Dialog console pushbutton switches - are new switches available?

Mud · Mar 20, 2015

Anyone have a source for new Rafi switches for the Dialog operator console? Or an effective way of making them work properly? I've tried cleaning them with contact cleaner which works for some, but some seem to be beyond that. Testing the balky switches with an ohmmeter show high and varying resistance when the contacts are made, so I imagine the contacts are just dirty but I don't see a way to get the switch apart to clean them without destroying the plastic body.

What have you guys done about this? I don't remember seeing anything posted here. I found some used ones, but they are about the same as what I have. Makes operating the machine frustrating and not confidence inspiring to say the least. I'm contemplating looking for compatible replacement switches and buttons from a domestic source.

The real Leigh · Mar 20, 2015

Google says RAFI switches are made by C&K, a large well-established US switch manufacturer.
Industrial Controls - RAFI Switches By C&K Components

They are stocked by Mouser and Newark, two major electronic distributors.
Mouser Electronics - Electronic Components Distributor
Newark element14 | Electronic Components Distributor

- Leigh

Mud · Mar 21, 2015

I called Mouser and Newark and Digikey 3 months ago, they told me the switches I need are NLA. The surplus sellers on the web list them, but no one seems to have any. The surplus listings seem to be bait, like, if they get a request they'll try to find some, sort of thing.

Other ideas?

The real Leigh · Mar 21, 2015

Most of the so-called "surplus dealers" are just brokers. They have no stock.

They advertise everything but have nothing.

One exception is Surplus Sales of Nebraska, which has a very large stock of electronic parts.
Surplus Sales of Nebraska - Hard to Find Electronic Parts

- Leigh

rklopp · Mar 21, 2015

Are you sure the problem lies with the switches? My FP2NC acted like it had pushbutton problems, to the point I convinced myself that if I pushed off-center with my finger, they worked better. It got worse and worse, and eventually I could only use the remote pendant for cycle starting and stopping. It all turned out to be broken traces on the NBP 52 board under the pushbuttons in the control panel. I found and mended the offending traces, but the fix wouldn't stay fixed. I was able to buy a replacement board from Martin, and that fixed everything.

The real Leigh · Mar 21, 2015

rklopp said:
It all turned out to be broken traces on the NBP 52 board under the pushbuttons in the control panel.

Chicken and egg.

The push buttons became intermittent.
So you started pushing harder to make them work.

The excessive pressure broke the PC board traces. They don't break of their own accord.
Fixing them returned the board to its earlier unreliable condition with the intermittent switches.

- Leigh

Mud · Mar 21, 2015

I'm pretty sure it is. It's not all the switches, just the most used ones, and when I test a flakey one with an ohmmeter, the resistance rises and falls as I watch the meter. After cleaning with contact cleaner it's much lower and steady, but still not as low as on a pair of unused contacts in the same switch. I swapped the E stop switch with the rapid switch, because the E stop only used the NC contacts and the rapid only used the NO contacts. Before I did that, I tried cleaning the rapid switch contacts to no avail, the resistance stayed high and the actuation was erratic, after swapping them both switches are now using previously unused contacts and the rapid works perfectly. I did clean a couple that got better, so it does work sometimes. I'm using a plastic safe contact cleaner I got from McMaster.

Before I struggle with cleaning every balky switch just to see if they improve, I thought it would be a better investment to just install new switches. I purchased a few used switches from the west coast to try, they aren't great resistance wise so that doesn't seem to be a good solution.

The real Leigh · Mar 21, 2015

Mud said:
I purchased a few used switches from the west coast to try, they aren't great resistance wise so that doesn't seem to be a good solution.

Any new or serviceable switch should show contact resistance of less than 1 ohm.

Make sure you subtract the resistance of your meter test leads when reading low-resistance components.

- Leigh

rklopp · Mar 21, 2015

Uh, no, the pushbuttons stayed the same, and don't require hard pushes with the new board. Besides, how would you know - you've never touched my machine AFAIK.

The real Leigh said:
Chicken and egg.

The push buttons became intermittent.
So you started pushing harder to make them work.

The excessive pressure broke the PC board traces. They don't break of their own accord.
Fixing them returned the board to its earlier unreliable condition with the intermittent switches.

- Leigh

The real Leigh · Mar 21, 2015

rklopp said:
Uh, no, the pushbuttons stayed the same, and don't require hard pushes with the new board.
Besides, how would you know - you've never touched my machine AFAIK.

I play with your machine every night. You said it was OK. Perhaps you forgot. :crazy:

But seriously...

I've designed many products that used such switches, often using product from C&K since it's one of my preferred vendors.

And I've analyzed examples of those products that failed in the field.

The main issue I see here is the open PCB traces.
They don't open spontaneously. That's a result of stress way beyond their spec.

The fact that the opens only occur on buttons that are heavily used supports the excessive-force hypothesis.

- Leigh

Mud · Mar 21, 2015

The real Leigh said:
Any new or serviceable switch should show contact resistance of less than 1 ohm.

Make sure you subtract the resistance of your meter test leads when reading low-resistance components.

- Leigh

Is there anything else obvious that you think I've overlooked?

The real Leigh · Mar 21, 2015

Mud said:
Is there anything else obvious that you think I've overlooked?

I don't know.

When you make statements like...

Mud said:
I purchased a few used switches from the west coast to try, they aren't great resistance wise...

It's hard to tell whether or not you know what you're talking about.

That's hardly a "technically precise" description.

- Leigh

yzfr1pwr · Mar 21, 2015

Can't you just use another switch that you know to be good to test the circuit? Like one of the others on the console. Or you could get overly technical like some certain other jabronies suggest , pontificate and miss the problem completely. You know like not realizing O- rings don't seal so good when it's real cold but the telemetry "was" dead nuts.

Obviously not going to help find another good replacement but could confirm good or bad switch.

Mud · Mar 21, 2015

I did. Post 7 describes how I swapped 2 switches and the problem went away. Cleaning a few switches made it better if the resistance was real low and stable after the cleaning, not all the switches respond to the cleaning with reduced and stable resistance. And no, I don't remember the exact figures I got, it's been a few months since I did that. None of the used contacts after cleaning had resistance figures as low as the unused contacts did without being cleaned, so I'd like to install brand new switches in the most used locations if I can get them.

In an extreme case, an axis switch would intermittently pause and restart the axis when held down in mode 5. I started looking for a board problem, then moved to the switches. The varying resistance on that switch resembled the action of that axis, it seems the board will move the axis below a certain value, and stop above that value, it didn't need near 0 resistance at the switch to operate. I have it working, but I hate 'good enough'.

Scottl · Mar 21, 2015

Mud said:
I called Mouser and Newark and Digikey 3 months ago, they told me the switches I need are NLA. The surplus sellers on the web list them, but no one seems to have any. The surplus listings seem to be bait, like, if they get a request they'll try to find some, sort of thing.

Other ideas?

If you know the P/N of the switch perhaps C&K may be able to cross reference it to a newer P/N that would be compatible. It can be a real PITA to source a few pieces of an obsolete part but the manufacturer should be able to provide a spec sheet that can be used to compare possible candidates.

There are plastic safe contact cleaners but the problem is probably more than just dirt

Edit: Do you know the P/N for the switches?

Mud · Mar 21, 2015

Scottl said:
If you know the P/N of the switch perhaps C&K may be able to cross reference it to a newer P/N that would be compatible.

Edit: Do you know the P/N for the switches?

Good thought Scottl, I'll call them. I'm not used to that happening, but I have had occasional unexpected luck. These switches attach to the button that is fastened in the panel, I was envisioning replacing every button along with every switch, and I'd prefer that it remained original on top.

The number on the switch is 1.20.115 but I believe that's a generic prefix. Here's a photo.

yzfr1pwr · Mar 21, 2015

Mud said:
In an extreme case, an axis switch would intermittently pause and restart the axis when held down in mode 5. I started looking for a board problem, then moved to the switches. The varying resistance on that switch resembled the action of that axis, it seems the board will move the axis below a certain value, and stop above that value, it didn't need near 0 resistance at the switch to operate. I have it working, but I hate 'good enough'.

Normally I read all posts before I reply, not this time.Certain Ignorant comments inspired me to post hastily.

My X buttons have the same issue so I am interested in this subject. But they are not bad enough yet to force me to try to fix them.

I would go to Germany if the Oem does not pan out for a replacement. Franz or FPS probably has a good source for replacements.Then when you get one or more from them and confirm they work well you can reference that switch and try and find it domestically if you have other semi bad switches you want to replace.

It may be something that Master ,Mouser, etc. can get but don't have or are not in their system due to little to no demand.

If that is the case they may want a minimum order that may be more than you want but if the price difference is great enough from franz or FPS than I would think possibly there are others here who would pitch in for an order by having each guy call his own order in to Master etc. to fill the minimum qty.

The real Leigh · Mar 21, 2015

yzfr1pwr said:
It may be something that Master ,Mouser, etc. can get but don't have or are not in their system due to little to no demand.

Mouser's online catalog lists every product they can get.

It's quite common to find items annotated "non-stock item" with a price and minimum order quantity.

I can't comment on "Master" since I don't know who they are.

- Leigh

ballen · Mar 22, 2015

Gentlemen, are these the same switches that are available new on German Ebay from Singer, item 380838928925? The price (90 Euro for 8 switches) seems a bit high but if the quality is good, perhaps that is worth it.

Drucktaster Satz 8 Stück für konv. Deckel Fräsmaschine | eBay

Other switches are available here and here.

(PS: my only connection to the seller is that I had done business with Singer many times and always been positively impressed and happy.)

Mud · Mar 22, 2015

Thanks, but they look like just the pushbutton that fits into the panel and I have plenty of them. Perhaps they have the switches too.

Dialog console pushbutton switches - are new switches available?

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