Re: Not DEC related but still hoping for some help: Problems w/ LJ 4+ Printer
On 4/9/19 9:23 PM, Ali via cctalk wrote: And you would be $10 richer now :D I just replaced the caps on the HV board ($5 worth of parts $7.99 for S :facepalm:) and it fired right up and started printing. None of the caps looked "bad". I don't have an ESR meter but when I tested the caps w/ my multimeter (outside of the circuit of course) only one seemed bad to my very rudimentary understanding. It was the big 25V 470uF cap. It never reached a resistance of infinity (which I believe a good cap will do). Not sure if this is a true indication of a bad cap or that my MM just couldn't charge the cap sufficiently. In either case it is now replaced w/ a 25V 470uF 125C Panasonic part. Thanks to everyone for the help. Cool! I'm glad that you got it working. :-) -- Grant. . . . unix || die
RE: Not DEC related but still hoping for some help: Problems w/ LJ 4+ Printer
> > It sounds like the caps have not (yet) completely failed. > > I'd bet $10 on the HV supply being your problem. And you would be $10 richer now :D I just replaced the caps on the HV board ($5 worth of parts $7.99 for S :facepalm:) and it fired right up and started printing. None of the caps looked "bad". I don't have an ESR meter but when I tested the caps w/ my multimeter (outside of the circuit of course) only one seemed bad to my very rudimentary understanding. It was the big 25V 470uF cap. It never reached a resistance of infinity (which I believe a good cap will do). Not sure if this is a true indication of a bad cap or that my MM just couldn't charge the cap sufficiently. In either case it is now replaced w/ a 25V 470uF 125C Panasonic part. Thanks to everyone for the help. -Ali
RE: Not DEC related but still hoping for some help: Problems w/ LJ 4+ Printer
>If I were you, I'd buy a complete DC/hv assembly, it must be cheap on ebay Where is the fun in that? :) To be honest I checked and it is about $50. Parts from mouser (w/ upgrades to 105c caps) are about $5 plus S I will try recapping and if that fails then I will consider buying a whole HV board.
Re: Not DEC related but still hoping for some help: Problems w/ LJ 4+ Printer
If I were you, I'd buy a complete DC/hv assembly, it must be cheap on ebay ---8<---Corte aqui---8<--- http://www.tabajara-labs.blogspot.com http://www.tabalabs.com.br ---8<---Corte aqui---8<--- Em qui, 4 de abr de 2019 às 12:39, Ali via cctalk escreveu: > > > You might want to order a few HV diodes because a leaky HV diode > > could be found if the caps are good. > > > > Thanks. I will keep that in mind. > > -Ali > >
RE: Not DEC related but still hoping for some help: Problems w/ LJ 4+ Printer
> You might want to order a few HV diodes because a leaky HV diode > could be found if the caps are good. > Thanks. I will keep that in mind. -Ali
Re: Not DEC related but still hoping for some help: Problems w/ LJ 4+ Printer
On 4/3/2019 9:44 AM, Jon Elson via cctalk wrote: First, since you have not checked with another cartridge, is to examine the corona wires and/or "combs" on the cart. Sometimes the wires break at one end. Also, toner spills could short it out, I've had that before. Bent contacts on the cart where it connects the HV to the printer could also be making bad/no contact. But, the caps could be it, the symptom where it starts working after warming up does indicate weak caps. You might want to order a few HV diodes because a leaky HV diode could be found if the caps are good. Jon
Re: Not DEC related but still hoping for some help: Problems w/ LJ 4+ Printer
On 04/03/2019 03:24 AM, Ali via cctalk wrote: Is the fuser roller warming up properly? Or, is it the corona supply is having trouble coming up to voltage? You should pull the bottom of the printer apart and thoroughly clean the PC board on both sides. If you have never done this, it will be a HUGE BLACK MESS with spilled toner dust - don't ask how I know this! Jon, Based on the info coming through on the list a "cold" fuser would produce toner that would wipe off/flake off of the printed sheet. This is not happening in my case so I am guessing the fuser is getting hot "enough". OK, sounds right. The current hive thinking seems to be toward the corona wire - specifically failing caps in HV needing time to warm up to specs before working properly. First, since you have not checked with another cartridge, is to examine the corona wires and/or "combs" on the cart. Sometimes the wires break at one end. Also, toner spills could short it out, I've had that before. Bent contacts on the cart where it connects the HV to the printer could also be making bad/no contact. But, the caps could be it, the symptom where it starts working after warming up does indicate weak caps. Jon
Re: Not DEC related but still hoping for some help: Problems w/ LJ 4+ Printer
On 04/03/2019 03:24 AM, Ali via cctalk wrote: Thanks for that tidbit. I didn't realize that a HV failure would not produce any error codes. If that is the case looks like I am recapping a board. Out of curiosity what symptoms were you getting? Nope, I think there is some sort of self-check on the fuser thermistors, but the corona supply is open-loop on most printers. There is also a self-check on the laser, as the beam has to hit a sensor to start the timing of the pixels. So a failed laser or polygon motor will cause an error. Good luck with it! Jon
RE: Not DEC related but still hoping for some help: Problems w/ LJ 4+ Printer
> It sounds like the caps have not (yet) completely failed. > > I'd bet $10 on the HV supply being your problem. Grant, I think that would be a good bet. I am going to order parts and recap the board... See where that gets us. Thanks for all of your help. -Ali
RE: Not DEC related but still hoping for some help: Problems w/ LJ 4+ Printer
> Just my little bit of input on this...the high voltage power supply is > just about the only thing that there is no error code for. I had one > fail and the printer didn't flag any errors. Changing the HV supply > fixed it. > > It sounds to me like your problem is related to the high voltage > supply. > > Dave Hi Dave, Thanks for that tidbit. I didn't realize that a HV failure would not produce any error codes. If that is the case looks like I am recapping a board. Out of curiosity what symptoms were you getting? Thanks. -Ali
RE: Not DEC related but still hoping for some help: Problems w/ LJ 4+ Printer
> Is the fuser roller warming up properly? Or, is it the > corona supply is having trouble coming up to voltage? You > should pull the bottom of the printer apart and thoroughly > clean the PC board on both sides. If you have never done > this, it will be a HUGE BLACK MESS with spilled toner dust - > don't ask how I know this! Jon, Based on the info coming through on the list a "cold" fuser would produce toner that would wipe off/flake off of the printed sheet. This is not happening in my case so I am guessing the fuser is getting hot "enough". The current hive thinking seems to be toward the corona wire - specifically failing caps in HV needing time to warm up to specs before working properly. -Ali
Re: Not DEC related but still hoping for some help: Problems w/ LJ 4+ Printer
On 04/02/2019 02:56 PM, Ali via cctalk wrote: I rescued a LaserJet 4+ printer that I have been trying to restore. Initially everything seemed ok and it seemed as if there may be just a bit of an issue with paper pickup which I attributed to old paper in the tray. However, soon I started getting the accordion paper jam which led me to replacing all the rollers including the transfer roller. Now the paper flows freely! However, I am having a new problem with printing. When I print, the first 5-10 pages initially come out blank. The printer does not produce any errors or error codes. The blank pages are warm (not hot though) as expected out of a LJ. After closer inspection it seems that the pages are printed SUPER light and gradually get darker the more I use the printer continuously. Eventually the printer starts printing continuous crisp black pages like new. This is a whole page phenomenon (i.e. not gaps, missing areas, etc.). Is the fuser roller warming up properly? Or, is it the corona supply is having trouble coming up to voltage? You should pull the bottom of the printer apart and thoroughly clean the PC board on both sides. If you have never done this, it will be a HUGE BLACK MESS with spilled toner dust - don't ask how I know this! I have a 5M, but I think the mechanism is the same. Jon
Re: Not DEC related but still hoping for some help: Problems w/ LJ 4+ Printer
On 4/2/19 4:20 PM, Ali via cctalk wrote: So I took out the HV board and it was super dirty (I added pictures on the thread in VCF at www.vcfed.org/forum/showthread.php?69109-Help-with-LJ-4-Printer-Repair-Please=564565 ). I saw. Nothing that should really prevent electrical flow but I cleaned it out anyhow. Re-installed and the issue remained. ACK While the printer was cold I ran another HV test and interestingly the toner drum had a very faint picture on the drum. So it looks like the toner is not being deposited on the drum appropriately until something "warms up". My gut tells me that there's something going on with the HV section and not actually pulling toner like it needs to. Given your comment below about the caps, I'm wondering if they are taking longer to charge up and the additional pages allow for them to charge to a sufficient level. The question now is, is this a toner problem (since I believe the corona wire is in the cartridge) or a HV problem. Since I am not getting error codes I am guessing the cartridge is bad for one reason or another How likely is that in your experience vs. the HV board going bad and just not erroring out? Two of the caps look like they may have leaked on the HV board (see the stains on the PCB in the before picture?). However, I don't see any bulging capacitors or anything blown. Thanks. It sounds like the caps have not (yet) completely failed. I'd bet $10 on the HV supply being your problem. -- Grant. . . . unix || die
Re: Not DEC related but still hoping for some help: Problems w/ LJ 4+ Printer
On 4/2/19 2:47 PM, Ali via cctalk wrote: Yes, these guys were built like tanks. This one acts as a 4M now because I added the PS module to it and it has local talk support. No duplexer or extra paper tray though :(. It was really a 4+. I picked it up for $1 ~ $10 at a ham fest. I then maxed the memory and added PostScript, thus turning it into a 4M+. The duplexer was interesting. It interfaced with the back of the printer in place of the fold down back cover. The extra paper tray was part of the duplexer and where the paper flipped around. - I think it went under the tray instead of out the top, then came back up and feed like the normal expansion tray. I will have to keep that in mind. This paper was old - not sure how old but it was in the tray when I found the printer on the side of the road. So better to recycle it then risk it I think. I'd be more worried about moisture with the paper. But, sure, recycle it and replace it. It may be "hot enough". They are certainly warm. And I don't detect them getting any hotter to touch as more printing goes on so this part could all be in my head. I don't remember the 4[M][+] ever getting all that warm. The 4Si, that would get really warm. Especially if you were using the job jogger, duplexing, and printing reams at a time. I can post it elsewhere if needed. It basically shows the picture getting darker with subsequent printings. I created an account, got logged in, and see both pictures. I don't see any typical roller related defects. I am not sure how to quantify it but it looks solid on the drum. I will have to repeat the test with a "cool" printer and see if it still looks solid or not. ACK Never thought about it but the extra toner (I assume not all the toner is being transferred to every page of print) must get swept up back in to the cartridge somewhere, no? I am guessing that you have an HV issue, and the toner is not coming out of the cartridge. Not too bad. It is worth mentioning that the printer doesn't seem abused in its old life either. Only 65K of prints... It's a younging. Both of which should produce an error usually... I thought so. However, Dave M. indicates that HV problems /won't/ produce an error. I thought about bad toner but that doesn't explain the improvement with time/prints. Or why it would go bad again after cooling down. That doesn't sound like a toner cartridge issue to me. I would say 5 - 10 minutes. Once I get good quality prints the subsequent pages all look great... That tells me that it's not something mechanical. I say that because it would be all the time. (I guess a cold solder joint could be mechanical. But I think that would present differently.) Thanks that was quick! I am pulling out the HV portion now to take a look. If I understand correct the DC (LV) supplies everything else except the engine. Those all seem to be working fine. Cleaning contacts is easy (and cheap) so that will be my first fix unless I see something glaringly obvious with the caps on the HV. Yep. He's retired. Thank you. You're welcome. -- Grant. . . . unix || die
Re: Not DEC related but still hoping for some help: Problems w/ LJ 4+ Printer
On 4/2/19 4:57 PM, Guy Dunphy via cctalk wrote: One other tip that might be useful. Very commonly with old photocopiers and laser printers the rubber pick-up and paper feed rollers lose their 'tack' and slip on the paper. I found that briefly soaking them in teatree oil restores the 'tack' quite well. It soaks in and seems to have the right spread of rubber-soluble oils to keep the surface a little tacky. Anyone else found other solvent/oils with similar effect? I've never considered oil / solvents. I'd worry about transference to paper. I have taken the rubber parts off and boiled them. Or at least put them in water as hot as I could get it. (You can only do so much when you put water in a blank CD spindle lid in the low wattage microwave at work.) This helps remove the accumulated acid from the paper. In doing so, the rubber becomes more tacky again. I found one boil cycle to yield good results. Two cycles slightly better. More than that and the RoI drops through the floor. -- Grant. . . . unix || die
Re: Not DEC related but still hoping for some help: Problems w/ LJ 4+ Printer
You could well have a temp sensitive HV supply or excess moisture in it that keeps the HT low until the warmth of operation dries it out. Given the problem returns each time, a temp sensitive HV sounds likely. Not sure how quickly you could remove and replace the supply but you might trying using freeze spray on the supply when the problem occurs and see if that fixes it temporarily. David Collins +61 424 785 131 > On 3 Apr 2019, at 11:38 am, Dave Mabry via cctalk > wrote: > > Ali via cctalk wrote on 4/2/2019 3:56 PM: >> I rescued a LaserJet 4+ printer that I have been trying to restore. >> Initially everything seemed ok and it seemed as if there may be just a bit >> of an issue with paper pickup which I attributed to old paper in the tray. >> >> However, soon I started getting the accordion paper jam which led me to >> replacing all the rollers including the transfer roller. Now the paper flows >> freely! However, I am having a new problem with printing. When I print, the >> first 5-10 pages initially come out blank. The printer does not produce any >> errors or error codes. The blank pages are warm (not hot though) as expected >> out of a LJ. >> >> After closer inspection it seems that the pages are printed SUPER light and >> gradually get darker the more I use the printer continuously. Eventually the >> printer starts printing continuous crisp black pages like new. This is a >> whole page phenomenon (i.e. not gaps, missing areas, etc.). >> >> A picture of the effect can be seen on VFC at: >> www.vcfed.org/forum/attachment.php?attachmentid=52120=1554074105 >> >> Sorry for the poor quality picture. >> >> Things I have checked/tried: >> >> 1. Using a brand new NOS toner (according to HP toner does not go bad as >> long as it was sealed - which this was) >> 2. Swapping the new transfer roller for the old one - same problem, I have >> to print out a bunch of pages until the printer starts acting normally. >> 3. I have checked the HV and an image is being transferred to the drum on >> the toner cartridge. >> 4. A visual inspection of the fuser shows it to be ok. >> >> Obviously this is happening printing demo pages so it has nothing to do with >> computer, OS, SW, drivers, etc. Anybody run into this before? Any >> ideas/suggestions. My Google fu turned up a bunch of discussions on the >> laser door not being aligned correctly but that would seem to be a more >> permanent issue i.e. unless you fixed the door no pages should print ever. >> Mine gets better on its own after a number of pages are printed. Plus the >> door and spring are fine - I checked them just in case. >> >> I tried posting on FixYourOwnPrinter.com but for whatever reason the site >> was not accepting the question. Any other forums you guys would recommend? >> TIA! >> >> -Ali >> > > Just my little bit of input on this...the high voltage power supply is just > about the only thing that there is no error code for. I had one fail and the > printer didn't flag any errors. Changing the HV supply fixed it. > > It sounds to me like your problem is related to the high voltage supply. > > Dave >
Re: Not DEC related but still hoping for some help: Problems w/ LJ 4+ Printer
Ali via cctalk wrote on 4/2/2019 3:56 PM: I rescued a LaserJet 4+ printer that I have been trying to restore. Initially everything seemed ok and it seemed as if there may be just a bit of an issue with paper pickup which I attributed to old paper in the tray. However, soon I started getting the accordion paper jam which led me to replacing all the rollers including the transfer roller. Now the paper flows freely! However, I am having a new problem with printing. When I print, the first 5-10 pages initially come out blank. The printer does not produce any errors or error codes. The blank pages are warm (not hot though) as expected out of a LJ. After closer inspection it seems that the pages are printed SUPER light and gradually get darker the more I use the printer continuously. Eventually the printer starts printing continuous crisp black pages like new. This is a whole page phenomenon (i.e. not gaps, missing areas, etc.). A picture of the effect can be seen on VFC at: www.vcfed.org/forum/attachment.php?attachmentid=52120=1554074105 Sorry for the poor quality picture. Things I have checked/tried: 1. Using a brand new NOS toner (according to HP toner does not go bad as long as it was sealed - which this was) 2. Swapping the new transfer roller for the old one - same problem, I have to print out a bunch of pages until the printer starts acting normally. 3. I have checked the HV and an image is being transferred to the drum on the toner cartridge. 4. A visual inspection of the fuser shows it to be ok. Obviously this is happening printing demo pages so it has nothing to do with computer, OS, SW, drivers, etc. Anybody run into this before? Any ideas/suggestions. My Google fu turned up a bunch of discussions on the laser door not being aligned correctly but that would seem to be a more permanent issue i.e. unless you fixed the door no pages should print ever. Mine gets better on its own after a number of pages are printed. Plus the door and spring are fine - I checked them just in case. I tried posting on FixYourOwnPrinter.com but for whatever reason the site was not accepting the question. Any other forums you guys would recommend? TIA! -Ali Just my little bit of input on this...the high voltage power supply is just about the only thing that there is no error code for. I had one fail and the printer didn't flag any errors. Changing the HV supply fixed it. It sounds to me like your problem is related to the high voltage supply. Dave
RE: Not DEC related but still hoping for some help: Problems w/ LJ 4+ Printer
Hello Guy, > Or the drum isn't getting charged in the first place, before light > exposure then toner dusting. > A way to check this: while the machine is in mid-copy, cut the power > then open it up and look at the drum. > Is there a toner image adhered to the drum section between where the > surface is image-exposed then dusted, and where it rolls against the > paper? As I alluded to in my OP I did do this test. When I looked at the drum after I start getting normal prints there is an image. However, at Grant's suggestion I also looked at it when the printer was first turned on. At this point there is very minimal toner adhering to the drum. As I print more and more an appropriate amount of toner seems to adhere to the drum explaining the improving picture. What I am trying to determine is now if this is a problem with a component in the cartridge (drum, corona wire, etc.) or is it with the HV supply board. > Btw, if the fuser roller isn't heated enough, the symptom is that the > paper comes out with a normal image, except > the toner wipes off with finger swipe. Since it's just sitting on the > paper not stuck to it. It is definitely not doing that. The toner is stuck on nice and tight - once it eventually gets there. > > Old toner cartridges should be given a strong end-to-end shaking before > being put into use. Toner can settle in > lumps and block the path to the duster. I have done this multiple times. However, the problem reappears. > While you have the machine apart, always clean all the optical path > lens surfaces. Dust greatly reduces the print contrast. And because > most machines use fan-blown air, dust gets everywhere that isn't > absolutely airtight sealed. I have done that as well. However, given that the quality improves with repeated printing and then falls back to none after 5 to 10 minutes of cooling I don't think dust is an issue. > One other tip that might be useful. Very commonly with old photocopiers > and laser printers the rubber pick-up and paper feed rollers lose their > 'tack' and slip on the paper. I found that briefly soaking them in > teatree oil restores the 'tack' quite well. It soaks in and seems to > have the right spread of rubber-soluble oils to keep the surface a > little tacky. > Anyone else found other solvent/oils with similar effect? I have never tried the oil/solvent trick. However, I did replace all the rollers on this printer due to a paper jam issue so I don't think that is the problem. Thanks for the input and the suggestions. -Ali -Ali
RE: Not DEC related but still hoping for some help: Problems w/ LJ 4+ Printer
> Since you are presumably going to keep this printer, once you fix it, > or > at least use it for large jobs where wasting the first few pages isn't > a > big issue, I would suggest getting another cartridge. > You will need it, eventually. > And, it provides a simple test to support or reject the in-the-crtridge > hypoothesis. > > Trying another cartridge is almost always one of the first tests. Fred, I am considering it but as my only source for a cartridge seems to be eBay it may not make much of a difference either way (in terms of having to wait for it to arrive and wondering if that's any good.. :)). I am going to order a cartridge anyhow and in the mean time I may just recap the board for good measure. Since this is not my usual cup of tea ordering parts is a pain. I am ordering one offs and then paying for S so the total cost is a pin compared to some guys who just have supplies in bins around... > > Those are sweet printers. Yes they are. Currently all of my main printers are rescues: a Color LJ 5500HDN, LJ 2100, LS 4Si and this one which is actually going to a family member once I can guarantee trouble free printing... -Ali > > > -- > Grumpy Ol' Fred ci...@xenosoft.com
RE: Not DEC related but still hoping for some help: Problems w/ LJ 4+ Printer
Or the drum isn't getting charged in the first place, before light exposure then toner dusting. A way to check this: while the machine is in mid-copy, cut the power then open it up and look at the drum. Is there a toner image adhered to the drum section between where the surface is image-exposed then dusted, and where it rolls against the paper? Btw, if the fuser roller isn't heated enough, the symptom is that the paper comes out with a normal image, except the toner wipes off with finger swipe. Since it's just sitting on the paper not stuck to it. Old toner cartridges should be given a strong end-to-end shaking before being put into use. Toner can settle in lumps and block the path to the duster. While you have the machine apart, always clean all the optical path lens surfaces. Dust greatly reduces the print contrast. And because most machines use fan-blown air, dust gets everywhere that isn't absolutely airtight sealed. One other tip that might be useful. Very commonly with old photocopiers and laser printers the rubber pick-up and paper feed rollers lose their 'tack' and slip on the paper. I found that briefly soaking them in teatree oil restores the 'tack' quite well. It soaks in and seems to have the right spread of rubber-soluble oils to keep the surface a little tacky. Anyone else found other solvent/oils with similar effect? Guy At 01:47 PM 2/04/2019 -0700, you wrote: >>If I'm not mistaken, high voltage capacitors on power supply. The corona wire >>isn't >charging the paper, so the image doesn't get transferred from the >>cylinder to the paper to >be pressed/fused in the fusor. > > >Alexander, > >Thanks for the reply. Grant also suggested the same thing. I am turning the >printer upside down as I write this to pull out the HV and see if anything >looks bad from the get go. Thanks! > >-Ali > > > >
RE: Not DEC related but still hoping for some help: Problems w/ LJ 4+ Printer
> > """ > - Bad / dirty contacts to the hi voltage > - Bad high voltage > - Bad DC power supply. > """ Grant, So I took out the HV board and it was super dirty (I added pictures on the thread in VCF at www.vcfed.org/forum/showthread.php?69109-Help-with-LJ-4-Printer-Repair-Please=564565 ). Nothing that should really prevent electrical flow but I cleaned it out anyhow. Re-installed and the issue remained. While the printer was cold I ran another HV test and interestingly the toner drum had a very faint picture on the drum. So it looks like the toner is not being deposited on the drum appropriately until something "warms up". The question now is, is this a toner problem (since I believe the corona wire is in the cartridge) or a HV problem. Since I am not getting error codes I am guessing the cartridge is bad for one reason or another How likely is that in your experience vs. the HV board going bad and just not erroring out? Two of the caps look like they may have leaked on the HV board (see the stains on the PCB in the before picture?). However, I don't see any bulging capacitors or anything blown. Thanks. -Ali
RE: Not DEC related but still hoping for some help: Problems w/ LJ 4+ Printer
>If I'm not mistaken, high voltage capacitors on power supply. The corona wire >isn't >charging the paper, so the image doesn't get transferred from the >cylinder to the paper to >be pressed/fused in the fusor. Alexander, Thanks for the reply. Grant also suggested the same thing. I am turning the printer upside down as I write this to pull out the HV and see if anything looks bad from the get go. Thanks! -Ali
RE: Not DEC related but still hoping for some help: Problems w/ LJ 4+ Printer
Grant, > I miss my 4M+ with duplexer and extra paper tray. :-( Yes, these guys were built like tanks. This one acts as a 4M now because I added the PS module to it and it has local talk support. No duplexer or extra paper tray though :(. > I've found that the age of the paper isn't as important as any dust > accumulated on the top sheet. I will have to keep that in mind. This paper was old - not sure how old but it was in the tray when I found the printer on the side of the road. So better to recycle it then risk it I think. > I thought that there was a temperature sensor to detect how hot the > fuser is and error if it's not warm enough. It may be "hot enough". They are certainly warm. And I don't detect them getting any hotter to touch as more printing goes on so this part could all be in my head. > I can't sign in to look at the picture. If I can, I'll look at it > later. I can post it elsewhere if needed. It basically shows the picture getting darker with subsequent printings. > How dark is the image that's being transferred to the drum? I am not sure how to quantify it but it looks solid on the drum. I will have to repeat the test with a "cool" printer and see if it still looks solid or not. > If the normal image is being transferred and toner is being consumed, I > would wonder where the toner is going. Never thought about it but the extra toner (I assume not all the toner is being transferred to every page of print) must get swept up back in to the cartridge somewhere, no? > > How clean / dirty is the fuser cleaning pad? Not too bad. It is worth mentioning that the printer doesn't seem abused in its old life either. Only 65K of prints... > The things that come to mind are shifting High Voltage (…) and > temperature. Both of which should produce an error usually... > > The other thing that comes to mind is possibly toner caked up in the > toner cartridge. I thought about bad toner but that doesn't explain the improvement with time/prints. Or why it would go bad again after cooling down. > > How long can you wait after getting a good printout before they start > to > fade again? (Assuming the printer stays on.) I would say 5 - 10 minutes. Once I get good quality prints the subsequent pages all look great... > I'll share your email with a friend who was a certified HP LaserJet > repairman. (I just pretended to be one a couple of jobs ago). ... > My friend replied with the following: >""" > - Bad / dirty contacts to the hi voltage > - Bad high voltage > - Bad DC power supply. > > > -- Thanks that was quick! I am pulling out the HV portion now to take a look. If I understand correct the DC (LV) supplies everything else except the engine. Those all seem to be working fine. Cleaning contacts is easy (and cheap) so that will be my first fix unless I see something glaringly obvious with the caps on the HV. Thank you. -Ali
Re: Not DEC related but still hoping for some help: Problems w/ LJ 4+ Printer
On 4/2/19 2:09 PM, Grant Taylor via cctalk wrote: I'll share your email with a friend who was a certified HP LaserJet repairman. (I just pretended to be one a couple of jobs ago). My friend replied with the following: """ - Bad / dirty contacts to the hi voltage - Bad high voltage - Bad DC power supply. """ -- Grant. . . . unix || die
Re: Not DEC related but still hoping for some help: Problems w/ LJ 4+ Printer
On 4/2/19 1:56 PM, Ali via cctalk wrote: I rescued a LaserJet 4+ printer that I have been trying to restore. I miss my 4M+ with duplexer and extra paper tray. :-( Initially everything seemed ok and it seemed as if there may be just a bit of an issue with paper pickup which I attributed to old paper in the tray. I've found that the age of the paper isn't as important as any dust accumulated on the top sheet. However, soon I started getting the accordion paper jam which led me to replacing all the rollers including the transfer roller. Now the paper flows freely! Ya. However, I am having a new problem with printing. When I print, the first 5-10 pages initially come out blank. The printer does not produce any errors or error codes. The blank pages are warm (not hot though) as expected out of a LJ. I thought that there was a temperature sensor to detect how hot the fuser is and error if it's not warm enough. After closer inspection it seems that the pages are printed SUPER light and gradually get darker the more I use the printer continuously. Eventually the printer starts printing continuous crisp black pages like new. This is a whole page phenomenon (i.e. not gaps, missing areas, etc.). What‽ I would question if there is an issue with the High Voltage and transferring from the transfer roller to the paper. But you said you checked the High Voltage. I thought the printer would detect this error condition too. A picture of the effect can be seen on VFC at: www.vcfed.org/forum/attachment.php?attachmentid=52120=1554074105 Sorry for the poor quality picture. I can't sign in to look at the picture. If I can, I'll look at it later. Things I have checked/tried: 1. Using a brand new NOS toner (according to HP toner does not go bad as long as it was sealed - which this was) 2. Swapping the new transfer roller for the old one - same problem, I have to print out a bunch of pages until the printer starts acting normally. 3. I have checked the HV and an image is being transferred to the drum on the toner cartridge. How dark is the image that's being transferred to the drum? If the normal image is being transferred and toner is being consumed, I would wonder where the toner is going. How clean / dirty is the fuser cleaning pad? 4. A visual inspection of the fuser shows it to be ok. This doesn't sound like a fuser issue that I recall. Unless it's not warm enough. (Again, the printer should detect this.) Obviously this is happening printing demo pages so it has nothing to do with computer, OS, SW, drivers, etc. Agreed. Anybody run into this before? Any ideas/suggestions. My Google fu turned up a bunch of discussions on the laser door not being aligned correctly but that would seem to be a more permanent issue i.e. unless you fixed the door no pages should print ever. Agreed. Mine gets better on its own after a number of pages are printed. Plus the door and spring are fine - I checked them just in case. So, it needs to be something that can change while the printer is operating. The things that come to mind are shifting High Voltage (…) and temperature. The other thing that comes to mind is possibly toner caked up in the toner cartridge. How long can you wait after getting a good printout before they start to fade again? (Assuming the printer stays on.) I tried posting on FixYourOwnPrinter.com but for whatever reason the site was not accepting the question. Any other forums you guys would recommend? TIA! I'll share your email with a friend who was a certified HP LaserJet repairman. (I just pretended to be one a couple of jobs ago). -- Grant. . . . unix || die
Re: Not DEC related but still hoping for some help: Problems w/ LJ 4+ Printer
If I'm not mistaken, high voltage capacitors on power supply. The corona wire isn't charging the paper, so the image doesn't get transfered from the cylinder to the paper to be pressed/fused in the fusor. ---8<---Corte aqui---8<--- http://www.tabajara-labs.blogspot.com http://www.tabalabs.com.br ---8<---Corte aqui---8<--- Em ter, 2 de abr de 2019 às 16:56, Ali via cctalk escreveu: > I rescued a LaserJet 4+ printer that I have been trying to restore. > Initially everything seemed ok and it seemed as if there may be just a bit > of an issue with paper pickup which I attributed to old paper in the tray. > > However, soon I started getting the accordion paper jam which led me to > replacing all the rollers including the transfer roller. Now the paper > flows > freely! However, I am having a new problem with printing. When I print, the > first 5-10 pages initially come out blank. The printer does not produce any > errors or error codes. The blank pages are warm (not hot though) as > expected > out of a LJ. > > After closer inspection it seems that the pages are printed SUPER light and > gradually get darker the more I use the printer continuously. Eventually > the > printer starts printing continuous crisp black pages like new. This is a > whole page phenomenon (i.e. not gaps, missing areas, etc.). > > A picture of the effect can be seen on VFC at: > www.vcfed.org/forum/attachment.php?attachmentid=52120=1554074105 > > Sorry for the poor quality picture. > > Things I have checked/tried: > > 1. Using a brand new NOS toner (according to HP toner does not go bad as > long as it was sealed - which this was) > 2. Swapping the new transfer roller for the old one - same problem, I have > to print out a bunch of pages until the printer starts acting normally. > 3. I have checked the HV and an image is being transferred to the drum on > the toner cartridge. > 4. A visual inspection of the fuser shows it to be ok. > > Obviously this is happening printing demo pages so it has nothing to do > with > computer, OS, SW, drivers, etc. Anybody run into this before? Any > ideas/suggestions. My Google fu turned up a bunch of discussions on the > laser door not being aligned correctly but that would seem to be a more > permanent issue i.e. unless you fixed the door no pages should print ever. > Mine gets better on its own after a number of pages are printed. Plus the > door and spring are fine - I checked them just in case. > > I tried posting on FixYourOwnPrinter.com but for whatever reason the site > was not accepting the question. Any other forums you guys would recommend? > TIA! > > -Ali > > > >
