Small generator over-voltage...

[Bob Engelhardt]

If there\'s a better site/forum for this question, please let me know.

I have an old (mid 80\'s) Sears Craftsman generator - 4 cycle B&S engine
& 120v, 1350W rated output. (Jeff - model 580.328172)

I haven\'t used it in decades so I cleaned it up & checked it out with
the intent to donate it to the Habitat ReStore.

Imagine my surprise when I measured the no-load output voltage at 134v
(with Fluke 36 True RMS meter). That dropped to 117v with a 10A load.

The no-load frequency is 62Hz, which is what the manual says it should
be (3720 RPM). That drops to 59Hz at 10A load.

The manual also claims a +-5% voltage regulation.

Seemingly unrelated, but ... the DC output is only 7v. Also, there is
1500Hz+-, 20v+- PP superimposed on the 120v 60hz output.

Note that I never before checked the voltage and I\'ve never had a
problem with it damaging loads (refrigerator, freezer, ??). So either
it\'s always been over-voltage & no-matter, or it\'s changed while sitting
idle.

Any ideas about what\'s going on here? And to diagnose & fix?

Thanks, Bob


The manual spec page:
https://imgur.com/phBAUpM
The circuit schematic:
https://imgur.com/vA6RIsa

 

[RheillyPhoull]

On 16/05/2020 11:07 pm, Bob Engelhardt wrote:

If there\'s a better site/forum for this question, please let me know.

I have an old (mid 80\'s) Sears Craftsman generator - 4 cycle B&S engine
& 120v, 1350W rated output.  (Jeff - model 580.328172)

I haven\'t used it in decades so I cleaned it up & checked it out with
the intent to donate it to the Habitat ReStore.

Imagine my surprise when I measured the no-load output voltage at 134v
(with Fluke 36 True RMS meter).  That dropped to 117v with a 10A load.

The no-load frequency is 62Hz, which is what the manual says it should
be (3720 RPM).  That drops to 59Hz at 10A load.

The manual also claims a +-5% voltage regulation.

Seemingly unrelated, but ... the DC output is only 7v.  Also, there is
1500Hz+-, 20v+- PP superimposed on the 120v 60hz output.

Note that I never before checked the voltage and I\'ve never had a
problem with it damaging loads (refrigerator, freezer, ??).  So either
it\'s always been over-voltage & no-matter, or it\'s changed while sitting
idle.

Any ideas about what\'s going on here?  And to diagnose & fix?

Thanks, Bob


The manual spec page:
https://imgur.com/phBAUpM
The circuit schematic:
https://imgur.com/vA6RIsa

Not familiar with USA products but a lot of the early ones were pretty
basic and that sounds like normal to me
So I don\'t think I\'d worry about tinkering with the control circuitry,
perhaps a quick check of any diodes or caps if any would be about it.

 

[RheillyPhoull]

On 16/05/2020 11:07 pm, Bob Engelhardt wrote:

If there\'s a better site/forum for this question, please let me know.

I have an old (mid 80\'s) Sears Craftsman generator - 4 cycle B&S engine
& 120v, 1350W rated output.  (Jeff - model 580.328172)

I haven\'t used it in decades so I cleaned it up & checked it out with
the intent to donate it to the Habitat ReStore.

Imagine my surprise when I measured the no-load output voltage at 134v
(with Fluke 36 True RMS meter).  That dropped to 117v with a 10A load.

The no-load frequency is 62Hz, which is what the manual says it should
be (3720 RPM).  That drops to 59Hz at 10A load.

The manual also claims a +-5% voltage regulation.

Seemingly unrelated, but ... the DC output is only 7v.  Also, there is
1500Hz+-, 20v+- PP superimposed on the 120v 60hz output.

Note that I never before checked the voltage and I\'ve never had a
problem with it damaging loads (refrigerator, freezer, ??).  So either
it\'s always been over-voltage & no-matter, or it\'s changed while sitting
idle.

Any ideas about what\'s going on here?  And to diagnose & fix?

Thanks, Bob


The manual spec page:
https://imgur.com/phBAUpM
The circuit schematic:
https://imgur.com/vA6RIsa

Not familiar with USA products but a lot of the early ones were pretty
basic and that sounds like normal to me
So I don\'t think I\'d worry about tinkering with the control circuitry,
perhaps a quick check of any diodes or caps if any would be about it.

 

[default]

On Sat, 16 May 2020 11:07:08 -0400, Bob Engelhardt
<BobEngelhardt@comcast.net> wrote:

If there\'s a better site/forum for this question, please let me know.

I have an old (mid 80\'s) Sears Craftsman generator - 4 cycle B&S engine
& 120v, 1350W rated output. (Jeff - model 580.328172)

I haven\'t used it in decades so I cleaned it up & checked it out with
the intent to donate it to the Habitat ReStore.

Imagine my surprise when I measured the no-load output voltage at 134v
(with Fluke 36 True RMS meter). That dropped to 117v with a 10A load.

The no-load frequency is 62Hz, which is what the manual says it should
be (3720 RPM). That drops to 59Hz at 10A load.

The manual also claims a +-5% voltage regulation.

Seemingly unrelated, but ... the DC output is only 7v. Also, there is
1500Hz+-, 20v+- PP superimposed on the 120v 60hz output.

Note that I never before checked the voltage and I\'ve never had a
problem with it damaging loads (refrigerator, freezer, ??). So either
it\'s always been over-voltage & no-matter, or it\'s changed while sitting
idle.

Any ideas about what\'s going on here? And to diagnose & fix?

Thanks, Bob


The manual spec page:
https://imgur.com/phBAUpM
The circuit schematic:
https://imgur.com/vA6RIsa

From the schematic... it appears as if the battery would be an
integral part of the alternator regulation, Do you have a good, fully
charged battery connected to the 12V terminals? That, diodes and
brushes are pretty much all that can go wrong.

If it has been sitting awhile, you may want to check that the brushes
move freely in the holders and the slip rings are free of corrosion.
The rings should be shiny and may be dark colored, that\'s normal but
you don\'t want any encrustations, green stuff, white flaky stuff,
etc.. If you sand them use very fine sandpaper, avoid Silicon Carbide
abrasives, and blow out the dust it creates.

 

[default]

On Sat, 16 May 2020 11:07:08 -0400, Bob Engelhardt
<BobEngelhardt@comcast.net> wrote:

If there\'s a better site/forum for this question, please let me know.

I have an old (mid 80\'s) Sears Craftsman generator - 4 cycle B&S engine
& 120v, 1350W rated output. (Jeff - model 580.328172)

I haven\'t used it in decades so I cleaned it up & checked it out with
the intent to donate it to the Habitat ReStore.

Imagine my surprise when I measured the no-load output voltage at 134v
(with Fluke 36 True RMS meter). That dropped to 117v with a 10A load.

The no-load frequency is 62Hz, which is what the manual says it should
be (3720 RPM). That drops to 59Hz at 10A load.

The manual also claims a +-5% voltage regulation.

Seemingly unrelated, but ... the DC output is only 7v. Also, there is
1500Hz+-, 20v+- PP superimposed on the 120v 60hz output.

Note that I never before checked the voltage and I\'ve never had a
problem with it damaging loads (refrigerator, freezer, ??). So either
it\'s always been over-voltage & no-matter, or it\'s changed while sitting
idle.

Any ideas about what\'s going on here? And to diagnose & fix?

Thanks, Bob


The manual spec page:
https://imgur.com/phBAUpM
The circuit schematic:
https://imgur.com/vA6RIsa

From the schematic... it appears as if the battery would be an
integral part of the alternator regulation, Do you have a good, fully
charged battery connected to the 12V terminals? That, diodes and
brushes are pretty much all that can go wrong.

If it has been sitting awhile, you may want to check that the brushes
move freely in the holders and the slip rings are free of corrosion.
The rings should be shiny and may be dark colored, that\'s normal but
you don\'t want any encrustations, green stuff, white flaky stuff,
etc.. If you sand them use very fine sandpaper, avoid Silicon Carbide
abrasives, and blow out the dust it creates.

 

[default]

On Sat, 16 May 2020 11:07:08 -0400, Bob Engelhardt
<BobEngelhardt@comcast.net> wrote:

If there\'s a better site/forum for this question, please let me know.

I have an old (mid 80\'s) Sears Craftsman generator - 4 cycle B&S engine
& 120v, 1350W rated output. (Jeff - model 580.328172)

I haven\'t used it in decades so I cleaned it up & checked it out with
the intent to donate it to the Habitat ReStore.

Imagine my surprise when I measured the no-load output voltage at 134v
(with Fluke 36 True RMS meter). That dropped to 117v with a 10A load.

The no-load frequency is 62Hz, which is what the manual says it should
be (3720 RPM). That drops to 59Hz at 10A load.

The manual also claims a +-5% voltage regulation.

Seemingly unrelated, but ... the DC output is only 7v. Also, there is
1500Hz+-, 20v+- PP superimposed on the 120v 60hz output.

Note that I never before checked the voltage and I\'ve never had a
problem with it damaging loads (refrigerator, freezer, ??). So either
it\'s always been over-voltage & no-matter, or it\'s changed while sitting
idle.

Any ideas about what\'s going on here? And to diagnose & fix?

Thanks, Bob


The manual spec page:
https://imgur.com/phBAUpM
The circuit schematic:
https://imgur.com/vA6RIsa

From the schematic... it appears as if the battery would be an
integral part of the alternator regulation, Do you have a good, fully
charged battery connected to the 12V terminals? That, diodes and
brushes are pretty much all that can go wrong.

If it has been sitting awhile, you may want to check that the brushes
move freely in the holders and the slip rings are free of corrosion.
The rings should be shiny and may be dark colored, that\'s normal but
you don\'t want any encrustations, green stuff, white flaky stuff,
etc.. If you sand them use very fine sandpaper, avoid Silicon Carbide
abrasives, and blow out the dust it creates.

 

[Michael Terrell]

On Monday, May 18, 2020 at 4:12:49 AM UTC-4, default wrote:

On Sat, 16 May 2020 11:07:08 -0400, Bob Engelhardt wrote:

If there\'s a better site/forum for this question, please let me know.

I have an old (mid 80\'s) Sears Craftsman generator - 4 cycle B&S engine
& 120v, 1350W rated output. (Jeff - model 580.328172)

I haven\'t used it in decades so I cleaned it up & checked it out with
the intent to donate it to the Habitat ReStore.

Imagine my surprise when I measured the no-load output voltage at 134v
(with Fluke 36 True RMS meter). That dropped to 117v with a 10A load.

The no-load frequency is 62Hz, which is what the manual says it should
be (3720 RPM). That drops to 59Hz at 10A load.

The manual also claims a +-5% voltage regulation.

Seemingly unrelated, but ... the DC output is only 7v. Also, there is
1500Hz+-, 20v+- PP superimposed on the 120v 60hz output.

Note that I never before checked the voltage and I\'ve never had a
problem with it damaging loads (refrigerator, freezer, ??). So either
it\'s always been over-voltage & no-matter, or it\'s changed while sitting
idle.

Any ideas about what\'s going on here? And to diagnose & fix?

Thanks, Bob


The manual spec page:
https://imgur.com/phBAUpM
The circuit schematic:
https://imgur.com/vA6RIsa

From the schematic... it appears as if the battery would be an
integral part of the alternator regulation, Do you have a good, fully
charged battery connected to the 12V terminals? That, diodes and
brushes are pretty much all that can go wrong.

If it has been sitting awhile, you may want to check that the brushes
move freely in the holders and the slip rings are free of corrosion.
The rings should be shiny and may be dark colored, that\'s normal but
you don\'t want any encrustations, green stuff, white flaky stuff,
etc.. If you sand them use very fine sandpaper, avoid Silicon Carbide
abrasives, and blow out the dust it creates.

Metal polish (EG: Brasso), or a large in eraser is better than sandpaper. It leaves a highly polished surface that only removes the oxides.

Small generators are intended for lighting, or power tools where you only have to be close. Also, without a load the output isn\'t a clean sine wave. Any inductive load helps to clean up their output.

 

[Michael Terrell]

On Monday, May 18, 2020 at 4:12:49 AM UTC-4, default wrote:

On Sat, 16 May 2020 11:07:08 -0400, Bob Engelhardt wrote:

If there\'s a better site/forum for this question, please let me know.

I have an old (mid 80\'s) Sears Craftsman generator - 4 cycle B&S engine
& 120v, 1350W rated output. (Jeff - model 580.328172)

I haven\'t used it in decades so I cleaned it up & checked it out with
the intent to donate it to the Habitat ReStore.

Imagine my surprise when I measured the no-load output voltage at 134v
(with Fluke 36 True RMS meter). That dropped to 117v with a 10A load.

The no-load frequency is 62Hz, which is what the manual says it should
be (3720 RPM). That drops to 59Hz at 10A load.

The manual also claims a +-5% voltage regulation.

Seemingly unrelated, but ... the DC output is only 7v. Also, there is
1500Hz+-, 20v+- PP superimposed on the 120v 60hz output.

Note that I never before checked the voltage and I\'ve never had a
problem with it damaging loads (refrigerator, freezer, ??). So either
it\'s always been over-voltage & no-matter, or it\'s changed while sitting
idle.

Any ideas about what\'s going on here? And to diagnose & fix?

Thanks, Bob


The manual spec page:
https://imgur.com/phBAUpM
The circuit schematic:
https://imgur.com/vA6RIsa

From the schematic... it appears as if the battery would be an
integral part of the alternator regulation, Do you have a good, fully
charged battery connected to the 12V terminals? That, diodes and
brushes are pretty much all that can go wrong.

If it has been sitting awhile, you may want to check that the brushes
move freely in the holders and the slip rings are free of corrosion.
The rings should be shiny and may be dark colored, that\'s normal but
you don\'t want any encrustations, green stuff, white flaky stuff,
etc.. If you sand them use very fine sandpaper, avoid Silicon Carbide
abrasives, and blow out the dust it creates.

Metal polish (EG: Brasso), or a large in eraser is better than sandpaper. It leaves a highly polished surface that only removes the oxides.

Small generators are intended for lighting, or power tools where you only have to be close. Also, without a load the output isn\'t a clean sine wave. Any inductive load helps to clean up their output.

 

[Ralph Mowery]

In article <f4d3ad1d-db6c-45a2-9b32-18571ebe8995@googlegroups.com>,
terrell.michael.a@gmail.com says...

Small generators are intended for lighting, or power tools where you only have to be close. Also, without a load the output isn\'t a clean sine wave. Any inductive load helps to clean up their output.

I noticed on a 5 KW generator I have that the generator engine would
tend to hunt around for speed unless I had a load of around 500 or more
watts connected to it. Then it smoothed out some and got better with a 1
kw load. Using fresh gas without the ethanol in it seemed to help some
too.

This is a generator about 20 years old, but does not have very many
hours on it. I don\'t worry about the waveform. It does not have any
voltage regulator circuit in it and just relies on the governor of the
engine to hold it constnt.

There used to be a big thing about the generators not suited for
electronics in hte past. I don\'t buy that for the general home
electronics unless maybe some high end sterio equipment. The computer
supplies are designed for wide ranges of power and the digital TV sets
do not depend on the frequency being 60 HZ. Most electronics for the
home now use switching power supplies and those things generate very
dirty power theirsleves.

 

[Michael Terrell]

On Monday, May 18, 2020 at 4:12:49 AM UTC-4, default wrote:

On Sat, 16 May 2020 11:07:08 -0400, Bob Engelhardt wrote:

If there\'s a better site/forum for this question, please let me know.

I have an old (mid 80\'s) Sears Craftsman generator - 4 cycle B&S engine
& 120v, 1350W rated output. (Jeff - model 580.328172)

I haven\'t used it in decades so I cleaned it up & checked it out with
the intent to donate it to the Habitat ReStore.

Imagine my surprise when I measured the no-load output voltage at 134v
(with Fluke 36 True RMS meter). That dropped to 117v with a 10A load.

The no-load frequency is 62Hz, which is what the manual says it should
be (3720 RPM). That drops to 59Hz at 10A load.

The manual also claims a +-5% voltage regulation.

Seemingly unrelated, but ... the DC output is only 7v. Also, there is
1500Hz+-, 20v+- PP superimposed on the 120v 60hz output.

Note that I never before checked the voltage and I\'ve never had a
problem with it damaging loads (refrigerator, freezer, ??). So either
it\'s always been over-voltage & no-matter, or it\'s changed while sitting
idle.

Any ideas about what\'s going on here? And to diagnose & fix?

Thanks, Bob


The manual spec page:
https://imgur.com/phBAUpM
The circuit schematic:
https://imgur.com/vA6RIsa

From the schematic... it appears as if the battery would be an
integral part of the alternator regulation, Do you have a good, fully
charged battery connected to the 12V terminals? That, diodes and
brushes are pretty much all that can go wrong.

If it has been sitting awhile, you may want to check that the brushes
move freely in the holders and the slip rings are free of corrosion.
The rings should be shiny and may be dark colored, that\'s normal but
you don\'t want any encrustations, green stuff, white flaky stuff,
etc.. If you sand them use very fine sandpaper, avoid Silicon Carbide
abrasives, and blow out the dust it creates.

Metal polish (EG: Brasso), or a large in eraser is better than sandpaper. It leaves a highly polished surface that only removes the oxides.

Small generators are intended for lighting, or power tools where you only have to be close. Also, without a load the output isn\'t a clean sine wave. Any inductive load helps to clean up their output.

 

[Ralph Mowery]

In article <f4d3ad1d-db6c-45a2-9b32-18571ebe8995@googlegroups.com>,
terrell.michael.a@gmail.com says...

Small generators are intended for lighting, or power tools where you only have to be close. Also, without a load the output isn\'t a clean sine wave. Any inductive load helps to clean up their output.

I noticed on a 5 KW generator I have that the generator engine would
tend to hunt around for speed unless I had a load of around 500 or more
watts connected to it. Then it smoothed out some and got better with a 1
kw load. Using fresh gas without the ethanol in it seemed to help some
too.

This is a generator about 20 years old, but does not have very many
hours on it. I don\'t worry about the waveform. It does not have any
voltage regulator circuit in it and just relies on the governor of the
engine to hold it constnt.

There used to be a big thing about the generators not suited for
electronics in hte past. I don\'t buy that for the general home
electronics unless maybe some high end sterio equipment. The computer
supplies are designed for wide ranges of power and the digital TV sets
do not depend on the frequency being 60 HZ. Most electronics for the
home now use switching power supplies and those things generate very
dirty power theirsleves.

 

[George Herold]

On Saturday, May 16, 2020 at 11:07:29 AM UTC-4, Bob Engelhardt wrote:

If there\'s a better site/forum for this question, please let me know.

I have an old (mid 80\'s) Sears Craftsman generator - 4 cycle B&S engine
& 120v, 1350W rated output. (Jeff - model 580.328172)

I haven\'t used it in decades so I cleaned it up & checked it out with
the intent to donate it to the Habitat ReStore.

Imagine my surprise when I measured the no-load output voltage at 134v
(with Fluke 36 True RMS meter). That dropped to 117v with a 10A load.

The no-load frequency is 62Hz, which is what the manual says it should
be (3720 RPM). That drops to 59Hz at 10A load.

The manual also claims a +-5% voltage regulation.

Seemingly unrelated, but ... the DC output is only 7v. Also, there is
1500Hz+-, 20v+- PP superimposed on the 120v 60hz output.

Note that I never before checked the voltage and I\'ve never had a
problem with it damaging loads (refrigerator, freezer, ??). So either
it\'s always been over-voltage & no-matter, or it\'s changed while sitting
idle.

Any ideas about what\'s going on here? And to diagnose & fix?

Thanks, Bob

Those numbers seem fine to me. What\'s the voltage with a 100W
incandescent as load? (Or even a 10-20W resistor?)

George H.
who gave his old Sears gen. to his brother when he got a new one
with a much bigger muffler!

The manual spec page:
https://imgur.com/phBAUpM
The circuit schematic:
https://imgur.com/vA6RIsa

 

[George Herold]

On Saturday, May 16, 2020 at 11:07:29 AM UTC-4, Bob Engelhardt wrote:

If there\'s a better site/forum for this question, please let me know.

I have an old (mid 80\'s) Sears Craftsman generator - 4 cycle B&S engine
& 120v, 1350W rated output. (Jeff - model 580.328172)

I haven\'t used it in decades so I cleaned it up & checked it out with
the intent to donate it to the Habitat ReStore.

Imagine my surprise when I measured the no-load output voltage at 134v
(with Fluke 36 True RMS meter). That dropped to 117v with a 10A load.

The no-load frequency is 62Hz, which is what the manual says it should
be (3720 RPM). That drops to 59Hz at 10A load.

The manual also claims a +-5% voltage regulation.

Seemingly unrelated, but ... the DC output is only 7v. Also, there is
1500Hz+-, 20v+- PP superimposed on the 120v 60hz output.

Note that I never before checked the voltage and I\'ve never had a
problem with it damaging loads (refrigerator, freezer, ??). So either
it\'s always been over-voltage & no-matter, or it\'s changed while sitting
idle.

Any ideas about what\'s going on here? And to diagnose & fix?

Thanks, Bob

Those numbers seem fine to me. What\'s the voltage with a 100W
incandescent as load? (Or even a 10-20W resistor?)

George H.
who gave his old Sears gen. to his brother when he got a new one
with a much bigger muffler!

The manual spec page:
https://imgur.com/phBAUpM
The circuit schematic:
https://imgur.com/vA6RIsa

 

[default]

On Mon, 18 May 2020 05:02:35 -0700 (PDT), Michael Terrell
<terrell.michael.a@gmail.com> wrote:

On Monday, May 18, 2020 at 4:12:49 AM UTC-4, default wrote:
On Sat, 16 May 2020 11:07:08 -0400, Bob Engelhardt wrote:

If there\'s a better site/forum for this question, please let me know.

I have an old (mid 80\'s) Sears Craftsman generator - 4 cycle B&S engine
& 120v, 1350W rated output. (Jeff - model 580.328172)

I haven\'t used it in decades so I cleaned it up & checked it out with
the intent to donate it to the Habitat ReStore.

Imagine my surprise when I measured the no-load output voltage at 134v
(with Fluke 36 True RMS meter). That dropped to 117v with a 10A load.

The no-load frequency is 62Hz, which is what the manual says it should
be (3720 RPM). That drops to 59Hz at 10A load.

The manual also claims a +-5% voltage regulation.

Seemingly unrelated, but ... the DC output is only 7v. Also, there is
1500Hz+-, 20v+- PP superimposed on the 120v 60hz output.

Note that I never before checked the voltage and I\'ve never had a
problem with it damaging loads (refrigerator, freezer, ??). So either
it\'s always been over-voltage & no-matter, or it\'s changed while sitting
idle.

Any ideas about what\'s going on here? And to diagnose & fix?

Thanks, Bob


The manual spec page:
https://imgur.com/phBAUpM
The circuit schematic:
https://imgur.com/vA6RIsa

From the schematic... it appears as if the battery would be an
integral part of the alternator regulation, Do you have a good, fully
charged battery connected to the 12V terminals? That, diodes and
brushes are pretty much all that can go wrong.

If it has been sitting awhile, you may want to check that the brushes
move freely in the holders and the slip rings are free of corrosion.
The rings should be shiny and may be dark colored, that\'s normal but
you don\'t want any encrustations, green stuff, white flaky stuff,
etc.. If you sand them use very fine sandpaper, avoid Silicon Carbide
abrasives, and blow out the dust it creates.

Metal polish (EG: Brasso), or a large in eraser is better than sandpaper. It leaves a highly polished surface that only removes the oxides.

Small generators are intended for lighting, or power tools where you only have to be close. Also, without a load the output isn\'t a clean sine wave. Any inductive load helps to clean up their output.

Those old-school ink erasers were the best IMO. Don\'t see them
anymore...

Fine abrasives have the advantage of cleaning off the brush surfaces
and reseating brushes, so it may be more advantageous in a generator
that has been in storage for awhile. Otherwise I concur, a pencil
eraser is a good choice.

 

[default]

On Mon, 18 May 2020 05:02:35 -0700 (PDT), Michael Terrell
<terrell.michael.a@gmail.com> wrote:

On Monday, May 18, 2020 at 4:12:49 AM UTC-4, default wrote:
On Sat, 16 May 2020 11:07:08 -0400, Bob Engelhardt wrote:

If there\'s a better site/forum for this question, please let me know.

I have an old (mid 80\'s) Sears Craftsman generator - 4 cycle B&S engine
& 120v, 1350W rated output. (Jeff - model 580.328172)

I haven\'t used it in decades so I cleaned it up & checked it out with
the intent to donate it to the Habitat ReStore.

Imagine my surprise when I measured the no-load output voltage at 134v
(with Fluke 36 True RMS meter). That dropped to 117v with a 10A load.

The no-load frequency is 62Hz, which is what the manual says it should
be (3720 RPM). That drops to 59Hz at 10A load.

The manual also claims a +-5% voltage regulation.

Seemingly unrelated, but ... the DC output is only 7v. Also, there is
1500Hz+-, 20v+- PP superimposed on the 120v 60hz output.

Note that I never before checked the voltage and I\'ve never had a
problem with it damaging loads (refrigerator, freezer, ??). So either
it\'s always been over-voltage & no-matter, or it\'s changed while sitting
idle.

Any ideas about what\'s going on here? And to diagnose & fix?

Thanks, Bob


The manual spec page:
https://imgur.com/phBAUpM
The circuit schematic:
https://imgur.com/vA6RIsa

From the schematic... it appears as if the battery would be an
integral part of the alternator regulation, Do you have a good, fully
charged battery connected to the 12V terminals? That, diodes and
brushes are pretty much all that can go wrong.

If it has been sitting awhile, you may want to check that the brushes
move freely in the holders and the slip rings are free of corrosion.
The rings should be shiny and may be dark colored, that\'s normal but
you don\'t want any encrustations, green stuff, white flaky stuff,
etc.. If you sand them use very fine sandpaper, avoid Silicon Carbide
abrasives, and blow out the dust it creates.

Metal polish (EG: Brasso), or a large in eraser is better than sandpaper. It leaves a highly polished surface that only removes the oxides.

Small generators are intended for lighting, or power tools where you only have to be close. Also, without a load the output isn\'t a clean sine wave. Any inductive load helps to clean up their output.

Those old-school ink erasers were the best IMO. Don\'t see them
anymore...

Fine abrasives have the advantage of cleaning off the brush surfaces
and reseating brushes, so it may be more advantageous in a generator
that has been in storage for awhile. Otherwise I concur, a pencil
eraser is a good choice.

 

[Michael Terrell]

On Monday, May 18, 2020 at 6:43:19 PM UTC-4, default wrote:

On Mon, 18 May 2020 05:02:35 -0700 (PDT), Michael Terrell wrote:

Metal polish (EG: Brasso), or a large in eraser is better than sandpaper.. It leaves a highly polished surface that only removes the oxides.

Small generators are intended for lighting, or power tools where you only have to be close. Also, without a load the output isn\'t a clean sine wave.. Any inductive load helps to clean up their output.

Those old-school ink erasers were the best IMO. Don\'t see them
anymore...

Fine abrasives have the advantage of cleaning off the brush surfaces
and reseating brushes, so it may be more advantageous in a generator
that has been in storage for awhile. Otherwise I concur, a pencil
eraser is a good choice.

I used to rebuild vacuum clean motors as a sideline. The customer kept asking to see my armature lathe, since they commutators all looked brand new.. These were made by Lamb, and 120VAC. I would connect them to my 24V DC power supply and polish the commutator with the motor running at a reduced speed. He gave me all his bad motors. I sold them back to him at half the wholesale price, with over a 50% recover rate. Many didn\'t run because the commutator was so nasty. I reground a blade for my Exacto knife to undercut the mica spacers. A lot of the time it only took five minutes to revive a motor. He never did figure it out, but he never brought back any of my repaired motors. Other had bad bearings or burnt windings so they were stripped and the good parts were used to make a good fan. I ended up with scrap aluminum and copper from the scrap parts, as well.

Ink erasers are still available, but you might have to go o an office supply store or buy them online.

 

[Michael Terrell]

On Monday, May 18, 2020 at 6:43:19 PM UTC-4, default wrote:

On Mon, 18 May 2020 05:02:35 -0700 (PDT), Michael Terrell wrote:

Metal polish (EG: Brasso), or a large in eraser is better than sandpaper.. It leaves a highly polished surface that only removes the oxides.

Small generators are intended for lighting, or power tools where you only have to be close. Also, without a load the output isn\'t a clean sine wave.. Any inductive load helps to clean up their output.

Those old-school ink erasers were the best IMO. Don\'t see them
anymore...

Fine abrasives have the advantage of cleaning off the brush surfaces
and reseating brushes, so it may be more advantageous in a generator
that has been in storage for awhile. Otherwise I concur, a pencil
eraser is a good choice.

I used to rebuild vacuum clean motors as a sideline. The customer kept asking to see my armature lathe, since they commutators all looked brand new.. These were made by Lamb, and 120VAC. I would connect them to my 24V DC power supply and polish the commutator with the motor running at a reduced speed. He gave me all his bad motors. I sold them back to him at half the wholesale price, with over a 50% recover rate. Many didn\'t run because the commutator was so nasty. I reground a blade for my Exacto knife to undercut the mica spacers. A lot of the time it only took five minutes to revive a motor. He never did figure it out, but he never brought back any of my repaired motors. Other had bad bearings or burnt windings so they were stripped and the good parts were used to make a good fan. I ended up with scrap aluminum and copper from the scrap parts, as well.

Ink erasers are still available, but you might have to go o an office supply store or buy them online.

 

[default]

On Mon, 18 May 2020 23:36:52 -0700 (PDT), Michael Terrell
<terrell.michael.a@gmail.com> wrote:

On Monday, May 18, 2020 at 6:43:19 PM UTC-4, default wrote:

On Mon, 18 May 2020 05:02:35 -0700 (PDT), Michael Terrell wrote:

Metal polish (EG: Brasso), or a large in eraser is better than sandpaper. It leaves a highly polished surface that only removes the oxides.

Small generators are intended for lighting, or power tools where you only have to be close. Also, without a load the output isn\'t a clean sine wave. Any inductive load helps to clean up their output.

Those old-school ink erasers were the best IMO. Don\'t see them
anymore...

Fine abrasives have the advantage of cleaning off the brush surfaces
and reseating brushes, so it may be more advantageous in a generator
that has been in storage for awhile. Otherwise I concur, a pencil
eraser is a good choice.


I used to rebuild vacuum clean motors as a sideline. The customer kept asking to see my armature lathe, since they commutators all looked brand new. These were made by Lamb, and 120VAC. I would connect them to my 24V DC power supply and polish the commutator with the motor running at a reduced speed. He gave me all his bad motors. I sold them back to him at half the wholesale price, with over a 50% recover rate. Many didn\'t run because the commutator was so nasty. I reground a blade for my Exacto knife to undercut the mica spacers. A lot of the time it only took five minutes to revive a motor. He never did figure it out, but he never brought back any of my repaired motors. Other had bad bearings or burnt windings so they were stripped and the good parts were used to make a good fan. I ended up with scrap aluminum and copper from the scrap parts, as well.

Ink erasers are still available, but you might have to go o an office supply store or buy them online.

Way back, I worked a part time job repairing consumer and commercial
electronics while going to school. One of the sidelines of the
business was installing custom stereos in vehicles. For that there
were high school kids with a mechanical bent that would do all the
work. None of them could afford decent cars themselves so there were
a fleet of high-mileage junkers parked outside the building.

There was also this place \"Ben\'s Armature,\" who\'d built a reputation
for repairing car alternators. Everyone in town swore by them being
the best, but they\'d always diagnose a bad field winding (which they
called the armature) and the cure was always to \"rewind the armature.\"
at a cost of $50-150. This old Land Cruiser I used to haul my boat
around succumbed one day and I went there and listened to the
estimate.

I decided to rewind it myself and save a buck. How hard could it be?
I took it apart and there was nothing left of the brushes. $4 for a
set of brushes (with springs and holder) and it could have been fixed
without even taking the alternator off the truck.

One by one the junkers the high schoolers used also went to Ben\'s.
(120-200K/Mi the brushes fail) In no time the business had another
sideline. We\'d charge $20 labor and $4-15 for brushes (seldom had to
do more than remove a few screws and replace the brushes)

I did get to \"rewind the armature\" one day on an old 750 Honda
motorcycle. The only hard part of doing it was in fabricating a
bobbin to hold the wire \'till the epoxy set - they used a \"self
supporting coil\" in the original alternator.

 

[Michael Terrell]

On Tuesday, May 19, 2020 at 5:24:04 AM UTC-4, default wrote:

On Mon, 18 May 2020 23:36:52 -0700 (PDT), Michael Terrell wrote:

On Monday, May 18, 2020 at 6:43:19 PM UTC-4, default wrote:

On Mon, 18 May 2020 05:02:35 -0700 (PDT), Michael Terrell wrote:

Metal polish (EG: Brasso), or a large in eraser is better than sandpaper. It leaves a highly polished surface that only removes the oxides.

Small generators are intended for lighting, or power tools where you only have to be close. Also, without a load the output isn\'t a clean sine wave. Any inductive load helps to clean up their output.

Those old-school ink erasers were the best IMO. Don\'t see them
anymore...

Fine abrasives have the advantage of cleaning off the brush surfaces
and reseating brushes, so it may be more advantageous in a generator
that has been in storage for awhile. Otherwise I concur, a pencil
eraser is a good choice.


I used to rebuild vacuum clean motors as a sideline. The customer kept asking to see my armature lathe, since they commutators all looked brand new. These were made by Lamb, and 120VAC. I would connect them to my 24V DC power supply and polish the commutator with the motor running at a reduced speed. He gave me all his bad motors. I sold them back to him at half the wholesale price, with over a 50% recover rate. Many didn\'t run because the commutator was so nasty. I reground a blade for my Exacto knife to undercut the mica spacers. A lot of the time it only took five minutes to revive a motor. He never did figure it out, but he never brought back any of my repaired motors. Other had bad bearings or burnt windings so they were stripped and the good parts were used to make a good fan. I ended up with scrap aluminum and copper from the scrap parts, as well.

Ink erasers are still available, but you might have to go o an office supply store or buy them online.

Way back, I worked a part time job repairing consumer and commercial
electronics while going to school. One of the sidelines of the
business was installing custom stereos in vehicles. For that there
were high school kids with a mechanical bent that would do all the
work. None of them could afford decent cars themselves so there were
a fleet of high-mileage junkers parked outside the building.

There was also this place \"Ben\'s Armature,\" who\'d built a reputation
for repairing car alternators. Everyone in town swore by them being
the best, but they\'d always diagnose a bad field winding (which they
called the armature) and the cure was always to \"rewind the armature.\"
at a cost of $50-150. This old Land Cruiser I used to haul my boat
around succumbed one day and I went there and listened to the
estimate.

I decided to rewind it myself and save a buck. How hard could it be?
I took it apart and there was nothing left of the brushes. $4 for a
set of brushes (with springs and holder) and it could have been fixed
without even taking the alternator off the truck.

One by one the junkers the high schoolers used also went to Ben\'s.
(120-200K/Mi the brushes fail) In no time the business had another
sideline. We\'d charge $20 labor and $4-15 for brushes (seldom had to
do more than remove a few screws and replace the brushes)

I did get to \"rewind the armature\" one day on an old 750 Honda
motorcycle. The only hard part of doing it was in fabricating a
bobbin to hold the wire \'till the epoxy set - they used a \"self
supporting coil\" in the original alternator.

I\'ve replaced a lot of brushes in Alternators and Starters. I had to junk one Alternator because a weld was broken where a wire was attached to a slip ring. Solder wouldn\'t hold and I couldn\'t get it welded. I bought another alternator at a junkyard for $20. The owner read the GM markings and said it was a low current model. He as wrong.it was the highest current version.

I installed and repaired car radios right after I graduated. My first car was a \'63 Pontiac Catalina convertable. It was seven yeas old, but some people thought anything over two years old was junk.

 

[Bob Engelhardt]

On 5/16/2020 11:07 AM, Bob Engelhardt wrote:

...
Imagine my surprise when I measured the no-load output voltage at 134v
(with Fluke 36 True RMS meter).
...

My Fluke lies!! I put a scope on the generator & got 210v p-p (or 150v
p-p depending upon what the peak is with the superimposed 1500Hz),
that\'s 71v (or 50v)RMS ... assuming sine wave, which it is, kind of.

https://imgur.com/AQlOpmA (2ms & 50v per)

I had it on the scope before, but I must have been in a fog to misread
it so badly, or I didn\'t read the p-p at all, IDR.

So I was 180* out of phase with the problem: it\'s way, way under voltage
instead of way over voltage. Which is easier to understand possible
causes - basically there\'s too little excitation current. I couldn\'t
understand how it could possibly be over voltage/too much excitation
current.

The diodes check OK with a DMM, so I\'ll look at the slip rings. Or for
a poor connection.

Thanks for the replies.