Reviving vintage Realistic DX-302.

[Baronski]

Hello, trying to get this new old radio up and running. Mostly just needs the old baked in 40 year old grease removed and replaced.
It's coming along nicely and I am moving cautiously to avoid mistakes.
Can anyone help correctly identify this control? I call it a precision tuning shaft, but can't seem to find any info searching the net.
I have successfully repaired this one, but accidentally had it disassemble.

 

[JimB]

Hello and welcome to ETO.

I am not familiar with the DX302, but that tuning drive looks like a variation of an epicyclic ball drive.
They use ball bearings instead of gears.
Various types have been available over the years, look here:

https://www.mainline-group.com/collections/reduction-drives-classic-6-1

To work correctly the grease inside them should be fresh and not all dried up.
Also be aware that as they wear, they can become quite "lumpy" in their rotation.

The drive in your picture looks to be particular to the DX301, rather than an off the shelf component.

JimB

 

[Baronski]

Yes, there is a small inner shaft, one end has the knurled host for the knob, the other a curved radius that makes contact with 4 bearings. 3 main bearings and one smaller bearing that sits in a divot on the other side, making contact with a spring in a guide. The inner shaft moves at a greater ratio than the main shaft. I assume they work by friction.

This one here was an easy fix. I simply removed the coupler and the whole assembly came out. But I couldn't figure out how to disassemble it. So I cleaned it up well assembled and packed in some WL grease. Worked good I guess.
When I went to put the face plate back on I didn't have the shaft correct and the pressure popped the inner pin out somehow. I corrected my mistake and properly cleaned and greased the parts. Reassembled and all is good.

However, I have two more of these to revive.
My question is how do I disassemble these correctly? I hate to just give a hard tug on the inner shaft.
Don't want to destroy something I cannot replace.
Thanks for the advice.

 

[Baronski]

"planetary reduction drives"

 

[shortbus=]

So I cleaned it up well assembled and packed in some WL grease.

If the grease you referenced as WL is "white lithium" grease, I'd recommend changing to something else, if you want these to work long term. White lithium grease dries out and cakes after a very short time if the parts don't move much. Even common petroleum grease, like the brand named Vasoline, is much better because it doesn't dry out or cake up.

 

[Baronski]

Good to know, thanks.
Do you know how they disassemble?

 

[rjenkinsgb]

Do you know how they disassemble

The ones I've seen are either pressed /crimped or have folded edges during manufacture and are not intended to be dismantled.

I'd be tempted to just use solvent degreaser to clean them, then re-lubricate without taking them apart.

 

[Nigel Goodwin]

The ones I've seen are either pressed /crimped or have folded edges during manufacture and are not intended to be dismantled.

I would agree, they aren't designed to be taken apart - and aren't really designed to be lubricated either, once they reach that stage they have long since passed their design life.

 

[Baronski]

These had grease from the factory. After 40 years in storage, the grease had lost all moisture and was either goo'ed up and would barely turn or was locked up completely. I have used both a degreaser/washer and contact spray to clean and loosen then up. Looks like I'll just pack some grease in and call it good.
Thanks for confirming the assembly.

 

[Nigel Goodwin]

These had grease from the factory.

Perhaps I explained that poorly - they weren't designed to be re-lubricated once they have been originally manufactured.

Actual tuning capacitors used to seize up as well, motors and turntable bearings in record players, lots and lots of age related lubrication failures.

 

[rjenkinsgb]

Looks like I'll just pack some grease in and call it good.

I'd be tempted to try an aerosol grease, as that has solvent added to make it flow - it should run in to the bearing, as long as there is some way to get it in there.

The solvent evaporates fairly quickly and leaves normal consistency grease behind.

 

[Baronski]

Not lubricating anything with ball bearings just seems wrong to me.
I appreciate your feedback and know this is true in some cases.
It reminds me of when we were kids doing maintenance on our bikes, we used WD-40 thinking we were making everything good. Only to find out quickly the damage we did to the bearings and races.

I am using aerosol to get to hard to reach spots.
Insane clock-like gear mechanisms. looks so primitive compared to today's electronics.
The MHz drive with the red mark is the one giving me the most trouble.
Maybe one more cleaning session.

 

[JimB]

It reminds me of when we were kids doing maintenance on our bikes, we used WD-40 thinking we were making everything good.

WD40 is one of those universal things which is not all that good at most of the applications for which it is used.

Lubricant - so so
Penetrating fluid - not so good
Water Displacing fluid - OK maybe ( I have never used it for this)
Cutting fluid - Great when machining aluminium (Drilling, turning, milling, tapping )

JimB

 

[Baronski]

Indeed. Yet I still have a can in the garage.
It cleans up rust on bolts pretty good.

 

[rjenkinsgb]

Water Displacing fluid

That's it's main feature - it is excellent for that, it was great on old car distributers when they got damp!

I used it as a treatment for any aluminium antenna I bought or built, to saturate the anodised surface.
The stuff thickens and just about sets over time, and some I took down years later still looked as good as new.

The thickening as the solvents evaporate is why it's so poor as a penetrating fluid, it does not stay "thin" for long.

 

[Baronski]

What is best for the potentiometers or variable resistors?
Contact cleaner?

 

[Nigel Goodwin]

WD40 is one of those universal things which is not all that good at most of the applications for which it is used.

Lubricant - so so
Penetrating fluid - not so good
Water Displacing fluid - OK maybe ( I have never used it for this)
Cutting fluid - Great when machining aluminium (Drilling, turning, milling, tapping )

JimB

Great for water displacement, it's original purpose - but also great as a switch and potentiometer cleaner, because of the lubricant it provides. It was my switch cleaner of choice for decades, and still is.

 

[Baronski]

I tried to stay away from certain Deoxit sprays because it appears to leave behind too much residue on the resistance tracks and wiper.
Is WD-40 OK because it contains no anti-oxidents? I would have never guessed WD-40.

 

[Nigel Goodwin]

I tried to stay away from certain Deoxit sprays because it appears to leave behind too much residue on the resistance tracks and wiper.
Is WD-40 OK because it contains no anti-oxidents? I would have never guessed WD-40.

It's fairly controversial

However, in 46 years as a TV/Radio service engineer it far out performed everything else we ever tried - although I was a few years in, before I tried it. Most sprays remove the pot's lubrication, often making it worse, WD-40 cleans and adds a little lubricant.

What you MUST NOT do is spray it inside a cassette player

 

[Baronski]

I have no tape media for years now. Although I see the old cassette format has returned.
Most popular bands now offer it as a media option for purchase.
Something I thought I would never see.