HELP me Debug a cool Flanger

[FuzzAldrin]

I bought this for a cheap price knowing it didnt work.
Here is what it looks like:  http://www.modezero.com/nady-ps018.htm

It is a Nady MIJ (80's) Flanger. From what I have seen it is exactly like the guyatone series of pedals. I cant find anything with a google search. Built like a rock. Boss style switch.

Ok, with battery or PS connected, the LED does light up.
NO Bypass
When I turn it on, and with my amp cranked I can hear some oscillation and the knobs do affect the oscillation. I hear beautiful flange! Very thick, but it sounds very very "far away", so to speak. Until I cranked my amp I couldnt hear anything!

I opened up the case, and the pcb looks fine. Soldering looks very good (wave solder perhaps). Took my jewelers loupe and searched for cracks, or bad soldering but all looks fine. The PCB has connectors to it, so I can remove them and take the board without desoldering anything! Like a wah wah, basically.
Would love to get this to work! If anyone can help that would be great!
I will post some pics shortly.
I can see MN3102, MN3207, TL4558P x2 and a TL022CP CHIPS, if that interests you.
So, what the first step I can take to fix this?
Thanks to all who help, btw. 

[Ice-9]

Hi, From your description i would first check the bypass circuit is functioning correctly (if similar to boss then try trace the circuit)

I would imagine the op amps in these chips (TL4558P x2) will be the input buffer, filters and the output mixer so you could probe the signal at these chips.

The TL022 will be what is used for the oscilator to control the modulation of the clock signals as you can hear the flange sweep this part would seem to working ok.

[Mark Hammer]

If it uses a Boss-type flip-flop-plus-FET switching strategy, then it is also highly likely that it simply uses one JFET to connect/lift the wet signal to produce the effect.  If so, then you could simply tack on a wire jumper across that JFET on the copper side of the board to see if the problem originates in the wet/delay path, or the switching.  What you would be doing is turning the flanger effect on permanently (well, on in spite of what the footswitch does).  If the problem remains in spite of the jumper, then it is unrelated to the switching circuitry and you can simply remove the jumper.

[FuzzAldrin]

oh, it also has 3 onboard trimmers....
havent touched these yet. Should I bother?

Should I also just try using a new boss style switch? Been thinking about replacing that anyways, along with all the 'lytics...

[Mark Hammer]

One trimmer will likely be for setting the BBD bias.  One may be for setting the maximum regeneration prior to oscillation.  The third may be for fine-tuning the clock.  The first one will alter the amount of delay signal heard, but if faint it should also sound very distorted as well, which you have not reported.  The second is not likely the culprit since it has no effect on delay volume.  The third will change the quality of the flange effect but not necessarily the volume of it.  You can play with all three of them without fear of damaging the pedal, but make a point of marking their original settings.

My money is still on figuring out first whether the switching system has anything to do with it.  A number of folks in past have reported bad JFETs that made bypass or effect mode behave wonky.

[FuzzAldrin]

My money is still on figuring out first whether the switching system has anything to do with it.  A number of folks in past have reported bad JFETs that made bypass or effect mode behave wonky.

Thanks Mark. Im still a newb to all this. Can you explain how I can find the JFET? I dont even know what a JFET is, to be honest. Im guessing it is a transistor? Q1 maybe? the board has about 13 transistors, and they all have the same readout. They all seem to be  "C 1571 F 4A"
A google search returns nothing helpful. Pages for only "C1571". Not sure if these are right, but they appear to be NPN Bipolar IC's...
I am definately ordering a new Boss type switch for it.
I just bought an audio probe and multi meter. Should I hook it back up and get tranny readings? I also can not find a schematic at all. Ive emailed guyatone and nady, and nada so far.
Thanks.

[FuzzAldrin]

"JFET operation is like that of a garden hose. The flow of water through a hose can be controlled by squeezing it to reduce the cross section; the flow of electric charge through a JFET is controlled by constricting the current-carrying channel. The current depends also on the electric field between source and drain."

Is that why I can barely hear the effect when turned on? I mean, amp on 10, I can hear subtle flanging. No bypass...


BUMP!

[FuzzAldrin]

BUMP

Just need a push in the right troubleshooting direction.

[Mark Hammer]

Typical JFETs used for switching will often be 2SK30A or 2SK118 units.  The 2S will normally be dropped so that you see K30A on the transistor.

[FuzzAldrin]

Ok, I replaced the JFET. Still the same problem.

My power supply is pushing out 9.12v

My voltages for the IC's are:

IC-1  (TL4558P)
4.57v
4.57
4.57
0.5
4.57
4.56
4.56
9.12

IC2  (TL4558P)
4.52
4.55
4.53
0.00
4.54
4.55
4.53
9.12v

IC3  (MN3207)
O.00
2.64
3.16
5.05
5.44
2.50
3.54
3.59

IC4   (TL022CP)
Weird. My meter displays it climbing and dropping from 1.9 – 2.5v steadily.
2.73
2.73
0.3
Drops from 3.91v to 1.18 and back up (?)
2.73
0.62
5.46

IC5 MN3102
5.45
2.6
0.5
2.5
5.25
140MV CLIMBS...
4.34
5.08


Thats just the IC's. The trannies are not labeled E,B or C.
They have a couple letters on them, and google has nothing on them. No idea what they are.
A schematic is likely impossible. Ive tried that too.

[Thomeeque]

IC4   (TL022CP)
Weird. My meter displays it climbing and dropping from 1.9 – 2.5v steadily.

Man, that's not weird, that's LFO! 

Make some hi-res pictures of the board (both sides, more angles), that can help a lot (and can be useful for others as well)..

T.

[FuzzAldrin]

LFO, eh? Makes sense.

I dont know what good pictures will do honestly. Its not a kit or anything, but I will have to borrow a camera.

Like I said before, the trannies have strange numbers on them, besides the SK30A, and searching online brings no results. I have no idea what they are or what the EB or C is, thats why I didnt bother with the voltages for them, yet.

I have a probe thing, but I dont really understand what I am looking for, either.
I dont want to give up on this.

[Jered]

  Contact Nady
       http://www.nady.com/customer_service.html
  Maybe they can send you a schematic or you can send them the pedal for repair.

[FuzzAldrin]

already emailed them like I said. I just emailed them again, too so we will see.
Send it in for repair?? Not a chance in hell. There is no way I am paying round shipping AND parts and labor on something like this, when it is possible for me to do on my own. Basically I want to learn something...

[FuzzAldrin]

got an auto reply email this time. The guy is out of the office until the 26th, but gave an ext. to call.
Called the guy and he cant send me a schematic cause its "a proprietorship" ... and that if I ask the other guy when he comes back there is a slight chance I can get one, but it requires management clearance (I swear that is what he said), so I shouldnt hold my breath.

[Thomeeque]

LFO, eh? Makes sense.

I dont know what good pictures will do honestly. Its not a kit or anything, but I will have to borrow a camera.

Like I said before, the trannies have strange numbers on them, besides the SK30A, and searching online brings no results. I have no idea what they are or what the EB or C is, thats why I didnt bother with the voltages for them, yet.

I have a probe thing, but I dont really understand what I am looking for, either.
I dont want to give up on this.

Hey! Never give up! Never surrender!

Good pictures would give us chance to derive circuitry (when we don't have schematic). Plus I like to watch pedal gut-shots

Meanwhile lets try this:

• set RESONANCE to the min, MANUAL to the middle, and DEPTH and RATE to the max
• plug some signal to the input (preferably some kind which leaves your hands free, but if it's problem, just plug guitar there)
• now with probe listen to all TL4558P's outputs (pins 1 and 7)

This way you should be able to easily locate output of wet signal - this will be either: vibrato tone or already flanged (vibrato+dry) tone (it depends on exact topology of your effect). If you will find both, the flanged is interesting. Now you can trace path from this point and check, where it gets lost. Or you will not find such signal and it would probably mean problem of some of those op-amps.

Try and let us know..

Btw. it's bit strange, that IC1 has 0.5V on pin 4 (Vee), exact 0 I'd expect (direct connection to the ground). Check it again.. if it's not 0, problem might be there (no power to IC1 = no signal passing thru)!

[FuzzAldrin]

Thanks man.
I went back and its 0.5mV. The other 4558 chip is the same, but I just typed down 0.00 for some reason. All other readings are what I posted above.
On the back of the pcb it has 5v and some 9v by some of the soldered parts. I tested them with my multimeter and they get what they need. I cant hear anything using this probe thing. Just white noise. The TL022 has very fast clicks, though, thats about it.
Im still working on it... I probed the output and I do get a decently strong wet signal and I can manipulate it by turning the knobs. I can hear thick flange. some pins of the ICs now also have some flange sounds cause I have distortion on on my amp so I can hear better. This is as far as I got.

[cjlectronics]

Typically, there are two JFETs in a momentary switching circuit.  You stated in an earlier post that you replaced a JFET.  Did you replace just one JFET or two?

CJ

[FuzzAldrin]

Hi CJ, I replaced only one Jfet. The SK30A that Mark pointed out.