hybridfree/eevblog-posts huggingface dataset:
HP 'Bill West' leaf springs: where do they go to? - Page 1
Forum section: electronics / repair

author: Bill Woodbridge
author_rank: Contributor
timestamp: March 19, 2024, 09:57:58 am
content: I wondered if anyone had any thoughts on what must be a fairly common occurrence with vintage HP equipment featuring the ‘Bill West’ leaf spring switches?In what’s now become my standard procedure, before doing much else on a newly-acquired HP 3456A bench voltmeter I removed the front panel and unscrewed the PCB with its 37 Bill West switches. The state of the switches was worse than I’d ever encountered before: some completely floppy, some dead stuck, some graunchy …. On inspection, some of the leaf springs had popped out of the tiny ridges at either the plunger (white) or body (red) end, all were rusty and caked in dried-on old lubricant, just about all had a distinct kink at the plunger end, and worst of all 4 were missing altogether.I started the laborious process of extracting them all, cleaning the springs in an ultrasonic bath and cleaning the switches with IPA. Meanwhile I mechanically deconstructed the instrument pretty much entirely, down to subchassis level, which revealed one of the missing springs near the lip of the front panel housing, and another which dropped out onto the floor from an unknown location. The other two were nowhere to be found, although I can easily make replacements for them (I posted on this separately a while ago).But it’s still a big worry to me that in such an instrument there are probably two small pieces of bare metal floating about somewhere, potentially able to cause chaos or worse, danger. I suppose they might have been lost when it was opened for a previous repair, as it clearly had been, but then again maybe not. Does anyone else have any thoughts / experience on how to proceed, other than to hope for the best?Thanks as always for any help.

author: TERRA Operative
author_rank: Super Contributor
timestamp: March 19, 2024, 11:19:00 am
content: Take all the panels off the instrument and give it a good shake in all directions and orientations until your arms hurt, then cross your fingers and close your eyes when you power it back on.

author: Bill Woodbridge
author_rank: Contributor
timestamp: March 19, 2024, 12:47:16 pm
content: Many thanks! First two stages already done, final stage pending ...
HP BNC 1250-0212 where can I Buy, replace with other screw-in type BNC - Page 1
Forum section: electronics / repair

author: yuhar
author_rank: Contributor
timestamp: November 04, 2022, 04:19:50 pm
content: The Amphenol 112720 almost identical, but not fully (solder pin, extra o-ring)- Where is it available, primarily in Europe?This type of connectors are all 27mm long and, I can't screw it all the way in;https://eu.mouser.com/ProductDetail/Rosenberger/51K504-200N5?qs=ehM%252BESVsXgz23tVtyJlogg%3D%3DThe original connector only 24 mm long together; 11 mm from the nut - inside the device.Does anyone know of another solution without a washer?Screw-in type BNC; not a frequent connector.
HP C4810A inkjet print head ID chip pinout? - Page 1
Forum section: electronics / repair

author: hanakp
author_rank: Regular Contributor
timestamp: August 06, 2021, 06:38:02 pm
content: I know it's a long shot, but maybe someone will know: I'm trying to find some info about pinout and communication protocol on HP11 inkjet print heads, specifically on black variant C4810A. I'm not actually interested in the nozzle array, but about ID chip that stores serial number etc. It even has 4 separate pads on the pogo connector. We have old full-color powder 3D printer Zprinter 650 which uses 5 of these heads for color binders. But suddenly, the heads last only 25-40% of their expected life and then throw "head check error", meaning the printer is unable to communicate with the ID chip. It may be just a bad head batch (or they're counterfeit), but it also may be a problem within the printer (maybe overvoltage transients fry the chips?). I already throughly cleaned pogo contact board and replaced carriage flex cable, but the problem persists. Plus, each head costs about 60 EUR and I don't want to waste them needlessly. They're pretty well hidden inside the print carriage, so any info would make debugging much easier. I found several HP head pinouts online, but none of them has an ID chip:https://spritesmods.com/?art=inker&page=2https://ytec3d.com/hp45-inkjet-printhead/https://sudonull.com/post/31720-Hacking-an-HP-color-cartridge-turning-it-into-a-handheld-printerI also tried searching HP patents about it, but no luck.

author: amyk
author_rank: Super Contributor
timestamp: August 07, 2021, 09:28:03 pm
content: Get a cheap logic analyser (the FX2LP "Saleae clones" will be sufficient) and examine the protocol. Beware that print heads may have higher voltages for the actual printing elements (e.g. Epson piezo heads have a 42V ramp signal.)
HP C7280 not printing black - Page 1
Forum section: electronics / repair

author: PaulAm
author_rank: Frequent Contributor
timestamp: April 20, 2022, 03:50:16 pm
content: Anyone here ever fix one of the HP C7280 inkjet multifunction printers?I have one that stopped printing black. Even with a new HP cartridge nothing black prints. The printer thinks it's printing, but there's nothing on the paper. Doing the print head cleaning cycle (multiple times) doesn't change anything.Doing a google search on this yields a couple million hits but no effective technical advice. The summary would be a) return to HP for service or b) buy a different printer. I'd rather fix the one I have rather than adding to the landfill problem. Anyone got any pointers?

author: m3vuv
author_rank: Super Contributor
timestamp: April 20, 2022, 06:52:29 pm
content: had the same issue with a cannon once,ended up using a shringe with some plastic tubing to shrynge hot water into the small nipple where the ink tank passed ink into the print head,did it about 6 or 7 times untill clear water came out of the ink nozzles ,dried it out refited the ink cartrige and it was fine.

author: tooki
author_rank: Super Contributor
timestamp: April 21, 2022, 03:18:38 pm
content: If I recall correctly, this is one of the HP models that uses dual vacuum pumps for nozzle maintenance (one that sucks from the nozzle side, like most inkjets have, but also a second one to suck from the back, to back out clogs rather than try and force them through the nozzle). Most likely, the pumps are also used to prime the whole system. If there’s a leak or a pump has failed, then the ink isn’t going to make it out of the cartridge.
HP Compaq LA2405wg Monitor repair - Page 1
Forum section: electronics / repair

author: sairfan1
author_rank: Frequent Contributor
timestamp: July 10, 2020, 01:48:30 am
content: Attached is picture of power supply board from HP Monitor (LA2405wg) when i power it on its power light blinks in green color, it gives a small splash of picture and some sound from power supply, then screen gets black, and it continuously happens, splash, sound, screen black, splash, sound screen black...When i googled, i came to know that these monitors often have issue that their capacitors get leak and from top they pup out, but when i opened my monitor its capacitors looks good, (visually) at some forums i read that they may also get dry out, and in that case we can not see anything visually.I want to know what else i can check, I'm not an expert so please little bit explain how can i test advised things. thanks

author: Rasz
author_rank: Super Contributor
timestamp: July 10, 2020, 11:13:51 am
content: caps sure look great, design not so muchlook at the pcb discoloration around the diodes, those suckers are cooking 5 caps around themchanging those 5 caps without measuring anything would be my first quick diagnostics move

author: sairfan1
author_rank: Frequent Contributor
timestamp: July 10, 2020, 04:09:07 pm
content: I have Chinese capacitors with me, do you recommend to try to fix it by those?

author: chegueva01
author_rank: Contributor
timestamp: July 10, 2020, 04:36:30 pm
content: hi , i'm no expert either but if there is nothing visually , black color or smell of burn , then i'll just relax and see how the pro's handle this. sorry for the useless comment ;p

author: Rasz
author_rank: Super Contributor
timestamp: July 10, 2020, 04:39:44 pm
content: Quote from: sairfan1 on July 10, 2020, 04:09:07 pmyes, even salvaged ones from some other piece of electronic, the purpose is to quickly diagnose if that is the problem. Replacing caps is faster than measuring, still have to desolder, then measure, then solder back in place, why not skip a step
hp cp1515n laserjet  issues - Page 1
Forum section: electronics / repair

author: p.larner
author_rank: Frequent Contributor
timestamp: February 28, 2024, 05:07:31 am
content: I have the hp cp1515n laser printer,its stopped working on my pc,it works ok on an old lappy runing xpsp3 but in win 10 on my desktop give errors and wont print,the troubleshooter just says printer error!,ive renewed the cable and reinstalled the win 10 drivers but still no fix,any ideas?,i dont want to replace the printer as i have spare toners,when it works its a good printer,i am at my wits end help!.

author: SeanB
author_rank: Super Contributor
timestamp: February 28, 2024, 08:27:38 am
content: Sadly Win10 updated drivers most likely, and the new drivers are not working with the printer. Best bet is to download the Win8 drivers, and force Win10 to use them, which will likely work. I have not bought printers or scanners recently, only getting those that stopped working with Win10 and up, because MS decided to stop supporting old working hardware. Another solution is to use, as it is the networked version, the ethernet connection, just connect it, look up the IP address, and download the HP network driver set for it, and that will work perfectly. As a bonus all computers can use it then.If still an issue connect via the network, and set up the driver for the old Laserjet 4MV, and the IP and port 9100, and use PCL5 as the print language, as that will work with all the HP network printers, and will set the page parameters as the printer has them. Did that with a few, as the new printer was given same IP address, and thus no need to change the very painful driver setup per client to work with a new driver, as this software was very unhappy with printers, but that 4MV setting worked with all the PCL printers, even those that were Canon made.

author: p.larner
author_rank: Frequent Contributor
timestamp: February 28, 2024, 12:13:32 pm
content: For some strange reason i moved the printer nearer to the tower,i had it running thru a usb extension lead,without that it works ok,its funny but i have 3 usb extension cables 2 of them are 1.5 meters long and a 5 meter one,it does the same with all 3 of them!.
hp cp1515n - Page 1
Forum section: electronics / repair

author: m3vuv
author_rank: Super Contributor
timestamp: March 04, 2020, 10:18:50 am
content: This is a longshot but thought id ask,long story short i mixed the toner cartrige chips up by mistake,is there any wat to try and read them to figure out what goes where?,i imagine its 1c2 coms as there are only 2 contacts?,cheers in advance.

author: coromonadalix
author_rank: Super Contributor
timestamp: March 04, 2020, 12:31:41 pm
content: Some Samsung toner brand have 2 pins, but it's an resistor hidden inside, this resistor is blown making you think the toner is out of service / many printed pages ...worth to check

author: shakalnokturn
author_rank: Super Contributor
timestamp: March 04, 2020, 01:31:10 pm
content: The HP 125A cartridges use a 1 wire communication not a fuse resistor.The original HP chips seem to be black blob type, I came across a chip on my refurbished black cartridge that had a few more components to look at but was not able to identify the I.C. used.I've tried communicating with the "chip" using my universal programmer with the DS2431 protocol without luck.The simplest solution would be to order a set of new chips, refill your toner so the page count makes sense, they'll come identified by colour.Edit: Attached photos."IOP" is for In/Out pinCaptures are those of communication between printer and cartridge.

author: m3vuv
author_rank: Super Contributor
timestamp: March 04, 2020, 05:19:30 pm
content: the problem is all the chips are the same colour,i see no way to id them,they all have part numbers but a google search brings uo ziltch!.

author: shakalnokturn
author_rank: Super Contributor
timestamp: March 05, 2020, 12:04:28 pm
content: What are their part numbers?When I unbury my colour MFC I may go to the trouble of pulling the chips to check their numbers if that can help.

author: m3vuv
author_rank: Super Contributor
timestamp: March 06, 2020, 01:09:34 pm
content: these are 2 of the part numbers i have :c9j003s : d8p033s,these are the ones i need to id,cant lay hand to the others at the mo,cheers m3vuv.73

author: shakalnokturn
author_rank: Super Contributor
timestamp: March 06, 2020, 02:23:58 pm
content: Here are the codes on the original HP toner chips I have:Yellow: AAP014SMagenta: B37043SCyan: A9F042SI'm not sure this is going to help much...I have 2 cheap black cartridges, codes don't follow the HP scheme.

author: shakalnokturn
author_rank: Super Contributor
timestamp: March 06, 2020, 02:28:29 pm
content: You could place the chips on the cartridges randomly, test cartridge combinations in printer until it stops grumbling about them being swapped.Once it will allow you to print, output a test page to determine how the chips need swapping back.
HP cracked knob and chipped display cover repair/adhesive recommendations - Page 1
Forum section: electronics / repair

author: ChuckDarwin
author_rank: Regular Contributor
timestamp: September 23, 2022, 05:16:30 pm
content: Back to the "someday" items, two plastic repairs...- Cracked HP knob--level adj knob, so low torque in both the grub screws and application. Single full front to back crack, no too bad yet. If the gap was bigger I would probably try JP Weld Plastic Bonder (tan) and put it in a vac bag. My current thought is to wick in something like Tenax-7R/Same-Stuff from the inside. Any idea if it will even adhere or be too agressive with the plastic?- Other plastic repair is a clean edged chip in a HP 5335A display cover, right at the "5335" printing, thus needs to be a clean mating. Fortunately this is an opaque section of the cover. A retention clip locks just to the right so I could put some reinforcement behind part of the chip if needed. Recommended glue for this--maybe watch crystal cement?

author: strawberry
author_rank: Super Contributor
timestamp: September 23, 2022, 11:12:17 pm
content: maybe pure cyanoacrylate (capillary)
HP DesignJet 510 - Faulty HP-GL/2 formater card - Page 1
Forum section: electronics / repair

author: Mroq
author_rank: Newbie
timestamp: August 13, 2022, 10:30:58 pm
content: Hey,I have recently got a HP DesignJet 510 plotter, which is a model without integrated formater, instead with HP-GL/2 add-in card.When powered, system is getting stuck in the middle of initialization. Service manual says that this part is related to "loading part of software".Reading manual again told me that my HP-GL/2 might be faulty - red status light is still while should be blinking. Indeed removing the card makes ploter go through initialization and even makes test prints. Never the less, formater is a must as it proces jobs sent from a computer.All this (both with some internet dig-up) tells me that possibly ROM chip on this card is faulty. Would anybody be so nice to share a dump of content of that memory chip?There were two models of HP-GL/2 (not cross compatible), mine is as on the picture.Of course it might be not the ROM but as on example one (or more) of four RAM chips on the backside.
HP DPS-1125ABA Power supply dead maybe - Page 1
Forum section: electronics / repair

author: Sabot68
author_rank: Newbie
timestamp: November 01, 2020, 01:44:10 am
content: HI all,First time poster so be kind!I was lucky enough to acquire 2x HP Z820 workstations from my work place, they were going to be thrown out so I guess its classed as a pre-dumpster dive rescue!After the installation of a pcie wifi adapter the Z820 would not turn back on, the only thing that had changed from when I had turned it off to when I tried to turn it back on was the installation of that pcie card. Lucky I had two of the Z820 and swapped out the PSU and the computer booted up and operated normally.I did think that I had isolated the issued, a dead psu, a Delta electronics DPS-1125ABA REV 04, however after opening it up, doing a basic visual inspection (no bulging caps) and checking a fuse with my multimeter, then plugging it in to power (while still on my desk out of the computer) it looks to be working. The cooling fans at the back spin up and the green led lights up. I'm at work currently so I can not swap it back into the computer, I will do when I get home.I have not measured voltages yet as I dont have pinouts or schematics, oh and my experience level is somewhere between beginner and intermediate, i.e. I get nervous working anywhere near 240v stuff.Does anybody have experience with these PSU and/or can provide me with schematics and pin outs, google has not been very helpful.ThanksAndrew
HP durant switch replacement - Page 1
Forum section: electronics / repair

author: coppercone2
author_rank: Super Contributor
timestamp: November 30, 2019, 02:58:52 am
content: my precision supply had a broken switch, which I took apart. the spring shot out some where and I ended up destroying plastic pins.hate this fucking thing, anyway does anyone have a solution to replace the 48211-468 switches?almost want to replace it with a relay matrix or something before I decide to throw this thing out totallyhorrible switch design too, could have had a retention plate in there so this does not happen preferably something modern, I don't mind making another panel riveted to the front of the unit.. if it has decent switches, or even needing a lookup table to program it with a pushswitch matrix (laminated note). perhaps I will just replace it with a potentiometer.mods can delete this, unless you want to leave a note for future designers of what not to do. the precision network can eat shit and its going to get 2 potentiometers like a real power supply, since i repaired a wago crimper i cannot deal with springs anymore, haha i am fucking laughing right now boy my hands hurt, at least the power supply is not sticking out of a drywall right nowif you wanna know whats wrong with it, the spring fits on a little triangle for some reason with no retention and it fits on another triangle with a pathetic brass insert (looks like a baby milipede) that makes a shady amount of contact with a little pcb that looks like it belongs on king tuts necklace. and its all flimsy plastic, then its improperly soldered and press fit into a comb on another pcb with little solder fillets holding it together (hey this is not how soldering or brazing works, it works on a lap joint principle, this is how garbage is assembled), hp should have designed a real swtich for this precision application rather then being cheap skates and reusing random trash for resistance controlled shit (granted the lowest value in the divider is 40ohms but for this dinky garbage switch oh my)i bet if i even managed to clean and repair this thing, that switch matrix is still a ticking time bomb
HP E 2378A DVM - Page 1
Forum section: electronics / repair

author: wings515
author_rank: Newbie
timestamp: October 24, 2023, 04:01:05 pm
content: I had this DVM sitting on top of my freezer doing a test on a heated bird bath and my wife opened the door. Down came the meter and now when measuring resistance it either shows OL or 00.0. Nothing in between for any resistance value.Any hints on what could be wrong? The AC and DC function and continuity audio are correct. I have not tried the current function at this time.

author: coromonadalix
author_rank: Super Contributor
timestamp: October 24, 2023, 04:20:48 pm
content: manual no schematics, may helpthe dial maybe broke etc ...https://hirokun.jp/av/e2378a_man.pdfand maybe some teardown videos of it, you could see some details
HP E1938A OCXO repair - Page 1
Forum section: electronics / repair

author: wkb
author_rank: Super Contributor
timestamp: July 15, 2025, 07:37:06 am
content: In case anyone is interested outside of the time-nuts community: I recently repaired an HP E1938A OCXO whose oven did no longer warm up. These OCXO are normally part of telco GPSDO, in my case I only have the OCXO itself, not the GPSD parts.Write-up with pictures can be found athttps://people.freebsd.org/~wilko/HP-OCXO-E1938A/Wilko
HP E3630A Output Drops to Zero Intermittently - Fixed - Page 1
Forum section: electronics / repair

author: Dave Wise
author_rank: Regular Contributor
timestamp: October 18, 2019, 09:26:14 pm
content: Something to watch for. If C27 leaks - even a tiny bit, not visible - it will dissolve the solder mask beneath the cap, allowing electro-migration between two traces that go through there. One is the -5V reference, and if they short, you will lose all three outputs. I replaced the reference and a couple other parts before I looked hard at the physical PCB layout, following the -5V traces around. If all your outputs are low or zero, I think C27 is the first thing to check. Unsolder it and look at the board underneath.Hope this helps some other E3630A owner,Dave Wise

author: Dave Wise
author_rank: Regular Contributor
timestamp: October 22, 2019, 03:55:34 pm
content: I had three false starts before I discovered the leakage. Since the proximate cause of losing all outputs was the -5V reference line, I replaced the LM336. No change. Then I found a 2N2222 whose goal in life is to ground -5V if -12V fails. Replaced it. No change. Then I followed the trace around looking for resistors which could short it if their conformal coating was bad. Found several suspects, re-soldered with prying to give clearance. No change. The last trace segment went under C27 (4700/25, reservoir for +5V display supply) and I noticed the slightest discoloration. Took off the cap (which was not bulging) and it was a sad mess underneath. I cleaned with IPA scrub and dried, scratched away the bridge, recoated with nail polish. Now the instrument is fine and might outlive me.Dave
HP E3631A Power Supply bad display/output, potential data issue? - Page 1
Forum section: electronics / repair

author: Dereku3
author_rank: Newbie
timestamp: July 21, 2024, 02:27:03 pm
content: Hi all,I picked up this PS recently that the seller said it "turned on and seemed to work". But unfortunately there was a bit more to it than that...I have thoroughly searched the forum first, and although there are many similar symptoms I don't believe this exact problem has presented itself (or I'm just dumb)The unit powers up and passes self tests without error - but gives 2 beeps.The rotary switch and all buttons are responsive (can hear the clicks), all display segments work.When setting a display limit, the rotaty switch is able to configure all decimal places without issue.However when the outputs are enabled the +25v reads as -41.37v/2.339a, the -25v as +41.40v / 2.355a and the 6v as 1.000v / 8.839a.Connecting a DMM to the outputs they all read 0v, no amount of adjusting the larger digits do anything to the displayed voltage or measured voltage.However if I highlight the XX.X0v last decimal of +25 or -25 I get 2 large steps in the measured output when using the rotary switch. 0v to 10v and then 20v (-10v and -20v) - but still no change on the display.Trying to perform a cal, it will accept the 6v cal, but fails on the +25/-25. However once exited from the calibration screen the the 6v remains at 0v;unless I highlight the X.XX0a last decimal on the current side and rotate until the little CV changes to CC. And this point the measured output reads -0.270v.Pulling the cover off I tested all bias and reference voltages. All are within spec. U3 in the ADC is outputting +10v -10v as expected.R4 and R5 are good, along with R15 and R16.Moving to the DAC circuit; measuring the CV/CC Ref of all outputs show a change between 0v and 2.7v, although in the same big 2 steps.No output from +6V CV Ref, but the +6V CC Ref shows activity.Looking at the input at Pin-3 of U13 on the scope I can see a stepped analog signal - and it does change in responce to the above findings that only the last decimal provides any impact (albeit incorrect) on the output voltage/current.Attempting to adjust any other digit on any other voltage or current outputs shows no change on this pin.This makes me think that U13 is functional, as it's responding correctly to what little output is coming from the DAC.The data present at Pin-7 of U12 is the same as Pin-2 of U11 - so I believe U11 is passing the signal correctly.But I cannot see any significant change of the data pulse when adjusting the settings - but I'm not sure I would with my 100mhz DSO?There is a chance the DAC/U12 is faulty, but it seems weird that it would still output what looks like a coherient signal; just missing most of the actual data.So I feel that U11/U12 and U13 are all functional. And instead the actual DAC Data from Pin-15 of U16 is actually bad/corrupt.But I'm not sure of the relationship between U16 and U17 the microcontroller, and any other potential feedback circuits that might be causing an issue.Some pointers would be appriciated. I don't really want to shotgun change all ICs at this point!
HP E3632A FIRMWARE - Page 1
Forum section: electronics / repair

author: Ussovak
author_rank: Contributor
timestamp: June 10, 2020, 02:10:03 pm
content: Below is the firmware for U13 of HP E3632A. I read U13 (which is an AM27C020-150JC PLCC32) of my recent purchase of an HP E3632A. The tag on U13 reads as E3632A-0060016 U13 REV 1.1.If anyone has a newer version, please share.

author: tuanpq
author_rank: Newbie
timestamp: October 02, 2025, 03:05:25 am
content: can you upload 8051 gpib firmware?
HP E4406A OS problem - Page 1
Forum section: electronics / repair

author: R-1125F
author_rank: Regular Contributor
timestamp: May 22, 2023, 03:34:11 pm
content: I have an HP E4406A that will not boot properly. The OS is HP-RT. When it boots it tells me that files and directories cannot be found. I tried to use the HP E4406A firmware update software through the ethernet port. The software can communicate with the processor board. The update software completes and says that the update was successful, but the E4406A screen says it can't erase the memory and create new files (errno = 5). This uses flash ram and not a hard drive. I don’t know if this is a software or hardware problem.I haven't found a way to communicate directly with the processor through the ethenet port. I think I need to restore the OS somehow, but I don't know how to do that. The processor board is similar to the one used in the HP 16702A logic analyzer. It has ethernet and 488 ports available. I am totally lost here.Could someone give me an idea on how to communicate with the processor without an IP address?

author: m k
author_rank: Super Contributor
timestamp: May 27, 2023, 07:58:37 pm
content: Through Ethernet port it is a packet protocol of some sort.So the receiving end must know how to react.Maybe you're just missing a voltage somewhere.

author: R-1125F
author_rank: Regular Contributor
timestamp: June 09, 2023, 09:33:50 pm
content: Thank you for the reply.I have determined the operating system (HP-RT) is just gone. I have no idea how to replace it. This is essentially an HP9000 computer.Anybody know how to replace the OS?
HP Elite E271i monitor disassembly - Page 1
Forum section: electronics / repair

author: CambridgeMart
author_rank: Regular Contributor
timestamp: October 22, 2021, 07:29:49 pm
content: I bought a faulty HP E271i monitor for a low price with the intent to repair it. It does actually power up, but shuts down after 30s or so. There doesn't seem to be much in the way of service information on this monitor, but I have located the end-of-life disassemblty manualhttp://h22235.www2.hp.com/hpinfo/globalcitizenship/environment/productdata/Countries/_MultiCountry/disassembly_monito_20138623051838.pdfI've managed to remove the stand and have removed the 2 screws shown in (9), but step (10) is not at all as easy as lifting the cover off! Has anyone worked on one of these monitors?

author: amyk
author_rank: Super Contributor
timestamp: October 22, 2021, 11:46:42 pm
content: There are clips around the edge. This is typical for monitors and you can barely see them in the images in that document. A thin flat tool should be able to release them.

author: CambridgeMart
author_rank: Regular Contributor
timestamp: October 23, 2021, 06:17:34 pm
content: I can see what look like clips in the photos, but I cannot locate them in the gap between the front and rear sections. Using a thin stainless steel spudger, there's no obvious give anywhere on either side that would indicate a clip.

author: lunacyworks
author_rank: Contributor
timestamp: October 24, 2021, 08:44:55 am
content: I had a version of that monitor, I replaced/upgraded the led backlight in it. I recall there being some thin double-sided tape on the back of my unit that was between the back that held the boards and the front that held the LCD. I lifted it from the bottom and gently pried the two parts apart. Be careful as you can easily damage the shielding on the back of the LCD if forced or you get one tape and there happens to be another.It could have been it was just excess tape that was used to hold down one of the ribbon cables connecting the LCD and control boards.Either when you go to remove the back, lift up from the bottom part of the monitor and push the back cover forward towards the top of the monitor as you lift.I don't recall it being like this type ()

author: CambridgeMart
author_rank: Regular Contributor
timestamp: October 25, 2021, 05:39:06 pm
content: The hidden feature that enables you to remove the back is hidden under 2 little square 'bumps' at the bottom of the rear cover, if you insert a screwdriver through the opening on the RHS, the back pops loose. Wedge the back open with a guitar pick or spudger and do the same thing on the other side. Once it's loose, you can use a spudger to release all the clips along the left, right, and lower edges (5 each side and 8 along the bottom).This doesn't appear to be documented anywhere that's readily accessible!
HP ESA-L1500A Front panel issue - Page 1
Forum section: electronics / repair

author: little_carlos
author_rank: Regular Contributor
timestamp: October 10, 2019, 11:16:24 pm
content: Hi.I got today this spectrum analyzer and I got issues with the front panel.The only keys that work are "Preset" from system, the "on" button and the knob for the sweep delay.The screen shows no issues as it shows all info working properly, and the input works fine since I was capable of doing some small measurements.I tested the ribbon cable and the cable of the membrane buttons and they show no issue, as well as continuity of each membrane to the connector and they all show possitive results.Any advice? Would it be possible of connecting a PS/2 keyboard and use it to control the analyzer instead of getting in the trouble of repairing it? the owner manual doesnt show any info of what functions can be accessed with the external keyboard.Thanks for your time.
HP ESG E4420B display problem - Page 1
Forum section: electronics / repair

author: Stefano76
author_rank: Newbie
timestamp: May 10, 2021, 11:26:35 am
content: Hi everyone,I'm trying to repair an HP ESG E4420B signal generator with no video on display (all black, but backlight is working), I think the the problem is in the VLCD voltage witch is not correct,should be a negative voltage of about -6V and is not..Can someone tell me witch transistor is Q601?It's have a code M1LH written on it but I'm not sure if is a MMBT6429LT1G or something else.Thank you in advance,Stefano.

author: maximvs
author_rank: Newbie
timestamp: November 01, 2021, 02:58:16 pm
content: Stefano,Any luck with this ? Did you fix the display ?

author: DeepLink
author_rank: Regular Contributor
timestamp: November 04, 2021, 05:59:35 am
content: Q601 = MMBT6429LT1
HP Folio 9470m battery reset - Page 1
Forum section: electronics / repair

author: ustaad
author_rank: Contributor
timestamp: August 31, 2024, 06:41:24 pm
content: Hello guys,I have an HP Elitebook Folio 9470m laptop whose battery was only providing around 1 hr of backup so I decided to open the battery and check individual cell capacity to know if there was only 1 bad cell to be replaced. So I charged and discharged each individual cell using a battery tester module to their capacity. Unfortunately all four of the cells were at same capacity as all were degraded with time so decided to repack and continue using this battery until its end of life.But when I reconnected it back to laptop it neither charges nor gives any backup despite showing battery status as available and "plugged in" in Windows status bar. The status light turns on for only 2-3 seconds when I connect the charger and then turns off indefinitely until I disconnect and connect again.It assume that because of charging/discharging individual cells there is some kind of tamper detection triggered in BMS and now I need to reset that trigger to make it working again. The battery connector to laptop has eight pins. Marked from left to right as 2 pins -ve rail, BI, T, C, D and 2 pins +ve rail. There is no voltage between -ve and +ve or between -ve and any other pin. However I can measure voltage between connector's -ve and each cell's individual voltage. However there are arbitrary voltages between +ve and BI, T, C and D pins.Right now all four Lipo cells are charged up to 4.1 V each and it is showing 89% charged in Windows. I have uninstalled/reinstalled drivers as well as tried pressing power button for 30 seconds after removing the battery as I got these suggestions from Google search. There is no setting in the BIOS as well.Attaching pictures below for reference,
HP Infinium 54845A strange problem need help! - Page 1
Forum section: electronics / repair

author: analogRF
author_rank: Super Contributor
timestamp: September 30, 2018, 08:49:38 pm
content: I've got an older HP branded 54845A which was failing several tests and all calibrations. I have fixed everything up. Replaced the hard drive with a compact flash, fresh install of the software and all the upgrades up to V4.5 and added memory (64MB now from 16MB before). Cleaned up the ADC ASICs and replaced an on board regulator chip and a couple of capacitors (on acquisition board) and now the scope passes all self tests (multiple times), passed all calibrations and everything is honky dory except a peculiar issue that was also there in the beginning when I got the scope (it was win95 and SW V3.72)As you can see in the pictures, when the graphic display is enabled, all is fine and the scope works perfectly as far as I can tell. As soon as I disable the graphic display (top right corner) the waveform is cut into pieces as you can see. The issue is very visible on fast time bases but it also exists on slow time bases specially with low frequency square wave it is very visible.For the life of me I cannot figure out what can be wrong with it. I don't think it is the acquisition board. When I got the scope I thought it was a software/driver issue so I replaced the clunky noisy hard drive and upgraded the software but the problem persists. The only hardware issue I can think of is the display board on the PCI slot but what is in there to test?Can someone with this model scope please check and see if the scope shows the same waveform when the graphic display is disabled?

author: AJ3G
author_rank: Regular Contributor
timestamp: June 05, 2019, 01:43:15 am
content: Hello:Wonder if you figured out what was causing this problem. I just posted the same exact issue with another 54845A.

author: analogRF
author_rank: Super Contributor
timestamp: June 05, 2019, 01:30:32 pm
content: the problem was in the HP graphics interface board (sitting next to the video card) which connects to the acquisition board.I made an extender and took it out and probed around but unfortunately I could not find the problem and there were severalcustom programmed PLDs on that board too...anyways, long story short I found that board on ebay for $30-40 (don't remember exact value)and replaced it and the scope worked perfectly.that original interface board had a LOT of bodged wires going around but they were all clearly factory made. it looked likea very early test board on somebody's bench at HP!
HP L2335 Monitor (Pixelworks PW172-30V Scaler) - Page 1
Forum section: electronics / repair

author: Sceptre
author_rank: Regular Contributor
timestamp: May 28, 2020, 05:17:25 am
content: I have an HP L2335 Monitor that won't start up. The power LED (green) illuminates when AC is applied, but there is no picture (not just no backlight) or response to key presses. DC rails from the power supply board look OK.Service manualhttps://www.electronica-pt.com/esquema/monitores/aoc-esquema-monitor/aoc-service-manual-hp-l2335_a00-monitor-lcd-13887/troubleshooting chart says to check for key scans. The OE for that buffer (CS0, which comes straight from the PW172 scaler device) appears to be stuck high. So I check power to the scaler; all rails look good. Clock (14ish MHz) is present. Mode bits are in the states indicated by the schematic. No sign of reads from the EEPROM (even on AC power up), but the scaler is reading flash (AT49BV8192AT-12TC) - there's activity on ROMOE (~G) and some address and data lines. It appears to be cyclical and continually repeating, based on the trace on my analog scope. No apparent activity on the scaler's RS-232 port.If I had access to a logic analyzer, I'd take a closer look at the flash accesses, to see if it's polling for some missing signal. I haven't found firmware online for this monitor, so if the flash is corrupted, I'm out of luck. Another possibility is that the CS0 line is open between the scaler and the key buffer (so it's cycling in the key scan but not getting any presses), but that would likely be an open connection at the BGA (I don't have a rework station either). There's a board available on ebay, I could take a flyer on that.Any tips, insight, etc. on this model?Thanks!
HP laptop charger with intermittent voltage - Page 1
Forum section: electronics / repair

author: rodrigopires
author_rank: Regular Contributor
timestamp: April 18, 2022, 09:41:47 pm
content: I got a HP laptop charger that presents intermittent voltage and makes a clicking sound at the same time voltage drops (as if there was a spark somewhere...). All the caps seem to be in good shape and i see no damage component/mark.I uploaded a video showing the behavior with the link:https://youtube.com/shorts/nlccgf4GAMw?feature=shareIs this a comon problem? (I have never seen it) Any gesses? Thanks!

author: m3vuv
author_rank: Super Contributor
timestamp: April 19, 2022, 06:17:30 am
content: possibly a good idea to remove it from its housing and power it on in the dark and look for any arcs.

author: wraper
author_rank: Unknown
timestamp: April 19, 2022, 06:21:11 am
content: Likely a small electrolytic capacitor on PWM controller VCC failed.
HP Laptop won't turn on with voltages presence - Page 1
Forum section: electronics / repair

author: SickPick
author_rank: Newbie
timestamp: September 30, 2020, 09:54:42 pm
content: Hello guys, I recently bought a broken laptop for so cheap but with learning purposes, I would really like to know more and more about this things but I'm stuck in this issue and I hope that someone could help me here...So, as I was saying, I bought this laptop and the problem was the fact that it had no lights on, no signals of life whatsoever. I disassembled it and checked for voltages and turned out that my main 19v power rail was missing after the first mosfet... So I took it down and jumped a wire and, in fact, now I have the charger light and I also have 19v and 3,3v everywhere i checked but when I short the pins from the power up button, all I get is a light which usually is on when the laptop is on, but not only the laptop is not coming on also when I stop shorting those pins, the light goes off.I know there is an issue where if there is a short between the middle pin with + the laptop won't just turn on, but I think that's not the case here since I have no short there...Now, I'm thinking that the problem in the SuperIO but as far as I know, if it was dead I should not get that light on, is that right?I also wanna mention that I got told that could actually be a short on the 5V power rail and that's could be the reason of the light to be on when I short those pins but it doesn't turn on because the SuperIO it's cutting down the power for that ipothetical 5V short... I know the method of the voltage injection is very useful but I only have a 15V 1A Max power supply and it has short protection, so it's cutting down the power when I work on a shorted board...I would really like to get some help here if anyone can... I bought this and other laptops like this to learn how to do repairs and I've been successful with several, but this... Maybe this is just too much for my knowledgle...Sorry so much for my english, I'm Italian and I'm doing my best and... Thanks in advance!
HP LaserJet M9040 dark Panel, no image - Page 1
Forum section: electronics / repair

author: rvalente
author_rank: Frequent Contributor
timestamp: October 26, 2021, 06:23:07 pm
content: Hello Mates,I've a M9040 at the office, few years ago the control panel died but, we kept using through ethernet, no one used the scanner anyway. Suddenly it seems the network config was off, could not find its IP any more so, time to fix the panel (yeah, great...)The display is blank in all contrast range, no image during the turn-on/warm-up process. The touch and the keyboard are responsive, If I press copy the scanner and printer works normally.I was playing with the board and resetted the LCDs flat cables while the board, once the image came back perfect for a few seconds, the printer finalizing the boot/warm-up and it went dark again. I'm suspecting of a poor power supply for the contrast. The photos does not make justice but its possible to see something very dark in the upper left corner (ready/warming, but in portuguese).The control board is made by Optrex japan, is a XILINX FPGA + Epson LCD controller (seems to handles the touch and the display).The comms with the formatter board (name given for the printer motherboard) seems to be clock + data in + data out, the service manual gives little to no information on schematics, attached the few useful shots. The 24V and 3V3 signals are fine.Anyone has any idea or tip for where to start?
HP MFP M476dw Colour Laser - Page 1
Forum section: electronics / repair

author: Tangent_Tracker
author_rank: Regular Contributor
timestamp: December 19, 2022, 03:50:18 pm
content: Hi, just been given the above printer with a fuser error 50.2. So followed all the advice of plugging into a wall socket etc to no avail.Pulled the fuser out and it would seem that the element has a resistance of about 60R, which would seem about right for its type. Not able to check thermisters as i didn't have any wires handy that would sit in the plugs.Checked the voltage and it sat at about 136 then during startup it went up to 240. Trouble is this is without the load of the fuser of course...Sooo, given people's experience with these machines, can the fuser element appear ok but then sort of break down when current flows? Or is it more likely I am looking at a more problematic fault here?Had to put it all together for now as need the room but I might put a flying lead on the fuser element so that I can measure the current flowing and see if voltage stays at 240v. In hindsight I should have felt for warmth straight after the test which might have helped...Any thoughts appreciated. Looks to be a real nice laser but not knowing on the general condition not sure how much effort to go to!Thanks

author: TheMG
author_rank: Frequent Contributor
timestamp: December 19, 2022, 06:27:51 pm
content: It is possible for any heating element to present a fault only when warm, as metals expand and contract with changes in temperature.Another possibility is that the element and its switching circuitry are fine, but that the temperature sensor(s) are at fault.

author: coromonadalix
author_rank: Super Contributor
timestamp: December 19, 2022, 08:35:21 pm
content: https://www.metrofuser.com/post/50-2-fuser-error-on-hp-laser-printers

author: Swake
author_rank: Frequent Contributor
timestamp: December 23, 2022, 04:17:33 pm
content: Got the same printer since many years now. Works well with 'alternative' toners. Only major issue we have is the auto feed for the scanner. Manual scanning still works.Replacing the fuser is a 5min job:

author: Tangent_Tracker
author_rank: Regular Contributor
timestamp: January 02, 2023, 10:09:32 pm
content: Thanks, I have had a fuser out but it tests ok. I am going to try running it on flying leads so I can measure the voltages and then I'll take it from there. I can see you can get replacement fuser units so this will be an option. I just have to be 100% sure before committing any money!Olly.

author: asis
author_rank: Frequent Contributor
timestamp: January 04, 2023, 03:24:23 pm
content: Quote from: Swake on December 23, 2022, 04:17:33 pmOnly major issue we have is the auto feed for the scanner. Manual scanning still works.@SwakeThis is a typical fault for the MFM HP series.You need to get to the wiring harness twisted in pairs.They tend to break when opening the ADF cover frequently.In my practice, I changed all the wires to softer ones and made the tourniquet a little longer.