The last person who worked on your board didn't do a very good job cleaning it up.

It happens often. A lot of people skip that final, crucial step of removing flux.

The brown stuff is rosin flux - somewhat like pine sap It's a component in rosin core solder that helps clean things and helps the solder flow.

Flux should be removed after soldering. Kind of like wiping ones posterior after using the facilities.

How to remove it...

91% or better isopropryl alcohol or naphtha

IPA can be had at most drugstores or department stores. It's more expensive than the 70% stuff, as it's diluted less.

Naphtha is cheaper, but has a stronger odor and may be more flammable.

Take a toothbrush, and some IPA, and scrub.

If it's really stiff and dried out, you can take a dental pick, or something similar, and scrape some of it away before cleaning it.

The way you get the best results - get some kimwipes.

You can buy these at medical supply stores, on eBay, and some office supply stores. I mail order mine, as I couldn't find them locally. Kimwipes are lint free, and are softer than tissues.

I take a brush, and brush the area I'm cleaning with IPA or Naphtha, and then put a kimwipe over it, and brush it some more.

The kimwipe absorbs the flux. Otherwise, you're just rinsing it around the board.

Some really tough areas, you may use 2 or 3 kimwipes - but once you get the process down, the board will be clean and residue free.

Another tip - use *good* solder. Not just whatever crap your local radio shack or hardware store has on the shelf. I use Kester 24-6337-8800 - it's 'no clean', meaning *technically*, the flux doesn't need to be cleaned up, but do it anyways! Any job worth doing is worth doing right! And it's not that expensive, about $18 per 1# roll. Most people will get a lifetime's worth of service out of a single 1# roll. I get mine from Kimco - gokimco.com - but since you're in Canada, you'll probably want to find a Canadian distributor, so it arrives faster and costs less to ship.

I'll be honest - you're gonna be mad at that board by the time you're done. It's gonna be a bit of a pain to get clean - but it'll look so much better when you're done - even though you won't be able to see the back once it's installed!

One more thing...

If you've never done board work before, don't start with this board. It looks like it's still pretty nice. Not doubting your skill, or implying anything - just suggesting you find some old junk electronics to practice on first. Work your way up to it. The clue is looking for something *old* - any recently made electronics won't be similar to that board at all. Practice til you can remove and replace components without lifting traces or burning the board. I do a lot of PCB repair for a number of customers,and more often than not, if someone sends me a board after they tried to fix something, they've made it worse, because they shouldn't have been in there to begin with. A nice unhacked board is easier to diagnose, which means it costs people less in the long run, and it's also much easier to repair without doing damage. The way you fix a damaged PCB is not always cosmetically attractive. Some people care, some do not.

So, ask questions, practice on something that's not important first, and don't be afraid. Just be respectful of what you're trying to repair.

Oh yeah, don't forget to have fun!

It is.
Most of what you've pictured is someone's ham handed repair attempt.
It's possible that the 5V circuit isn't working due to these "repairs", but I need to look at the original thread.
--
Chris Hibler - CARGPB #31
http://www.Team-EM.com
http://webpages.charter.net/chibler/Pinball/index.htm
http://www.PinWiki.com - The new place for pinball repair info

Soldering looks fine to me, just a lot of flux left. I wouldn't expect that it is causing any problems, but now that you have the board out you might as well clean it up.

Wouldn't call it ham-handed, just not cleaned up.

In picture 2 it looks like there may be a cold solder joint. I suggest cleaning it up and reflowing solder on the pins.

Maybe. Maybe not. If the tech didn't know enough to use "no clean" solder or enough to clean it up, how much faith would anyone have that the tech was able to remove the OEM connectors without damaging the through holes and pads?
--
Chris Hibler - CARGPB #31
http://www.Team-EM.com
http://webpages.charter.net/chibler/Pinball/index.htm
http://www.PinWiki.com - The new place for pinball repair info

Second picture upper right pad looks slightly rotated - that pad may have poor/no connection to the traces above and below it. As others have suggested you won't be able to tell much until you clean it up. And I'd reflow everything that's been touched as well. In fact I'd reflow all the pins on all the connectors.

Should look pretty good when you're done – the board seems to be in pretty good shape. The problem is flux residue and possibly the quality of the soldering and maybe one or two pads that will need to be reattached to their traces (if so, scrape off the solder mask over the trace(s) and put a thin wire across the trace, the pad, and the trace on the other side).

Here's a good tutorial on that: http://billmaudio.com/wp/?page_id=204 There are lots of other examples as well - just do a google search for PCB trace repair. But as I said, that board actually seems to be in pretty good shape; shouldn't need much work.

The flux in your pics is really just a minor detail and shouldn't cause problems. Cleaning the flux off is a waste of time if you can't get the board working first.

I just read your first post. You need to determine why the game is still resetting. Have you consulted the pinwiki and performed the steps in there one by one? That is going to be how to resolve your problem.

If you wiggle connectors while the game is working can you consistently get it to crash? If so, you found the problem. If not, move on to testing voltages at the MPU. Then testing the bridges and if they test good, reflow solder on BOTH the top side pins and bottom side pins OF THE BRIDGES. Also reflow solder on the large capacitors at the same time.

Honestly, tracking down a case of the resets is a connector wiggling exercise first, followed by voltmeter testing, followed by soldering. Consulting the pinwiki will elaborate on all these steps.

Ok, if you tested the bridge (BR2), and it tested good, you probably just need to reflow solder on the top and bottom of that bridge and whatever traces and components it travels to thereafter (capacitor, ect.).

Most often people replace bridges that are completely fine in this exact scenario. Yes, it could be bad, but it is probably just a crappy solder connection, or bad PTH (plated-through-hole) on the PCB if the bridge tests good. That is the reason the wiki has all the redundant connection mods in it. It is because these connections from top to bottom of the PCB fail all the time. It is easier to add wires everywhere than to address the actual failed PTH connection/trace, as they are tricky to reach and time consuming to address/fix.

Most all pinball problems can be traced to a connection problem. Don't think of "connections" as just plugs either. A solder pad under a bridge/cap/resistor/ect. is also a CONNECTION in a pinball machine. If things are "just barely touching" because of heat, corrosion, or bad solder work, that can cause random resets on a game like you are describing. A voltmeter's continuity checker is your friend. You will use it more often than any other test you ever perform on a pinball machine.