Overheating issue

[Big T]

My fuse box overheated

IMG_20190805_195749605 by Todd Cannon, on Flickr




IMG_20190805_195819999 by Todd Cannon, on Flickr

The main fuse holder melted into the plastic case and the solder on both sides of the main fuse melted and ran down onto the headlight fuse and the circuit buss, causing the headlight and oil pressure light to stay constantly lit, even when the key was off.

Now, I had been maintaining the separate regulator and rectifier that came stock (because I want to return the bike to stock), also, it worked fine for the last 41 years. However, weird voltage readings and a discharged battery *which charged up fine) lead me to install a SH 775 I had for another bike

After installation of the new R/R, voltage was 12.6 at idle and 13.4 at 4,000 rpm.

I know resistance causes heat, but my voltage tests at the headlight and tail light come out just over 12 V. I cleaned the ignition switch as a part of checking the weird voltage issue, so I'm puzzled as to where the resistance issue is located. This happened only 300 miles after installing the 775.

Any ideas?

[Brendan W]

At a guess the fuse holders are corroded or the fuses themselves have bad contacts between the fuse link and the end caps.
You can feel temperature differences between the ends with the bike running.
Speculating further the old set up was not charging properly and the 775 sent extra current through there.
Your voltages are about a volt too low.
Suspects would be drops on the positive and negative lines from the r/r to the ground point and the harness injection point.
If the ground strategy is still through the frame it could also account for the r/r seeing a false ground i.e. not the lowest system voltage and undercharging the battery. That is one of the motivations for a single point ground.

[cowboyup3371]

I would recommend just looking over all of your connectors and cleaning/replacing any as necessary

[Redman]

What did you do about the fuse block?
Obviously need to clear out that solder bridge. And resolder the 3 connections there that appear to have melted some of the solder.
AND find the cause of the heat, yes, current thru resistance equalls watts of heat. Probably the fuse connector corroded where the fuse plugs in. SO clean that up.
Or maybe just get a replacement fuse block. Will need to be the type that has the harness going to a connector like you have.

I would say a lot of you voltage drop(s) are right there in your fuse block.

[Gorminrider]

Get rid of it. get a new fuse block with screw connections. Crimp lugs to wires and attach.

Trying to solder to those large surfaces has probably gotten the copper wire too hot and brittle-ized the wires so the strands break...when you heat copper to red and cool it slowly it HARDENS it. (opposite to steel). if you must solder it, you need to tin each side heavily before melting together and even then, the bond is no improvement on a crimp connection. worse mostly...cars don't solder everything. The bike came with crimped connections ...it's hard to find solder anywhere except small bits...where the surface area is small and a cool iron can heat everything up enough before the copper is ruined..

[posplayr]

Tod, That is a crap fuze box but if you want to keep it you should:
A.) clean it well with naval jelly
B.) then get some Flux and reflow the solder joints (50+ watt soldering iron). What you are are all cold solder joints from some ones prior attempts.
C.) Then spray with Deoxit including the newly replaced fuzes.

https://www.thegsresources.com/_forum/showthread.php?237763-Recommended-Products-for-Preparing-Electrical-Connenctions&highlight=contact+cleaner

[allojohn]

Welcome back Jim.

[Brendan W]

Jim can smell a bad connection at a thousand yards

[Guest]

Or install a SSPB!

[Big T]

Tod, That is a crap fuze box but if you want to keep it you should:
A.) clean it well with naval jelly
B.) then get some Flux and reflow the solder joints (50+ watt soldering iron). What you are are all cold solder joints from some ones prior attempts.
C.) Then spray with Deoxit including the newly replaced fuzes.


https://www.thegsresources.com/_foru...ontact+cleaner

Jim,

It's a bit hard to see, but the plastic melted on the downstream side of the main fuse, so this box is trashed

I had cleaned the fuse contacts within the last year. The headlamp fuse connection (left, 2nd from top) that melted now has previously melted the solder joint a bit, so I had my friend resolder it. He's a QC tech in the local electronics industry, so he knows soldering inside and out. I cleaned the fusebox and cleaned all the connections around the airbox, plus replaced the 4 prong plug for the fuse box. So, I am surprised to find this melt down

I'm finding a 1 V drop from the main fuse/ignition switch/fuse buss circuit, but steady voltage on the 3 circuits -headlamp-ignition-turn signal

So, should I be checking amperage, or resistance on the various circuits? or both?

I have several more fuse boxes, so I have one in place to do my testing

[Redman]

Sounds like you have a good understanding of current thru resistance equals heat. Although in case of our bikes wiring the heat (and voltage drop) is almost always not related to excess current (unless have added extra lights or something), but mostly due to excess resistance, typically coorosion on connectors. Either the mating surface of the connectors or where the connector is crimped onto the wire conductor. That is my experience.

hey, you mentioned the wire conductors getting brittle due to heat. That is something I noticed, and I have also noticed that once the wire is brittle the. The crimp connections don’t last long, especially the common cheap crimpers. But even the better crimpers make a crimp that last longer but is still subject to loosing up on brittle wire .
since you seem to understand it from a metalergy point of view, tell us more.

[posplayr]

Jim,

It's a bit hard to see, but the plastic melted on the downstream side of the main fuse, so this box is trashed

I had cleaned the fuse contacts within the last year. The headlamp fuse connection (left, 2nd from top) that melted now has previously melted the solder joint a bit, so I had my friend resolder it. He's a QC tech in the local electronics industry, so he knows soldering inside and out. I cleaned the fusebox and cleaned all the connections around the airbox, plus replaced the 4 prong plug for the fuse box. So, I am surprised to find this melt down

I'm finding a 1 V drop from the main fuse/ignition switch/fuse buss circuit, but steady voltage on the 3 circuits -headlamp-ignition-turn signal

So, should I be checking amperage, or resistance on the various circuits? or both?

I have several more fuse boxes, so I have one in place to do my testing

The top three (O and R) solder blobs are all cold joints and probably have corrosion under them which is why they got hot!

QC is not a qualification for soldering.

[Big T]

Jim, I know about QC but, since he dates back to when things were soldered, he was trained in soldering.

Think Tektronix oscilloscope s circa 1978

[Gorminrider]

Redman, you don't have to rely on my mad ramblings-you can just go out and look under the hood of your car and look for solder in it, if you think Suzuki didn't know how to connect things...you need include GM, Honda, Toyota...

otherwise, rambling,
I just look at that old discoloured bit of brass and an 18 gauge stranded copper wire and I see trouble...apart from the zinc that is... a story:

"hmm ..sure takes a long time to get hot. And the solder just rolls off it...I'll sand it...aha solder finally sticks after polishing it! now I'll just hold this 18 gauge stranded wire (each strand being TINY in diameter) in the puddle...darn. Gotta remelt the puddle and the soldering iron is getting stuck too! Hold it on there... It still doesn't stick- turn up the iron maybe-the wire's kind of black too all those little strandlets getting splayed...(those little strandlets are screaming hot! resin is burning! carbon...)oh well, keep on with the iron that'll do it...ah, finally-that looks ok...now I want to put it back in the bike- darn it! It won't sit flat... I'll just bend this stranded wire a little more to fit it right to screw it down... hard to bend- the solder wicked right up the wire, where the sheathing melted..."

So , if the copper strandlets have been "tempered" brittle, and the strain relief doesn't exist any more because the solder wicked so far up the wire, and the solder is porous where the carbon floated out....how is this better than a crimp or, for that matter, creating an eye of the wires end and screwing it to the brass like 10 billion light switches have used happily over a hundred years...

[Big T]

Well, a bunch of resistance testing led me to the ignition switch. I know I took it apart and cleaned it a few years back, but the damage is obvious

IMG_20190811_162642701_HDR by Todd Cannon, on Flickr

IMG_20190811_162630227_HDR by Todd Cannon, on Flickr

The left (overheated) plate in the top photo corresponds to the two lower copper studs in the lower photo. The plate was replaced with one from a spare switch, and the studs were wet sanded with 2000 grit until smooth. Voltage drop between the main fuse and the others is now about .5 V, instead of 2 V

Road testing with tools and fuses to follow