This board isn't pretty, but is it cause for concern?
I've tried isopropyl alcohol & a toothbrush but it has very little effect.
Any experience/suggestions would be greatly appreciated.
Thanks
I've tried isopropyl alcohol & a toothbrush but it has very little effect.
Any experience/suggestions would be greatly appreciated.
Thanks
Stronger solvents could remove the printing on the PCB.
I use a glass fiber brsh, alternate is a brass wire brush.
Assorted tooth brush handle type sets, with steel, brass and carcon fiber etc. bristles are sold for such purposes, buy good ones, use board after careful inspection.
Try hot soapy water, rinse thoroughly later...just a last chance suggestion.
I use a glass fiber brsh, alternate is a brass wire brush.
Assorted tooth brush handle type sets, with steel, brass and carcon fiber etc. bristles are sold for such purposes, buy good ones, use board after careful inspection.
Try hot soapy water, rinse thoroughly later...just a last chance suggestion.
My go-to chemical for most cleaning that alcohol won't do is hydrogen peroxide and in either case a fine mist pump sprayer and rarely need scrubbing except with a long hair brush for such things as tube amps and a typical cheap shoe shine brush and/or old paint brushes trimmed to different lengths for everything else.
I spray/wash corroded terminals and PCB pads with Cramolin D5 red, let sit 1 minute, scrub with fiberglass (Radio Shack used to carry them but I think you need to search for these; my brush wore out) or nylon brush, and remove with 95% or higher isopropyl alcohol. What I see on your photo is corrosion, not flux. Isopropyl alcohol by itself is not a solvent for corrosion. Cramolin D5 should safely dissolve corrosion, and isopropyl alcohol will wash it away. Two washes would be desirable. Water is NOT wanted, so I do not recommend 90% or lower isopropyl.
And make sure to resolder all solder joints after that and remove flux.
That old axial Philips caps with transparent blue sleeves are notorious. When we measured these at technical education the teacher used to say that these had ranja as dieelectric (ranja is syrup). If it is in the feedback network a bipolar MUSE ES one is a better choice.
That old axial Philips caps with transparent blue sleeves are notorious. When we measured these at technical education the teacher used to say that these had ranja as dieelectric (ranja is syrup). If it is in the feedback network a bipolar MUSE ES one is a better choice.
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That picture reminds me of the janky older Hafler boards; frustrating.
I have used tiny brass bristle brushes to (carefully) try and remove the corrosion before. On environmentally at-risk situations, like car ECUs, amps, I will use an acrylic coating, clear, to help protect against that.
I have used tiny brass bristle brushes to (carefully) try and remove the corrosion before. On environmentally at-risk situations, like car ECUs, amps, I will use an acrylic coating, clear, to help protect against that.
What would be your strategy for removing the coating if desildering is needed? Or do you carefully paint/spray coating with a mask to prevent acrylic from drying on solder lands?
Thanks for the replies.
Here are some more photos.
Besides the oxidation, there is a layer of funk. I don't know if it's cigarettes (there' no smell) or just years of dust and moisture.
They're not pretty, but is this a serious concern?
I tried with IPA & a rag next to R18. You can see where I started to get down to the board a little.
These is from a Classe DR8
I have 2 that I run in mono for a pair of Magnepan MG3a's .
They're not valuable but they're great amps.
Here are some more photos.
Besides the oxidation, there is a layer of funk. I don't know if it's cigarettes (there' no smell) or just years of dust and moisture.
They're not pretty, but is this a serious concern?
I tried with IPA & a rag next to R18. You can see where I started to get down to the board a little.
These is from a Classe DR8
I have 2 that I run in mono for a pair of Magnepan MG3a's .
They're not valuable but they're great amps.
I would use foam cleaner applied with a brush and rinsed off with tap water followed by a day warm and dry.
Blowing the water off with compressed air would be useful too.
Avoid getting too much water based foam or water around the trim pot adjusters.
Blowing the water off with compressed air would be useful too.
Avoid getting too much water based foam or water around the trim pot adjusters.
Cotton wool bud. Try a chosen cleaner on a small part of the board it'll be clear from the state of the bud if it's removing gunk/corrosion or not. Then you can do the whole board.
Use something low abrasive really. An old white t-shirt. Cotton swabs. Pieces of old white t-shirt wrapped around cotton swabs. A new soft toothbrush also works OK but try to avoid touching the parts themselves too much. Point is to remove the layer of filth/mold so it can not become a conductive path. Wear a mask to prevent inhaling debris! A soft paint brush and a vacuumcleaner should be used too. Wipe all dust/dirt/hairs etc. just like normal house keeping practice. Clean, clean and clean everything. Beware of touching adjustable stuff like potentiometers. Replace all those very old Philips axial caps and the main bulk filter caps while you are at it. It needs complete resoldering after cleaning anyway.
Maintenance = 1. cleaning 2.checking + replacing aging parts 3. resoldering all joints
No maintenance because of (insert good reasons number 1 to x here) = waiting for defects
Defects = possible premature EOL'ed Maggies + at least 2 "How do I ...." repair threads.
Maintenance = 1. cleaning 2.checking + replacing aging parts 3. resoldering all joints
No maintenance because of (insert good reasons number 1 to x here) = waiting for defects
Defects = possible premature EOL'ed Maggies + at least 2 "How do I ...." repair threads.
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Simple Green? I haven't used it for this purpose, but it's considered 'safe' by meeting U.S. EPA Safer Products Standards and yet, it's what I use to clean my table saw blades of resin build up (which is tough stuff). Might be worth a shot, and you can also use it as your general household cleaner.
^^ A test on a throwaway pcb might be a good idea. It is a good suggestion! I never thought to use it for that purpose but in retrospect, having used it extensively to clean various items successfully, it might be worth a try BUT mix on using water to clean the residue off.
jean-paul is right about those blue axial Philips caps. I would replace them all without even thinking about it.
Hydrogen peroxide is highly reactive and attacks/weakens most organic materials (i.e. plastics) and many metals (copper), don't use it on electronics otherwise you are setting yourself up for future failure. Why give old electronics extra oxidative stress above what they've already suffered over the years?
I'd try things designed for the purpose, such as flux cleaner.
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