Hi I have a jd 490E excavator and having problems with the changing system Does any one know the value of the alternator resistor? It's located in the cab and drops the voltage to the field terminal of the alternator The schematic I have calls it R1 ALTERNATOR RESISTOR but does not show the value. Thanking everyone in advance Joe
Is it in a area in which you are able to take a photo of the resistor?
Yes it is but that doesn't help because the resistor is open and the markings are not legible. Got to find someone that owns the machine or has a parts list that may state the value. The location is on the left side behind the seat left when you are sitting in the seat Do you happen to own a 490E
I don't think it's terribly fussy about the value, something like 10 ohms to get 1 amp should work. If it doesn't charge, or doesn't shut off with the key, or doesn't turn out the battery light, then I was wrong.
Welcome to HEF Joeh Alternator excitation resistor is part # 4191772 . I could find no resistance specs. . HEF member @joelx777 is currently wrenching on a 490E, maybe he could help you out. Also @mg2361 has access to Deere‘s “Parts Advisor” program, he could likely help you out with a resistance spec.
Please refer to him as Deere God
Hi Delmer this is a 24 volt system and I know it's 10 watts. The battery light is on and the alternator is not charging. The field excitation is missing because the resistor is open. Your saying the alternator field needs 1 amp. That should be about 20 to 25 ohm Those that sound right?
Thanks Dave I'm new at this how do I contact members 108212 and 57398
Hello Deere God I'm told you might be able to answer my prayers But I'm not sure how to get in touch with you hopefully you will read this Thanking everyone for the help Here goes
Send them each a message. I hi-lited the message box in the screenshot below.
Thanks again
Unfortunately, Deere's Parts Advisor does not give a spec on that, nor can I find any spec in the service manual. If you know it is open, then just buy one from Deere. I know it is pricey ($72), but it will get you going. Like Dave said, maybe @joelx777 [/USER] can help if he has access to measure one for you. The only information I found is the voltage gets dropped to about 3-4 volts before entering the excitation of the alternator. This early in the morning will hurt my brain trying to figure what resistance you need. So, I'll leave that to you to figure out.
We'd need to know the amperage, or resistance of the voltage regulator to see what resistor value would drop it TO 3-4V. You said 10W above, and I'd figure it out from that, but I'm guessing that's the rating of the resistor, not the actual operating value, so that would just muddy the waters more. I'd try 10-20 maybe even up to 30 ohms and see what it does.