Messages

Basically, if I run an audio probe through the circuit, I get audio passing. Once I get to the diodes and Q1 (which is currently a 2n5457), I lose audio output. Nothing past that seems to work correctly.

So far, I can get the frequency range correct (per Mooseapotamus and his great videos). Past that, I'm really really stumped. I would check voltages against a list, but I haven't found a list (so far). I might chalk this one up to gremlins.

I posted a few more specifics here, and will get a voltage chant and pictures up (site + iPhone did not get along). I seem to be hitting a wall in passing audio around Q1. If I audio probe, I can hear some flanger sounds. If you have thoughts where to dig, I'm all ears.

https://www.madbeanpedals.com/forum/index.php?topic=35524.0

On another note: I am a debugging madman! Solved a big problem on one of the new projects today. Held me up for two days.
[/quote]

Brian, the big brain, am winning again. Now, he will release pcbs for no raisin!

And to think, I was going TO FINISH my backlog of projects this year.

Great work. Needs more brainz!

Cool faceplate and fun project.

It was a lot of fun. Great to put faces with names.

And I did figure out my Arduino dilemma - thanks ChatGPT!

I put my name down, but am about 50/50 to make it. My son is on a new baseball team out of Omaha and they have a get together that afternoon. So, good chance to meet new teammates but might put me home later than 6.

If the time works, I might pop in and say hello.

As LL Cool J once said, don't call it a comeback!

Good to see the GrindCustoms name in the forum..I remember seeing a few of your boards, etc. floating around in the world.

Pulled C9, which when empty, let the sequencer run correctly (although really really fast like I stated in the last post). I replaced C9 with a new 3u3F electrolytic and it completely stopped the sequencer. There no longer is any sequencing at all. None. I didn't mention that in the last post.

One interesting thing is that if I tap around with a meter probe I can get the LEDs to jump one step (although not perfect). If I short the Gate and Source of Q2 with the random switch on, I can get the sequencer to hop around a bit. Not perfectly, but it changes the LED that lights up.

Thirdly, when I plug in the OneSpot, two LEDs come on strong. Each time, it's a different pair. Sometimes, 4 turn on, but then back down to two. One will control both LED intensities, and the other will turn down to almost zero (just a bit of light comes through).

Voltages are weird.

UC1 -- All looks good except pin 1 which is at 1.36 and pin 3 which is at 2.5-3.1V
UC2 -- Still doesn't look quite right in places. Some are better than others
UC3 -- Lots of 9.45V (that's the voltage from the wall), especially on pin 1, 2, 4, 5, and 14 (UC3 power). Weird......

Q4 has at least 9.2 volts on each leg. That can't be right.

Well, I've made some progress. I have now got the Dig Dug running somewhat. The lights are now flashing in an almost random-ish pattern. It doesn't necessarily cycle straight through, but it's not always random.

Like the title says, it's like Speedy Gonzalez did one too many "speeding-up drugs" for waaaaay too many nights. The LEDs run fast - really fast! Hyperactive fast. The LED that replaces the vactrol is flashing in time with the LEDs, but at an extremely high rate of speed. I'm thinking there is some trouble with the voltage making things run really fast. Speed pot has no effect on the flashing.

It looks to me (using an online simulator of the circuit) that the 2n3904 is way too hot voltage-wise (collector and emitter are at almost 9.4V from a 9.45V source), along with pins 1 and 6 (almost 6V). I'm wondering if I have a bad resistor/wrong resistor somewhere, perhaps a bad capacitor or diode. Also, LED on pot 7/pot 2 (depends on how you are looking at the board - second to last one on the opposite side from the SPDT switch) does not flash, it holds steady.

Any ideas? I can't debug with an oscilloscope - don't have one. I'm getting closer to having it solved, but still having trouble. Thanks a million for all of the ideas.

Patrick

I probably should have stated that I still don't get any blinking in sequence or random -- they all stay on solid.

I'm thinking there is trouble in the TL072 area, as the voltages look really weird. 7.6V on pin 1 does not seem right. I'm wondering if I have bad diodes or bad 10k resistors. They all are the correct values, but something is off.

I'll double check on wiring (which I have) and check Q2. I pulled Q2. The LED that replaces the LDR is just an LED that is solid on with the DPDT at one setting and then off with the DPDT in the other position.


I will look at what you stated, so hopefully I'll find an answer soon.

Patrick

Bumping this up to the top with a couple updates. And a plea for a direction.

So far, I've made a few troubleshooting improvements.

1. I reversed all of the potentiometer board LEDs -- they were backward. Pot control is fine, and the 4/6/8 switch shuts a few LEDs (though I don't think it's the right ones - the 6 setting shuts off 8 and 8 but leaves 7 on....).

2. Bypass is working through the 3PDT. Big improvement there.

3. Sound is still farty when listened to through an amplifier.

4. Vactrol replaced with an LED. LED lights up with one setting of the DPDT, but it is shut off on the other setting. Hmmmm.... thought it should be on all the time.

5. Voltages haven't changed much. I'm now ironed down to looking at the CD4017 area -- something isn't right, I don't think.

If you have any ideas on where to go, please let me know. I'm still searching for an answer. Thanks in advance.

Patrick

Happy new CD4017B day! 

No changes to report. Voltages seem to be the same. EXCEPT:
1. The LED that replaced the Vactrol is not lighting up.
2. No voltage on pin 6 on IC1 (TL072 -- I changed it out.).
3.  I didn't feel the CD4017B heat up nor did I hear hissing, so that may be a good sign.

IC2 CD4017B
1- 1.501
2- 1.503
3- 1.46
4- 1.442
5- 0.067
6- 0.002
7- 1.512
8- 0.00
9- 0.001
10- 1.483
11- 0.002
12- 7.80
13- 0.00
14- 7.80
15- 3.65-3.90
16- 9.46

Probing around for voltages, I saw so weird things happening at the positive side of c14. Big fluctuations, even along the trace up to R28 and R27. Fluctuations for 2.5-3.6V. Pins 12 and 13 of IC3 (4093) is acting a bit weird also -- doing the same fluctuation. Any ideas on where to look? Transistors? BS170? New 4093?

Patrick

Thanks for the ideas stecykmi.

I forgot these in the rush to post the help before I fell asleep.

Q3 (bs170) -- This looks a bit weird to me.
D- 9.45v
G- 0.5v
S- 5.1v

Q4 (mpsa18)
C- 9.45v
B- 2-5v (I think it was fluctuating a bit)
E- 0 (at ground)

Q2 (bs170) -- these look wrong
D-  0.03v
G- 9.45v
S- 0.05v

Q1 (mpsa18 for the wah portion) looks good to me.

Maybe these numbers will help just a bit. Thanks everyone.

Patrick