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eHam Forums => Boat Anchors => Topic started by: N6QWP on February 07, 2019, 11:03:15 AM



Title: CLEANING UP VARIABLE CAPS IN DIRTY OLD AMPLIFIERS?
Post by: N6QWP on February 07, 2019, 11:03:15 AM
Seeking input on what to use on another old amplifier (Collins 30L-1) that is very dirty.  Have used KrudKutter in the past, but found that the variable capacitors seemed to discolor and even corrode somewhat over time after having been sprayed, rinsed and dried.

While the KrudKutter worked very well on most of the amps and other radios, wondering if there is a better spray of some kind that does not require rinsing with water when finished-especially for the caps....OR....a product to follow up with (immediately afterwards)?

Since there is high voltage and the risk of arcing on the variable caps in an amplifier, I would like to find a proven product that will rid the surfaces of any crud, nicotine and anything else that contaminates....and hopefully leaves them as new.

Something that could follow the normal use of KrudKutter and rinse (to eliminate the problems of air and water on the plates) would probably be ideal.....as when first cleaned with the KrudKutter, the results seem great.  

This time of year, it is very difficult to properly dry out a rig that has been rinsed with water.  No hot sunny days to help.

Automotive sprays, or electronic sprays (by name)?


Title: RE: CLEANING UP VARIABLE CAPS IN DIRTY OLD AMPLIFIERS?
Post by: G3RZP on February 07, 2019, 02:01:43 PM
In the days of analogue VFOs, some people found that an ultrasonic cleaner really worked well, although you have to physically remove the cap and re-lubricate the bearings afterwards. I figure that would work well with the 30L1 capacitors, although I know from experience it's a bit of a PITA getting them out.


Title: RE: CLEANING UP VARIABLE CAPS IN DIRTY OLD AMPLIFIERS?
Post by: WB4SPT on February 07, 2019, 02:12:21 PM
3M electronic cleaner aerosol.   At $25 a can, don't waste it! No residue, no water, plastics safe. 


Title: RE: CLEANING UP VARIABLE CAPS IN DIRTY OLD AMPLIFIERS?
Post by: N6QWP on February 07, 2019, 02:20:49 PM
Thanx Peter....I am trying to find something that works.....and does not require that the amp be dismantled.  I have already taken one apart.....don't want to do that again.

Looking for a "Spray and Rinse" type of cleaner that doesn't encourage corrosion.

An "After Rinse" type of flush for the variables is what I am hoping someone has found that works well.  Some product that replaces any moisture....and lubes the plates.....WITHOUT leaving any residue to attract further dirt or dust.
------------------------------------------------------------------------------

While I was typing, WB4SPT suggested the 3M product.  Thanx for that.  

David, would you use that "After the KrudKutter scenario"......OR....instead of?  I will be using the KrudKutter for the rest of the amp's insides, and will invariably get water onto the caps' plates.
-------------------------------------------------------------------------------

Would like to find a similar product that is available at about half of that cost.  I have four of these "Old Dogs" and would like to clean them (or "recondition" those that have already been sprayed) at a lesser expense.    

Any further ideas???

Ideally, some product that would also "Restore" the capacitor plates on those amps that have already been exposed to the ravages of spraying and rinsing (and show slight signs of corrosion).  This might have to be a different product???









Title: RE: CLEANING UP VARIABLE CAPS IN DIRTY OLD AMPLIFIERS?
Post by: WB4SPT on February 07, 2019, 04:34:20 PM
I have used krud kutter. It is very effective on smoking tar.  If that is in the plan, i see no need for an expensive spray.  But u dont want much of anything to sit on capacitor plates for long. I use a hot water rinse immediately followed by compressed air blow off. Then a long warm bake cycle. 

My 3m answer would be only for a targeted strike on the cap. 73’s


Title: RE: CLEANING UP VARIABLE CAPS IN DIRTY OLD AMPLIFIERS?
Post by: N6QWP on February 07, 2019, 05:14:20 PM
Thanx for that Peter.....I am still looking for an inexpensive replacement for the 3M spray.  Unfortunately, with winter here, I don't have the facilities to properly dry the caps (or the entire amp itself) after the bath.

While I can blow off the rinse water with a small compressor, I don't want to put the entire amp into the gas oven.  Perhaps I will have to wait until the late spring for warmer weather....when, on a nice warm day, I can let the top of the amp chassis sit in direct sunshine.

I am still looking for a chemical spray to "cure" the caps after they have been subjected to both the KrudKutter and the water rinse.  I want something that, as said earlier, will coat and protect the capacitor plates from oxidation.....without leaving a film that will attract dust and dirt.

Anyone have any experience with some of the AUTOMOTIVE SPRAYS (available at most automotive parts stores)?


Title: RE: CLEANING UP VARIABLE CAPS IN DIRTY OLD AMPLIFIERS?
Post by: N4MQ on February 07, 2019, 06:07:54 PM
Dont forget that pipe cleaners work in the plate areas. Woody Enjoy


Title: RE: CLEANING UP VARIABLE CAPS IN DIRTY OLD AMPLIFIERS?
Post by: W9IQ on February 07, 2019, 06:26:08 PM
Quote
I am still looking for a chemical spray to "cure" the caps after they have been subjected to both the KrudKutter and the water rinse.  I want something that, as said earlier, will coat and protect the capacitor plates from oxidation.....without leaving a film that will attract dust and dirt.

Keep in mind that any coating will act as a dielectric with a relative permittivity > 1. This will raise the minimum and maximum capacitance which may affect your usuable tuning range.

You will also need to take care not to coat the wiper or bearing areas as this could render it useless.

- Glenn W9IQ


Title: RE: CLEANING UP VARIABLE CAPS IN DIRTY OLD AMPLIFIERS?
Post by: KE0ZU on February 07, 2019, 09:35:05 PM
I used Ammonia and a 1" paint brush to clean this one, and it worked pretty well.  But it took three hours or so to do it.  

Here's before...
(https://photos.smugmug.com/HAMMARLLUND/HQ-170/i-nrHsvqx/0/d9204425/L/DSC_1680-L.jpg) (https://mikeharrison.smugmug.com/HAMMARLLUND)

And here's after.   Not too bad considering.
(https://photos.smugmug.com/HAMMARLLUND/HQ-170/i-Fbv9TjZ/0/e0b3112b/L/P4300002-L.jpg) (https://mikeharrison.smugmug.com/HAMMARLLUND/HQ-170/i-Q4Hsh5s/A)

(https://photos.smugmug.com/HAMMARLLUND/HQ-170/i-Q4Hsh5s/0/ff4f9fad/L/P6010007-L.jpg)


--------

Here is another example of a cleaned chassis.   This time I experimented with a new and different method.

Looking at the variable capacitor in the second picture, you can see its spotless.   It does the same for any variable cap I've encountered.

Here is before...
(https://photos.smugmug.com/NATIONAL/NC240D/B4-the-bath/i-CS8RJdZ/0/d6c59b7e/XL/B4%202-XL.jpg) (https://mikeharrison.smugmug.com/NATIONAL)

And this is after the bath.
(https://photos.smugmug.com/NATIONAL/NC240D/After-the-bath/i-ZQXBXTd/0/e4ddc1aa/L/DSC_2470-L.jpg) (https://mikeharrison.smugmug.com/NATIONAL/NC240D/After-the-bath/i-DsCq6bM/A)

This one took about 5 minutes.   I used a pressure washer and the typical "soap" they sell to use in them.  

(https://photos.smugmug.com/The-Shack/Ranger2-40-D/i-B3HZ8MG/0/7ff4428c/L/P2220025-L.jpg)

After I did this and saw how it came out, I pulled a few more out of the queue and did them as well.   Again the big variable capacitors came out looking absolutely new.   This Viking II looked easily as dirty and nasty as the receiver above, but you would never know it, by the way it looks now. 

(https://photos.smugmug.com/EF-JOHNSON/Viking/i-B7d3sqc/0/b92e8a0d/L/V2%20PressureWash-L.jpg)

This poor HT37 example has a badly pitted chassis so it's just going to be a driver, with no attempt to any more cosmetics.
(https://photos.smugmug.com/HALLICRAFTERS/HT-37/i-c3NLQSb/0/5467f905/L/DSC_2229-L.jpg)

I rinsed all with distilled water, blew them out with an air hose, and sat them in the sun for a couple days.   This saves several hours work each, and the results are equally as good.

Now I know whats "next" is already clean, which makes a big difference.


 


Title: RE: CLEANING UP VARIABLE CAPS IN DIRTY OLD AMPLIFIERS?
Post by: AC5UP on February 08, 2019, 03:18:16 AM
Two concepts to chassis cleaning come to mind...

On a lightly soiled chassis wipe out as much gunk as possible with diluted 409 type cleaner and give it soak time between wipings.  Mild cleaner / maximum working time / minimum surface damage.

For a more difficult level of gunk, especially if there's any oiliness about it, I'd try a bit of auto carburetor cleaner on a cotton pad in an obscure part of the chassis as a test.  If it works well, do the rest and consider a follow-up with a mild household cleaner to encourage a zero-residue job.


Title: RE: CLEANING UP VARIABLE CAPS IN DIRTY OLD AMPLIFIERS?
Post by: N4MQ on February 08, 2019, 04:09:55 AM
I have used a pressure washer also, with care and at a moderate distance.  Avoid dials, paper components, as they can be trashed easily if your not paying close attention.  This was done in the heat of the summer and allowed to dry in the sun for several days without issue. Enjoy Woody


Title: RE: CLEANING UP VARIABLE CAPS IN DIRTY OLD AMPLIFIERS?
Post by: N6QWP on February 08, 2019, 07:18:51 AM
Looks like I will have to wait until summer to get this one really cleaned up inside.  Nice job Mike.

Anyone try the various "hot" spray chemicals like brake cleaner, carb cleaner or other automotive types on variable caps???  Worrying about if some could be "too hot" for surrounding components and knobs or lettering on front panel???  Residue???  Warnings???

Will have to postpone using water rinses until a time when we once again have hot sunshine that will help with the drying.  Thanx for the input so far.


Title: RE: CLEANING UP VARIABLE CAPS IN DIRTY OLD AMPLIFIERS?
Post by: KD0REQ on February 08, 2019, 08:09:50 AM
brake cleaner, etc. will absolutely devastate plastics.

isopropyl alcohol has been my go-to for years... but seeing how household ammonia has done some small jobs, I'm using it more.  you will have to relubricate after any severe cleaning, and neutralizing with either iso or distilled water.


Title: RE: CLEANING UP VARIABLE CAPS IN DIRTY OLD AMPLIFIERS?
Post by: N6QWP on February 08, 2019, 04:38:41 PM
Will definitely have to wait for hot weather to flush the insides of amp using water, after cleaning it.  Today, I removed and sprayed and cleaned the outside cabinet (which was really filthy and scratched.  After using a used green pad to dislodge the many layers of dirt, I flushed the whole cabinet inside and out with cold water from the outside hose.

Even after wiping it down, shaking it and bringing it inside to a warm environment, it still has lots of water trapped in the many holes in the cabinet.  This is definitely not the time to use any water on a cleaning project.  Am planning on sanding and spray painting the entire cabinet and ring as soon as the temperature gets back to warm enough levels for the paint to set up properly.

I might just try some ammonia and rubbing alcohol, after the rain stops....to see what they can accomplish on the chassis and many components.  If that seems to do a good job, I might resort to using the KrudKutter and following it up with flushing using those products instead of water.  Will definitely have to use a hair dryer to thoroughly dry out the chassis and parts.

If I can get some feedback on an automotive chemical cleaner that will not leave any residue, I can restrict it's use to just the two variable capacitors and the band coil (without subjecting any of the panel or knobs or meter to it's harsh effects).


Title: RE: CLEANING UP VARIABLE CAPS IN DIRTY OLD AMPLIFIERS?
Post by: AC5UP on February 08, 2019, 08:24:11 PM
No need to wait until summer...  Is there any place in the house where you can park it for a day or two near a heating register?  For small items I've had excellent luck with the warm spot above the pilot light of a gas range.  30 minutes or so and it's dry.

Ammonia is inexpensive almost anywhere.  At my local home & ranch supply store a gallon of white ammonia (or vinegar) can be had for $3.00 or so and a gallon goes a long way.  Rare that I use it straight, for cleaning a 50 / 50 cut seems about right.  If you have water stains you can ease them out with vinegar if allowed to soak for a few hours.  Check and agitate the part a few times during the process.  And while you have the bottle open run a cup or two of a 50 / 50 mix through your coffee maker.

As mentioned above, brake or automotive electronics cleaner will damage plastics so I recommend carbuerator cleaner instead.  Spray into a cotton cosmetic pad and use the pad as a wipe-on instead of a direct spray.


Title: RE: CLEANING UP VARIABLE CAPS IN DIRTY OLD AMPLIFIERS?
Post by: WB4SPT on February 09, 2019, 10:42:12 AM
You want to keep aqueous ammonia away from bare copper, though, correct?


Title: RE: CLEANING UP VARIABLE CAPS IN DIRTY OLD AMPLIFIERS?
Post by: W9IQ on February 09, 2019, 10:59:32 AM
You want to keep aqueous ammonia away from bare copper, though, correct?

Correct. Stoichiometric quantities of aqueous ammonia will react with copper, zinc, and brass.

In the case of copper, initially copper hydroxide will form as indicated by a light blue color. Further reaction with the ammonia solution will cause deep blue ammoniacal copper solution to form.

- Glenn W9IQ


Title: RE: CLEANING UP VARIABLE CAPS IN DIRTY OLD AMPLIFIERS?
Post by: N6QWP on February 09, 2019, 01:36:14 PM
Thanx for the heads up on using ammonia.  Will seek another venue.  The band coil would be vulnerable......as would the large choke and some wiring.

Guess I am back to KrudKutter and perhaps rubbing alcohol or carb spray to flush?

Does carburetor cleaner spray leave any kind of residue???  What about starting fluid?  (Both are cheap).


Title: RE: CLEANING UP VARIABLE CAPS IN DIRTY OLD AMPLIFIERS?
Post by: AC5UP on February 09, 2019, 02:16:36 PM
Does carburetor cleaner spray leave any kind of residue???  What about starting fluid?  (Both are cheap).

Carburetor cleaner may leave a slightly oily residue as it does contain petroleum distillates but nothing heavy enough to attract dust.  About the same as WD-40 after being wiped off, which does dry completely over time.  Read the label on starting fluid and I think you'll find it's mostly denatured alcohol.  If so, you can get a better price per ounce at the local big box hardware store in the paint section.  Quart can.

Which makes me wonder if turpentine might be worthwhile as a chassis cleaner...


Title: RE: CLEANING UP VARIABLE CAPS IN DIRTY OLD AMPLIFIERS?
Post by: G3RZP on February 11, 2019, 04:37:30 AM
Can you get genuine turpentine in the US? Over here, it's all an artificial 'turps substitute'.


Title: RE: CLEANING UP VARIABLE CAPS IN DIRTY OLD AMPLIFIERS?
Post by: LA9XNA on February 11, 2019, 01:00:21 PM
For chassis components and mechanical bits try washing  with hot water and wash-up liquid.
This will remove all grease on the parts.
In case you have an old dish washer not in use, spray the parts in a mix of water and wash-up liquid (mix 1-10) and let it soak for 5-10 minutes.
Stick it in the dish-washer on low temp and short time program. Be sure to dry it properly with an air nossle and hair dryer/heat gun, but be aware of the temperarure on painted componets because heat can damage the paint.

For smaller mechanical parts like switches and variable capacitors you can use an ultrasonic cleaner with water and wash-up liquid until all the dirt is gone.
(https://media.killerinktattoo.no/media/catalog/product/cache/10/thumbnail/125x/05eaf0853a2c2bdf6d80a6b137b24638/u/l/ultra-7000s-uk_1.jpg)
After the parts are cleaned, rinse off the part in fresh water and use a compressed air nossle to remove most of the water.
Then empry the tray on the ultrasonic and use alcohole (NO HEATER ON THE ULTRASONIC) And let the part sit for a few minutes.
The alcohole will remove the water from the part even in the small cracks.

Oil moving parts as required for good operations.


Title: RE: CLEANING UP VARIABLE CAPS IN DIRTY OLD AMPLIFIERS?
Post by: N0MKC on February 11, 2019, 02:54:30 PM
So far as drying it out after cleaning...   

Hair dryer?  Somewhat labor-intensive, but should speed the drying process quite a bit, and no need to wait for warm, sunny weather.

(I'm kinda surprised it hasn't been mentioned yet...)


Title: RE: CLEANING UP VARIABLE CAPS IN DIRTY OLD AMPLIFIERS?
Post by: N3DT on February 11, 2019, 02:56:12 PM
Forget about the carb cleaner, starting fluid or similar products. They're far too risky on non-metallic parts. WD40 is not bad, it eventually evaporates and can be cleaned up with alcohol. But WD40 will also remove a lot of inked data, so be very careful where you put it. I doubt there's any magic solution. I like the ammonia but would also be careful where to use it and would wash it off also with alcohol/distilled water. No matter what you use, there is going to be some amount of care involved with brushes and rags. Distilled water wash is not bad, but does not remove a lot of grime and may also get into things. Need compressed air or heat to remove it, consider even careful use of a heat gun or hair dryer. WD40 on a rag or brush is my favorite followed by denatured alcohol and some sort of compressed air. Some small shop type vacs can be reversed and are not too brutal. I have a small $25 reversible shop vac that's about ideal for blowing not stiff air and I use it to blow out my computers too.


Title: RE: CLEANING UP VARIABLE CAPS IN DIRTY OLD AMPLIFIERS?
Post by: N4NYY on February 11, 2019, 04:23:29 PM
Seeking input on what to use on another old amplifier (Collins 30L-1) that is very dirty.  Have used KrudKutter in the past, but found that the variable capacitors seemed to discolor and even corrode somewhat over time after having been sprayed, rinsed and dried.

While the KrudKutter worked very well on most of the amps and other radios, wondering if there is a better spray of some kind that does not require rinsing with water when finished-especially for the caps....OR....a product to follow up with (immediately afterwards)?

Since there is high voltage and the risk of arcing on the variable caps in an amplifier, I would like to find a proven product that will rid the surfaces of any crud, nicotine and anything else that contaminates....and hopefully leaves them as new.

Something that could follow the normal use of KrudKutter and rinse (to eliminate the problems of air and water on the plates) would probably be ideal.....as when first cleaned with the KrudKutter, the results seem great.  

This time of year, it is very difficult to properly dry out a rig that has been rinsed with water.  No hot sunny days to help.

Automotive sprays, or electronic sprays (by name)?

I have used the Krud Kutter and I was one of the first to champion it here for restorations. I have used it on variable caps, but only on radios and it worked great. One of the few products that gets rid of all the nicotine. Saying that, I have never used it on an amp and the voltages associated with it.

If I have done it in winter, I would blow it out with a compressor and park it over a hot air heating vent for a day or 2.


Title: RE: CLEANING UP VARIABLE CAPS IN DIRTY OLD AMPLIFIERS?
Post by: N6QWP on February 11, 2019, 05:24:59 PM
Well, being bored today, I decided to take a chance and try to clean up this old 30L-1 amp using KrudKutter and boiling water and CRC QD Contact Cleaner....before the upcoming storm hits.

While cold (50's), the KrudKutter did dislodge all kinds of dirt.  Flushed it with boiling (almost) water.  After a while, (I could see the surfaces were getting that "salty finish"), I took amp back outside and hit the caps with CRC QD Contact Cleaner.

Looks like I will have to scrub any surface that I want to shine.  The spray is not supposed to leave any residue, but the surfaces showed a distinct dull finish....that if I took my finger, I could remove......this on all the areas of the variable caps and elsewhere on some of the chassis and obvious (previously) shiny surfaces.

I guess that there is no way, short of hitting all of the surfaces with some kind of rubbing action, I will be able to get anything like a new finish.

The question now, is whether there will be any tendency to arc between these oxidized surfaces at high voltage under hi power (500-700 watts).

I have noticed this effect on four different 30L-1 amps after the flushings.  Have only had a flashover on one of them so far.....but believe that was due to a faulty tube.  Time will tell.

Would like to hear from anyone who has tried cleaning similar amps using similar products.

Amp is presently in front a 1500 watt heater, getting a good drying out.  I might have to go back and hit everything again.....the surfaces on the white porcelain high voltage cap and some insulators still are not totally clean.  Will decide later.....and do it on a warmer day, if necessary.



Title: RE: CLEANING UP VARIABLE CAPS IN DIRTY OLD AMPLIFIERS?
Post by: N4NYY on February 11, 2019, 06:14:43 PM
I have not had that "salty" residue on the variable caps that I did. They came out looking new.

However, it interacted with some metals. I would see this effect on screws or some chassis. But I never had it happen on variable caps.

The only other issue I had was on silkscreen paint over shiny aluminum. The paint just came right off. It did not affect painted steel or silkscreening over painted surfaces. It works great on plastic.

BTW, when I used Krud Kutter, I only leave it on for about 1-2 min, then flushed it with cool water. I never used boiling water.


Title: RE: CLEANING UP VARIABLE CAPS IN DIRTY OLD AMPLIFIERS?
Post by: N4NYY on February 11, 2019, 06:28:50 PM
I did some quick googling and the white power may be Cadmium Oxide. It appears to be toxic and common on old equipment (I'm not familiar with it). Depending on where you google, they will tell you to stay the hell away, or not to worry about it. There were several methods to cleaning it, but I will leave that to the experts. I would take precautions just to be safe.


Title: RE: CLEANING UP VARIABLE CAPS IN DIRTY OLD AMPLIFIERS?
Post by: N6QWP on February 13, 2019, 09:11:36 AM
After looking up cadmium oxide, it seemed that it would be brown in color.....not the powdery white or gray.  It appears to be simple oxidation....or residue from the water or spray on certain surfaces?



Title: RE: CLEANING UP VARIABLE CAPS IN DIRTY OLD AMPLIFIERS?
Post by: N4NYY on February 13, 2019, 03:25:32 PM
After looking up cadmium oxide, it seemed that it would be brown in color.....not the powdery white or gray.  It appears to be simple oxidation....or residue from the water or spray on certain surfaces?



Try some naval jelly on a spot and after like 30 sec, rinse it off. If that works, use it. I have used naval jelly on chassis oxidation, but never a variable cap.


Title: RE: CLEANING UP VARIABLE CAPS IN DIRTY OLD AMPLIFIERS?
Post by: N6QWP on February 14, 2019, 09:46:02 AM
Thanx I'll give that a try when the storms finish up here.


Title: RE: CLEANING UP VARIABLE CAPS IN DIRTY OLD AMPLIFIERS?
Post by: WB4SPT on February 15, 2019, 03:40:09 PM
Thanx I'll give that a try when the storms finish up here.

On the KK routine.   I did not do the first rinse with this super hot water.   It is possible that when you bring up the KK coated part temperature up 150 degrees, it becomes much more reactive.  Heat increases reactivity of most any chemical reaction.   You don't want chemical reactions, you just want the surfactants to work. 
The hot water is the last rinse step.   After all the chemicals are already washed off the unit. The hot water simply aids evaporation. 
BUT, any aluminum oxide that may have formed, will be electrically inert as far as conductivity. 


Title: RE: CLEANING UP VARIABLE CAPS IN DIRTY OLD AMPLIFIERS?
Post by: KA4KOE on February 16, 2019, 02:12:28 PM
One cleaning solution I heard of was a 50/50 mix of ammonia and 409. I used it on my R388 chassis and it cleaned right up. Be careful, however.