Tech: Rockola Selection Switch Cleaning

I just signed up for this group, and find there is a vast wealth of knowledge here. I am new to jukes, but not exactly new to tech forums. I have been a member of the Usenet group rec.games.pinball (RGP) for years (handle is Gott Lieb? there), and try to contribute where I can.

I have been looking for the best way to clean the selection switches on a Rockola juke. This is a 441 FWIW. Unfortunately, there is conflicting info out there. Some suggest tuner / contact cleaner, while others recommend Deoxit. I've even read someone suggesting tape head cleaner (not certain if they are referring to the liquid or not). Coming from an electromechanical background (pinball machine and EM arcade repair), using contact cleaner is a big no no. 24v or 50v switches in EM machines should burnished. I've worked on a couple of EMs where the owner sprayed contact cleaner at one time, and wish they didn't, (a lot of excess switch burnishing ensued).

I was able to clean the reset slide switch with a pencil eraser which worked very well. I would love to use the same approach for the selection switches, but can't see that happening due to the way the switches are mounted / configured.

What is the recommended procedure to clean the selection slide switches on a Rockola, where cleaning is possible w/o fouling the switches in the long term?

TIA,

Jim

Hi Jim,
Welcome !
If you are speaking of the sliding switches in the "keyboard", the "best way", for me, is to remove it from the phono, remove any "solenoids", and wash it using Ammonia (sudsy preferred), and HOT water. Rinse all Ammonia off, and totally dry, prior to using. After doing this, I check the switches using an analog meter--looking for (ideal) "zero" resistance through the "bank". If I can not achieve "zero" resistance, I sometimes use a"Q-tip" to apply DeoxIT5, to the "offending" switch. I will never "spray" it with anything. As a LAST resort, I will carefully dis-assemble, and "reform" the contact blades. Other people swear that they have great success dis-assembling and using a "Dremmile tool" (SP?) on the sliding blades. I don't like that as it, IMHO, has to remove the silver plating.
I agree 150% about using sprays on bladed contacts--even DeoxIt5, which I LOVE on sliding type contacts. I too, have had to do excessive "burnishing" on these contacts--
Ron Rich

Thanks for the tip, Ron! I never even gave ammonia a thought, but why not? It's the typical ingredient in most chrome / brass / multi-metal polishes. My only concern may be that the "wash" could wick in between the wire and insulation, causing potential corrosion down the road. Thoughts?

And yes, I was referring to the slide switches in the keyboard, so we are both on the same page. Not a fan of the Dremel for cleaning switches, although I know some guys in the EM pinball world who swear by it too.

Is there a reason why you prefer an analog ohmmeter over a DMM? I have an old, analog Micronta that i dig out on very rare occasions.

Jim

Hi Jim,
I have used the Ammonia for years--never had any noticeable problems--tho, I do rinse it well, in hot water-- ??
On the meters--most "Digitals" will not give true readings here. I have found that they will indicate switch closure, but not the ability to carry current. A good analog will show a resistance that my good digitals (Fluke--HP)won't show---
Ron

"Used for years with no issues", I'll buy that. Thanks again. I'll let you know how it goes.

Jim

40+---
Ron Rich

Just a follow up. I finally had the opportunity to take out the selection "keyboard". While the ammonia and hot water "bath" did an excellent job of removing the cigarette tar off the unit, the switches did not completely get clean.

I tested continuity on the circuits which are common when the slide switches are at rest. The circuits pass through the switch blades of each number or letter to complete the circuit from 1 - 0 and A - K. As I moved further away from the 1 or A terminal where the circuit originated, the resistance increased by 10s of ohms and finally 100s of ohms. At this point, I opted to take the slide switches apart to inspect.

I tried cleaning the contacts with rubbing alcohol and a Q-Tip at first. Nada. Then, I tried a pencil eraser. An eraser was not touching the oxidation on the contacts either. I finally settled on a fiberglass pencil. It did a great job! However, after cleaning the contacts, I found the equivalent of what you would see after metal has been soot stained from a fire (spotty black tarnish). Between seeing that and remnants of red residue, it appears that someone sprayed contact cleaner on these contacts at some point.

Got the keyboards back together, check continuity, and I was getting much more acceptable readings. Mounted the keyboard back in the box, troubleshot the reason why the write-in motor was still not running, and all is well now.

Thanks for the advice. I will not discount trying ammonia on the next one, should it need to be done. I hope I don't have to rip too many of these keyboards apart. It's a bit of a PITA to get it back together.

Jim

Hi Jim,
Glad you got-it--
Probably should have said that one must do the "Ammonia thing" a couple of times, and "work it into the slides"--also let it soak in--the "dirtier" the switches are, the more you need to do it--I have done it up to 5 times, if some "gepetto" (OK-"person") has sprayed something on them. Heat also helps get the Ammonia where it needs to go--
I have one slight dis-agreement with what you wrote--
It's not a PITA--it's a ROYAL PITA, even worse, is when some "person" has done it incorrectly prior to you "getting there" !!
Ron Rich

Yeah, I did bathe the unit several times in the ammonia solution. I even tried hitting it with a toothbrush. I just think this one was too fouled to put a dent in it.

Getting the second one back together was not nearly as bad as the first. When the first one was not going back together too well, I decided to strap the bottom of all of the slide switches with blue painter's tape. I taped them just below the notches in the slides, so the tape would not interfere with the slide action. It worked out pretty well. Still, I would not want to be doing this level of repair with every juke.

Jim