Replacement Relay Socket Panel, Updated: Version 3 - Solid State Relays and Fuse Panel Replacement Options

[JoeD]

Yes please!

[914_teener]

I.m in after doing my latest "gremlin" project on my car.

[Evan0]

Thought of something...

While I love the wire color printed on the board, I thought some of the wire colors changed on different years. It may be better to simply label each connection with the original relay pin number (30, 85, 86, 87, 87a). If I were troubleshooting a car with that board installed and I wouldn't want to have to pull out and analyze the wiring diagram to translate wire colors to pin number and function.

On the fuse board, it would be prudent to add either a couple extra constant power connections and a couple switched power connections, OR add a couple extra fuses for add-ons.

It's not a big deal to add the relay pin number to the labels. But can someone confirm if the relay specific wiring connections changed color from year to year and if the relay wiring is significantly changed year to year?

Not a bad idea to add switched and straight battery power to the fuse panel, I'll add that to revision B.

Do you guys have opinions on how the fuses should be labeled? Should it indicate the amperage and a function symbol? What would be best to accommodate cars from different years?

[euro911]

(IMG:style_emoticons/default/agree.gif) ... All of the above mentioned items:

Fuse position # ... 1 ~
Fuse rating for each position
Function symbol for each fuse position would be nice too
A couple extra fuse slots labeled 'AUX'

[JeffBowlsby]

Yes different MY 914s have different fusepanel and relay circuitry. Fuse amperages and layouts changes too.

KISS. Just number the fuses 1-12 just like the factory schematics. someone else can figure out what goes where for the different years.

[Evan0]

Another question, how critical is the angle on the fuse panel in relation to the harness bundle? Would removing the tilt negatively affect strain relief on the harness? Optimizing the design for injection molding with that angle is proving to be a pain and removing that tilt would solve many issues. Thanks.

[Spoke]

Beautiful design. Looks really well thought out. Lots of good feedback from the guys too.

One question on the placement of SSR U6 for the low beam: Why is it turned around WRT to the other SSRs? With it's positioning, its exposed pad is not against the heatsink. Was this done for isolation? What is the theta-JC from junction to the EP versus junction to top of case?

[JeffBowlsby]

I amm pretty sure - not positive - that the slant is to enable a better viewing angle of the fuses where it is mounted. As long as the terminals are oriented normal to the back of fuse panel there is no unusual strain condition at each terminal

Wondering...what is intended for a fuse panel cover? The stock cover indicates the functions of each fuse.

[914work]

Wow cant believe I missed this thread.
Extremely nice work and commend your willingness to accept & incorporate the feedback !!!
Put me on the list~

[76-914]

(IMG:style_emoticons/default/agree.gif) Impressive! (IMG:style_emoticons/default/beerchug.gif)

[VaccaRabite]

Want want want want want.

Seriously. I want this.

Zach

[Evan0]

One question on the placement of SSR U6 for the low beam: Why is it turned around WRT to the other SSRs? With it's positioning, its exposed pad is not against the heatsink. Was this done for isolation? What is the theta-JC from junction to the EP versus junction to top of case?

I'm regretting the placement of U6 and it going to get flipped around for the next revision. I'll need to move a couple other components around to make that happen. I had it in that orientation originally to simplify routing. 7mm thick traces on both side are required to meet my current and temperature requirements, so routing was a bit of an issue. Thermal resistance junction to case is 0.3°C/W and junction to ambient is 33°C/W. The heatsink is approximately 28°C/W. I'm going to run a thermal test with a thermal camera with three of the relays carrying 12A, which should reflect worse case real world use. I'll incorporate anything learned from that test in the next revision.

Wondering...what is intended for a fuse panel cover? The stock cover indicates the functions of each fuse.

Thanks for answering my question. If its not critical to the connecting terminals, I think i will straighten it out to make injection molding much easier and cheaper. Is there a source for the stock cover? If reproductions are available, I would like to go with those to maintain some look of originality.

[JWest]

"3. The new fuseblocks do not have the bussed together lugs that the factory fuseblocks do, so makeshift additional terminal busses are needed or the circuitry is altered to accommodate, making the factory wiring schematic useless for troubleshooting."

This statement is not true. Engman had a flaw in his process of doing it, from what I understand, but did have it. Maybe he sold some without it? Mine have always been bussed just like factory and it is the most difficult part of manufacturing these, since they have to be fully disassembled and modified internally.

But irrelevant if this makes it into production. I am all for a better design, as I am not willing to put in the time to design a fuse box from scratch and the connection positioning is not optimal for the stock harness to bend around to reach. I keep it going since there is nothing better on the market.

Let me know when this makes it to retail sale and I'll push customers to it (or resell on my site if that is of interest to you).

[914_teener]

One question on the placement of SSR U6 for the low beam: Why is it turned around WRT to the other SSRs? With it's positioning, its exposed pad is not against the heatsink. Was this done for isolation? What is the theta-JC from junction to the EP versus junction to top of case?

I'm regretting the placement of U6 and it going to get flipped around for the next revision. I'll need to move a couple other components around to make that happen. I had it in that orientation originally to simplify routing. 7mm thick traces on both side are required to meet my current and temperature requirements, so routing was a bit of an issue. Thermal resistance junction to case is 0.3°C/W and junction to ambient is 33°C/W. The heatsink is approximately 28°C/W. I'm going to run a thermal test with a thermal camera with three of the relays carrying 12A, which should reflect worse case real world use. I'll incorporate anything learned from that test in the next revision.

Wondering...what is intended for a fuse panel cover? The stock cover indicates the functions of each fuse.

Thanks for answering my question. If its not critical to the connecting terminals, I think i will straighten it out to make injection molding much easier and cheaper. Is there a source for the stock cover? If reproductions are available, I would like to go with those to maintain some look of originality.

Personally I think the stock cover is not practical. Why not a sticker or silk screen over a cover One has to pull the fuse anyway to check it. .I.m with Jeff...KISS.

[Spoke]

I'm regretting the placement of U6 and it going to get flipped around for the next revision.

Very few products make it to production with Rev 1. I recently did a PCB for the people mover trains at Newark Airport where I reversed the coil leads for 6 relays. (IMG:style_emoticons/default/dry.gif). Fixed it in Rev 2.

[Evan0]

Update 8/26/2017

Been on vacation for the last couple weeks so not much progress. I did get around to doing a thermal test of the relay board.

Here's a picture of the test setup.

(IMG:http://www.914world.com/bbs2/uploads_offsite/i.imgur.com-20837-1503780005.1.jpg)

A 12V 600W power supply provides the juice to drive current through the solid state relays. Three 1Ω 200W resistors provide the load for the test. The fog, air fan, and low beam relays were chosen to as the test subjects since they are the high current draw items. The resistors actually measured about 1.2Ω so with 12V it should provide 10A through each of the relays. Left it running for about 20 minutes to reach steady state.

(IMG:http://www.914world.com/bbs2/uploads_offsite/i.imgur.com-20837-1503780005.2.jpg)

The max measured temperature was about 91°F, 15°F above ambient. Looks like the heatsink is doing its job correctly. The load resistors did get quite toasty during the test run.

(IMG:http://www.914world.com/bbs2/uploads_offsite/i.imgur.com-20837-1503780005.3.jpg)

With 30A passing through the PCB and the relays, there doesn't seem to by any issues. With these results I'll get to work with Rev B and figuring out how to mass produce these at a reasonable cost.

[davehg]

Any updates on this? I'm a few months away from tackling the electrical portions of my restoration and would love to commit to a fuse block solution.

[mb911]

This is a very cool project.. I would be interested.

[Larmo63]

I'm glad there are people in this world who are smart enough to know this stuff.

I have my own skill set, and I'm really good at Jeopardy, but thank you for making me feel like a complete nincompoop.

[mepstein]

I'm glad there are people in this world who are smart enough to know this stuff.

I have my own skill set, and I'm really good at Jeopardy, but thank you for making me feel like a complete nincompoop.

I had a great feeling of accomplishment when I screwed the shift knob Zach had made for me, into the rennshifter lever. Righty tightly, lefty loosey.