Solid State Relay Board Options

[Steve_R]

Well, it’s been about a year since I finished my 914 restoration, you can read all about it

HERE.

Everything works perfect except for the electrical problems I’ve been having with the relay board. I spent lots of hours trouble shooting electrical issues with the fuel pump. It turs out that my relay board had some bad connections for the fuel pump relay. After searching this site I discovered that the relay board is truly the weakest link in the 914. I tried to remove the epoxy bedding underneath the board and resolder the connections. This worked for a while but the fuel pump would sometimes stop and kill the engine. I finally figured out that the contacts for the fuel pump relay to the board were causing the problem. This seems like a never ending problem. I could buy another 40 year old used board and have the same problems.
So, to make a long story short, I decided to design a new relay board from scratch. I replaced the original electromechanical relays with industrial solid state relays. They have the same connection labels as the stock relays: 85 & 86 for the coil and 30 & 87 for the switch. The relays are available at most electrical parts dealers like Mouser or Digi-Key if one ever needs to be replace. They also use a lot less power than the original 914 relays. Also, since they are solid state and don’t have any moving parts they will last a lot longer and are more reliable. I also replaced the old ceramic fuse with a modern ATC style fuse and added an LED that illuminates when the fuel pump has power. This is great for trouble shooting fuel pump issues. It comes on for a few seconds after the key is turned on and stays on when the engine is running. Also, I removed the connections and plug for the rear window defroster. I used wires soldered to the connectors eliminating all of the riveted connections. All connections are soldered. To make the board I CNC machined the board out of high density polyethylene plastic.
I built a few extra boards to offset some of the development costs. They are quite labor extensive to build so I don’t plan to mass produce them. PM me if you want one. I would like to get $500.00 each. That includes the board with the solid stare relays. It does not include the voltage regulator. I used a solid state one from Pelican Parts. Both the stock and solid state voltage regulators will work.

[N_Jay]

So close, but so far.

I certainly understand why it is a $500 part, but it is hard to justify at that price.

Maybe someone else here could pick up the project.

We are all (most all) tinkers, so all we probably need is a kit with the board cut/molded and the hard to source parts. (Probably just the pins, since automotive relays use regular 1/4 blade connectors.
As an EE I offer my (limited) skills, as this is mostly a machining/manufacturing project.

Anyone? Anyone? Beuller?

[Whitney Mic]

So close, but so far.

I certainly understand why it is a $500 part, but it is hard to justify at that price.

Maybe someone else here could pick up the project.

We are all (most all) tinkers, so all we probably need is a kit with the board cut/molded and the hard to source parts. (Probably just the pins, since automotive relays use regular 1/4 blade connectors.
As an EE I offer my (limited) skills, as this is mostly a machining/manufacturing project.

Anyone? Anyone? Beuller?

Well... It's not C-n-C exactly, but:

I have a 3-D printer, but from the pics of the block the design is far too complex for *my* skills. If the C-n-C uses a file I could export, convert and run on my printer, I can try to build the base plate.

If that doesn't work out and someone has the chops to CAD both sides of the relay board and send me an .STL file (or similar), I can convert that and put it on the printer and see what comes out. I've seen some very nice technical drawing since finding my way into the World, there must be someone around with the design skills I lack.

The 3-D printer I own can build to a volume of 6" X 9" X 8". I don't knowhow much time it would take to build this piece. So far I have printed some good, strong parts using ABS and PETG plastic; the PETG prints, but my machine doesn't really get hot enough for the stuff (if I could get it a few degrees hotter, PETG can print pretty much clear pieces).

Here's a piece I'm working on for the center console gauges so they point at me instead of at the interior light:


(sorry, it's a yuge pic) The piece is just a prototype, I will print them in black, sand, finish, and paint the ones I use in my cabin (I might even see about building them 10% larger and having a set cast in aluminum and anodized).

I can print in other plastic types as well, but will have to order material, set up the machine and see how it goes.

I am trying to learn how to design this stuff a bit late in life and the learning curve seems sharper for some reason. I might be able to build something close-ish, but doubt I could do the job right with my current skills.

I'm willing to donate the materials and time on the machine for prototyping a board if someone wants to give it a go. Once I have an idea of cost of material and time, I could figure a fair price for this part of the puzzle...No way I could handle a huge demand though. I'm still trying to figure how to get the printer to pay for itself and justify the price.

Putting it out there, just in case.

-- Whit