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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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#1
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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 |
#2
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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. |
#3
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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. |
#4
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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) |
#5
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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 |
#6
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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. |
#7
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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 ---^----^--------------------------------------------------------------- |
#8
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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 |
#9
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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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