Should the glue beneath a component look like this?

My Logitech Z5500 won't turn on so I opened up the subwoofer to look for anything obvious. I found this inside on the circuit board opposite the big heat sinks on the back of the unit. Is this normal in appearance? What is this part and would it's failure cause the unit to not power on? Also, the fuse is not blown. I appreciate your help and have a look forward to hearing from you.

Hello TakesBlackMetalSrsly,
Yes, there is a possibility that the discolored glue can become conductive due to heat and age.
There's a good chance also that this glue may not be the cause of your unit not to turn on.
The glues I've experienced in the past created shorts and major component failures.
One experience in particular was a 14" computer monitor I repaired that once the faulty
parts were replaced, it went on to blow up the exact same ones again when I turned it on
to test it. This occurred twice, and it wasn't until I scrapped off ALL the offending glue that
the unit was finally repaired. And not long after that, more of these same monitors were
coming in for the exact same failure.
Try scrapping it off using a flat blade screwdriver, but don't scrape too hard, especially if the
circuit board is dual layered. You don't want to to be scrapping any tracks off.
Have a good look at the rest of the circuit board/s bottom and top that may have the same glue.
You need to remove that too.

Please let us know how you get on.
Regards,
Relayer

It looks to me that you have a leaking electrolytic capacitor somewhere on your board. Through hole components never had glue that I have ever seen.

Use iso alcohol and a bristle brush (like an acid brush) to remove all the residue, then inspect your electros for damage.

One other thing I forgot to mention:
There is a very high chance that this glue is corrosive and you need to have a closer look at the
inductor (marked: 6482) and the capacitor legs that it seems Logitech have piggy backed it onto
the top of the coil.
You need to check the inductor for continuity, just in case one or more of the windings have gone
open circuit.

Through hole components never had glue that I have ever seen.

Click to expand...

This is still a common practice with manufacturers. They glue certain components to the board for
two reasons that I know of.
(1) To keep those components from falling out during the solder bath application, and...
(2) To overcome vibration effects during transport. (Though I don't agree 100% on this last aspect).
Unfortunately when manufacturers in the early days of applying glues to hold down parts, they couldn't
foresee the long term effects the adhesives would have on components due to age and heat.
These days though, they use non-corrosive and long term glues that will never conduct. Usually looks
like pure white silicon.
Regards,
Relayer

Thanks. Nearly every solder has glue around it. I imagine there is so much glue because it's a subwoofer and therefore subjected to much vibration. Thanks for the advice. I'll post my progress.

Some considerations sound highly speculative. As far as I'm aware of, "glue" types used in electronic production don't become conductive unless they are completely burned (carbonized). Usual glue is neither corrosive.

Originally elastic glue often hardens over time, becomes brittle and looses it's fixing strength. In so far problems with glue aren't unusual.

Are there any indications that function loss is related to the glued components? I believe the problem is asking for standard fault finding methods, e.g. using a voltmeter.

Hello FvM,

Some considerations sound highly speculative. As far as I'm aware of, "glue" types used in electronic production don't become conductive unless they are completely burned (carbonized). Usual glue is neither corrosive.

Click to expand...

Have you ever done any domestic or industrial repairs on a constant basis?
Not only I have experienced this phenomenon, but colleges within the same industry (domestic appliance repairs)
whom I knew personally, have also encountered the same problem.
I have, since 1987, subscribed to an Australian electronics magazine, with a regular column called: "The Servicemans Log",
to which even he often comes across this offensive glue as well.
It not only becomes conductive over the years, but it also can corrode component legs.
Not all manufacturers in the 1980's onward, used this glue. It mainly depended on the manufacturer, but also where it was
actually fabricated and assembled. Roughly 80% of these appliances that were made in China and their methods of manufacture,
at times, could be considered dubious.
Many glues used also, were of the correct type. i.e. Never became conductive or corrosive.
Have you ever looked inside a television made in China, and compared the same product produced in Japan?
Major differences in assembly and care of how the product is made.
In the past, do you really think that countries like China, Malaysia, Philippines etc are going to adhere to exacting standards
that the likes of Panasonic, TEAC, Sony etc would like? No. If they could save a buck, they did.
Now days, the companies that contract work to other countries watch-dog them more closely. Also, due to better technology,
appliances can be made so much cheaper, more reliable and get assembled by robots.

Are there any indications that function loss is related to the glued components? I believe the problem is asking for standard fault finding methods, e.g. using a voltmeter.

Click to expand...

I did mention that:

There's a good chance also that this glue may not be the cause of your unit not to turn on.

Click to expand...

But there is a good chance that it may have corroded a component or two. Also, if the glue isn't removed, there's a future
possibility it may end up being conductive... At the same time, this glue on TakesBlackMetalSrsly's sub-woofer may not conduct or corrode, but would
you take the chance of a future problem?
Regards,
Relayer

Hello to ALL,
Here's a thread from another forum that has the same problems as discussed in
this thread.

Glue Problems

This is just to confirm that the problem is real...
Sorry for posting in an old thread, but I feel that this issue is important.
Regards,
Relayer