HELP WITH A CHUNK SYSTEMS AGENT 00 MARK II

[DOND]

anybody have any ideas on what I could be missing?? whatever it is has to be stupid.i have been through this thing 6 times...I am stumped

[DOND]

howdy to all-
   I have finally gotten a chance to take all voltage readings off all ic's/op amps.here are my voltages with all pots set at half way.
     LM13700-1=1.48      16=1.48                                                                   LM324N-1=3.47        14=4.94
                    2=1.12     15=1.06                                                                                 2=3.47       13=4.76
                    3=4.75     14=4.75                                                                                 3=3.42       12=4.76
                    4=4.75     13=4.75                                                                                 4=9.48       11=0
                    5=5.93     12=5.77                                                                                 5=4.53       10=4.76
                    6=0         11=9.48 (USING 9 VOLT ADAPTER)                                           6=4.76        9=4.76
                    7=5.93    10=5.17                                                                                  7=4.76        8=4.76
                    8=4.75    9=4.61                                                                       

                                                                           TL074-1=4.76       14=3.46
                                                                                     2=4.76       13=4.33
                                                                                     3=4.76       12=4.33
                                                                                     4=9.48       11=0
                                                                                     5=4.76       10=4.76
                                                                                     6=4.76        9=4.76
                                                                                     7=4.76        8=4.91

what do you guys think? any input is appreciated...............................

[DOND]

update....seems that all the chips/op amps are bad in this pedal.i over layed a 17300 chip and a tl074 chip and now am getting some activity out of this thing,don't have a lm324 so I ordered some,but after over laying the 17300 and tl074 chips I now have heat (both chips running around 120f) where as before they were at room temp...only thing I can figure is this pedal was hit with 18 volts.yet all voltages show ok (from what I am getting from reading on here and other sites)

[tonyharker]

You're still doing something wrong.  The chips should run cold. If they are hot then they are ruined.  You cannot as you say overlay one chip on another. Do you mean piggybacking one chip on top of another. This is a route to disaster and could ruin both chips! You also cannot diagnose a fault using just the chip voltages unless one is totally shot.  The signal should be traced through the circuit using a signal tracer. Checking at each stage. 
There are a lot of what appear to be plugs and socket connections on the schematic, these are places prone to bad solder joints. I would check these and any other connections made to components off the board.  If the Pots are soldered to the board then these joints should be remade.  If the chips are not socketed and you are replacing them I should put them in sockets.
Hav you photos of the guts of the pedal?  If so please post them so we can see what you are doing.

[DOND]

great...will post pics, tony.....wish I knew what I was doing wrong/missing.i thought I was actually beginning to get the hang of this.when I layed the chips over each other and actually got LED2 (assuming its the clipping diode) to work and some action out of the pots I was getting close,but you guys know better than me.will post the pics of everything as soon as I can...once again,thanks for the input

[DOND]

HAPPY BIRD' DAY GUYS!...as requested by tony I am attaching photos of what I am dealing with

[DOND]

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[DOND]

photo #107 IS THE TL074 CHIP
photo #108 is the 13700 chip
I have no activity out of the 324 chip
when checking voltages I am using the - (negative) pin of the 9 volt battery adapter plug
I seem to have all grounds and voltages,just this pedal will not work right.
after running out of ideas I decided to overlay the 13700/tl074 chips and I got activity (as seen with the thermal images).I get 0 activity from the 324 chip.
as tony stated the way I am doing this is totally incorrect and I get it.will redo it all correctly,but want to get it to work first....
I thank you all for all the input as I am getting educated slowly but surely!

[mcknib]

Schematic is here on my google drive you can download it and zoom in to make it nice and clear, looks like the whole circuit

https://drive.google.com/file/d/1-l4UnaDlq5tgom8pAV14rahZSgcwMVm4/view

[DOND]

hey guys,I am back because,i am too stubborn to leave it alone.i have gone through this again.got rid of my "piggy backed" chips.soldered in all new ones (naturally it still doesn't work right).when the up/down switch is in the "down" position,the pedal attempts to work (I can get some activity out of the pitch control(P1),squelch(P4) tries to do something,smoothness (P2) and sweep (P3) really don't do squat).if I use my finger and bridge P1 (pitch) terminals 2/3 with my finger tip,pedal actually begins to sound like the demo on chunks website/youtube video.when the up/down switch is in "up" the pedal sounds like I bypassed (turned it off) it.since all voltages seem to be correct,resistors seem to be ok,i decided to recheck the electrolytic caps and as a goof I decided to go from ground to the cap housings/tops,for all the caps for leakage I have from 112 mv to 260 mv EXCEPT for C2 WHICH IS SHOWING 3.38 volts...thought I had hit oil and had a leaking cap.replaced it and still have the same reading and issue......if I have learned anything.looking at the diagram C2 sets the bias voltage on the LM324N chip U3:C (not exactly sure what that means but I am assuming that is pin 10 on the chips datasheet (input 3,tracing it from the cap to the chip).here is where I am getting confused.the schematic shows the - side of C2 going to grd,yet on the grd side I have bias voltage and tracing it is going to R17,etc.so I am assuming that some of what I am seeing marked neg is actually going to be bias voltage and the voltage I am getting off C2 is normal..?

[DOND]

also.....now when I move "up/down" switch to down and bridge P1 (PITCH) PINS 1/2 I now can get the pedal to start to come alive....fwiw,i have checked the continuity of the ribbon cable that joins the potentiometer board to the main board for shorts/opens....they're all good...I know all I am doing by bridging the P1 pot is creating resistance to grd threw my body...so am I losing grd somewhere??

[tonyharker]

No all your'e doing is shorting the pot pins through your finger there is no actual ground. It looks like the pots are not making connection inside. I would say that the pots are probably dirty inside or failed,  try squirting de-oxit or similar into the pot bodies and turn the knobs back and forth a few times.  Also resolder the pot pins on the circuit board, you may have a number of dry solder joints.

TONY

[DOND]

thanks tony.....I did go and resolder all the terminals (as you suggested earlier).will try the contact cleaner,but fwiw when I check the pots with a meter,they show operational.will do the contact cleaner and report back....thx!

[ElectricDruid]

If I think I'm going to need to change chips, I like to fit IC sockets to enable easy replacement without risking further damage to the PCB. Makes life a lot easier.

You've posted voltages several times, but then rapidly changed things so that the voltages you posted are no longer valid for the circuit you're looking at. You need to slow down and back up. This thing can be fixed, but you're in danger of making it worse not better. The piggybacking chips idea is terrible, and I have no idea where you got that from but it wasn't a reliable source. As Tony said, all that is likely to do is fry the second chip as well as the first.

Let's get an audio probe and go through from the front. Do we have any idea which op-amp is which in the package? I notice the schematic doesn't show pin numbers. We'll have to *assume* that "A" is the first op-amp, "B" is the second, etc, but it's not a certainty.

Do you have audio at TL074 pin 1? (Output of the inverting input buffer U2A)
Do you have audio at LM13700 pin 8? (output of filter's first stage U1B)
Do you have audio at LM13700 pin 9? (output of filter's second stage U1D)
Do you have audio at TL074 pin 8? (Output of output buffer U2C) - (Answer to this is likely to be "No" because if you did it would be working).

At some point along that path, the audio stops. Where?

Now let's have a look at the envelope follower.

Do you have audio at TL074 pin 7? (Output of envelope follower input buffer U2B)
Can you see a changing voltage with a multimeter on LM324 pin 1 when you move Pot1 100K? (Output of envelope offset buffer U3A). What's the maximum voltage? What's the minimum voltage? Now switch the Up/Down switch to the other position and repeat the test. What are the max/min voltages in the other position?

That's plenty for starters.

HTH,
Tom

[DOND]

ElectricDruid...I agree.i am like shit through a fan with this.need to start from beginning again.on the "piggyback" idea...yea..bad idea (I listened to psycho..my fault).just recently learned about a audio probe(still learning how to navigate my way here)...going to make one over weekend.just not exactly sure how to use it but if I understand the process correctly,i run a signal threw the input (don't have a signal generator so I have to run a guitar into the input) and just use the probe side to bypass the output jack until I get sound/no sound....on op amps.my assumption is the same as yours..i thank you for pinouts.will post back....thx!

[DOND]

as per ED's directions....here is what I have on:TL074 PIN 1=AUDIO
                                                                     13700 PIN 8=AUDIO ( AUDIO WITH A HISS,ALMOST SOUNDS LIKE CRICKETS IN A FOREST)
                                                                     13700 PIN 9=AUDIO (AUDIO)
                                                                     TL074 PIN 8=AUDIO
                                                                     TL074 PIN 7=NO AUDIO.ASSUMING THIS IS PROBLEM OR AT LEAST PART OF IT
                                                                     
                                                          ON PIN 1 OF 324 CHIP,SWITCH DOWN..VOLTAGE LOW TO HIGH=3.25/4.64
                                                                                             SWITCH UP.......VOLTAGE LOW TO HIGH=2.70/4.23
fwiw,i had no "effect" when I did these tests but don't know if I was supposed to have the effect (don't think I am supposed to)

[DOND]

after doing the E.D, test and going back and looking at the diagram (without the chip pin #'s being identified) is it possible the 324 chip is my problem?

[ElectricDruid]

It's possible the 324 is a problem, but we've got another problem before we get to that.

If there's no audio output on Pin 7 of the TL074, then there's no signal going to the envelope follower. That'll make it impossible for any of the following stages to do anything, so we have no idea if the 324 is doing anything until we fix this.

First guess for why the buffer is getting no signal would be that the "Envelope" jack J3 is knackered and isn't passing the signal from the input buffer U2A correctly. A dirty or broken connection at this jack would kill the envelope follower.

You said we've got signal at TL074 pin 1, so the output of the input buffer U2A is ok. Can you get the same signal at the normally connection of the jack J3? Does it then appear at the other connection of the jack (the springy "lever" part of the jack) when no plug is inserted? Can you find C3 and find the signal there?

Good luck!

[DOND]

E.D...what am I exactly looking for? when I am doing the tests,the envelope jack is "open" (no input jack in  it).I thought about the envelope jack multiple times but can't find anything wrong with it but not exactly sure what I am supposed to be looking for either....yes,i know I sound like a moron,but I am new to this(but am learning quite a bit from you guys but enough to not sound like a dope).so I am not exactly sure on how to troubleshoot this...am I using the audio probe or volt meter? if the audio probe,exactly where am I going with it? if using a voltmeter,where and what am I looking for,same goes for C3.i know where it is but what signal am I looking for?
  I know...I sound like a moron

[DOND]

I just used the audio probe on the envelope jack.i get sound (no effect,but audio)..BUT if I use a tweezer to push the envelope jack lever down I DO get a signal out of pin 7 of the TL074...so its safe to assume the envelope jack has been kicking my dick in with this.so now with me holding down the lever on the envelope jack,i get audio when using the audio probe on tl074 pin 7 but still have no effect.is it possible the envelope jack and lm324 have both shit the bed?