Boost gauge help

[Brian 503]

Here is the main circuit board to my boost gauge which controls my ladder shift lights. The previous owner ripped the knobs right off the board. The knobs turn clockwise and counter clock wise to raise or lower shift light indicator by 100 rpm. Their is also a spst tac switch if u press in the knob which controls the shift lights to be on/off or if held for 3 sec resets programmed settings back to stock. This part I'm not concerned with. I'm concerned about finding out what part I can get to replace the rotation factor of the knob. I'm wondering if I can use a volume Potentiometer to dial in the shift light settings.  I'm assuming these three knobs are a Potentiometer? I wish it was as easy just to order replacement parts but it's basically impossible. Only 1000 of these were produced. Any insight or help is appriciated!

[Modded Matt]

They appear to be a simple Pot...

[Brian 503]

The actual knob has 3 metal fingers that spin across the metal plate. I'll test my luck at it  but I need to do some voltage test to see what type of voltage is being fed to the pots.

[RDC]

There's something odd about the way the carbon trace is laid out inside there, almost like they are something between a POT and an Encoder, and I'd say they are almost for sure some kind of Encoder because of the way the Resistors, R1 thru R6 are setup on them.

A typical linear POT will not work right in place of those.

The voltage isn't going to be anymore than 14.4v for it, and is most likely just 3.3v to 12v, with 5v being best guess.

This isn't what I'd say for sure they are, but it's more in the same layout versus how a POT would be used in there.  http://industrial.panasonic.com/cdbs/www-data/pdf/ATC0000/ATC0000CE15.pdf

I'd pull one from the board and get to measuring on it, then you'll know how it's laid out internally and can go about figuring up the correct way to replicate it or what to replace it with.

[Brian 503]

This is the whole knob assembly. U can see the 3 metal fingers on the bottom of the knob that go over the trace on the encoder. The 3 finger knob base rest on the metal ring of the encoder, them the metal cage snap fits over the knob base. The actual knob as a snap lock that locks into the base of the knob with the three metal fingers. That's the whole assembly. There's also that center plastic inside witch has a tac switch in the inside of it. The knob can be pressed down activating the tac switch as well. Though if need be would be pretty easy to bypass to any other spst tac switch.

[RDC]

It's for sure an Encoder, mechanical, and it looks like it's an 8 PPR (Pulses per Revolution) setup.

Check the dimensions of it and the leads against this one in the datasheet - http://www.digikey.com/product-detail/en/panasonic-electronic-components/EVE-YPCAJ008B/P17059-ND/5131186 and if it matches I'd give it a try.

[Brian 503]

Sweet thanks so much. Looks promising. Do the knob caps come with these encoders?

[RDC]

Nope, the knobs are not included, as there are as many types of those as there are different encoders.

[Brian 503]

Noon question, how would I find what knobs will fit that brand?

[RDC]

I'd make sure that one will work first, then deal with making it 'pretty' looking.

That particular one, the EVE-Y series, has a serrated shaft that is 8mm in diameter. It's not the D type shaft that is 6mm and what is shown in the pic there, and why you should always check the datasheet against the part number as the pic is sometimes just a general representation of the part.

The EVE-V series have the D type shaft, but DigiKey does not have them in the 8PPR, only in the 16PPR. They may still work, but they would be twice as fast when turning them if they did, and that's also why they may not work, as there are twice as many PPR for the chip there to be able to read.