Cleaning Rust

[scott2000]

Picked up an old Ashly compressor today and found loads of rust everywhere inside. It's all on the steel chassis, the transformer has a good coat of it and even all of the solder joints have a nice patina once the rust is knocked off.........

Any tips on how to address this?

It actually works pretty well still except for some noise from one of the channels ......


I'll get some pics up in a bit.....


Thanks!!!

 

[bluebird]

I was in home depot the other day and I was looking for the CLR (calcium, lime, rust) remover. I found a newer version that was a spray foam that might make things easier. Its made for crusty shower heads and faucets so I doubt its too strong.

Just make sure you test it on (a small spot) the pcb and maybe a pot you have laying around to see if it will damage any of the electronic parts.

Never tried it for heavy rust so do it at your own risk!

 

[scott2000]

Yeah it's real bad....I think it was found on the bottom of the ocean or something..... :-\

Thanks Blue!

 

[scott2000]

Can't believe it still works pretty good....... Going to disassemble it soon....... Humane society for gear.... :-[


edit....looks like a lot of this stuff is old foam  that has broken down....yuck......serial number 129....maybe late 70's version...SC-55

 

[ruffrecords]

I was going to ask how the stuff on the PCB could be rust. You only get rust where there is iron but the PCB tracks are copper and the solder is tin/lead. Decayed foam might be the answer. A lot of that you might be able to get off with a tooth brush.

Cheers

Ian

 

[sodderboy]

I would keep CLR away from anything audio except for the studio bathroom.  It is an acid that will etch/eat metal, clothing, and marble, along with the calcium, lime, and rust.  Plus it is water based. 

I have been using this WD40 product on fave tools and antiques, but it is a petro-based product that is not forgiving with plastics like vintage VU meters and knobs and it is made for soaking.

The surfaces can be carefully brushed with a brass brush, blown-off and see if it returns over time.
The solder connections can be cleaned with a small brass brush and flux remover but don't get the thing drenched.  It is better to keep the rust cleaning as dry as possible.
Mike

 

[scott2000]

I have been using this WD40 product on fave tools and antiques, but it is a petro-based product that is not forgiving with plastics

Awesome....I'll check this out.....I have plenty of rusty tools that I've been wanting to clean up anyhow......

I'll see what I can get away with on the unit.......maybe just experiment on the chassis ....... I'm tempted to just replace all of the components anyhow....

Ian are you sure rust only appears in iron or am I misunderstanding what you are saying???I've seen plenty of rusty old tin cans etc... in my younger years ??.....  The 394 definitely have rust on them too???... I have never seen patina on solder joints before but it is there ??... As well as their leads and those of some other components have rust.....

Thanks so much guys! Appreciate it!

 

[JohnRoberts]

Awesome....I'll check this out.....I have plenty of rusty tools that I've been wanting to clean up anyhow......

I'll see what I can get away with on the unit.......maybe just experiment on the chassis ....... I'm tempted to just replace all of the components anyhow....

Ian are you sure rust only appears in iron or am I misunderstanding what you are saying???I've seen plenty of rusty old tin cans etc... in my younger years ??.....  The 394 definitely have rust on them too???... I have never seen patina on solder joints before but it is there ??... As well as their leads and those of some other components have rust.....

Thanks so much guys! Appreciate it!

Rust is typically iron oxide from mostly in ferrous metals (reacting with oxygen).  Tin cans are typically tin coated steel (ferrous).

Many metals oxidize but with different color oxides. Aluminum oxide is white, copper oxide green, lead oxide (gray?).


JR

 

[iampoor1]

I am pretty certain that is just foam. Is that an SC-50? I have looked inside a few old ashley compressors. They all have a layer of foam on the bottom of the PCB to insulate it from the chassis.

 

[scott2000]

Yeah a lot of the stuff is foam....... There's also a lot of corrosion....... It's an SC-55 so it's just two of the 50s I'm guessing....

The 394 cans and leads are rusty and/or corroded as well as a ton of the resistors, op amp legs and sockets..... I'm waiting on a schematic/service manual to hopefully put together a parts list....I'm just going to replace everything after I get the board cleaned up....Shouldn't be too bad except for figuring out some of the resistor values........

I bought some of that WD40 rust remover that was recommended and it seems to work pretty good looking at how it's working on some of the screws I put in...... Smells like sulfur acid to me but, it says it isn't acid....

More excited about cleaning up some of my older tools with it really..... Will update....

Thanks!

 

[iampoor1]

Yeah a lot of the stuff is foam....... There's also a lot of corrosion....... It's an SC-55 so it's just two of the 50s I'm guessing....

The 394 cans and leads are rusty and/or corroded as well as a ton of the resistors, op amp legs and sockets..... I'm waiting on a schematic/service manual to hopefully put together a parts list....I'm just going to replace everything after I get the board cleaned up....Shouldn't be too bad except for figuring out some of the resistor values........

I bought some of that WD40 rust remover that was recommended and it seems to work pretty good looking at how it's working on some of the screws I put in...... Smells like sulfur acid to me but, it says it isn't acid....

More excited about cleaning up some of my older tools with it really..... Will update....

Thanks!

If its just a dual SC-50, I know the sc-50 schematic is floating around. If its not the same...I bet its pretty close. IIRC they use a vca built from discrete transistors, and use a quad opamp with a nonstandard pinout. I also think the output section uses 3 or 4 opamp sections in parallel. Gotta love that approach.  8)

 

[scott2000]

Exactly...... it's missing an external side chain and has a balance pot compared to the 50...... old 4136 and 301s everywhere but I like the sound......an effect.....and the 394s....

I'm wanting to be lazy and see a parts list....... Bought a schematic/service manual  etc...from that musicparts guy but haven't seen my instant download yet...... Hopefully it's not just a bunch of filler materials and an sc-50 schematic like is already out there...lol

I have an Ashly CL model with the DBX vca and I'm not thinking it's any slouch compared to the SC...... definitely a completely different sound all together but the SC ,although working pretty well considering, might not be showing it's full dirty sounding capabilities yet....

That wD40 rust remover seems pretty legit...just using it on the chassis in some parts and soaking some screws and nuts.....not too aggressive which is nice..... Thanks sodderboy for the tip.....


edit....the Musicparts "service manual" isn't but the schematic and it's chopped up into 4 pages that you have to actually remove some sections to make sense of it when piecing them together............ did have the power supply in it though.....I'm going to contact Ashly this week to see if they have something......

 

[nielsk]

There are a few brands of new generation rust removers like Evaporust on the market that are quite wonderful in comparison to what has been previously available. Much less caustic, easily rinsed off with water and said to be safe even for septic systems, they are fast working and easily applied.
If the rusty part can't be immersed, apply it to a piece of paper towel over the rust, a keep it moist with the remover until it's work is done.
I have spent untold hours removing rust on restorations of all kinds, this stuff has made my life much easier

 

[Gold]

There are a few brands of new generation rust removers like Evaporust on the market that are quite wonderful in comparison to what has been previously available.

Does this WD40 product or any other work on non ferrous oxidation? Right now on some multipin connectors like big 30 pin Tuchel's I use a stainless steel brush and alcohol. I've never been happy using a paste because it can get into holes and stay there. A liquid that doesn't harm plastic would be great.

 

[scott2000]

I've been very sparing with this WD-40...It seems to like rust...I haven't figured out how well it works on corrosion or various metals yet..... I did put it on a pcb and it was fine...I was too scared to leave it on for more than a couple of minutes......It's pretty mild sometimes but, it did take some paint off of a chassis I put it on....

Maybe someone else has more info....

I actually am interested in trying some of this Jewelry cleaner liquid...My wife has a tiny little tub of it and you put your jewelry in it and shake it around and it has a little brush you can use..then you rinse with water......I tested it on some can transistors and I'm kinda freaked out how good it seems to work but I want to get some more to test it further....There wasn't much left....

 

[scott2000]

Been messing around a bit with some Tarn-x....seems pretty safe and does a good job on some oxidized component legs and some of the traces....This board has what looks like solder traces???