Rehab for Analog Controls (pots, gear lube, and paint)

[Major Rock Hardy]

OK, you analog controls fans - here is a post for you...

so I've got some analog pedals and a SW yoke that all take 5 Kohm pots.

Even if I wanted to order from Happ, they want $10.45 for their cheapest replacement pot:
http://happcontrols.com/joysticks/50206400.htm

Question 1: Does anyone know what the difference is between the 2 different 5 kOhm pots (Other than the part number and about 20 bucks)?

Now I know (at least I would hope) these are not your typical off-the-RadioShack-shelf pots, they are heavy duty, to stand up to arcade abuse.

Question 2: Does anyone know the longevity of the Happ pots (in terms of a cycle count?)


Now, doing a bit of google-ing this morning, I discovered these that have a 2 million cycle life:
http://www.bitechnologies.com/pdfs/p232.pdf

at Newark, they are available for about $6 each, with price breakdowns as you go up in quantity... which seems like a pretty good deal, but I'm not sure... then again, there's also the following that have a 500,000 cycle life and are about $3:
http://www.bitechnologies.com/pdfs/p230.pdf

... perhaps I can get away with those.
edit: the above BI technologies pots available from Newark both have shafts longer than the Clarostat pot I pulled out of the yoke, so they may have to be cut down.

Questions 3 and 4: Has anyone rebuilt analog controls using these or even cheaper pots and if so - how did it go?
Does anyone know what the difference is between Sealed and Dust-Proof?



Next topic, gear lube for the plastic (nylon?) gears in the pedals/yoke.  I just figured some automotive grease would be fine.

Question 5: Anyone not recommend this?


Final topic, paint.  I was going to use some sandable primer I bought at Autozone, followed by black paint.
Questions 6 and 7:
Anyone remember the sheen on the original SW yoke (Flat or Semi-Flat or Gloss)?
Do I need a clearcoat on top of that?


I am hoping to turn this into a wiki page for others who would rebuild analog controls - any links you can send would help.

Cheers,
MRH

[u_rebelscum]

Q 1: Linear vs logarithmic vs S-taper.
Linear: signal output aka resistance "Y" depends on angle turned "X" (Y=a*X).  If graphed, it looks like a straight line.
Logarithmic: the resistance varies differently between different angles.  If graphed, it looks like a log or reverse log.
S-taper: a log and reverselog pot in one one, joined in the middle.  If graphed, looks like an "S" or reverse "S" depending on which the happs are. (See attached)

Q 5: Make sure whatever you use is plastic save.  Some lubes eat plastic, others are fine.  I like white lithium grease (for trackballs), but others here recommend other just as good stuff. 

[Major Rock Hardy]

Robin, I figured it would be you to respond...

so that would explain the difference between the Happs and the ones I found - since I found Linear pots.  Do you know if pedals and a yoke should be a s-taper for sure?

Thanks,
MRH

[u_rebelscum]

Do you know if pedals and a yoke should be a s-taper for sure?

First, I don't have happ's S-taper POTs, so I don't know which "S" curve it outputs.  I think it's the "reverse S" where the middle is less sensitive than the edges.  Either way though, you need to make sure the POT is centered at the center of movement; otherwise it will favor one side or the other.

Pedals definitely should be linear.  Since they don't have a center like a joystick or yoke, you'd get a "dead zone" in the middle if it's the way I'm guessing, or a very sensitive middle if it's the other "S".

And I'd go linear for the yoke, too.  Especially for the Y axis.  The X axis is more a matter of opinion, and what the original POT was.  I have driven cars with loose steering, and one with uneven steering: yuck IMO.

Joysticks, OTOH, I might go S-curve.  If it wasn't so expensive and I had an arcade analog joystick.

[Major Rock Hardy]

Yeah, I am pretty sure I am going with linear.  I was google-ing around the RGVAC newsgroup last night and I found this great thread about this subject so I will post the link:

http://groups.google.com/group/rec.games.video.arcade.collecting/browse_thread/thread/b5145ddd10db0d3c/e657b162e51273de?lnk=gst&q=star+wars+clarostat&rnum=1

... the OP asks about finding a replacement Allen Bradley (AB) brand pot, part # EJA1N048F502M Type EJ.  This is the exact same part # that was on the Clarostat pot I pulled out of the SW yoke.  Apparently Clarostat bought AB at some point.  Getting to the point, the OP mentioned that his investigations revealed that this pot is Linear (i.e. not S-taper).  This is my best feeling that the yoke should be a linear taper pot.  I agree with u_rebelscum about the gas pedals being linear as well.

and here's a quote from Clay Cowgill regarding longevities:

I'll be the killjoy of the group and put out a caution for using a
RadioShack pot (or anything else under $5)... If you're actually going to
run the game in an arcade or on location you may well be wise to spend the
extra $20-30 and get a good quality one instead.

A lot of the cheap pots have a rotational life of ~10-50K cycles as a MTBF.
If you figure an average game might have 50-200 "turns" on the pot you can
see that you might actually wear out the cheap part in a few hundred games.
Obviously for home use that's a LOT of time, buy if you have it on location
and it gets played 10-50 times a day you might well be replacing it again in
a few months.  For arcade use, a pot with 1M+ revolution rotational life can
save some headaches at the expense of ~5x the cost (usually easily recovered
on one service if you have to pay for technician time to perform the
install)...

(I haven't looked into how tough it is to replace the pots in Paperboy, but
if it's like other Atari games it's worth the $30 to just do it once in my
book. ;-)

...although I don't own an arcade, the yoke games are very popular at the house on the MAME machine, so the above is testimony enough to get the good stuff - although I'm still not going with HAPP.

I also came across a thread on RGVAC recommending Jameco part# 13995 for all Atari and Williams potentiometer replacements.  It's still a bit more pricey than the one I found above though, and no longevity information.