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> Solid State Relay Board
Steve_R
post Jul 6 2015, 05:28 PM
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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.




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JeffBowlsby
post Jul 6 2015, 05:35 PM
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Wow...
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steuspeed
post Jul 6 2015, 05:44 PM
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SirAndy
post Jul 6 2015, 05:47 PM
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Very nice!

Just a FYI, i was able to buy a brand new relay board from Porsche not too long ago.
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jim_hoyland
post Jul 6 2015, 05:59 PM
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Thanks for posting; I saw your car at the PCA Concours in Dan Point and was impressed with your relay board.....very clean looking. Is this going to be a one-off or are your going to produce them ? Even a kit would be very cool (IMG:style_emoticons/default/smile.gif)
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McMark
post Jul 6 2015, 06:00 PM
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Really cool! (IMG:style_emoticons/default/thumb3d.gif)

What's the back look like? Did you make the pins as well? I'm working on a similar project, but will be severely modifying the layout to better suit my car.
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Harpo
post Jul 6 2015, 06:04 PM
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Very impressive. You have some skills there.

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Mike Bellis
post Jul 6 2015, 06:09 PM
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I like it!

I'm running solid state relays on my car too. They work great and trigger as low as 3VDC.
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Mblizzard
post Jul 6 2015, 07:08 PM
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Holy crap that is cool!

Wish I had the cash as that is likely one of the best changes you could make in a 40 year electrical system.
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somd914
post Jul 6 2015, 07:12 PM
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Very nice work. Not in my budget right now, but perhaps in the future...
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saigon71
post Jul 6 2015, 08:15 PM
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Very impressive - nice work! (IMG:style_emoticons/default/beerchug.gif)
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Steve_R
post Jul 7 2015, 06:55 AM
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QUOTE(McMark @ Jul 6 2015, 05:00 PM) *

Really cool! (IMG:style_emoticons/default/thumb3d.gif)

What's the back look like? Did you make the pins as well? I'm working on a similar project, but will be severely modifying the layout to better suit my car.


Thanks,
The back is filled with epoxy to seal in all of the wires. I found a supplier for the pins. Are you using solid state relays?
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914Sixer
post Jul 7 2015, 08:47 AM
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Am I missing it or is there no plug for the heated back window? Very upscale replacement.
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Mueller
post Jul 7 2015, 09:40 AM
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Damn...that is a nice assembly....Tormach mill?
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thieuster
post Jul 7 2015, 09:47 AM
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I take my hat off, sir! Amazing stuff!

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clapeza
post Jul 7 2015, 12:07 PM
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Doesn't this belong in the Sandbox?

...because that is pure 914 porn!

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Steve_R
post Jul 7 2015, 07:47 PM
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QUOTE(914Sixer @ Jul 7 2015, 07:47 AM) *

Am I missing it or is there no plug for the heated back window? Very upscale replacement.


There was only room on the board for 3 solid state relays - Power, Fuel Pump and Heater.
Also, my car doesn't have a heated back window.
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McMark
post Jul 7 2015, 10:26 PM
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QUOTE(Steve_R @ Jul 7 2015, 05:55 AM) *

QUOTE(McMark @ Jul 6 2015, 05:00 PM) *

Really cool! (IMG:style_emoticons/default/thumb3d.gif)

What's the back look like? Did you make the pins as well? I'm working on a similar project, but will be severely modifying the layout to better suit my car.


Thanks,
The back is filled with epoxy to seal in all of the wires. I found a supplier for the pins. Are you using solid state relays?

Wasn't planning on it. I'm a bit of a nut about emulating originality, so I'm debating between original round relays and more modern Bosch square relays. But I still totally appreciate the upgrade to solid state. If I could find a solid state that looked exactly like an original round relay, I'll buy 100 right now. (IMG:style_emoticons/default/wink.gif)
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Mueller
post Jul 7 2015, 10:51 PM
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QUOTE(McMark @ Jul 7 2015, 09:26 PM) *

QUOTE(Steve_R @ Jul 7 2015, 05:55 AM) *

QUOTE(McMark @ Jul 6 2015, 05:00 PM) *

Really cool! (IMG:style_emoticons/default/thumb3d.gif)

What's the back look like? Did you make the pins as well? I'm working on a similar project, but will be severely modifying the layout to better suit my car.


Thanks,
The back is filled with epoxy to seal in all of the wires. I found a supplier for the pins. Are you using solid state relays?

Wasn't planning on it. I'm a bit of a nut about emulating originality, so I'm debating between original round relays and more modern Bosch square relays. But I still totally appreciate the upgrade to solid state. If I could find a solid state that looked exactly like an original round relay, I'll buy 100 right now. (IMG:style_emoticons/default/wink.gif)


What is the diameter of the stock round units? There are mini-ISO relays that are ≈25mm square, maybe remove round covers and put these over? There are smaller ones but then you get into thru hole mount or surface mount assembly and your costs are really going to go up.
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Maltese Falcon
post Jul 8 2015, 12:20 AM
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+1
First Class product
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