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Mower Blows 20 amp fuse when PTO when PTO is engaged
#1
J
JeffNC
J
JeffNC
My Simplicity mower has started blowing the 20 amp fuse when my PTO is engaged. After reading many posts regarding this common problem to so many, I purchased and installed a new PTO clutch (expensive..$260), also a new PTO switch and inspected most of my wiring harness as best I could, with no worn insulation discovered. After my installation of the new PTO clutch and switch, the 20 amp fuse lasted for app. 50 feet of mowing from cold start then blew. I replaced 20 amp fuse, disconnected the PTO electrical connection at the clutch, started the mower and engaged the new PTO switch and the fuse did not ever blow, which might indicate that the wiring insulation and new switch is good but the new PTO clutch might be bad? I can't imagine that the new clutch is no good or needs an air gap adjustment already being a new OEM Briggs Stratton product, nor the new PTO switch is bad. This problem appears to be so common to so many people regardless of mower brand and model, that it seems these manufacturers cannot remedy such a common DESIGN problem to the masses! WTF? I thought about trying a 25 amp fuse but did not want to risk 'frying' my new $260 PTO clutch...Help please!! This is BS as it is such a common problem to so many!
#2
B
bertsmobile1
B
bertsmobile1
There are 2 ways to approach a problem.
Toss parts at it till it goes away or find where the actual problem is and rectify it.
A solenoid draws POWER ( Watts ) and it does not care how it gets them
So 12V x 10A or 6 V x 20A or 3 V x 40A is all the same to it.
However Amps = heat.
Heat = RESISTANCE
RESISTANCE = VOLTAGE DROP
VOLTAGE DROP = more AMPS to make the same WATTS
And thus the self feeding loop continues till the fuse can't take it any more.
Much like the self feeding loop of face book morons makes bigger & more face book morons.
9 out of 10 mowers that come in here have disgusting battery connections and in particular the ground connection
Next is the actual fuse holder itself which is not waterproof because cheapskate owners & Face Book whingers will not pay the extra 50¢ to get waterproof connectors so the factories no longer fit them.
A proper search of this site will find around 2/3 of the blowing fuses problems were fixed by replacing the fuse holder.
Half of the remaining were fixed by cleaning or even replacing the battery cables & connections.
FWIW I do around 300 service / repairs a year and am yet to need to replace a clutch but I have gone through several 50 packs of fuse holders .
You are correct about their being a conspiracy out there.
It is called a free market lead economy
So whoever makes a mower with the lowest Hp to $ ratio or the lowest blade inch to $ ratio will outsell all others and prosper while the factories that make high quality mowers that sell for a fair & reasonable price will bob along being just barely profitable while the family that runs them continues to believe in the value of making quality over cost or go bankrupt.
That is the conspiracy, got nothing to do with badly designed PTO clutched except in the narrow minds of the technically if not totally ignorant who make 99% of cyber space.
The chances of you getting a dud PTO clutch if you bought it from a mower shop is about the same as winning the lottery
The chances of you getting a dud PTO clutch if you bought it from an on line Amazon or ebay vendor is about the same as it raining on any particular day.
All of the reject PTO clutches that are made in CHina end up being sold on line cheaply, usually because they are faulty .
Toss parts at it till it goes away or find where the actual problem is and rectify it.
A solenoid draws POWER ( Watts ) and it does not care how it gets them
So 12V x 10A or 6 V x 20A or 3 V x 40A is all the same to it.
However Amps = heat.
Heat = RESISTANCE
RESISTANCE = VOLTAGE DROP
VOLTAGE DROP = more AMPS to make the same WATTS
And thus the self feeding loop continues till the fuse can't take it any more.
Much like the self feeding loop of face book morons makes bigger & more face book morons.
9 out of 10 mowers that come in here have disgusting battery connections and in particular the ground connection
Next is the actual fuse holder itself which is not waterproof because cheapskate owners & Face Book whingers will not pay the extra 50¢ to get waterproof connectors so the factories no longer fit them.
A proper search of this site will find around 2/3 of the blowing fuses problems were fixed by replacing the fuse holder.
Half of the remaining were fixed by cleaning or even replacing the battery cables & connections.
FWIW I do around 300 service / repairs a year and am yet to need to replace a clutch but I have gone through several 50 packs of fuse holders .
You are correct about their being a conspiracy out there.
It is called a free market lead economy
So whoever makes a mower with the lowest Hp to $ ratio or the lowest blade inch to $ ratio will outsell all others and prosper while the factories that make high quality mowers that sell for a fair & reasonable price will bob along being just barely profitable while the family that runs them continues to believe in the value of making quality over cost or go bankrupt.
That is the conspiracy, got nothing to do with badly designed PTO clutched except in the narrow minds of the technically if not totally ignorant who make 99% of cyber space.
The chances of you getting a dud PTO clutch if you bought it from a mower shop is about the same as winning the lottery
The chances of you getting a dud PTO clutch if you bought it from an on line Amazon or ebay vendor is about the same as it raining on any particular day.
All of the reject PTO clutches that are made in CHina end up being sold on line cheaply, usually because they are faulty .
#3
I
ILENGINE
I
ILENGINE
99% of the pto clutches get replaced because of mechanical failures (bearing failures, or wires getting pulled out when the anti spin tab breaks) The rest because they are either not bad, but people though it was. And in the cases where the clutch is bad majority of those never blow the fuse. They will take out the pto switch first by overheating the internal contacts, but will never blow the fuse. The only time the pto clutch will blow the fuse is in the case of a dead short to ground.
In this case I would be looking for a wiring diagram and found out what else is connected to the fuse because there could be something else causing problems but the clutch just puts it over the top.
In this case I would be looking for a wiring diagram and found out what else is connected to the fuse because there could be something else causing problems but the clutch just puts it over the top.
#4
T
Telesis
T
Telesis
As an electrical engineer for over 40 years, I want to provide a bit of clarification to what berts said about solenoids. All a solenoid consists of electrically is simply a coil of wire. It creates a magnetic field when, in this case, a DC current passes through it. The amount of current it draws is determined by the resistance of the coil, which is typically under 5 ohms for a PTO. A solenoid does not draw watts per se. It draws a specific current based on its resistance and the voltage applied. When you multiply the voltage across the solenoid by the current through the solenoid, you will know the wattage or energy being used. A solenoid may specify a wattage in its spec sheet, but that is only when the unit is operated at its rated voltage, and when it is cold. [as a side note, the resistance of a coil actually rises as its temperature rises, causing less current to be drawn]
A solenoid does not behave in such a way as to draw the same number of watts, regardless of the voltage applied. In other words, if you took a perfectly good 12V PTO clutch and connected it to a 12V battery, it will draw a certain amount of current(likely to be in the 3-4 amp range based on a coil resistance in the 3-4 ohm range). If you take that exact same PTO clutch and connect it to a 6V source, it does NOT draw twice the current. In fact, it will draw half the current. The power is also halved. Why? Because the resistance of the coil remains the same in both cases. Ohm's law still applies. Current=Volts/Resistance
Specific to your problem, I'd suggest using your ohmmeter and checking the circuit(with battery disconnected of course). Disconnect clutch and check its resistance first. If the value you measure is significantly below the 3-4 ohm level, then it would appear your PTO is hosed. If it's good, then I'd work my way back looking for short of some kind to ground.
I submit this with the deepest respect for berts and his extensive experience! Not trying to start a flame war, rather I just want to give Ohm's Law its due!
Keep us posted!
A solenoid does not behave in such a way as to draw the same number of watts, regardless of the voltage applied. In other words, if you took a perfectly good 12V PTO clutch and connected it to a 12V battery, it will draw a certain amount of current(likely to be in the 3-4 amp range based on a coil resistance in the 3-4 ohm range). If you take that exact same PTO clutch and connect it to a 6V source, it does NOT draw twice the current. In fact, it will draw half the current. The power is also halved. Why? Because the resistance of the coil remains the same in both cases. Ohm's law still applies. Current=Volts/Resistance
Specific to your problem, I'd suggest using your ohmmeter and checking the circuit(with battery disconnected of course). Disconnect clutch and check its resistance first. If the value you measure is significantly below the 3-4 ohm level, then it would appear your PTO is hosed. If it's good, then I'd work my way back looking for short of some kind to ground.
I submit this with the deepest respect for berts and his extensive experience! Not trying to start a flame war, rather I just want to give Ohm's Law its due!
Keep us posted!
#5
NorthBama
NorthBama
#6
T
Telesis
T
Telesis
Now I have to correct my own response!
In my example of connecting a PTO clutch to first a 12V source, then a 6V source, I indicated the power would be halved also. Not true, the power is 1/4 as much. Duh! Power=Volts x Current. Half of the voltage results in half of the current.
Example: Let's say PTO has a 3 ohm coil. Put 12VDC across it and it will draw 4 amps (12/3=4 amps). The power is 12 x 4 = 48 watts. Same PTO, but put 6VDC across it. It will draw 2 amps (6/3=2 amps) because the resistance is the same. The power is 6 x 2 =12 watts.
Current is half (4 vs 2 amps), while the power is one-fourth (48 vs 12 watts).
Sorry for the confusion. Time for another coffee!
In my example of connecting a PTO clutch to first a 12V source, then a 6V source, I indicated the power would be halved also. Not true, the power is 1/4 as much. Duh! Power=Volts x Current. Half of the voltage results in half of the current.
Example: Let's say PTO has a 3 ohm coil. Put 12VDC across it and it will draw 4 amps (12/3=4 amps). The power is 12 x 4 = 48 watts. Same PTO, but put 6VDC across it. It will draw 2 amps (6/3=2 amps) because the resistance is the same. The power is 6 x 2 =12 watts.
Current is half (4 vs 2 amps), while the power is one-fourth (48 vs 12 watts).
Sorry for the confusion. Time for another coffee!
#7
Fish
Fish
I get a self re-setting fuse for running down issues like this.
#8
NorthBama
NorthBama
nice i like it
#9
B
bertsmobile1
I can be just as wrong as the next person so never worry about correcting me it is always appreciated.
History ( well western history to be precise ) only records a single person who was never wrong & he got crucified for that.
So with a big mouthful of humble pie , I will still put money on a foul fuse holder creating a very high resistance causing the fuse to blow.
It is nothing odd to find wires on mowers corroded a dozen or so places along their length due to water wicking up under the insulation.
For that reason I never like to rely on resistance readings cause one single strand of good wire in an otherwise corroded through cable will ohm up as being good, till you try to pass some current through it.
For the same reason the test lamp in the workshop is connected to a headlamp globe
B
bertsmobile1
As an electrical engineer for over 40 years, I want to provide a bit of clarification to what berts said about solenoids. All a solenoid consists of electrically is simply a coil of wire. It creates a magnetic field when, in this case, a DC current passes through it. The amount of current it draws is determined by the resistance of the coil, which is typically under 5 ohms for a PTO. A solenoid does not draw watts per se. It draws a specific current based on its resistance and the voltage applied. When you multiply the voltage across the solenoid by the current through the solenoid, you will know the wattage or energy being used. A solenoid may specify a wattage in its spec sheet, but that is only when the unit is operated at its rated voltage, and when it is cold. [as a side note, the resistance of a coil actually rises as its temperature rises, causing less current to be drawn]
A solenoid does not behave in such a way as to draw the same number of watts, regardless of the voltage applied. In other words, if you took a perfectly good 12V PTO clutch and connected it to a 12V battery, it will draw a certain amount of current(likely to be in the 3-4 amp range based on a coil resistance in the 3-4 ohm range). If you take that exact same PTO clutch and connect it to a 6V source, it does NOT draw twice the current. In fact, it will draw half the current. The power is also halved. Why? Because the resistance of the coil remains the same in both cases. Ohm's law still applies. Current=Volts/Resistance
Specific to your problem, I'd suggest using your ohmmeter and checking the circuit(with battery disconnected of course). Disconnect clutch and check its resistance first. If the value you measure is significantly below the 3-4 ohm level, then it would appear your PTO is hosed. If it's good, then I'd work my way back looking for short of some kind to ground.
I submit this with the deepest respect for berts and his extensive experience! Not trying to start a flame war, rather I just want to give Ohm's Law its due!
Keep us posted!
I can be just as wrong as the next person so never worry about correcting me it is always appreciated.
History ( well western history to be precise ) only records a single person who was never wrong & he got crucified for that.
So with a big mouthful of humble pie , I will still put money on a foul fuse holder creating a very high resistance causing the fuse to blow.
It is nothing odd to find wires on mowers corroded a dozen or so places along their length due to water wicking up under the insulation.
For that reason I never like to rely on resistance readings cause one single strand of good wire in an otherwise corroded through cable will ohm up as being good, till you try to pass some current through it.
For the same reason the test lamp in the workshop is connected to a headlamp globe
#10
T
Telesis
T
Telesis
No worries Berts... I do the exact same thing when trying to track down an open circuit. For 12v stuff I use a headlamp also. When I work on home electrical (12vac rms mains here of course!) I use an incandescent bulb as a test load. In neither case do I use a digital volt meter alone. Too many times you can be deceived into thinking the circuit is just fine up to your test point only to find you have a marginal safety switch, seat switch, ignition switch etc. DVM says 12 volts but put a nice headlamp on it and the voltage across it drops dramatically because of the resistance of the bad switch!
FWIW....
FWIW....
#12
J
JeffNC
J
JeffNC
Good Lord I gotta say...this forum and participants are not only fantastic, but very impressive and generous. I want to thank each of you for taking your precious time to reply to my thread! I'm not at the expert level that you guys are so please overlook that of me. That said, I've done the following in addition to actions taken in my initial post:
1) Replaced Fuse Holder,
2) Replaced Battery Cables,
3) Replaced Battery (my fault, I broke a corroded terminal),
4) My second mower repair guy has not been able to fix this 20 amp fuse blowing issue:
1st Repairman: You need a new PTO Clutch, short in clutch, so purchased OEM Briggs and Stratton PTO Clutch for $250, same result.
2nd Repairman: All is well with blades cutting until about 10 minutes, then blows fuse. Told me that my PTO clutch was hot to the touch so was the cause of blowing 20 amp fuse. The real issue I see is...difficult to troulbleshoot since fuse does not blow or no issues at all, until afgter 10 minutes of cutting grass, then blades stop, and engine still runs,,,
I'm actually thinking that these 2 repairmen are 'shade tree' repairmen and do not know how to troubleshoot electrical grounds (ie troubleshooting like: if ignition switch is in one position, there is a short in 1 circuit or if ignition switch is in another position, its this circuit) and while I'm no expert either. I hate to consider the cost of a new mower when I feel as if there might be a simple fix.....everything is fantastic while the fuse does not blow...engine runs fantastic!! Thanks again you guys! Y'all so gracious and generous with your time on my behalf!! Thank you!!
1) Replaced Fuse Holder,
2) Replaced Battery Cables,
3) Replaced Battery (my fault, I broke a corroded terminal),
4) My second mower repair guy has not been able to fix this 20 amp fuse blowing issue:
1st Repairman: You need a new PTO Clutch, short in clutch, so purchased OEM Briggs and Stratton PTO Clutch for $250, same result.
2nd Repairman: All is well with blades cutting until about 10 minutes, then blows fuse. Told me that my PTO clutch was hot to the touch so was the cause of blowing 20 amp fuse. The real issue I see is...difficult to troulbleshoot since fuse does not blow or no issues at all, until afgter 10 minutes of cutting grass, then blades stop, and engine still runs,,,
I'm actually thinking that these 2 repairmen are 'shade tree' repairmen and do not know how to troubleshoot electrical grounds (ie troubleshooting like: if ignition switch is in one position, there is a short in 1 circuit or if ignition switch is in another position, its this circuit) and while I'm no expert either. I hate to consider the cost of a new mower when I feel as if there might be a simple fix.....everything is fantastic while the fuse does not blow...engine runs fantastic!! Thanks again you guys! Y'all so gracious and generous with your time on my behalf!! Thank you!!
#13
T
Telesis
T
Telesis
Jeff:
It sure seems like it is an intermittent short. This is one of those where you need to trace the positive 12 volt wire coming off the downstream side of the fuse and physically examine the wire for worn insulation, or evidence of it shorting to the chassis somewhere as Ilengine suggested. Keep in mind that anything or wire on the downstream side of the fuse can be causing the problem so you have to examine them all carefully. Focus on any point where a wire(s) is next to the frame or a bracket. It's highly unlikely that it's part of the coil inside the PTO. If it was, it is unlikely it would work again when you replaced the fuse.
Another "static" test is to turn it on, but don't start it. Turn on the PTO with a fresh fuse and see if it still blows after a few minutes without the vibration or movement from the engine running or mowing. I'm attaching a link to a nice troubleshooting guide for garden tractor clutches made by Warner Electric. Makes for great bathroom reading! More than you probably want to know about a PTO. FYI...
https://www.altraliterature.com/-/m...ner-electric/service-manuals/p-1097-6-we.ashx
Kelly
It sure seems like it is an intermittent short. This is one of those where you need to trace the positive 12 volt wire coming off the downstream side of the fuse and physically examine the wire for worn insulation, or evidence of it shorting to the chassis somewhere as Ilengine suggested. Keep in mind that anything or wire on the downstream side of the fuse can be causing the problem so you have to examine them all carefully. Focus on any point where a wire(s) is next to the frame or a bracket. It's highly unlikely that it's part of the coil inside the PTO. If it was, it is unlikely it would work again when you replaced the fuse.
Another "static" test is to turn it on, but don't start it. Turn on the PTO with a fresh fuse and see if it still blows after a few minutes without the vibration or movement from the engine running or mowing. I'm attaching a link to a nice troubleshooting guide for garden tractor clutches made by Warner Electric. Makes for great bathroom reading! More than you probably want to know about a PTO. FYI...
https://www.altraliterature.com/-/m...ner-electric/service-manuals/p-1097-6-we.ashx
Kelly
#14
J
JeffNC
J
JeffNC
The only thing I havent changed is the solenoid....could that be blowing the fuse? Thanks!
#15
T
Telesis
T
Telesis
Jeff, if you are referring to the starter solenoid, the answer is no. The only time power is applied to the solenoid coil is when the key switch is in the start position, not while it's in the run position.
Do you have a wiring diagram for the machine? Is there one online(I didn't see your model number anywhere in this thread)? Let us know the which model Simplicity you have. Can probably give better advice knowing the exact machine you have and locating a wiring diagram.
Do you have a wiring diagram for the machine? Is there one online(I didn't see your model number anywhere in this thread)? Let us know the which model Simplicity you have. Can probably give better advice knowing the exact machine you have and locating a wiring diagram.
#16
J
JeffNC
I really appreciate all that you guys are doing to assist me! Great website! The model number and description is:
2690574 - Simplicity Regent Lawn Tractor, 44" Deck, 20HP Kohler Hydro RMO. I've attached an electrical diagram to this post. Might there be a troubleshooting procedure that I could follow for this wiring diagram, as I performed your static test with a new fuse and the fuse never did blow after at least 15 minutes...sounds like an intermittent wiring short when mower is operating or moving (UGH)?......thanks very much!
J
JeffNC
Jeff, if you are referring to the starter solenoid, the answer is no. The only time power is applied to the solenoid coil is when the key switch is in the start position, not while it's in the run position.
Do you have a wiring diagram for the machine? Is there one online(I didn't see your model number anywhere in this thread)? Let us know the which model Simplicity you have. Can probably give better advice knowing the exact machine you have and locating a wiring diagram.
I really appreciate all that you guys are doing to assist me! Great website! The model number and description is:
2690574 - Simplicity Regent Lawn Tractor, 44" Deck, 20HP Kohler Hydro RMO. I've attached an electrical diagram to this post. Might there be a troubleshooting procedure that I could follow for this wiring diagram, as I performed your static test with a new fuse and the fuse never did blow after at least 15 minutes...sounds like an intermittent wiring short when mower is operating or moving (UGH)?......thanks very much!
Attachments
#17
B
bertsmobile1
B
bertsmobile1
That is a loom, not a wiring diagram .
Take the hood off and run the mower somewhere very dark
Look around the rectifier for sparking.
You can also disconnect the rectifier and see if the mower blows the fuse again.
With no power from the alternator you should get around 2 to 4 hours of mowing from a fully charged battery.
If the fuse does not blow with the alternator not connected then your problem is with the rectifier and the usual problem is a broken ground wire.
Take the hood off and run the mower somewhere very dark
Look around the rectifier for sparking.
You can also disconnect the rectifier and see if the mower blows the fuse again.
With no power from the alternator you should get around 2 to 4 hours of mowing from a fully charged battery.
If the fuse does not blow with the alternator not connected then your problem is with the rectifier and the usual problem is a broken ground wire.
#18
J
JeffNC
Going to try to see sparking around rectifier while running at dark. Thinking since rectifier is located inside and under the flywheel, sparking may be difficult to notice, so will also try disconnecting rectifier as you suggested to see if it cuts grass without blowing a fuse for 2-4 hours. If so, I'll remove blower/flywheel to inspect ground wire to rectifier and also possibly replace rectifier. These are great ideas and much appreciated! Will keep yall posted!! Thx so much!
J
JeffNC
That is a loom, not a wiring diagram .
Take the hood off and run the mower somewhere very dark
Look around the rectifier for sparking.
You can also disconnect the rectifier and see if the mower blows the fuse again.
With no power from the alternator you should get around 2 to 4 hours of mowing from a fully charged battery.
If the fuse does not blow with the alternator not connected then your problem is with the rectifier and the usual problem is a broken ground wire.
Going to try to see sparking around rectifier while running at dark. Thinking since rectifier is located inside and under the flywheel, sparking may be difficult to notice, so will also try disconnecting rectifier as you suggested to see if it cuts grass without blowing a fuse for 2-4 hours. If so, I'll remove blower/flywheel to inspect ground wire to rectifier and also possibly replace rectifier. These are great ideas and much appreciated! Will keep yall posted!! Thx so much!
#19
T
Telesis
T
Telesis
If you go to the Simplicity site, you can download the attached, which is the true wiring diagram you need for troubleshooting. It's at the bottom of the list of 11 results when you search their support site for the manual(s) for your unit. What you posted is a parts list page for the Electrical Group.
Refer to the Charging Circuit page and the PTO page. When the tractor is 'running' (as opposed to cranking or shutting off) the B, L, and A terminals of the ignition switch are connected together. [that's what the Ignition Switch table tells you at the top of the page] That means if you follow the wire from the 20A fuse, it goes to the B terminal. It connects to the L and A terminals from there. Note everywhere it goes, particularly that L goes to a tiepoint labeled "D" and several wires connect there.
What does all this mean? If ANY of those wires has an intermittent short to ground, the fuse will blow. That's because they are all connected together, and any one can be the culprit. Likely to be where a wire is near the metal frame and over time through vibration has worn away the insulation. For example, on the charging circuit page, the red/white wire could cause it. On the PTO page, it's not just the highlighted power wire to the PTO, but ANY wire that connects to point D.
Keep in mind, the diagram is the same on every page. They are just highlighting the specific circuits like Charging, Cranking, PTO, etc.
Take a look and see if this makes sense... Let us know what questions you might have.
Refer to the Charging Circuit page and the PTO page. When the tractor is 'running' (as opposed to cranking or shutting off) the B, L, and A terminals of the ignition switch are connected together. [that's what the Ignition Switch table tells you at the top of the page] That means if you follow the wire from the 20A fuse, it goes to the B terminal. It connects to the L and A terminals from there. Note everywhere it goes, particularly that L goes to a tiepoint labeled "D" and several wires connect there.
What does all this mean? If ANY of those wires has an intermittent short to ground, the fuse will blow. That's because they are all connected together, and any one can be the culprit. Likely to be where a wire is near the metal frame and over time through vibration has worn away the insulation. For example, on the charging circuit page, the red/white wire could cause it. On the PTO page, it's not just the highlighted power wire to the PTO, but ANY wire that connects to point D.
Keep in mind, the diagram is the same on every page. They are just highlighting the specific circuits like Charging, Cranking, PTO, etc.
Take a look and see if this makes sense... Let us know what questions you might have.
Attachments
#21
A
Auto Doc's
A
Auto Doc's
Verify the grounds (big and small) are all clean and tight starting with the battery cable and work from there. A cruddy, rusty ground or "green" corroded cable/wire creates high resistance. People always focus on the positive side and neglect the negative side of circuits.
While you are checking things, make sure the charging system is working properly, use a multi-meter. A weak or overcharging system will cause a PTO clutch to overheat and that will blow the fuse. A poorly grounded voltage regulator is also not uncommon.
While you are checking things, make sure the charging system is working properly, use a multi-meter. A weak or overcharging system will cause a PTO clutch to overheat and that will blow the fuse. A poorly grounded voltage regulator is also not uncommon.
#22
F
Freddie21
F
Freddie21
Could you not take a wire from the battery, put it through a 20a fuse, attach it to the clutch wire through a switch to see if the fuse blows after some time? This would confirm the condition of the clutch and it's lead. You could then cut the load side of the mower's fuse holder and attach your test wire there. Take it in steps to determine where the problem lies. You would need a schematic.
#23
Reverett
Reverett
Bert for President!There are 2 ways to approach a problem.
Toss parts at it till it goes away or find where the actual problem is and rectify it.
A solenoid draws POWER ( Watts ) and it does not care how it gets them
So 12V x 10A or 6 V x 20A or 3 V x 40A is all the same to it.
However Amps = heat.
Heat = RESISTANCE
RESISTANCE = VOLTAGE DROP
VOLTAGE DROP = more AMPS to make the same WATTS
And thus the self feeding loop continues till the fuse can't take it any more.
Much like the self feeding loop of face book morons makes bigger & more face book morons.
9 out of 10 mowers that come in here have disgusting battery connections and in particular the ground connection
Next is the actual fuse holder itself which is not waterproof because cheapskate owners & Face Book whingers will not pay the extra 50¢ to get waterproof connectors so the factories no longer fit them.
A proper search of this site will find around 2/3 of the blowing fuses problems were fixed by replacing the fuse holder.
Half of the remaining were fixed by cleaning or even replacing the battery cables & connections.
FWIW I do around 300 service / repairs a year and am yet to need to replace a clutch but I have gone through several 50 packs of fuse holders .
You are correct about their being a conspiracy out there.
It is called a free market lead economy
So whoever makes a mower with the lowest Hp to $ ratio or the lowest blade inch to $ ratio will outsell all others and prosper while the factories that make high quality mowers that sell for a fair & reasonable price will bob along being just barely profitable while the family that runs them continues to believe in the value of making quality over cost or go bankrupt.
That is the conspiracy, got nothing to do with badly designed PTO clutched except in the narrow minds of the technically if not totally ignorant who make 99% of cyber space.
The chances of you getting a dud PTO clutch if you bought it from a mower shop is about the same as winning the lottery
The chances of you getting a dud PTO clutch if you bought it from an on line Amazon or ebay vendor is about the same as it raining on any particular day.
All of the reject PTO clutches that are made in CHina end up being sold on line cheaply, usually because they are faulty .
#24
VRR.DYNDNS>BIZ
VRR.DYNDNS>BIZ
I was about to post similarly and thankful for this correct post. Now on to diagnosis. After checking that coil resistance, still with the fuse out and the coil disconnected, ( and the battery disconnected just for safety of the odd unknown), read the resistance of the balance of the tractors circuit resistance on the ignition switch side of the fuse under all switch settings. Record/report the lowest reading and under what condition. Lets assume a full 12.6 battery voltage is availalble and we blow a 20 amp fuse ( without the impact of connections as prior discussed), r=e/i = 12.6/20=6.3 ohms. Now some tractors have only one fuse, others have a separate fuse feeding only the PTO. that must be reviewed. If only one fuse and resistance is 7 ohms or less, continue to isolate where the resistance rises to a safe level. Besides wire shorts, the typical items are the clutch coil, the PTO switch, the ignition switch, the fuel solenoid, any fancy panels and reverse control panels, charging system diodes or regulator ( battery level will not be maintained ), and least likely are the interlock switches. When the ignition switch is on but no battery connection, the fuel solenoid resistance at play since in the run position it connects the solenoid to the battery feed given to the ignition switch. If at this point the resistance has hit the fuse blow threshold, disconnect the fuel solenoid and read the resistance. 99 out of 100 riders have no load under fuel disconnect status when the ignition switch is on so this resistance from fuse holder feeding to ignition switch to ground should be open circuit for 99 out of 100. Hope this helps.As an electrical engineer for over 40 years, I want to provide a bit of clarification to what berts said about solenoids. All a solenoid consists of electrically is simply a coil of wire. It creates a magnetic field when, in this case, a DC current passes through it. The amount of current it draws is determined by the resistance of the coil, which is typically under 5 ohms for a PTO. A solenoid does not draw watts per se. It draws a specific current based on its resistance and the voltage applied. When you multiply the voltage across the solenoid by the current through the solenoid, you will know the wattage or energy being used. A solenoid may specify a wattage in its spec sheet, but that is only when the unit is operated at its rated voltage, and when it is cold. [as a side note, the resistance of a coil actually rises as its temperature rises, causing less current to be drawn]
A solenoid does not behave in such a way as to draw the same number of watts, regardless of the voltage applied. In other words, if you took a perfectly good 12V PTO clutch and connected it to a 12V battery, it will draw a certain amount of current(likely to be in the 3-4 amp range based on a coil resistance in the 3-4 ohm range). If you take that exact same PTO clutch and connect it to a 6V source, it does NOT draw twice the current. In fact, it will draw half the current. The power is also halved. Why? Because the resistance of the coil remains the same in both cases. Ohm's law still applies. Current=Volts/Resistance
Specific to your problem, I'd suggest using your ohmmeter and checking the circuit(with battery disconnected of course). Disconnect clutch and check its resistance first. If the value you measure is significantly below the 3-4 ohm level, then it would appear your PTO is hosed. If it's good, then I'd work my way back looking for short of some kind to ground.
I submit this with the deepest respect for berts and his extensive experience! Not trying to start a flame war, rather I just want to give Ohm's Law its due!
Keep us posted!