"Safety Relay" voltage question

[nhsteve]

Working on a '74 TX650A. Full rebuild, almost a restoration. The original wire harness was fried down near the rectifier area and so-called "safety relay" area, so I obtained a repro unit from the infamous Mikes'XS. Replaced battery with new Yuasa sealed unit (12.6+ vDC). Replaced rectifier assembly with NOS OEM. Regulator seemed ok (still does). Rebuilt/cleaned up the left & right handlebar switches. Ground off the paint for the grounds being used, etc. Was pretty thorough I think when I did all this. When I tested initially charging would go up to 13.5 vDc + before the regulator kicked in.
Had some shifting issues that 2M and others helped me with (shift drum cotter pin issue), but the bike runs strong and seemed all set after a few shortish rides. At the inspection station for a sticker the bike would not electric start (it had before ok). Kicked it to life and got home.

So this is what I am finding: I have battery voltage (12.5 +/-) to the yellow lead going to the "safety relay" (NOT the solenoid) whenever I have the battery connected. I believe after reading the starter FAQ section that this accounts for the electric start NOT working. The only way I can remove that battery voltage is to disconnect the yellow wire coming up from the alternator. I have virtually disconnected everything else (and I mean EVERYTHING else) from the system. Tried another alternator assembly- same thing. Another "safety relay"- same thing. I cannot figure out where I am getting the 12 volts.

I want to confirm that I should NOT have any voltage to that relay until I have the key on and the bike started. Am I right about that? I just don't recall ever hearing it come in like that before. Would like to condemn the harness, but it is new (I know, doesn't mean anything considering the source).

Any clues?

 

[retiredgentleman]

Yes, you should not have any voltage on the yellow wire, until the engine is running and the alternator is producing voltage.
I would say your rectifier is defective (NOS OEM???). One of the 3 phases has a shorted out diode. If you unplug the rectifier, the voltage on the yellow wire probably disappears. If you have the rectifier unplugged you can test each of the 6 diodes............each should have very high resistance one way, and very low resistance the other way.

 

[nhsteve]

Thanks for your reply and confirmation of what I thought I understood. I was starting to doubt myself and my basic understanding.

I will test the rectifier. It was/is indeed OEM, bought as new from eBay maybe? But the correct number on the box, etc. And the system did charge up ok when I first started the bike (one of my first tests).

Oddly, I still had that battery voltage on the yellow lead to the safety relay even with the rectifier, regulator, light checker (?), rear lights, and everything in the headlight disconnected (really). This evening I strolled by it, grabbed the DVM and found no resistance between that yellow lead and the red battery lead. Hmmmm.....

So that is my starting point for tomorrow. Find why there appears to be a dead short between that yellow lead and the positive terminal of the battery. I will report back.

Thanks again!

 

[5twins]

On your charging system, power is fed to the alternator from the regulator on the green wire to the outer brush. That's the only power feed to the alternator. But, the regulator is supposed to switch that power on and off to regulate the charging output. It sounds like yours is on all the time. Try unplugging the regulator and see if the power on the yellow wire disappears.

 

[nhsteve]

08/24/16 morning update-

No joy this morning. Tested rectifier, still seems ok (diode test on DVM seems normal to me).

I have unplugged and thus removed entirely from the system:
The rectifier, the regulator, the main switch, left and right handlebar switches, meter assembly, front brake switch, horn (basically everything inside the headlight bucket), as well as all the taillight & rear turn signal leads (just because), the safety relay, & the starter motor lead from the solenoid.

With just the alternator stator plugged in, as soon as I connect the battery (immediately, in other words), I have +12 vdc at that yellow safety relay lead. No switch involvement at all. Pretty much bare bones electrically speaking.
If I remove the single yellow lead at the stator lead (it actually goes to that yellow safety relay lead), the voltage is removed. With the stator connected I have a direct path (zero resistance) from that yellow lead to battery positive.

I have tried two other stators, one that was unknown, and one that I know was good last year from a '78, with the same results. I cannot believe that I have 3 bad stators in a row (especially as the '78 was/is a runner, just haven't started it this year), and am reluctant to spend money on a "new" unit only to find it does the same thing. Thinking now about the solenoid, and may take the one from the '78 and try that, if only to eliminate it.

I do have a new solid state regulator/rectifier combination available, but am reluctant to try that in case it gets damaged at this point.

I am seriously confused at this point. I will probably have to start removing even more bits than I already have to start doing an 'easter egg hunt'.

Comments?

 

[retiredgentleman]

That is all very strange indeed! However, you did buy a new wiring harness from Mikesxs, and everything they sell is suspect of being poorly made. You seem to have a short circuit between the battery + red wire and the stator, 3 white wires. All you can do is keep investigating.....................maybe start unwrapping the wiring harness.

 

[mrriggs]

08/24/16 morning update-

If I remove the single yellow lead at the stator lead (it actually goes to that yellow safety relay lead), the voltage is removed. With the stator connected I have a direct path (zero resistance) from that yellow lead to battery positive.

You said that the voltage is "removed". Does that mean that the voltage on the yellow wire from the stator was zero volts? What was the voltage on the yellow wire to the relay? If it shows 12 volts when unplugged from the stator then the problem is in the relay or wiring to the relay.

 

[nhsteve]

Problem source found. I was afraid of this.

Another fried harness, in exactly the same location as the original, down by the rectifier and safety relay, tucked away behind the right airbox. Pics attached.

I found the original harness really fried in this area, which prompted me to replace the harness ($61 + shipping from Mike'sXS) during the rebuild. The original rectifier was indeed bad, so I obtained a new one from a vendor. I have retested it now twice, and it does bench test (per the Haynes manual anyway) to be ok. Am using a DVM with a diode test setting, I get open (infinite) in one direction and small resistance the opposite direction on all 3 diodes (essentially the same values). So at this point I am thinking that is ok, and yet that is the physical area of the heat damage.
Testing the alternator leads, the 3 white and 1 yellow, all four show zero resistance, which I think is correct. At least, that is the same reading I get on 2 other stators I have available to me (and I strongly believe at least one of them is good, from a running '78).
So at this point I am going to rebuild the harness between the rectifier plug and the stator plug only. I have or can get the bits I need for that task. That way I can separate out the 3 circuits in that area into one to the rectifier, one to the safety relay, and the last to the rear brake switch.
So far WRT the charging function, I have only replaced the rectifier, so something else is causing this wiring to get hot and melt together. I hav another bike that I can 'borrow' from, and may start with the regulator, then safety relay, then finally the stator.

And if none of that works, it's back to the start again, I guess!

 

[nhsteve]

Adding this just to show the quality of the Mike'sXS harness. Note that the red (+12 vdc, therefor the hot lead) has neither solder, tape, or shrink wrap on the splice. This was as found inside the harness after I unwrapped the covering to further expose the heat damaged leads. This harness arrived in an unopoened bag, and was missing the 3 lead white plug for the safety relay. This was not a problem at the time, as I removed it from the old harness and moved it onto this one.
I am not claiming the red lead being like this caused the damage, but it does show up a lack of QC.

 

[retiredgentleman]

You said you have tested the 3 diodes OK, but there are 6 diodes in a 3 phase rectifier. Have you tested all 6 diodes? The stator white leads don't have 0 resistance, they have about 0.5 ohms, but that can appear to look like 0 resistance. Its very hard to measure resistance that small, because your meter leads can have resistance around 0.5 ohms as well.

Yes, Mikesxs has a reputation for selling poor quality parts, and your harness continues that reputation. I like your persistence and determination to solve and repair problems as they pop up.

Certainly give the rectifier a thorough testing again, to be sure all 6 diodes are good. You must still have some hidden short circuit in that harness if the rectifier tests OK.

 

[nhsteve]

On your charging system, power is fed to the alternator from the regulator on the green wire to the outer brush. That's the only power feed to the alternator. But, the regulator is supposed to switch that power on and off to regulate the charging output. It sounds like yours is on all the time. Try unplugging the regulator and see if the power on the yellow wire disappears.

I think 5twins had it. Have been busy with other projects (my son's car mainly), but late last week I dove in again and double checked the rectifier. Retiredgentleman is of course correct about the number of diodes, and I did a re-check of the new rectifier according to my Haynes manual, and it checks out fine. Infinite (open) in one direction, and 0.489 ohms to 0.498 ohms for all diodes. So I think that is fine.
While I did not do exactly as 5twins suggested, while I had the manual open and the procedure for checking the regulator was, well, right there, I decided to check it. I found the regulator did not pass that test at all. In the normally closed position (of the regulator relay) I had exactly the same resistance (about 10 ohms) as I did in the 'active' position. So I think I had an excess current flowing there, which heated up the harness.

I've cleaned up the contacts, and now in that normally closed position I have a nominal 0.2 ohms at best. About 8 ohms in the middle, with just 10 ohms closed. My plan is to replace just the leads between the rectifier plug and the stator plug, as these are the damaged ones with 18 gauge wire from HVC cycle. I'm going to separate out the leads to the safety relay and rear brake light switch so I have 3 small harness sections instead of just one larger one so I can control any further damage if I'm wrong. Put things back and test it out. Hopefully I will not have the safety relay pull in with battery voltage, and it will charge properly and electric start correctly.

Will report back next week with an update and hope to close this one out.

Appreciate all the help guys!

 

[retiredgentleman]

With the XS650 its somewhat common to find evidence of excessive high current flow in the rectifier area. Plastic multi-pin connectors melting, and as you have found, wire insulation melting. I believe that most of the problem is due to the mechanical regulator, springs and relay contacts going out of calibration, and causing higher than normal current flow. While the mechanical regulator is a crude device, it stayed within calibration for 20 or 30 years or more; but eventually they go out of calibration and high current flow is the result.

By cleaning contacts, you may get the regulator to work better temporarily. 5twins has a diagram that shows how and where to re-calibrate the regulator, but again I don't think it would be a lasting repair.
I simple solution is to replace the OEM mechanical unit with an automotive NOS VR-115 regulator. They are inexpensive, heavy duty
and maintain the voltage around 14.2 volts.
It seems a waste of time and effort to try to make an old mechanical design work, when much better, inexpensive parts are available.

Edit: I would not use 18 gauge wire. I suggest using minimum of 16 gauge.

 

[5twins]

Yes, there is a points gap and what's called a "core gap" inside your mechanical regulator. These need to be checked and possibly re-set to the provided specs. If your gaps are too small, that might explain why the unit is turning on easier and quicker than it should. Here's the adjusting details .....



But, even properly adjusted, this old mechanical regulator doesn't work very well. It's output is very inconsistent. The voltage output it requests from your rotor and alternator is constantly bouncing up and down, even at higher RPMs. Failed rotors are kind of common on these bikes. I think this antiquated mechanical regulator contributes to that, working the rotor harder than need be.

I fooled with my old mechanical unit a couple times over the years, adjusting it's output higher. It's pretty simple to do and to check the output at the battery. But, that doesn't show you how inconsistent that output is. I now have a color changing L.E.D. charge light installed. That actually showed me how the charge rate was fluctuating up and down. It glows orange below 13.2V, green above. It would go green by about 2K but randomly revert back to orange by about 3.5K and above. Since I installed the VR115, it goes green and stays green, until I drop back down to idle of course.

 

[nhsteve]

Thank you both, 5twins and retiredgentleman!
So, now I am re-thinking this whole thing again (still working on my son's car during all this- thought he was all set (had been doing body work on it) and he took it Sunday afternoon, only to limp home with the check engine light on and a faulty coil pack- will it ever leave??).

My overall goal with this of course is to have it be a reliable bike to ride. Originally my plan was to get the bike going, do some short break-in type mileage just to see that all systems functioned correctly, and then replace the rectifier and regulator with a solid state combined unit, which I had at the ready.

In your opinion, should I get one of the NOS VR115 regulators and just use that with the new rectifier (which I am 99.99% positive is good)? Also, regarding the wire gauge, I can get 14 gauge from the hardware store. Wasn't sure I could get that into the plug itself. Could I use that, or hunt for 16 gauge?

Really appreciate the help guys!

 

[retiredgentleman]

IMHO the VR115 is the best way to go. Use 16 gauge stranded wire.

 

[nhsteve]

Wanted to close this thread out with my 'final solution', and many thanks to 5twins and retiredgentleman for their insight and assistance.

I obtained some 16 gauge automotive wire locally, and replaced the 5 leads going to the rectifier (I have the correct crimper and ends). 3 whites, 1 red, & 1 black. The black (ground) I found going to another twisted set of black leads going to the regulator and tail section of the bike. I think there were at least 4, maybe 5 leads total, just twisted around each other, non-sticky tape over the whole bundle (also kinda loose).
I pulled these apart and then proceeded to solder them successively into as nice a bundle as I could. I then spliced one of these into the 16 gauge lead (new) from the rectifier, which I added a 6mm eye end to and then to a bare metal ground point on the frame.

With "cleaned up" regulator I started the bike and saw battery voltage rise past 15.5 volts before I throttled back. So I knew at that point that I was at least charging. (Even though a charging check was one of my first tests, & it seemed ok,I was skeptical of that function) So I went ahead and installed the Oregon combination rectifier/regulator. This proved to be what I was looking for, as it would charge up to and then limit at 14.4 vdc. Good enough for me I thought. So things went back together and I took it for a 50 mile test ride without any issues. I think I can move on here to the other small issues I have on the bike before I hand it over to my son (it was always supposed to be his anyway).

So thanks to those who commented and helped out, it is very much appreciated.

In case anyone wants to know, I got the solid-state rectifier/regulator from Oregon Motorcycle Parts in Willamina Oregon. He was very helpful, and supplies both these units and more (connections, etc.) for a Lot of Japanese stuff (I noticed a lot of Honda bits). Website: http://www.oregonmotorcycleparts.com/index.html

Lastly, wanted to share a pic of the bike as she sets now. Thanks again guys!

 

[retiredgentleman]

You have done an excellent job on that bike! Should be a reliable and fun bike