Varta battery corrosion damage on a 504 board giving me "main door open" error?

[br549autosales]

I have a couple 504 boards that are giving each issues showing the front door not being closed. I know the optics are fine, so I'm guessing the light corrosion damage where I removed the Varta battery is causing this. I've tried cleaning that area with white vinegar and letting it dry thoroughly but the board is still giving me the same door open issues. Is there a solution to this problem as far as a better cleaning method or should o just replace both boards? The corrosion was very little divi figured a good cleaning would have worked

[cowboygames]

You could try jumper wires to components on either end of the traces that pass under that battery, but it's hit or miss. Most people mess with it a bit and replace the board

[rokgpsman]

If the battery leakage ate into any board traces or solder pads then they would need to be jumpered for a reliable connection. If there is still residual corrosion or contamination on the board it can provide a path for extraneous electrical current to flow and that might interfere with some of the circuits. If the board was mounted vertically sometimes the leakage can go further than the immediate area when it drips, runs or falls downward.

Since the corrosion was so little maybe it is just one thing that is causing the problem.

The vinegar will neutralize the battery leakage and help prevent further damage but it may not remove all the dried contamination that's already there. You can try a more vigorous cleaning using a fairly stiff bristle brush and dish detergent, then rinse & dry well. Some people even put them thru the dishwasher before giving up. If the battery leakage got underneath chips sometimes it is unseen, we've removed chips to find nasty stuff underneath. And sockets and connectors on the board can get affected if the leakage went into them. There are places (some are people here on NLG) that will clean and repair boards, but you'd need to balance that cost with just getting another board. We've cleaned boards in an ultrasonic tank filled with water and liquid detergent, similar to a jewelry cleaner but larger. The vibrations do a good job shaking loose contamination and cleaning it. But the vibrations can damage mechanical parts on the board like crystals so it is a risk. Engineers recommend suspending the board in the liquid so the board doesn't touch the sides or bottom of the tank, minimizes the vibrations conducted directly to the board.

As cowboygames said it gets down to how much time you can spend working on it, and whether you just want to be done and get a replacement board.


our shop had something like this, we had a frame that suspended the board in the cleaning solution vertically or horiz so it didn't touch any part of the tank:

[br549autosales]

Ok, anyone have a couple of working 504 boards for sale?

[Retro tech repair]

I have never seen this problem but someone with a bad board check continuity between r115 and r53 on the bottom of the board. The 2 bads closest to eachother should have continuity. R115 is by j2 the smaller of the 2 connectors that mate with the motherboar and r53 is by j5 and u44.

[Retro tech repair]

ok so here is pics of what i was asking. one pic is the location of each resistor on the bottom side of the board. the other two are each resistor in question with a circle around the pad that is supposed to be connected. the trace that connects the 2 is the only door related trace i can find and it has a via directly under the printing that says bt2.

[therockinelvis]

OK I'm jumping in here because I have 6 boards with the same problem. Please post results and good pictures or video of repair. Have not been able to throw away these boards hoping a fix was possible.

[Retro tech repair]

I have never had this problem and dont have a board to test the repair on thats why i want someone with a bad board to check between those solder. Just a diod test on a meter between them would work.

[Retro tech repair]

Just noticed the only 504 board i have is actually a 502 that someone swaped the lable on not sure if that makes a difference on the door traces.

[qbert]

Tested a bad 504 board mine shows no resistance between those points. The connection is complete so you need to look somewhere else, but I do remember that this board was somewhat intermittent. Maybe someone else's results?
 
Rich
 

[Retro tech repair]

I wish i had a board to test with. Im surprised the problem is this big i have worked on a lot of s2000s and never had this problem. Some of the green batterys on them looked like a furry catipiler was stuck to the board.

[br549autosales]

Damn, I guess I'm just unlucky then, I have 4 boards doing the same thing, jot showing door closed, and on all 4 the battery corrosion was very little to none. Seems like I remember seeing a post on this problem in which someone said to put a jumper on the board where the legs of the green battery used to be and it solved it for them

[Retro tech repair]

finally ended up with a board that may have the problem you guys are experiencing. the board came in a machine and had the problem when i got it. it did still have the green battery installed but no corrosion what so ever so i suspect someone replaced it at one point. i checked the optics with an oscilloscope and the pulse was there but it was very weak and inconsistent. now i have good news for me but bad news for all of you. in soldering on wires to points i wanted to test i seem to have accidentally fixed the board but i have no clue what ic or point was causing the problem. has anyone tried to re flow that section of the board yet? when i remove the batteries i use a Hakko 808 Desoldering Tool maybe the boards are getting too hot and the solder joints are breaking.