Cleaning the PCB board makes a Difference

[aidynphoenix]

I took apart my Yamaha M-4, im preparing for a recap, im still waiting on the caps to arrive. so in the meantime i wanted to get something started, I decided to clean all the boards, and connectors inside. first i used a basic electronic contact cleaner on the green backside of each board, this was cheap CRC contact cleaner, i tilted the board at a angle and allowed this to carry dirt off the board and collect into a paper towel, and used a toothbrush to remove the dust, dirt or whatever else was left on there.

than for the front side with the components i started out with a dry 1inch paintbrush, to remove the dirt and dust.

after i got rid of the dust and dirt, i used small amounts of deoxit d100 and coated all the component leads and solder connections with it, i used another 1inch paintbrush to spread it around and on everything.
i did this on both sides of the boards.

i used deoxit on the boards and solder connections because they were not shiny and clean looking like a fresh component, they were more dull and grey than a shiny chrome color.
i assume this is built up dirt corosion or oxidation.

I learned here in the past that when copper speaker wires that are exposed to air and oxidise they will loose signal quality.
i dont see why this could be much different than tinned copper connections.

My amplifer sounds much more open and crisp after the cleaning than it did before.
im hearing things in my favorite songs and they are suprising me.

im sure i will hear a bigger improvement after the recap, but i thought i would share the differences im hearing after simply cleaning the components, leads, boards and connections.

 

[aidynphoenix]

im wondering if it would be better for me to use deoxit gold for the leads and boards than d100, i guess the goal is to prevent the leads and connections from oxidation, and to keep them clean.

are there any products designed for that?

 

[Jon_Logan]

It shouldn't have made a difference, unless there was some leaky contamination bridging connections.

I think you "knowledge" of green speaker wires causing a degradation in sound may have played a part in your after cleaning impressions.

 

[ChrisMarantz]

If you think about it, the soldered connection of a through hole component is sealed where the component lead passes through the copper pad. The solder forms the seal between the component lead and the pad.

While the surface of the solder may oxidize over time, this does not effect the connection inside the joint of the connection.

 

[js1138]

Unless the connections are close enough to be bridged by tin whiskers.

 

[aidynphoenix]

It shouldn't have made a difference, unless there was some leaky contamination bridging connections.

I think you "knowledge" of green speaker wires causing a degradation in sound may have played a part in your after cleaning impressions.

may of have been some kind of bridging going on.
there was some kind of greasy layer in manny places in my m-4, i noticed it all over the place.
it was easyiest to see on the backsides of the boards because lots of dust had collected in it and it got darker.
in this image here you can see how dirty the chassis is, this is before i cleaned the boards, i circled some of the places where you can definetly see that something got spilled down in there.

the big transformer has some rust on it too, which definetly makes me think this amp has been wet.
sorry the image is so huge.

 

[aidynphoenix]

this is also something else that i have been unsure about.
on most boards that i have seen there is always some kind of protective layer over the backside of the boards,

i think thats what this is here on this unit, but it seems kinda wavy and bubbly, i havent seen anything like this before. it reminds me of spraypaint, kinda how if you repaint it after its dried, it might lift the paint back up and it will get wavy..

 

[ChrisMarantz]

It is called Conformal Coating. It protects the PCB from moisture, dust and chemicals.

You can buy conformal coat removal solvent, which you use when a trace or pad needs to be repaired. You can also buy the coating to reseal the board after the repair

 

[avionic]

You can buy conformal coat removal solvent,

In the "Force" we used tolulene to remove conformal coating.After work was completed it was resealed with conformal coat.

 

[jdurbin1]

You really don't want to leave cleaners with lube in them (like deox) on boards. They are not non-residue and the slight oil coating left behind will attract and hold dust over time, making a real mess to clean later.

John

 

[aidynphoenix]

You really don't want to leave cleaners with lube in them (like deox) on boards. They are not non-residue and the slight oil coating left behind will attract and hold dust over time, making a real mess to clean later.

John

what should be used to clean boards without leaving some kind of residue?

i have tried regular rubbing alcohol, and it leaves some kind of white stuff.
is that because its 70% isopropyl?

 

[Russellc]

In the "Force" we used tolulene to remove conformal coating.After work was completed it was resealed with conformal coat.

Bingo! Also known as "Print coat solvent" basically the essence of tolulene (airplane glue) so use with plenty of ventilation. I always found when restoring old Dyna stuff that stripping all the parts, cleaning the boards of 35+ years old gunk made a big improvement. This gunk can apparently get slightly conductive I figure...

Russellc

 

[Russellc]

what should be used to clean boards without leaving some kind of residue?

i have tried regular rubbing alcohol, and it leaves some kind of white stuff.
is that because its 70% isopropyl?

The aforementioned print coat solvent, (tolulene) left the old dyna boards with no residue, made the old red boards appear like new!

Russellc

 

[bsabel]

Would cleaning off the components help with heat dissipation, too?

 

[CallMeJoe]

In the "Force" we used tolulene to remove conformal coating.After work was completed it was resealed with conformal coat.

I worked at a major avionics manufacturer where we used an isopropanol/actone mix to strip off conformal coating.

 

[CallMeJoe]

what should be used to clean boards without leaving some kind of residue?

i have tried regular rubbing alcohol, and it leaves some kind of white stuff.
is that because its 70% isopropyl?

Rubbing alcohol has skin conditioners and other additives that do not belong on circuit boards. 99% isopropanol is best but 91% is much easier to find.

 

[Zygmo]

You can sometimes find 99% isopropanol in Pharmacys. If they don't have it, they can get it for you. I use it for cleaning tape paths and heads.

 

[Blue Shadow]

If you used the deoxit on the connections shown in the photos, this will help explain the improved sound. Those connections would benefit from a nice deoxit cleaning and provide better performance when clean.

 

[aidynphoenix]

yea i sprayed deoxit inside all those white plastic connectors, i tried my best to get the bristles of the bush down inside them.
i didnt think that alone would make any kind of difference.

i was considering upgrading all the internal wireing to something of a lower AWG. but i would be sure its tinned copper.
i would also need to buy new pins for each of the connectors,
the rca cables i will be useing when im done with this amp are a bit thicker than the wire that goes from the inputs to the boards, i was going to change that wire to the same stuff im useing for my rca cables.
was thinking i would actually just solder right to the boards.
and avoid buying new pins for the line in cables.
but im still trying to decide on that, kinda wanting to change all the white pin headers to black ones to match the theme of the amp

 

[Arkay]

I've also found that cleaning up the insides of gear can have a positive impact on sound. There are various possible explanations of why this might be so; without factual evidence, I won't claim to know which applies, and very possibly different explanations apply to different specific instances. Whatever the reasons, cleanliness is a GOOD thing in audio gear. Even if you don't hear a difference in sonics, clean gear will be able to dissipate heat better, which should extend the gear's life.


To the OP, congratulations on improving the performance you're getting from your M4.

To the skeptics who posted above, don't be too quick to assume this is all just psycho-acoustic self-delusion. It might not be.