hybridfree/eevblog-posts huggingface dataset:
Marconi 2438 Timer/Counter service manual - Page 1
Forum section: electronics / repair

author: Torrentula
author_rank: Regular Contributor
timestamp: February 28, 2016, 02:45:39 pm
content: Hello!I recently got a Marconi 2438 universal timer/counter from eBay and I'm looking for the service manual for this unit and figured this would be the best place to ask.The best I could come up with until now is the user manual, which doesn't really go into the digital interface option details.I'm trying to tap into the digital interface pins throughout the device with an MCU in order to hook it up to a PC.Does anyone here have some documentation on this unit, other than the user manual fromhere?Thank you,Elia

author: Andy Watson
author_rank: Super Contributor
timestamp: February 28, 2016, 02:59:02 pm
content: Quote from: Torrentula on February 28, 2016, 02:45:39 pmHave you tried the service manual for the 2437 ? It appears to be the same but with limited frequency response.

author: Torrentula
author_rank: Regular Contributor
timestamp: February 28, 2016, 05:08:49 pm
content: Quote from: Andy Watson on February 28, 2016, 02:59:02 pmThanks for pointing me toward that manual, it seems like they are indeed the same unit save for the frequency range.I've had another look at the manual and it indeed also includes a pin description of the data interface.
Chinese DA converter - Page 1
Forum section: electronics / repair

author: Roeland_R
author_rank: Regular Contributor
timestamp: February 28, 2016, 08:34:27 pm
content: Hi folks,I bought a cheap DA converter to connect my tv with toslink output to a 25 year old marantz receiver. It's a cheap chinese converter but it should do it's work. After connecting sound seems to be ok, but when watching a movie with much dynamic it sounds sometimes disturbed. I tried also another Technics receiver, same result. Perhaps I can change the output level of this converter, so I am looking for a schematic of it. Does anybody have the schematic already? As you can see on the pictures solderings are not very good. I am wondering if the 344C 1325 is the amplifier. Google doesn't help me here. I did find a pdf of the cirrus.

author: wraper
author_rank: Unknown
timestamp: February 28, 2016, 09:45:48 pm
content: Q1 and Q2 connected directly to the RCA connectors seem like a strange schematic decision. IMO the distortion lies somewhere there. EDIT: probably they are for muting.

author: wraper
author_rank: Unknown
timestamp: February 28, 2016, 09:56:01 pm
content: By the looks of it, there is no proper output filter for CS4344 DAC.https://www.cirrus.com/en/pubs/proDatasheet/CS4344-45-48_F2.pdf

author: Roeland_R
author_rank: Regular Contributor
timestamp: February 29, 2016, 06:32:26 pm
content: Quote from: wraper on February 28, 2016, 09:56:01 pmThanks for your help. I will try to draw the schematic in kicad. Also thinking of ordering an ad converter to connect to my function generator to check the signals of the da converter. TV doesn't fit on my workbench
Faulty Philips LCD TV - Page 1
Forum section: electronics / repair

author: R1Geoff
author_rank: Newbie
timestamp: February 24, 2016, 02:02:57 pm
content: Hi all I am new on here after watching some of the youtube video's spiked my interest, anyway I have a Philips LC320W01AGK1 Tv now it comes on goes off as it should never had an issue with it except for an on pcb fuse that I changed a few years ago it has now developed another fault as in it has a really bad green tint to the picture the menus seem good just the tv picture is green.Any help would be appreciated Geoff

author: SAUL BRITTO
author_rank: Frequent Contributor
timestamp: February 25, 2016, 01:32:46 pm
content: Look the flat cable,Tcom or master signal board. There's a guy here in my country that solved problems like the your with, insulating some contacts of flat cable,look for Waldyr Maior on youtube.

author: SAUL BRITTO
author_rank: Frequent Contributor
timestamp: February 25, 2016, 01:35:37 pm
content: If you has an oscilloscope look the digital RGB. One of that signals RSDS or LVDS can be in lack.

author: R1Geoff
author_rank: Newbie
timestamp: February 28, 2016, 11:31:21 am
content: Hi thanks for your help with this ~I will look in to what you have told me and will be sure to let you know how things work out.Best Regards Geoff
Sony CCD-V30E - Page 1
Forum section: electronics / repair

author: Djolecam
author_rank: Newbie
timestamp: February 28, 2016, 11:33:24 am
content: Hi, i recently bought this old camcorder, i took my camera to Sony repair centar and they tell me is too expensive to repair no one manufacturing spare parts for this camcorder.My problem is when i turn on camera i see in viewfinder white picture. Then i remembered to connect video/audio ports from camera to tv. On tv screen i see blue picture and i hear my voice from microphone.Do you have any solution from me? What to repair?

author: Fraser
author_rank: Super Contributor
timestamp: February 28, 2016, 02:14:50 pm
content: Very sorry to report that I have binned at least 10 similar era camcorders recently. They have no value anymore so people do not tend to repair them. Your fault will likely be in the power supply circuits but I doubt you will find someone willing to spend time diagnosing such a fault. I can understand why you might want to do so as a learning experience, but these units really are not worth the effort for most people. Such cameras sell for around £5 in UK charity shops. The service manual is needed for a repair and, if not available for free on the internet, will cost around £25...... 5 times the value of the camera.Sorry I do not have better news. I only buy such cameras to harvest the optical block and viewfinder. The rest is good only for scrap or SMT desoldering practice.Fraser

author: Djolecam
author_rank: Newbie
timestamp: February 28, 2016, 03:46:13 pm
content: Thank you for your quick reply, i will try to buy another camera.

author: Fraser
author_rank: Super Contributor
timestamp: February 28, 2016, 04:51:54 pm
content: Please be aware that buying any camera from the 1990's or early 2000's carries the risk of the tap transport being faulty due to degraded rubber parts. If you can possibly afford it, buy a camcorder with a hard disk, CD-R or flash memory storage medium. These will, be more modern and will not suffer the tape transport issues common to older units.Camcorders have become pretty much obsolete for some people as they use their mobile phones instead. I still have modern camcorders but use them very rarely. I am no videographer ! Mine all use hard disk storage. Panasonic appears a reliable brand for such units but I would avoid JVC.Fraser
P2370 LCD generate buzzing if the brightness is less than 100% - Page 1
Forum section: electronics / repair

author: muhamadamru
author_rank: Contributor
timestamp: February 20, 2016, 07:18:14 pm
content: Hello :i have the following screen :http://www.newegg.com/Product/Product.aspx?Item=N82E16824001330and i noticed that if i decrease the brightness less than 100% a buzzing sound heard from the screen , like zzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz heard if i put my ear on the pack of the display.i remember that i had this problem and i get the screen repaired by somebody, now i want to know the cause of the problem and to fix it if possible and i am writing here hoping somebody help me.Thanks in advance.

author: muhamadamru
author_rank: Contributor
timestamp: February 21, 2016, 10:01:14 am
content: up

author: EPTech
author_rank: Regular Contributor
timestamp: February 21, 2016, 04:10:59 pm
content: Hi There,It is probably an EL backlit panel which is in essence a ga discharge tube. That one needs a high voltage converter. The buzzing you here is audible noise coming from the transformer. Usually it is more prominent on lower duty cycles, when you decrease the BL brightness. The converter is usually a separate (narrow) PCB. They are massively available. Sometimes there a multiple converters in a panel, they may also be combined on one PCB.

author: muhamadamru
author_rank: Contributor
timestamp: February 22, 2016, 07:23:52 pm
content: any solution ?like changing the capacitors ?

author: muhamadamru
author_rank: Contributor
timestamp: February 28, 2016, 06:44:50 pm
content: thank you very much but i didn't understand a lot from what u said
Agilent N9340B 3GHz spectrum analyser repair help - Page 1
Forum section: electronics / repair

author: jeremy
author_rank: Super Contributor
timestamp: February 23, 2016, 01:52:43 pm
content: Hi all,I got hold of a heavily optioned but also very broken Agilent spectrum analyser for a decent price. First thing I noticed was that someone has had a go at fixing it as well; I can hardly blame them. Anyway, to cut a long story short, the FFC between the main board and the keyboard had some shorts across it, and this blew out the main CPU, video also seems to be dead now. CPU unfortunately is an obsolete part which is also a 324 LFBGA, but I found some and replaced it. I only discovered the keypad problem after I killed the new CPU by plugging the keypad in, so I ended up having to solder two separate chips; that was a stressful day! Also burned myself finding out which chip was shorted (200C apparently)So right now, the spectrum analyser works over USB and Ethernet; which I am pretty happy with; I don't need it to be portable. However, it has just become clear to me that there is a problem with the RF frontend; the input signal disappears once I go above ~2.1GHz. At 2.2GHz it is completely gone. The noise floor is the same across the whole span however.I can't find a service manual for this (even called the keysight service center, they said that it doesn't exist), nor even a block diagram of what mixer configuration or IFs it uses. I wouldn't say that this sort of RF is my specialty, so I'm putting it to everyone; do you have any hypotheses of what could cause this behaviour?My first thought is that it is doing the downconversion through multiple paths, and one of them is dead. But given that this is a compact modern analyser, 3GHz BW seems like it could be done in a single path and I'm sure they would try to do so.I'm very busy with other stuff at the moment, but I'm going to open it up again and take some pictures in the future. First though, I need to get hold of another spectrum analyser to fix this one...

author: 1design
author_rank: Regular Contributor
timestamp: February 25, 2016, 08:48:14 pm
content: Looking forward to see the pictures of the inside, I own the same unit but never dared to open it as it still has the warranty seals on it.I will try to help you reverse engineer the microwave path in you are interested.BR

author: KJDS
author_rank: Super Contributor
timestamp: February 25, 2016, 09:35:14 pm
content: Does it provide a 1st LO output?
Fluke 33X series clamp meter segments swapped - Page 1
Forum section: electronics / repair

author: Shock
author_rank: Super Contributor
timestamp: February 25, 2016, 06:39:48 am
content: Looking at a Fluke 33X series clamp meter with a display issue, seems some of the segments are swapped or transposed in some way. Occurs on all measurements and otherwise the clamp meter seems operational.When on AC and DC and Amps the display shows A.A instead of 0.0- segments D and G are swapped on both digits.When on Ohms the display shows 0 n instead of 0 L- segments D and G are swapped and possibly F and C.I cleaned and swapped the two conductive rubber pads around and upside down several times which I'm fairly sure should have showed different symptoms if a cause. I also cleaned the PCB contacts and display contacts.I lifted the backlight and cleaned the circuit and IC underneath, around the IC area I got a strange blue dye/ink so I cleaned that until removed. I did this without removing the backlight so couldn't get a good look at where it came from. It may have been a date stamp on the back of the backlight or something as there was a smudge there as well that I cleaned off.Any ideas?

author: rf+tech
author_rank: Frequent Contributor
timestamp: February 25, 2016, 02:37:41 pm
content: Shock,Very odd problem. My first thought, because the photo is tiny, that the LCD may be installed upside down. So off to Google Images in search for a larger image.Selecting the largest image available landed me on Fluke 33xRecallpage:http://en-us.fluke.com/customer-service/safety-notices/33x-recall.htmlA bit off on a tangent, perhaps your meter is covered and the display problem is related as described:QuoteRF+ Tech

author: Shock
author_rank: Super Contributor
timestamp: February 25, 2016, 03:45:51 pm
content: Its not in the recall. The other display symbols seem fine it's only ever a few segments swapped around on each digit. I didn't take a photo of it but it's as described.
ceramic caps upping voltage ? - Page 1
Forum section: electronics / repair

author: KD0CAC John
author_rank: Frequent Contributor
timestamp: February 24, 2016, 04:05:54 pm
content: I am chasing issue with Kenwood TS-820 with digital display issues and adding solder to top side of PCB to rectify problems and during this , I may have damaged a ceramic cap 33p .I had a 33p same size but my box said 100 volts , and many times before some up grading when replacing cap of most types , going from lets 16v to 32v has been ok , but now if the old one was lets say a 12v cap & put in the 100v cap , could making that big a jump in voltage be an issue ?Thanks

author: MrSlack
author_rank: Frequent Contributor
timestamp: February 24, 2016, 04:07:04 pm
content: It will be fine. That's the maximum voltage the dielectric can handle safely before it breaks down rather than any specific measure of capacity.Edit to add some rationale: most voltage reductions at that sort of scale is about keeping costs low and devices smaller as you need larger capacitors with more dielectric to handle higher voltages which costs more money.Edit 2: there are some differences with stray inductance and series resistance as well but between 12-100v there is probably little difference.

author: KD0CAC John
author_rank: Frequent Contributor
timestamp: February 24, 2016, 05:23:16 pm
content: OK thanks .
Schaffner NSG2050 - Low output drive capability - Page 1
Forum section: electronics / repair

author: AndersJ
author_rank: Frequent Contributor
timestamp: February 26, 2016, 01:03:41 pm
content: The output voltage is half of what is expected, when the output is open circuit.With a small load the output voltage falls dramatically.The waveform looks good, timing wise.The instrument has a 10 uF 10KV floating capacitor that is connected to theoutput at the time of the surge. Connection is made with contactorsthat can both positive and negative output polarity.Both output polarities, and both output connectors have the same problem.My hypothesis is that the negative side of the capacitor is not being groundedwhen the pulse is generated, thus causing weakly driven outputs.The only place I have seen, where this grounding might take place,is on the impossible to reach circuit board at the rear end of the instrument.Does anyone have a service manual?All suggestions are more than welcome.Anders J
Help - how to remove cooling fan - Page 1
Forum section: electronics / repair

author: xrunner
author_rank: Super Contributor
timestamp: February 24, 2016, 02:37:33 pm
content: How the hell do I remove this fan? It's attached with some sort of system that's seemingly "permanent". I've tried for an hour to see how it can "unlock" but I have not found any way to pull the pins out from the other side - I suppose so that you can't replace the fan yourself. Has anyone seen this before? How do I get the attachment thingies to unlock?Signed, frustrated

author: orion242
author_rank: Unknown
timestamp: February 24, 2016, 02:51:06 pm
content: Pull the center pin put and it should pop right out.

author: xrunner
author_rank: Super Contributor
timestamp: February 24, 2016, 02:54:30 pm
content: Quote from: orion242 on February 24, 2016, 02:51:06 pmNo it doesn't. I've already said I've tried everything I can. It will not come out. That is all hard plastic. I can't even see how they put it together.

author: alsetalokin4017
author_rank: Super Contributor
timestamp: February 24, 2016, 02:56:06 pm
content: Looks like a plastic pop rivet. If you look on Ebay you can find many of these, some look like exact replacements for what you're showing. They are not designed to be removable. Just cut the protruding part off with your shear-cutters. You can replace them with small screws, washers and nuts, with a little locking compound like nail-polish or superglue on the nut so it doesn't vibrate loose.

author: xrunner
author_rank: Super Contributor
timestamp: February 24, 2016, 03:19:37 pm
content: Quote from: alsetalokin4017 on February 24, 2016, 02:56:06 pmAh OK, well that explains it. I just hadn't run across them before - thanks.
LEMO FFA.3Y.415 connector has loose cable - Does anyone know how to open it - Page 1
Forum section: electronics / repair

author: AndersJ
author_rank: Frequent Contributor
timestamp: February 23, 2016, 01:26:24 pm
content: It is a high voltage Teseq cable that has come loose.I do not want to make it worse by trying to open the connector in the wrong way.Does anyone know how to open it.

author: Andy Watson
author_rank: Super Contributor
timestamp: February 23, 2016, 01:36:26 pm
content: I have used similar Lemo plugs - they separate by undoing the collar where the cable enters. The collar should unscrew with respect to the main body. The internal cable-clamp, insulation and pin(s) should then slide out of the body.

author: AndersJ
author_rank: Frequent Contributor
timestamp: February 23, 2016, 02:05:02 pm
content: Thanks Andy, that was easy.The connector came apart easily.The inner conductor to the tip was indeed loose.Now I need to figure out how to get the tip out.I assume it must be pushed back, but I'm afraid to use to much force .I cannot see a locking mechanism.Perhaps it is similar to a BNC connector, where the inner conductor keeps it in place.

author: azer
author_rank: Regular Contributor
timestamp: February 24, 2016, 01:15:13 pm
content: The tip should slide out according to the instructionswww.lemo.com/catalog/ROW/UK_English/high_voltage.pdfpage 14.

author: AndersJ
author_rank: Frequent Contributor
timestamp: February 24, 2016, 02:05:51 pm
content: Thanks azer.I have been in contact with Lemo about this.Normally its exactly as you describe it.In this case however,the tip is not pushed in as expected, but firmly fastened in the housing, and soldered.On top of the tip is a non conducting protective cover, and you guessed it, it does not come off.I have ordered new connectors.I will also add shrink tubing to the cable to increase its diameter,hoping for better friction next time, between the cable and the cable clamp.
Little Keithley 2304A repair project - Page 1
Forum section: electronics / repair

author: TiN
author_rank: Super Contributor
timestamp: February 24, 2016, 11:16:55 am
content: Well, I think it's bit over the top using K2400 SMU for powering fans and charging batteries, so time to buy lab PSU.And no, going to shop and ordering some fancy Keysigh is not an option for real jedi.Random low bid was put on random item on ebay (dangerous!), and I happened to win the thing.Seller description:For parts or not workingSorry for bad photo, it's from item description.Will see what's wrong with it when it arrives. Shipping is almost same cost as unit itself.Based on photos in another EEVBlog thread about 2304A there is Keithley 2000 ADC in it, and copy of digital controller from 2000 as well.After unit repair, some pimping up and full recalibration will be performed. I'm not decided yet which display should I use, VFD 16 x 2 or OLED 16 x 2 ?

author: KJDS
author_rank: Super Contributor
timestamp: February 24, 2016, 01:33:12 pm
content: I've fixed a couple of that family just by unplugging and reconnecting all the internal connections.Whilst I hope yours is that easy to repair, it will make for a dull thread.
Big Resistor Burn On PCP Help - Page 1
Forum section: electronics / repair

author: XMA
author_rank: Contributor
timestamp: February 25, 2016, 09:26:06 pm
content: Well I have a old IBM power supply I need to fix and well first it did not work so I had checked for bad caps and so I did found 2 bad ones and has replaced them and still the power supply does not work now I check other places on the 2 board massive power supply and on the 2 board connector board there is a burn mark from a resistor and another component, the resistor was so hot that it burned of 2 of its color codes and I don't know if it's normal but another component is realy dark but not black and when I look the part up on the internet it looks totally different, like internet blue and mine dark and I was need in help with, if the PCB is that burnt is the resistor dead and the other component and is there a way to test a resistor out without a multi meter and I am new and it's my first post

author: lowimpedance
author_rank: Super Contributor
timestamp: February 26, 2016, 12:02:18 am
content: You will need to at least test the reisistor with an ohm meter (dmm or whatever has an ohms function!) to try and see if it has a sensible value or is open circuit. Being a power resistor I would say its value will be on the lower side. Do you know someone who has a dmm ?, who can check for you. (Im guessing you don't have one!). Also should test the diode is not shorted as well.It could be the resistor just runs on the hot side and after all these years of running this 'old supply' it has slowly cooked itself and its surrounds.The ceramic disk capacitor is most likely okay (cannot read its value but the volt rating is 1kV). Diode looks to be a standard 1n4007.Maybe you should think of getting a DMM if you intend to tinker with electronic things, get a reasonable one and you will not regret it. (note there are PLENTY of threads on here asking about "which multimeter shouls I get".
Finding a replacement cap: peh534mbi4150a3 - Page 1
Forum section: electronics / repair

author: TumeSai
author_rank: Newbie
timestamp: February 21, 2016, 06:17:35 pm
content: Hi!I have an APC UPS, which has a blown up cap I need to replace. But it seems that the one I need is very hard to come by. I am not an electrical engineer, so I have no idea what would be a suitable replacement.Could anyone help me to find a replacement? The specs for the original one are here:http://80.93.56.75/pdf/0/2/0/5/7/02057509.pdfThank you++T

author: MSO
author_rank: Contributor
timestamp: February 22, 2016, 03:19:51 am
content: As best as I can tell, it is a KEMET Aluminum electrolytic from the PEH534 series.1500uf 63VDC with an unknown case size and unknown (but suspected to be snap in) terminals. You'll have to determine case size and termination mode from the existing capacitor.The Kemet datasheet:http://www.kemet.com/Lists/ProductCatalog/Attachments/398/KEM_A4024_PEH534.pdfAnd a rather cryptic notice that Kemet transferred the manufacture of the PEH534MBI4150A3 from Suzhou (China) toEvora (Portugal) and have assigned the a new KEMET part number of A561CK152U063F:www.ttiinc.com/object/io_1435242362847I won't attempt to load the link in your original post, so I may be repeating what you already know.Thanks to blueskull for the correction.

author: TumeSai
author_rank: Newbie
timestamp: February 23, 2016, 02:08:58 pm
content: Thank you both. I'll check these.
Help repair Agilent oscilloscope DSO6032A - Page 1
Forum section: electronics / repair

author: iwqlt
author_rank: Newbie
timestamp: February 23, 2016, 06:18:40 pm
content: Hello to all,I have a DSO6032a Agilent oscilloscope purchased from a colleague of mine two years ago, used with caution until a few days ago, he has now suddenly following problem:when he powers, the LCD display lights up for a brief moment then he goes black, and the front LED panel cycle from bottom to top in an endless loop.I sent the DSO6032A Keysight in Milan for a repair estimate and had the following diagnosis: the replacement of the "System PC board assembly" for the price of 4822Euro + VAT.For me the price for this repair appears unsustainable.I need help or advice to diagnose and repair the electronic board if possible, or reporting some links on the topic.I thank you for your advice possible.Gino.

author: SAUL BRITTO
author_rank: Frequent Contributor
timestamp: February 24, 2016, 01:03:45 am
content: First of all: P.S! Power supply.

author: iwqlt
author_rank: Newbie
timestamp: February 24, 2016, 03:39:41 pm
content: Hellobefore sending my oscilloscope at Keysight I tested the power supply following the service manual instructions, and appeared functional. At keysight laboratory diagnosed that the PC board system has to be replaced and that they do not repair more component level.Still waiting on who can give me advice.Thank youGino

author: Jwalling
author_rank: Unknown
timestamp: February 24, 2016, 03:59:50 pm
content: Quote from: iwqlt on February 24, 2016, 03:39:41 pmWhat's the serial # of the unit? There is a service note for this series and that type of failure.http://literature.cdn.keysight.com/litweb/pdf/DSO6104A-02.pdfI know that the pdf mentions the 1GHz version, but using your model # and selecting service notes still directs you here:http://servicenotes.literature.keysight.com/litapp/SearchSN.do?method=openExternalSNSearch&prodNum=DSO6032AThere a place on Keysight's web pile where you can enter the serial # to see if the system board was already replaced.Jay

author: Carrington
author_rank: Super Contributor
timestamp: February 24, 2016, 04:16:21 pm
content: It may not have a solution, but:Have you tried to boot from USB?http://www.keysight.com/main/editorial.jspx?ckey=670496&id=670496&lc=eng&cc=GBAdditional Information:http://cp.literature.agilent.com/litweb/pdf/54695-92006.pdf
Philips PM 5715 pulse generator - Schematic diagram anyone? - Page 1
Forum section: electronics / repair

author: AndersJ
author_rank: Frequent Contributor
timestamp: March 04, 2016, 05:41:24 pm
content: Today I managed to somehow blow the output stage,or possibly the negative supply, of my pulse generator.It no longer outputs negative pulses and has problems pulling down, towards ground.Does anyone have the service manual or schematic diagram of the PM 5715?

author: tautech
author_rank: Super Contributor
timestamp: March 04, 2016, 07:38:42 pm
content: Try this one but wait for the "Get Manual" to appear in the middle of the page, then click it.http://elektrotanya.com/philips_pm5715_sm.pdf/download.html

author: AndersJ
author_rank: Frequent Contributor
timestamp: March 04, 2016, 08:11:26 pm
content: Thank you, very much!Anders
Eizo S2243W with stripes. Repair possible? - Page 1
Forum section: electronics / repair

author: Campus
author_rank: Contributor
timestamp: February 20, 2016, 01:51:24 pm
content: Hi,I have an Eizo S2243W which shows ugly stripes when when being powered up. I made some photos of the found boards inside. I couldn't see anything obvious that needs fixing. Does it make sense to repair these types of errors and what should I start to check?Best regards,Campus

author: SAUL BRITTO
author_rank: Frequent Contributor
timestamp: February 21, 2016, 09:11:26 pm
content: If it's a tv...

author: SAUL BRITTO
author_rank: Frequent Contributor
timestamp: February 21, 2016, 09:13:48 pm
content: Is in portuguese but you will understand.
[FIXED] Mastech DC Power Supply HY3005DX (Rebranded PS305D) - Blown by 220VAC - Page 1
Forum section: electronics / repair

author: Zucca
author_rank: Unknown
timestamp: February 21, 2016, 05:11:21 pm
content: 2 Bad decisions:1) Buying a crap PS like this:https://www.eevblog.com/forum/testgear/mastech-dc-power-supply-hy3005dx-cheap-and-very-impressing!/2) Thinking the outputs are isolated from the mains. I forgot there was a little metal tab between the - pole and the earth ones in the middle.Short Story: I completely forgot the minus pole was connected to earth (by a metal tab), and I ended up in my setup to connect the 220VAC main to the minus... BOOOM!The crappy PS did not survive: after turning it on it was going at 40V output and then decrasing to 0V, no response from the adjunting knobs.I opened the unit expecting to find a black burned spot somewhere, no no it looked just fine crap as always, so next step I got the schematics from here:https://www.eevblog.com/forum/repair/new-power-supply-ps305d-not-regulating-and-running-over-voltage-and-current/Few measures laters I understood the protection circuit balcony (not reported in the schematics)was kicking in by cutting the power after the diode bridge BD1. That's why I was getting 40V and then 0...By excluding the protection the output was solid at about 47V with no response to the adjusting knobs. After a few second I was powering down the unit because I didn't want to damaging it further somehow.So I started to check components left and right (the the brain turned on...) and I found the bad guy: D116 1N5399 was shorted. Replaced with a bigger one ECG5804 (didn`t have the exact replacement) and ready to go.Here what I learned:1) If the R106 is burning hot and there is decoloration on it, it`s a design feature not a failure (in all the pictures I saw has that resistor color looks cooked).2) They don't even bother installing proper connectort between the different bards (ie protection balcony and main board), just use some hot glue to hold those thin cables down.3) The big 5W power resistors R104 and R103 marked 5WR18J are supposed to be 180mOhm and they are not shorted. I didn`t know "R"="."4) Check all the solder joints, some of them are scary.This power supply in general has a quality level comparable to a "steaming pile of HS" (quoting Louis Rossman).Since it could be a popular unit to beginners, I wanted to share hoping to help somebody out there.

author: station240
author_rank: Unknown
timestamp: February 21, 2016, 07:38:48 pm
content: Actually I'd expect you'd have a lot more to fix if they hadn't tied negative output to earth.This sort of product build quality was standard, back in 1993. Really no excuse these days for shoddy wiring, glue as a cable restraint, and useless solder joints.
Dell Latitude LED Backlight Driver - Page 1
Forum section: electronics / repair

author: Ziginox
author_rank: Contributor
timestamp: February 12, 2016, 05:12:59 am
content: Long story short, the screen cable got pinched and shorted, causing this part to pop. The LED backlight no longer works. I've replaced the motherboard but can't see the point of leaving the original board alone when it seems to be just one part causing the failure, however I'm having some trouble identifying the parts. I've attached photos of the blown part and the same part on the new board. Silkscreen says Q21, the remnants of the old part say D5, and the new one is marked "654" followed by a tall plus sign. I think it'sthis Fairchild partbut want to be sure.

author: ThomasDK
author_rank: Regular Contributor
timestamp: February 12, 2016, 05:28:18 am
content: You can usually find schematics for Lattitudes - might be worth a shot?Thomas

author: Ziginox
author_rank: Contributor
timestamp: February 13, 2016, 03:31:38 am
content: Quote from: ThomasDK on February 12, 2016, 05:28:18 amThank you for the suggestion. I looked around and couldn't find any that weren't suspiciously hidden behind a paywall.

author: Rasz
author_rank: Super Contributor
timestamp: February 13, 2016, 03:36:23 am
content: we might help you ... if you would mention model number

author: Ziginox
author_rank: Contributor
timestamp: February 13, 2016, 05:32:38 am
content: Whoops, I completely spaced it. It's a Dell Latitude E6430, the C/N of the board is 2V2HC.

author: Monkeh
author_rank: Super Contributor
timestamp: February 13, 2016, 02:25:52 pm
content: You didn't look too hard, the first result on Google was a freely downloadable schematic - and the fourth page confirms your guess, it's an FDC654P.

author: Ziginox
author_rank: Contributor
timestamp: February 13, 2016, 02:32:21 pm
content: Could you share what search term you used? I'm still unable to find it. Thank you for confirming my suspicions about the chip.

author: Monkeh
author_rank: Super Contributor
timestamp: February 13, 2016, 02:34:04 pm
content: 'dell latitude e6430 schematic', as Google suggested - common search terms often give relevant results.

author: Ziginox
author_rank: Contributor
timestamp: February 13, 2016, 02:43:39 pm
content: Odd, for me the 5th result was finally it, initially I didn't visit it because it was in a language I don't even recognize.Either way, thank you for your help!

author: Ziginox
author_rank: Contributor
timestamp: February 20, 2016, 07:24:44 pm
content: Thanks guys, I ordered the part and successfully replaced it!
OEM car radio wont power up... - Page 1
Forum section: electronics / repair

author: kasumyku
author_rank: Regular Contributor
timestamp: February 20, 2016, 12:56:44 am
content: Hi guys,Not sure where to post this ( beginners or repair section), I guess its a bit of both...I'm a newbie and still learning about electronics so please have a bit of patienceI came into possession of an Vw OEM radio, label says Premium 8.Person who I got it from said that it stopped working suddenly and it wont turn on. I googled a bit about it, not much I could find except that its a common issue with these units.So far I have tried powering up, checked fuse, opened it up but.... man I'm really lost here....I really don't know where to start with troubleshooting this fellow.Any tips on where to start would be much appreciated!!!

author: Rerouter
author_rank: Super Contributor
timestamp: February 20, 2016, 01:10:24 am
content: for VW, your going to need to to emulate the canbus ignition message, most recent models only have a permanent supply and are woken up by the data bus,

author: kasumyku
author_rank: Regular Contributor
timestamp: February 20, 2016, 01:54:09 am
content: I didn't wanted to get more into details but that's another part of me trying troubleshooting this unit...My brother let remove his WORKING radio from his VW Tiguan and replace it with this malfunctioned radio( to see if its gonna turn on) and no luck on getting this one powering up..... so it must be something else.BTW the only thing I got from this step of troubleshooting is that now I have to get a radio code for his head unit, which is about $100 bucks from VW stealership ...Anyways, I guess that's the hard way of learning more about electronics.Once again, any tips on steps of troubleshooting this unit would be much appreciated !!!!

author: Rerouter
author_rank: Super Contributor
timestamp: February 20, 2016, 02:49:07 am
content: Looking at what i can find, the radio code is in the 95128 eeprom inside it, but it seems its only been discovered how to decode the first 2 digits,Care to post all the details on the problem radios sticker, i may be able to find a wiring diagram or similar
CCTV Camera Repair Fortec DWS-6060H - Identifying component - Page 1
Forum section: electronics / repair

author: kammysz
author_rank: Newbie
timestamp: February 20, 2016, 11:39:37 am
content: Hello,I have a CCTV Camera Fortec DWS-6060h. It contains two cameras - one is for black and white picture and the other one only for colour picture. The colour one doesn't send a signal. It turns out that two elements were burned out. One is tantalum capacitor on signal line and the second is strange component by Microchip. It is marked only with digits: 934 1031. I measured it and it is shorted between legs: 1,2 and 4. Does anyone of you know what kind of element is it? I am attaching photos of PCB and this burned out element.

author: bktemp
author_rank: Super Contributor
timestamp: February 20, 2016, 12:06:58 pm
content: Quote from: kammysz on February 20, 2016, 11:39:37 amIt is not Microchip but Mitsumi: MM1031, Video Amplifier

author: kammysz
author_rank: Newbie
timestamp: February 20, 2016, 12:29:34 pm
content: Thank youLogo on chip leads to Microchip. This Mitsumi chip has VCC=5V and supply voltage in circuit is 12V. Now I have to only find something similar on higher Supply Voltage.EDIT: I checked again supply voltage and it is 5V Line not 12V, I made mistake at previous measurements.
HP8657A Signalgenerator - Output distorted at > 15 dBm - Page 1
Forum section: electronics / repair

author: AndersJ
author_rank: Frequent Contributor
timestamp: February 17, 2016, 09:14:56 am
content: At higher output levels,approximately 15 dBm and higher the output sine wave is distorted.The distorsion happens for all frequencies.The output is terminated with 50 Ohms.I would like to believe this is NOT normal but have nothing to compare with.Can anyone do a comparison and let me know.If my generator has a problem,all repair suggestions are more than welcome.Thanks,Anders J

author: Kilrah
author_rank: Unknown
timestamp: February 17, 2016, 09:56:33 am
content: From what I can find with a quick search:QuoteSo you shouldn't be exceeding +10dBm at that frequency, and you likely found out why.

author: KJDS
author_rank: Super Contributor
timestamp: February 17, 2016, 11:29:22 am
content: In the words of so many car salesmen,"they all do that sir"

author: AndersJ
author_rank: Frequent Contributor
timestamp: February 17, 2016, 12:14:50 pm
content: It never ocurred to me that the user interface would allow me to exceed the specifications.Next time I will read the manual first, then ask.Thank you for pointing out my mistake.

author: Richard Head
author_rank: Frequent Contributor
timestamp: February 18, 2016, 11:49:25 am
content: Also, if you enable the internal amplitude modulation the peak of the amplitude envelope cannot exceed the max level (+13dBm I think). I have a 56, a 57A and a 57B. Brutes, but nice.

author: mmagin
author_rank: Frequent Contributor
timestamp: February 18, 2016, 08:41:35 pm
content: A quick glance athttp://literature.cdn.keysight.com/litweb/pdf/5968-2704E.pdf?id=1000030211:epsg:dow:"Output power to drive high-level inputs For applications requiring high output power, the 8657A and B can overrange beyond the +13 dBm specified output level to >+16 dBm for most frequencies. "I assume the manual has more to say, but it sounds like that might be normal.
Siemens simodrive 611 infeed repair ends up in... more repairs - Page 1
Forum section: electronics / repair

author: EPTech
author_rank: Regular Contributor
timestamp: February 18, 2016, 10:45:15 am
content: Hello everyone,I have been contributing a little since my recent joining of this wonderful forum but this is my first official post, wow. Here it goes.I have repaired a simodrive 611 infeed module, which is essentially a 400VAC rectifier with regenerative capabilities. It had blown FET and power (fuse) resistor in the SMPS that powers the internal electronics. That one is working. The power relais is enabled and the DC link is charged. I enable the device making the enable input high. When I put the enable pulse high, I can hear the IGBT modules hissing and the DC link voltage lowers slightly. Is it normal that the device goes regenerative (a little bit) when it is idle? If so I consider it repaired.Now comes the funny part. I do not have a line filter or line reactor in the supply because I was not expecting it to put back something on the net. Anyway, the heating in the workshop went of and came back on. At first I thought it was random and tried again. I quickly realized I was putting high energetic noise on the net and immediately stopped testing. The heating is still working but as soon as I came inside the house I got a whiff of that "sweet" smell of burnt electronics. Slightly panicked I started checking all the electronics plugged in and opening up the defective ones. Turned out the pressure switch on the water pump and the furnace clock died. Amazingly all the cheap wall supplies survived. The defective supplies all had one thing in common. They are the MKT capacitor-resistor-zener or transorb-rectifier type. It seems these cannot handle high power harmonics. Can anyone confirm this? The capacitor is essentially a high pass filter so any spikes and harmonics just pass through, right?Anyway, I swapped some burnt out power resistors and blown zener diodes and all is well, except the poor contactless tooth brush charger, which is potted in shut. So, limited damage suffered but it could have been worse. Something semi-damaged may still break down later on but as long as I can repair it, I can live with it. I am off now. Have to go and buy a new tooth brush before the wife finds out. She will probably notice it's a new one but I can still say I have cleaned it right.

author: HAL-42b
author_rank: Frequent Contributor
timestamp: February 18, 2016, 11:42:59 am
content: I am amazed VFDs don't come with line reactors as standard.It should be mandatory IMO but that would triple the cost of every switch mode device out there.
IFR Aeroflex AN Series Spectrum Analyzer service info - Page 1
Forum section: electronics / repair

author: jry
author_rank: Newbie
timestamp: February 17, 2016, 01:06:27 pm
content: Anyone have the calibration passwords on these units ?The full service manual would be great as well.These would be the AN-920/930 ( CRT based ) and the AN-1820/30 ( LCD based ) modelsThanks
Kingston 64Gb microSD UHS-I card -  kaput ??? - Page 1
Forum section: electronics / repair

author: hgg
author_rank: Frequent Contributor
timestamp: February 16, 2016, 03:24:35 pm
content: Hi,I have been using for a week a brand new Kingston microSD UHS-I card in aChinese phone (...) and suddenly it stopped working. It looks like its a hardware problembecause it does not even show in the windows Device Manager when inserted in the reader.Readers work fine. I've tried two different card readers in two different PCs with same results.Do you know if there is an easy way to see if its a hardware failure?(I have an oscilloscope but no logic analyzer).Thanks.George.

author: wraper
author_rank: Unknown
timestamp: February 16, 2016, 03:55:37 pm
content: Are you sure it was really Kingston? Or did you buy it from China?

author: hgg
author_rank: Frequent Contributor
timestamp: February 16, 2016, 03:57:38 pm
content: 100% Kingston.Not from China...

author: wraper
author_rank: Unknown
timestamp: February 16, 2016, 08:37:39 pm
content: I would suggest to inspect if there are no crack in it, maybe try to bend it lightly to see if it is not broken already. About 70-80% of dead microSD cards I've seen were mechanically damaged. Usually they look normal at first glance, unless inspected with a great attention. Usually plastic on top has a crack in it, but the card is still in one piece because is held together by a thin PCB on the bottom side.

author: hgg
author_rank: Frequent Contributor
timestamp: February 16, 2016, 09:20:48 pm
content: I've just checked it with a microscope just in case, but its perfectly fine.No sign of stress on the case.Anyway, I guess I would have to return it back for a replacement.Is it possible that the phone damaged the card ?
used surge protectors - Page 1
Forum section: electronics / repair

author: Vgkid
author_rank: Super Contributor
timestamp: February 07, 2016, 03:37:49 am
content: I have a option of getting a used isobar either for free or cheaply. Since it is used in working condition( but unknown amount of hours are on it). What would need to be replaced, or should I use it directly. Might be an isobar ultra 12.Or should i just skip the idea, my current set of phillips are to finicky with the safety shutters.

author: sarepairman2
author_rank: Frequent Contributor
timestamp: February 07, 2016, 04:18:32 am
content: I think the MOV bank is the thing most likely to get worn down.

author: Vgkid
author_rank: Super Contributor
timestamp: February 07, 2016, 05:49:05 pm
content: Thanks, thats what i figured.

author: Kbeistline
author_rank: Newbie
timestamp: February 16, 2016, 01:15:39 am
content: As I understand the theory of Metal Oxide Varistor's (aka. fused resistor). As a circuit is powered the initial voltage spike causes the crystalline structure to heat up and increase resistance thus reducing the current delivered to a load. As the voltage level equalizes the crystalline structure cools and recombines thus reducing its resistance and allows more current to flow. If the initial voltage spike is greater than the MOV's max rating it will fail. Depending on how massive the spike is, it can fail rather spectacularly! I have not read any specifics on their meantime to failure, but can attest to the weakening of the crystalline structure causing them to fuse open. Over time, repeated normal spikes will weaken the crystalline structure causing it to merely open circuit, thus providing a valuable load protection. In the case of a nearby lightening strike, even a brand new MOV will 'pop' and may or may not provide enough protection for a given load.*SAFETY-1st* Make sure you completely understand how lethal repairing mains powered equipment is before attempting any repairs.Just checked Mouser.com, lists MOV's priced between 50¢ - $5 USD.
Display problem - Page 1
Forum section: electronics / repair

author: EEVaditya
author_rank: Regular Contributor
timestamp: February 14, 2016, 03:48:17 pm
content: Hello,The seven segment displays(common anode) 4th,5th & 6th and 7th,8th &9th from right side are not showing the reading properly.the problem I am getting is each of the above mentioned displays are showing same reading.the displays are driven by IC's 7447 (SN74LS47N)EEPROM is D2732A-2 (DIP-24)the supply voltage is 5VDCWhat would be the problem? refer attached photo.

author: uncle_bob
author_rank: Unknown
timestamp: February 14, 2016, 09:16:54 pm
content: Quote from: EEVaditya on February 14, 2016, 03:48:17 pmHiWhat is the data on the input lines to the 7447's (pins 1 through 7) ?Bob

author: EEVaditya
author_rank: Regular Contributor
timestamp: February 15, 2016, 02:54:41 am
content: Hello,the data is in binary form, I dont have exact idea. but whenever I operate this pcb in machine it should display decimal readings but the problem is all the displays are changing simultaneously.for eg. it should show readings like 120,200,150 etc.but it is showing 777, 888 etc. please guide.thanks.

author: uncle_bob
author_rank: Unknown
timestamp: February 15, 2016, 03:37:14 am
content: HiI suspect that ahead of the 74LS47 chips there is something like a 74LS75 / 74LS77 that holds the data to drive the 74LS47. There are at least two dozen different chip types that could have been used. It is impossible to guess all of them. The chip (what ever it is) acts as a memory for the display. It keeps the digits from changing like crazy. That chip has some sort of signal into it that tells it when to grab the data. If that signal line is shorted high, the memory chip will pass all the data instead of holding it constant. On the 75 / 77 the line to look at is called the enable line. It should be going high and low. If it is high all the time, you will get the display showing nonsense.Bob
HP1740A and HP1741A - Page 1
Forum section: electronics / repair

author: SAUL BRITTO
author_rank: Frequent Contributor
timestamp: February 02, 2016, 12:12:59 am
content: Hi. Can anyone say me if the focus unit of HP1740A is the same as hp1741a?

author: oldway
author_rank: Super Contributor
timestamp: February 02, 2016, 11:09:19 am
content: You mean probably the HV/PSU/Zaxis unit.http://www.sphere.bc.ca/test/hp-parts/hpparts8.htmlNo they are different because HV voltage of the 1741A is lower.

author: SAUL BRITTO
author_rank: Frequent Contributor
timestamp: February 15, 2016, 01:23:43 am
content: Thank you Oldway