MS3 Board Troubleshooting (Q14 & Other Issues)

[MooPlusMoo]

Hello all!

I was given a built V3.0 main board, with an MS3 CPU card and MS3X expansion card. It was built by a close friend with some good soldering skills, but he handed it off to me after having some problems getting the finished ECU to communicate with a PC.

I just disassembled it on the bench, and it looks well put together, with a couple of issues that immediately jumped out at me:

-Chip U7 was relocated to the Proto Area. He said he swapped U4 and U7 accidentally, and had a tough time removing solder left behind in the holes. I checked continuity of the pins at the chip in the proto area against the original pin locations, and everything matched up, so it seems like an acceptable fix. I don’t have teeny solder wick, so I’ll leave it.

-Q14 is raised WAY far above the board, at an angle. He mentioned having a lot of trouble with the tiny solder pads on the smaller transistors (who hasn’t) and ended up pulling and replacing Q14 multiple times because he wasn’t confident in his connections. This one worries me, because even with a magnifying glass, there’s so much “junk” around the solder pads that it’s really tough to tell if there are any bridges or shorts.

So… on to the troubleshooting!

WITH STIM CONNECTED:

Power Supply verified at 11.63v
-ve on pin 32, +ve on pin 20: 5.02v
-ve on pin 19, +ve on pin 20: 5.02v
-ve on pin 02, +ve on pin 20: 5.02v
-ve on Proto Gnd, +ve on pin 16: 10.96v
-ve on Proto Gnd, +ve on U5, left pin: 10.98v

Any suggestions? What can I do to get this board alive and breathing? I’m new to MegaSquirt & I’d love to get this thing up and running.

WP952016030795159538950795Pro.jpg

WP952016030795159548954995Pro.jpg

WP_20160307_15_48_02_Pro.jpg

Thanks in advance!

[slow_hemi6]

What exactly are you troubleshooting? Seems odd you are going all over the hardware for a connection issue. When you power it up on the stim do you get a prime pulse shown on the fuel pump led?
Have you had a look at this guide. http://www.msextra.com/doc/pdf/html/Meg ... p-1.4.html 5.4 is a good start, but read the whole thing.

[billr]

I'm not seeing any jumper to connect the "tachselect" to an input. Good friend or not, I'm not too impressed with the soldering. Many holes are not filled with solder through to the component side, often an indication of cold soldering. Soldering those small pads for the TO-92 devices isn't all that tricky for somebody who is skilled. Lastly, I see no reason to relocate the U7. If it is possible to reliably solder in wires for a remote mount in the proto area, then it should be possible to solder in leads from an IC (or socket).

[MooPlusMoo]

billr, I do not get a priming pulse when connected to the Stim. There's no firmware loaded onto the MS3, since he never got connectivity, so I don't even think we're at the priming pulse stage yet. The reason I'm troubleshooting the board itself for a connectivity issue is because since the board was never recognized by a PC (and the presence of some strange soldering) so I figured it'd be prudent to check the hardware first. I'm a mechanical technician by trade, so I'm more focused on the car than the electronics, but the friend passed it off to me as it's closer to my area of expertise. I guess.

So, U7 is in the Proto Area. Should I resolder it into position? Doesn't seem like location would be a huge issue unless he needs the Proto Area later (which he won't).

slow_hemi6, I did read the entire set-up document. I'd be happy to go through the actual connection process to the PC and post any logs or relevant data I get. The port check utility has no problem finding and communicating with both serial COMM ports on the PC, but can't find anything connected to either port at any baud rate. Therefore, can't load firmware.

I figured I'd just tear it down and verify all the basics, starting with the main board. If I can fix any issues at the fundamental level, and get the hardware put together correctly and functioning properly, PC connectivity and firmware loading will happen much easier. After all, if the hardware has problems, in my experience you're setting yourself up for software problems down the line.

Thanks for the quick replies, guys.

[slow_hemi6]

Do the loopback tests for the cable and main board shown in 5.4 in the set up manual.

[DaveEFI]

I personally never mount transistors like Q14 tight to the PCB. There is no need to. And mounting them clear of it allows you to check the soldering, if needed.

With all the bits you've spotted, I'd be inclined to send it to an experienced MS constructor for checking and or repair. But it sounds like it would be best with a new PCB.

[MooPlusMoo]

DaveEFI - I agree with the small transistors; I too prefer mounting smaller components above the board, especially when the contacts are small and there's a need for visibility in a post-soldering inspection.

I'd be fine with building a new PCB for this guy if you all agree that would be the best step. For what it's worth, it would allow us to rule out any variables with the questionable nature of some of the soldering. I'm assuming that the MS3 CPU card and MS3X card are fine, since they're pre-built (and no magic smoke has been released from any components anywhere as far as I can tell).

slow_hemi6 - I ran the loopback tests in the manual, on both the DB9 cable I'm using and the MS3 board. After successfully testing the DB9 cable by shorting pins 2+3, I connected the DB9 to the MS3 board, hooked up a powered Stimulator, and again, the board passed the loopback test, i.e. after opening the COM1 port in TunerStudio, typing letters returned the same letters back from the board.

So, I guess we DO have communication with the board... it just doesn't want to accept firmware. Plus there are definitely some issues with the mounting of a few components, we can all agree on that. Next steps?

[DaveEFI]

It is a problem with home made boards when it's clear the constructor wasn't very skilled at it. It's often easier to just start again rather than look for faults. I think DIYAutotune will supply a new board if you send the old one back - at a reasonable price. It's up to you as it's a time versus money thing.

[MooPlusMoo]

DaveEFI - I agree, he'd done some component soldering in college, but to be frank I wish he'd given me the board to put together for him from the get-go. I was really hoping to diagnose and troubleshoot this board in the hopes of finding a repair without resorting to replacing the entire board. I'd love to find out if there's a way to bypass or otherwise relocate some of the damaged components, particularly if they involve features we won't be using. For example, if we're going full sequential via the MS3X, can we bypass the batch-fire related components and give full control to the MS3X? Or does the MS3X work in conjunction with a signal from those components? These are the finer points where my MegaSquirt-specific knowledge falls flat.

I've got all the time in the world, and bags full of replacement transistors for all the affected components. But if you seriously think I should start fresh, I'll mail order a new kit before the weekend's over.

...and now I'm bummed about this project, so I'm gonna go wrench on something that still runs. Do we all vote to repair, or replace?

[DaveEFI]

I can't really advise, as I'm in the UK, and carriage and import duty make MS bits much more expensive here. Only you can decide what is the best cost/work compromise.

You can certainly omit the V3 board injector drivers if you're not going to use them.

[billr]

The PCB didn't look too bad to save, but there is some stuff on the solder-side that I'm interpreting as flux residue, not burned board. Maybe clean the board (both sides) and post new pictures? Congrats on the good-quality pictures, by the way. No doubt the quickest and sure-fire way is to build a new PCB, but if you have the time and skills, I would play with that one some more.

[slow_hemi6]

I'm still not sure the board is the "hinderance" to loading firmware as your socket voltage tests checked out and so did your loopback tests. Would you be happy to build a new mainboard to find your MS3 still wont load firmware? No one else seems to be asking this question and to me it is probably the most important point.

[MooPlusMoo]

Dave_EFI - I’m still familiarizing myself with the schematics and signal flow within the squirt, but omitting damaged components if they’re redundant is definitely something I’d like to look into. Then again, bypassing/“linking-out” certain things could prove just as tricky as actually re-installing the original part. So, again, I’m at that cost/work equation. I think ultimately I’ll mess around with this board until I reach a point where further repair risks actually causing further damage.

billr - Thanks, the photos actually came straight off my cellphone! Glad it’s got a quality camera. And as far as the flux residue, you’re 100% right- there’s a TON of it all over the board. The actual solder underneath seems complete, but man is there lots of flux! In my experience, you can’t have too much flux, but I was actually curious about finding a way to clean the residue off. Is there a component-safe solvent I can use? Most of it looks like hardened rosin from the core of the solder he used, so it’s pretty well caked on there.

slow_hemi6 - I’m glad you’re asking the questions nobody else is, it means you’re looking at this from a different perspective. Also, I agree- I want to condemn the board SO BADLY, but it keeps passing every test I throw at it. I’ve eliminated the PC and COM1 port from the problem, as well as the serial cable and the basic power supply portion of the board. The serial IC chip on the board isn’t the issue either, because it loops back the data sent to it. I want to dig deeper to figure out what's going on.

Anyway, my new plan is to clean the board as best I can, and I’ll re-post photos of it when I’m done. Are there any other tests I can perform? i.e. could the problem be in the actual MS3 CPU card? How would one go about testing for that? I'm completely ignoring the MS3X card for the time being, until we can get the basic setup working correctly. I've disconnected the ribbon cables for now.

I know it’s probably a pain in your collective butts, as you’re all “MS gurus” (not being snarky, genuinely respect you guys), but could I ask that the community take a really, seriously close look at the arrangement of the components on the board? Some transistors were omitted, other components were installed but I can’t find mention of them in the actual build instructions. Am I missing something painfully simple here?

Thank you all so much for your help. There’s a reason I brought this basket case to you guys!!

[billr]

I clean flux with lacquer thinner, followed by a hot-water rinse. Sometimes that will dull the P/N writing on ICs, but you always have the schematic to use in identifying them later.

[slow_hemi6]

I did not pick up on your location but I would suggest you send the MS3 card off to the supplier or one of the repair agents to be properly checked out. If it all checks out they will probably put some firmware on it for testing as well.

[MooPlusMoo]

billr - Lacquer thinner? That's perfect, I have a jug of it in the garage. I'll give it a good clean & report back.

slow_hemi6 - I'm in New England, way up on the Northern end of the USA East Coast. 40 min outside of Boston, MA if it's of any use.

It's a kit that was purchased from DIYAutoTune, and they've been absolutely awesome in every interaction I've ever had with them. Do they offer support services?

...you know, I'm probably asking questions now that I could answer myself. I'll give them a call to see if they'd be willing to take a look.

Cheers

[MooPlusMoo]

Just letting you all know (because I left this thread in limbo), the board has been sent to a professional.

He managed to get connectivity, load firmware, and throw a base map tune on it, so it's clearly not dead!

Thanks to everyone who chimed in- I really wanted to salvage the board myself, but in the end I'm glad we sent it out. I'm sure this isn't the last you'll hear from me... the ECU works, but as it always goes with standalone engine management, firing up the ECU is the easy part. Still lots of research to do, diagrams to read, and miles of wiring to install

Without posting on this board, I'd never have connected with the guru who ultimately enabled us to finish this project. So, thanks MSExtra!

Cheers