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Subject: 8N voltage regulator

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Scott Leber    Posted 11-09-2021 at 17:24:54 [URL] [DELETE]        [Reply] [Email]  
  • 8N voltage regulator
  • 8N voltage regulator confusion, I have a late model 8N (side mount distributor), the voltage regulator on the tractor is not working and I need to get a replacement, from what I can determine I need a 8N-10505C "A" circuit,6 volt, positive ground. my generator has a 20 amp 6 volt output rating. All the replacement regulators (that claim to be replacement VR) that I have been able to find state there amp range is 10 to 12 amps. If I have a 20 amp generator I think I need a VR that can out put 20 amps?

    Scott Leber    Posted 11-30-2021 at 22:44:47 [URL] [DELETE]        [Reply] [Email]  
  • Re: 8N voltage regulator
  • I am not able to get the tractor to charge, I have taken the generator to a rebuilder to have it checked out, rebuilder stated generator works correctly, I changed the regulator that was on the tractor with a new regulator still on voltage charge, got another new voltage regulator still no voltage charge, put a new wiring harness on the tractor still no voltage charge.
    Anyone have any thoughts on how to get the tractor to charge!

    carl    Posted 11-10-2021 at 07:13:17 [URL] [DELETE]        [Reply] [No Email]  
  • Re: 8N voltage regulator
  • There has been a lot of talk in recent years of VR's being junk. Some probably are, depending on where you buy from. Dennis Carpenter and Just8Ns would be my first go-to place for parts. The late 8N (side mount dist) would use the 8N-10505-C VR so you have the p/n right. But, how do you know your current VR is bad? Incorrect wiring accounts for 99.98% of all non-starting issues. In other words the true root cause of the problem many times turns out to be mucked up wiring in the circuit. Do you have the belt tension right with the OEM tensioner? The late 8N GEN is a 20A, 3-Wire, A Circuit Unit. Did you motor test it? Have you gone thru the entire wiring system to verify continuity? Wiring and batter cables right and tight? That includes the VR being wired correct with ARM BAT FLD connections all correct. The GEN connections get backwards as well. Some later GENs stamped the terminals on the GEN barrel. The ARM is always the rear panel connection. The FLD and GND terminals often get revered and will not work. I've worked on a few guys VR's who had the connections backwards too. The first thing I look at when a guy has a 'supposed' fried VR is the setup and wiring. Is there a belt tensioner on the GEN? Without proper fan belt tension, the system will never charge the battery regardless if a GEN or an ALT. 2nd, is the lighting wired right? Lighting kits were dealer options on the N's. Many fellas wire their lights wrong and they end up with electrical/non-starting issues. If you attempt to polarize the GEN via the VR and do it wrong, you can fry the VR like that. Polarizing the GEN via the VR -often guys do it with the power ON and that will cause a VR issue. So avoid rookie mistake #1 - don't guess as to what the problem is. Troubleshoot. get the FO-4 manual and be sure the wiring is correct. Disconnect the battery and the lighting system. Then start tracing wires.





    Tim Daley(MI)

    8N voltage regulator    Posted 11-10-2021 at 12:50:20 [URL] [DELETE]        [Reply] [No Email]  
  • Re: 8N voltage regulator
  • Thank you for your replay, it took me several weeks to find out most of what you have described, great job.
    I have checked continuity of all the charge system wire, confirmed the correct terminations, cleaned all the termination points with a brass wire brush, momentary jumpered Bat to Arm to polarize the system, to confirm generator out put I grounded the field terminal to the ground terminal on the generator (ammeter showed 20+ output) and checked the voltage at the armature termination on the generator (7.3 volts).
    The first new VR after being installed and polarized gave no output when I started the engine. the second VR after being polarized started by giving 10 amps and when I increased the engine it would bounce between 10 to 15 amps but after 3 or 4 minutes it stopped outputting.
    I took the cover off both the original and the second VR and did notice that the air gap between the cutout coil magnetic point and the arm for the contact point is at least three times wider on the second VR and the old VR that was on the tractor, not sure if that would make a difference.
    The other question is most of the 8N 10505C regs for sale claim 10 to 12 amp operation but the generator has a 20 amp rating? will the 10 to 12 amp work and give me full 20 amp range?

    JMOR    Posted 11-12-2021 at 04:39:51 [URL] [DELETE]        [Reply] [No Email]  
  • Re: 8N voltage regulator
  • IF they are honest, a 12A VR will not allow a 20A charge rate. A VR, of anything beyond the very early designs, regulate both voltage and current by modulating field current.

    Bruce(VA)    Posted 11-10-2021 at 01:45:05 [URL] [DELETE]        [Reply] [Email]  
  • Re: 8N voltage regulator
  • Call Derek at Just8N's.

    In the very unlikely event that any of those v/r's won't work, he will know.

    8N voltage regular    Posted 11-10-2021 at 12:52:13 [URL] [DELETE]        [Reply] [No Email]  
  • Re: 8N voltage regulator
  • Thanks I will call him

    Jack Bennett    Posted 12-03-2021 at 22:14:01 [URL] [DELETE]        [Reply] [Email]  
  • Re: 8N voltage regularor
  • I am certain that the difficulties you are having with your changing system is a problem shared, at one time or another, with nearly every other 8N tractor owner. Please post a follow up explaining what the problem was and how it was fixed. I am really vexed when someone feels that a problem is important enough to post on a forum,, feels it will be of interest to someone with the knowledge to help solve it, and then wastes the shared information by just ending their comments. I am interested if n how this problem was solved, and visiting a tractor forum is the first step in both meeting others with similar interests, and concurrently, fixing my tractor.

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