that will be the problem then. this switch has come up before, in a madbean deadringer thread.



it confused me then, it confuses me now. you'll have to check if right or wrong, maybe ..... no, the more I look, the more I confuse. it's meter time.

[Misterwinefine]

I will change this to a On-OFF-On and see if that fixes it,  and report back.  What you sent is a bit more confusing than a switch should be!

Thank you for your help.

[Misterwinefine]

That made an improvement, by changing the switch to the on-off-on,  I still have the pop when switched, and a lower volume level of static. 
How do you post a recording of the static and that may help identify where to look, it does not appear to be a ground issue, and I get the same level of static with a 9 volt battery or a bench power supply.  I do thank you for your expertise and time.




I will try a Dropbox post of the recording of the static!
https://www.dropbox.com/s/1eonlzci6357ypm/static%20noise.aiff

[duck_arse]

I got your sound file, but my linux box is driving me bonkers on many fronts, sound is one of them. I couldn't make the aiff format play, with volume. on that switch, it is an odd part to specify as on-on-on, because it is wired so the middle position is off.

was this board tested outta the box, or not till it went inside?

[Misterwinefine]

Both out of box and in same result , I can convert the sound file to mp3

[duck_arse]

argh, linux. I got a converter prog, and converted to wav. THEN I needed to get a simple player. THEN I needed to update the player, because it wouldn't play wavs. no it plays wavs, but it's volume control has dissappeared. oh, well.

so I've heard it. I'm not entirely sure I understand it, though. I'll have a few more listens. with the mid switch at centre, none of the filter parts are connected. this should be your base sound, your starting point. the presence in either position will not affect the tone with the mids at centre. is this what's happening? I can't get much information from your board photo, but you should get your meter and confirm the connections to C6 and R12//C7. also extra double check the ground wire of the mid switch is connected to ground. meter from switch to input jack sleeve, to make sure .....

[Misterwinefine]

The mid switch works in all three positions, center is unfiltered, and up is darker , down is brighter. All connections on C6 , R12, and C7 are solid.  The Ground connections are good. 

I have a suspect that mat be in question C7 is 470nf, when you flip the switch in that position for the connection you get a pop.  I have mounted the circut in a fixture to hold things so nothing is moving and it has been quite and working.  When you first power it up you get the static, and then it quites down. It is very intermittent at this point.

The gain pot is also a bit scratchy when turned , it also could be suspect?  That C 7 cap is a different variety than the others from Tayda? Code is 474 which is 470nf.  The Jfets are 201,s which I have heard are all over the board also from Tayda could they be suspect?

Thanks for your effort!  I think we are close because it is a bit more stable now than before! 

[duck_arse]

can you measure and post your voltages on the ic? the j201's should be a-ok if you can find some settings that produce relatively clean output, they aren't providing any gain in this circuit.

[Gus]

Is that schematic correct ?

Input JFET with a 511K gate to 1/2vref and a 1meg input antipop?

You could use a high beta hfe NPN for the same thing you could even increase the input antipop resistor value

TWO 1/2 supply Vrefs? could use two 4.7Ks and a 470uf for the same thing
OR use one for 1/2 supply for the opamps and another for > than the VBE drop above 1/2 supply for the emitter followers for more symmetrical drive

Output stage again a JFET and a 511K why use a JFET when resistor values are in this range?

[Misterwinefine]

so the IC readings are  IC is a 4580D  JRC

1, 4.437        8,  8.909
2, 4.437        7,  4.106
3, 4.437        6,  4.106
4, .0012        5,  4.108