Cleaning Old Components
1. General Cleaning
I purchase a lot of components and assemblies at rallies and sometimes this involves getting down on my hands and knees to look through boxes of dusty parts under the seller’s stand. As a result a lot of these items look the worse for wear and are frequently very dirty.
Individual items like valveholders, high voltage or standard connectors, spacers etc can be washed in warm water containing a mild detergent, thoroughly rinsed, dried with a cloth and left in a warm environment like an airing cupboard to remove any remaining moisture. This process also works for empty equipment cases but should not be used for enclosed items like toggle switches, transformers etc. where the water can become trapped.
A toothbrush is a useful cleaning aid.
2. Silver Plated Items
Valveholders, tuning capacitors and other similar items that are silver plated can become tarnished over the years. This does not have a major effect on conductivity as silver oxide is a good conductor but can look unsightly. One answer to this problem is to wash and rinse each item to remove any dirt and then immerse them in a Silver Dip solution (e.g. Goddards) for a short period of time which will leave them looking in an almost new state. Afterwards they should be thoroughly rinsed and dried as in 1. above.
A lot of PTFE B7G/B9A valveholders and the tuning capacitors from WWII RF27 units respond very well to this treatment.
White spirit and cellulose thinners are both good for degreasing parts and surfaces but the latter is much more volatile and aggressive and may spoil the appearance of plastic surfaces and components. White spirit is my preferred option but always use protective gloves and in a well ventilated environment as hydrocarbon based liquids are easily absorbed by human tissue but take longer to be broken down in the liver.
White spirit applied sparingly on a cotton wool bud or small stiff paintbrush can be used to clean old chassis of dust and grime. Finish off with a dry bud or piece of cloth as appropriate.
There are other degreasing agents.
4. Brass and Copper Surfaces
Brasso is an effective way to clean brass and copper items and the cleaned areas will remain bright for a good period of time, probably due to the oils in the cleaning product. However, it is a messy process and makes the cleaning cloth black so gloves will protect and keep your hands clean.
Brasso is very mildly abrasive but much less so than wet and dry rubbing down paper and will produce a shiny surface with the appropriate amount of effort.
5. Rotary Switch and Tag Strip solder Joints
A solder sucker will remove the majority of the solder and some pre-
A temperature controlled soldering iron will help in minimising heat damage to the surrounding insulation.
6. Box Cleaning
I have collected a number of Heathkit units over the years and most of the cases have gathered a lot of marks, cigarette smoke and whatever else lurked in previous owners shacks. I have found the best way to clean the cases (without the associated electronics!!!) is to give them a warm bath.
Remove the internal chassis and front panel assembly, mounting feet etc and run some warm water into the bath. If the case has sharp corners then put a rubber mat or similar in the bath to protect the bath surfaces. A non abrasive kitchen cleaner will remove the accumulated dust and dirt -
Caution must be exercised because the paint on very old units may be brittle or chipped and may come off very easily -