The Aussie Pinball Arcade
Aussie Pinball Forums => Technical Matters => Circuit Board Repair Guides => Topic started by: Steevsee on February 27, 2015, 03:49:00 PM
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Couple of quick pics of some WPC89 cpu boards with battery vomit.
First is from a TZ that lost direct switch inputs.
Surprised that's all that didn't work!
Notice the pretty blue deposits on the chips to the left of the battery.
I have replaced the board with a new original one at the owner's request but will be cleaning and rebuilding this one shortly.
The owner also had a DW with the same trouble,(no direct switch inputs) which also had battery related damage around the switch inputs. This was a result of a poor prior attempt to neutralise corrosion and despite a remote battery holder being fitted, the corrosion returned.(last pic)
This board was also replaced with a new original as requested by owner.
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Some more pics.
First is the area around U16 after initial cleaning.
Second pic shows a closeup of the ic pins that were beneath the blue deposits.
Lastly is a random pic from the second board which had supposedly been cleaned of corrosion. Yuck!
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every trace of corrosion must be neutralized and removed.
even the via's must be cleaned out. no use removing the top and bottom corrosion unless you remove the via corrosion. and the corrosion under the headers.
and if it has made its way as far as the housings for the switch rows / columns then these will have to be replaced also
on 2 occasions i have had to cut and replace several inches of row / column wire because when you stripped the insulation back the conductor was green / white with corrosion
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on 2 occasions i have had to cut and replace several inches of row / column wire because when you stripped the insulation back the conductor was green / white with corrosion
So, you can always get back to clean wire?
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every trace of corrosion must be neutralized and removed.
even the via's must be cleaned out. no use removing the top and bottom corrosion unless you remove the via corrosion. and the corrosion under the headers.
and if it has made its way as far as the housings for the switch rows / columns then these will have to be replaced also
on 2 occasions i have had to cut and replace several inches of row / column wire because when you stripped the insulation back the conductor was green / white with corrosion
Thanks Andrew.
Already did the corrosion removal/neutralisation.
Followed this guide. http://aussiepinball.com/index.php?topic=9108.0 (http://aussiepinball.com/index.php?topic=9108.0)
Thanks.
Interesting how it travels along the wires.
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on 2 occasions i have had to cut and replace several inches of row / column wire because when you stripped the insulation back the conductor was green / white with corrosion
So, you can always get back to clean wire?
depends how long its been left for. one wire needed close to 30cms replaced but the rest didn't need much
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I too have seen early stern mpu200 boards with corosion all the way up to the header pins for switch/lamp matrix.No amount of remedial treatment was going to allow me to remove and replace those headers.The solder joints were fossilized.Plus i have had experienced noobs tell me"its not that bad,you can repair it"
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Love the close up photos. Corrosion is not always what can be seen. A lot of the times, corrosion has traveled along sections of traces that look fine until you sand away the surface. The "through holes" are also notorious for hiding corrosion. As a hobbyist, I enjoyed repairing these boards. As a business, it is not worth it. But "when" I have the time, I do like working on the really bad ones.
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agree,as a hobbyist it is a challenge and a rewarding,experience to get one of these 35+ yr old boards working.but economically it is not worth the time and effort,when a brand new replacement board could be had for just over $200.
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your thoughts KEN,i am sure you have seen your share of battery corrosion.
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I get a lot of requests for corrosion repair.
Sys11s and WPC games are a real bear unless it's very minor.
Sys 3-7 games, you can sand/clean a ton and you won't go through traces.
Sys11s, if you look at the traces under the battery holder sideways, the traces lift!
I turn as many away as I repair. It's a ton of work, and since I'm doing it as a business, I'm not doing it purely for pleasure. I do enjoy the work - but I have enough coming in now that I can't spend 4-5 hours tidying up a roached board and charge someone $3/hour to do the repair work :)
I bought a bead blast cabinet and new air compressor for my shop last year, to use in cleaning up alkaline damage. Hopefully, I find some more time to invest in the process.