As an unintended side effect of my unbridled parts collecting, I have, against my will, acquired three relay boards. While I was cleaning them up to determine which one to use in my build, I noticed some significant differences.

The top board has deep channels whose sides have been melted over the wires to hold them in place and four places where the wires are elevated to provide a larger gap between neighboring wires.
The middle board has shallow channels and four places where the wires are elevated.
The bottom board has shallow channels and no elevated wires.

All three boards are marked with 9680 but only the top board is marked with 914.610.104.00.
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I'm assuming that the top board is the latest version and seems to be be of the highest quality.

Any insight into the progression between the years would be welcome.

Thanks.

George

@914sixer
Mark has seen a few and may have some insight.

i'd make a wild assumption it goes the other way.......as a cynic.
the quality goes down the newer it is.

but lets see what the experts say.

Wonder if the first pic is for a six? The fuel injection harness plug area looks different.

98% of the boards I do are the deep groove. I have only seen a few shallow boards. I am guessing that there was a progression from the bottom board to the top board is far as production went. If any water got to the no groove board it would be easy to short out the board. Also if the board took a power surge the lower and middle boards would make it easy to short across too.

@dion

No. 6 boards are differemt and have the tach transducer. Mark said the 6 board he did had all soldiered connections.

I'm wondering about the weird melt lines on the top board. Has anyone seen that on other 'deep' boards? It looks like someone took a hot soldering iron to the plastic and melted it - maybe to keep the copper runs imbedded? Wondering if factory or done after...

Yes, most of the late boards have the melt lines to keep strips in the slot. Done from factory.

Personally I appreciate the relayboard and what it does for our cars. I read somewhere that the 914's relay board was first of its kind in the industry at the time, an innovative approach and solution for the day.

It functions as a central connection node for a few of the important major systems in the car by componentizing them - main wiring harness for power control, lights & gauges, another harness for the fuel injection system, an integrated connection for the battery charging system harness, and finally another harness for the engine ignition system. Without it we would be left with a single massive harness connecting all these things which would be a nightmare for troubleshooting, and make maintenance much more challenging.

Wondering if the first board had been previously "rebuilt" Looks like a lot more manual work involved in getting it to its current state, soldered connections, board melted over the traces, etc.

Makes me curious to go look at the stack of boards I have.

Also, I have found bathing the boards in this stuff to be pretty good at eliminating gremlins caused by oxidation on the connectors and riveted joints

https://www.amazon.com/Hosa-D5S-6-DeoxIT-Co...r/dp/B00006LVEU

relay board for a 914/4 is part # 914 610 104 00

relay board for a 914/6 is part # 914 610 103 00


found this doing a google image search.
from pelican parts forum. posted by rick raes in 2011
a 914/6 relay board.

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2 things.

it does not have part # on it.
this is also noted by george kopf for the two shallow groove boards he posted.
it does have a number on it. 9681. not the same as 3 above with 9680.

where protective tar material is chipped away looks like its shallow groove plastic casting like two of the boards above.

i'm going with the deeper grooves as the later version.
to reinforce the relay board against warping/curling due to heat?

in some ways the earlier boards are more carefully made and the later board a little cruder, but i imagine the change was provoked by some early failures within a couple of years of being made as the change is occurring during the production run.

the boards are the same thickness/depth so its not about getting a thicker coat of tar?

only form of failure i can think of is heat distortion due to insufficient stiffening?

deeper grooves assist assembly and reinforce at the same time.

agree with jeff b. its a thing of wonder. and made to go outside in the weather.
no one else was really doing that with "printed" circuit boards. putting them out in the rain.