YM155D charging reliability

[astromarmot-HT]

Good day,
I have a YM155D that will not charge. I tested the two leads and the low/red side isn't putting out any voltage and the high/yellow/red wire puts out somewhere less than 12 volts when at top RPM if it's grounded back to the case. I see Hoye sells a replacement generator, but a mechanic I know told me that the old "magneto" chargers were just asking for trouble even I put a new/rebuilt one on.

I was just curious what peoples' experiences has been with this over the long haul. I plan on keeping this tractor for many years so I don't mind the investment if it's a reliable charging system, but I don't want to throw good money after bad if there's a way to put a more reliable alternator of comparable size in its place.

Thanks in advance for any replies.

 

[winston-HT]

These dynamo's put out ac voltage. Is that what you were checking? At 1500 to 2000 rpm you should get 18 or so ac volts.

Have your read all the notes connected here? http://www.hoyetractor.com/BASK.htm

 

[astromarmot-HT]

This model has the diodes on the generator, and according to the service manual ought to be putting out 28VDC when tested between the +(red) lead and the generator body...

 

[winston-HT]

You have the manual and sounds like your test proves the dynamo bad. Have you spoken with Hoye about the dynamo options available? If this is the first problem in 30 years a new one might be in order. I can tell you from experiance you might have a tough time fitting an alternator in your available space. Are the bearings tight in yours?

 

[Aaron-HT]

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I disagree. In fact our experience is the exact opposite. They are extremely reliable. An alternator/dynamo failing after 35+ years of use is hardly 'trouble'.

Your options for upgrading the charging system on that tractor are <U><s></s>extremely<e></e></U> limited due to 1)- space and 2)- the fact that the dynamo is what supports the fan. You would have to come up with some way to support the fan as well as rig up a mount to hang the alternator out of the side (or top) of the hood.

I would either experiment with replacing the diodes in the alternator or just replace it.

 

[astromarmot-HT]

Thank you for the reply. I've only owned the tractor for about a month, so I don't know how often or if the generator had problems in the past. The fellow I bought it from didn't mention it wasn't charging, but left me to discover it on my own. This is my first rodeo with this type of charging system so I was curious.

How difficult is it to acquire the diodes? I tried to have a local alternator shop(the place brags they've been in business for over 40 years) look at it, and the guy looked at me like I had three heads.

 

[Aaron-HT]

I don't know what it uses for diodes (should be printed on them?) but our local radio shack has a pretty good selection.

 

[alan-HT]

There are so many 155s and the alternators are so long-lasting and easy to remove and ship that another option is to order a used one from a salvage yard.

 

[SDgray-HT]

the "magneto type"charging system is very reliable-used for decades on most motorcycles and small engines,those usually putting out AC current to a rectifier regulator.If your stator coils are still good,you can disconnect the diodes,solder on a couple wires to stator coil for AC output to an AC input rectifier regulator and go <E></E> When I had the dymamo apart on my late-'75 built 1500,discovered the stator coils were loose so I had to tighten those up.(can give details on that 1500 dynamo repair if anyone interested)