hybridfree/eevblog-posts huggingface dataset:
Identification of SMD part, possibly a voltage regulator - Page 1
Forum section: electronics / repair

author: obiwanjacobi
author_rank: Super Contributor
timestamp: June 12, 2017, 03:31:36 pm
content: I am repairing a Roland GI-10 Guitar MIDI Interface which does not turn on.The unit is supplied with a 9V adapter and my guess is someone put in a too high a voltage.I encountered a blown up C across the barrel socket input (which I removed) and the SMD part in question that did not output any voltage.The SMD (D20) part says: 'SC 5B'I first thought it would be a voltage regulator but the D20 designator does not make sense. A zener perhaps?Possibly the other regulators (?) Q3, Q4 and Q5 are shot also.Unfortunately I do not have a schematic.

author: Microcheap
author_rank: Frequent Contributor
timestamp: June 12, 2017, 04:06:47 pm
content: I'm not sure, but I made a quick search at:http://www.smdcode.com/en/smd/code/search/?q=scand got a result for a dc/dc convert from a japanese company called Torexhttps://www.torexsemi.com/file/xc6371/XC6371-XC6372.pdfApparently this midi interface is made in japan, so it might make sense.I hope this will be of some help.

author: obiwanjacobi
author_rank: Super Contributor
timestamp: June 12, 2017, 04:49:37 pm
content: Thank you, that does look plausible.However, in an attempt te reverse engineer the schematic from the PCB, I noticed that pin 3 (right most) on D20 is not connected.It does not seem to go anywhere. I have tried to beep-out all nearby traces - nothing. It is not a via either.So perhaps D20 is just a diode (to protect against reverse polarity)?

author: PA0PBZ
author_rank: Super Contributor
timestamp: June 12, 2017, 06:33:59 pm
content: Quote from: obiwanjacobi on June 12, 2017, 04:49:37 pmI guess it is, and 5B points to a double diode. Just connect pins 1 and 3 and see if it works?

author: JFJ
author_rank: Regular Contributor
timestamp: June 12, 2017, 07:54:39 pm
content: Quote from: obiwanjacobi on June 12, 2017, 03:31:36 pmAs the pin 3 pad isn't connected to anything else, it may just be a low forward voltage diode, e.g:http://www.mouser.com/ds/2/308/EN2985-D-462854.pdf

author: obiwanjacobi
author_rank: Super Contributor
timestamp: June 13, 2017, 03:08:23 pm
content: Because I already desoldered the SMD device, I measured with the DMM (diode mode) between all pins in both polarities.Non of the pins are connected at the moment, which leads me to conclude that indeed there is probably only a single diode in this package.If it were a double diode, I would expect the other one to remain intact.Thanks for all the suggestions.EDIT: Yep, that worked

author: obiwanjacobi
author_rank: Super Contributor
timestamp: June 14, 2017, 03:35:35 pm
content: I got part of the schematic and it IS an SB20!
Ideal CK70 Boiler PCB - Page 1
Forum section: electronics / repair

author: Lion_Tamer
author_rank: Contributor
timestamp: June 14, 2017, 10:29:56 am
content: Hi AllI have been repairing the control boards for this boiler after they were damaged by lighting, I have managed to get them going again but have an issue/question on this one that I can't understand.In the circuit below I don't understand what the 7805 voltage regulator is doing, I expected to get 5V between its output and ground but instead there is 8.2V as regulated by the zener diode.For info I have already replaced P1, Z2, U1, IC1, and the probe assembly containing the LM335 as these were damaged by the lightning, I have also replaced Z1, and Z4 and checked that all of the other resistors and capacitors test okay on a meter.Thank youJem

author: CJay
author_rank: Super Contributor
timestamp: June 14, 2017, 10:43:47 am
content: I *think* it's configured as a constant current source but I could be wrong, are you measuring output with respect to the circuit ground or the terminal on the 7805?

author: P90
author_rank: Frequent Contributor
timestamp: June 14, 2017, 10:46:25 am
content: yeah, are you probing ground at pin of 7805?

author: Lion_Tamer
author_rank: Contributor
timestamp: June 14, 2017, 01:09:01 pm
content: At the gnd pin of the 7805.Jem

author: CJay
author_rank: Super Contributor
timestamp: June 14, 2017, 01:40:37 pm
content: Quote from: Lion_Tamer on June 14, 2017, 01:09:01 pmOK, so first check your 7805, you've not mentioned which variant it is, some of the plastic ones (I.E. not TO-220) can have 'odd' pin assignments and if you've changed from one to another it's possible it's not fitted correctly but, as the gnd connecton of the device isn't connected to 0V I reckon it's being a current source and not configured to be a 5V regulator.
Identify this regulator IC - Page 1
Forum section: electronics / repair

author: james_s
author_rank: Super Contributor
timestamp: June 18, 2017, 07:22:59 pm
content: Few things are more irritating than numbers sanded off ICs. I'm trying to repair a multi-chemistry battery charger, Turnigy Reaktor aka Charsoon Antimatter aka iCharger 206b. It had several blown mosfets and at this point I suspect this control IC which I believe is a buck-boost regulator with synchronous rectification which drives a number of external power mosfets. It interfaces to a microcontroller that handles all of the charger functions but I know little about the overall circuit design. It's possible that the IC in question is nothing more than a mosfet driver with everything else handled by the microcontroller but I'm not sure. Unfortunately it's a rather dense PCB with black solder mask making it very difficult to reverse engineer although I'm tempted to xray it to make that task easier. I wouldn't bother except that I'm annoyed by the deliberate obfuscation and would like to figure out what this IC is. There are a number of adjacent pins bridged together which may provide some clues to narrow down the search but so far I've come up empty handed.
Fluke 95 ScopeMeter - Board Shorts? - Page 1
Forum section: electronics / repair

author: EHT
author_rank: Frequent Contributor
timestamp: June 12, 2017, 11:27:23 pm
content: This problem was trickier than it initially appeared. A key on the rubber membrane keypad wasn't working. This was the 'down' key. Not absolutely essential for operation but useful. I assumed this would be the conductive rubber on the keypad so i had finally got around to opening it up and checking. No obvious signs of wear or oxidisation. I cleaned it up a bit with IPA and put some more graphite from an art pencil on the pad. Still didn't work.I looked at the circuit diagram. The buttons are pulled to +5v with a resistor network and run into a 74HCT165 which converts the state of all the keys to serial. I found this button was 100 Ohms to ground whereas the others measure 55k to +5V as you would expect from the diagram. Then suspected the HCT165. I lifted the pin but found this was a few MOhms to gnd. It couldnt be the resistor network as that only linked the buttons to +5V. Lifted it anyway; definitely not that.The reading i get is exactly 100 Ohms. Really seems like a resistor value, but there are no 100 Ohm resistors on the board.I give up and cut the track from the pad then link it to the resistor network and HCT165. WorksSo, presumably there is a short in the PCB... seems very weird, but anyway it works now!The pics show my fix - red wires. Looks a bit of a mess but not as bad as what Fluke have already hacked on this meter - in green
Samsung Galaxy Tab Headphone Jack - Page 1
Forum section: electronics / repair

author: Cyberdragon
author_rank: Super Contributor
timestamp: June 12, 2017, 06:29:56 pm
content: It's pretty much brand new, but for some reason, the headphone jack decided to stop working. (crappy modern tech) I assume the solder joints just failed, but without a pry tool, I have no idea how to get it open. Any ideas?

author: PA0PBZ
author_rank: Super Contributor
timestamp: June 12, 2017, 06:49:22 pm
content: Take the glass out of the front bezel and you will be in

author: wraper
author_rank: Unknown
timestamp: June 12, 2017, 07:06:48 pm
content: Quote from: Cyberdragon on June 12, 2017, 06:29:56 pmIf solder joint really failed, it's a crappy user who abuses the jacks by putting force sideways. Like dropping with jack inside or putting into a bag with jack inside. In the past I've seen single phone arriving to warranty repair multiple times. First time connector soldered back, second time warranty reject as it's get broken off the PCB together with pads on the PCB. In any case most likely it's on a flex cable which is damaged by itself and can be replaced without soldering.If it has a warranty never try to fix phones/tablets yourself. First of all it's not that easy in many cases, as there may be tons of things attached by adhesive. But the most important is no access to genuine parts.

author: PA0PBZ
author_rank: Super Contributor
timestamp: June 12, 2017, 07:09:18 pm
content: Quote from: wraper on June 12, 2017, 07:06:48 pmTS didn't say what model it is, but the parts are normally easy available.

author: wraper
author_rank: Unknown
timestamp: June 13, 2017, 10:14:08 am
content: Quote from: PA0PBZ on June 12, 2017, 07:09:18 pmDid you miss the wordGENUINE? Of course there is a load of crap from China. If, for example, you buy samsung OLED display where are no 3rd party parts, most likely it will be recycled e-waste made to look as new. On top of that something might not fit, adhesives separate after a few days and similar. Probably not as bad with FPC cables, but still not genuine and a lot of crap parts available.
R&S CMU200 hangs after some time - Page 1
Forum section: electronics / repair

author: uski
author_rank: Frequent Contributor
timestamp: June 12, 2017, 08:49:56 pm
content: Hi,I have a R&S CMU200 test set. After a while it hangs (around half an hour of use). Looks like a thermal issue.Before opening the unit, I'd like to know if it's a common issue or if anybody had a similar problem, so I know what to look for.Beside this, the unit works perfectly fine.Thanks !

author: richnormand
author_rank: Unknown
timestamp: June 12, 2017, 09:13:18 pm
content: Could be quite a few things. Any messages ? Just random? Message on subsequent boot?1.Remove the main cover and see if it still does it.2.On mine the small fan on the corner of the display/computer module was seized. Removing the sticker and a adding few drops of oil has fixed it. Been going for a year now.Note the temperature warning tag on one of the chips. It should tell you if it has gone overtemp in the past.3.Also note the presence of a fan in the power supply module. The PSU shuts down if a certain temperature is exceeded. Look at the row of leds on the motherboard to see if a voltage goes missing.Lots of photos in my previous posting of the CMU200 PSU about a year ago.4.And, finally, there is the main fan on the CMU200 that was full of dust and also needed cleaning.I would do a quick look at these before hunting down an electronics, hard drive or software issue.Good luck with it.
Hp FN747AA Computer Monitor - Page 1
Forum section: electronics / repair

author: Fisher77
author_rank: Regular Contributor
timestamp: June 12, 2017, 01:38:49 pm
content: My main computer monitor died. The monitor did alot of jumping around(interference/jitter) is the best way to explain it, and then quit. When I turn it on now the backlight just faintly flashes on and off repeatedly. I tried it on a different PC with the same results. I removed all the covers and reconnected it to a computer and I can hear a pulsating buzzing noise coming from the power supply. The power on led flashes on and off along with the noise. All voltages on CN902 are good except there is no voltage on DIM. I checked what I know how to check. Was hoping I could some help diagnosing this, and learn something new along the way.http://i68.tinypic.com/o5w1ax.jpghttp://i66.tinypic.com/21actu0.jpghttp://i63.tinypic.com/mcrtpx.jpghttp://i68.tinypic.com/16jn5hl.jpghttp://i68.tinypic.com/1zyeeu.jpg
Desperately need a special Amphenol edge connector - Page 1
Forum section: electronics / repair

author: peteb2
author_rank: Regular Contributor
timestamp: June 12, 2017, 12:19:32 am
content: I have been handed a PCB from a power supply in the hope i can save it by replacing a cracked edge connector (and so a high-end piece of kit). I have traced the needed connector to multiple references on the Interweb but it appears to be always "NOT AVAILABLE" from just about every jelly-bean part supplier. (For some reason i get the feeling all production is committed and sold to manufacturers rather than the device being obsolete).......Is there a tiny chance anyone has a single Amphenol FCi # 10115788-007-LF that i can beg, steal or whatever. The Amphenol FCI Website mentions the connector can be obtained as a free sample but that involves me being a genuine design business with thousands of device ordering projections.Someone on here might have passed by this module with this connector on dumped recycled gear maybe... or someone may have or know of a source of spare-parts supply.Here's a few pictures of the thing: Any info really apreciated....

author: Armadillo
author_rank: Super Contributor
timestamp: June 12, 2017, 03:32:24 am
content: http://www.mouser.sg/ProductDetail/Amphenol-FCI/10115788-007LF/?qs=sGAEpiMZZMtWxQ3D3EXBNyRf3YnMYza0noWnPY%2f%252bPw0=

author: peteb2
author_rank: Regular Contributor
timestamp: June 12, 2017, 05:16:26 am
content: Thanks but my Mouser access is warning zero stock and zero on order...https://tinyurl.com/y8abadcv
Atten ADS1022C not work after firmware upgrade - Page 1
Forum section: electronics / repair

author: ManMan
author_rank: Newbie
timestamp: June 20, 2017, 02:15:01 pm
content: Hi AllPlease Help !my Atten ADS1022C+ not work after firmware upgrade ((I have only flash dump from ADS1102CAL (7" display)after flash this dump, i upgrade original Atten ADS1000 series firmware from USB, and get an almost working DSOdue to non-compliance hardware ((I need Atten ADS1022..ADS1042..ADS1062 or Siglent SDS1022C Flash dump.and Siglent SDS1022C latest FirmwareThe owner of this oscilloscope can not only help me, but also protect yourself by making a dump of your firmware.. All you need to download the firmware DUMP via JTAG is herehttps://cloud.mail.ru/public/D9hP/vaBkzVoyT
Dataman S4 - Page 1
Forum section: electronics / repair

author: grumpydoc
author_rank: Super Contributor
timestamp: June 08, 2017, 11:32:39 am
content: Does anyone have schematics for the Dataman S4?Mine seems to not want to program 32-pin chips, I suspect that the drive to pin 31 on the ZIF is up the creek.

author: grumpydoc
author_rank: Super Contributor
timestamp: June 08, 2017, 08:15:22 pm
content: Ah, turned out to be a PEBKAC issue, the fie user needed to read the fine manual!!Not that a circuit diagram for the S4 would not be useful.
Help identify phone jack for lenovo yoga - Page 1
Forum section: electronics / repair

author: Sp4
author_rank: Contributor
timestamp: June 08, 2017, 03:05:58 pm
content: HiI am having some hard times identifying the 3.5mm phone connector type for lenovo yoga laptop. The board code is "ls-b921p" and can be seen here:http://www.ebay.ca/itm/NEW-LENOVO-YOGA-3-11-USB-AUDIO-POWER-BUTTON-BOARD-LS-B921P-/112359585308?hash=I could buy the whole board, but it would be much nicer to get just the connector I blameDoes anyone know the product code for it?Thanks

author: difinity
author_rank: Newbie
timestamp: June 08, 2017, 03:39:52 pm
content: No idea of the product code but I think this is the part.https://www.aliexpress.com/item/Free-shipping-3-5mm-7pin-Laptop-Audio-Jack-headphone-jack-for-Dell-SONY-SAMSUNG-ect/32533327185.html

author: Sp4
author_rank: Contributor
timestamp: June 08, 2017, 04:23:10 pm
content: Thanks!I have missed this item somehow while digging there. Extra pair of eyes does help!Cheers,
Lecroy 9350 ch. 2 amplitude issues - Page 1
Forum section: electronics / repair

author: highroller
author_rank: Contributor
timestamp: June 07, 2017, 03:07:19 am
content: Hi,My Lecroy 9350 oscilloscope developped some noise spikes or amplitude jitter on channel 2.It happen on all input coupling type (DC, AC etc...) and at any volt/div setting but does not seem to affect the time.Not sure if it can be related to an input amplifier, a relay or part of the digital acquisition circuit.Any clues ?Thanks

author: highroller
author_rank: Contributor
timestamp: June 07, 2017, 03:24:03 am
content: More screen shot of the issue.

author: TAMHAN
author_rank: Frequent Contributor
timestamp: June 08, 2017, 02:35:06 am
content: Sorry to be stupid. One thing - did you already try moving the probes?I have one probe which, um, seems to be a little "smelly".

author: highroller
author_rank: Contributor
timestamp: June 08, 2017, 03:51:37 am
content: No probe attached, these pics are taken with the cal output connected with a 50ohm cable.The issue also appear without any connection to channel 2 input, I can see the noise spikes on an idle trace.

author: DaJMasta
author_rank: Super Contributor
timestamp: June 08, 2017, 05:37:09 am
content: Does the noise look sort of 'digital' in nature? In the second shot it almost looks like a bit of the ADC (that isn't the first bit) is just twitching a bit on its own, maybe there's a connection issue on the output of the data bus or on the receiver end.I think the chance it's that is sort of a longshot, but that sort of glitch does look somewhat distinctive and that could tell you something.

author: highroller
author_rank: Contributor
timestamp: June 08, 2017, 12:58:47 pm
content: Good point DajMasta.I start to think its digital in nature too, I may reflow some chips in the a/d part first.
Does anyone recognize this capacitor brand / series? - Page 1
Forum section: electronics / repair

author: cvanc
author_rank: Frequent Contributor
timestamp: June 04, 2017, 02:00:48 pm
content: Thanks...

author: David Hess
author_rank: Super Contributor
timestamp: June 04, 2017, 02:11:02 pm
content: My guess is that the PP means polypropylene film capacitor.

author: cuebus
author_rank: Unknown
timestamp: June 04, 2017, 08:39:10 pm
content: from what I can find on google, SEC = Southern Electronics Capacitor, PP51 being the series. Polypropylene & Foil in a radial box casing. 90-01 might be a date code.

author: cvanc
author_rank: Frequent Contributor
timestamp: June 06, 2017, 01:24:29 pm
content: Thank you both. The BOM says 'film' so yeah it's apparently a polypropylene. I Google-stalked but did not run across Southern Electric. Appreciate the info.I've got some old gear with a lot of these and one has failed as a dead short (literally a couple hundredths of an ohm measured in 4-wire mode). Weird failure mode for a film cap...

author: David Hess
author_rank: Super Contributor
timestamp: June 07, 2017, 12:48:51 am
content: Quote from: cvanc on June 06, 2017, 01:24:29 pmThat is not an odd failure more for a film/foil capacitor. Metalized film capacitors are the ones which self heal.
Looking for Lecroy 7200A Mantainance Manual - Page 1
Forum section: electronics / repair

author: JPortici
author_rank: Super Contributor
timestamp: June 12, 2017, 09:31:43 am
content: In a recent relapse of TEA i bought a faulty Lecroy 7200A mainframe + 2 x dual channel 500 MHz / 1GS/s plugins for 75 britbucksI found the mantainance manual for the plugins on elektrotanya but no luck yet on the 7200A, KO4BB has some resources but not the mantainance manual (at least i couldn't find it there)Does anybody have it? or some other place to check?

author: tru3533
author_rank: Regular Contributor
timestamp: June 12, 2017, 11:21:59 am
content: Check out this page:http://www.ccltd.com/LeCroy7200A/

author: JPortici
author_rank: Super Contributor
timestamp: June 12, 2017, 11:35:38 am
content: already checked out, it is mirrored at KO4BB!
Part identification: Worn down switch - Page 1
Forum section: electronics / repair

author: thf
author_rank: Newbie
timestamp: June 05, 2017, 08:07:16 pm
content: GreetingsThe hood in my kitchen is failing me, its the on/off switch that's worn down. I'm usually the parts procurer/finder at my job, but my searches come up blank.I hope someone knows the markings on the switch.Thanks in advance

author: Armadillo
author_rank: Super Contributor
timestamp: June 05, 2017, 08:27:46 pm
content: Pry Open it up from the plastic slot slowly and clean the contacts with deoxit.

author: Neomys Sapiens
author_rank: Super Contributor
timestamp: June 05, 2017, 11:56:04 pm
content: Manufacturer is either Schadow or Schurter

author: Gyro
author_rank: Super Contributor
timestamp: June 06, 2017, 09:38:32 am
content: Quote from: Armadillo on June 05, 2017, 08:27:46 pmIt's unlikely that a mains switch is suffering from contact oxidation, more likely is that the contacts or mechanism are worn out. A worn and arcing mains switch is a fire hazard.

author: thf
author_rank: Newbie
timestamp: June 06, 2017, 07:50:22 pm
content: Hi allThanks for the inputs! Didn't think to clean the contacts. However the wifu managed to kill it completely today, and that left a skid-marks on the PCB.. It was a bad solder on one of the pins! So a bit of solder managed to salvage the hood.What a crappy circuit design they made though.. All wires a connected on a single board with spade connections..Thanks again!
APC Smart UPS SUA 2200 - Page 1
Forum section: electronics / repair

author: Arun
author_rank: Newbie
timestamp: June 06, 2017, 11:51:52 am
content: Dear All,I have one SUA 2200 UPS. Unfortunately IC18 and IC19 (361-0015A) is burned. IC 18 number is missing on the component.Please check the attached photo. Can someone help me to get the IC 18 number ?Regards,Arun
Bad DC (27D) Speed Control Rheostat - Page 1
Forum section: electronics / repair

author: Matster Chief
author_rank: Contributor
timestamp: June 06, 2017, 03:32:36 pm
content: Hey all, I am working on repairing this Speed controler, had a few questions.Symptoms: When the speed controller is activated, it turns on fine. However, as you turn it up higher, it cuts out completely.This sounds like a bad potentiometer to me, but I'm no expert. Assuming I tested the potentiometer correctly, the pot went from around 84k down to about 24k about mid(ish) way through before returning to 84k. I can replace the whole control unit for about $150, but if it just a bad pot, I'd rather spend the $5-$10. Where is a good place to from here?
Repairing SL-1730SL20A Power supply. What is this component  - Page 1
Forum section: electronics / repair

author: JacquesBBB
author_rank: Frequent Contributor
timestamp: June 05, 2017, 09:00:29 pm
content: Dear All,I am trying to repair a linear 0-30V - 0-20A Power supply (SL-1730SL20A). The design is very similarto the more classical 0-30V - 0-3A,https://www.eevblog.com/forum/repair/tracking-problem-in-a-dual-bench-power-supply/msg529140/#msg529140but with a much larger transformer and a single canal.I suspect now that the problem comes from some shutdown feature, and came over this component whichI cannot identify. Quite surprisingly, it was connected only on one side, and the wire on the other side was cut.Is this a thermal sensor ? If yes, what should be its resistor ? Thanks !

author: JacquesBBB
author_rank: Frequent Contributor
timestamp: June 05, 2017, 09:05:27 pm
content: A view of the inside.The unknown device is circled in white. It was screwed on the heatsink of the power transitors.

author: anachrocomputer
author_rank: Regular Contributor
timestamp: June 05, 2017, 09:12:50 pm
content: Yes, it's a thermal cut-out. It opens the circuit at the marked temperature (75 deg C). If it's working properly, the two terminals should be a short circuit. When it gets too hot, the switch opens. The switch is rated for 220V, 1Amp.

author: JacquesBBB
author_rank: Frequent Contributor
timestamp: June 05, 2017, 09:18:23 pm
content: Thanks,Obviously, it is not working, as it is open at room temperature ( 20 °C).My problem is that I do not have the schematics and one of the wires of hte sensor was cut.I do not see very well where it should go.below is the main board. The sensor is connected on one side on 29 ( lower left) which goes then onthe + of V4 (top left).
220v soldering station converted to 110v - Page 1
Forum section: electronics / repair

author: natester
author_rank: Contributor
timestamp: June 08, 2017, 03:39:08 am
content: I just converted my 220v soldering station to 110v for use in the US. I think I have a general strategy that should work with most electronics.The details are here:https://nathan.vertile.com/blog/2017/06/04/converting-a-soldering-station-from-220v-to-110v/, but basically, I reduced the number of turns on the primary coil of the transformer, until an output marked 24v on the PCB, was close to 24v.What do y'all think?

author: P90
author_rank: Frequent Contributor
timestamp: June 08, 2017, 04:29:27 am
content: I've got a juicy step-up transformer for these situations...

author: Electro Detective
author_rank: Super Contributor
timestamp: June 08, 2017, 06:09:05 am
content: Diggin those wild redhead hair extensions

author: z01z
author_rank: Regular Contributor
timestamp: June 08, 2017, 06:58:48 am
content: This approach works for the voltage alone, but it might decrease the rated power, or will cause the transformer to overheat in the extreme.The original primary wire diameter was (hopefully) sized for a higher voltage/lower current combination. When you just simply halve the primary coil and keep the original wire size, you'll increase the current density in the primary.What will happen in your case depends on the original wire size, the transformer size and actual power needed. The chances are, the original wire was already undersized, but you might still get away with this. It all depends how the transformer rated power relates to the soldering iron power. Hopefully the full power is only needed for a short time when the iron is heated up to the working temperature then less power is enough to keep the temperature up.I'd keep an eye on the transformer temperature, to make sure it doesn't overheat.What is usually done for user selectable primary voltage is to have two identical primary windings and connect them in serial for 220V and in parallel for 110V.

author: stj
author_rank: Super Contributor
timestamp: June 08, 2017, 08:13:48 pm
content: the core was designed for 50Hz, just buy a new transformer.preferably with 120-0-120 or 120 + 120 split primary's
Tektronix 2465B Mexico - Page 1
Forum section: electronics / repair

author: Louis.cKontreras
author_rank: Newbie
timestamp: June 06, 2017, 05:47:07 am
content: Hi dear, this is my first question and first post.My name is Louis and I from Mexico. Living in Mexico.Sorry if I bothered anyone about it but I needed open other post. I don't found material about it.Ok, I have a 2465B oscilloscope and the problem is that my CTR (viewfinder) turns on but immediately goes out, it's a few seconds and I do not see any cursor, if someone is so kind to help me,Best regards friends.

author: joseph nicholas
author_rank: Frequent Contributor
timestamp: June 06, 2017, 11:16:04 am
content: Get a schematic for the scope and check all voltages. I assume you have a multimeter.

author: Louis.cKontreras
author_rank: Newbie
timestamp: June 06, 2017, 10:30:03 pm
content: Yes, I have a multimeter and I have the service manual, but I wanted extra help in reference to the experiences. Thanks for your help.
Free samsung tv lines on left side of screen - Page 1
Forum section: electronics / repair

author: kapicarules
author_rank: Newbie
timestamp: May 31, 2017, 03:08:03 am
content: i got a free samsung LN46B650T1F 46 inch tv from the side of the road. it works perfectly except that It has these lines on the left side. I googled it and some said tcon board (i suspect that) or the video input board (All inputs work and this issue happens on all inputs so its not that). i want to get it working so i can use it or even sell it for a bit of cash (after an extremely thorough test)

author: mzacharias
author_rank: Frequent Contributor
timestamp: May 31, 2017, 08:15:25 pm
content: I think I would also check for evidence of corrosion along the top edge of the panel corresponding with the artifact in the picture. Liquid into the tab bond might cause something like this.

author: kapicarules
author_rank: Newbie
timestamp: May 31, 2017, 08:28:44 pm
content: no corrosion, its clean.

author: BMack
author_rank: Regular Contributor
timestamp: June 01, 2017, 05:35:26 am
content: I lean towards T-con because of that pattern across the entire picture. I think you lucked out.

author: kapicarules
author_rank: Newbie
timestamp: June 01, 2017, 05:27:18 pm
content: its coming in a couple weeks so we will find out

author: Anks
author_rank: Frequent Contributor
timestamp: June 01, 2017, 06:50:58 pm
content: Samsungs genrally have a jumper that allows you to test the panel

author: kapicarules
author_rank: Newbie
timestamp: June 01, 2017, 08:08:45 pm
content: and where do i find that jumper?

author: BMack
author_rank: Regular Contributor
timestamp: June 03, 2017, 06:56:53 am
content: Quote from: kapicarules on June 01, 2017, 08:08:45 pmOn the T-con(holes 3 and 4) but it's meant to give you a test pattern and take the main board out of the equation.
Fluke 187 battery cover screws.  Where to buy? - Page 1
Forum section: electronics / repair

author: jesuscf
author_rank: Frequent Contributor
timestamp: May 31, 2017, 10:55:19 pm
content: Does anybody knows where to buy the battery cover screws for the Fluke 187? The ones indicated in the attached picture...

author: ModemHead
author_rank: Frequent Contributor
timestamp: June 01, 2017, 09:43:58 pm
content: Try searching for "fluke 948609". It looks like Newark/element14 has them, and at least one seller on eBay.

author: jesuscf
author_rank: Frequent Contributor
timestamp: June 02, 2017, 03:26:12 pm
content: Quote from: ModemHead on June 01, 2017, 09:43:58 pmThose are the ones! Thank you very much! I'll order from Newark.
New Jersey Becomes the 12th State to Consider Right to Repair Legislation  - Page 1
Forum section: electronics / repair

author: lordvader88
author_rank: Frequent Contributor
timestamp: June 05, 2017, 04:44:08 am
content: http://www.tathasta.com/2017/06/new-jersey-becomes-12th-state-to.htmlQuoteGood, and don't forget about learning some EE history, in case we all end up back in the dark ages and have to start with vacuum tubes again and making our own resistors and capacitors too

author: james_s
author_rank: Super Contributor
timestamp: June 05, 2017, 07:04:27 am
content: I'd like to see something of this nature at a federal level so it affects the whole country. Make schematics available, sell replacements for all custom/programmable parts or offer the firmware binary to program blank parts. If a product is deemed obsolete and support is dropped, release all the firmware binaries.

author: GK
author_rank: Super Contributor
timestamp: June 05, 2017, 08:59:28 am
content: I've been wondering if legislation along these lines is inevitable/will eventually be common place, not necessarily from a consumer rights perspective, but from an environmental one. The electronics industry has already been target by RoHS to limit hazardous substances going to landfill, so it would seem a natural progression to legislate in some form or another against excessive production of electronics goods destined to landfill by targeting what is effectively, in many respects, planned obsolescence.
Tektronix TDS754D color CRT adjustments - Page 1
Forum section: electronics / repair

author: eKretz
author_rank: Frequent Contributor
timestamp: June 04, 2017, 08:19:53 pm
content: I recently picked up a TDS754D from a fellow member here and it had a very dim CRT. I've adjusted the brightness and contrast per the SM but this has revealed or created a focus issue. The display is sharp in the center but soft around the edges. Has anyone got any experience dialing in the focus on one of these?

author: NavyBOFH
author_rank: Contributor
timestamp: June 05, 2017, 01:28:56 am
content: If that's the case you want to go back and check the cathode/anode/grid voltages if you have the right equipment (or if there are test points available). Whenever I've had to repair anything with a CRT I've noticed those issues like you're describing coming down to a bad power supply or driver. The CRT itself could be showing its age as well...

author: eKretz
author_rank: Frequent Contributor
timestamp: June 05, 2017, 07:24:07 am
content: Found some info from TekScopes Yahoo group that ID'ed some of the pots controlling focus so I set up my two 754's next to each other so I could drive the troublesome CRT with the other scope - as a troubleshooting measure and so I could make adjustments without having to remove the CRT from the chassis.The 754A has a very sharp display with no issues, the 754D has the soft around the edges issue. When I drove the D's CRT with the A's board, it still had the same soft focus around the edges, so it seemed very unlikely to me that it was related to power supply issues.At this point I set up the composite display pattern and started tweaking focus pots. After about a half an hour worth of dialing center, horizontal and vertical focus pots I got it about as good as it's going to get. It is much improved but still just a tad soft at two of the extreme opposite corners. It's pretty much invisible unless you're looking for it, so I'm happy with where it's at now.Thanks go to TekScopes and Andy who I PM'ed for some info regarding the pots and ID'ing which does what.
For.A FA-130P time base corector repair. - Page 1
Forum section: electronics / repair

author: Jare
author_rank: Newbie
timestamp: May 31, 2017, 08:09:26 pm
content: Hi.I have a For.A FA-130P time base corector that is broken.It works when you turn it on when it's cold,but after ten minutes it's got a little hot, and the image starts shaking up and down.I figured out a bit by blowing on various ic's with air when it was hot,and if i cool down an ic as it says "Sony 6090 CXA1054" on,the picture will be fine again.Could it be that the ic is broken?And where can i find a new one i google it but found no one who sold the "Sony 6090 CXA1054".Is there any other model that could work instead and what is it for?Thanks.

author: coromonadalix
author_rank: Super Contributor
timestamp: May 31, 2017, 08:22:49 pm
content: Search for Sony CXA1054 ... unable to find a pdf sheet, many websites pretends but give nothing.Check for bad solders, bad contacts near that chip, on the chip, or nearby capacitors

author: coromonadalix
author_rank: Super Contributor
timestamp: May 31, 2017, 08:29:09 pm
content: On aliexpress they say it's a regulatorhttps://www.aliexpress.com/item/CXA1054-new-SMT-chip/32575178551.html
Fluke 8842a Repair / help - Page 1
Forum section: electronics / repair

author: joerice01
author_rank: Newbie
timestamp: May 30, 2017, 07:00:29 am
content: Hi all,I recently purchased a fluke 8842a DMM for my bench.After opening it up I saw that it looks like the copper is lifting off the optional boards.I guess this is just due to It's age...after testing all the inputs I discovered that the low VDC range seems to float after test.If I test 5v the display reads 5v, then if I remove the probes the reading will stay at 5v and trickle down a little bit.If I then short the probes the reading will return to 0.0vthis doesn't happen on the higher DC ranges, I can hear a relay switch over which leads me to believe there is a fault in the lower range circuit.Luckily for me the 8842a manual has an extensive troubleshooting section, so will take some time this weekend to go through it and test.Has anyone had an experience with this type of problem before?Thanks for your help.

author: 2N3055
author_rank: Super Contributor
timestamp: May 30, 2017, 07:29:52 am
content: That is not copper lifting.. That is solder.. It doesn't have galvanic tin protection, but copper was covered with solder.. It was quite common in that era..In the lower DC ranges, meter has input impedance on order of many Giga Ohms. In order to check zero offset you need to short inputs...So those two are not problems...Regards,Sinisa

author: joerice01
author_rank: Newbie
timestamp: May 30, 2017, 10:52:23 am
content: Sinisa,Thanks for sharing your knowledge with me.I don't have a lot of experience with gear from this era...Thanks again.

author: mzacharias
author_rank: Frequent Contributor
timestamp: May 30, 2017, 01:16:19 pm
content: Quote from: joerice01 on May 30, 2017, 07:00:29 amThis is quite normal due to the extremely high (several Gig-Ohms) input impedance at the 20V range and below. Above that, at the 200V range for example, the input impedance is 10 meg and so even this internal resistive load will drain off the voltage reading once the probes are removed from the voltage source.This question comes up fairly often.
Cleaning high voltage PCB with vaporised tracks - Page 1
Forum section: electronics / repair

author: fourtytwo42
author_rank: Super Contributor
timestamp: May 30, 2017, 11:36:42 am
content: Just had a hard start event caused by my stupid diagnostic code in SMPS that has vaporized the tracks around the TO220 half bridge mosfets leaving copper residue all over the immediate area. The HB operates on a 200Vdc input so kinda the limit already for clearance on TO220 pads so I wonder if anybody has any methods for removing the copper residue to restore the insulation performance before repairing the blown tracks with wire ?I hope you can see the problem in the attached picture, thanks in advance

author: DenzilPenberthy
author_rank: Frequent Contributor
timestamp: May 30, 2017, 12:03:20 pm
content: My approach to this is usually a good scrub with flux cleaner to get off as much of the loose carbon etc as possible then careful use of a scalpel to scrape the burnt surface away from between the traces. If the PCB is badly burnt this can extend to cutting quite a deep groove in to the PCB material.

author: DenzilPenberthy
author_rank: Frequent Contributor
timestamp: May 30, 2017, 12:10:57 pm
content: ... if you wanted to be really keen you could test the insulation resistance between the traces after you've cleaned and scraped between them with a Megger (or similar).Remove the affected component from the pads, cut the traces nearby so that you're not going to back-feed into the rest of the circuit or damage anything with the test voltage. Then after you've cleaned up the burnt area, give it a good test with the Megger to make sure it has adequate high-voltage insulation. Then repair your cut tracks by scraping back the solder resist either side of the break and bridge with a bit of wire and solder. Maybe re-cover the scraped away bits of PCB and traces with conformal coating afterwards as well...

author: fourtytwo42
author_rank: Super Contributor
timestamp: May 30, 2017, 12:29:01 pm
content: Thank you Denzil, I like the word scrub, fresh toothbrush comes to mind. I use isopropyl alcohol for most jobs, I will try that first and then maybe something more abrasive (toothpaste) followed by more IPA then a very close inspection under a magnifier. Fortunately there doesn't seem to be any burning of the substrate, the bang was so loud foil d*** come to mind! Good idea the scalpal scraping tooI already use conformal coating as this will live outside when its done testing

author: Richard Head
author_rank: Frequent Contributor
timestamp: May 30, 2017, 12:45:38 pm
content: A good way to remove the copper after a blow up is to roll a molten ball of solder over the area where the metallization has occurred. The solder picks up the metal and leaves behind only flux. Just apply a liberal amount of solder to the iron tip and play it over the are where the metallization is. It works wonders. Once you've removed all the burned flux there isn't a trace of metallization left.

author: fourtytwo42
author_rank: Super Contributor
timestamp: May 30, 2017, 01:01:42 pm
content: Woww Richard that is a really good idea, I will try that first, many thanks
capacitance and ESR for this capacitor? - Page 1
Forum section: electronics / repair

author: kgavionics
author_rank: Regular Contributor
timestamp: May 31, 2017, 01:47:17 am
content: HiSomeone gave me away a 50inch plasma tv that doesn't turn on.i took it apart and i right away i noticed that there's two bulged caps 3300uF 100V.To be sure that the problem is coming from these caps i desoldered them and measured the capacitance and the ESR.C was around 2750 uF for both ( which i found quite low even with 10% tolerance)ESR was 0.13 ohm.According to Esr table found on internet ESR should not exeed 0.1ohm for this type of capacitor.My question: are these caps good or not?thanks in advance

author: ahbushnell
author_rank: Frequent Contributor
timestamp: May 31, 2017, 02:57:08 am
content: If they are venting gas they are dead.How did you measure the ESR?Andy

author: kgavionics
author_rank: Regular Contributor
timestamp: May 31, 2017, 03:09:02 am
content: Quote from: ahbushnell on May 31, 2017, 02:57:08 amthanx AndyThe only way to figure out if the capacitor is good is capacitance and ESR.i measured ESR using a cheap Chinese component tester bought from ebay.

author: ahbushnell
author_rank: Frequent Contributor
timestamp: May 31, 2017, 03:30:47 am
content: I think it's bad.Hook it up to a DC power supply and charge the capacitor. Does it draw current? Make sure the polarity is correct.Andy

author: bsalai
author_rank: Regular Contributor
timestamp: May 31, 2017, 10:53:43 am
content: I'd order some new ones. Bulging caps are so often the problem that it's worth a couple of dollars to replace them. I've fixed a few things this way.Sent from my iPhone using Tapatalk

author: cnqhdszq
author_rank: Regular Contributor
timestamp: June 01, 2017, 03:41:13 pm
content: you had better to test The capacitor with a LCR Bridge .

author: cnqhdszq
author_rank: Regular Contributor
timestamp: June 01, 2017, 03:49:12 pm
content: If It had gas leakage out before ,It must be bad now ,do not trust the result of chinese tester.It just a toy
Identifying SMD component - 'TXPA' - Page 1
Forum section: electronics / repair

author: Franc
author_rank: Regular Contributor
timestamp: May 29, 2017, 11:27:01 pm
content: Hi All!!I need to change this damaged smd component. SOT-553 package.The only identification is 'TXPA', but none info in google.Thanks for help!

author: ataradov
author_rank: Super Contributor
timestamp: May 30, 2017, 01:13:14 am
content: LM26CIM5-XPAIt is SOT23-5.

author: Franc
author_rank: Regular Contributor
timestamp: May 30, 2017, 12:04:02 pm
content: Thanks Alex!!I found in Mouser...have a nice day!
Possible fault in motherboard for no signal to monitor. - Page 1
Forum section: electronics / repair

author: lepden
author_rank: Contributor
timestamp: June 02, 2017, 02:30:35 am
content: Ok. This is not about a single computer, I've come across a number of cases with the same syndrome and so far ended up replacing the motherboard. Usually this is fixed with re-seating the ram stick, but after trying all possible troubleshooting if it's not fixed then it's either the processor or motherboard. My question is, can a failed CPU result in "no signal" on the monitor? If it's the motherboard fault which components should I be looking for a fault?
install new HD in lecroy waverunner 62xi - Page 1
Forum section: electronics / repair

author: al3x
author_rank: Newbie
timestamp: May 28, 2017, 09:58:56 pm
content: i see adquiring new oscilloscope, one touch and great Sampling rate, in my locality sell this oscilloscope but i have dudes because the person not give me the hdd.can i install new OS (for example win7 or other win) in new HDD and install x-stream?Should I be freeze the HDD?where find the software for new hdd??i need any licence for install x-stream?this for lecroy waverunner 62xithanks

author: abraxa
author_rank: Frequent Contributor
timestamp: May 29, 2017, 05:31:08 am
content: The HDD contains the calibration data, so if you don't have the original HDD then you also don't have the calibration data.

author: amc184
author_rank: Regular Contributor
timestamp: June 03, 2017, 05:58:27 am
content: I have seen discussion about replacing missing or failed HDDs on LeCroy scopes of this era before. The conclusion seemed to be that there are no recovery discs for them online, and LeCroy either couldn't or wouldn't provide them. I have a similar LeCroy scope, and the first thing I did when I got it was clone the HDD.Unless they'll include the HDD, or you find that you can definitely get some kind of install disc, Iwould notbuy that scope.
Yamaha RX-V659 Power problem - Page 1
Forum section: electronics / repair

author: ysonmezer
author_rank: Newbie
timestamp: May 27, 2017, 08:04:05 pm
content: I use a Yamaha RX-V659 receiver. I had previously burned the capacitor on the power board 22nf 630v. I changed it with 22nf 1000v so that it would burn again. The device recently made a power failure. This condenser series had a 220k resistor burned. I changed but the device did not work. These two components are attached to the series burnt surface mount 10v zener. I changed and worked.

author: mzacharias
author_rank: Frequent Contributor
timestamp: May 29, 2017, 11:58:43 am
content: R661 should be 2.2K (2200 ohms) not 220K.

author: oldway
author_rank: Super Contributor
timestamp: May 29, 2017, 04:22:39 pm
content: And C654 must be a X2 capacitor for safety.With C654 = 22nf 275VacX2, you should never burn R661, nor the zener diode.
Tektronix 2247A no trace question - Page 1
Forum section: electronics / repair

author: rdl
author_rank: Super Contributor
timestamp: May 26, 2017, 06:43:57 pm
content: I have a Tektronix 2247A that I got over 10 years ago. Though I don't use it that much since getting a DS1052E, and when I do it's usually just one channel, but yesterday I actually tried to use channel 2 and found that there's no trace. I'm sure it worked at one time. What I'd like to know is whether this might be an easy fix or not. So if anybody wants to take a guess, I'd appreciate it. Even with just one channel it's still very useful and I'm not sure it's even a good idea to go poking around inside and risk making things worse.edit: channel 2 not channel B

author: David Hess
author_rank: Super Contributor
timestamp: May 27, 2017, 01:02:26 am
content: Channel B? What channel B?Channels are designated with the numbers from 1 to 4 and sweeps and triggers are designated with the letters A, B, and C.

author: rdl
author_rank: Super Contributor
timestamp: May 27, 2017, 02:00:06 am
content: Sorry, I meant 2. All channels have a trace except channel 2.

author: David Hess
author_rank: Super Contributor
timestamp: May 27, 2017, 02:45:49 am
content: There are some non-intrusive measurements that you could make which would determine the failure or at least narrow down the possibilities. Many of them are repairable but will require unsoldering parts and replacing them. You will need the service manual which has schematics.The oscilloscope also has some self diagnostic routines which might point to the problem.Likely failures which could cause what you describe are:1. Failure of the input amplifier. This would be difficult to fix and require a custom Tektronix hybrid.2. Failure of the JFET or CMOS analog circuits which control the trace position. This would be easy to fix.3. Failure of the digital I/O circuits which control trace 2. This would be easy to fix.

author: rdl
author_rank: Super Contributor
timestamp: May 27, 2017, 03:09:36 am
content: I was able to track down a copy of the service manual. I couldn't find an operation manual, but I found one for the 2246 which seems close enough and will be a big help. When I first got the 2247A, I just followed general scope usage guides to figure out the basic usage and never bothered with the more advanced features (though I did figure out some parts).For now, I don't think I'll take any chances. I finally have all my electronic stuff in one area instead of two different rooms, so If I need more than one channel I can turn on the Rigol. The rest of the time I'll be able to use the 2247A.