Repair my Emglo AM78-HV4V air compressor
 

We were using our Emglo and shut it down for a lunch break. When we came
back and tried to start it again all we got was a load electrical hum and
sometimes it would pop our 15 amp breaker.

I pulled the compressor/electric motor unit loose from the rest of the
compressor so I could get to its guts. When I turned the fan blade by hand
(it turned very easily) I could hear the compressor piston working. I even
connected the AC power back up but still heard the hum. When I gave the fan
a twist the motor started running the compressor. However, the motor won't
start the compressor on its own.

I tried a quick test of the start-up capacitor with my multimeter and it
appears to be OK. It slowly climbs in ohms until infinity. Reversed the
probes and it does the same thing. Sounds like the capacitor is OK to me.

I wanted to pull the electric motor loose from the case so I could see the
brushes and rotor. I removed all the mounting screws from everything I
could see, but I can't seem to pull the unit apart to get to the motor.
Everything is loose and I can twist the case a few degrees, but I can't pull
it apart.

Anybody know how I can get the motor out so I can look at its guts. Any
help is appreciated. Pretend I'm a dunce and be pretty specific.

Thanks,
Mike

Repair my Emglo AM78-HV4V air compressor
 

Just because a cap doesn't leak at the low voltage provided by a VOM
does not mean it isn't leaking at working voltage. Try substituting
another cap and see if it helps. My outside air conditioning unit was
doing exactly the same thing. Diagnosis: bad starting cap. If your
motor uses two caps (one for start, one for run) check the centrufugal
switch
that controls the caps to see if it is broken.
Good luck. 73 Gary

Repair my Emglo AM78-HV4V air compressor
 

Mike S. wrote:

We were using our Emglo and shut it down for a lunch break. When we came
back and tried to start it again all we got was a load electrical hum and
sometimes it would pop our 15 amp breaker.

I pulled the compressor/electric motor unit loose from the rest of the
compressor so I could get to its guts. When I turned the fan blade by hand
(it turned very easily) I could hear the compressor piston working. I even
connected the AC power back up but still heard the hum. When I gave the fan
a twist the motor started running the compressor. However, the motor won't
start the compressor on its own.

I tried a quick test of the start-up capacitor with my multimeter and it
appears to be OK. It slowly climbs in ohms until infinity. Reversed the
probes and it does the same thing. Sounds like the capacitor is OK to me.

I wanted to pull the electric motor loose from the case so I could see the
brushes and rotor. I removed all the mounting screws from everything I
could see, but I can't seem to pull the unit apart to get to the motor.
Everything is loose and I can twist the case a few degrees, but I can't pull
it apart.

Anybody know how I can get the motor out so I can look at its guts. Any
help is appreciated. Pretend I'm a dunce and be pretty specific.

Thanks,
Mike



It's probably still the start cap. Given the relatively low expense of
electrolytic capacitors, I'd just replace the start cap and see if that fixes
it. My guess is it will.

Take off the "bubble" on the side of the motor and look at the start cap. It may
obviously be defective, or maybe you can just get the numbers off it and take
them to Grainger or wherever you go to buy a new one. Easy to splice it back in,
simple fix. Even if that isn't the problem it won't hurt and it will probably
only cost you like $7.

GWE

Repair my Emglo AM78-HV4V air compressor
 

The only thing I can think of is the unloader (if your compressor has one).
If it's sticking, there may be too much back pressure, and the motor isn't
powerful enough to overcome it.

"Ignoramus26433" wrote in message
...
Like others, I cannot think of anything beside the cap.

i

On Sun, 15 Jan 2006 15:53:43 -0800, Mike S. wrote:
We were using our Emglo and shut it down for a lunch break. When we
came
back and tried to start it again all we got was a load electrical hum
and
sometimes it would pop our 15 amp breaker.

I pulled the compressor/electric motor unit loose from the rest of the
compressor so I could get to its guts. When I turned the fan blade by
hand
(it turned very easily) I could hear the compressor piston working. I
even
connected the AC power back up but still heard the hum. When I gave the
fan
a twist the motor started running the compressor. However, the motor
won't
start the compressor on its own.

I tried a quick test of the start-up capacitor with my multimeter and it
appears to be OK. It slowly climbs in ohms until infinity. Reversed
the
probes and it does the same thing. Sounds like the capacitor is OK to
me.

I wanted to pull the electric motor loose from the case so I could see
the
brushes and rotor. I removed all the mounting screws from everything I
could see, but I can't seem to pull the unit apart to get to the motor.
Everything is loose and I can twist the case a few degrees, but I can't
pull
it apart.

Anybody know how I can get the motor out so I can look at its guts. Any
help is appreciated. Pretend I'm a dunce and be pretty specific.

Thanks,
Mike




--

Repair my Emglo AM78-HV4V air compressor
 

Gary,

Thanks for the input. I'll try to find somebody local that can do a
heavy-duty test on this cap.

Mike

Repair my Emglo AM78-HV4V air compressor
 

Hi Grant,

It's probably still the start cap. Given the relatively low expense of
electrolytic capacitors, I'd just replace the start cap and see if that
fixes
it. My guess is it will.

Take off the "bubble" on the side of the motor and look at the start cap.
It may
obviously be defective, or maybe you can just get the numbers off it and
take
them to Grainger or wherever you go to buy a new one. Easy to splice it
back in,
simple fix. Even if that isn't the problem it won't hurt and it will
probably
only cost you like $7.

Well, not quite. I've been told by two repair houses that this cap costs
$50. I want to make sure it's dead before I replace it.

Thanks,
Mike

Repair my Emglo AM78-HV4V air compressor
 

Hi Bob,

The only thing I can think of is the unloader (if your compressor has
one).
If it's sticking, there may be too much back pressure, and the motor isn't
powerful enough to overcome it.

Don't think that's the case. When I removed the compressor/motor unit from
the rest of the compressor it also removed it from all the air tanks etc.
Like I said, spinning the compressor by hand was very easy. Its just that
the motor won't start on its own.

Thanks,
Mike

Repair my Emglo AM78-HV4V air compressor
 

In article ,
Mike S. wrote:
Hi Bob,

The only thing I can think of is the unloader (if your compressor has
one).
If it's sticking, there may be too much back pressure, and the motor isn't
powerful enough to overcome it.

Don't think that's the case. When I removed the compressor/motor unit from
the rest of the compressor it also removed it from all the air tanks etc.
Like I said, spinning the compressor by hand was very easy. Its just that
the motor won't start on its own.

That virtually guarantees that the problem is one of two things:
1) stuck/bad (open) centrifugal switch for the start windings on the motor
2) bad start cap.


I'd be tempted to try some 'impact engineering' to see if one can induce
the centrifugal switch to close. Proceed at your own risk. grin

Repair my Emglo AM78-HV4V air compressor
 

In article ,
Ignoramus7637 wrote:

I am surprised about the cost of caps that you were quoted. They
actually should cost a lot less. I have a few start caps that I bought
new for like $3 apiece, each about 180 uF. I can sell you a couple for
the same price, I have too many. If you arer local to Chicagoland, I
can loan you some.

Can you remove belt (if it is a belted compressor) and see if the
motor starts by itself without a load?

Another test is to put a pull rope in the pulley (with no compressor),
turn the AC power on, and try to start it like a gasoline engine. Or a
RPC without pony motor or caps.

Joe Gwinn

Repair my Emglo AM78-HV4V air compressor
 

We were using our Emglo and shut it down for a lunch break. When we came
back and tried to start it again all we got was a load electrical hum and
sometimes it would pop our 15 amp breaker.

I pulled the compressor/electric motor unit loose from the rest of the
compressor so I could get to its guts. When I turned the fan blade by hand
(it turned very easily) I could hear the compressor piston working. I even
connected the AC power back up but still heard the hum. When I gave the fan
a twist the motor started running the compressor. However, the motor won't
start the compressor on its own.

I tried a quick test of the start-up capacitor with my multimeter and it
appears to be OK. It slowly climbs in ohms until infinity. Reversed the
probes and it does the same thing. Sounds like the capacitor is OK to me.

I wanted to pull the electric motor loose from the case so I could see the
brushes and rotor. I removed all the mounting screws from everything I
could see, but I can't seem to pull the unit apart to get to the motor.
Everything is loose and I can twist the case a few degrees, but I can't pull
it apart.

Anybody know how I can get the motor out so I can look at its guts. Any
help is appreciated. Pretend I'm a dunce and be pretty specific.

Thanks,
Mike


Probably starting switch inside the motor that connects the cap to the
windings. Try tapping on the end bell of the motor when you try to
start it.... The "points" eventually get a bit pitted and blackened,
and typically cleaning them up is all it will need....
HTH
Ken.

Repair my Emglo AM78-HV4V air compressor
 

"Ignoramus7637" wrote in message
...
On Mon, 16 Jan 2006 21:02:59 -0500, Joseph Gwinn
wrote:
In article ,
Ignoramus7637 wrote:

I am surprised about the cost of caps that you were quoted. They
actually should cost a lot less. I have a few start caps that I bought
new for like $3 apiece, each about 180 uF. I can sell you a couple for
the same price, I have too many. If you arer local to Chicagoland, I
can loan you some.

Can you remove belt (if it is a belted compressor) and see if the
motor starts by itself without a load?

Another test is to put a pull rope in the pulley (with no compressor),
turn the AC power on, and try to start it like a gasoline engine. Or a
RPC without pony motor or caps.

Yes, that's a good test, but make sure that all rope is gone off the
shaft before you turn AC on (could sound obvious, but needs to be
said).


Lots easier just to give the pulley a spin by hand.

--

-Mike-

Repair my Emglo AM78-HV4V air compressor
 

"Ignoramus7637" wrote in message
...
I am surprised about the cost of caps that you were quoted. They
actually should cost a lot less. I have a few start caps that I bought
new for like $3 apiece, each about 180 uF. I can sell you a couple for
the same price, I have too many. If you arer local to Chicagoland, I
can loan you some.

Can you remove belt (if it is a belted compressor) and see if the
motor starts by itself without a load?

No belt. And when the motor/compressor unit was sitting on the bench it
still wouldn't start. If I gave the motor fan a spin and applied power it
started to run - although the start up time was very slow.

Mike S.

Repair my Emglo AM78-HV4V air compressor
 

"Mike Marlow" wrote in message
...

Lots easier just to give the pulley a spin by hand.


Already tried that. Motor starts, but very slowly.

Mike

Repair my Emglo AM78-HV4V air compressor
 

That virtually guarantees that the problem is one of two things:
1) stuck/bad (open) centrifugal switch for the start windings on the
motor
2) bad start cap.


I'd be tempted to try some 'impact engineering' to see if one can induce
the centrifugal switch to close. Proceed at your own risk. grin

I'd be glad to check the centrifugal switch - if I knew what it was and
where it's located. It's not on my exploded view diagram.

Mike

Repair my Emglo AM78-HV4V air compressor
 

Ken Sterling (Ken Sterling) wrote in message
...
Probably starting switch inside the motor that connects the cap to the
windings. Try tapping on the end bell of the motor when you try to
start it.... The "points" eventually get a bit pitted and blackened,
and typically cleaning them up is all it will need....
HTH
Ken.

So if that's the case, how do I get to them?

Mike

Repair my Emglo AM78-HV4V air compressor
 

Ken Sterling (Ken Sterling) wrote in message
...
Probably starting switch inside the motor that connects the cap to the
windings. Try tapping on the end bell of the motor when you try to
start it.... The "points" eventually get a bit pitted and blackened,
and typically cleaning them up is all it will need....
HTH
Ken.

So if that's the case, how do I get to them?

Mike


Mike,
Having trouble finding any kind of info on that particular model -
AM78-HV4V...... From your original post, it sounds like this is just
a motor, with a pulley, driving a larger pulley via a belt, as you
mentioned giving the "fan" a spin. Anyway, ya gotta locate the motor,
and take the end bell off to gain access to a centrifugal switch
internal to the motor. The switch has a set of contact points on it
which close with the motor at rest, putting the cap into the circuit.
When the motor starts up, centrifugal force causes the switch to open
up and takes the cap out of the circuit until it's needed for the next
start. Arcing, pitting, dust, dirt, etc., can keep the contacts from
making contact with each other when the motor is at rest. I suggested
tapping on the end bell of the motor when trying to start it as
sometimes that will let the contacts actually touch each other and get
the cap in the circuit to start the motor. That will tell you if the
cap is good or not as well as letting you know that the contacts are
dirty. I can't see the motor so it's hard to tell you how to take it
apart. Sorry.
Ken.

Repair my Emglo AM78-HV4V air compressor
 

If you were quoted $50 for a capacitor, I'd seriously try to find
another place to deal with - what exact value capacitor do you need?
did you check local electronics supply/surplus houses (be sure to say
it's a motor start capacitor) - the last one I bought (three days ago)
was 600 uf at 220VAC for $12, generally lower capacitance values are
less expensive.

Bill

www.wbnoble.com

to contact me, do not reply to this message,
instead correct this address and use it

will iam_ b_ No ble at msn daught com

Repair my Emglo AM78-HV4V air compressor
 

Hi Bill,

Don't have it in front of me any more. Sent it home with my brother. But,
if memory serves me correctly it's 60uF, 360VAC. The repair shop quoted
$50.00, the Emglo (DeWalt?) website quoted $43.00. Pretty pricey item, I
guess.

Mike