Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems.

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Default Photocopier - paper scratches on the OPC

ie the normal paper or dust slight scratches , not down to the metal drum
from loose screw or swarf. All quite normal for any OPC. Usually this is ok
but the original toner for this m/c not available, requiring second 1 only
source, supposed compatible, formulation. Very fine scratches seem to hold
the toner , ie exposed bits of latent image retain the toner in the
scratches and so deposit as fine lines on the paper. If too much toner
passed to the OPC then more and more lines appear, so only possible to
produce grey rather than black output. The ac cleaning voltage is now at
maximum of 2.5 KV but some lines are still present with a grey image rather
than black.
Anyone happen to know what needs adding to the toner to make it less sticky
or whatever ? or some other procedure. I'm assuming the narrow scratches are
physically holding the toner but thats only guessing really, decreasing the
transfer voltage of course produces a lighter image and still transfers the
lines, so not an option.
Physically cleaning the OPC or leaving the background heater on all the time
makes no difference. I'm wondering if the toner is too oily and decanting to
a tumbler with blotting paper lining would remove some of the oiliness,
before returning to the hopper. Anyone know of a test for oiliness that
gives some sort of numerical result ?

Incidently anyone know what the marking B stands for, on the preset for
adjusting the 200 to 250V dc voltage of the OPC relative to frame and what
this voltage is called ? The other presets are marked TR for transfer and AC
for the ac cleaning voltage


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Default Photocopier - paper scratches on the OPC

N_Cook wrote in message
...
ie the normal paper or dust slight scratches , not down to the metal drum
from loose screw or swarf. All quite normal for any OPC. Usually this is

ok
but the original toner for this m/c not available, requiring second 1 only
source, supposed compatible, formulation. Very fine scratches seem to hold
the toner , ie exposed bits of latent image retain the toner in the
scratches and so deposit as fine lines on the paper. If too much toner
passed to the OPC then more and more lines appear, so only possible to
produce grey rather than black output. The ac cleaning voltage is now at
maximum of 2.5 KV but some lines are still present with a grey image

rather
than black.
Anyone happen to know what needs adding to the toner to make it less

sticky
or whatever ? or some other procedure. I'm assuming the narrow scratches

are
physically holding the toner but thats only guessing really, decreasing

the
transfer voltage of course produces a lighter image and still transfers

the
lines, so not an option.
Physically cleaning the OPC or leaving the background heater on all the

time
makes no difference. I'm wondering if the toner is too oily and decanting

to
a tumbler with blotting paper lining would remove some of the oiliness,
before returning to the hopper. Anyone know of a test for oiliness that
gives some sort of numerical result ?

Incidently anyone know what the marking B stands for, on the preset for
adjusting the 200 to 250V dc voltage of the OPC relative to frame and what
this voltage is called ? The other presets are marked TR for transfer and

AC
for the ac cleaning voltage



I should have said the voltage on the centre of the revolving magnet
developer drum , not to the OPC, the retraction voltage ? The votage that
means the toner powder on the OPC that has become discharged from the
exposure light is pulled off, back to the toner supply side, leaving the
latent image.
These fine line toner deposits are adhering more than the 250V "retraction
voltage ?" will pull off but will pull off with the 7.3KV transfer voltage
to the paper.

Anyone know of a source of plain carbon black, fine ground, without silicone
oil/surfactants added , to dilute the supposed proper toner.


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Default Photocopier - paper scratches on the OPC

In that are is what looked like an afterthougt 1W resistor to ground,
marked brown black brown. Surely not if a few hundred volts there. With a
good light brought into the area I could then see it is brown black purple.
Just an ordinary looking MO resistor, enamelled ,no glass encapsulation, but
1 Gigohm.


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Default Photocopier - paper scratches on the OPC

In that are is what looked like an afterthougt 1W resistor to ground,
marked brown black brown. Surely not if a few hundred volts there. With a
good light brought into the area I could then see it is brown black

purple.
Just an ordinary looking MO resistor, enamelled ,no glass encapsulation,

but
1 Gigohm.


Wouldn't that be 100M? (10 x 10^7)


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Default Photocopier - paper scratches on the OPC

"William Sommerwerck" wrote in
:

In that are is what looked like an afterthougt 1W resistor to ground,
marked brown black brown. Surely not if a few hundred volts there.
With a good light brought into the area I could then see it is brown
black

purple.
Just an ordinary looking MO resistor, enamelled ,no glass
encapsulation,

but
1 Gigohm.


Wouldn't that be 100M? (10 x 10^7)




yes.

--
Jim Yanik
jyanik
at
kua.net


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Default Photocopier - paper scratches on the OPC

Jim Yanik wrote in message
...
"William Sommerwerck" wrote in
:

In that are is what looked like an afterthougt 1W resistor to ground,
marked brown black brown. Surely not if a few hundred volts there.
With a good light brought into the area I could then see it is brown
black

purple.
Just an ordinary looking MO resistor, enamelled ,no glass
encapsulation,

but
1 Gigohm.


Wouldn't that be 100M? (10 x 10^7)




yes.

--
Jim Yanik
jyanik
at
kua.net


I'm not used to seing that colour combination.
Measured about 1000Meg, by comparison with a glass cased 1Gohm , with a high
voltage source, it is grey not purple on the third band on rechecking.




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Default Photocopier - paper scratches on the OPC

N_Cook wrote:
ie the normal paper or dust slight scratches , not down to the metal drum
from loose screw or swarf. All quite normal for any OPC.


It's perfectly normal for the OPC to have mild scratches on it. As long
as it's not down to the metal. (Which will give you white lines along
the print.)

Usually this is ok
but the original toner for this m/c not available, requiring second 1 only
source, supposed compatible, formulation. Very fine scratches seem to hold
the toner , ie exposed bits of latent image retain the toner in the
scratches and so deposit as fine lines on the paper.


That's more likely to be due to dirt on the laser window. Give it a wipe
& a blow. A stray hair stuck in there, or in the laser window of the
cartridge will give you a line down the page.

If too much toner
passed to the OPC then more and more lines appear, so only possible to
produce grey rather than black output. The ac cleaning voltage is now at
maximum of 2.5 KV but some lines are still present with a grey image rather
than black.
Anyone happen to know what needs adding to the toner to make it less sticky
or whatever ? or some other procedure. I'm assuming the narrow scratches are
physically holding the toner but thats only guessing really, decreasing the
transfer voltage of course produces a lighter image and still transfers the
lines, so not an option.


There's nothing 'sticky' about the toner. It adheres to the drum from
electrostatic attraction only. If it's sticking to the drum when it
shouldn't be, there's something wrong with the HV, or the IR laser or
cleaning light is not wiping the charge from the drum as it should.

Physically cleaning the OPC or leaving the background heater on all the time
makes no difference. I'm wondering if the toner is too oily and decanting to
a tumbler with blotting paper lining would remove some of the oiliness,
before returning to the hopper. Anyone know of a test for oiliness that
gives some sort of numerical result ?


Dry toner is *never* 'oily'. It's micron-sized particles.

Incidently anyone know what the marking B stands for, on the preset for
adjusting the 200 to 250V dc voltage of the OPC relative to frame and what
this voltage is called ? The other presets are marked TR for transfer and AC
for the ac cleaning voltage


'B' = Bias.

--
W
. | ,. w , "Some people are alive only because
\|/ \|/ it is illegal to kill them." Perna condita delenda est
---^----^---------------------------------------------------------------
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Default Photocopier - paper scratches on the OPC

Bob Larter wrote in message
...
N_Cook wrote:
ie the normal paper or dust slight scratches , not down to the metal

drum
from loose screw or swarf. All quite normal for any OPC.


It's perfectly normal for the OPC to have mild scratches on it. As long
as it's not down to the metal. (Which will give you white lines along
the print.)

Usually this is ok
but the original toner for this m/c not available, requiring second 1

only
source, supposed compatible, formulation. Very fine scratches seem to

hold
the toner , ie exposed bits of latent image retain the toner in the
scratches and so deposit as fine lines on the paper.


That's more likely to be due to dirt on the laser window. Give it a wipe
& a blow. A stray hair stuck in there, or in the laser window of the
cartridge will give you a line down the page.

If too much toner
passed to the OPC then more and more lines appear, so only possible to
produce grey rather than black output. The ac cleaning voltage is now at
maximum of 2.5 KV but some lines are still present with a grey image

rather
than black.
Anyone happen to know what needs adding to the toner to make it less

sticky
or whatever ? or some other procedure. I'm assuming the narrow scratches

are
physically holding the toner but thats only guessing really, decreasing

the
transfer voltage of course produces a lighter image and still transfers

the
lines, so not an option.


There's nothing 'sticky' about the toner. It adheres to the drum from
electrostatic attraction only. If it's sticking to the drum when it
shouldn't be, there's something wrong with the HV, or the IR laser or
cleaning light is not wiping the charge from the drum as it should.

Physically cleaning the OPC or leaving the background heater on all the

time
makes no difference. I'm wondering if the toner is too oily and

decanting to
a tumbler with blotting paper lining would remove some of the oiliness,
before returning to the hopper. Anyone know of a test for oiliness that
gives some sort of numerical result ?


Dry toner is *never* 'oily'. It's micron-sized particles.

Incidently anyone know what the marking B stands for, on the preset for
adjusting the 200 to 250V dc voltage of the OPC relative to frame and

what
this voltage is called ? The other presets are marked TR for transfer

and AC
for the ac cleaning voltage


'B' = Bias.

--
W
. | ,. w , "Some people are alive only because
\|/ \|/ it is illegal to kill them." Perna condita delenda est
---^----^---------------------------------------------------------------



This is a conventional copier, not scanner/laser.
Silicone oil wick/baths at the output have not been used on photocopiers
since the days of sliding top ones, relying on silicones added (sub 1
percent) to the toner instead, not enough to appear oily to the touch but
enough to make sure paper does not stick to fuser drum or silicone rubber
pressure roller. The first one I came across to fix, was wet process toner
in paraffin carrier, 1970s vintage, paper on a roll and a vicious
guillotine.

The toner these days is mainly carbon/charcoal black but also such as
styrene ,styrene acrylic copolymer, polypropylene,metal complex dyes,
methylmethacrylate,styrene butylarylate, silicones and oleic acid


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Default Photocopier - paper scratches on the OPC

I found the neat little Murata corona generator, marked 4.55KV, 0.3mA . I
don't know what the o/p voltage should be
Corona measured as 8.7KV so something not right there, plenty of room to
drop the corona voltage. Not got to the point of monitoring the lines to it
yet nor tried the preset yet, lines to it are 2 grounds, supply, control,
and one marked REM , any ideas what that one means ?


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