help debugging Man 0' War, bad IC? voltages seem high.

[madbean]

I'm going to do a new build on the current batch of boards I have. I've looked them over this morning and do not see any trace errors. But, it's no big deal to re-verify in case something is amiss. I'll recheck against my recorded voltages and see if anything is up. I'll report back very soon so hang on just a bit.

[half_smith]

Thanks Brian! I hate to put you through extra work, it will probably turn out to be something stupid on my part.

However, if you can update the build doc for the MOW (not DX) with the voltages, that page appears to be cut off on the bottom.

*update*
The signal is clean going into pin7 of 1st 3005, the bias1 trimmer directly adjusts the voltage there.
The sound on pins3,4 (1st 3005) is helicopter noise only and changes speed with bias1 trim

pin2 (1st 3005) is very weak on both 3005 and 3101 - this is where I'm focusing my attention rn.
I think I might have killed the other 3101, I swapped them places to see if that did anything and I had 0v on pin2, swapped back and got 0.3v, at least something...

Q2, Q3 voltages look good
-that's as far as I've gone, signal hitting pin7 of 2nd 3005 is same helicopter as output of 1st 3005

Thanks for any further help!
I am determined to get this pedal working!

[madbean]

I'll get the voltages thing fixed up in the doc. Somehow that escaped me. Anyway, I'll be making a recording of voltages on the second build just for cross reference. I think I should be done sometime tomorrow morning.

[Zerro]

When I observe those pcb snaps, I wonder, why you don't use the rosin while welding? I noticed it at the most of snaps of many builders here. Without sufficient rosin amount is no reliable welding. Try to add it while re-welding all points, and if you had to weld some points several times, because of lack of proper contact (no wonder), try if that pcb track is not already burned and cracked off. That's a basic thing. Then you can solve anything else.

Most of tin-tubes for welding of course contain inside some kind of rosin. But it mostly isn't enough.

[madbean]

Okay got my second build going and it's working just right. So, that's a relief. I'm going to get the final calibration done, make a record of the new voltages then I'll come back and we'll see about solving your problem.

One thing I remembered during this process is you do need to have IC6 (MN3101) installed to calibrate the bias of the first BBD. This isn't explicitly stated in the build doc, where I instead said "remove IC5 first" when you being calibration of IC3. So, that's something I will add to the doc: it should have been more clear.

Could only find one XVIVE chip so I put two MN3005 in this one.

[half_smith]

Thank you Brian! Your build looks perfect, I'm jealous.

[madbean]

Here's the new list of voltages taken from the second build. They seem to be very consistent. The ones in yellow will be different for every build since those come from calibration (in fact I need to go back and take another pass at the bias for IC3 since it looks low).

So, based on this I don't see any issue with the boards. I decided to build the second one since my verification build was done on my original prototype from 2013. The production board is basically the same PCB just made prettier with minor layout adjustments. But, never hurts to be sure. Doesn't preclude the possibility of a single PCB having an issue but in my experience that's very rare. Generally you see several from the same panel have the same fault (like a microtrace connected between pads that shouldn't be there). Anyway, let's go with the assumption that the board was okay for now.

Looking at your reported voltages I'm seeing a lot of problems and some don't make much sense.  Some of your transistor readings are nearly at DC (by that I mean close to the power supply level) across all pins. That indicates (1) some very defective parts (2) some suspect soldering or (3) the voltages were taken incorrectly. I think it might be the last one. Your soldering looks pretty good so I'm not concerned with it.

Your emitter readings are consistently DC where your collector and base readings are lower. Your base and emitter readings on Q1 appear transposed. Q2-Q4 are all completely off. The pin7 of the 571 is concerning. I don't know how that could be possible. Even with a faulty solder joint that pin is in an area not even physically close to the power supply traces so such a high reading is another reason I suspect some voltages may have been taken incorrectly. But, I think we can figure that out.

Also, the use of inappropriately sized parts is something that doesn't necessarily make for a bad build but it can make it a frustrating one especially when things go wrong. I'm not saying people shouldn't use what they have or can get because sometimes that's the only option. It's very cool to use some mojo. But, a bit of a headache inducer when you do that for something as complicated as an analog delay instead of fuzz or overdrive.

Anyway, that's a lot of preamble. And, it's not intended to be criticism. Just observation and hopefully a little bit of helpful guidance.

-----------------------------------

With that out of the way let's see what we can figure out. Hopefully we are still at a point this is salvageable. Before we even deal with the actual delay portion of the circuit we need to take another look at some of the transistors. Here are the first steps I suggest:

- Unload IC2 - IC6. Let's go through process of elimination so we are not even worried about the delay part now.

- Measure the voltage readings of pins 2,3 and 7 of where the 571 goes. Just read it right from the socket. You will likely have some readings in the mV region. For example, on mine I had about 68mV for pins 2 and 3 and about 230mV for pin7. What we are looking for here is if you get a very high reading in the V range instead of mV. That might indicate a problem area.

- If that goes okay, disconnect power, and re-insert the 571. Reconnect power. Now check pins 2, 3 and 7 again and compare to my lists. We'll also need the 571 in place to take proper readings of Q2.

- Now re-take the readings on Q1 - Q4 and compare to the two lists I have. It's not drawn on the board but for almost all my transistor parts the square pad is collector (or drain for JFETS). Certainly they are here. All the collectors for Q1 - Q4 should read at the supply which in your case is 11.85v. Base will be lower and emitter lower still. Make sure you have a solid ground connection on your DMM's black lead, too (maybe clip it to the dc jack ground if you can, whatever is convenient). It's really easy to get a wrong reading.


Let's start from there and build out. If we can eliminate these issues in order I think we'll have something. Also, sorry for the missing voltage readings in the doc. I will correct those later on. I just completely missed it because I have little attention to detail sometimes!

[madbean]

Also, try taking the transistor voltage readings from the bottom of the pcb. This usually ends up being easier.

[half_smith]

Thank you again, and I really appreciate your help. I was struggling for a week or so.
I appreciate your fixes on the Documents, I did have both 3101's in while attempting to bias.
One thing I might still have wrong, I have my LED's and Pots all wired to the board, I see that your voltages are taken with "no bypass LEDs active" Could there be something happening with the way I have my test build (rock it before you box it) setup?

For clarification on where things stand currently:
The voltages I first posted were truly weird - then I discovered the disconnect between R18 and pin7 of my compander. Once I jumpered that connection the voltages (on the early part of the circuit) mostly came in line with the build docs.
The signal is loud and clear through the NE570 and Q2 and into 1st 3005 (pin7), but output on pin3,4 of 3005 is only helicopter (does react to bias1 trim), everything downstream from there is same helicopter.

Low voltage on pin2 of the 1st 3005/3101, and Q5, Q6 look way low (see next post for current voltages).
Not seeing any reaction on pin2 from any trim pots.

Clearly there's a disconnect or bad chip somewhere in that area. Any idea where to look?

I will continue to scour the board for bridges or bad solders, checking continuity between every component as I go.


Thanks gang, Brian, I am actually enjoying learning through this nightmare, but I do hope it ends!

[half_smith]

The voltages as they are now:

[madbean]

Ahh, great. I didn't realize that some of this had already been sorted. So, the good news is I think we know where to go from here. The problem appears to be in the clock itself. There might be another issue with the MN3005 output but let's figure the clock out first. Your voltages on Q5-Q7 are the start of the problem. Below are your voltages as compared to my newest set. Some of the voltages do vary slightly of the turn of the Delay pot (for reference I took these with Delay at max) but your readings are way way off.

----the boring stuff----
The clocks (MN3101) are controlled by an oscillator which is set externally via resistors and capacitors. It reads that oscillator, does some transformations then outputs a 2-phase clock that is read by the BBD which tells it how quickly to pass the audio signal through all its internal transistors (so, the delay time). But, we don't want a fixed delay time b/c that's not useful. We want to vary the clock in a precise way so that the delay time can be controlled. And that's what all that stuff between R45 up to pins 5 and 7 of IC6 (MN3101) is doing. The MOW is more complicated in its clock manipulation than say, a DM-2 or even the DMM, and it also uses a master/slave configuration (excuse the terminology for anyone who objects to that type of description). IC6 (master) sends out the read oscillator frequency to IC4 (slave) so it duplicates the same 2-phase output to drive its BBD (IC3). All this is to point out that a failure along any point in that sequence has a downstream effect which is why we are seeing a completely wrong voltage on IC4 pin2. It's most likely originating either at the delay pot or soon after.

Here's a much more precise and learned version of what I am describing: https://www.diystompboxes.com/smfforum/index.php?topic=99316.0

---what to do---
The places we need to check are
(1) junction of R45/D3 (you should be reading around 8v)
(2) delay wiper (middle lug). At CCW you should also read about 8v. At CW you should have a couple hundred mV.
(3) R47 - this is connected to Q5 CB which you are reading way low. But, check the other side of R47. You should be getting 11.83v there.
(4) Q7 E is connected directly to VC, but you are reading 5.54v. So that's definitely a problem.

I've attached another image that might be helpful (traces diagram). Everything connected to the fat red trace should read VC which is 11.83v for you. The green highlighted pads should all read about 8v. Use this as a guide as well. If you are not getting the correct readings in either of those then I suggest using the continuity checker on your multimeter to make sure they are physically connected. For instance check that R29 has continuity with Q7 emitter, or R53 or even pin1 of IC5. Do continuity checks with the circuit un-powered.

[half_smith]

Thank you for this treasure map. I needed the explanation of the MN3101s to follow the interactions, that helps a lot.

I found that Q6 was OL between B, C legs, I replaced it and immediately got about half way home.
I have about 2v (up from .2) on pin2 on IC3 IC4 and there is audible signal (with repeats) coming out of the 3005s! That is a big relief,
but should be 5.5v

However, the signal is muffled and there's a pretty big 120hz hum.

A few voltages are still lower than they should be (and a few higher), but I'm starting to believe.

I've tested continuity everywhere, and measured the resistors in place...
Maybe next I need to swap some of the capacitors?

Here's an update on my voltages, if that might help narrow down where else to look.

*maybe unrelated to the bigger issue here, but I noticed that Q1 has a lower Voltage on B than E pin (see attachment), that should never be the case right?

[half_smith]

Hey guys, thanks for sticking with me!
I have literally replaced most of the components and tried socketing various resistors to help bias, not really helped.

I got another MN3101 today, (finally arrived from DIYGUITARPARTS.AU), popped it into IC4 position and now my Voltages are much better all around, not perfect but nothing really weird.
So far my issues have been a bad Transistor and a bad clock IC... ugh, how many hours of looking at solders and values to no avail...

The problem now, the signal out of IC3 (pins 3, 4) has a high pitched squeel and no repeats?
I can almost tune the squeel out with the bias trim and clock trim, but the repeats are nowhere to be found.
The pedal line out has a relatively clean sound, no repeats :/

Any clue what to look at next?

Thanks again! Future generations will remember your service!

[jimilee]

You're a better man than me, I totally would've started over by now. Nicely done.


Sent from my iPhone using Tapatalk

[half_smith]

Haha thanks Jimilee.

I don't know how, but I think I have it working! I just swapped out the ICs again, different NE570, different 3101, different places, and started fiddling the trims by instinct... the probe inside the circuit is whiny, noisey, or no delay, but the OUTPUT SOUNDS GOOD.
I'm going to mess with it a little more, but I think it might be ready to go in the box. holy cow what a journey.
I'll report back, or share my Build Report in the next couple days.
Thanks for the support and guidance