What is the grey "goop' on PCB next to ceramic disk capacitors on PCB?

vbimport

#1

I have a Vizio plasma TV that suffered the “pop of death” (quite a common problem). In looking through the PCBs I noticed this one board with a bunch of grey “goop” like material mostly around the ceramic disk capacitors. This is a power supply board and I don’t see it on any of the others. What is this stuff? I’ve attached a picture that shows some of this next two green and blue disc capacitors. Thanks


#2

My guess is some kind of silicone insulating goop. Is it fully cured or is it viscous?


#3

I think they do that to keep the tall components from moving and eventually cracking the solder traces on the circuit board that the part is soldered to.
A LOT of gear dies becuase something moved do to heat cycling or vibration and then whatever that part controls quits working.
I fixed plenty of dead gear that all it needed was a part resoldered onto it’s pads on the circuit board due to it cracking away over time.


#4

@ Dartman , You are experienced from other posts of yours I’ve read.I think part of the problem is the lead free solder.The old lead type being softer & less sensitive to some movement. Just thought I would ask your opinion on that.


#5

Well most of the sets I used to work on were from late 60’s to early 80’s so I don’t think any of them had lead free solder in them.
They all tend to either eventually crack over time or just get a cold solder joint that didn’t flow properly becuase it wasn’t hot enough or clean at the pads.
The old stuff could cause health issues if you got enough of it in your system and was just bad for the environment so they stopped using it.
I’m sure I still have a bunch of the old style stuff, and plenty of the new lead free or silver solder as well. Knowing what I do now I prefer the lead free just to be safer to me when I’m using it but I would guess it could be quite a bit more brittle. The silver solder is nice, seems to supposedly conduct better and sure makes a pretty joint when your done:cool:


#6

[QUOTE=Dartman;2489563]I fixed plenty of dead gear that all it needed was a part resoldered onto it’s pads on the circuit board due to it cracking away over time.[/QUOTE] I totally agree, both my two previous televisions suffered from this phenomenon.

If possible, turn around the pcb and check all the solder pin connections. If possible resolder them with a tiny solder point/tip.

The old stuff could cause health issues if you got enough of it in your system and was just bad for the environment so they stopped using it.
Yeah, but it was so much better than the new stuff. I still have some old S39 liquid for better soldering. :slight_smile:


#7

Well I used to suck in the smoke every time I was doing any repairs and never worried about it, then it came out how bad it can be for you but I still grab whatever solder roll is handy when I need to do something and I still have about a pound of the old Weller multi core that is thin and just works so nicely. I try to be a bit more careful about just inhaling the smoke while working but I’m still here and I think the brain still works all these years later.


#8

Having worked in a factory that assembled circuit boards, it looks like a type of glue to keep the part in place as it goes through what is called a ‘wave solder machine’, so the part doesn’t fall out or get half soldered. I worked on boards that had parts not fully flush to the circuit board, heated the leads with a soldering iron and made them flush then sent them on.


#9

Thanks for feedback. It is cured and does appear to be some glue type substance. Probably used to keep some parts in place or separated as mentioned in on of the replies.


#10

Well I guess that’s the answer then, more to keep parts from falling out while waiting to be solder flowed, makes sense.
I’m sure it doesn’t hurt that it might also lessen cracked solder joints over time too.