HP DeskJet 500
 

Our church has one of these printers that has worked well for a long time.
It now doesn't.

Upon turning on the power, it appears to go through the power up testing,
but then when trying to move the head, it powers down. I have checked and
watched the power supply and I suspect that it's being told to turn off. I
checked ESR on all the electrolytics, and all appear to be fine. I can move
the head to the middle, and upon powering up, it will take it home, but then
shut down once it gets there. I measured about 5v across the head motor, so
I pulled it out and put 5v to it. It does run, but not very smoothly, and
sometimes doesn't want to start very well. I don't know if this motor has
brushes or not, but it feels like maybe the motor is struggling, thereby
shutting down the power supply. If I unhook that motor plug, upon power up,
the printer flashes an error.

Any more thoughts here? Maybe something I missed?

WT

HP DeskJet 500
 

"Wayne Tiffany" writes:

Our church has one of these printers that has worked well for a long time.
It now doesn't.

Upon turning on the power, it appears to go through the power up testing,
but then when trying to move the head, it powers down. I have checked and
watched the power supply and I suspect that it's being told to turn off. I
checked ESR on all the electrolytics, and all appear to be fine. I can move
the head to the middle, and upon powering up, it will take it home, but then
shut down once it gets there. I measured about 5v across the head motor, so
I pulled it out and put 5v to it. It does run, but not very smoothly, and
sometimes doesn't want to start very well. I don't know if this motor has
brushes or not, but it feels like maybe the motor is struggling, thereby
shutting down the power supply. If I unhook that motor plug, upon power up,
the printer flashes an error.

Any more thoughts here? Maybe something I missed?

Even I would say it's possibly time to retire it. :)

I've found bad solder connections in the power supply of one of those.

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HP DeskJet 500
 

"Sam Goldwasser" wrote in message
...
"Wayne Tiffany" writes:

Our church has one of these printers that has worked well for a long
time.
It now doesn't.

Upon turning on the power, it appears to go through the power up testing,
but then when trying to move the head, it powers down. I have checked
and
watched the power supply and I suspect that it's being told to turn off.
I
checked ESR on all the electrolytics, and all appear to be fine. I can
move
the head to the middle, and upon powering up, it will take it home, but
then
shut down once it gets there. I measured about 5v across the head motor,
so
I pulled it out and put 5v to it. It does run, but not very smoothly,
and
sometimes doesn't want to start very well. I don't know if this motor
has
brushes or not, but it feels like maybe the motor is struggling, thereby
shutting down the power supply. If I unhook that motor plug, upon power
up,
the printer flashes an error.

Any more thoughts here? Maybe something I missed?

Even I would say it's possibly time to retire it. :)

I've found bad solder connections in the power supply of one of those.

--- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/
Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
+Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
| Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html

Important: Anything sent to the email address in the message header above
is
ignored unless my full name AND either lasers or electronics is included
in the
subject line. Or, you can contact me via the Feedback Form in the FAQs.

I thought about the solder and so checked all joints under the microscope -
all looked good. I really think the controller is telling it to shut down
since it is so repeatable. I can watch the voltage shut off when the head
reaches the home position.

WT



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HP DeskJet 500
 

Wayne Tiffany wrote:

I thought about the solder and so checked all joints under the microscope -
all looked good. I really think the controller is telling it to shut down
since it is so repeatable. I can watch the voltage shut off when the head
reaches the home position.

Considering the cost of cartridges it would be a blessing to retire it !

Graham

HP DeskJet 500
 

On Mon, 26 Jun 2006 12:38:28 -0500, "Wayne Tiffany"
put finger to keyboard and composed:

Our church has one of these printers that has worked well for a long time.
It now doesn't.

Upon turning on the power, it appears to go through the power up testing,
but then when trying to move the head, it powers down. I have checked and
watched the power supply and I suspect that it's being told to turn off. I
checked ESR on all the electrolytics, and all appear to be fine. I can move
the head to the middle, and upon powering up, it will take it home, but then
shut down once it gets there. I measured about 5v across the head motor, so
I pulled it out and put 5v to it. It does run, but not very smoothly, and
sometimes doesn't want to start very well. I don't know if this motor has
brushes or not, but it feels like maybe the motor is struggling, thereby
shutting down the power supply. If I unhook that motor plug, upon power up,
the printer flashes an error.

I may have a spare motor for this model. If so, then you can have it
for the cost of postage from Australia. What is its part number?

Any more thoughts here? Maybe something I missed?

WT

I believe there may be an encoder strip which may need cleaning.

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.

HP DeskJet 500
 

Hi!

I really think the controller is telling it to shut down
since it is so repeatable. I can watch the voltage shut off when
the head reaches the home position.

If memory serves, these are just a permanent magnet DC motor--not a stepper
type or anything quite that fancy. The positioning is done by way of the
encoder strip. In other words, it could well have built up a short circuit
by way of either conductive whiskers or something that has broken and
changes position just enough to cause trouble. Maybe the components
responsible for driving the motor don't start to break down until they've
been loaded for a while?

When that happens, the controller might just shutdown on overload, instead
of burning up.

I've never had one of the carriage motors quit, but some of mine have had
the spring that holds the belt tightly in place start to back off. When this
happens, the printer may make "twanging" or "gritty" noises like gears
stripping. If it gets bad enough, the controller shuts down and lights
flash.

I would think that taking the motor out, cleaning it well and putting it
back might solve the whole problem. Even today these printers have a lot of
life left in them and the ink can be downright cheap compared to a new unit!

William

HP DeskJet 500
 

I considered that but the motor is constructed with the crimp type on the
ends, not fasteners. I have my eye on a newer printer (Hp DJ932C) that is
probably available, and if it works, I will tear into the motor on the 500
just to see what's what.

WT

"William R. Walsh" m
wrote in message news:Oc3og.6446$FQ1.3679@attbi_s71...
Hi!

If memory serves, these are just a permanent magnet DC motor--not a
stepper
type or anything quite that fancy. The positioning is done by way of the
encoder strip. In other words, it could well have built up a short circuit
by way of either conductive whiskers or something that has broken and
changes position just enough to cause trouble. Maybe the components
responsible for driving the motor don't start to break down until they've
been loaded for a while?

When that happens, the controller might just shutdown on overload, instead
of burning up.

I've never had one of the carriage motors quit, but some of mine have had
the spring that holds the belt tightly in place start to back off. When
this
happens, the printer may make "twanging" or "gritty" noises like gears
stripping. If it gets bad enough, the controller shuts down and lights
flash.

I would think that taking the motor out, cleaning it well and putting it
back might solve the whole problem. Even today these printers have a lot
of
life left in them and the ink can be downright cheap compared to a new
unit!

William





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