I have a B7100. The tractor is in great shape but the engine got very tired. I recently found a used low hour D850 engine too good to pass up. The tractor had a D750 in it. The D750, D850, and the D950 are all the same block just different bores. The engine is in and runs good but, I still have a problem. The D750 had a dynamo and the D850 has an alternator. The Dynamo and the Tractor has three wires, white, brown, and yellow. The alternator has two blue wires. Any ideas? I ane done some research and found the following models to use the same alternator as is on my D850: B1550, B1570, B2100, B2150, B2400, B7200, B7500, B8200, and B9200. Any body hane electrical schematics of these models?
B7100 Dynamo to Alternator change
- Thread starter TAG
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Soundguy
Old Timer
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wHY CAN'T YOU SWAP THE ALTERNATOR AND ASSOCIATED ELECTRICALS OVER FROM YOUR OLD ENGINE. IF IT REALLY IS THE SAME BLOCK.. SHOULD BE ABLE TO BOLT THE MOUNTS RIGHT UP RIGHT?
Sorry for the caps.. key was stuck!
sOUNDGUY
Sorry for the caps.. key was stuck!
sOUNDGUY
normde2001
Elite Member
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"The D750 had a dynamo and the D850 has an alternator. The Dynamo and the Tractor has three wires, white, brown, and yellow. The alternator has two blue wires. Any ideas?"
Using the dynamo and existing wiring from the old engine on the new engine should solve the problem, no rewiring.
Using the dynamo and existing wiring from the old engine on the new engine should solve the problem, no rewiring.
What I failed to mention is that the old engine withe dynamo did not have a water pump. It used gravity flow system, and the dynamo was located behind/under the fan pulley. the new engine has a water pump and therefore I cannot use the dynamo. The new engines alternator is located where the old engines fan bet tensioner pulley was. Still looking for a solution. Thanks, TAG
Jagmandave
Veteran Member
Without looking at it, sounds like the three wires go to the generator regulator, hot, ground and field. The alternator may have a built in regulator, in which case the two blue wires simple go to the battery or to the "batt" wire connection at the old regulator. You might take the alternator to a local electrical shop and ask them if it has a built in regulator if you can't ascertain this for yourself. if it does, you're golden. if it doesn't, you need an alternator regulator and instructions to wire it up - the electrical shop should be able to provide both.
Good luck!
Good luck!
