PCB Micro Blasting for Corrosion damage

crayzkirk

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Hi,

I've got some Williams boards that have really bad corrosion from battery leakage. Black under the solder mask. I've been reading a bit about Micro Blasting on a pinball repair site which indicated to use some wheat blasting media along with a Harbor Freight kit. I have a compressor and would like to try this. I'm not going to spend a lot of money on an ionizer however I would like to know how to protect the board from possible ESD damage while I am doing this. Ground the nozzle, myself, the board and ?

Thanks in advance.

Kirk S.
 
Use zep acidic toilet bowel cleaner, and a brass mini brush.

The solder mask will come off if it has been undermined.

The alkaline damage needs to be neutralized otherwise it eill continue later on.

It creeps up ic legs and eats them from the inside.
 
I ran a ground wire from the metal gun through the suction tube to reduce ESD on mine.

DogP
 
Thanks for the info on the Zep. I gave it a try however there are still areas that are black under the mask and it's not coming off. When I say bad, I mean BAD! Most of the RAM sockets and 1/3 to 1/2 of the board affected by corrosion.

I might have bitten off more than I can chew with this battery damage.

Kirk S.
 
Whaat?


Is it a mpu board?


If so it would cost more to salvage it. Unless its a later joust or bubbles revision...

Just saying... After shipping getting all the ic chips....
 
I had a Mario that had acid damage. After pulling some of the affected chips, the traces were gone underneath.
 
Revisions C, D and B CPU boards. The D is the worst and the cores are missing from the inductors. The B isn't too bad however I still need to pull the two rows of chips and one row of RAM sockets to get the top level corrosion and check the traces under the chips. That's a lot of de-soldering work along with cleaning the legs on all of the 4116 that was pulled. It's been a while since I've seen one this bad. It's not any fun trying to heat up the corroded solder joints...

Argh!
 
... It's going to suck


the alkaline gas does damage to the watchdog area... that took me forever to get on mine, and im still not done with it
 
I took these for repair, I should ask about battery damage. Yeah, I had a Defender with battery damage and the watchdog was eaten up. Pull a chip, sand down the area, speed wire fix, lather rinse and repeat. At this point, I'll probably just swap the boards for some spares and keep these for those cold weekends when I'm feeling masochistic. I've pulled the tops off of the RAM sockets and removed those. I watched a video by Clay on Youtube where he was using hot air to remove RAM. I can't afford all of that expensive rework equipment.
 
"The D is the worst and the cores are missing from the inductors"

???

If you mean the inductors at the top left at the power input..... All the PCBs I have and have had that have the inductors have no cores. I presume these are 'air wound' inductors and are not supposed to have cores.
 
The ram area, the zep acid wash helps make it easier to get at the solder, that horrible layer gets eaten at, which makes it easier to ball solder on the points and flux the FCUK out of it.

Otherwise you will have to have the board vertical and a iron one side of the pad and a sucker on the other to get it to re-wet.

It's, not easy.

Personally I would rather pay to have someone else do it with extensive damage.

Under a 4 in section is easy.... When your talking the whole left side of the MPU by thr clock to watchdog and over in the ram area...

Bravo, more of a repairer than I am... Takes a lot of patience
 
I took these for repair, I should ask about battery damage. Yeah, I had a Defender with battery damage and the watchdog was eaten up. Pull a chip, sand down the area, speed wire fix, lather rinse and repeat. At this point, I'll probably just swap the boards for some spares and keep these for those cold weekends when I'm feeling masochistic. I've pulled the tops off of the RAM sockets and removed those. I watched a video by Clay on Youtube where he was using hot air to remove RAM. I can't afford all of that expensive rework equipment.

You can get a cheapie hot air station to do this. I have this one:

https://www.amazon.com/gp/product/B01M32ZIWN/ref=oh_aui_search_detailpage?ie=UTF8&th=1

I never use the soldering iron because it's a piece of junk so you could get the cheaper hot air only. The hot air station works great and I've used it to scavenge parts just like you saw in Clay's video. It's also great to remove parts that are just stubborn and don't want to release after you've removed solder. You just gently heat the solder pads up and pop the chip out. You just need to be careful and go slow. It's easy to torque a chip removing it and break the package apart. Practice on a parts board first and once you get the hang of it you can pop parts of pretty easily.
 
"The D is the worst and the cores are missing from the inductors"

???

If you mean the inductors at the top left at the power input..... All the PCBs I have and have had that have the inductors have no cores. I presume these are 'air wound' inductors and are not supposed to have cores.

I checked another board and it has cores. Like a lot of the Williams boards, there were changes and I'm sure different suppliers. I'll take a picture and post it next week. I'm not going to mess with these for a few days.

And I'm not sure I have the patience for this either. I can see it being a learning experience where I learn to not do things like this again...
 
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