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 Post subject: BC-342 How to clean the tuner gearing
PostPosted: Jan Mon 04, 2021 10:09 pm 
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Location: Dandridge, TN 37725
I have a BC-342 (OA-65A / MRC-2) Channel A Receiver on the bench - a repair job believe it or not. This thing is a TRUE mess. The gearing in the tuner, and everything else is filthy. I suppose that the gearing has to come out, for proper cleaning, right? Does that mean that the front panel has to be removed? None of the manuals I have read address that level of disassembly. The radio appears to be original. I see no signs of component replacement. Here's what greeting me when the radio was removed from the cabinet.
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The radio was apparently re-purposed and used as a field radio in Korea. It has seen some rough handling. The Crystal Phasing knob is missing and the shaft broken off flush with the panel. I have restored many tough dogs (such as Philco Predicta and Emerson 639 TV sets and RCA 140 Radios, but nothing like this. Any suggestions (other than to refuse the job)?

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 Post subject: Re: BC-342 How to clean the tuner gearing
PostPosted: Jan Mon 04, 2021 10:32 pm 
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when you say job it implies doing something for money for someone else.if someone else is HAPPY to pay you with NO guarantee of a specific outcome and you feel comfortable with that arrangement then sure,if you have the time,are interested in the challenge then why not? if no to any of the above then walk away.break out the vacuum cleaner and see what you got.


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 Post subject: Re: BC-342 How to clean the tuner gearing
PostPosted: Jan Mon 04, 2021 11:13 pm 
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Location: Dandridge, TN 37725
The owner wants the radio to work (his father used it in Korea) and knows it will be expensive. I have read and seen YouTube videos on replacing capacitors, resistors, alignment, etc. That part of the job I feel I can handle on this radio. The big issue to me is that the tuner gears have to be cleaned. One can hardly move the tuning knobs. Can that be done without total or partial disassembly? Has anyone done this and has experience? I do not want to start taking things apart without some guidance.

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 Post subject: Re: BC-342 How to clean the tuner gearing
PostPosted: Jan Tue 05, 2021 12:07 am 
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Location: Liberty, Missouri
My advise would be to use a pressure washer to clean that radio up, just remove the tubes. If you don't have a pressure washer you can go to the local DIY car wash.

I do this often with dirty boat anchors. I usually do it in groups, then leave them to soak in the hot sun, standing on one end or the other for a couple days, on up-ended trash cans or the patio table. This allows air to easily circulate throughout the chassis and the heat helps accelerate evaporation.

This method is very thorough and quick. I make sure I give each tube socket, connector, gear, especially those split spring loaded types, and open bearing, a good squirt. Often the result is that the chassis looks virtually brand new. I enjoy working on these things but I don't like getting myself and the bench nasty dirty in the process. Let alone all the paper towels etcetera.

Here are some examples of before/after on a few radios. None of these took more than 5 minutes under the gun. :wink:

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Image

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ClickThePIC

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 Post subject: Re: BC-342 How to clean the tuner gearing
PostPosted: Jan Tue 05, 2021 1:33 am 
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What type of cleaner/etc would I use other than water? I do have a pressure washer. I will looks at the comments - but you obviously have done this before. Thanks!

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 Post subject: Re: BC-342 How to clean the tuner gearing
PostPosted: Jan Tue 05, 2021 4:21 am 
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I just use the "regular" soap sold for pressure washers.

Once you have finished the wash, rinse with a couple gallons of distilled water from the grocery. The rinse is to displace the house water contaminates. Then if you have compressed air or a leaf blower, blow off what excess water you can, then let it dry in the sun if possible.

I've done this on bout ten really dirty radios 7 of which are done and operating, the rest are in the Queue. This really shortens the process.

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 Post subject: Re: BC-342 How to clean the tuner gearing
PostPosted: Jan Tue 05, 2021 5:50 am 
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Judging from the second photo... you just may have a rare variant power supply that also had a voltage regulator tube.
There power supplys were used in diversity receivers that is two receivers were employed with two antennas to combat fading


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 Post subject: Re: BC-342 How to clean the tuner gearing
PostPosted: Jan Tue 05, 2021 2:40 pm 
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I'd clean it up then decide if it's worth it. I've worked on quite a few of these, and they are not rare. For example, I was going to work on a BC-314 that was rough and asked around for a parts set. The parts set I found was a much better example, and the original set became the parts set.

I think they tend not to move around much because of their weight, and expense of shipping can keep online buyers away.
Taking off the faceplate (and putting it back on correctly) is not an easy job.

There are parts of these that are awesome, like the lift-off-the-top IF covers, and other parts are pure hell like replacing the antenna relay.

Clean it up, then test the coils, transformers and look for any weird mods, and corrosion.
I hope you're charging enough!

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 Post subject: Re: BC-342 How to clean the tuner gearing
PostPosted: Jan Tue 05, 2021 3:26 pm 
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Instrument Fixer wrote:
Judging from the second photo... you just may have a rare variant power supply that also had a voltage regulator tube.
There power supplys were used in diversity receivers that is two receivers were employed with two antennas to combat fading

You are correct - this radio is Channel A of Radio Receiver Assembly OA-65A/MRC-2 consisting of an oscillator coupling amplifier and two receivers which are modified versions of Radio Receiver BC-342. We assume that it was repurposed as a field radio.

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 Post subject: Re: BC-342 How to clean the tuner gearing
PostPosted: Jan Tue 05, 2021 6:43 pm 
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My National HRO was just about as bad! I have never had the nerve to use a pressure washer on a piece of electrical gear, before. The HRO was so bad, that I figured I didn't have much to loose. Taking Mikes recommendation to power wash, seemed like the best option. I removed it from the cabinet, removed the tuning capacitor, for access, and taped plastic bags over and around the IF transformers. Took it outside and hit it with the washer. Now I wish I had removed the IF transformers, as well, because I ended up removing them anyway. I had no issues with water getting into them, I should add. Since then, I have done this to a couple of radios that were very dirty. I just try to keep the water out of the transformers, and let them dry in the sun. I do hit them with the leaf blower or compressed air hose, before letting them sit in the sun.

Kind of scary, but it does work.

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 Post subject: Re: BC-342 How to clean the tuner gearing
PostPosted: Jan Tue 05, 2021 9:37 pm 
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Hmm. Who thinks a pressure washer will help this out?


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 Post subject: Re: BC-342 How to clean the tuner gearing
PostPosted: Jan Tue 05, 2021 10:36 pm 
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aw heck spray a little Simple Green on that and itā€™ll look like new

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 Post subject: Re: BC-342 How to clean the tuner gearing
PostPosted: Jan Wed 06, 2021 12:58 am 
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Yep, just needs a little work.

John


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 Post subject: Re: BC-342 How to clean the tuner gearing
PostPosted: Jan Wed 06, 2021 1:24 am 
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Hi Chris,
I just put a little piece of masking taps over the adjustment holes in the IF cans, that way I can do a better job at their bases. I usually don't do much to the underside of a radio unless its pretty bad. I did the underside of one of my AR-88s because it apparently had a filter cap go bad and cook one of the PS chokes. I even went so far as to use auto parts washer solvent to clean up the area.

The underside was fairly grungy over so I gave it a fairly quick douche and it turned out immaculate, for the most part. Pretty good lookin for about 80 years old.

Image

Image

The other one isn't nearly as nice looking but still much better than when I got it, and I have yet to start on it.


Hi Jim,
The pressure washer won't do anything for the rust, but most everything else will look pretty new. If nothing else you'll have clean parts and knobs for the junk box. :wink:

Seriously though, That is pretty far gone, so I think you'd have nothing to loose, giving it a try.

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Last edited by Mikeinkcmo on Jan Wed 06, 2021 1:57 am, edited 1 time in total.

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 Post subject: Re: BC-342 How to clean the tuner gearing
PostPosted: Jan Wed 06, 2021 1:40 am 
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Well, I did it (pressure washing) but I did not get a lot of sleep last night. I used Crud Buster for the cleaning solution (no bleach or ammonia) - alkaline. The tuning mechanism now works freely. I had to go over the large gears afterward with a gun cleaning toothbrush to remove any remaining crud. Now comes the problem of drying it out without any sunlight! Then lubrication. At least the manual covers that. I am betting that the gears with the springs between rotating members still do not work correctly. But my customer will likely not object to a little backlash. He just wants it to work. Thanks for the tips and discussion. Now I have to find that missing CRYSTAL PHASING knob. I doubt that my usual radio/TV knob vendors will help this time.

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 Post subject: Re: BC-342 How to clean the tuner gearing
PostPosted: Jan Wed 06, 2021 2:47 am 
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Hi Dave,
My first Victim was my Gonset GS-100 a few years ago. It had a bad power transformer, from a previous owner. It was fairly dirty, and even though the weather was fairly cold I washed it anyway.
Image

I used one of those high Watt, high intensity work/flood lights from Harbor Freight to dry it. I did what you see in the pic, one end first, then, turned it end for end, then rotated bottom to top, and did one end of the top side, again swapping that, end for end. I took 4 days to do the entire process but it WAS DRY. For me, just like you, it was a NEW adventure. I then spent another week or so checking/replacing demonstratable bad parts, before firing it up for the alignment.

=====
Does the crystal phasing knob have a skirt? I presume the styling is similar to what I can see of the other knobs, I have a few knobs and maybe I have something that might do. If I have it, its yours for postage, worst case.

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Last edited by Mikeinkcmo on Jan Wed 06, 2021 4:24 am, edited 1 time in total.

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 Post subject: Re: BC-342 How to clean the tuner gearing
PostPosted: Jan Wed 06, 2021 4:18 am 
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Quote:
Now I have to find that missing CRYSTAL PHASING knob

Did you post in the classifieds?

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 Post subject: Re: BC-342 How to clean the tuner gearing
PostPosted: Jan Wed 06, 2021 6:31 am 
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Joined: Aug Wed 14, 2019 6:56 am
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Location: angeles city.philippines,2009
the anti-backlash gears can be separated with no damage by using an xacto knife blade to work a gap all around.using a syringe you can inject the cleaning solvent of your choice on my sx42 i did this after i figured it was dry i lubed the interface with dot5 silicon brake fluid as it was the only silicon oil i had.the idea being to put something in there to prevent any corrosion while at the same time cant gum up as it drys up


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 Post subject: Re: BC-342 How to clean the tuner gearing
PostPosted: Jan Wed 06, 2021 11:58 am 
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The pressure washing method is great for bad cases but you need to be mindful of anything paper, mostly chokes and transformers that aren't potted. Iron with end bells doesn't count. It must be either removed or covered somehow.


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 Post subject: Re: BC-342 How to clean the tuner gearing
PostPosted: Jan Wed 06, 2021 1:12 pm 
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Quote:
...the anti-backlash gears can be separated with no damage by using an xacto knife blade to work a gap all around, then, using a syringe you can inject the cleaning solvent of your choice....i lubed the interface with dot5 silicon brake fluid....to prevent any corrosion..

An exacto or box knife blade is the right tool there, and I do the same sort of thing for injecting solvent between the plates. Be sure to put some paper towels under the bottom of the gears to catch the dirty run off. However, I don't put any sort of liquid inhibitor or lubricant between the plates.

Unless the radio is in some particularly damp or salty marine location there won't be any corrosion. Those gear plates don't really move more than perhaps a thousandth of an inch or two at most, the movement depends entirely on how well the meshing brass gear was machined or broached, so lubricating properties aren't an issue. When assembled new those hard aluminum plates were clean and dry, and possibly Anodized, the drive gears were most often brass which really doesn't need any lubricant in that type of application.
=====
Quote:
...The pressure washing method is great for bad cases but you need to be mindful of anything paper, mostly chokes and transformers that aren't potted. Iron with end bells doesn't count. It must be either removed or covered somehow...


Pretty good advise but now I do it in most cases, I just don't want to waste all the hours doing the job by traditional methods. I agree with the paper, and covering open frame transformers, and as I mentioned earlier covering the adjusting holes in I.F. cans with bits of masking tape, and removing meters and tubes, but end bell style transformers are fine as is, I just make an effort not to fill them up, if I wash the under chassis area. Usually that area is pretty clean anyway.

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