SH775 Install Questions

[Newell33]

Hi Guys

I recently got my 1980 GS750 back on the road. While doing a little more testing, I realized that I have a charging system issue. After reading some of the resources on here, I decided to go with the SH775 regulator / rectifier mod. When I dug into my bike, the stator wires were all three gray in color, and the previous owner had installed an S1002e aftermarket r/r on the bike. By the looks of it, this unit appears to be a shunt type r/r. Since my stator wires aren't yellow or multi-colored, I'm guessing it's aftermarket as well.

I tested the stator wires for resistance between each leg, and then to ground. Everything checks out ok. I then started the bike and checked AC voltage. At idle all three legs were around 25V, but at 4,000 rpm the voltage quickly jumps over to over 60V. Based on what I've read, I can assume my stator is good.

I ended up ordering a used SH775 off of eBay, and had the chance to install it today. I hooked the three stator wires directly to the three terminals on the left, and then hooked the power and ground terminals directly to the battery terminals. I also made sure that I had a good ground strap from the case of the r/r to the frame, and from the battery to the frame.

When I start the bike without the lights on, and let it idle, I get a reading of about 13.2 volts. When I rev the bike to 4-5000 rpm, I see a reading as high as 13.9V. My problem is when I turn on my headlight. With the light on, the voltage drops and drops slowly down to about 12.2 volts. Obviously at this point the system isn't charging, and my battery is draining.

At this point I don't know whether I've got a bad SH775 r/r, or if there's maybe something wrong elsewhere. In reading through the materials on this site, I don't remember seeing a test for the SH775. Is there a way to test this unit? I'm wondering if I've got a bad r/r, or if I should be looking somewhere else.

Thanks in advance for the help.

 

[kdo58]

is the 12.2 volts at idle or reved up to 4000rpm?

 

[Nessism]

12.2 volts at 4000 rpm with the headlamp on? If so that's low.

Your stator should make more than 60 VAC. A no load test is not perfectly reliable though.

The SH775 is most likely good. I'd suspect the stator before the R/R.

 

[Grimly]

I'd say you might have a bad stator leg under load.
This might be a job for three of your funny American light bulbs - 110V 60W, one each leg-leg and see if they all light up. They won't go full brightness, but they'd certainly glow a fair bit, if the legs are ok. Just to be ever more sophisticated you could put an ammeter in circuit for gits and shiggles to confirm things. To bring it up to date, a clamp meter could be employed instead.
Digital, schmigital - our grandpas were solving problems like this with spit and horse tacks.

 

[posplayr]

As Ed and Grimly have said the likely culprit is the stator, but then stators are somewhat difficult to test. However there are some fairly reliable tests. Go to Revised Phase B tests here. The main test you failed to to earlier is leg to ground tests at 5000 RPM. This is when you should have about 80 VAC and by testing to ground you are checking that the insulation can withstand that 80 VAC.

Go to Step #3

http://www.thegsresources.com/_foru...-Charging-System-Health&p=1138531#post1138531

Testing this at DC with the voltage output of an ohm meter is a poor test at best. Yes I know it is in the manukan and yes it is in the original stator pages but it is still a poor test as you will likely find out.


After testing the stator, if it is bad, you will want to change it out. Make sure you redo all the Quick test especially those where you run the bike to 5K RPM under load.

 

[Redman]

.....

When I start the bike without the lights on, and let it idle, I get a reading of about 13.2 volts. When I rev the bike to 4-5000 rpm, I see a reading as high as 13.9V. My problem is when I turn on my headlight. With the light on, the voltage drops and drops slowly down to about 12.2 volts. .............

If the voltage readings you are reported are measured at the battery (and at mid RPMs), it is possible that the charging system is putting out what it should, but you have a bad connection somewehere between the R/R and the battery where the voltage is dropping before it gets to the battery. And that is enough of a voltage drop that something should be getting hot.

If the voltage readings you are reporting are at the R/R, well, then suspect something wrong with the charging system. Something where it falters at higher rpms (higher voltage, higher current). Could possibly be bad connection between stator and r/r (did go stator directly to new r/r, or still using existing connectors to get to the new r/r?).
But more I would suspect the stator faltering at higher load, even though it seems good at the open circuit no load voltage test.

.

.
>later note:
Also where are you located? (don't need to be too specific)
Add that to your profile, will then show up in every post.

 

[Guest]

I help a friend install an SH775 this spring and it turned out to be bad. Can't remember where he ordered it from though. I was never able to find a test for the reg/rec either. We tested the stator and it was fine, I luckily had another SH775 here and threw that in, end of problem.

 

[Grimly]

First thing I did when my second 775 arrived was hook it up to the wiring of the previous install for a test. Thankfully, it was fine, but there's always the chance of a dud. When I was installing the first one, it occurred to me that I might be going to a lot of trouble to wire in a duffer, as I'd no easy way to test it then.

 

[d.loseth]

Hey, I don't mean to hi-jack the thread, but I have an install question as well. I have the SH775 RR now as well, hooking it up to a gs1100. The three left terminals aren't colour coded on the new RR but my wires are. Will it matter which wires go onto which of the three left terminals? The power and ground is colour coded.

 

[posplayr]

Hey, I don't mean to hi-jack the thread, but I have an install question as well. I have the SH775 RR now as well, hooking it up to a gs1100. The three left terminals aren't colour coded on the new RR but my wires are. Will it matter which wires go onto which of the three left terminals? The power and ground is colour coded.

All stator wires are interchangeable.....................

 

[Newell33]

I was finally able to troubleshoot my bike again this evening. I got my hands on another SH775 and swapped it with the first unit. The results were exactly the same, leading me to the conclusion that the stator is in fact bad. I pulled it out and took a look. I did see one pole that was a little darker than all the rest as shown below. From all the stators I've seen for sale at various vendors, the only one I've seen with the green material and gray wires is at Z1 Enterprises. I guess I can't really fault the stator since the bike did have a shunt style R/R on it. This question has been asked in the past, but what are everyone's thoughts on a replacement? I see cheap Chinese versions (Caltric?) for around $53.00 shipped, to versions up in the $140.00 to $150.00 range. With a good SH775 in place, what's the consensus on a decent stator available today at the lower end of the price range?

 

[posplayr]

Looks burnt, too bad you did not testing using the Modified Phase B test before you removed it. Now you are committed to replacement, but you can be "pretty sure" it is in fact gone.

This demonstrates teh uncertainty in the standard stator tests. They can only prove that the stator is bad, not that it is good.

I tested the stator wires for resistance between each leg, and then to ground. Everything checks out ok. I then started the bike and checked AC voltage. At idle all three legs were around 25V, but at 4,000 rpm the voltage quickly jumps over to over 60V. Based on what I've read, I can assume my stator is good.

 

[Guest]

Here you go. It's an Electrosport, it's either one of these or a Ricks. Either one will work and this one is half price!

http://www.thegsresources.com/_forum/showthread.php?231024-Electrosport-stator&highlight=

 

[tom203]

Hey, I don't mean to hi-jack the thread, but I have an install question as well. I have the SH775 RR now as well, hooking it up to a gs1100. The three left terminals aren't colour coded on the new RR but my wires are. Will it matter which wires go onto which of the three left terminals? The power and ground is colour coded.

No, it doesn't matter. Remember that those "three left terminals" get connected directly to three stator wires.
When you 're done, make sure you test your handiwork!

edit: the positive output is the one closest to the three stator inputs