The times I've found those while going over the soldering as something to do while I think about the problem.............

Very often the escaping electrolyte eats through one of the capacitor's legs, these also show up as no longer attached to anything while re-working the solder joints.

I'm gonna try to check all those solder joints while I think about the problem too! A lot of electrolyte did scatter so hopefully I'll find something eaten up on the board. I already replaced all capacitors on the board. We'll see!

 

I'm gonna try to check all those solder joints while I think about the problem too! A lot of electrolyte did scatter so hopefully I'll find something eaten up on the board. I already replaced all capacitors on the board. We'll see!

Some manufacturers put brown glue in various places too, it goes brittle and corrosive as it ages - I've seen it eat all the way through component leads. One of the regular writers in Practical Wireless gave pictures of it dolloped on an oscillator board in a ham rig, it was commonplace in CRT PC monitors. Some manufacturers glue large electrolytics to the board with it - its often confused with congealed electrolyte.

The good news is; by the time the glue is a problem, its gone brittle so its relatively easy (if a bit tedious) to chip most of it away. The bad news; it can destroy small components like resistors, you have to wait for another the same model so you can identify what the component was.

 

Some manufacturers put brown glue in various places too, it goes brittle and corrosive as it ages - I've seen it eat all the way through component leads. One of the regular writers in Practical Wireless gave pictures of it dolloped on an oscillator board in a ham rig, it was commonplace in CRT PC monitors. Some manufacturers glue large electrolytics to the board with it - its often confused with congealed electrolyte.

The good news is; by the time the glue is a problem, its gone brittle so its relatively easy (if a bit tedious) to chip most of it away. The bad news; it can destroy small components like resistors, you have to wait for another the same model so you can identify what the component was.

Great idea! I'm gonna check all the components and leads on this thing because I do think that whatever happened to this board affected a lot more than just the caps! It probably affected more components too. All I know is when I first saw the board it had all this black stuff all over the traces and resistors and other components as well. And I have the exact same board in another elevator so I can easily compare to figure out what the component is. Here's a picture of the board after some work done to remove black stuff and replace capacitors and resolder some joints. You can see some traces were cleaned to make sure they have continuity and R27 still isn't completely clean. I'm still trying to find the last few problems...