hybridfree/eevblog-posts huggingface dataset:
Focusrite scarlett 2i2 no sound on input and outputs - Page 1
Forum section: electronics / repair

author: dantee
author_rank: Newbie
timestamp: November 12, 2016, 05:41:15 am
content: Hello, I am new on the forum!. My name is Joaquin (I have 17 years) from Argentina.. I have a technical service with my dad here.Well. I want to repair my focusrite 2i2 scarlett, because after triying I can´t search the fault here. So I need help to get it and also learn more with this repair if is possible..The history is one day, after connect a xlr microphone on the 2nd input (with phantom power on), and after disconnect it, the halo leds of the inputs of the focusrite started flashing and later, after disconnect the focusrite from the pc and connect it again I not have sound anymore.. the focusrite is recognized on the pc but after playing anything with my guitar there is no sound on input and outputs and no lights flashing on the inputs. The sound card starts to heat up sometimes when I connect it by usb on my pc . [I have tried with other usb cables and other pcs]I have no more warranty because it has been more than a year that I have it here (2014). I have disarmed it and I have looked at some components but at a glance I do not see any components in bad condition.I have soldering station and other components such as tester for test components, etc.The support of focusrite told me only to buy a new interface but here in argentina is somewhat overpriced. and I dont want to leave this interface in this wayThank you if you could guide me in this repair. Thanks and regards. I await your answers.

author: DaJMasta
author_rank: Super Contributor
timestamp: November 12, 2016, 07:29:18 am
content: I think the "always start with voltages" rule holds true here, I would start by getting the multimeter, finding a good ground, and probing the supply rails to the opamps or other drivers for the inputs and outputs.If neither the inputs nor outputs work, it's not likely to be a failure of a single component in the signal paths, but it still could be a single power supply device (electro cap leaking, regulator burnout, blown fuse, etc.) or if you're especially unlucky - the power supply failure pushed a rail way above spec and burned out everything attached.... I'd say that's not likely though.If it's still talking to your PC and interacting with the drivers, I think that's a good sign. If you have a scope you can try to trace out the audio path if the power seems intact. Also make sure that you've ruled out input and output components and cables as the source of the problem - if you have only one mic, for example, make sure that it's not that the mic went bad and that it's actually the interface.Basically, it's time to start taking stock of the elements of what make it run and testing them for basic functionality.
QUAD 4C Pick and Place HHT - Page 1
Forum section: electronics / repair

author: ElkoShop
author_rank: Newbie
timestamp: October 31, 2016, 01:43:05 am
content: I have two QUAD machines, (DOS Controller) and cannot get the hand held to move the head on either machine.It will home the machine, and I can read/modify MOD codes.Is there a special sequence to key in for this?Thanks in advance,Steve

author: ElkoShop
author_rank: Newbie
timestamp: October 31, 2016, 09:08:57 pm
content: I have the sequence.Push "Pickup", "any number", "enter"Then use arrow keys. Add Ctrl for fast, Shift for medium speed.Thanks to Bob at Precision-Repairs for the help.Steve
Agilent/Keysight U1242A LCD contrast issue - Page 1
Forum section: electronics / repair

author: NilsRoe
author_rank: Newbie
timestamp: October 30, 2016, 01:40:26 pm
content: Hi,a colleague found a seemingly dead Agilent U1242A in the junk bin at work. It is still working, however the LCD is barely readable. The contrast is very weak, and it can only be read when holding it at the right angle. The backlight works fine. The LCD reads better with fresh batteries, thoug it is still barely legible.Is there a hidden contrast setting, a trimmer, or some component that is known to cause the issue? I have already tried cleaning up the LCD, the zebra strip and the contact pads on the PCB; to no avail. I do not have much spare time anymore to investigate these things, so if there's someone out there who has had a similar issue with a U1242A please let me know.Best regards,NilsRoe

author: MosherIV
author_rank: Super Contributor
timestamp: October 30, 2016, 01:53:40 pm
content: HiBefore you spend money, try holding up some polarized sun glasses to see if it improves the contrast.I found this utube video which explains why and possibly where to get replacement polarizing film.Good luck

author: NilsRoe
author_rank: Newbie
timestamp: October 30, 2016, 02:02:40 pm
content: I just took it apart again; the panel itself seems to be fine. I tested it with a coin cell battery, carefully running a finger along the zebra strip. All the segments turn on, very sharp and crisp. So I guess it has something to do with the main PCB.

author: NilsRoe
author_rank: Newbie
timestamp: October 30, 2016, 02:25:15 pm
content: I have measured some of the contact pads with my oscilloscope; I'm reading a fairly typical 3VAC square wave with some modulation. Do the contact srips break down after a while? I haven't seen this kind of failure before. The contact strip measures arount 1K Ohm from top to bottom, so it should be allright.
Laptop, LCD not working, VGA works, artifacts - Page 1
Forum section: electronics / repair

author: AndreyS
author_rank: Regular Contributor
timestamp: October 30, 2016, 10:56:25 am
content: My laptop now works only with external monitor and only in safe mode.What was happening:1) HP dv7-4045er laptop is great laptop but with awful cooling system design. I had to often (once per month) clear the heatsink. But I wasn't able to keep it always up.2) Sometimes I could see some wrong textures in some games. It happened not really often (rare I'd say).3) I haven't turned the laptop off for about 35 days. But I kept the load low, so that laptop's fan was quite.4) Last time when I had to move, I hibernated the laptop. When I woke it up, LCD backlight turned on, but LCD showed all black. I waited for few (3-5) minutes and turned it off (I don't remember how long I held power button).5) I unplug power cable, and plug it in. Then I turned the laptop on. This time LCD backlight didn't work. LCD didn't show anything.After all that happened I connected external monitor, windows 7 wasn't able to boot up successfully (it crashed on loading screen. On loading video drivers maybe?). I was able to boot up in safe mode. But there some visible artifacts on the screen.you can see horizontal blue'ish stripsArtifacts (as random black dots) was present in bios as well.My question is: Is that really a fault of GPU/video memory or LCD connection?The outcome of the answer affects whether I:1) go to repair center, and get unreliable reballing or if I have a luck brand new GPU or2) buy the whole motherboard from China (they state that mb is fully tested and 100% working)PS: I think that GPU is the cause, and I am more inclined to buy the mb. But I'm alone with my mind at the moment, unconfident.

author: singapol
author_rank: Frequent Contributor
timestamp: October 30, 2016, 11:53:35 am
content: If it only boots up in safe mode it means windows has problems.You can boot up using debug mode why it runs ilne by line instructions and it will stop once it encounters the problem driver.If it's the video driver only you will know. If it is hardware problem then don't waste time repairing you will not like it afterv it is repaired and since this was introduced in 2010 it's time for a new laptop.

author: AndreyS
author_rank: Regular Contributor
timestamp: October 30, 2016, 12:39:36 pm
content: Quote from: singapol on October 30, 2016, 11:53:35 amI'd like to get a new laptop, but unfortunately I can't afford nice one at the moment. And the crappy laptop, I don't want it.Want to add, CPU doesn't have integrated GPU circuitry, and I had rarely this:And my PC froze when I tried to hibernate it while flashplayer plugin was in the RAM (with any browser).I ran debug mode, and it is indeed caused by ati driver atikmpag.sys:Dots are nicely visible here.Thank you man, I might definitely go for new mb.

author: wraper
author_rank: Unknown
timestamp: October 30, 2016, 12:48:00 pm
content: Most likely either GPU or VRAM is faulty.
Agilent E4425B with TBR board ref 10Mhz faulty - Page 1
Forum section: electronics / repair

author: Daxxin
author_rank: Regular Contributor
timestamp: October 30, 2016, 06:30:06 am
content: Hi , bought from ebay opened the module board 4 smd components was lost connection desoldered now have cleaned the boardcan please help to identufy this missing components ? the greys looks resistors 2,16 kohm (the first pic i found over internet)all 806 smd size?
Mystery SMD Part Identification - Page 1
Forum section: electronics / repair

author: alphablu
author_rank: Newbie
timestamp: October 30, 2016, 04:04:07 am
content: Hello all, I'm working to revive an expensive piece of network equipment and ive discovered the fault is a short in an SMD component that i have been completely unable to identify. I wondered if maybe someone might recognize this or know a little more about the markings.Its a power handling component of some kind, it has markings on it as follows:MPDJ86321188Attached is a photo of its front and back. any tips would be greatly appreciated!

author: singapol
author_rank: Frequent Contributor
timestamp: October 30, 2016, 04:44:19 am
content: I think this part is obsolete only the QFN package is available however you need to determine which one (current rating) and make adapter but don't know if this is pin compatible to your old one.http://www.mouser.com/Search/Refine.aspx?N=4292703013&Keyword=MPQ8632http://www.monolithicpower.com/Products/Product-Category/Static

author: alphablu
author_rank: Newbie
timestamp: October 30, 2016, 05:04:07 am
content: Oh i thought MPQ8632 might be related, i think i will try contacting the maker and see if i can get a confirmation from them. the pads on the board that i can identify appear to match MPQ8632's datasheet but im not certain about most of the 8 small ones on the side. Thanks for the help!
duplicated post please delete admin! - Page 1
Forum section: electronics / repair

author: Simon Spiers
author_rank: Regular Contributor
timestamp: October 17, 2016, 09:08:55 am
content: Hi all, wonder if you can help>I have just moved my 8568a from one side of the workshop to the other and now it has a problem.When the unit has been on for a while the CRT starts to show scrambled characters and the graticule seems to vanish.I have been over both units cleaning edge connectors and checking ESR of the tant caps but still no joy,It also shows the check instrument 1 led one this fault starts. Which is instrument 1?The actual waveform displayed looks un corrupted, so I am guessing the fault must lie in the display units character generation section?Any ideas please.Simon

author: Simon Spiers
author_rank: Regular Contributor
timestamp: October 28, 2016, 07:15:00 pm
content: The problen that seemed to vanish with the covers off is now back again once i put the instrument togetherAnother odd thing i descovered is than when recall 8 or 9 is rrequested you even loose the waveform info.This suggests a rom corruption an only recall 8 or 9 have this effect.Looking for spares if anyone can help.
Uni-T UT71A - capacity - Page 1
Forum section: electronics / repair

author: Horus92
author_rank: Newbie
timestamp: November 01, 2016, 08:07:41 am
content: Hello!I'm newby on the forum. I asked already in german forums, but I found so far no solution for my problem.I have bought a multimeter UT71A UniT on Ebay (Condition: new).Now I have found with the first measurements of the capacity that this does not function (it shows only 0.00000 F). I have of course taken the polarity of electrolytic capacitors.The capacitors are new (400V, 3.3 uF). I wait a long time, but nothing measurement. Also other capacitors were not working.The batteries of the multimeter are replaced.I opened the multimeter gently and i see a black wires with one end loose. In pictures fromthe board on the web, it does not exists.What is the purpose of the wire? Where is one ran the loose end.Does anyone have a similar mistake on his multimeter once before. Why can I not measure capacity?Can someone help me?Best regards, Horus92!

author: Horus92
author_rank: Newbie
timestamp: November 01, 2016, 02:17:09 pm
content: I found out that the Voltcraft 940 is the same as the UT71. In the appendix is ??the circuit diagram.Which part of the circuit is for capacity measurement? What should I consider?

author: Wytnucls
author_rank: Super Contributor
timestamp: November 01, 2016, 03:16:11 pm
content: I think your IC is the Cyrustek ES51922.If that is the case, check components and traces to pins 46, 47, 48 and 49.http://www.cyrustek.com.tw/product-1.htm

author: Monkeh
author_rank: Super Contributor
timestamp: November 01, 2016, 03:22:23 pm
content: Your meter is faulty, you bought it new. Get a refund.

author: retiredcaps
author_rank: Super Contributor
timestamp: November 01, 2016, 04:31:58 pm
content: Quote from: Horus92 on November 01, 2016, 08:07:41 amUsually these bodge wires are found on CEM Instruments meters. Uni-T meters do have bodges in the form of stacked SMDcomponents, but I haven't seen one with a wire especially one that goes nowhere. It is like someone used the bodge wire to fix something, but didn't do a very good job of soldering and shipping/handling caused the package to be moved and the wire to fall off?If you bought it new, I agree you should return it. Hopefully, shipping costs won't exceed the cost of the meter.

author: Horus92
author_rank: Newbie
timestamp: November 02, 2016, 03:51:44 pm
content: I found with the continuity tester, that the wire is connect the emitter from Q4 with the resistance R22. The Resistance is connect with Pin18 (OHV).The emitter from Q3 is the GND.I think it is vice versa on the circuit diagram.

author: WackyGerman
author_rank: Regular Contributor
timestamp: November 02, 2016, 06:55:42 pm
content: I see a spot next to Q4 and the bodge wire ? Is that solder ? Then it shorts two traces . You should remove that

author: carl_lab
author_rank: Frequent Contributor
timestamp: November 03, 2016, 01:19:26 pm
content: Gib den Murks zurück...
HP34401a screen repair - Page 1
Forum section: electronics / repair

author: sabahan
author_rank: Newbie
timestamp: October 27, 2016, 07:44:54 am
content: I bought a worn HP34401a with the display not displayed in full,the florescent some a not lid,I manage to get a replacement from eBay but how to I remove the old one from the meter,I read the instruction online ,the instruction just mention remove the screen but did not mention how,anyone have experience?please help

author: HighVoltage
author_rank: Super Contributor
timestamp: October 27, 2016, 07:49:35 am
content: Welcome to the forumDownload the 34401A service guide. On page 151 you will find an illustration of how to remove the front panel. Once you have removed the front panel, the rest is almost self explanatory to exchange the front panel PCB.

author: bitseeker
author_rank: Super Contributor
timestamp: October 28, 2016, 12:56:11 am
content: Hi sabahan,Welcome to the forum. Did you buy a replacement front panel PCB, on which a VFD module is already mounted, or just the VFD module (i.e., only the glass display)?When you say "remove the screen" are you referring to (1) removing the front panel from the chassis, (2) removing the front panel PCB from the front panel, or (3) removing the VFD module from the front panel PCB?

author: coldframe
author_rank: Regular Contributor
timestamp: October 28, 2016, 02:17:34 am
content: Hello sabahanVFD(Vacuum Fluorescent Display) is irrepairable part.Replace, For now this is the best way to goHave a read of this articleVFD display for HP 34401a multimeter wantedhttps://www.eevblog.com/forum/buysellwanted/vfd-display-for-hp-34401a-multimeter-wanted/msg197353/#msg197353coldframe.

author: BFX
author_rank: Frequent Contributor
timestamp: October 28, 2016, 08:28:12 am
content: Replace:http://www.ebay.com/itm/HP-AGILENT-34401A-Display-NEW-/151840490023

author: eb4eqa
author_rank: Regular Contributor
timestamp: October 28, 2016, 01:45:32 pm
content: That VFD module from eBay does work and it is new, but it is not original. I've installed one and it is not nearly as bright as the original one. Only way to go if you have a severely dim one or if do not have one at all...Roberto EB4EQA
Torn off mini USB connector - Page 1
Forum section: electronics / repair

author: JackM
author_rank: Regular Contributor
timestamp: October 22, 2016, 07:55:26 pm
content: How salvageable is this PCB with a torn off mini USB connector? This is the PCB from a Samsung SE-208 external optical drive, and from what I can tell it has suffered a fall and the removable USB cable connection took the brunt of it. They really need to be putting extra epoxy on these surface mount USB connectors. The pads have been ripped right off but I wanted to know if it was even worth trying to repair.

author: tautech
author_rank: Super Contributor
timestamp: October 22, 2016, 08:04:43 pm
content: Mmm, there's misuse or abuse that no manufacturer can account for.That it ripped all the pads off indicates (to me) that it was pretty well secured.I repaired the same uUSB socket that had ripped off on a drawing tablet....same cause, but the pads were still intact.Good luck but for something like that and for the time you'd spend on it....well no, bin it.

author: ataradov
author_rank: Super Contributor
timestamp: October 23, 2016, 01:06:37 am
content: Looks perfectly repairable. It all depends on your skill.That DVD thing costs $60 new, so it is not worth paying someone for repair, but would be a good chance to test and improve your skills.

author: mikerj
author_rank: Super Contributor
timestamp: October 26, 2016, 10:09:49 am
content: Quote from: tautech on October 22, 2016, 08:04:43 pmSecured as well as any surface mount micro USB connector, i.e. not very well at all. Surface mounting the data/power connections is fine, but the mounting tags should always be through hole whenever possible.
Keurig Power Supply Troubleshooting - Page 1
Forum section: electronics / repair

author: wilheldp
author_rank: Regular Contributor
timestamp: October 24, 2016, 11:14:42 pm
content: My neighbor likes to give me stuff that has died on him to see if I can fix it. Yesterday, he handed me a Keurig B60 coffee maker. I told him that they were pretty complex, and probably wouldn't be able to fix it, but he said that the problem was just that it wouldn't turn on. That gave me hope that it would be something simple that I'd be able to fix pretty quick.I got the thing apart today and I have 2 initial thoughts:1. Holy crap this thing is a PITA to take apart. It took about 20 screws and a bunch of stiff plastic clips to take the housing apart, and I had to cut 3 ground conductors that were pop-riveted to the bottom plate of the housing just to disassemble it.2. This thing is needlessly complex. It seriously looks like a Rube Goldberg machine to make coffee. No way a coffee maker needs this many moving parts.Anyway, I finally got access to the noise filter board and power supply/distribution board. I have continuity from the plug blades all the way through to the output of the power filter board, but when I power it up, I get ~50 mV across line and neutral. I removed the primary connector from the transformer, so I don't think it is a failed transformer (common Keurig problem) causing the problem.The noise filter board just has 2 inductors, an X2 capacitor, discharge capacitor, decoupling caps, a diode, and a MOV. I desoldered the MOV, and got identical readings. I plugged it in to a Kill-A-Watt, and I'm putting 123 VAC into the board, but it is drawing 0A and 0W. Any idea what might be causing this issue?

author: wilheldp
author_rank: Regular Contributor
timestamp: October 25, 2016, 09:26:39 pm
content: Figured it out, but found another problem. It turned out to just be an open circuit across the primary on the transformer, which is what I thought it was to begin with. But the reason I didn't figure that out before is because my EEVBlog meter isn't very useful on mains voltage. It was reading 50 mV across the mains, even when I hooked it directly to the mains. I re-tested everything with my Agilent meter, and mains was getting where it was supposed to. I bodged in a 14.5 V transformer I had laying around, and the Keurig fired right up.

author: electr_peter
author_rank: Unknown
timestamp: October 25, 2016, 09:56:05 pm
content: Have you used "AC" voltage setting on DMM to measure mains? If DC voltage mode was used, you could see only small DC voltage, but not full AC mains.

author: wilheldp
author_rank: Regular Contributor
timestamp: October 25, 2016, 10:27:34 pm
content: Quote from: electr_peter on October 25, 2016, 09:56:05 pmI just figured it out. I thought that the "V" setting one click clockwise from "off" was the auto-sensing voltage range, but now I see that it is one click counter-clockwise. I had it set to measure VDC instead of VAC.
Repair of Fluke 6060B RF signal generator - Page 1
Forum section: electronics / repair

author: TheDefpom
author_rank: Frequent Contributor
timestamp: October 30, 2016, 11:48:57 pm
content: Hi all, I thought I would just share my repair videos here for this unit, in case anyone is interested.https://youtu.be/0aMK52UX1AMThere are 5 videos in total, this is the first in the series.

author: wn1fju
author_rank: Frequent Contributor
timestamp: October 31, 2016, 01:46:19 am
content: Nice videos. Fortunately, mine was a bit easier to diagnose and repair. It threw errors 5 and 13 (left and right displays), but a first look with the spectrum analyzer at 100 MHz showed everything was working properly. It wasn't until I hit >245 MHz that I saw the problem - harmonics that were only 3 dB down from the fundamental and an output that didn't track the amplitude setting. Plus the modulation looked overdriven. I simply took a scope and probed my way along the signal path until the waveform first looked distorted. On the output PCA, there is a three-stage 20 dB amplifier. The 150 ohm collector resistor on the second amplifier transistor changed value to 750 ohms. This starved the transistor of gain and the ALC circuit tried to compensate by overdriving the hell out of the signal before it got to this amplifier. Anyway, pretty amazing that the entire 6060B was brought to its knees by a single lousy resistor!

author: TheDefpom
author_rank: Frequent Contributor
timestamp: October 31, 2016, 02:05:49 am
content: I certainly enjoy a good fault finding session, but this was a bit longer to resolve than I wanted!If I had stopped working on it as soon as I found the faulty MC10131P it would of been better, as I spent a lot of time trying to trace the 20MHz offset fault, originally thinking it was a separate problem, once I realized it was likely connected I stopped working on it until the new part arrived.
LT8310 model for LTspice / SwitcherCAD? - Page 1
Forum section: electronics / repair

author: carl_lab
author_rank: Frequent Contributor
timestamp: October 26, 2016, 02:16:05 pm
content: I tried to open this demo circuit for LTspice from LT website:LT8310/LT1431 Demo Circuit - 81 Watt Isolated Nonsynchronous Forward Converter with Opto Feedback (10.8-26.4V to 54V @ 1.5A)http://www.linear.com/docs/46074It doesn't open completely but displays this message:Anybody willing to try it for me?Where can I find this sybol and how can I embed it into LTspice?

author: razberik
author_rank: Frequent Contributor
timestamp: October 26, 2016, 02:24:35 pm
content: No problem here. I open it directly in LTspice 17.

author: carl_lab
author_rank: Frequent Contributor
timestamp: October 26, 2016, 02:32:36 pm
content: OK, thank you.After installing latest LTspice version, it works!
TTP223 touch sensors self-triggering bug - Page 1
Forum section: electronics / repair

author: drasik
author_rank: Newbie
timestamp: October 25, 2016, 11:29:46 am
content: I have three TTP223 touch sensors connected to a power source (only VCC and GND are connected).I intentionally didn't connect I/O pin to Arduino because I suspected that it could cause the problem (trigger the sensor by accidentally sending current to the I/O pin). One of the sensors gets triggered and starts blinking, please see the video:https://www.dropbox.com/s/y0eeg959fybolfz/IMG_0495.MOV?dl=0I fail to reproduce this bug consistently and don't know what causes it. I've noticed the following:1. It happens only on the 1st and/or the 2nd sensor only if they are both connected (but after switching sensors and then assembling this same setup - sometimes this bug disappeared).2. Thought they were too close together and were triggering each other but I tried putting other sensors even closer and it didn't happen.I would be very grateful for any ideas on why this is happening, thanks in advance!
VFD aging or faulty support components? - Page 1
Forum section: electronics / repair

author: sanchaz12
author_rank: Regular Contributor
timestamp: October 23, 2016, 11:49:56 am
content: Hi all,Recently I got a Sony MiniDisc deck MDS-JE520 to see how this system works. It works very well for its age (1998), but the VFD is quite dim and lit uneven. Other examples on eBay of the same model show a nice and bright VFD. I do not know much about driving VFD's in general, but what I do know is that VFD's can age and lose their ability to display bright segments over time. I cleaned the screen bezel and VFD, this took the 'haze' that was visible away. It looks crisp now but not much improvement in terms of brightness.Now the interesting thing for me is the uneven illumination. Along every horizontal filament the segments behind the filament are noticeably darker than the segments not 'covered' by the filaments. Is this (also) a typical sign of wear/age? I checked the main capacitors and measured the voltage test points against the values provided in the service manual and everything seems fine.Looking trough the service menu I found timers for total play and record times. These total up to about 8400 hours of usage.Is this considered as normal wear and aging or could there be a fault in the VFD driver or some other components?If anyone is interested in the service manual, you can find it here (see page 63-66):http://www.minidisc.org/manuals/sony_mdsje520_service.pdf

author: bktemp
author_rank: Super Contributor
timestamp: October 23, 2016, 12:03:29 pm
content: VFDs show two different types of failure modes:Either the cathode (filament) fails (its electron emitting layer), often due to a wrong (too low) filament voltage, or the phosphors on the segments are worn out.In your case it looks like the phosphors on the segments are worn out, because the area below the filament wires is darker. Because they are closer to the filament wires, they get the highest current.There is probably not much you can do without changing the display.

author: sanchaz12
author_rank: Regular Contributor
timestamp: October 23, 2016, 09:09:04 pm
content: Quote from: bktemp on October 23, 2016, 12:03:29 pmThank you, that was exactly what I needed to know.It's pretty hard finding a exact replacement, and trying to 'rejuvenate' the VFD will not work in this case I think. Better to leave it alone as it still works. Just one more question. By 'too low' filament voltage I assume you mean the voltage is too much on the negative side. Is that correct?
Keithley 2000 transformer humming - Page 1
Forum section: electronics / repair

author: kloetpatra
author_rank: Regular Contributor
timestamp: October 22, 2016, 06:04:11 pm
content: Hi, I recently bought a Keithley 2000. When powered I noticed that the transformer is humming very loud. I wanted to know if I can reduce the humming... maybe be adding some rubber buffer between the transformer and the case?Or do you even think replacing the transformer by a switching power supply can be done without adding too much noise?

author: Kleinstein
author_rank: Super Contributor
timestamp: October 22, 2016, 06:39:48 pm
content: Some noise from the transformer is normal, but usually not very much. The first thing would be to check the mains voltage setting. If set for to low a voltage, it can hum loud but also burn after some time.Also a partially broken rectifier (one diode open) could cause extra hum. Another cause might be excess filter capacitance (e.g someone changing the filter caps to larger values).Changing to a switched mode supply is not a good idea. It will add extra noise, unless you get a really special low noise one. Especially common mode signals are a really pain to get rid of.Adding rubber buffers ans sometimes extra glue could help against to much hum.

author: Andreas
author_rank: Super Contributor
timestamp: October 22, 2016, 07:02:48 pm
content: And you are shure that there is no dimmer active in the room?With best regardsAndreas

author: kloetpatra
author_rank: Regular Contributor
timestamp: October 22, 2016, 09:10:12 pm
content: Yes the humming comes definitely from the transformer. I took everything apart and removed it from the case. Then the humming is gone. But as soon as it's screwed to the case, even with some rubber buffer (picture 1), it still humms as loud as a dimmer would do. Maybe I need to add some rubber washers too. The rectifiers and caps seem to be ok.Now I noticed that the VFD is making more annoying crackling noise. It sounds like a constant arcing high voltage. I can't identify if it comes from the display or from those VFD driver ICs (picture 2).

author: Rbastler
author_rank: Frequent Contributor
timestamp: October 22, 2016, 09:25:36 pm
content: Check the main filter cap after the rectifier. I bought a HP3478A that hummed more than it should (I had two at the time). After replacing the filter cap of the main power rail, the hum was much lower in amplitude.It might be just a bad cap in your Keithley 2000 too. Just from looking at the cap, the failure isn't always obvious. In my case it kinda was, because the cap had a old style package.
Part needed for Fluke 87-III repair - Page 1
Forum section: electronics / repair

author: cowboy
author_rank: Newbie
timestamp: October 21, 2016, 06:13:58 am
content: I am repairing my Fluke 87-III and I have encountered a part I need that is no longer availableIt is the grey seal around the entire perimeter of the meter's case, if anyone has one, even used is fine.It fits on to the bottom case half, so an 87-III bottom case half would work as well, if seal is still present.I can paypal you.
NVRAM new but with data!, it's possible? (Mouser) - Page 1
Forum section: electronics / repair

author: klaus11
author_rank: Unknown
timestamp: October 23, 2016, 06:55:33 pm
content: I placed an order to Mouser, including NVRAM DS1220AD. My Surprise is that is dated 2014 and has written data.My question is a new NVRAM, or Mouser me scammed.I've never bought NVRAMS new only ebay, so I wonder.Opinions are welcome.

author: ataradov
author_rank: Super Contributor
timestamp: October 23, 2016, 07:03:29 pm
content: What kind of data? I would assume that devices are tested before leaving the factory, so if it looks like test patterns, then I think it is fine.Also, SRAM is "initialized" to random values at power up, so when they assemble this, original content of the RAM will be random noise. If they don't explicitly erase it to some known value, then you get that random noise.And I don't see any notes on the original contents in the datasheet, so it can be anything,

author: wn1fju
author_rank: Frequent Contributor
timestamp: October 23, 2016, 07:31:19 pm
content: I just received a DS1225AD from Mouser a couple of days ago. Mine had a 2016 date code and also had "data" when I read it. Nothing to worry about.

author: SeanB
author_rank: Super Contributor
timestamp: October 23, 2016, 07:33:45 pm
content: RAM chips will always power on to some state, not all zero or one ( that is the default for EPROM and EEPROM, as they are erased during manufacture as part of the testing for QC), and the actual state of each cell will vary, though you will get blocks that power on to a particular value or just random values.The NVRAM chips as manufactured have a non resettable freshness bit in there, that is set to power off the internal RAM until the first power up of the unit in use, which then enables the on board supply to the memory, and this is then only reset when the battery is totally flat again. This is to give the best storage life, as then the minute drain from the RAM chip is not applied to the coin cell there.If it has valid data ( readable strings of data in locations, increasing numbers in a sequence) then it probably was a chip that had full QC done on it in test, or a return, though if it was still in the original unopened pack it would be hard to see if it was a return.

author: klaus11
author_rank: Unknown
timestamp: October 23, 2016, 07:42:41 pm
content: Captura NVRAMby

author: ataradov
author_rank: Super Contributor
timestamp: October 23, 2016, 07:45:15 pm
content: That looks pretty random, normal for SRAM.BTW, SRAM in the microcontrollers will have similar "data" on power up.
Stone file - Page 1
Forum section: electronics / repair

author: akis
author_rank: Frequent Contributor
timestamp: October 19, 2016, 07:42:57 am
content: I have had for a while a rectangular, stone-like file, it is roughly 10cm long, and about 6mm each side square, it has snapped in two pieces, I am attaching a photo of the smaller piece (have probably lost the other), it is very fine and have used it to gently sand down bits and pieces like say epoxy coated copper wires. I would like to buy a new one, but I cannot find it I do not even know what it's called.

author: RoGeorge
author_rank: Super Contributor
timestamp: October 19, 2016, 07:54:48 am
content: It looks like a knife sharpener stone.

author: tautech
author_rank: Super Contributor
timestamp: October 19, 2016, 07:57:03 am
content: It's just an oilstone, in your case one that's commonly used on small cutting edge tools like loppers, secateurs etc.Here's a google search with all you need to know and some sources.https://www.google.co.nz/webhp?sourceid=chrome-instant&ion=1&espv=2&ie=UTF-8#q=oil%20stones%20tool%20sharpening

author: Andy Watson
author_rank: Super Contributor
timestamp: October 19, 2016, 09:45:14 am
content: I think this depends on your locale and trade. I know them as slip-stones but I have also heard them being called die-maker stones, Norton stones and (perhaps wrongly) Emery sticks.

author: Mickster
author_rank: Contributor
timestamp: October 19, 2016, 11:26:51 pm
content: Kinda reminds me of a cylinder hone insert. (Cylinder hones are used to de-glaze engine blocks when replacing piston rings)Take a look here and see if these inserts are possibly what you have:https://www.summitracing.com/search/part-type/cylinder-hone-replacement-componentsRegards.

author: eKretz
author_rank: Frequent Contributor
timestamp: October 21, 2016, 08:21:06 am
content: The oil stone guess is correct. You can see written on the side of the stone "SiC Fin" - this is silicon carbide - fine grade (that isn't very meaningful, fine can be graded differently between different makers), a common synthetic honing stone abrasive.Most commonly these are referred to as slip stones. Try a company called Gesswein - they make some very nice ones.
Wavetek 114 Sweep Generator, Exploded Caps - Page 1
Forum section: electronics / repair

author: Cyberdragon
author_rank: Super Contributor
timestamp: October 20, 2016, 07:31:22 pm
content: I heard rattling bits inside. I thought it was just bits of dirt, but nope. The rattling bits were a dead moth (EW!) and the remains of two capacitors (UH OH!).The caps were Richy brand 100uF 15V. Are Richy caps just crap or is there a serious problem? (I'll get pics once I have it all apart)The attenuator control is also stuck, but I have to find the cause of the burned out caps first.EDIT: Finding more exploded caps! This is getting grim!

author: radioFlash
author_rank: Regular Contributor
timestamp: October 21, 2016, 02:20:04 am
content: That looks similar to the VCG board of my Wavetek 116. Attached is a photo and schematic for the 116. You should check the power supply voltages.

author: singapol
author_rank: Frequent Contributor
timestamp: October 21, 2016, 04:08:33 am
content: If you look at the schematic title block it's dated late 60's almost 50 years old what do you expect?Given Richy brand is not one of the premium brands it has served it's useful life. As a matter of fact learned articles have said the max. max. life span of an electrolytic cap is between 20 -28 years. although there are cases where caps over 50 yrs. are still running in equipment but that's not the reality or norm. Remember the oxide layer (insulation ) is only molecule thick...how small is it? Once the electrolyte dries up it's goodbye cap.
Please Identify This... Transformer? - Page 1
Forum section: electronics / repair

author: ruthsarian
author_rank: Contributor
timestamp: October 20, 2016, 04:16:39 am
content: Attached are photos of a component from a handheld Tandy Electronic II (American) football game. It's a circular component, about 11mm wide. It should have 9 pins (1 pin has come off). The pins are about 2mm apart. I believe it's made of ferrite with wire wrapping around the core. The PCB marks this component as "T1". So with all that I'm assuming it's a transformer of some kind dating to somewhere around 1980 (based on date codes on the chips on the board it came from). The game is powered by 4 AA batteries and uses around 80 surface mount LEDs as the display for the game.Is it a transformer? What kind of transformer or what kind of package or form would you call it? Is there a replacement that matches that footprint that I could find today?Thanks

author: Ian.M
author_rank: Super Contributor
timestamp: October 20, 2016, 04:50:16 am
content: Its a HF transformer, probably from a switching supply circuit.. It would have been custom wound for the application. Replacement will be near impossible - even if you do a lot of work to determine all its parameters, you then have to try to match the core with something modern, wind a replacement and probably make a converter board for the pinout. Instead, repair it. Epoxy in a replacement pin and either extend any broken wires that led to that pin, or if the wire end is deeply buried under the winding, unwind it carefully noting wire positions, connections, gages and turn counts and rewind it with new wire to the same spec.

author: ruthsarian
author_rank: Contributor
timestamp: October 20, 2016, 12:58:05 pm
content: Quote from: Ian.M on October 20, 2016, 04:50:16 amThat is what I was afraid of. The broken wire is accessible so I'll give fixing it a go. Thanks.

author: cvanc
author_rank: Frequent Contributor
timestamp: October 20, 2016, 04:27:38 pm
content: Quote from: ruthsarian on October 20, 2016, 12:58:05 pmDefinitely the good way to go, assuming you can access that wire end.Lacking that you would probably need to find the exact same model on eBay or somesuch and use it as an organ donor. Unless it works, of course - then just use that one
HP 8568A Cal output adjustment  - Page 1
Forum section: electronics / repair

author: Simon Spiers
author_rank: Regular Contributor
timestamp: October 20, 2016, 06:43:13 am
content: Hi again another 8568a related question.When i used to cal the -10dBm level using rcl 8 from the nvr i could adjust the level with the preset on the front panel .My latest attempt has failed to show any shift in the level which is now off the top of the scree .What i need to know is this.Does the trimmer adjust the input gain of the generator or Cal level?It looks like its tied to the a16 board?
Anyone recognize this repair device  - Page 1
Forum section: electronics / repair

author: soptea
author_rank: Newbie
timestamp: October 19, 2016, 07:14:01 pm
content: Found this on an advertisement site presented as an robotic / automatic repair device .Could anyone give some more info please ?Thanks !

author: jkf1000
author_rank: Regular Contributor
timestamp: October 19, 2016, 11:11:25 pm
content: Have you tried asking the seller/advertiser if they had any more information available? Karl

author: Shock
author_rank: Super Contributor
timestamp: October 20, 2016, 02:13:36 am
content: Logo in the background says CLE Baltic.

author: MK14
author_rank: Super Contributor
timestamp: October 20, 2016, 02:33:15 am
content: It could be this one:http://unitechnologies.com/en/product/robot-de-table-tr300/
Tektronix 2445a screen problem - Page 1
Forum section: electronics / repair

author: casteliano
author_rank: Newbie
timestamp: October 16, 2016, 06:06:51 pm
content: I recently bought this scope as not working a sure enough the screen was blank on power up, however after adjusting grid bias a bright dot and very small text? could be seen. Everything elese appears to be working correctly. Any help would be appreciated.

author: singapol
author_rank: Frequent Contributor
timestamp: October 16, 2016, 06:49:38 pm
content: Welcome,2445A may need capacitor replacement but note there are some surfacemount electrolytic caps,see link below.http://bradthx.blogspot.sg/2014/01/tektronix-2445b-capacitor-replacement.htmlMay be do a scope self test by reading user manual and finally if need repair ..the service manual.Troublshooting oscilloscope:www.sphere.bc.ca/test/tek-parts/troubleshooting-scopes.pdf2445A user manual:http://www-3.unipv.it/lde/strumentazione_strum_banco/oscilloscopio.pdf2445A service manual : 85Mb file:330pg.http://elektrotanya.com/tektronix_2445a_2455a_sm.pdf/download.html

author: Skimask
author_rank: Super Contributor
timestamp: October 17, 2016, 02:54:43 am
content: Do a search for the 2445 (2465, 2445a, 2445b, 2465a, 2465b, and so on), specifically look at U800 and the cooling fan. Fan goes out, U800 overheats, only half the screen works. There's procedures out there for figuring out if U800 is bad. Not a difficult replacement by any stretch. Harder to find the IC. Mine cost somewhere around $150 if I remember right. I also junked the stock fan and replaced it with a suitable sized squirrel cage fan in almost the same mounting holes pulling off the +15v rail. In addition, just to make sure U800 wouldn't overheat and fry again, I grab a couple of old 40mm PC cooling fans and a cheap 12v wall wart and velcro'd the whole works to the side of the case kinda pushing air in the general direction of U800.

author: casteliano
author_rank: Newbie
timestamp: October 19, 2016, 05:12:47 pm
content: Thanks! After replacing caps in the power supply the scope works great! Another great score from ebay.
GoPro Hero 4 NO POWER - Page 1
Forum section: electronics / repair

author: .0001centchips
author_rank: Newbie
timestamp: October 15, 2016, 01:11:22 am
content: Hi everyone,I have couple of GoPro Hero 4 motherboards that have no power, never been worked on. Looks brand spanking new..I have tried using a freeze spray and trying to find overheating components but no luck..Any suggestions or advice are appreciated!!Cheers

author: poot36
author_rank: Frequent Contributor
timestamp: October 17, 2016, 06:27:54 am
content: I would start by checking all the fuses and looking for hairline cracks in the circuit board next to any heavy or large components.
RCA RLDED5078A-D TV Weird Picture - Page 1
Forum section: electronics / repair

author: XMA
author_rank: Contributor
timestamp: October 13, 2016, 02:08:45 pm
content: The tv displays a picture but really weirdly, there is a line going through horizontally in the middle of the tv distorting the picture / bending it, and then there is a dark area on the bottom, the dark area seems to be a an inverted area of the display that is going out of the tv bounds, oh and as you can see the display is going out of the tv bounds also I've tested with other electronics but it's still there, also i had opened the tv to check for bad capacitors but nothing bad that looks bad, I've got a feeling it is a bad main board rather than the LCD logic board or the power supply. please help out as i first made a thread in BadCaps and no one made a reply and seemed to ignore me.

author: KK
author_rank: Regular Contributor
timestamp: October 14, 2016, 10:37:06 pm
content: Try other input jacks and see if the distortion follows (t-con board?) or if the distortion does not follow (main board?)

author: XMA
author_rank: Contributor
timestamp: October 15, 2016, 03:53:43 am
content: its the same on every port, i don't think it's the t-con board, because i went into service mode and was changing the view settings, that make your display go in or out, smaller or bigger and i could have not gotten bellow the black line for some reason

author: mij59
author_rank: Frequent Contributor
timestamp: October 15, 2016, 06:58:27 am
content: Could be a corrupted configuration, is there a reset to default in the service menu ?Same problem when using the tuner ?

author: XMA
author_rank: Contributor
timestamp: October 15, 2016, 07:55:50 am
content: yes there is a reset to default option. also I tried resetting it but it just goes back to like before with the picture out of the screen, and do you mean by tv tuner then I don't have one, I use HDMI and when i turn on the tv it shows the RCA logo with a white background in which you can see the center line, but the bottom dark spot is white with the background. and if go to the menu part of it gets displayed in the dark spot but inverted.

author: poot36
author_rank: Frequent Contributor
timestamp: October 17, 2016, 06:20:48 am
content: If the problem shows up on the osd (on screen display, ie the menus) then the problem is either tcon related or the hotbar flat flex connections to the panel are going bad. On some tv's there is a jumper to put the tcon board into a test mode (on some panels there is no jumper but a unused pin on the panels tcon board that you pull up to the tcons power supply through a 1K? resistor or down to ground through a 1K? resistor, find the panels data sheet for the correct pin and if it should be pulled high or low) that would eliminate the main board as been bad as well. Try and find a service manual for the tv if possible.
Hameg HM305 Osilliscope service Manual - Page 1
Forum section: electronics / repair

author: dean.kindleysides
author_rank: Newbie
timestamp: November 25, 2015, 11:34:13 am
content: Has anybody got service a manual forHameg 305 Not 305-2Nothing on Hameg website only user manual

author: dom0
author_rank: Super Contributor
timestamp: November 25, 2015, 04:15:01 pm
content: Ask Hameg support they have almost every manual dating back to the late 50s.

author: Pat Pending
author_rank: Regular Contributor
timestamp: November 27, 2015, 06:55:51 am
content: Servicemanual_Hameg_HM_305-2.pdf

author: DeanKindleysides
author_rank: Contributor
timestamp: November 28, 2015, 09:39:43 am
content: I have asked Hameg service department several times and they still have not repliedAnd I need the HM305 not the 305-2,

author: anotherlin
author_rank: Frequent Contributor
timestamp: November 30, 2015, 08:32:21 am
content: Last week, I emailed Hameg and they told me to email R&S support instead.So far, no answer.It is a pityHameg's support used to send service manual pdfs within 48h.

author: DeanKindleysides
author_rank: Contributor
timestamp: December 01, 2015, 09:13:10 am
content: I was told the same thing still waiting

author: DeanKindleysides
author_rank: Contributor
timestamp: December 08, 2015, 07:21:39 pm
content: Anybody got a manual or circuit diagrams before I give up and eBay it

author: tautech
author_rank: Super Contributor
timestamp: December 08, 2015, 07:27:34 pm
content: Quote from: DeanKindleysides on December 08, 2015, 07:21:39 pmIf you Google for "Servicemanual_Hameg_HM_305-2.pdf" from reply #2 you'll get:http://www.mikrocontroller.net/attachment/133545/Servicemanual_Hameg_HM_305-2.pdfEditIt's one of the best SM's I've ever seen available from the net.

author: oldway
author_rank: Super Contributor
timestamp: December 08, 2015, 07:31:54 pm
content: http://www.radiomuseum.org/r/hameg_oszilloskop_hm305hm_30.html

author: ostap
author_rank: Newbie
timestamp: August 25, 2016, 10:19:09 pm
content: Quote from: dean.kindleysides on November 25, 2015, 11:34:13 amhttps://drive.google.com/file/d/0Bz230ThydfRGNFh4SlRVeEh4bkU/view?usp=sharing

author: DeanKindleysides
author_rank: Contributor
timestamp: October 16, 2016, 09:03:43 am
content: All sorted now thanks