hybridfree/eevblog-posts huggingface dataset:
LCD PS repair (17PW06-2) - Page 1
Forum section: electronics / repair

author: rodrigopires
author_rank: Regular Contributor
timestamp: April 02, 2021, 10:07:37 pm
content: I have a lcd tv with no power on, no standby light, no sound, no image, nothing... looked in the PSU and found a blown IC (IC303 - ICE3BR0665J) and a shorted diode (D321 - SB5B0) replaced those two and still not fixed. I got 210v on pin 5 IC303 and 2.5v on the 12v aux from TR300. Same with the other transformer TR200 with 213V on pin 1 and 2.7v on pin 2 (24v aux). Primary side is OK at 400V. What could be the source of the problem?

author: fzabkar
author_rank: Super Contributor
timestamp: April 03, 2021, 02:08:08 am
content: What voltages do you measure at PL200 and PL201?BTW, I would replace all 4 parallel connected UF5402 diodes as a set. If any diode has a slightly lower forward voltage drop, it could end up carrying all the current.

author: coromonadalix
author_rank: Super Contributor
timestamp: April 03, 2021, 07:37:53 am
content: yeah a cheap way to boost the current capacity

author: mikerj
author_rank: Super Contributor
timestamp: April 03, 2021, 10:23:42 am
content: Quote from: rodrigopires on April 02, 2021, 10:07:37 pmAre these static DC levels or is the output of IC303 actually switching and you are getting the average voltage via a DMM? Having a constant DC drop of ~190v across the primary of that flyback transformer suggests it's open circuit. It will have a fairly low DC resistance so there would be smoke and flames if there was continuity.

author: rodrigopires
author_rank: Regular Contributor
timestamp: April 18, 2021, 05:21:38 pm
content: I dont have an osciloscope to check the waveform my only tool is a DDM, in dc mode i get a more or less contant 210V and in AC mode it jumps from 0 to around 307V and back to 0 on and on about one time a second, using frequency mode i wasn't able to get a reading... Also the 2.5v i get on the 12v AUX were mesured in AC mode, using DC mode it does not show a reading. I dont know what more to check...Also replaced the remaining 3 diodes but with no change.
LCD Screen Flashes White - Repair - Page 1
Forum section: electronics / repair

author: ReedTriesToRepair
author_rank: Contributor
timestamp: March 06, 2024, 08:19:03 pm
content: I'm trying to repair an old DAQ screen. I repaired the power supply inside of it, but when I went to put the screen back on, about 9 times out of 10 it blinks white twice when the computer is powering on. I have taken a video to show the phenomenon:https://youtu.be/0n47fGii72kIt appears to depend on the cables. I have tried reseating all of the connectors twice and it still happens. Every once in awhile I get to see the computer booting up, but only on a very artifact-filled screen. I'm not too familiar with LCD screen circuit layouts. Any clues which connectors to focus on?

author: inse
author_rank: Super Contributor
timestamp: March 06, 2024, 10:08:38 pm
content: This video is private…

author: ReedTriesToRepair
author_rank: Contributor
timestamp: March 08, 2024, 11:26:55 pm
content: Sorry just noticed. It is available now!

author: Jwillis
author_rank: Super Contributor
timestamp: March 09, 2024, 12:34:29 am
content: You said that you repaired the power supply? I may be possible that you might be getting the right amount of voltage but not enough current so the unit cycles. This can happen on computers if the power supply is to small. Can you bypass the DMX8000 screen to feed an external monitor with its own power. Don't know what external ports are available on the unit. Is there a video out you could use.We want to eliminate a power issue first . Then move on to a possible video processing issue.

author: ReedTriesToRepair
author_rank: Contributor
timestamp: March 09, 2024, 09:36:53 pm
content: Good ideas, thanks for your response @Jwillis - I don't believe it is related to the power supply though because 1 out of every 10 "tries" of plugging in the cables, I can get an image on the monitor. But I've haven't gotten it to work when I have the screen placed on the chassis yet, which is why I'm trying to determine which cable could be causing the issue.Also I don't believe it is a power supply issue because there is an external DC power-in plug and it behaves the same way whether I use mains or DC in.

author: Jwillis
author_rank: Super Contributor
timestamp: March 09, 2024, 10:21:28 pm
content: OK sounds good. It could very well be just a broken wire in one of the cables. Broken wires in cable can cause intermittent issues for sure. Many times it can be the connectors . Pin contacts can become loose. It only takes a small amount of movement to cause loose contacts to break connection.
LCD screen no signal no short found bad signal processor? - Page 1
Forum section: electronics / repair

author: ESXi
author_rank: Regular Contributor
timestamp: July 14, 2021, 11:42:10 pm
content: Hi,I was debugging this dead Ilyama 24'' capacitive touch screen with 1080p which was nice to save.Thing goes on black-light goes on shortly I see a disturbed image / noise artifacts then it goes back into sleep mode "no signal" blue led on system board stanby signal sent to PSU it detected the board trough the VGA connection(no strange hw flags), that was all.Two realtek chips1xSignal processor RTD2555LH1xMCU RTD2120L with external SOIC8 eepromIt seems like it does not detect a signal and turns off right away, tried to power it with a known good power supply (injected 5v), same behavior when I force the MCU to stay on same behaviour. Does the MCU/Signal processor communicate to the LCD screen board that also is responsible for the black-light, and further signal processing on the LCD controller baord that connects to the LCD screen itself?My guesses communication between screen board and signal processor fails, failed part? I checked one chip was getting a bit hot but it's a small QFN chip not sure if this can be the guy if even this guy is bad the board should not go in sleep mode again because of signal or the eeprom is corrupted somehow? Can't really find a schematic that looks even close to something and this is not a easy one it seems.I could retrofit a knock off board it in but that's not fun..
LCD spots repair? - Page 1
Forum section: electronics / repair

author: e-pirate
author_rank: Regular Contributor
timestamp: September 11, 2024, 08:53:08 pm
content: Hi folks!I've just unboxed my decade old Ohaus Traveler bench weight and was surprised by this strange black spots in the left corner of the LCD screen.The weight was always stored in it's original box and never damaged. The origin of this spots is unknown. Looks like an leakage maybe?Even this spots don't affect reading of the screen they annoy personally me.Is there is some way to fix this maybe? I don't think I will be able to get a replacement LCD for this unit.

author: inse
author_rank: Super Contributor
timestamp: September 11, 2024, 09:00:54 pm
content: As far as I know these „dendrites“ come from leaking seal between the two glass layers as they always grow from the sides as I observed.Unfortunately no cure available and defects will grow over time.

author: Gyro
author_rank: Super Contributor
timestamp: September 11, 2024, 09:13:50 pm
content: A recent thread...https://www.eevblog.com/forum/chat/weird-squiggle-on-20x4-lcd/

author: e-pirate
author_rank: Regular Contributor
timestamp: September 11, 2024, 10:25:47 pm
content: Thank you guys. I will move to that thread as more people involved there.

author: coromonadalix
author_rank: Super Contributor
timestamp: September 12, 2024, 01:32:07 am
content: @inse gave a response, and sadly it is not reversible
LCD TV chipsets and diag ports? - Page 1
Forum section: electronics / repair

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: November 12, 2023, 05:51:59 pm
content: Not really a specific repair question about a particular monitor.But I've been trying to find a way to identify LCD TV/monitor combos from the NTSC->HD transition era that would support 15KHz RGB directly.I figure people into repair would have deep knowledge about this.I know there's a list of 15KHz monitors, but there are so many brands out there at Goodwill stores that are not on the list.So here are my musings1) Is there a list of LCD TV chipsets and what brands used what? So I can figure out which one allowed 15KHz RGB.2) Some TVs seem to have a serial diagnostic service port (I guess?), is there a common standard to expect? Like can I use a FT232 and a terminal and try to talk to the TV before buying it?3) I bought a simple and cheap VGA test signal generator, I am too lazy to make my own (although I imagine it's not hard to bit-bang a RGB test pattern on a bottom-of-the-line PIC). But it doesn't do 15KHz CGA/RGB whatever. Anyone got a nice cheap CGA test generator? Like:https://www.ebay.ca/itm/2645420325584) Is there a way to distinguish CCFL from LED backlight quickly? Sometimes there's a "warning: mercury" sticker on the monitor, but not always.5) What is RGB/DTV? Nothing useful from googling...For example, I saw this Daytek DK-191, the connections really spoke to me. A C64 on the s-video, and a 128 on the RGB, you see?I want to avoid buying all this crap on a whim only to find out at home it doesn't do 15KHz RGB.And no, none of this makes any sense, I know... Vintage computing!

author: fzabkar
author_rank: Super Contributor
timestamp: November 12, 2023, 06:16:25 pm
content: Dump the EDID info from the VGA and HDMI ports and decode it. The monitor doesn't even need to be powered up to do this.You could hook up a laptop to the monitor and allow it to detect and store the EDID in the registry. You could then examine the Windows registry, export the EDID and analyse it with an appropriate tool.The EDID for my monitor is here:HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Enum\DISPLAY\AOCA781\1&8713bca&0&UID0\Device ParametersThis is the data:Code:"EDID"=hex:00,ff,ff,ff,ff,ff,ff,00,05,e3,81,a7,b8,8a,00,00,16,0e,01,03,68,22,\1b,78,2a,a6,9c,a1,5a,4b,98,24,16,4c,57,bf,ef,00,81,80,01,01,01,01,01,01,01,\01,01,01,01,01,01,01,30,2a,00,98,51,00,2a,40,30,70,13,00,78,2d,11,00,00,1e,\00,00,00,ff,00,30,38,30,34,35,4a,41,30,33,35,35,31,32,00,00,00,fd,00,37,4b,\1e,53,0e,00,0a,20,20,20,20,20,20,00,00,00,fc,00,4c,4d,37,32,30,2f,4c,4d,37,\32,30,41,0a,00,fa

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: November 12, 2023, 10:10:31 pm
content: Indeed! I'll read up on EDID.
LCD TV Question - Page 1
Forum section: electronics / repair

author: jheatac
author_rank: Regular Contributor
timestamp: December 12, 2024, 04:22:26 am
content: Good evening.I picked up a free 60+inch Samsung with failed back lights.I replaced the backlights without incident and it is an acceptable TV for the $38 I have invested.My question... After repair, there is a single row about 3" from the bottom and a single column about 2" from the right that I believe has a single color not responding - possibly yellow. There are times it is noticeable and times you can't find them depending on the image/color of the screen.Is this a damaged LCD (possibly from removing it and it flexing?)Is this a damaged or improperly seated ribbon cable for the LCD as I had them apart as well.I doubt it, but is it a video driver problem?I'm just trying to learn what went wrong so I don't repeat it in the future.Thanks!

author: u666sa
author_rank: Frequent Contributor
timestamp: December 12, 2024, 05:41:34 am
content: It's nothing you can fix.It is problem where the ribbon attaches to the screen itself, which you can not solder.That in turn is most likely caused by bad LCD.This problem can be fixed by pushing that ribbon around, perhaps propping it with a piece of folded paper. Other times the problem might go away by itself when display warms up. But at the end of the day there is nothing you can do.NOTHING.

author: jheatac
author_rank: Regular Contributor
timestamp: December 16, 2024, 02:24:39 am
content: Thanks for the response.Is this connection/ribbon cable exceptionally sensitive? I've messed with plenty of cables over the years, but is this a situation I need to spend extra care or was it likely just a failure unrelated to me moving things around?

author: Shock
author_rank: Super Contributor
timestamp: December 17, 2024, 02:56:59 am
content: The lcd ribbon bonds sensitive especially to pulling, strain, tearing.The adhesive can fail in may ways, poor handling or cleaning using solvents can run down into the bezel and contacts. Age, heat and model defects can also be a source of the issue.Generally pressing on the contact bonds lightly to see if a pressure bodge can be applied is lower risk than the disassembly and poor handling during so itself.Commercially bonds can be redone, but its labor intensive and requires expensive equipment.
LCR Meter DE-5000 Repair Help and Opinions Needed. - Page 1
Forum section: electronics / repair

author: Jorge4563
author_rank: Newbie
timestamp: April 07, 2020, 12:12:12 pm
content: My DE-5000 LCR meter failed while measuring a 2200 uF capacitor. Inside nothing smells or seems damaged. I have a multi-meter that I can use if needed.This is the behavior: Whenever the I connect a component to measure the AUTO feature kicks in and the meter acts confused and does not recognize what is being tested, constantly switches around. In the manual mode it does not read either. The meter is about 2 years old and has barely any use.Any help would be greatly appreciated.Along with my multi-meter and school lab equipment it was of great help.

author: kripton2035
author_rank: Super Contributor
timestamp: April 07, 2020, 01:38:14 pm
content: what probe do you use ? do you have another probe (crocodile versus tweezers) that you could test with ?

author: BravoV
author_rank: Super Contributor
timestamp: April 07, 2020, 01:44:07 pm
content: Have you tried at 100 or 120 Hz ?

author: Dr. Frank
author_rank: Super Contributor
timestamp: April 07, 2020, 01:52:03 pm
content: Impossible to make an analysis this way.Before you measured the 2200µF, did you make sure to discharge it?The chipset obviously is not protected well against over voltage, and is probably irreversibly damaged in such cases, if I remember some statements correctly.Frank

author: Jorge4563
author_rank: Newbie
timestamp: April 08, 2020, 11:14:37 am
content: I used the crocodile probes.

author: Jorge4563
author_rank: Newbie
timestamp: April 08, 2020, 11:16:35 am
content: I am going to try the different probes to see if it makes a difference.

author: Jorge4563
author_rank: Newbie
timestamp: April 08, 2020, 11:17:52 am
content: I have tried different frequencies and the issue is still present.

author: Jorge4563
author_rank: Newbie
timestamp: April 08, 2020, 11:20:59 am
content: Quote from: Dr. Frank on April 07, 2020, 01:52:03 pm

author: Jorge4563
author_rank: Newbie
timestamp: April 08, 2020, 11:22:48 am
content: I want to thank everyone for the help. I will report any changes.
LCR-T7 tester always detecting a battery - Page 1
Forum section: electronics / repair

author: bruno.gonc
author_rank: Newbie
timestamp: August 17, 2024, 01:32:08 pm
content: Hello, i searched on the forum and the internet and couldnt find anything about this problem. Normally the problems are about device not turning on or i also found a video on youtube with something similar where the device always detects a cell.Basically the background to it, i was testing a 10v capacitor and it tester just fine but i always run the test 2 or 3 times to be more accurate. At first it was fine, but when i run the 2 or 3 test this behavior started to appear. It always shows the same thing and even if there is no component to measure.Could someone give me hints about what might be the problem before i start opening up to check tue inside?At first i thought it may be a low battery notice or something, but i put it to charge and it is now fully charged but still same problem. It is also no possible to calibre since it always detects a battery whenever i press the test button. Below is a picture

author: madires
author_rank: Super Contributor
timestamp: August 17, 2024, 02:43:18 pm
content: We have several forum threads about that common problem. Usually it's caused by an electrolytic cap which was not discharged before testing. If you're lucky only the SRV05-4 and 6.8V TVS (weak input protection) are bad. Remove both and try again. If the problem persists then some pins of the MCU are toasted (a genuine ATmega can be replaced and programmed with one of the original OSHW firmwares).
LCR-TC2 multimeter - Page 1
Forum section: electronics / repair

author: kukulama
author_rank: Newbie
timestamp: September 06, 2021, 02:40:17 pm
content: Hello, I have recently bought a this great multimeter, it is almost identical to the one described here:https://www.eevblog.com/forum/testgear/tc1-lcr-meter-transistor-tester-fix/It is really useful and helpful, but has one extremely annoying property, when I measure some component it shuts down after up to 25 seconds, I would like to disable this function entirely, the controlling chip of the function is shown in the post I shared, alongside with schematic of entire board, it is this one STC15L104W.If necessary I am willing to desolder the chip and replace it with external switches.Thank you very much.

author: bob91343
author_rank: Super Contributor
timestamp: September 07, 2021, 12:06:18 am
content: I think that's in the firmware so first you have to figure out how to program it, and then modify the code.

author: coromonadalix
author_rank: Super Contributor
timestamp: September 07, 2021, 02:44:48 am
content: Well you have to get an stc isp programmer, the software who goes with it and hope you can read it if its not read protectedor you have to do some bus sniffing if you see some data going out to the main mcu or simply an pull up or down......for a simple shut down / watch dog you may go a long routehttps://www.stcisp.com/STC-ISP_update_history.html
LD Systems Dave 8 PA system toroidal transformer - Page 1
Forum section: electronics / repair

author: helmut
author_rank: Newbie
timestamp: April 24, 2025, 08:46:39 am
content: Hi !I'm trying to troubleshoot my small PA System, which is a Dave8 Roadie 2.1 thing from LD Systems.Yesterday i tried to switch it on, nothing happened, i then checked the fuse in the IEC socket, blown. Replaced it, blown again.I took the whole thing apart and checked the obvious stuff and from there i realized something was wrong with the toroidal transformer that is connected to mains and provides 2x33.9v on the secondary side. It blows the primary fuse even without any load on the secondary.The two secondary windings read 1 ohm but the primary side is a few KohmsI don't understand how it cannot be either open or short but somewhere in the middle, is it a common failure mode ?I'm no transformer expert so maybe i'm missing somethingThanks in advance !

author: elektryk
author_rank: Regular Contributor
timestamp: April 24, 2025, 10:56:20 am
content: Open winding shouldn't blow the fuse, but there also may be short circuit between pri/sec or short circuit with PE somewhere.

author: Le_Bassiste
author_rank: Frequent Contributor
timestamp: April 24, 2025, 11:28:02 am
content: primary sides of mains transformers have inductances in the Henry-range (not mikro- or milli- Henries). some DMMs mess up the Ohms readings when "confronted" with such large inductances.

author: Phil1977
author_rank: Frequent Contributor
timestamp: April 24, 2025, 11:43:06 am
content: Be aware that these toroidal transformers can have quite significant inrush currents. Did you check the current rating and speed of the fuse?
LR38368 Datasheet needed (old SHARP LCD: V-HOLD missing) - Page 1
Forum section: electronics / repair

author: georgian
author_rank: Regular Contributor
timestamp: January 01, 2024, 02:33:43 pm
content: Hello,I wonder if anybody could help me with this problem.Here I have this old sharp LCD. It is working and I traced the CSYNC and RGB inputs. It is from an mini poker machine. I want to repurpose the LCD for an test rig (arcade PCBs repair).On the LCD PCB there is a footprint for H-HOLD but now potentiometer. The traces are connected to the LR38368 IC. There is no other marking for an V-HOLD pot. The image won't sync verticaly with 320x240 resolution. Other Pots and test points are marked like this:VEE, VDD, VCC, H-POS, VG, H-HOLD, PD, VCO,VcAC, VcDC, B-SC, B-SB, R-SC, R-SB, CNT, R-SC, BRTLCD panel: LQ6RA01 720x240https://www.mikrocontroller.net/attachment/74838/Sharp_LCD_EL_1990.pdfhttps://gridcontroller.net/download/SHARP_interface_lcd_tft.pdfVideo of the vertical sync problem:https://youtube.com/shorts/nlJAYXgmmVAI did find some schmetics for the other IC IR3P89 but I see no use for it.https://monitor.espec.ws/files/schem13lcd10-10_237.pdfAny ideea how what can I do to get an V-HOLD on it and what should I do with the H-HOLD. I might need both of them.Any help is much appreciated.Thank you and happy new year!

author: georgian
author_rank: Regular Contributor
timestamp: January 01, 2024, 03:05:58 pm
content: I tried it now with an actual arcade PCB and it syncs just fine. That Raspberrry pi pico pattern generator might not have an true csync. I'll have to dig more.https://github.com/sharpie7/pico-pattern

author: georgian
author_rank: Regular Contributor
timestamp: January 01, 2024, 04:32:31 pm
content: Here I have traced the pinout and how the game PCB is driving the LCD.LCD LQ6RA01 pinout - schematic1, 2, 3, 5, 10 - NC4, 7 - +5V6, 8, 17, 18, 19, 20 - GND9 - BIAS12 - Brightness11 - CSYNC13 - RED14 - GREEN15 - BLUE
LD490DUN-THC4 - 'sales monitor' repair  - Page 1
Forum section: electronics / repair

author: darkspr1te
author_rank: Frequent Contributor
timestamp: June 03, 2025, 05:41:36 pm
content: So to cut a long story short a client of mine has a bunch of displays left over from events that were will to pay a premium to have a type of display at events and then toss, all the working ones were sold off ( of 36 purchased, 12 were still working at the end of 6 months) so the rest he kept and has melted a deal with me that i can repair 3 keep 1 , as i run a school in Africa this is gold for me,some free no border monitors. even a couple would be grand for our new stems room.so as mentioned these are sales/video wall style displays ment for 2x2/3x3 setups at events for display 2k on large display area.I've attached the common manuals for these panels as pdf below, i will discuss original driving panels, new panels in further posts.Things of note, panel is 2 channel/lane 8bit OR 10bit lvds based on pin 27(LCD SIDE) , High is 10bit, L/floating is 8bit according to official TCON board manual /service guide/training manual excepts can be found in the lcdrpairguide.com lg manuals.I have on order new boards to reuse these devices but not the original boards, i can only get them in orders of 1000 units, i need to repair maybe 15so my plan is to figure out to make another board work.darkspr1te
Leader 8064 Analog scope - Page 1
Forum section: electronics / repair

author: hitecelec
author_rank: Regular Contributor
timestamp: August 14, 2019, 02:42:01 pm
content: Hi Allfound q13, q 14 2sc1252 transistors defective in the final Y amp . looks very hard to locatecould anyone suggest a suitable replacement. , Will 2N5109 Work ?thanks in advanceAnand

author: benj38
author_rank: Frequent Contributor
timestamp: August 16, 2019, 08:04:57 pm
content: The 2N5109 does not look ideal, but there is an acceptable chance it will work .The main difference I see is slightly lower maximum voltage (you can analyze the circuit to see if this is going to be an issue), and lower gain (which may be a problem).I would give it a try and see if the scope works and can be calibrated.

author: tautech
author_rank: Super Contributor
timestamp: August 16, 2019, 10:39:11 pm
content: By definition CRO plate output amps are HV video amps and BF259 can be a good general purpose substitution although always cross reference datasheets.

author: hitecelec
author_rank: Regular Contributor
timestamp: August 17, 2019, 07:18:15 am
content: noted. thanks
Leader FG 1301 - Dirty switches - Page 1
Forum section: electronics / repair

author: Muett
author_rank: Newbie
timestamp: November 01, 2024, 01:04:17 pm
content: Just bought a Leader 1301 Function generator and was disappointed to find that all of the push button switches seem to be dirty. After trying multiple times I was able to finally get an occasional decent waveform on only a few the frequencies. The range buttons seem to be the worst while the frequency dial is clean, without any noise. The waveform buttons are also a problem but not as bad. My question is can I clean these with Deoxit D5? Or should I just return it (sold as “This is in good working order.”)?

author: Muett
author_rank: Newbie
timestamp: November 04, 2024, 12:40:35 am
content: Needles to say, Deoxit brought it back to life. Push button switches all work perfectly.
Leader LBO-315 oscilloscope problem - Page 1
Forum section: electronics / repair

author: hyrava
author_rank: Newbie
timestamp: May 31, 2019, 05:07:11 pm
content: I got Leader LBO-315 oscilloscope for free few days ago. Both channels seems to work, I can see traces and both channels react to signal.Problem is that every about 15-20 seconds power led turns off, screen goes blank and I can hear snapping sound somewhere inside. I haven't repaired any scopes before but I think problem is maybe in power supply (or high voltage arcing).I opened it and nothing looks visually burned, exploded or overheated. Does anybody have service manual or schematics to that scope? I tried to google but didn't find them.I apologise my bad English, I live in Finland and English is my third language.

author: wattsjake
author_rank: Contributor
timestamp: July 14, 2019, 01:03:12 am
content: Try turning on the oscilloscope with the cover off. You'll be fine as long as you don't touch the CRT or anything inside of the oscilloscope. Try and verify where the pop is coming from.Are there any other issues that the oscilloscope has? What happens on the screen when it pops? I'll try and look for schematics for it. Do you have any other information about the oscilloscope. Name, serial number, manufacturer, date of manufacture.

author: cvanc
author_rank: Frequent Contributor
timestamp: July 14, 2019, 08:57:03 pm
content: Carefully run it with the covers off in a dark room - can you see a place where it is sparking?

author: hyrava
author_rank: Newbie
timestamp: July 17, 2019, 11:22:15 am
content: Okay, today morning I had some time to take off top and bottom covers. I put scope on its side so I could see both sides. I turned it on and everything was fine (power-led on, both traces visible, no strange noises...) until... After about one or two minutes I heard first snap. Snapping interval got shorter and shorter until it sounds like intermittent buzzer. And then I saw where it is sparking. It is sparking between CRT and two springs (see attached pic, red circle). What does this mean?When sparking, power led turns off and screen goes blank.As i mentioned in 1st post, manufacturer is Leader Electronics Corp. Japan, model LBO-315, serial 6010129. I don't know manufacturing date but it is last serviced by FinnMetric Oy in 30.6.1989.
Leader LBO-508 - Page 1
Forum section: electronics / repair

author: Johnhos
author_rank: Newbie
timestamp: May 26, 2020, 09:56:32 am
content: Hi everyoneI recently got a leader lbo-508 oscilloscopeThe scope doesn't show anything on the screenI have done some measurementsTp1 -15.12vTp2 15.11vTp3 197vTp4 297vI don't currently have a meter that it rated high enough for tp5Tp3 and tp4 are a bit low I think this is due to C115 which has started to leakD116 and D117 have cracks on them and measure open circuit (with my multimeter)I am planning on replacing D116, D117 and C115Advice and/or recommendations please

author: BreakingOhmsLaw
author_rank: Frequent Contributor
timestamp: May 26, 2020, 01:34:39 pm
content: Get the Service manual here and follow the trouble shooting guide on page 18:https://www.opweb.de/deutsch/firma/Leader/LBO-508
Leader LBO-514A Chanel 1 problem - Page 1
Forum section: electronics / repair

author: georgian
author_rank: Regular Contributor
timestamp: March 26, 2020, 11:19:43 pm
content: Hello guys,Could someome help me to fix my very old oscilloscope?The Chanel1 lokk like dose't like very low voltages.I have a ramp signal that gose from 0V to 2.56V (Atmega32 with AD557 DAC)The Chanel 2 seams to work just fine but the Chanel 1 dosen't show the ramp as it should.I do have some electronic skills and an original manual with schematics from this oscilloscope.See the attached pictures for a clear details. Thank you.

author: georgian
author_rank: Regular Contributor
timestamp: March 26, 2020, 11:20:16 pm
content: Chanel 2

author: rmserroni
author_rank: Newbie
timestamp: March 27, 2020, 12:37:45 am
content: Okay, if you have the manual it is easier to check the attenual resistors at the input of the channel, you can inject a signal and compare between channels 1/2 in which component the signal is different, this component is defective.good luck

author: georgian
author_rank: Regular Contributor
timestamp: March 27, 2020, 09:43:56 am
content: Could you help me indentify this resistor? Is it one ofe this 3?

author: georgian
author_rank: Regular Contributor
timestamp: March 27, 2020, 10:32:17 am
content: After readinghttps://www.eevblog.com/forum/repair/leader-lbo-514a-strange-tail-on-square-wave/50/post on the forum I realized I have the same problem. I turned the VC1201 10pF capacitor all the way and it solved the problem.Thank you,Georgian Borca
Leader LG-1301 service manual needed - Page 1
Forum section: electronics / repair

author: electr_peter
author_rank: Unknown
timestamp: January 04, 2015, 07:55:47 pm
content: I am looking for Leader LG1301 function generator service manual to do general checks and adjustments.I have Leader LG-1311/LFG-1300/LFG-1300s service manuals from Leader service dep. (they do not have LG-1301 ser. man.) and other sources. LG-1311/LFG-1300/LFG-1300s are similar units to LG-1301, but not identical.If forum members have a service manual/schematic for Leader LG-1301 they could share, that would be great.

author: Gertjan
author_rank: Frequent Contributor
timestamp: January 05, 2015, 07:28:27 pm
content: PM sent

author: electr_peter
author_rank: Unknown
timestamp: January 20, 2015, 11:40:14 am
content: Still looking for a LG-1301 service manual.

author: sisfenix
author_rank: Newbie
timestamp: November 16, 2019, 10:12:52 pm
content: Quote from: electr_peter on January 20, 2015, 11:40:14 amelectr_peter, did you found the service manual?

author: electr_peter
author_rank: Unknown
timestamp: December 11, 2019, 09:37:45 pm
content: I found manuals for instruments with similar numbers which were very helpful. Device is still going strong after adjustments.

author: MonarkeIV
author_rank: Contributor
timestamp: February 03, 2020, 11:13:30 pm
content: If anyone else needs the exact service (LG1301 & LG1311) manuals, I have them both direct from Leader.

author: ferdieCX
author_rank: Regular Contributor
timestamp: February 03, 2020, 11:45:18 pm
content: Hi, I would like to have the service manual for the Leader LFG-1300. The plain model, not the "s" version.Does anyone have it ?

author: Calibrator
author_rank: Newbie
timestamp: March 09, 2025, 05:39:37 am
content: Hi, I would like to have the service manual for the Leader lg 1311 for repair.Thank you very much.
Leader LG3236 - No output over 100dBu - Unidentifiable SMD Part 1. - Page 1
Forum section: electronics / repair

author: ratlordfx
author_rank: Newbie
timestamp: August 12, 2021, 12:26:52 pm
content: Hi there,I recently bought an LG3236 off of ebay, and everything worked fine except for the output signal dropping as soon as I hit 101dBu, right when the relay kicks in. I had it open to clean all the controls, so I figured I would dive deeper into the RF output section. I opened up the shielded enclosure, and traced the signal back from the output. I noticed that when the signal hits 101dBu, it gets switched over from a bypass bus line to run thru some amplifier circuitry. I also found that the signal drops out after reaching U1, a small round 4-pin smd labelled "1." I measured this part and it has a very low resistance, but I cannot find any info about it.Can anybody help me identify this part? I also suspected that the rf amplifier RF2317 is bad, but I'm not sure.Any help is much appreciatedThanks,ratlord
Leader LMV-186A channel 2 not working - Page 1
Forum section: electronics / repair

author: Msw
author_rank: Newbie
timestamp: May 20, 2023, 05:13:51 am
content: HiThis is my first post here. I recently got a Leader LMV-186A that seems to be in good shape.The channel 1 meter is working correctly, but i dont get channel 2 to respond to input signals.I did zero the needle on channel 1, but did not manage to zero the channel 2 needle. Channel 2 do not adjust down to zero.Channel 2 is not responding to the input signal in either seperate mode or in in1/in2 to ch2 mode. But in in1/in2 to ch2 mode the range the range knob is working on channel 2. But still only channel 1 meter responding.How would you start to find the fault on this?

author: Msw
author_rank: Newbie
timestamp: May 20, 2023, 05:20:42 am
content: Input signal on Channel 2.

author: Andy Watson
author_rank: Super Contributor
timestamp: May 20, 2023, 11:53:03 am
content: Quote from: Msw on May 20, 2023, 05:13:51 amI always start by trying to locate a service manual with the schematic:https://bama.edebris.com/manuals/leader/lmv186ab/Not sure if the "B" suffix is significant - you will have to decide that.Then remove the covers and inspect, very closely for broken wires/connections, poor solder joints and dodgy looking components - escpecially old electrolytic capacitors. What happens next depends on what other test equipment you have available.

author: coromonadalix
author_rank: Super Contributor
timestamp: May 20, 2023, 02:27:20 pm
content: hum would the input switch need to be moved to ch2 / right position ? mmmm not so sure ... does it put the ch2 in parallelAnyway check the supply lines first as usual you have the 18vdc ones and they get dropped to 15 vdc further downabd maybe wobble the switch left and right a few times / oxydation ??

author: Runco990
author_rank: Frequent Contributor
timestamp: May 20, 2023, 05:13:23 pm
content: Did you "zero" the meters with the power OFF? Also breathe on the front to dissipate any static charge. I had one of these and the needles would repel each other. The front switch should have some deoxit, and don't forget the rear grounding switch.Also, I have noticed that the needles won't zero on the low settings, the meter is picking up some hum in the environment.These things rarely ever break. It's a solid meter, so eliminate that first. But the switches DO get tarnished.
Leader LTC-905 curve tracer issue - Page 1
Forum section: electronics / repair

author: RichardM
author_rank: Frequent Contributor
timestamp: January 13, 2024, 08:39:19 pm
content: Hi,I have one f these curve tracers and it has been great to check that transistors are functioning but it appears to estimate low values of hfe. I have built my own curve tracer to use as a comparison as well using an old analog Sanwa transistor tester. My home built tester and the Sanwa compare well for the same test levels but the Leader tester is always low?The leader does have an external bias input and if I use that for the base current it compares well with the other 2 testers. I have adjusted the step generator and it looks fine with 0.5V steps up to 3.5V so I am puzzled. It appears when the step generator is loaded through the range resistors, the base current and thus vertical deflection is incorrect.? The base current resistors all measure close to what is required also.I used my resistor substitution box in parallel with each of the range resistors to see what they would need to be to match the curves using the external bias input and they all need to be dropper to approx 85% of the specified values.Any suggestions on what may be happening is appreciated.Richard
Leader standard signal generator  3216 - Page 1
Forum section: electronics / repair

author: Proeletrotech
author_rank: Newbie
timestamp: January 20, 2023, 06:38:19 am
content: Hi guys, does anyone have the leader SSG 3216 service manual? I've got one with some problems, can anyone help me? Or if someone can help with internal PCB pictures will help too.
Leaf switch snapped, how would you repair? - Page 1
Forum section: electronics / repair

author: rthorntn
author_rank: Frequent Contributor
timestamp: May 28, 2020, 12:59:06 am
content: Hi,I have this old Monroe joystick and the one of the steel pieces that you attach the wiring to snapped.Of course it snapped right at the fibreboard so there is nothing protruding to solder a wire on to...These joysticks are rare, you can't buy replacement Monroe leaf switches for them anymore and so I want to repair it, I was thinking I could drill or cut away a small part of the fibreboard to expose some steels and solder to that, thoughts?Thanks.Richard

author: mathsquid
author_rank: Frequent Contributor
timestamp: May 28, 2020, 01:52:11 am
content: Could you solder a wire onto the other side of the leaf switch, near the fiberboard?

author: m3vuv
author_rank: Super Contributor
timestamp: May 28, 2020, 03:24:16 am
content: i cant belive someone is actualy asking this,! if you have half a brain i suggest you start using it ffs!

author: WattsThat
author_rank: Frequent Contributor
timestamp: May 28, 2020, 04:22:02 am
content: The last thing I would do would be attempt to solder to the bottom leaf.If the stack is under tension, and I would expect it is, as in screwed together, I would place a piece of .010 (.25mm) brass stock, cut to the width (with a hole to solder to) under the broken pice and re-torque the stack. Solder connection to the brass piece. Done. Next issue.

author: pickle9000
author_rank: Super Contributor
timestamp: May 28, 2020, 04:50:00 am
content: Solder a wire to the spring as it exits the block. If you think that will ruin it find a bit of brass strip and make a connector that will slide over the spring. Again keep it close to the block o minimize movement.

author: rthorntn
author_rank: Frequent Contributor
timestamp: May 28, 2020, 04:53:14 am
content: Thanks WattsThat, this is a great idea, in saying that, the stack is sort of riveted (see attached), I have a very thin copper shim and I can't slide it in there and I'm not sure I can get it apart, maybe I can cut a tiny bit of the fiberboard out and glue the copper shim to the fiberboard (making sure I get no glue between the leaf and the shim).Not sure on the state of the tension as its 40yo and each of the four switches are acting a bit different to each other.

author: edpalmer42
author_rank: Super Contributor
timestamp: May 28, 2020, 05:19:02 am
content: Quote from: m3vuv on May 28, 2020, 03:24:16 amhttps://www.eevblog.com/forum/chat/are-we-becoming-old-cranky-scrooges-in-these-forums/

author: jh15
author_rank: Frequent Contributor
timestamp: May 28, 2020, 04:15:37 pm
content: Looks exactly like pinball machine leaf switch. can get at pinball parts places.
Leaking Battery in My Small General Tools #1433 Pocket Caliper - Page 1
Forum section: electronics / repair

author: Smoky
author_rank: Frequent Contributor
timestamp: December 05, 2024, 11:29:25 pm
content: I use this caliper every day ever since I bought it four years ago. It is so handy to have around.Today, it started to act funny so it dawned on me to check the batteryThanks goodness, no appreciable damage done. I can see just where one tiny nick of plating was attackedAgain, remember to check/replace often or just remove the batteries if you're not using the device!

author: Muttley Snickers
author_rank: Unknown
timestamp: December 06, 2024, 01:03:52 am
content: Quote from: Smoky on December 05, 2024, 11:29:25 pmI had a similar event occur recently where my favourite and most trusted set of coolant proof calipers did not have such a favourable outcome. For over a decade and after every use I would meticulously place a small soft cloth over the display when placing the calipers back in their padded timber case, and never had any concerns about battery leakage with these calipers.A couple of months ago I went to use them and they were completely dead so I opened the battery cover to find the battery had corroded and badly damaged the pcb. After an extensive autopsy I concluded that the soft cloth I had placed over the display had inadvertently depressed the mm/ inch button permanently which inturn disabled the auto power off feature.I spent two entire days trying to repair them without success as the displayed measurements had become inconsistent after the mishap and no longer in agreement with my other sets of calipers. These particular calipers were more than just another tool in my workshop, I realised afterwards that I had in fact lost a dear and trusted work colleague.

author: Smoky
author_rank: Frequent Contributor
timestamp: December 06, 2024, 01:48:32 am
content: I literally spent the last hour going through every piece of my HVAC gear (scale, vacuum gauge, wireless thermometers, hygrometer, infrared stuff, etc, etc, etc) just in case I left batteries in them. I found one where I stored the batteries loose in the compartment. Even that ain't good!Anyway, I feel better now
lecroy 1855A - cosmetic damage but working, looking for spare - Page 1
Forum section: electronics / repair

author: worsthorse
author_rank: Super Contributor
timestamp: February 17, 2023, 08:16:08 pm
content: I picked up a Lecroy 1855A with the 200XC differential probes in good working order and some physical damage to the front panel: it looks like something very heavy gave it a glancing blow, breaking one of the button caps and gouging the front panel.Wondering if anyone here has a non-working version that I can harvest for mechanical parts? DM me here!Thanks,worsthorse
lecroy 204mxi ccomponent - Page 1
Forum section: electronics / repair

author: myhobo
author_rank: Regular Contributor
timestamp: January 03, 2020, 02:50:36 am
content: who can tell me what's this

author: DaJMasta
author_rank: Super Contributor
timestamp: January 03, 2020, 02:55:18 am
content: Is that right on the input? RF termination resistor for the input would be my guess.Could be a filter, I guess, but haven't seen that package (or lack thereof) for one before.

author: daqq
author_rank: Super Contributor
timestamp: January 03, 2020, 09:52:47 am
content: Looks like an SMD RF attenuator like these:http://www.barryind.com/chip_attenuators.html

author: DaJMasta
author_rank: Super Contributor
timestamp: January 04, 2020, 12:50:21 am
content: That certainly sounds right for the location and explains the three terminals! Gotta get the high voltage input range somehow.
LeCroy 44MXs-B oscilloscope HDD - Page 1
Forum section: electronics / repair

author: Radiosonde
author_rank: Contributor
timestamp: June 24, 2022, 09:55:55 pm
content: Hello,I recently bought a pretty used-up 44MXs-B oscilloscope that doesn’t boot, could someone who owns such a scope please contact me?I have a few questionsThank you very much.

author: LeBeep
author_rank: Newbie
timestamp: July 10, 2022, 02:22:09 am
content: You don't really need a backup of a LeCroy HDD. You can install everything from scratch.Change the motherboard CMOS battery while you're installing the new HDD.Install the OS - make sure you have 2 partitions for C:\ and D:\. I installed WinXP SP2Name D:\ "UserData"Install drivers for audio, video, ethernet, etc.Install the Lecroy capture drivers - this gets you a "Data Acquisition Device" in the Windows Device ManagerInstall XStreamDSOInstallerThe Calibration data is stored in EEPROM. It gets copied across to the D:\ drive once XStreamDSO launches.If you're having trouble finding drivers, try this:https://archive.org/details/UltimateWindowsDriverPackforVistaxp9895me20002003
Lecroy 454 wave surfer - Page 1
Forum section: electronics / repair

author: hitecelec
author_rank: Regular Contributor
timestamp: December 19, 2024, 11:56:10 am
content: Hi AllWindows xp ok. booting.application does not openattached screen shot

author: hitecelec
author_rank: Regular Contributor
timestamp: December 20, 2024, 07:53:14 am
content: Tried installing the application software and the drivers.After reinstallation and reboot, No success. Screen message " You are not authorised to run this Program "Looks like a hardware issue. Will open it up and check.Looks like PCI Bus is not recognising the lecroy acq board.

author: Dougmc
author_rank: Contributor
timestamp: December 21, 2024, 01:18:43 pm
content: There is a dedicated lecroy group on ioDoug

author: hitecelec
author_rank: Regular Contributor
timestamp: December 23, 2024, 09:34:17 am
content: Hello Dougthanks

author: Kurets
author_rank: Regular Contributor
timestamp: December 23, 2024, 12:18:37 pm
content: I had the same issue on my WR104Xi, the issue was due to dried out 1000uF/6.3V capacitors on the PC main board. This made supplies unstable enough for the FPGA PCI board to not interface correctly with the PC part.The telltale sign is missing the two beeps at boot.
Lecroy 510 Wavesurfer not powering on  - Page 1
Forum section: electronics / repair

author: hitecelec
author_rank: Regular Contributor
timestamp: May 23, 2025, 09:23:07 am
content: HiUnit doesn't power on. No relay Click , Fan doesn't workHave not opened the unit yet.Any schematics available for power supplyThanks in advance
Lecroy 6202 defect in probe recognition - Page 1
Forum section: electronics / repair

author: keesjalink
author_rank: Newbie
timestamp: May 13, 2024, 08:43:29 pm
content: Hi all, I am new to this forum, so please redirect me if I post this in the wrong group.I have a lecroy waverunner 6202 4 channel scope. All inputs work correctly when I attach a blockwave through a BNC cable and they work fine at 50 Ohms, at 1 MOhm DC as wel as AC settings of input coupling.However, if I attach the signal via the original lecroy probes, only channel 2 has a defect that I do not understand at all. The probes are 1x 500MHz types I think.In that case, channel 2 always sees a flatliner at 0 V. I confirmed that the probes are OK by swapping between channels and between different probes of the same type.So: all probes and channels are OK, except channel 2 which works well with BNC cable but flatliner with any of my probes,How can this be? the connection is merely a BNC, isn't it, how can it not see the probe signal that is clearly visible on the other channels? Any help much appreciated.Kees

author: m k
author_rank: Super Contributor
timestamp: May 19, 2024, 04:59:17 pm
content: Do you have BNC gender changers?Maybe it's a mechanical thing.

author: macboy
author_rank: Super Contributor
timestamp: May 20, 2024, 12:25:03 pm
content: Make sure channel 2 is not set to 50 ohms input impedance. That is one thing that would definitely cause this symptom.