How do I clean a very dirty radio chasis?

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Robin Kiszka-Kanowitz:
I have some old Drake radios, T-4XC and R-4C. The previous owner did not have a dust cover and the tubes and chases are filthy, in fact all the components on the uper side are filthy. I have tried to dust them off with a paintbrush, to some degree of success, but it is not a good solution.

Does anyone have some good ideas how this can be cleaned?

Thanks and 73
Robin
OZ6ABM

Bob Koerner:
http://www.zerobeat.net/drakelist/

Steve Katz:
I've placed old radio equipment chassis in a dishwasher (be careful NOT to use the "heater" drying element in the dishwasher, it gets so hot that the plastic parts like dials will melt) with great success.  Since the Drake does not have a built-in speaker, there's not much to go wrong.  However, everything needs to be thoroughly dried before you power the equipment back up -- this is to be sure the water has baked or evaporated out of things like transformers, coil forms, etc.

One trick I've used is to (literally) place the whole chassis in the dishwasher lower rack (the upper rack may have to be removed to make room for the equipment), making sure the dryer element is shut OFF ("air dry" mode), and let it run with regular dishwasher detergent.  When the cycle is finished, I remove the equipment and let the chassis bake in the sun, outdoors, for about one day on one side (say, chassis "up") and then bring it indoors overnight, and let it bake in the sun, outdoors for a second day on the other side (chassis "down").  On hot, sunny days, this seems to be sufficient to bake out all the moisture.  If you're not in a sunny, hot environment, using a common hair dryer held a foot or so away from the chassis (to avoid overheating plastic parts), for an hour or so per "side" accelerates the process, although this is tough on the arms!  (I don't know how hairdressers hold dryers all day long...)

Using this technique on a Collins 75A4 that looked as though it had been dragged through dirt inside, it brightened up the entire chassis and most all parts.  What little dirt/soil/grease was left, I removed with a small toothbrush and gentle solvent like alcohol.  I wouldn't use tri-chlor or MEK or anything dangerous -- not so much for the equipment, but it's just dangerous stuff to use indoors.  And MEK is highly flammable.  Stick with gentle solvents.  Even "409" household cleaner does a good job on sticky parts.

Last step in the process is to spray a light-duty contact cleaner on switch contacts, and apply a drop or small spray of fine oil on switch indent mechanisms and bearings, to replenish any lubrication that might wash away, prior to rotating the switches and other variable component shafts.

By the way, vacuum tubes are definitely "dishwasher safe," and I've used the kitchen dishwasher on hundreds of tubes for many years, does a great job.  However, if the labels on the tubes are hard to read prior to dishwashing, they can become even harder to read afterwards (the detergent slightly dissolves the paint or ink used on the tubes)...in those cases, I place each tube in its own separate bin in the "silverware" tray of the dishwasher, and write down on a piece of paper which tube went where before I start the washing process.  That way, after they're cleaned, I can identify them in case the labeling becomes too light to read.

Some will take issue with the "dishwasher" method, but I've used it many times on revered equipment like the old 75A4, and never had a single operational or reliability problem.  And I've had many comments like, "Wow, did you just open the factory carton on this thing?"  It makes one smile.

73 de Steve WB2WIK/6

George Hicks:
I've used Steve's "dishwasher" method with great success.  I follow up on the air drying process with a gentle "blow drying" (using my air compressor and a low pressure output) to make certain I've gotten all the little droplets out from around the bases of tubes, including those little holes that the tube connector pins call home.  Just a little bit of water residue to cause corrosion and getting all the water out has always been of utmost importance to me.
If you find another method that works please share it with the rest of us.  

Terry Schieler:
I had good success with a product called "Big Bath" that is available in a high pressure spray can from Antique Electronic Supply in Arizona.  It packs a lot of pressure to get crud out of tight places, then it evaporates, so there is no significant drying process required.  I used this to restore a 1930 Philco cathederal radio that looked like it had been through a Peruvian mud slide!  Get the large size and use it freely.  My Philco required no additional cleaning after a couple rounds of the "Big Bath".  Good luck.  Terry, WØFM

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