hybridfree/eevblog-posts huggingface dataset:
Jamo sub 300 amp board repair - Page 1
Forum section: electronics / repair

author: N1TRO
author_rank: Newbie
timestamp: October 21, 2015, 10:13:23 am
content: Hi,I have a Jamo Sub 300 here that I bought off a friend for $20 due to it not working.I have taken it apart and I have heard from research that the brown goop goes conductive and causes problems. There are also a few suspect caps and the yellow 104k resistor looks to be burnt or something. I would like some opinions from those more advanced than me on what they think is wrong as this is my first attempt at a repair. Any thoughts are appreciated and if needed I can do some measurements for you. I have checked the fuse and it is fine but I don't fancy turning it on. I will also replace all the electrolytics.Here are some pictures:Thanks.

author: singapol
author_rank: Frequent Contributor
timestamp: October 21, 2015, 06:21:12 pm
content: Nothing out of the ordinary from the pictures. Do some resistance measurements first for shorts but make sure you discharge the caps with a 1K ohm 5 watt resistor or better yet a 10 watter. Check the output power transistors at oppoisite sides of the heatsink and the driver transistors. Then the caps. Test first before any cap replacement. it may not be necessary. If all checks out now time to power up and measure the power supply voltages. There should be plus and minus voltages. I don't think the glues are conductive.

author: station240
author_rank: Unknown
timestamp: October 21, 2015, 08:41:25 pm
content: The glue certain is a massive problem, and for this device in particular.see:http://forums.whirlpool.net.au/archive/1889470Carefully clean the brown glue from the main filter caps, bridge rectifier, 240/120V selection (pic 2)Then the same for the power diodes and filter caps on the other side (pic 5)You may need to unsolder these capacitors to check for corrosion underneath.measure the resistors you mentioned with a multimeter, to check the values against the colour bands.

author: Joule Thief
author_rank: Regular Contributor
timestamp: October 22, 2015, 08:57:08 am
content: Quote from: N1TRO on October 21, 2015, 10:13:23 amThe leads on the 160K resistor look a little suspicious, and maybe a cold solder joint on the resistor above that one (470 ohm?).

author: singapol
author_rank: Frequent Contributor
timestamp: October 22, 2015, 10:13:28 am
content: One end of 160k ohm seems to be corroded and touching the trace below? The other resistor should be 470 ohm.

author: N1TRO
author_rank: Newbie
timestamp: November 08, 2015, 07:40:50 am
content: thank you all for your advice, it has confirmed more or less what i initially thought. One thing that has me confused is as to whether the yellow passives are resistor or capacitors, the resistance is all over and i though they could be x/y caps but the capacitance is only brief. The other thing i wanted to ask is what the blue passives are. I assume they are ceramic or mica caps. Thanks.

author: N1TRO
author_rank: Newbie
timestamp: November 08, 2015, 07:50:52 am
content: ok so im pretty sure that the blue passives are emi/rmi suppression x/y caps and the yellow devices are caps.
need help in repair\testing of this smps  - Page 1
Forum section: electronics / repair

author: stoica adrian
author_rank: Contributor
timestamp: November 07, 2015, 05:50:11 pm
content: I have this telekom smps. When i power it up, the line fuse blows. I use an autotransformer for a slow power it ( is the same problem without autotransformer). When my voltage is at around 110V, i can see how the internal relay from the smps are closing, and then a large current is absorbing frome the line blowing the fuse of the line smps ( 4-6A at the autotransformer ampermeter) . The question is .. what can i use to limit the current, there is something special fore a start up of this kind of telecom power supply?, because i appear that this kind of smps are used along a controller, and ja, i dont have that controller.I dont have a lot of experience in repair this kind of smps. i am electronics technician at my background. Thank you all for the supportObs- i measure all the components, i don't find a problem with them

author: tautech
author_rank: Super Contributor
timestamp: November 08, 2015, 07:33:40 am
content: I'm no expert with SMPS but there are few basic steps that can help with trouble shooting.No particular order:1. Identify controller and find datasheets, often "typical application" examples are closely copied by manufacturers in their designs.2. Power on with aDim Bulb testerin series with the mains supply, it will limit inrush current are preserve fuses. Google it.You set the supply current value by selection of the bulb wattage.3. Power only the controller from a bench PSU and check for the correct waveforms without risk from mains voltages.Simple failures you should check for:Resistor/s, or chain of, that supply current to the controller from rectified mains for startup.Local bulk cap to the controller, ~20-50 uF, gone high ESR or drifted in value.Flyback diode that supplies controller operating current for continious operation.UVLO values
st micro l387a - Page 1
Forum section: electronics / repair

author: merser
author_rank: Contributor
timestamp: November 07, 2015, 03:51:57 am
content: I have this oven controller that has failed and after testing voltages and various components without finding issue heated it up in another oven and tried and it worked. Once it cooled down it went basically dead again except for clicking noise through piezzo and faint flashes on digits of display.So I got my butane solder pencil and heated various components one at a time until I discovered the l387a when heated would allow the board to come to life.The voltage in and out is ok (+12 and +5) so I can only think the issue is in the reset circuit.Does anyone know where I can get one fairly quickly or a suitable substitute. It appears to be an obsolete part.

author: tec5c
author_rank: Frequent Contributor
timestamp: November 07, 2015, 05:11:41 am
content: http://www.ebay.com/itm/5PCS-L387A-VERY-LOW-DROP-5V-REGULATOR-WITH-RESET-TO220-5-/221326983736

author: merser
author_rank: Contributor
timestamp: November 08, 2015, 05:30:23 am
content: Thanks. There are a few on ebay but none local. I guess I will have to be patient.
Magellan GPS 315 teardown/repair - Page 1
Forum section: electronics / repair

author: tk175672
author_rank: Newbie
timestamp: November 06, 2015, 10:39:17 pm
content: Sorry for any grammer/spelling mistakes as I am only a teenager and I am rushing to write this in between school.I recently purchased a GPS 315 from a ham radio festival for about 1USB. The man said it worked as he used it for APRS for years. I got it home, powered it up and all i got was a screen with a single black line on each side. My first test was to see if it worked at all. It responds to all menu inputs correctly (as judged by beeps) and the lcd back-light settings work fine. I updated the firmware as well as downloaded GPS locations (none to download as power had been gone for a year or so) but it at least worked. So i knew it wasn't software it had to be hardware.So i opened up the case and found that it is decently simple inside. A mixture of off the shelf components (a simple max boost converter and a few OP AMPS) and custom rolled chips (magellan CPU and another smaller chip) and higher end stuff (volatile memory for storage and another chip for firmware) Even had fun probing parts of it with my custom scope. (input impedance is only 5k ohm or so. I need to be careful i don't overload circuits with it.)So I took a look at the screen. Bare silicon die controller and the funky flat ribbon connector (like they use on calculators. just held down by glue.) and i thought "A Ha that must be it.". So i started probing and one pin wasn't connected properly. When i pressed it down the screen would "scan" as long as i pressed it down but when i let go it would freeze. I heated the connector and pressed it back down and now the screen mostly works. I get the "Alert" word at the top telling me it lost power and a few horizontal lines near the bottom but nothing else. Most of the messages/text near the top work fine but nothing near the bottom displays. but yet they aren't dead either as when i turn it on they display the "garmen" logo REALLY dim. If i push on the screen and then remove pressure it displays exactly what it should display (that weird thing with LCD's where if you press on them they invert colors) but it isn't mechanical as i have tested all the connections yet it isn't electrical as it will work when i press on the screen so i am afraid it is the LCD controller.Any advice as i don't really want to chuck it as it would be nice to learn to interface with a micro-controller. (as well as have a GPSalways wanted one)

author: Rasz
author_rank: Super Contributor
timestamp: November 07, 2015, 11:49:43 am
content: Quote from: tk175672 on November 06, 2015, 10:39:17 pmpictures

author: tk175672
author_rank: Newbie
timestamp: November 07, 2015, 12:43:36 pm
content: Wow for a 720p webcam it takes terrible pictures... I will have to upload better ones later but I don't have time now.
What's this component marked 'C2 GND 500405' on GTX graphics card? - Page 1
Forum section: electronics / repair

author: jgorsk
author_rank: Regular Contributor
timestamp: November 12, 2015, 11:17:43 am
content: Can someone help me to identify what this blown component is please?It's used on nvidia-geforce-gtx-titan-black graphics card, smd markingis 'C2 GND 500405'It's designator is Q3, it's next to the 2-pin white connector on top side of the cardhttp://images.bit-tech.net/content_images/2014/02/nvidia-geforce-gtx-titan-black-review/zotactb-9b.jpgIt's looks like a current sensor or a transistor.
motorola R2001D  no horizontal ....help plz - Page 1
Forum section: electronics / repair

author: Naim555
author_rank: Contributor
timestamp: November 04, 2015, 11:11:16 pm
content: when i plug my motorola r2001d i watch just a vertical trace (see picture ) when i select 'scope AC' i have just a spot in screene , i can move this spot in vertical position but no horizontal move when i move horizontal botton .i make the test the point TP1 TP4 TP5 TP6 for A2 modul :TP1 : nice signal (see pic)tp4 , tp5 : no signal (see pic )tp6 : nice signal (see pic )thaks and excuse for my bad english
Nexus 5 front cam socket brocken and gone forever - Page 1
Forum section: electronics / repair

author: fusionimage
author_rank: Contributor
timestamp: November 01, 2015, 07:02:32 am
content: this is what i found, while taking apart my phone to see what's wrong with the front camwhy?? just why?? and how?!

author: crispy_tofu
author_rank: Super Contributor
timestamp: November 01, 2015, 07:22:03 am
content: Did you rip the socket straight out?Sheared right off

author: SeanB
author_rank: Super Contributor
timestamp: November 01, 2015, 08:00:04 am
content: Dropped, and the mass of the camera module and socket ripped it off the PCB.

author: miguelvp
author_rank: Super Contributor
timestamp: November 01, 2015, 08:02:21 am
content: Maybe the right force at the right angle if you have dropped your phone?Edit: SeanB beat me to it.

author: tec5c
author_rank: Frequent Contributor
timestamp: November 01, 2015, 09:07:12 am
content: Apart from, ugh.... selfies, what else do you need the front cam on a mobile phone for anyway?

author: SeanB
author_rank: Super Contributor
timestamp: November 01, 2015, 09:54:53 am
content: Quote from: tec5c on November 01, 2015, 09:07:12 amFor the Narcissistic to do their hair, or on a more prosaic note to see if there is spinach stuck in your teeth.

author: crispy_tofu
author_rank: Super Contributor
timestamp: November 01, 2015, 10:10:55 am
content: 'There's something on your face'You can also use it for video calling

author: amyk
author_rank: Super Contributor
timestamp: November 01, 2015, 02:57:06 pm
content: It won't be an easy repair, but probably still could be done with careful manipulation under a microscope.

author: fusionimage
author_rank: Contributor
timestamp: November 01, 2015, 03:59:38 pm
content: i guess, it really happend while dropping it once.... unlikely but not impossiblefixing it is impossible. only some of the traces are left on the pcb. and just 2 or 3 of them are on the visible layer....and yep, i don't need it since i don't see the point in selfies

author: MatthewEveritt
author_rank: Unknown
timestamp: November 03, 2015, 12:55:47 pm
content: Quote from: tec5c on November 01, 2015, 09:07:12 amThey can be pretty useful to see the back of awkwardly placed racks, computers etc.

author: wraper
author_rank: Unknown
timestamp: November 03, 2015, 01:02:13 pm
content: Quote from: fusionimage on November 01, 2015, 03:59:38 pmFixing is possible (have done that) but takes a lot of time, needs microscope and a lot of tiny stuff soldering skill .

author: Deathwish
author_rank: Unknown
timestamp: November 03, 2015, 01:03:35 pm
content: Quote from: tec5c on November 01, 2015, 09:07:12 amskype or facetime
Repairing a LED driver from a 32" TV - Page 1
Forum section: electronics / repair

author: dr_p
author_rank: Frequent Contributor
timestamp: November 05, 2015, 11:53:28 pm
content: HiCan you guys please help me out?! I'm stuck.I'm trying to repair a 32" Philips LED TV that has no backlight. Everything else works.I took out the power supply, and when powered on it makes an intermittent zum-zum-zum.I uploaded a ZIP archive containing all the documentation - photos, schematic and also some oscilloscope captures.The ZIP file is here:http://we.tl/zJ2z0ayQVhI am using a grounded DS1054Z and using an isolating transformer for the board under test.The 400V supply is stable, caps are ok.I removed Q501 and IC500, both were short-circuit.I connected the ground clip to the probe tip, placed it over Transformer TR300 (that poweres the logic board) and it seems to be working. Also +12VCC present and stable.Next I placed the same loop over TR200, and I got this pulsing:Now I scoped the output capacitors of TR200 - C211 and C212 (before / after the inductor). Both look like this:Next I scoped the transformer's driver - Q204, for Source to Drain, i got his:Each "pulse" looks like this in detail:Then I looked at IC201 (all measurements reffereced to it's GND - pin 1).This is IC201 pin 1- pin7 (VDD)This is IC201 pin 1- pin2 (Feedback)This is IC201 pin 1- pin5 (Temperature?)This is IC201 pin 1- pin6 (Current Sense)This is IC201 pin 1- pin8 (Gate Driver Output)I also scoped the current sense resistor R212:Then the IC200 Optocoupler's diode:And D205 (TL431) Anode - Reference :I can't, for the life of me, make sense of this -why is it restarting?Can anyone please help?

author: Rasz
author_rank: Super Contributor
timestamp: November 06, 2015, 02:07:18 am
content: Quote from: dr_p on November 05, 2015, 11:53:28 pmdo you really expect people to download zip archive?

author: crispy_tofu
author_rank: Super Contributor
timestamp: November 06, 2015, 04:42:16 am
content: I can't help (sorry), but there's quite a lot of pertinent information in the zip archive...

author: tec5c
author_rank: Frequent Contributor
timestamp: November 06, 2015, 05:37:16 am
content: Quote from: crispy_tofu on November 06, 2015, 04:42:16 amYou mean impertinent...Too much irrelevant info.You found faulty components which you removed... and then you started probing with the unit on and can't make sense of what is happening? A pretty logical thing to do would be to test the surrounding circuitry of those shorted parts. Also, you didn't say if you had replaced them either.If you can't find anything else faulty, replace them, see if they blow, if so start testing again, if not then I downloaded a zip file for no reason.
Strange resistor code - Page 1
Forum section: electronics / repair

author: David Aurora
author_rank: Frequent Contributor
timestamp: November 03, 2015, 02:49:49 am
content: Just pulled a scorched resistor out of an amp I'm fixing and the code has me stumped. It's red/brown/gold/gold/violet.I *think* it might be a 0.2 ohm flameproof fusible resistor but I need a second brain to confirm that for me if possible. It's in a fan circuit and seems to have gone open circuit and been scorched, so that kind of adds up to me but I'm not certain.Thoughts?

author: tec5c
author_rank: Frequent Contributor
timestamp: November 03, 2015, 04:06:33 am
content: For what it's worth, I am pretty certain that you're correct in it being a 0.2 Ohm flameproof fusible resistor.First two bands being the digit, third band is multiplier, fourth band the tolerance, fifth is the quality band...Edit: Are you able to post a photo of it or is it too far gone to be of any help?

author: tautech
author_rank: Super Contributor
timestamp: November 03, 2015, 06:24:50 am
content: Recent thread that will help you:https://www.eevblog.com/forum/beginners/resistor-confusion/

author: David Aurora
author_rank: Frequent Contributor
timestamp: November 03, 2015, 06:50:28 am
content: Thanks guys, it's looking confirmed between that stuff and some circuit tracing I did to see what would make sense to be there. New ones are already on the way, gotta love free delivery from RS for a handful of 30 cent parts, haha
Component identification - Page 1
Forum section: electronics / repair

author: mattltm
author_rank: Newbie
timestamp: November 03, 2015, 08:48:16 pm
content: Hi all.Can anyone identify this part. It's marked VA9 (or maybe VA6?)? A bit of a long shot I know...

author: cinis
author_rank: Newbie
timestamp: November 03, 2015, 10:37:06 pm
content: I think it is a Single 2-input NAND gate 74LVC1G00

author: mattltm
author_rank: Newbie
timestamp: November 03, 2015, 10:52:10 pm
content: Thanks cinis.One of these then?http://uk.rs-online.com/web/p/standard-logic-gates/0510308/http://uk.rs-online.com/web/p/standard-logic-gates/6628679/http://uk.rs-online.com/web/p/standard-logic-gates/7705320/http://uk.rs-online.com/web/p/standard-logic-gates/7512771/It's part of an RC receiver that took a bit of a crash. Ripped the part clean off the pcb so I'm hoping I can pop a new one back on. May have to but a bodge wire in on one of the pins as it tool the solder pad off too!
Solar battery charger repair help - Page 1
Forum section: electronics / repair

author: sspj9
author_rank: Contributor
timestamp: October 25, 2015, 03:58:54 pm
content: Hi,I have a portable solar 5v output battery charger. I accidentally shorted out the output voltage (positive and negative together) .. Now it wont work ughh. What seems to have blown out pls? thanks!

author: Kopernik
author_rank: Contributor
timestamp: October 25, 2015, 04:01:39 pm
content: For a start you will need to open it..

author: sspj9
author_rank: Contributor
timestamp: October 25, 2015, 04:07:48 pm
content: I did...

author: steve207a
author_rank: Contributor
timestamp: October 31, 2015, 06:50:29 pm
content: Hi follow the 2 wire you shorted onto the board and look to see if they are attached to any components as sometimes ive found just a wire fuse wire soldered across 2 terminals which when blown is impossible to see as it just dissapears may be in your case or maybe not but worth looking at

author: NiHaoMike
author_rank: Super Contributor
timestamp: November 02, 2015, 07:32:51 am
content: Try briefly bridging B- to the outside of the USB socket to reset the overcurrent protection.
repeated heating of components - Page 1
Forum section: electronics / repair

author: R_G_B_
author_rank: Frequent Contributor
timestamp: November 01, 2015, 02:12:01 pm
content: I Am trying to repair a graphing multimeter.I located the problem down to the ASIC and CPU components not soldering to the board properly I keep having to solder them when I leave them to cool the fault returns and the board will not power up and the crystal oscillator will not run sometime intermittently when the voltage is being pulled down to 1.2V from 3V.Has anyone come across a problem where as as soon as the board cools down the components loose contact with the trace.And will repeated heating using a hot air station damage the components the maximum temperature I am using is 300 degree C.I have had the board running but when the board cools down back to square one.Can anyone help with this problem?ThanksR_G_B
Very dusty computer SMPS powersupply repair - Page 1
Forum section: electronics / repair

author: OldSchoolTechCorner
author_rank: Frequent Contributor
timestamp: November 02, 2015, 06:10:43 am
content: I normally don't repair these for people as not cost effective and have other projects I have to finish, but a friend took it to major electronic store to get a quote on repairing it and told me they were going to charge him around $500 bucks to repair it. So I decide to look at it rather then let him get ripped off. Only cost around $3 bucks in parts and about 1 hour of time, so not sure where they came up with the $500 dollar quote?Reason it more likely failed in the first place, as was just flashing yellow front panel LED's. This is why you also have to clean the inside, not just the outside. As barely no airflow and more likely what caused the capacitors to fail.Jump power supply on out of machine and notice rails were low and a lot of ripple, took apart and notice the bulging capacitors.Check with ESR meter and definitely they failed.I only replaced the defective capacitors for now as wanted to make sure no other bad components and make sure rest of computer was fine first, will replace them all later.Put back together as tested and no more excessive ripple and rails back to normalGive the machine a good cleaningWorks great, no more flashing lights

author: Vgkid
author_rank: Super Contributor
timestamp: November 02, 2015, 06:50:01 am
content: What brand are those capacitors?The PSU looks fairly old, even though it is a somewhat recent unit.

author: crispy_tofu
author_rank: Super Contributor
timestamp: November 02, 2015, 07:03:19 am
content: Looking at the pictures, at least it seems like Dell isn't using those horrible proprietary 24pin ATX connectors in this PC...I'm pretty sure Flextronics is a reputable PSU manufacturer, they make the Corsair AX and AXi range

author: OldSchoolTechCorner
author_rank: Frequent Contributor
timestamp: November 02, 2015, 07:27:02 am
content: Quote from: Vgkid on November 02, 2015, 06:50:01 amPSU is made by Flextronics and capacitors by Samxon. I don't blame the PSU, I blame the user for not cleaning the machine, pilot error on this one. The fan was completely clog up, so no airflow. I am shock it lasted as long as it did.
philips opened  and closes - Page 1
Forum section: electronics / repair

author: sdk.61
author_rank: Contributor
timestamp: October 30, 2015, 09:33:29 pm
content: hi Hi friends, I have my Philips LCD monitor (170S7FB/00) opening and closing (BY ITSELF closing and openingthanks

author: crispy_tofu
author_rank: Super Contributor
timestamp: October 30, 2015, 10:52:47 pm
content: Wait, what?

author: Little Brutus
author_rank: Unknown
timestamp: October 30, 2015, 11:16:18 pm
content: Bet he means it is turning on and off by itself.

author: dom0
author_rank: Super Contributor
timestamp: October 30, 2015, 11:20:21 pm
content: Are there no turkish electronics forums? Or did glorious R.T. Erdo?an ban those?

author: AwArD_RzD
author_rank: Regular Contributor
timestamp: October 30, 2015, 11:28:08 pm
content: Quote from: sdk.61 on October 30, 2015, 09:33:29 pmCheck the capacitor (discharge them before some have lethal voltage) , i had several lcd monitor/tv restored who had this problem, with time they dry and they can't keep the flow and start to flick the screen (on and off) some fast and other so slow you start to think if it's someone try to prank you with a remote.

author: sdk.61
author_rank: Contributor
timestamp: October 31, 2015, 06:27:18 am
content: I wonder what the breakdown isphilips lcd monitor
Crackling sound/noise from CyberPower PR1500LCD UPS - Page 1
Forum section: electronics / repair

author: sequoia
author_rank: Unknown
timestamp: October 28, 2015, 07:42:23 pm
content: CyberPower PR1500LCD UPS has recently developed annoying "crackling" noise. (Attached MP3 has sample of the sound)This doesn't sound to me as typical inductor/coil whine (?) Any ideas what this could be?Unit is powering punch of equipment currently and passes self-test fine, so I haven't been able to take a look inside, yet.Need to also check if this thing is still under warranty...although shipping might not be worth it as it weights over 50lb and I doubt warranty in US covers shipping (in EU/Australia it might be different story....)
Need photographic help repairing Voltcraft LPS-1403 lab PSU (Manison OEM)! - Page 1
Forum section: electronics / repair

author: MBY
author_rank: Regular Contributor
timestamp: October 27, 2015, 06:53:39 pm
content: I did a stupid thing and blow up one of my lab power supplies. It's a Voltcraft LPS-1403 (from Conrad):http://www.conrad.se/Laboratorieaggregat,-justerbar-VOLTCRAFT-LSP-1403-0-36-V%2fDC-1-x.htm?websale8=conrad-swe&pi=511632&ci=SHOP_AREA_17452_2110330(Conrads Swedish site)I know the unit is made by Manison so I expect that others may know the unit under different names and/or model numbers.My unit got a taste of mains AC on the DC output and several passives on a control board went up in smoke. I reckon it is fixable, if I obtain the values. So here is my suggestion: can anybody who have a unit maybe do some high res photographing or write down the values (of the resistors. I'm doing some guesswork on the SMD caps).Another user on the forum, hacklordsniper, did a teardown of the unit:https://www.eevblog.com/forum/reviews/voltcraft-lsp-1403-teardown/The board of interest is the smaller PCB mounted in the unit and the component side I'm interested about is facing outwards (visible in hacklordsniper's fifth photo), so the only thing needed is to take the cover of. It's very likely that other parts have been damaged, but the 0805 passives are the only components that cannot be identified (because smoke...).As said, the board are the smaller one and the interesting side is facing out under the hood on the left side. The components burnt are R4, R5, R6 and C4, C9, C10 and C11.And the lesson learned: Never test an UPS with a lab PSU instead of battery and have itconnected to mains! As if I didn't know that! Sometimes I'm just stupid (and no, the UPS didn't survive and is beyond economical repair).Strange thing, but the switching transistors, the power components, etc, seems fine and measures ok. Only the passives on the control board are damaged to the eye.
Tektronix TDS3032 not registering button presses - Page 1
Forum section: electronics / repair

author: KSP
author_rank: Regular Contributor
timestamp: October 29, 2015, 11:08:17 am
content: Hi allI had a job lot of tek scopes with various problems, mostly PSU issues, and I've whittled my way down to the last one. Now that the PSU is working in this one (TDS3032) I am presented with a new fault. It powers up just fine, even detects inputs and displays trace fine blah blah blah. Problem is the buttons are all totally locked up, cannot change anything. Not a single button or dial is doing anything (apart from on/off obviously).Works totally fine over the bus; programs up fine, changes ranges, measurement functions are fine, etc. but no manual use.Any ideas where I should even start with this?

author: voltsandjolts
author_rank: Unknown
timestamp: October 29, 2015, 07:10:55 pm
content: If you have another tds3k 2 channel scope in the job lot you could try swapping the front panel PCB.

author: tautech
author_rank: Super Contributor
timestamp: October 29, 2015, 07:15:14 pm
content: Can your share more info?Is the Front panel getting power?Reseated all connectors ?Do you have any of the others to swap out boards to test for functionality?Editvoltsandjolts thinks similar

author: KSP
author_rank: Regular Contributor
timestamp: October 29, 2015, 08:10:30 pm
content: Front panel seems to have power. Display comes up just fine, channel LEDs illuminate, running the self diagnostics and self cal over the bus does not flag up any issues. All connectors reseated.I do have others, the only issue is because I have already repaired those ones they have been recommissioned into use so I'd have to raise all the paperwork again to start stripping bits out. Perfectly doable though, I just wanted to know if anyone had any similar experiences. Removing the front panel requires a full disassembly, so I was hoping someone had a quicker fix
14.4V charger repair - Page 1
Forum section: electronics / repair

author: MadMan2021
author_rank: Newbie
timestamp: October 28, 2015, 08:11:05 pm
content: Greetings all,I've just been handed a 14.4V drill battery pack charger that needs to be repaired, simple circuit as you will see in the pictures below.Looks like a trace has blown and what I think looks like a resistor.Could one of you smart guys help me figure out what the component is which has blown in half.Any help is appreciated.Battery pack is a DRAPER 14.4V Battery Pack. It states for use with 3-5 hour charger.RegardsJordan

author: mikerj
author_rank: Super Contributor
timestamp: October 28, 2015, 09:54:48 pm
content: The broken looking component is a resistor, which is used to limit the current through the LED. Unfortunately it's value would have been encoded using coloured bands on the outside which have been burnt off.More importantly you are completely missing a high power resistor from the middle of the board (the empty blackened area), and without that that charger simply won't work at all. If you replace the big resistor with the correct value, the charger will work, but the LED won't. The LED is connected across the big resistor, so it only lights when charging current flows, so if you replace the big resistor and measure the voltage across it, we can work out a sensible value for the smaller resistor.

author: Seekonk
author_rank: Super Contributor
timestamp: October 28, 2015, 10:06:28 pm
content: It has a very crude charger and you could start with a 10 ohm 5-10W for the big resistor and 330 for the little one. For the little resistor to burn up the battery has to be shorted along with the LED now being dead. I can't imagine this whole drill set being nothing but junk when a battery needs to be replaced. This is nicad, right.

author: MadMan2021
author_rank: Newbie
timestamp: October 29, 2015, 02:39:40 pm
content: Quote from: mikerj on October 28, 2015, 09:54:48 pmThanks for your input, from what I was told there was nothing in the emptry slot in this middle which confused me also. I'll go back and ask him if he is sure nothing was in the casing.Ether way I'll get my hands on the resisters and solder them on see what i can do.What would be the best way to check if the battery is shorted ? Thank you

author: Kleinstein
author_rank: Super Contributor
timestamp: October 29, 2015, 04:49:28 pm
content: Th check the battery pack, one could charge it at low current (e.g. C/20 - something like 50-100 mA) for something like 5 hours, than load it at a similar current for somthing like 30 min (to get rid of the initially higher voltage) and than measure the voltage. It should be a little higher than the nominal 14.4 V (e.g. 14.7 V) - if its much lower one or more cells are likely dead (0 V or even reverserd). Even with 1 or 2 cells dead the pack may be still usuable, though at lower power.If you have acces to the individual cells its even easier.
GW Instek GDS-1052-U: Datalogging not working. Help? - Page 1
Forum section: electronics / repair

author: nikkoderic
author_rank: Contributor
timestamp: October 27, 2015, 12:40:53 pm
content: Hello eevblog community!I'm having an issue with the data logging feature of GW Instek GDS-1052-U Oscilloscope. In the manual it says,"The files saved in the LogXXXX directory are named DSXXXX.CSV, or DSXXXX.BMP for data or image files, respectively."The scope only creates folder for the data log session but without the csv file or even the bmp file inside.The hard copy feature of this scope seems to be working just fine so I don't think this problem has something to do with the usb or its formatting.I already emailed GW Instek but I'm hoping someone here knows about this and can help me now.

author: hexreader
author_rank: Frequent Contributor
timestamp: October 27, 2015, 04:57:36 pm
content: I just tried data-logging for the first time ever, using FAT32 formatted USB drive 4GB completely blank - default capture settings with cal signal on input A - seemed to work perfectly.Have you tried a different stick, freshly formatted to FAT32?What version of firmware do you have?Does the scope report saving to files every 2 seconds? (assuming that you set the default of 2 seconds)Wildly guessing here - but could it be that you are trying to save, faster than the scope can write files to USB? - try longer time between saves

author: nikkoderic
author_rank: Contributor
timestamp: October 28, 2015, 04:56:58 pm
content: Thanks for your response. I already know what's happening. It seems that my expectation of how datalogging should work in this scope is different from what it actually does. It requires that the signal should be trigger able and only then the scope will datalog the whole triggered waveform every some time. Maybe I'm the only one unaware of this.

author: hexreader
author_rank: Frequent Contributor
timestamp: October 28, 2015, 05:01:29 pm
content: QuoteYes, DSO takes regular samples. Much information is missed between samples. That is a big limitation of DSOs.That said - modern DSOs are awesome.... even the cheap ones... You just need to be aware of their limitations
Logitech Speaker system voltage leak - Page 1
Forum section: electronics / repair

author: N TYPE
author_rank: Regular Contributor
timestamp: October 26, 2015, 02:13:37 am
content: I have a Logitech z906 speaker system which was only 6 months old.While rearranging the system the other day I was feeling a tingle when I would touch the heat sink on the back of the amplifier.Put my meter on it and was reading 100vac to earthIm in australia we use 240v MEN systemThe device doesnt have an earth pin and shows double insulated symbol on the box.As tempted as I was to pull it apart and have a look inside i refrained from doing so and contacted the supplier for a replacement.Recieved my brand new replacement unit yesterday and decided to test it before setting it up.Lo and behold theres 100vac between the exposed metal and earth on this unit too, although this time I cant feel any 'tingle' when touching the exposed metal.What do you guys make of this.. is it some sort of ghost voltage? I could definately feel some current flowing while touching it though.. similar feeling to when you would touch the antenna port on some older TV sets..The unit is supposedly double insulated so this should not be possible, right?Logitech is a legit brand which surely must have gone through proper certification so I doubt the design is dodgey, however it is made in china so perhaps the switching transformer has been swapped out for a dodgey local one with poor isolation.. ?

author: samnmax
author_rank: Regular Contributor
timestamp: October 26, 2015, 03:40:00 pm
content: Usually the tingling sensation on an isolated device is caused by a Y capacitor between the negative of the primary (after rectification) and the negative of the secondary (which seems to be connected to the heatsink in your case). Apparently this reduces electromagnetic noise but keeps the secondary at a relatively high voltage with respect to earth ground.BTW, this sometimes causes issues with laptop touchpads working erratically when using two-pronged AC adaptors.More information here:http://www.epanorama.net/newepa/2012/04/02/isolated-laptop-power-supply-issues/

author: wraper
author_rank: Unknown
timestamp: October 26, 2015, 05:04:37 pm
content: This is not a fault and actually how most of the double insulated devices with SMPS behave.

author: isopropilick
author_rank: Contributor
timestamp: October 26, 2015, 09:22:35 pm
content: Absolutely normal, most devices that have no physical land and so have the leak of voltage

author: N TYPE
author_rank: Regular Contributor
timestamp: October 27, 2015, 02:46:10 pm
content: Thats an interesting read samnmax, kinda makes sense being that its a fixed appliance which relies on signal quality.It still astounds me that this can be acceptable though, i mean 100vac is never a good sign (even if it is a high impedance source) you shouldnt feel a tingle when touching a double insulated device! (or any device for that matter).Kinda feel bad now for sending back a perfectly working (and non-faulty) unit for replacement.. Oh well somebody at logitech gets a free sound system
Harmon Kardon PM620 - Page 1
Forum section: electronics / repair

author: rahandford
author_rank: Regular Contributor
timestamp: October 26, 2015, 10:05:24 pm
content: Have a dead unit. Anyone know where I can get the service manual please.Thanks in advance for your help.

author: rahandford
author_rank: Regular Contributor
timestamp: October 27, 2015, 10:43:23 am
content: Thnaks everyone, but I have now managed to locate a copy.

author: crispy_tofu
author_rank: Super Contributor
timestamp: October 27, 2015, 11:30:44 am
content: Can you share it with us?(unless it's in physical form, of course)
HP L2445w 24" TFT repair - Page 1
Forum section: electronics / repair

author: Shirakaba
author_rank: Contributor
timestamp: October 24, 2015, 06:19:07 pm
content: I have been troubleshooting the SMPS in a dead HP L2445w 23" TFT monitor for the past week. Finally found the culprit, a 0.1nF ceramic disc bypass capacitor on VDD of the SG6902 PFC/Flyback PWM Combination Controller. When the capacitor was removed, the switching returned, so I replaced with a similar one from a SMPS in my scrap bin.When I got the power back I could see a whole bunch of dead pixel islands in the bottom of the screen. The person I got it from said it was barely used and worked perfectly until it went black, so my guess is that it is due to transport damage. Is there anything that can be done about this kind of damage, or is all hope lost?

author: SeanB
author_rank: Super Contributor
timestamp: October 24, 2015, 07:51:50 pm
content: Nothing you can do, it will eventually enlarge to a black irregular shape in that area, but if you can live with it it will last years still.

author: Rasz
author_rank: Super Contributor
timestamp: October 26, 2015, 07:57:31 pm
content: person that sold it to you might of lied :/are those blobs static? or do they show up few seconds after powering up?

author: crispy_tofu
author_rank: Super Contributor
timestamp: October 26, 2015, 08:04:09 pm
content: Quote from: Rasz on October 26, 2015, 07:57:31 pmHmmm... I wonder if they had pictures of it working in the listing, unless it wasn't from the Internet

author: Shirakaba
author_rank: Contributor
timestamp: October 26, 2015, 08:17:34 pm
content: It was sold as "not powering on", so there were no pictures of it running. The symptoms pointed in the direction of being an smps issue, which it was (see my first post). I asked the seller specifically if there was anything else wrong with the monitor and he replied it was working perfectly fine until not starting anymore. Of course he could be making it up...QuoteAs far as I can tell they are permanent.
Alternative to Palazzo switch - Page 1
Forum section: electronics / repair

author: edb1984
author_rank: Contributor
timestamp: October 26, 2015, 06:06:23 pm
content: Greetings all.i am looking for a replacement switch for repair job i am attempting on a friends Hobart mixer and i have come to a dead end.the switch on the unit is all chewed up internally and no amount of contact cleaner will remedy the situation so it will have to be swapped out.my knowledge is limited so please bear with me.the switch is branded Palazzo and with some research i have found the company has now stopped trading meaning i cant get a like for like replacement.What i know is;the switch has 4 positions, and has a header cable attached that links to the control board in the mixerresting position is offtwo latching switch positions when turned left (one for low power one for high)then one turn right from the resting off position puts it on high power non latchingso a similar layout to a blender if you catch my drifti have found a link to the data sheet for the switch (see below)http://www.commutatori-palazzo.it/inglese/commutatori/en_13R.htmand here is a photo of the switch itselfmy question, is - what would a similar replacement be with the same switching layout of two on positions and one non latching position?and how will i work out the wiring so i solder the header cable on correct so i don't fry the switch?

author: Vgkid
author_rank: Super Contributor
timestamp: October 26, 2015, 07:32:08 pm
content: Try lookig through the various sealed 4 position rotary switches.
Help for identifying 5.08mm connector - Page 1
Forum section: electronics / repair

author: manu
author_rank: Regular Contributor
timestamp: October 26, 2015, 10:31:21 am
content: Hello,I cannot find a reference for a 2-pin 5.08mm pitch plug with a cross style section (please see attachments).This connector is a part of a swing-gate opener and supplies 24Vdc.If you know where to find it and it pcb corresponding header, please let me know.Thanks,

author: SL4P
author_rank: Super Contributor
timestamp: October 26, 2015, 01:21:23 pm
content: Altronics has them in 5.0mmThis may give you a lead to find the 5.08mm version...http://www.altronics.com.au/p/p2370-stelvio-36-way-5mm-pluggable-terminal-plug/http://www.altronics.com.au/p/p2372-stelvio-36-way-5mm-pcb-mnt-pluggable-terminal-socket/

author: manu
author_rank: Regular Contributor
timestamp: October 26, 2015, 02:11:29 pm
content: Thank you !You are probably right, it might be a 5mm pitch as I don't find any 5.08mm header with this footprint.
AC-AC transformer fried? - Page 1
Forum section: electronics / repair

author: stev.dk
author_rank: Regular Contributor
timestamp: October 25, 2015, 08:44:43 pm
content: I have an AC-AC transformer rated at 230VAC primary and 2x27VAC secondary. The secondary coils measure 0,71 ohms and 0,77 ohms, so they are not opencircuit. When measuring the AC output with no load, i get only 51-52mVAC. Is this because the transformer is dead, or could it simply be because i have no load hooked up to it?

author: Gyro
author_rank: Super Contributor
timestamp: October 25, 2015, 08:50:57 pm
content: You haven't posted the primary resistance - I suspect that the primary is open-circuit. There may also be a thermal fuse in series with the primary that has opened.Edit: running it without load won't have damaged it or caused false readings.
PCB rework - Page 1
Forum section: electronics / repair

author: R_G_B_
author_rank: Frequent Contributor
timestamp: October 25, 2015, 10:29:00 am
content: I was doing some PCB rework on a graphing multi meter.I used a hot air station 240 degree C. Had a little success. I decided to up the temperature to 320 degree as it was taking a little too long to heat the solder on the board. Now the board does not switch on I am concerned i may have damaged components.I did try to avoid heating the components. I checked there is 5V reference going to the components.I see re flow ovens operate at 250. So it looks like i went to high in temperatureR_G_B_

author: Jeroen3
author_rank: Super Contributor
timestamp: October 25, 2015, 12:19:10 pm
content: With hot air you can increase the temperature if you need a larger area to be heated. As you'd need to desolder a SMD mosfet with heat plane.Since you can change the airflow the actual temperature on the board surface may be less than that the nozzle sensor measures.You can get hot air stations with an extra temperature sensor to compensate this.What type of components where in the heated area?

author: R_G_B_
author_rank: Frequent Contributor
timestamp: October 25, 2015, 03:40:48 pm
content: Quote from: Jeroen3 on October 25, 2015, 12:19:10 pmResistors, capacitors, transistor ROM ram CPU MOV diodes etc....R_G_B_
Leader LBO-520 Dual Trace Oscilloscope issues - Page 1
Forum section: electronics / repair

author: YoshiKnuuckles
author_rank: Contributor
timestamp: October 24, 2015, 09:35:05 pm
content: I recently obtained this old scope and I'm having issues with it. Instead of trying to explain it, I decided to take a video of it's ailment.https://youtu.be/GypDtO2W9rEI should probably give some background about myself, and the scope. I'm currently a first-year EET student who is attempting to set up a lab at home to supplement my college studies. This scope was something I picked up in a lot with some other old electronics, and it was basically free. I'm trying to troubleshoot what's wrong with it, but I have no clue where to start with this thing! Would be awesome to get it working properly again, I was hoping to use it as a learning starter scope.Any help or guidance with this is appreciated. I should be capable of doing the rework on the unit myself. However, I need help determining what needs replaced, or if the unit is beyond economical repair (I doubt this is the case.)

author: tautech
author_rank: Super Contributor
timestamp: October 24, 2015, 09:43:17 pm
content: Welcome to the forum.I've not watched your vid yet but a helpful pdf on CRO troubleshooting can be found in the Repair Links thread at the top of this board.

author: oldway
author_rank: Super Contributor
timestamp: October 25, 2015, 07:26:28 am
content: What about channel B ?Does it work well or does it have the same problem as channal A ?

author: YoshiKnuuckles
author_rank: Contributor
timestamp: October 25, 2015, 10:30:54 am
content: Channel B shows almost all the same symptoms as Channel A. Both channels seem to function as they should, the only real issue with the scope is what I've shown.I looked over the CRO troubleshooting guide, and I'm having a bit of trouble figuring out where to start. A lot of helpful information in there though.
Help needed for Ramsey Electronics AR1C Airband Receiver - Page 1
Forum section: electronics / repair

author: gaurav279
author_rank: Contributor
timestamp: October 24, 2015, 10:48:20 am
content: Hi Folks,I have made a Ramsey Electronics Aircraft Band Receiver AR1C but its not catching any Airband Signals.Instead I hear some FM Radio Channels on it.Any one to help me on this

author: PA0PBZ
author_rank: Super Contributor
timestamp: October 24, 2015, 10:49:58 am
content: Yes, but please don't post multiple times, I already replied in the other thread.

author: gaurav279
author_rank: Contributor
timestamp: October 24, 2015, 08:23:35 pm
content: Thanks for the post but can you please give me the link for this Thread...

author: PA0PBZ
author_rank: Super Contributor
timestamp: October 24, 2015, 08:28:00 pm
content: Quote from: gaurav279 on October 24, 2015, 08:23:35 pmhttps://www.eevblog.com/forum/beginners/troubleshooting-help/