Someone sure got tired of backbox breakins

In the 70s that was a real problem at our local arcade. Some morons found out that they could pry the backbox door slightly open, and then by poking a bicycle spoke inside, add credits by pushing the credit reel.

We installed alarms triggered by a micro switch when backbox door was out of place.

Nah... it only needs some very light scraping to become a perfectly good window glass.

Yes. Remove all socketed chips. Then scrub both sides of board with vinegar. Let it soak for a while, then rinse with clean water. Chances are, you might end up with a working board, but if the corrosion has gone too far, the board will unfortunately stop working in a few months.

My advice is, let the vinegar work for at least a few hours. Then soak the board in clean water again for a few hours (refresh the water and brush off the vinegar a few times).

OK as long as it is acidic, to neutralize the alkaline leak from batteries / NiCd cells.

These are definitely not horror pics!

Shrinkage of cap wrapper plastic is usually a sign of overheating caused by partial internal short. Replacing all is the thing to do.

A Neyens / Parker game. I'm crying...

World under glass...

Dirty Harry. Game in cellar was on when a hot water pipe burst. Steam caused some shorts between driver board and backbox back plate. Got the game cheap, managed to repair the boards
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Dot matrix controller board also slightly suffered from shorts to backplane...
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Looking at very crispy L1... must have been quite serious short circuit on the CPU board + oversized fuse.

Perhaps battery isolation diode got shorted and then the 5V went straight to batteries, exploding them and burning L1. Those Vartas have a best before date 2029, and I have never had any problems with Vartas leaking.

That makes sense. The LM323 regulator has a current limit, and L1 is quite heavy wire so it burning due to overcurrent is unlikely. Anyway, still might be because of battery charging attempt due to shorted diode.

Maybe I have never had bad enough battery damage to affect L1. Hope I never will

The hot rectifiers dry out the capacitor fast, so its ESR soon rises to a level where inrush current stays pretty low...

I once ran a simulation on the WPC 5 volt supply. With a 25000 uF cap at C5, the peak current at every half-cycle is about 25 amp, due to the cap charging only at peaks of cycles. With 10000 uF, much lower current and the ripple at 2 amp load was still well within LM323 regulators operating range.

The metal lid PIA and white ceramic RAM are cool!

I think it is Klimagott, German for "climate god".

ShThat happens. The board is salvageable, just grind away all carbonized black areas and solder in wires to rebuild missing board foils. Make sure to get rid of all damage. Carbon conducts electricity in all the wrong places and you dont want that.

How did that happen?

Usually the fuse blows only after coil has overheated enough and gets internally shorted.

Did the smoker start a fire?

I think that applies nicely to pinball, because the coils are usually connected to common +50V, with drive coming from negative side.

I was once offered a Flash Gordon, that had, as the seller said "some wear where the ball moves". Meaning the playfield was almost bare wood. Looks like the ball has been moving quite a lot in that Mata Hari

New rubber rings though.

Could we get back to pinball horror pics?

Fun Cruise is a flipperless game so it doesn't have flipper buttons. Looks to me there are 3 score reels and one silk-screened zero.