How to clean my tuning capacitor?

It's an old (1960s AM radio) air dielectric, planetary drive with ball bearing 6X reduction). It's a very small mechanical cap measuring about 9/8 inch square by 11/16 height with closely spaced plates (150pF and 100pF). Problem is, the oscillator section jumps about 5KHz out of 1Mhz or maybe 0.5% with small adjustments to the cap. It appears it may be losing a ground connection (or high resistance) to the moving plates, or possibly some dust between the plates. I assume the ground connection is made through the ball bearings. I tried spraying some contact cleaner on the ends of the shaft but it didn't help. What would you suggest to restore the capacitor to it's original condition? I thought about soaking it in alcohol, but maybe that's not a good idea.


Reply to
Bill Bowden
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These guys have cleaned a lot of air caps. Mikek

Reply to

There's usually a spring blade contact pressing against a turned shoulder on the shaft just before it enters the bearing. The contact is often silver plated, which can develop a heavy black tarnish. AFAICR this has never caused a problem - YMMV.

Blasting away at the inter-vane spaces with contact lube will leave a film on the vanes that alters the dielectric constant. You can get aerosol dusters which are just air or some other gas, if you've got an accumulation of settled exhaust particulates found their way between the vanes, you may want to consider a non lubricating solvent spray.

If the bearings get washed out by solvent - as long as it has a grounding blade for the moving vanes; you can carefully re-apply grease with a glue applicator syringe, normally you'd use something like Elvolube contact grease - but last time I tried to find some it seemed to have vanished from the market.

I'd use Finnish line PTFE bicycle grease - but only if the cap has a grounding blade to the spindle.

Immersion in solvent may be best avoided if it has mica compression trimmers on the outside of the frame.

Reply to
Ian Field

"Bill Bowden"

** What did you use - Freon ?

A few drops of WD40 on the bearings at each end of the moving plates usually fixes it. Do not spray, use a syringe or the tip of a small screwdriver to apply the liquid.


A customer decided to fix his FM tuner ( Quad FM3) with the same problem.

He sprayed WD40 all over the gang and nearby PCB - the oil layer left behind offset the local oscillator frequency by about 30 MHz, so right off the FM band completely.

After a lot of rinsing with turps and drying with hot air, I got it back.

... Phil

Reply to
Phil Allison

The only part of that I disagree with, is the use of penetrating oil on the bearings - its partly solvent and most of it evaporates.

The original grease was always pretty thick sticky stuff, but some later manufacturers have used a thinner white grease - may or may not be PTFE grease.

Reply to
Ian Field


Nice pictures of ultrasonic cleaning results. Look like new.


Reply to
Bill Bowden


Yes, there is a spring blade contact at the opposite end of the shaft as the ball bearings. Didn't see any silver, the blade appears copper or brass. I soaked the cap in alcohol for a day and moved the plates many times. Then I dried it the sun and added a few drops of WD40 to both ends as Phil suggested. I removed the mica insulator and cleaned it separetely. Cap works much better now, but still a little eratic near the bottom of the band where the plates are near fully closed. Might need some more WD40, or maybe some thin sewing machine oil?







Reply to
Bill Bowden

It may be that there's some corrosion on the rotor shaft where the 
capacitance change is erratic, or it might be that the spacing between 
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Reply to
John Fields

You'd want to be careful if the cap has mica compression trimmers - prolonged ultrasonics can chimble away the mica, and you certainly don't want the solvent to leave any residue.

Reply to
Ian Field




der on


The cap got more erratic today, so I applied more WD40 and then lost all signals except one 50KW station about 7 miles away. Everthing appeared normal, oscillator and antenna circuit both on correct frequency. It appeared the Q of the antenna circuit degraded drastically due to WD40 which may have spilled on the capacitor plates. So, I tried measuring the resistance of some WD40 on the table and it measured over 20Megs (limit of the meter). A few hours later, the cap started working again, so I connected a 10 Meg resistor across the antenna capacitor plates which made very little difference. So, it's still a mystery how WD40, with such high resistance, effects the Q of the capacitor. Maybe it caused some corroded point to get worse?

I saw a 16 ounce (45 watt) ultrasonic cleaner at Harbor Freight for $29.99. I might invest in that if I can think of some other uses. I hate to buy it just to use it once.


Reply to
Bill Bowden

You created a coating that increased the dialectic constant for the plate that tune's the antenna..

THen again, could be the differences between G and E line effects..


Reply to

WD40 isn't suitable as a lubricant for the bearings or grounding plate. You want GC Tunerlube, white lithium grease or even Vaseline in a pinch. Use a syringe, and inject it sparingly.

WD40 hardens into a hard to remove, non-conductive coating. Look at the MSDS and you'll see that it is classed as a solvent.

Reply to
Michael A. Terrell

"Michael A. Terrell = Trolling Psycho"

** The OP needed a contact cleaner FIRST.

WD40 is that and then it leaves a thin, oily film the lubricates and protects against moisture.

** Much the same as WD40.


Using any sort of grease is never going to help a bad contact.


** Not unless there is a LOT of heat involved and no moving parts.
** Which makes it a good surface cleaner AND totally contradicts everything you just said.


FOAD you stinking TROLL !!!!!!!

Reply to
Phil Allison

"Bill Bowden"

The cap got more erratic today, so I applied more WD40 and then lost all signals except one 50KW station about 7 miles away. Everthing appeared normal, oscillator and antenna circuit both on correct frequency. It appeared the Q of the antenna circuit degraded drastically due to WD40 which may have spilled on the capacitor plates.

** More likely rust or dirt particles from the bearings made it between the plates - carried by the EXCESS of WD40 you applied.

I have used WD40 successfully on intermittent tuning gangs in FM receivers many times, never any problem.

BUT I used it sparingly and carefully !!!

You may need to use an evaporative cleaner on the plates now - ie stuff that smells nice and disappears in seconds if you spray it on your hand.

... Phil

Reply to
Phil Allison

It is basically Kerosene, and was developed to spray on the ignition system of airplanes. It isn't, and never was a contact cleaner.

Neither is pissing your panties in public, Phylis but you get so much joy from the warm piss running down your legs while people point at you and laugh.

yawn. Gun collectors despise WD40, because it does exactly what I said, It doesn't require heat, just time for the lighter distillates to evaporate.

Only in your incredibly small mind. All it does in his application is temporarily soften the bad lube. It does absolutely nothing to remove oxides from the surface of the bearings, or grounding plate.

Yawn. You need to stop projecting all your shortcomings, you ignorant bitch. Take your Midol and go away till it kicks in. Hopefully, Menopause will calm you down some day soon. Seen any 'Chemical fuses' lately?

Reply to
Michael A. Terrell

"Michael A. Terrell = Trolling Psycho"

** WRONG - there is NO kerosene in WD40 whatever.
** It is actually one of the very, very best.

You know nothing, LYING stinking FUCKWIT

** ROTFLMAO !!!!!!!!!!!!!!

Might as well claim what demented chimpanzees think.

Wot a LYING, c*ck sucking, retarded FUCKWIT !

** The sooner some decent citizen puts a criminal scumbag

like YOU out of his misery - the better.

Reply to
Phil Allison

Nothing, coherent.

WD-40 AEROSOL Chemwatch Independent Material Safety Data Sheet Issue Date: 29-Jun-2010 CHEMWATCH 1950-6 C9317EC Version No:12 CD 2011/2 Page 1 of 7





"61011 -7g", "61006 -60g", "61001 -150g", "61002 -255g", "61031 -275g", "61003 -300g", "61009 -350g", "61032 -375g", "61004 -425g", "61033 -500g"




¦ The use of a quantity of material in an unventilated or confined space may result in increased exposure and an irritating atmosphere developing. Before starting consider control of exposure by mechanical ventilation. Application is by spray atomisation from a hand held aerosol pack. Lubricates, corrosion inhibitor, displaces moisture, penetrant, cleans (spray). SUPPLIER

Company: WD-40 Company Australia Pty Ltd Address: Level 2, Suite 23, 41 Rawson Street Epping NSW, 2121 Australia Telephone: +61 2 9868 2200 Emergency Tel: 1800 024 973 Fax: +61 2 9869 7512





¦ Flammable. ? Avoid contact with skin. ¦ Irritating to skin. ? Wear suitable gloves. ¦ Risk of explosion if heated under ? To clean the floor and all objects contaminated by this confinement. material, use water and detergent. ¦ Repeated exposure may cause skin ? If swallowed, IMMEDIATELY contact Doctor or Poisons dryness and cracking. Information Centre. (show this container or label). ¦ Vapours may cause drowsiness and ? This material and its container must be disposed of as dizziness. hazardous waste. Section 3 -COMPOSITION / INFORMATION ON INGREDIENTS

NAME CAS RN % white spirit 8052-41-3. 45-50 paraffinic distillate, heavy, solvent-dewaxed (severe) 64742-65-0. 15-25 isoparaffins petroleum hydrotreated HFP 64742-47-8. 12-18 carbon dioxide 124-38-9 2-3



? Avoid giving milk or oils. ? Avoid giving alcohol. ? Not considered a normal route of entry. ? If swallowed do NOT induce vomiting. ? If vomiting occurs, lean patient forward or place on left side (head-down position, if possible) to maintain open airway and continued...

WD-40 AEROSOL Chemwatch Independent Material Safety Data Sheet Issue Date: 29-Jun-2010 CHEMWATCH 1950-6 C9317EC Version No:12 CD 2011/2 Page 2 of 7 Section 4 -FIRST AID MEASURES

prevent aspiration.

? Observe the patient carefully. ? Never give liquid to a person showing signs of being sleepy or with reduced awareness; i.e. becoming unconscious. EYE

¦ If aerosols come in contact with the eyes: ? Immediately hold the eyelids apart and flush the eye continuously for at least 15 minutes with fresh running water. ? Ensure complete irrigation of the eye by keeping eyelids apart and away from eye and moving the eyelids by occasionally lifting the upper and lower lids. ? Transport to hospital or doctor without delay. ? Removal of contact lenses after an eye injury should only be undertaken by skilled personnel. SKIN ¦ If solids or aerosol mists are deposited upon the skin: ? Flush skin and hair with running water (and soap if available). ? Remove any adhering solids with industrial skin cleansing cream. ? DO NOT use solvents. ? Seek medical attention in the event of irritation. INHALED ¦ If aerosols, fumes or combustion products are inhaled: ? Remove to fresh air. ? Lay patient down. Keep warm and rested. ? Prostheses such as false teeth, which may block airway, should be removed, where possible, prior to initiating first aid procedures. ? If breathing is shallow or has stopped, ensure clear airway and apply resuscitation, preferably with a demand valve resuscitator, bag-valve mask device, or pocket mask as trained. Perform CPR if necessary. NOTES TO PHYSICIAN ¦ Treat symptomatically. For acute or short term repeated exposures to petroleum distillates or related hydrocarbons: ? Primary threat to life, from pure petroleum distillate ingestion and/or inhalation, is respiratory failure. ? Patients should be quickly evaluated for signs of respiratory distress (e.g. cyanosis, tachypnoea, intercostal retraction, obtundation) and given oxygen. Patients with inadequate tidal volumes or poor arterial blood gases (pO2 50 mm Hg) should be intubated. ? Arrhythmias complicate some hydrocarbon ingestion and/or inhalation and electrocardiographic evidence of myocardial injury has been reported; intravenous lines and cardiac monitors should be established in obviously symptomatic patients. The lungs excrete inhaled solvents, so that hyperventilation improves clearance. ? A chest x-ray should be taken immediately after stabilisation of breathing and circulation to document aspiration and detect the presence of pneumothorax. Section 5 -FIRE FIGHTING MEASURES


¦ SMALL FIRE: ? Water spray, dry chemical or CO2 LARGE FIRE: ? Water spray or fog. FIRE FIGHTING

? Alert Fire Brigade and tell them location and nature of hazard. ? May be violently or explosively reactive. ? Wear breathing apparatus plus protective gloves. ? Prevent, by any means available, spillage from entering drains or water course. When any large container (including road and rail tankers) is involved in a fire, consider evacuation by 100 metres in all directions. FIRE/EXPLOSION HAZARD

? Liquid and vapour are flammable. ? Moderate fire hazard when exposed to heat or flame. ? Vapour forms an explosive mixture with air. ? Moderate explosion hazard when exposed to heat or flame. Combustion products include: carbon dioxide (CO2), phosphorus oxides (POx), sulfur oxides (SOx), other pyrolysis products typical of burning organic material. Contains low boiling substance: Closed containers may rupture due to pressure buildup under fire conditions. FIRE INCOMPATIBILITY

? Avoid contamination with oxidising agents i.e. nitrates, oxidising acids, chlorine bleaches, pool chlorine etc. as ignition may result. continued...

WD-40 AEROSOL Chemwatch Independent Material Safety Data Sheet Issue Date: 29-Jun-2010 CHEMWATCH 1950-6 C9317EC Version No:12 CD 2011/2 Page 3 of 7 Section 5 -FIRE FIGHTING MEASURES



Personal Protective Equipment

Breathing apparatus. Gas tight chemical resistant suit. Limit exposure duration to 1 BA set 30 mins.



? Clean up all spills immediately. ? Avoid breathing vapours and contact with skin and eyes. ? Wear protective clothing, impervious gloves and safety glasses. ? Shut off all possible sources of ignition and increase ventilation. MAJOR SPILLS

? Clear area of personnel and move upwind. ? Alert Fire Brigade and tell them location and nature of hazard. ? May be violently or explosively reactive. ? Wear breathing apparatus plus protective gloves. Personal Protective Equipment advice is contained in Section 8 of the MSDS.



? Avoid all personal contact, including inhalation. ? Wear protective clothing when risk of exposure occurs. ? Use in a well-ventilated area. ? Prevent concentration in hollows and sumps. SUITABLE CONTAINER

? Aerosol dispenser. ? Check that containers are clearly labelled. STORAGE INCOMPATIBILITY

? Avoid reaction with oxidising agents. STORAGE REQUIREMENTS

? Keep dry to avoid corrosion of cans. Corrosion may result in container perforation and internal pressure may eject contents of can. ? Store in original containers in approved flammable liquid storage area. ? DO NOT store in pits, depressions, basements or areas where vapours may be trapped. ? No smoking, naked lights, heat or ignition sources. ? Keep containers securely sealed. Contents under pressure. Section 8 -EXPOSURE CONTROLS / PERSONAL PROTECTION EXPOSURE CONTROLS Source Material TWA ppm TWA mg/m³ STEL ppm STEL mg/m³ Notes ___________ Australia Exposure Standards Australia Exposure Standards Australia Exposure Standards Australia Exposure Standards ___________ white spirit (White spirits) white spirit (Petrol (gasoline)) carbon dioxide (Carbon dioxide in coal mines) carbon dioxide (Carbon dioxide) _______

12500 5000 _______ 790 900 22500 9000 _______ 30000 30000 _______ 54000 54000 _______ (see Chapter 16) (see Chapter 16)



Chemwatch Independent Material Safety Data Sheet Issue Date: 29-Jun-2010 CHEMWATCH 1950-6 C9317EC Version No:12




?Type A-P Filter of sufficient capacity. (AS/NZS 1716 & 1715, EN

143:2000 & 149:2001, ANSI Z88 or national equivalent) EYE ¦ No special equipment for minor exposure i.e. when handling small quantities. OTHERWISE: For potentially moderate or heavy exposures: ? Safety glasses with side shields. ? NOTE: Contact lenses pose a special hazard; soft lenses may absorb irritants and ALL lenses concentrate them. HANDS/FEET

? No special equipment needed when handling small quantities. ? OTHERWISE: ? For potentially moderate exposures: ? Wear general protective gloves, eg. light weight rubber gloves. OTHER

? The clothing worn by process operators insulated from earth may develop static charges far higher (up to 100 times) than the minimum ignition energies for various flammable gas-air mixtures. This holds true for a wide range of clothing materials including cotton. ? Avoid dangerous levels of charge by ensuring a low resistivity of the surface material worn outermost. BRETHERICK: Handbook of Reactive Chemical Hazards. No special equipment needed when handling small quantities. OTHERWISE: ? Overalls. ? Skin cleansing cream. ? Eyewash unit. ? Do not spray on hot surfaces. ENGINEERING CONTROLS

¦ Engineering controls are used to remove a hazard or place a barrier between the worker and the hazard. Well-designed engineering controls can be highly effective in protecting workers and will typically be independent of worker interactions to provide this high level of protection. The basic types of engineering controls are: Process controls which involve changing the way a job activity or process is done to reduce the risk. Enclosure and/or isolation of emission source which keeps a selected hazard "physically" away from the worker and ventilation that strategically "adds" and "removes" air in the work environment. Section 9 -PHYSICAL AND CHEMICAL PROPERTIES

APPEARANCE Cloudy light amber flammable liquid with a sweet solvent odour; floats on water. Supplied as an aerosol pack. Contents under PRESSURE. Contains carbon dioxide propellant. PHYSICAL PROPERTIES Liquid. Gas. Does not mix with water. Floats on water. State Liquid Molecular Weight Not Applicable Melting Range (°C) Not Available Viscosity Not Available Boiling Range (°C) Not Available Solubility in water (g/L) Immiscible Flash Point (°C) 55 (TCC) pH (1% solution) Not Applicable Decomposition Temp (°C) Not Available pH (as supplied) Not Applicable Autoignition Temp (°C) Not Available Vapour Pressure (kPa) 724 max @21C Upper Explosive Limit (%) Not Available Specific Gravity (water=1) 0.82 Lower Explosive Limit (%) Not Available Relative Vapour Density >1 (air=1) Volatile Component (%vol) 78 Evaporation Rate Not Available Section 10 -STABILITY AND REACTIVITY CONDITIONS CONTRIBUTING TO INSTABILITY ? Elevated temperatures. continued...

WD-40 AEROSOL Chemwatch Independent Material Safety Data Sheet Issue Date: 29-Jun-2010 CHEMWATCH 1950-6 C9317EC Version No:12 CD 2011/2 Page 5 of 7 Section 10 -STABILITY AND REACTIVITY

? Presence of open flame. ? Product is considered stable. ? Hazardous polymerisation will not occur. For incompatible materials -refer to Section 7 -Handling and Storage.




¦ Irritating to skin. ¦ Repeated exposure may cause skin dryness and cracking. ¦ Vapours may cause dizziness or suffocation. ¦ Vapours may cause drowsiness and dizziness. TOXICITY AND IRRITATION


¦ Not available. Refer to individual constituents. WHITE SPIRIT: ¦ unless otherwise specified data extracted from RTECS -Register of Toxic Effects of Chemical Substances. TOXICITY IRRITATION Inhalation (human) TCLo: 600 mg/m³/8h Nil Reported Oral (rat) LD50: >5000 mg/kg Eye (human): 470 ppm/15m Inhalation (rat) LC50: >5500 mg/m³/4h Eye (rabbit): 500 mg/24h Moderate ¦ for petroleum: This product contains benzene which is known to cause acute myeloid leukaemia and n-hexane which has been shown to metabolize to compounds which are neuropathic. This product contains toluene. This product contains ethyl benzene and naphthalene from which there is evidence of tumours in rodents Carcinogenicity: Inhalation exposure to mice causes liver tumours, which are not considered relevant to humans. white spirit, as CAS RN 8052-41-3 CARCINOGEN Crude oil International Agency for Research on Cancer Group 3 (IARC) -Agents Reviewed by the IARC Monographs


This material and its container must be disposed of as hazardous waste. Ecotoxicity Ingredient WD-40 Aerosol Persistence: Water/Soil No Data Persistence: Air No Data Bioaccumulation Mobility Available Available white spirit No Data Available No Data Available


? DO NOT allow wash water from cleaning or process equipment to enter drains. ? It may be necessary to collect all wash water for treatment before disposal. ? In all cases disposal to sewer may be subject to local laws and regulations and these should be considered first. ? Where in doubt contact the responsible authority. ? Consult State Land Waste Management Authority for disposal. ? Discharge contents of damaged aerosol cans at an approved site. ? Allow small quantities to evaporate. ? DO NOT incinerate or puncture aerosol cans. continued...

WD-40 AEROSOL Chemwatch Independent Material Safety Data Sheet Issue Date: 29-Jun-2010 CHEMWATCH 1950-6 C9317EC Version No:12 CD 2011/2 Page 6 of 7 Section 14 -TRANSPORTATION INFORMATION


2YE (ADG7) ADG7: Class or Division 2.1 Subsidiary Risk: None UN No.: 1950 Packing Group: None Special Provision: 63, 190, 277, 327 Limited Quantity: See SP 277 Portable Tanks & Bulk None Portable Tanks & Bulk None Containers Containers

-Special Instruction: Provision: Packagings & IBCs PP17, PP87, L2 Packagings & IBCs P003, LP02 Packing Instruction: Special Packing Provision: Name and Description: AEROSOLS Land Transport UNDG: Class or division 2.1 Subsidiary risk: None UN No.: 1950 UN packing group: None Shipping Name:AEROSOLS Air Transport IATA: UN/ID Number: 1950 Packing Group: - Special provisions: A145 Shipping Name: AEROSOLS, FLAMMABLE Maritime Transport IMDG: IMDG Class: 2 IMDG Subrisk: SP63 UN Number: 1950 Packing Group: None EMS Number: F-D, S-U Special provisions: 63 190 277 327 344 959 Limited Quantities: See SP277 Shipping Name: AEROSOLS Section 15 -REGULATORY INFORMATION



Regulations for ingredients

white spirit (CAS: 8052-41-3) is found on the following regulatory lists;

"Australia Exposure Standards","Australia Hazardous Substances","Australia Inventory of Chemical Substances (AICS)","Australia Standard for the Uniform Scheduling of Medicines and Poisons (SUSMP)

-Appendix E (Part 2)","IMO IBC Code Chapter 17: Summary of minimum requirements","IMO Provisional Categorization of Liquid Substances -List 2: Pollutant only mixtures containing at least

99% by weight of components already assessed by IMO","International Council of Chemical Associations (ICCA) -High Production Volume List"

No data for WD-40 Aerosol (CW: 1950-6)



Ingredient Name CAS isoparaffins petroleum hydrotreated 64742-47-8, 64742-82-1, 8052-41-3,

1030262-12-4, HFP 101795-05-5 ¦ Classification of the preparation and its individual components has drawn on official and authoritative sources as well as continued...

WD-40 AEROSOL Chemwatch Independent Material Safety Data Sheet Issue Date: 29-Jun-2010 CHEMWATCH 1950-6 C9317EC Version No:12 CD 2011/2 Page 7 of 7 Section 16 -OTHER INFORMATION

independent review by the Chemwatch Classification committee using available literature references. A list of reference resources used to assist the committee may be found at:

formatting link

¦ The (M)SDS is a Hazard Communication tool and should be used to assist in the Risk Assessment. Many factors determine whether the reported Hazards are Risks in the workplace or other settings. This document is copyright. Apart from any fair dealing for the purposes of private study, research, review or criticism, as permitted under the Copyright Act, no part may be reproduced by any process without written permission from CHEMWATCH. TEL (+61 3) 9572 4700.

Issue Date: 29-Jun-2010 Print Date: 28-Jul-2011

This is the end of the MSDS.

Reply to
Michael A. Terrell


You want to use DeOxit.


Phil Hobbs

Dr Philip C D Hobbs 
Principal Consultant 
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Reply to
Phil Hobbs

My ultrasonic cleaner gets used at least once a week to clean the business end of my electric shaver. that's not the only use either.

It came with an assortment of attachments for cleaning CDs and a watch bracelet holder amongst others.

Reply to
Ian Field




Yes, I think you are right. I disconnected the cap and connected an ohmmeter across the plates and read many points of low resistance. So, I soaked the cap in a cup of isopropy rubbing alcohol and rotated the plates every few minutes and dried it out in the sun and then applied a few drops of sewing machine oil and it seems ok now. I found someone who has a ultrasonic cleaner to loan and will try it out next week.


Reply to
Bill Bowden

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