HELP WITH A CHUNK SYSTEMS AGENT 00 MARK II

[ElectricDruid]

That sounds like progress.

Another way to test that would be (with the pedal powered off and unplugged) to put your meter on the "continuity beep" setting, and check across the legs of the jack to see if that jack lever is making contact. But it sounds like you're pretty clear it's not.

I'd start by replacing the jack. Once you've got a good solid audio signal at pin 7 (it should be louder than the signal at pin 1 - there's some gain on that buffer U2B) then we can work out what's going on with the envelope follower and the LM324.

[roseblood11]

The original pdf has all the values. If you PM me your email I'll send it.  The system will not let me post pdfs

Two options :
a) change the file extension to .txt
b) open the pdf file in Gimp and save it as gif or whatever

[DOND]

E.D.,i already ordered the jacks from small bear electronics,(ordered 2 different ones,though I think the Russian trs is the right one),for time being I am just bridging the jack with a paperclip.fwiw,i have a 324 chip.should I just replace the current one with a new one and see what happens?
  I also would like to thank you and tony for all the input and education.i assumed like a ass that if the envelope jack wasn't being used that whole part of the circuit wasn't used.well...I will now go graze with the other jack asses.

[ElectricDruid]

Unless the LM324 is socketed, I'd leave it where it is for the time being. If it's socketed, it's an easy test, so you might as well try it. But if not, it's a load of fiddly desoldering and you risk pulling up tracks. So I wouldn't bother unless we have to.

WRT the envelope jack - yeah, in this circuit the audio signal is "normalled" through the jack when nothing is inserted. But it just depends on the circuit, so you don't know until you check the schematic.

[DOND]

LMAO...no sockets..that's when someone said "just lay the chips on top of each other" nonsense....and I already know that ain't it.i just checked the circuit from PIN 7 of TL074 to,if I am right,PIN 14 (U3D) of the 324 chip and I had like 1meg,which would be about right with the 470k(r25),220k (r24)and 10k (r15) in series plus whatever resistance is coming from the 100k pots,so I know nothing is open circuited or shorted ..if it comes to a possible 324 chip,i would have to solder wick it out (that I have also learned after the whole "ARE YOU OFF YOUR BIRD" STACKING CHIPS,so I learned how to use solder wick)..it's also the only original chip left in this thing so if you suggest changing it,i will....

[ElectricDruid]

Ok, let's have a look and see what we can test going through that envelope follower.

We've got signal at U2B/TL074 Pin 7 output now, right? Thanks to your paperclip. All good.

From there, it goes to the precision half-wave rectifier based around U3D/LM324. There should be audio at pin 14, but since it's had half its peaks chopped off by the diodes, we're expecting a full-on fuzz sound, *not* any sort of clean guitar signal.

After that, there's an RC filter based on P2/R34 and C2. The passive filter is buffered by U3C. The output of that should be getting close to our envelope signal, so at pin 8, you should be able to see a voltage (so multimeter, not audio probe). The voltage should respond to playing. If it doesn't change between "no signal" and "playing hard" then something's up.

Incidentally, by that point we've passed two pots that are connected to the rest of the circuit by a ribbon cable. How does the cable look? Have you connected it and reconnected it a few times? (that often helps clear corrosion from the pins). How do the sockets look?
We might have a electronic problem, but mechanical failures are more common in my experience (knackered pots, dead jacks, dead power sockets, broken wires, etc etc) so let's try and rule that out too.

[DOND]

E.D....using the audio probe I have full blown distortion though as soon as I touch pin 14 of 324 chip it's like standing in front of a marshall turned all the way up with hot pickups.major feedback and also sounds like eggs frying (could be dirty voltage I guess I am using a 9vlt adapter)but when I hit the bass strings I have major distortion.on pin 8 (while using the probe on pin 14) and beating the bass strings light or hard voltage on 8 stays at 4.74 volts..no change.also moving up/down switch makes no difference on pin 8 either.still sits at 4.74 volts...chip toast?

[DOND]

sorry.looked at wrong pin voltage for pin 8. pin 8 is locked at 8.25 volts.not 4.74..sorry for bad info on that one

[DOND]

on the ribbon cable.i have checked continuity of all the wires,no breaks,shorts,i have done pin drag tests,all seem snug.ribbon cable is wires with 2 squeeze connectors (1 on each end,in diagram marked J5/J6),that basically must pierce the wires.tried to take it apart but they don't come apart all that easy.also no markings on them to identify what terminals are what (1/2/3/4 etc)

[ElectricDruid]

No, don't take the ribbon cable apart! Those IDC ("insulation displacement connector") plugs are generally pretty reliable if done right, and if there's a problem it'll be muck on the pins/tarnished or caught up inside the plug.

Pin 14 sounds good - plenty of level and massive distortion, just like we were expecting.

Pin 8 doesn't sound so good. Do you get any voltage change at pin 10 (the +ve input)? That's the unbuffered voltage, so if that's ok and changes, but the output at pin 8 doesn't then the chip *is* at fault. If pin 10 doesn't change either, then perhaps the 4u7 cap is faulty.

[DOND]

I hear you and I am learning here...I haven't done the pin 10 check,but I thought about the 4u7 cap.replaced both the cap (old one checked ok when I tested it out of circuit but put a new one in anyway) and I put a new 324 chip in also since I was desoldering/soldering.still no voltage change at pin 8.will check pin 10 and get back here in a minute

[DOND]

performed check with new cap/chip my voltages on pins 8/10 mirror each other.only difference is my voltage is now 3 volts on both pins.when hitting strings, voltages do not change.they both sit at 3vlts.fwiw,i have gone over all my solder connections from chip/capacitor legs to all the destinations and have continuity throughout......this pedal is possessed

[ElectricDruid]

Hey, stop changing things! How are we supposed to debug a moving target?!

Do you still have plenty of distorted audio on pin 14 of your new LM324?

[DOND]

my apologies.....on changing stuff......I know when checking components it's supposed to be out of circuit,when I removed C2 to check it (and it was good) i put the new one in for ha ha's and the chip for peice of mind...on pin 14...oh yea,,,it's a train  wreck.as soon as I touch it with the probe..feedback,and when I hit strings,loads of distortion...also I am making sure I am doing all required tests with all pots at mid (half way) so I don't end up chasing my ass from varying voltages by turning pots.so they all are now staying midway

[DOND]

morning!...I am going to punish myself some more with this pedal.will replace my faulty envelope jack today and re-evaluate all my chip voltages and retest with the audio probe.when we left off I was not getting any varying voltages on pins 8/10 of the 324 chip .question....I am assuming I am checking this with my multimeter on DC voltage (voltage was 3 volts solid)and voltage did not change when hitting strings.assuming all is correct in my diagnostic path (I am sure it is,as ELECTRICDRUID took the time out to guide me),what would my next step be in my diag as to why there is no voltage changes on pins 8/10 of the 324 chip?

[DOND]

ok,i have changed my trs jacks (envelope and I noticed the output jack levers were also flakey,so I changed that one also).redid my audio probe tests and have the same results on pins 8/10 of the LM324 chip.i noticed with the pedal plugged in no input jack I have 9 vlts on 8 and roughly 8.50 on pin 10 (which I would expect to be normal since I don't have any input),when I plug in a input,my voltage gets cut in half on both pins 8/10 (like it should),but if I hold my voltmeter lead on pin 8,my voltage slowly increases (I stopped at 5.67 vlts) and on pin 10 my voltage decreases (I stopped monitoring it when it dropped off at 2.97 volts)..I would assume if I plugged a input in (I used the 1/4" end I cut off a cable to make my audio probe) and was idle my voltage on those 2 pins should stay at 4.50/5.00 volts...It's like I am charging on pin 8 and discharging on 10..pin 8 is an output and 10 is a positive input....with the diagram not being labeled pin wise I am not sure on who/what is doing what perse...
   I don't know if I am on to something or not...hoping one of you guys can help me with this one...I will say thanks to tony and ED I did manage to get rid of a lot of issues.no more radio frequency pickups,etc but this thing is still will not work.using the audio probe on pin 14 of  have a shit load of distortion so all is good to that point,just no voltage changes on pins 8/10...if I check my voltages I get the same result I described with just using the input plugged in.....capacitors???

[DOND]

well back on this project again...newest observation (other than it still not working correctly)...without using the audio probe and running the pedal ouput to the amp,the up/down switch in the up position and when ONLY using my voltmeter + lead (for ground I am using the negative lead hooked up to the battery negative terminal),if I check for voltage at terminal 10 of lm324 my voltage instantly starts to drop from 4.50 volts to 3.80 and starts to rise back to near 4.50 and begins to go back down and than rise again.this is with no influence from the guitar strings.when I hit the strings I get low/muffled distortion .if I remove the voltmeter lead,it will stay low/distorted until I start hitting strings or I just let it sit for a bit and.the volume will begin to rise and I get a slight hint of what the pedal should actually do than it gets to point where volume is normal and as if the pedal is bypass mode.performing same test on pin 8 doesn't change anything.i reperformed the test with a toothpick on pin 10 and it still sounds like I am in bypass.only when I use my voltmeter on pin 10 do I get some sort of excitement out of this POS,but it's not making sense to me.best way I can describe what I am getting is as soon as I put my positive lead on pin 10 of 324 it begins to sound like the intro to "moving in stereo" by the cars (sounds stupid but that's what I get).like I said I redid this experiment with a toothpick and a plastic pick I use on amps,and nothing changes so it isn't a connection issue.with switch in down position it really doesn't make a difference with my voltmeter lead on pin 10.....if I do this on pin 8 of 324 it doesn't change anything.....
    does this make any type of sense to anyone?? sure as hell isn't making any sense to me.almost ready to check into rehab with this shitten thing...was easier to figure out what when bad in my egnater head.......
        E.D.....does this make any type of sense to you???

[DOND]

I am back for more punishment...now after going back,re-reading and retesting,i have found that my P2 pot has 3 dead spots (my ohm readings go to open circuits).both tony and electricdruid both mentioned pots that are/can be suspected and I did see on the schematic that P2 affects pin 8 of LM324.my question is can a bad pot keep this pedal (or any pedal for that matter) from working at all? I did order new pots from small bear but wondering if I am just going to replace the pot to still be up shits creek?

[DOND]

well,after all my dumb questions,i would like to thank Tony (for the schematic and input)and ELECTRICDRUID (for the time in educating me on the audio probe and on how to diag/read the schematic logically on a pedal circuit from input to output and figure out what does what).after my complete shit show with the chip stacking (what a bad idea that was) in the end this pedal had 2 problems.the envelope TRS jack and 2 of the 4 pots had flat spots.i also learned that it is no joke about testing components in circuit and out of circuit.in circuit is a good way to chase your ass...out of circuit is really the only way to make sure the component your testing is legit or not.
   my pots were delivered today.replaced P2 and P3 (also replaced P1/P4 so the knobs were all the same) and the pedal is up and running,and the answer to my one of my 911 posts is,yes,the bad P2 pot kept my voltages from changing on pins 8/10 of the LM324 chip.
     anyway,TONY and E.D.,i thank you both very much.you both taught me a great deal

[tonyharker]

No worries mate glad to help.  Have a Merry Christmas.