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Discussion Starter #1
My '93 900SS needed a new rectifier/regulator so I decided to go with the newer Mosfet type. In the process of finishing the R/R install, I ended up showing my son, in haste, what NOT to do by reinstalling the battery backwards and POP!. After replacing the blown fuses and correctly hooking up the battery, I kept blowing the ignition fuse. Thanks to Punch and others in this forum, I decided to cut the shrink wrap, and lo and behold, I found the fried diode at the solenoid connector.



I heard of others talking about how they just replaced it (1N4007), but how? Is there a special tool to remove the female pins from the connector? Are the pins locked in forcing me to get a new part at the dealer? This should not be that complicated, but I am getting frustrated, but I don't want to hack the connector up.

Thanks for any help on this one.
 

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You can try a very small screwdriver to press the pin lock in the connector, but depending on the connector a better option is to look for a set of pin extraction tools on line at like Amazon. I bought a set by OTC that was pretty cheap and has 6 extractor tools for most pin types. Of course Murphy's law says that when I go to use it I still won't have the one extraction tool I need. You will also have to get the correct spare pins for the connector and a tool to crimp them. Good crimp tools are expensive. Is there a manufacturer's name on the connector?
 

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Discussion Starter #3
Thanks for your ideas. I've looked at the connector for any kind of reference, but there is no labeling except for a "1" and "2" in the back to signify wire position. I have no idea whether it is a molex or amp type of connector or even if the pins are standard. Pin extraction for the female/barrel side usually has two little wings that need to be bent in to remove it. I looked closely, but the barrel has no indication of these locks. Still attempted to push the wings in anyway to no avail. Also, tried to "unlock" the pin from the wire side, but that got me nowhere.

We have a Frys nearby so they might have an extraction tool and replacement pins, but I'm not sure if the computer connectors use the same pins as in this connector. It would be great if someone had attempted this before to know what tools will work.

My last resort is to clip out the diode, but leave enough wire to solder the new one to each end. I prefer to do a cleaner job, but if the pins are locked, I may not have a choice.
 

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If I were you, I'd just clip it out, and solder in a new one... Easier and cheaper than sourcing a pin removal kit, and new pins, and a crimping tool. Just wrap it well in insulating tape when you're done.


While we're on the diode topic - does anyone know exactly WHY it's there in the first place? I seem to have missed the conversation on this topic. :eek:

I first noticed it (the diode) on mine when I had to replace the solenoid. It had failed, so I used a Yamaha unit, which has a different plug, but I left the original plug in place, as I thought it (the diode) was part of the alarm/immobiliser that I had fitted at that time. Since then, I've removed the alarm/immobiliser - but can't remember if I removed the diode or not - possibly not, as the original plug was well wrapped in insulating tape... If I did remove it - it doesn't appear to have affected anything. :confused:
 

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It probably is easier to just clip out and solder a new one in. What circuit is the diode in? I can't find it on the wiring diagram.
 

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It probably is easier to just clip out and solder a new one in. What circuit is the diode in? I can't find it on the wiring diagram.
It sits between the two terminals of the plug that fits into the starter solenoid.

Hmm - that's interesting - my Haynes manual shows it on the solenoid in the wiring diagram for the Monsters (all sizes) - but not for the 91-93, and 94-96 SS/SL (all sizes) wiring diagrams.
 

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If I were you, I'd just clip it out, and solder in a new one... Easier and cheaper than sourcing a pin removal kit, and new pins, and a crimping tool. Just wrap it well in insulating tape when you're done.
Using other words - snip/cut the diode out as close as possible to the diode and use the remaining diode wires to solder in a new one - observe which way the band at one end of the diode goes and solder the new one in the same way.

Spacey - it is across the starter motor solenoid coil.

While we're on the diode topic - does anyone know exactly WHY it's there in the first place? I seem to have missed the conversation on this topic. :eek:
Rather than write out the theory, read pages 5, 7, 11 and 12 in this link.
The diode is there to protect electronics in the bike from high, induced, reverse voltage spikes when the solenoid coil is de-energised.
http://www.autoshop101.com/forms/hweb2.pdf

After reading that you may wonder - why don't all the relays/solenoids have a diode across their coils?
The starter motor solenoid is a large relay. Being larger, to switch more current, the coil is bigger and the magnetic field will be larger/stronger, so when it collapses, as per the link, much more energy (potentially damaging) is "released".
 

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That purpose makes sense. Looking at the coloured diagram that Punch has sent out in the past, I don't see a diode in the starter solenoid circuit. I'll go look at my bike. I once stupidly put the battery in backwards and nothing bad happened. Perhaps its because that diode is not on my '92 900 SS or perhaps its because I noticed the error before I turned any switches or pushed any buttons.
 

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Discussion Starter #9
Snip and solder looks like the only answer at this point. It seems to me that those female pins are slotted so that the can squeeze through the gap and spring open on the other side. Without the traditional wings on the barrel, I am more convinced that it is meant to be permanent. Plus, you are right, the diode is not found in the wiring diagram and anywhere else in the Haynes manual for my '93. Not even the more detailed parts catalog with exploded views of the assemblies. Thanks to the forum I would have not even known about it.

Another option would be to strip some insulation off each wire and just crimp each end of the diode to the wire, but I would be concerned about exposing any of the wiring and creating a short. Soldering will work only I will have to be careful not to overheat the diode. From what I have read, it's best to pre-tin all the ends and join them with a quick melt.

I'll try to take care of this over the weekend and let you know how it works out.
 

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If you have a small alligator clip, attach it to the diode lead where it enters the body prior to soldering. This provides a heat sink. if the connector and wires are still good, and the leads of the current diode are exposed, you could clip the body off the old diode and solder the new diode onto the exposed leads.
 

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Discussion Starter #12
The replacement connectors you link to are not for my model ('93 900SS). They are blade connectors that lock in the middle of the connector housing. Mine has two female barrel connectors that plug straight into the solenoid, which is different from the picture. I don't think mine are blade-type connections, but I can double-check again. I did try to pull the wiring from the end of the connector and was pulling pretty hard, but there was no way I wanted to push it and yank the wire from the crimp.

It was worth a shot, but these are for an R/R and do not have the correct shape or connectors to match my solenoid.
 

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Using other words - snip/cut the diode out as close as possible to the diode and use the remaining diode wires to solder in a new one - observe which way the band at one end of the diode goes and solder the new one in the same way.

Spacey - it is across the starter motor solenoid coil.

Rather than write out the theory, read pages 5, 7, 11 and 12 in this link.
The diode is there to protect electronics in the bike from high, induced, reverse voltage spikes when the solenoid coil is de-energised.
http://www.autoshop101.com/forms/hweb2.pdf

After reading that you may wonder - why don't all the relays/solenoids have a diode across their coils?
The starter motor solenoid is a large relay. Being larger, to switch more current, the coil is bigger and the magnetic field will be larger/stronger, so when it collapses, as per the link, much more energy (potentially damaging) is "released".
Thanks for that Punch. I knew about surges from big motors starting up - but hadn't ever considered the problem from relays/solenoids. The relays that I worked with back in my Telecom days were all in non-electronic systems - and that was also so long ago, that even if we were using diodes across the relays - I'd forgotten why... :eek:

Damn - now I'm going to have to go and unwrap the tape off the original plug, and check if I left the diode in or not.
 

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The manual and wiring diagrams we are using are quite old and probably copies of the originals.

Often, not just for Ducati, Technical Bulletins are issued to sort problems/issues and given the scarcity of even original info, it is unlikely that we would come across info that includes all updates/modifications to original stuff.

BTW - the collapsing magnetic field and associated high voltage is part of the reason why ignition coils provide a very high voltage to the spark plug to make it spark.
 

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The replacement connectors you link to are not for my model ('93 900SS). They are blade connectors that lock in the middle of the connector housing. Mine has two female barrel connectors that plug straight into the solenoid, which is different from the picture. I don't think mine are blade-type connections, but I can double-check again. I did try to pull the wiring from the end of the connector and was pulling pretty hard, but there was no way I wanted to push it and yank the wire from the crimp.

It was worth a shot, but these are for an R/R and do not have the correct shape or connectors to match my solenoid.
Sorry - the link is for 3-phase connectors. You've got 2-phase. Eastern Beaver is a good source for connectors.
 

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Discussion Starter #16
Just to close the loop, I ended up soldering the new diode in place. Cut the old diode, sanded the remaining wire/diode ends, tinned all 4 ends, and then joined them with a quick hit of the soldering iron. Rechecked the diode and it tested ok. It could have been cleaner, but I did not want to transfer too much heat:



Oh, the best part was that it worked! My bike started up as it usually does. Thanks for all the suggestions. Unfortunately, the larger shroud of heat shrink didn't shrink tightly at each end, so I might seal it with some urethane glue when I update the starter/ground wiring later this year. Still riding season here in CA!

 
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