Problem #2:<\/strong> Sure the burned up resistors were replaced, but they never bothered to clean up the flux!\u00a0 This makes for an amateur-looking repair, and if the flux is still slightly acidic (like rosin flux), the acid will start eating away the solder joint over a long period of time. It also turns out that after I cleaned all the flux off, whoever did the repair gouged the board all up around the resistor holes with their soldering iron (not visible as the flux hides all that stuff).\u00a0 Classy.<\/p>\n Problem #3:<\/strong> On the subject of messy flux, at some point someone tried to clean up their flux mess on some other areas of the board with what looks to be a wire brush.\u00a0 Luckily this didn’t really damage the board much, but it looks absolutely awful.\u00a0 It cleaned up easily though.<\/p>\n Problem #4:<\/strong> Ok, so this is probably my favorite problem with this board as it completely contradicts what the shop claimed to have done with this board.\u00a0 Supposedly they went over every solder joint and checked them all again for broken joints, particularly on the connectors as those joints see a lot of stress, and it is very common to have broken joints there.\u00a0 Pathetically, many of the connectors had broken solder joints.\u00a0 This board was literally taken out of the package from the repair shop and inspected (thankfully) before putting it into operation, so I didn’t cause any of the broken joints.\u00a0 They’re hard to see with the camera, but they’re pretty obvious to the naked eye.\u00a0 I marked two that were the most obvious.\u00a0 They didn’t check over the solder joints at all :-\/<\/p>\n Problem #5:<\/strong>\u00a0 Oddly this wasn’t as prevalent as I thought it would be, but there were some cold solder joints from someone touching things up on sketchy 40-pin connector (also not replaced) that goes to the MPU board that is notorious for intermittent game lockups and the like as this connector carries the address and data bus from the MPU board to the driver board.\u00a0 Oh, and there’s some more wire brush action too.<\/p>\n Problem #6:<\/strong> Since we’re on the subject of the 40-pin interconnect, it looks like someone had gotten white paint all over the connector and even into the connector in some spots.\u00a0 I mean this is the original connector most likely, so it’s already going to have connectivity issues.\u00a0 We don’t need paint in there too to make matters worse.\u00a0 Why wasn’t the 40 pin interconnect replaced??<\/p>\n Problem #7<\/strong>:<\/strong> Corrosion\/rust.\u00a0 Now this is something that’s guaranteed to make this board not work in the short term.\u00a0 I have no idea how this was missed or why it was ignored.\u00a0 Again, I would not be proud to say this was something I worked on.\u00a0 Notice how the contacts inside<\/strong> the relay are corroded and nearby IC pins rusted.\u00a0 How does that happen?\u00a0 Sounds like water to me…\u00a0 What isn’t visible is the relay’s back EMF diode that fell apart when I removed it because it was so badly corroded. Also notice the burnt connector pin in the bottom right.<\/p>\n Problem #8:<\/strong> Improper part replacement.\u00a0 In the picture above, there are two ST TIP120 transistors.\u00a0 Oh cool, something that may have been done right.\u00a0 While this would work, the original parts are TIP122 darlington transistors.\u00a0 The TIP120 is a lower operating voltage version of the TIP122 (in this case, lower operating voltage could be very bad).\u00a0 Oddly, someone bought those TIP120’s new, and you can still get TIP122’s, so I don’t know why the TIP122 was downgraded to a TIP120.\u00a0 I haven’t bothered to check the circuit to see if the TIP122 really is needed vs. the TIP120, but the 50 cents to replace the two parts wasn’t worth the 5 minutes of analysis =).<\/p>\n Alright, I think that’s all the problems with this upgraded, “gone-over-with-a-fine-toothed-comb” board for $130.\u00a0 Now you’re probably wondering why I didn’t return this board and demand that it be fixed properly or traded for another.\u00a0 The sole reason I did not do this is because the PCB quality of this particular board is excellent.\u00a0 I’m thinking this was a later production PCB as the copper foil isn’t lumpy with solder under the soldermask, the soldermask isn’t flaking off, and besides all the problems mentioned, this board is in really good shape.\u00a0 I’d hate to get a crappier board in return for this, so I decided it would be best to do all the needed repairs myself as I know I can do a much better job than the repair place can, and if this is an example of their work, I don’t want another board that they’ve touched.<\/p>\n I haven’t taken pics yet of the completed board with every one of the problems above addressed, but it’s a night and day difference compared to what the board was.\u00a0 This is mostly due to the replacement of every connector on the board, and the replacement of the corroded parts.<\/p>\n","protected":false},"excerpt":{"rendered":" As mentioned in another post, I’ve been doing a little pinball board repair on a few System 6 boards.\u00a0 A driver board was purchased for $130 (I think) that supposedly was gone over, fully checked out, and guaranteed to be … Continue reading ![\"Solder](\"https:\/\/ahdesign.us\/blog\/wp-content\/uploads\/2012\/08\/flux_mess.jpg\" "\\"Solder")
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