Tutorial: "Deep Cleaning" An Amplifier

Discussion in 'DIY' started by Machineghost, Oct 22, 2009.

  1. Machineghost

    Machineghost Ghost in the machine

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    Thank you for your input Binkman
     

     

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  2. Binkman

    Binkman Addicted Member

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    You're welcome.. again very good illustrated article.
     
  3. Soldermizer

    Soldermizer New Member

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    The lazy method!

    If someone didn't "cut corners," how would the circle have ever been invented ? :)

    If you have a dusty old unit and perhaps not too valuable, consider the express method for a lazybones like me, who does not have the equipment, patience or skill to do it the through way described earlier. In other words, if you have lucked onto an ancient cobwebby pile of tubes and wires with the name "McIntosh" at a yard sale, by all means do a more responsible job. But on the other hand, if you are de-cat-hairing a Behringer INuke NU6000 (I've done it) or cleaning up an old Kenwood the neighbor gave you, try the Soldermizer method.

    I've had pretty good luck (not 100%) just basically giving the component a quick "shower" or bath. As noted, it's best to not immerse transformers, complex displays, etc. What I usually do is take the cover off, put unit in the sink and spray it with something that does not leave a residue. Ammonia in a sprayer is good. Let it soak in for a few minutes. Then if you have one, use the sprayer nozzle to thoroughly rinse off the top and bottom of the PCB's.

    Drying: this is the important part! Of course, letting the unit "drip dry" is the most important. If it's dry and sunny outside, that is a good place. I leave the cover off to maximize air flow and evaporation. Change the unit's position (upside down, sideways) to help get all the liquid out.

    Once the unit is initially dry then you need to: make sure it is completely dry. How you proceed depends on how impatient yoju are! I have an electric oven and can set it to very low (170 F by the control). I put the unit in the oven cold, then set it to 170 F and let it bake for about an hour. Then remove and let cool. I've had good luck cooking my electronics. The only casualty was an Apple Ipad (to loosen the adhesive.) It worked, but it killed the LCD. So if your unit has an LCD panel you may wish to avoid the oven.

    What if you don't have an oven, or the balls to try it? The best solution I have is to let the unit dry for many days ideally in an air conditioned room.

    Before power-up I like to lubricate (if needed) moving parts (usually with teflon spray). For electric and signal connections I like DeOxit.

    Connect to power, say a prayer, and turn it on.
     
    Last edited: Jun 27, 2014
  4. Machineghost

    Machineghost Ghost in the machine

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    Soldermizer - never let the unit "drip-dry". Get the moisture off and out of the unit as quick as possible after washing. Leaving it there will cause metal parts to oxidize no matter how fair the weather.

    I also dont quite agree with using ammonia. It is harsh.

    I use an industrial type hair-dryer (ETI brand) for drying the PCB and components and it works extremely well. Takes about 15 - 30 minutes and then re-assembly can start. No need to dry it for days on end unless you are hyper-paranoid.
     
  5. dfunghi

    dfunghi AK Subscriber Subscriber

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    Regarding drying:
    Wait for a very warm, sunny day if you can. Then place it all under a black tarp used like a ceiling (raised above equipment and open on sides) with a house fan blowing the hot air through it. Best done on patio or driveway and not on lawns as they have moisture. In no time at all you have a warm, dry board. Or as Arkay suggests find a food dehydrator.
    Also for cleaning outside of amps with baked enamel (like my Holman) this site has great advice
    http://www.porcelainenamel.com/Consumer_Information/Care_and_Cleaning.aspx
     
  6. Michon

    Michon New Member

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    7
    Thanks for the great tutorial ghost. I will try this method on an old Lafayette LA-200 that I have lying around. I will post some pics here when I am done.
     

     

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  7. N8Nagel

    N8Nagel AK Subscriber Subscriber

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    Just got a working but unbelievably filthy Marantz 2220B last night. Will be trying out some of these suggestions. I have a feeling that the main board will have to be removed and bathed before it is ever completely free of tar and nast.
     
  8. Charlton H

    Charlton H Active Member

    I haven't read the whole thread, but if no one has mentioned, some pots have a silicone grease in them to put some resistance on the knobs when turning them, it makes the knobs feel nice and stiff/tight when turning.
    You might not want to be washing that out.
    Also, don't some pots have lubrication of some sort?
     
  9. Albion015

    Albion015 New Member

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    1
    This is an amazing tutorial! But the idea of putting a PCB with all its components soldered in place into a tub of water just gives me the shudders. My thought would be to use a moist soft bristle brush to give the PCB a good cleaning, with minimal water exposure.Regular cleaning is very necessary, It wouldn't come out showroom clean, but far better than it would have been previously. I do have a very dusty receiver with that "stuck on dust" condition (won't just blow off with an air can). Looks like I may have to give this a try!
     
  10. BillWojo

    BillWojo AK Subscriber Subscriber

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    Albion015, no need to be afraid. When I worked for a major machine tool company the repair department took every PCB that came in for repair and ran them through a ultrasonic cleaner with a solution of Simple Green and water for an hour. Quick rinse in clear water, blow dry and than into an oven to bake dry. Out in the field I used a paint brush, Simple Green and the customers sink. Blow dry and find a warm spot for an hour or so. Stuff I worked on was loaded with IC's, caps, resistors a few trimmer pots etc. So far all the pics in this post show mildly dusty boards. I have pulled boards out of card cages that looked like they were covered in tar and dirt. No components were visible at all. As long as the machines were powered up and kept warm they kept on running. Shut them down for a weekend and humid air got to them and they wouldn't function. Moisture in all that dirt and oily coolant caused voltages to start leaking all over. I fixed a bunch of CNC control systems using that method.
    Even did a number of wire wrap logic boards this way. Couldn't even see the wires on some of them.

    BillWojo
     
  11. Machineghost

    Machineghost Ghost in the machine

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    Yes, the pot shaft grease does not wash out unless you make it a mission to do just that. I have found that in 99% of the cases the potentiometers smooth action gets restored after washing.
     

     

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  12. Machineghost

    Machineghost Ghost in the machine

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    Big companies like McIntosh, Luxman, Mark Levinson and the like wash all their PCBs, after assembly in huge "dishwasher" machines.

    The trick is to dry it all properly. And never get the transformers wet.
     
  13. H/K crazy

    H/K crazy Active Member

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    I have a book to suggest that explains some good techniques for restoring / cleaning tube gear. It's written by Stan Griffiths and is titled " Oscilloscopes, Restoring a Classic". Even though this book details restoration techniques for vintage tube based Tek scopes, much of the info in the section dedicated to the cleaning of these units would also apply to the cleaning of tube audio gear. Stan has a huge collection of vintage 50 /60's Tek scopes that he cleaned using the methods in his book. Test equipment can be some of the dirtyist gear one can come across. If some members are intending to clean multiple units, he even has construction instructions for home brew cleaning tanks !
     
  14. H/K crazy

    H/K crazy Active Member

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    Little omission in the book's complete title, it's " Oscilloscopes Selecting and Restoring a Classic ". Stan Griffiths operates a Tektronix museum and has over 500 units in his collection. There is also a video on Youtube where you can see some of his restored items.
     
  15. leesonic

    leesonic Hold on, here comes the bass. Subscriber

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    This is a very interesting and informative thread, one which I have followed myself with a few modifications of my own.

    Firstly, if I plan on recapping the unit, I remove the old caps. No sense in trying to brush around caps that are going to be in the way, and it's usually the electrolytics that are in the way. I do this washing in either a bowl or the kitchen sink. I put just a squeeze of detergent in the bowl or sink, and then add hot water until it just starts to cover the board. I never let it get high enough to immerse the pots or switches.

    Once the board is washed and rinsed, I take it downstairs or outside and blow the water off using a compressor and an air blow-off gun. Even when you think you are done, there is always an area that holds some water, and the powerful air stream is sure to find it. Sometimes there are little areas on the board that are still dirty, I use a soft paintbrush with acetone to remove these. The acetone is also used to soften any glue that was holding down a cap. I don't usually bother cleaning the solder side of the board just yet, since this will be cleaned with flux remover once all the soldering is done.

    Lee.
     
  16. H/K crazy

    H/K crazy Active Member

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    The circuit board material itself can hold some residual water / humidity. I would wait a couple of days before attempting to do a power up to make sure that the boards are completely 100% dried. Better safe than sorry.
     

     

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  17. Smokin amps

    Smokin amps Active Member

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    My brother in law is a refrigeration tech. He uses his vacuum pump to pull a vacuum on a container that he has put his hearing aids in. He said all moisture gasses out without any problems. Maybe a 55 gallon drum laid on its side with the gasketed removable top could be a big vacuum chamber that could hold audio equipment and connect a vacuum pump connection to the small 3/4" plug in the lid.
     
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  18. Dusty Ol'Man

    Dusty Ol'Man Sitting here in Blue Jay Way Subscriber

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    I know this is an old post but something has to be added here. I work in the petroleum industry. I have to go through rigorous training in the handling and dangers of chemicals such as benzene. NEVER EVER USE BENZENE AS A CLEANER!
    Benzene is a known carcinogen. The 15 minute time weighted average limit for benzene exposure is 0.1ppm. Any product containing more than 5% by weight requires a VOC respirator. If you can smell it, you are being exposed to much more than that. Benzene can enter the body through the skin as well as the lungs. Don't let it contact your skin. Benzene causes blood production diseases such as leukemia. But it doesn't show up for many years after exposure. Then it is sudden and catastrophic. I cannot stress enough the dangers of this type of chemical. Unless you have the training and necessary respiratory equipment to safely handle it, DON'T!
    https://www.cdc.gov/niosh/npg/npgd0049.html
     
  19. Bubel

    Bubel New Member

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    2
    How to unlock this connector? Seems like its consist of 2 parts - blue on bottom and white on top - tried to pull white by the hinge but... should I apply more force?
    [​IMG]
     
  20. Grady Shades

    Grady Shades New Member

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    So helpful and really makes so much sense when you stop and think about it. Why would water be more dangerous than any other liquid. As long as it doesn’t have power there’s nothing to short I maybe wrong or oversimplifing something I usually am and usually do. I did this last night on an MCS receiver that would play consistently out of the right side but only intermittently through the left. I used laundry detergent and a paintbrush coated everything first (of course cover etc removed) then gently scrubbed with the brush and small amount of water provided by a handheld shower head then turned the water up and watched a mudslide virtually run out of it. Had to be at least a boxcar of cigarettes washed down the drain. When it was rinsed clear I turned it every which way I could then took a hairdryer and quickly went over all of it , then patiently went back section by section top to bottom turned it multiple times to check for trapped water, then a light misting of alcohol for myself I was ready for reassembly. Short story long it’s working perfectly now nothing is amiss with it. Thank you kind sir for giving me the confidence to do what seemed logical to me but was always discouraged by naysayers who I’ve never seen do anything much else really. Inspiration, perspiration and something.....inebriation maybe lol. Thank you sincerely.
    Grady
     
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