Ohmite Rheostat replacement?

[ra.ra]

Am greatly enjoying your post here, Mr. Head, and just to re-iterate: xmas111, JKent and RoyC are among your very best advisors here. Take your time, read/learn as much as you can, and then make your own decisions regarding restoration procedures. Just gotta say, sounds like Mrs. Stupidhead is rapidly inching toward the regal queendom of penultimate WAF.

[stupidhead]

Hi ra.ra,

The 15 ohm pots in your photo (I may have have been mistaken about the 16 ohm value) were excellent AR replacement potentiometers, which were sold into the mid 90's by the "authorized" AR parts source, AB Tech. They are usually stamped with the resistance value on one side, and many (not all) are stamped "Japan" on the other side. As I mentioned in my AK post, although they are virtually identical in appearance to the common (Chinese) 8 ohm L-pads available today, they are no longer available....and have not been for quite some time.

It should be noted that AB Tech (and others) have not changed the description of the generic 8 ohm replacement L-pads they sell at rather high prices today as AR replacements. In fact, in some cases the "8 ohm" stamp is being removed to deceive folks into paying more for them as "AR replacement controls". ABT still uses the term "potentiometer" on their website. These are readily available from a number of speaker parts dealers for much less.

As I've mentioned before, all variable controls (Ohmite, Russian, to the Chinese 8 ohm L-pads described above) will require servicing at some point. Those of you boxing in your open-back replacement controls should build in easy access for the future.

Roy

Hi folks,

I have no pics to share because a close inspection of the mongrel revealed no value numbers stamped in the side of it. The only identifying characteristics are shown already in previous pics. I will add those pics (already on the AK thread) just to consolidate the info here. I don't know who has worked on this speaker in the past, but it looks like the chewed the insulation off the wires! Again, no pics of the sides taken because there was no identifying marks, stamps or other signs. I have soaked and polished up my original and do have one question, I have seen a few references to spraying it down with dielectric grease which I can understand, but on the replacements commented on in this thread they are referred to as open backed, and should be somehow covered. While the original is not open backed, it is open sided and I wonder if it should also have some measure of protection?

[JKent]

close inspection of the mongrel revealed no value numbers stamped in the side of it.

No "mongrel" there--it's a fairly rare original AR replacement pot.

I have seen a few references to spraying it down with dielectric grease

Any dielectric I have used comes in a tube and is smeared on the metal parts.

While the original is not open backed, it is open sided and I wonder if it should also have some measure of protection?

Nope.

But DO be sure to install some sheer cloth behind the woofer to keep the fiberglass out of it. Originally there was "Kempac" in there, which is a kind of porous paper towel, but it's probably missing or deteriorated.

Kent