51J-4 disassembly questions

[ka8wfc]

Hi folks,

I found a 51J-4 project... The mechanical filter (bandwidth) switch and the crystal filter switches are very stiff--so much so that I'm concerned they'll break if I try to force them--so need to disassemble the radio enough to uncover the switches, clean and treat with Deoxit, etc.

Any hints on how much disassembly I'll need to do to get them off?

I've got the panel off and it still looks fairly daunting. I haven't found a mechanical drawing showing how all of the housing and assemblies go together, so suppose I'll just keep taking things apart until I gain access. Hopefully that won't require removing the MC dial and PTO, but maybe?

TNX and 73, Chris W1XG

[WB4AM]

Hello Chris,

No experience here working on these but, I am attaching a link to the manual.
There is a little info on cleaning on page 5-1.

They really just mention "jet air". 
Maybe try this to start and then using one of those plastic straws attached to a small can of WD40
might get in between the mechanical parts and loosing things up.  Then maybe follow up with some Deoxit D5.

Maybe you won't have to tear into as much?

Here is the link...http://www.radiomanual.info/schemi/Surplus_NATO/Collins_51J-4_serv_user_1958.pdf

Hopefully someone with some experience here will chime in.

Best of Luck...
Ken

[WBear2GCR]

assuming you can get to the shaft, I'd put a few drops of Naptha/BBQ starting fluid onto the bushing of the switch.
if it goes through a panel bushing, remove that, clean with same or alcohol, then lube with either "30k" RC model "shock oil"
(used on model cars...) - a less viscous grade is ok too, or silicone grease is good too. These lubes do not gum up ever.

Assuming the naptha loosens up the goobered lube in the switch bushing, then you can supplant that with some
synthetic motor oil or if you can clean it out with spray contact cleaner, then a light grade of the silicone shock oil...

in some cases I've seen shafts and bushings that become "galled" - some of one part gets scrubbed off and forms
a nub that locks the shafts together. That's tricky, sometimes you have to remove the lock ring from the switch shaft
above the bushing and then slide the bushing assembly off the shaft or at least away from the problem area...

I'd avoid WD-40 myself.
If you use it, remove it with contact cleaner, and then relube.

A syringe with light synthetic oil can sometimes reach into a very difficult to reach switch bushing...

                            _-_-

[WBear2GCR]

I own an R-388/51j-2/3  it has a similar arrangement for the BFO adjust...

The shaft going through the variable cap inside the BFO can does gall up and become super stiff.

So does the ant peaking control (a similar cap).

I'd pull the shaft off the coupler, take the coupler off and try to clean then lube the shaft
where it meets the bushing... assuming you can get some light stuff in there, and only a drop or two
will suffice, that naptha, or a naptha reduced synthetic oil is VG in a syringe with a needle, and you can rock
the shaft to free roatation (it does go 360 degrees, if it is like mine), then hit it after a while (like a day)
with a few extra drops of synthetic motor oil - rotate to run the oil into the bushing... the naptha from the
original injection will evaporate, the synthetic motor oil will not...

failing that, you'll need to remove the can from the unit, and then probably remove the cap and do some
surgery of the type I mentioned earlier.

Seems that the BFO cap shaft is the smaller inner shaft, and the switch is the outer, which may complicate this...

I need to do just this with the #2 R-388 that is here.

I assume the mechanical filter switch rotates ok??

I'm sure a more than a few on here have worked on the 51J-4 BFO mechanicals...

                           _-_-bear

[w3jn]

Mix some acetone and ATF - maybe 50/50.  Lay the radio on its back so the switches are facing upwards (so the mixture can weep its way into the bushings better).  Using a syringe inject a bit of the ATF mixture into the shaft bushings of the switches, let it sit a day, and work the switches.  Repeat as necessary.  Final lube of the bushings should be a bit of thin oil, preferably synthetic.  I've also used teflon grease and that seems to last quite well.

I've not done this on a 51J but have on other radios with spalled/frozen switch shafts.

Rremoving the dial and/or the PTO is no real big deal.  In fact, if the PTO endpoint is off you may want to remove the PTO and adjust the endpoint anyway.  By now you'll have to pull the PTO cover and remove a turn off the endpoint adjust coil to get it into range.  There are internet articles on how to adjust the endpoint with the PTO out of the radio.

[WBear2GCR]

Yes, jn, that acetone and ATF is indeedy magic "foo-foo juice"!!