hybridfree/eevblog-posts huggingface dataset:
Some sort of supressor/spark gap? - Page 1
Forum section: electronics / repair

author: Chris56000
author_rank: Frequent Contributor
timestamp: April 02, 2019, 11:24:05 am
content: Hi!Does anyone recognise this?It's a surface-mount component consisting of two metal electrodes soldered to the PCB power input lands, normally an open-circuit, with about three thin layers of brown insulating material between the electrodes, and has a logo consisting of an capital 'X' where the halves overlap slightly then "A03F" and "BSGZ" underneath on the second line?Sorry for the poor quality of the photos!Chris Williams

author: pbarton
author_rank: Frequent Contributor
timestamp: April 02, 2019, 12:26:45 pm
content: PolySwitch Resettable DevicesLittelfuse 0.3A Surface Mount Resettable Fuse, 60V dchttps://in.rsdelivers.com/product/littelfuse/rf0323-000/littelfuse-03a-resettable-surface-mount-fuse-60v/1740463

author: Chris56000
author_rank: Frequent Contributor
timestamp: April 02, 2019, 02:20:03 pm
content: Hi!Member PBarton - thank you very much for your time - that's why myself and my friend couldn't seem to find it - we both thought it was some sort of spark-gap or suppressor across the lines rather than a fuse in series with them!Kind regards,Chris Williams

author: Chris56000
author_rank: Frequent Contributor
timestamp: April 27, 2019, 09:23:02 am
content: HiJust a quickie update to say my friend has successfully repaired the unit that the Littlefuse 60V polyswitch shown in my photo came from – the new replacement suggested by Member PBarton was an exact match, and the fault was traced to another 27–36V T.V.S. suppressor diode across the power input s/c, and the unit, some sort of industrial network router, now been shipped out serviced & tested!Member PBarton, thank you once again for your help Sir!Chris Williams
DIP8 precision resistor networks? - Page 1
Forum section: electronics / repair

author: essele
author_rank: Frequent Contributor
timestamp: April 24, 2019, 11:12:46 am
content: I've just found a faulty resistor network on a device I'm repairing and don't seem to be able to find any sensible source for these.The old part is a BECKMAN 694-3-R10kD, which is a 4x10K 0.5% resistor network in a DIP8 package, with a 0.05% ratio tolerance and a 5ppm TCR tracking tolerance.These seem to have been obsoleted back in 2013.I can't actually find much in the way of DIP8 resistor networks in any of the UK suppliers (I've checked Farnell, RS, Mouser and Digikey)My best option at the moment seems to be to use a surface mount part and mount it on an adapter ... that just seems a bit horrible. Any better approaches here?Thanks.

author: pbarton
author_rank: Frequent Contributor
timestamp: April 24, 2019, 03:32:02 pm
content: https://www.ebay.co.uk/itm/232732950294do check the postage cost!!https://www.ebay.co.uk/itm/332597943508EDIT:https://www.ebay.com/itm/272418690682

author: Vgkid
author_rank: Super Contributor
timestamp: April 24, 2019, 03:36:38 pm
content: Vishay tdp , rkmpTt electronics 1987/1989/1998/1999

author: essele
author_rank: Frequent Contributor
timestamp: April 24, 2019, 03:56:22 pm
content: Thanks for the responses...@Vgkid ... they are all 14pin by the looks of it.@pbarton ... they look ok, just checking on the postage cost.

author: LateLesley
author_rank: Frequent Contributor
timestamp: April 24, 2019, 05:01:37 pm
content: I found this on mouser.https://eu.mouser.com/ProductDetail/Bourns/4108R-1-103LF?qs=sGAEpiMZZMvrmc6UYKmaNdoL6XYdgUsUcpDkGNC7%2FCg%3DEven though the pic is a larger package, it says it's DIP-8 in the description. So it'll be using a "stock image"

author: essele
author_rank: Frequent Contributor
timestamp: April 24, 2019, 05:42:09 pm
content: Hi LateLesley,Good find, not sure how I missed these, however they are 2% and with generally lower specs. I think I'm still erring of the side of SMT and an adapter.

author: essele
author_rank: Frequent Contributor
timestamp: April 24, 2019, 06:15:50 pm
content: I suppose another option would be to use four of these:PTF5610K000BZEB (https://www.mouser.co.uk/ProductDetail/Vishay-Dale/PTF5610K000BZEB?qs=sGAEpiMZZMsPqMdJzcrNwnPpI93fAKplbiQqSM8wfN4%3D)The absolute TCR is the same as the matching TCR on the BECKMAN part, however I suppose they could heat differently and still blow the original specs.

author: Kleinstein
author_rank: Super Contributor
timestamp: April 24, 2019, 06:25:44 pm
content: One could try 4 individual resistors like PTF56.In SO8 form factor Farnell has AORN and maybe HTRN series resistor, these might be good enough, though not sure.What performance is actually needed ? One might get away with more tolerance or higher TC.
Speaker repair glue recommendations - Page 1
Forum section: electronics / repair

author: tim.savage
author_rank: Unknown
timestamp: April 23, 2019, 11:15:41 pm
content: Was given a pair of Warfedale E70 speakers. There were in good condition just dirty/dusty and the speaker grills needed replacing.After testing the 10" driver in one of them is quite distorted (especially at low volumes), gently pushing on the cone I can feel it grating. I've removed the problematic speaker and the alignment cone (?) has come away from the basket (see pics). Holding it in place and again gently pushing on the cone and the grating is gone.Does anybody have recommendations for glue to repair? Would be metal to paper.Cheers

author: RandallMcRee
author_rank: Frequent Contributor
timestamp: April 23, 2019, 11:43:30 pm
content: Its a spider, so:https://www.google.com/search?q=speaker+spider+glue&rlz=1C1CHBF_enUS742US742&oq=speaker+spider+glue&aqs=chrome..69i57.3463j1j8&sourceid=chrome&ie=UTF-8show epoxy as a common choice, which is what I would have guessed. Although many so-called speaker epoxies show up in the google results probably the most "special" thing about them is a longer working time. You don't want 5-minute epoxy. It cures too fast--you need to make sure that the spider is accurately positioned.Also, you probably need to clean the metal surface--be really careful not to introduce any metallic particles into the voice cone/magnet area--you will not be able to get them out without complete dissasembly.Hopefully, you can find a good youtube video on it.

author: tim.savage
author_rank: Unknown
timestamp: April 24, 2019, 12:00:29 am
content: Knew there had to be a term for that part!I'll probably just go with 30min epoxy.Cheers

author: tim.savage
author_rank: Unknown
timestamp: April 24, 2019, 07:43:45 am
content: High strength (slow cure) Epoxy has done the trick.Still got 8 hours to go before I can run it again, but pushing on the cone is now smooth all the scratching is gone.
High Voltage power Supply Oltronix A2,5K-10R - Page 1
Forum section: electronics / repair

author: xantia_99
author_rank: Contributor
timestamp: April 23, 2019, 01:26:56 pm
content: HiI got an Oltronix A2,5K-10R in front of me. It should be possible to get +- 2.5 KVolt from power supply, but just now nothing. The meter indicate +-2.5 KVolt voltage but nothing at the outlet on the back. The tubes indicate some work.The problem is I got no schematics or service manual. In my opinion the design is a mess. However I need to get it to work again.Best RegardsStephan
Inverter repair TO-92 package identification please - Page 1
Forum section: electronics / repair

author: pcmad
author_rank: Regular Contributor
timestamp: July 21, 2020, 12:37:55 am
content: I am in process of repairing 12v inverter it worked and then blue smoke came out (might of put 14v on it) . Can anyone identify the damaged TO-92 package?thinking could be bjt or mosfetmore images herehttp://pcmad.modulewebdevelopment.com/inverter/what i can seepsa05611any ideas please answer with a % of centanlyalso could i replace with a similar component or would it have to do that exact modelthank you

author: TheMG
author_rank: Frequent Contributor
timestamp: July 21, 2020, 12:48:16 am
content: MPSA05https://www.onsemi.com/pub/Collateral/MPSA05-D.PDFJust a run-of-the-mill NPN transistor really.

author: james_s
author_rank: Super Contributor
timestamp: July 21, 2020, 01:16:15 am
content: Yes, pretty sure that's it.A 12V inverter ought to tolerate 14V without any trouble though, automotive/RV/marine systems can easily reach that level with the engine running. Could you have connected it backwards?
BWD cro - Page 1
Forum section: electronics / repair

author: Lucipla
author_rank: Newbie
timestamp: April 23, 2019, 03:40:19 am
content: Hi allThanks youI am restoring a old BWD 835 cro and it keep blowing the 10 nano cap in the main supply before the rectifying diodes , anyone have any idea about this problem ?Kind regardsLucipla

author: tautech
author_rank: Super Contributor
timestamp: April 23, 2019, 09:45:42 am
content: Welcome to the forum.C604 should be a mains rated Y class cap.As it's across the L and N it needs be 275VAC rated at least.Google 'x and y rated caps' for further info.However it's just for mains suppression and it's not necessary for operation. Value is not critical and you can get Y class caps from Jaycar when you're next there.In the meanwhile just use the scope.
Weird HDMI signal loss issue? Videos inside! - Page 1
Forum section: electronics / repair

author: AmmoJammo
author_rank: Frequent Contributor
timestamp: April 22, 2019, 11:06:45 am
content: Basically, cables joined together, works fine.2 cables, going via a single switcher, doesn't work.3 cables, going via 2 switchers, works fine...https://youtu.be/6Jduql5ez3ghttps://youtu.be/5M1_jLih5Ig

author: Psi
author_rank: Super Contributor
timestamp: April 22, 2019, 11:19:32 am
content: There are a lot of crappy HDMI spliter boxes coming out of china that don't conform to the spec for speed/integritySo my guess is that one of your spliter boxes is at fault.Also,your spliter boxes appear to have no external power. Are they passive switches or do they use some sort of power over HDMI?Maybe they are using to much power and causing brownout,If they uses mechanically switches the unshielded'ness of that maybe the problem.

author: AmmoJammo
author_rank: Frequent Contributor
timestamp: April 22, 2019, 11:21:52 am
content: Quote from: Psi on April 22, 2019, 11:19:32 amThe switcher actually works fine with the same DVD player, same cables, connected to a different tv

author: AmmoJammo
author_rank: Frequent Contributor
timestamp: April 22, 2019, 11:57:33 am
content: Quote from: Psi on April 22, 2019, 11:19:32 amThey are powered from the device.However, the larger, 5 input unit, that displays the issues, can also accept external power.Powering it externally makes no difference.

author: scribble
author_rank: Contributor
timestamp: April 23, 2019, 09:04:05 am
content: Googling Digitech 5x1 switcher (since you didn't mention model numbers) for me brings up Jaycar Australia link and that says it's been discontinued and replaced with a new model, so maybe it's just a junky / badly designed switcher? Coloured snow is indicative of a handshaking issues, have you tried the DVD player different inputs (since it seemed to be the one complaining)? What about other hdmi sources like a computer or console?

author: AmmoJammo
author_rank: Frequent Contributor
timestamp: April 23, 2019, 09:33:54 am
content: Quote from: scribble on April 23, 2019, 09:04:05 amJaycar generally discontinue things when they find a cheaper option, they can sell for the same priceThe DVD player has the same effect on all inputs, it works fine connected directly to the TV. Other devices will result in similar issues through this switcher.I'm using the switcher to connect a mini PC, Blu Ray player, DVD player, and Raspberry Pi.I believe I have found the fix, but I'm still wondering if anyone can diagnose the issue.
Hello needed Tektronix 2467B - Page 1
Forum section: electronics / repair

author: vjo
author_rank: Newbie
timestamp: April 23, 2019, 08:02:33 am
content: dear members, I am from india ( just getting started into electronics as a hobbyist ) and my friend (who stays at sf bay region california) has got me a Tektronix 2467b oscilloscope (he had got a good deal in ebay don't know the seller), any member in sfbay region who is willing to help him inspect, check for nvram replacement and any other component replacement in any of the boards.. because once it comes to india it will be difficult to try and fix. kindly help.
Yaesu FT-60 LCD - Page 1
Forum section: electronics / repair

author: @rt
author_rank: Super Contributor
timestamp: April 23, 2019, 07:21:09 am
content: HiI got one of these handheld POS radios from eBay. I’ll probably just send it back rather than tinker with it,but it has bad LCD contrast the has no adjustable setting in the menu.Viewing it straight on, it’s right at the edge of being invisible, and it sharp when viewed from the top.I thought there might be a PCB pot or something, but looks like it’s just a bare LCD.My question is how do they set LCD contrast in the first place?
Kenwood TS-700A - Page 1
Forum section: electronics / repair

author: bob91343
author_rank: Super Contributor
timestamp: April 22, 2019, 10:27:25 pm
content: I have one of these to repair. The problem appears to be in the power supply. Has anyone worked on one of these?This unit runs either from 120V line or 13.8 VDC with automatic switching. Some of the radio runs from a 21 Volt supply which is generated by, I think, an oscillator and voltage doubler. So far I have discovered a diode that never got soldered properly and corrected it, but still no operation.The 21V supply runs at about 13V. There is a fuse in its output and when I remove the fuse the 13V is unchanged. There is also a 9V supply that is okay, and adjusts fine, but the 21V is insensitive to adjustment.Looking at what I think is the output of the oscillator, it seems not to be oscillating. I will continue to test parts and inspect soldering but wonder if anyone has worked on one of these old radios.

author: CoopedUp
author_rank: Regular Contributor
timestamp: April 22, 2019, 10:30:52 pm
content: I'm no expert but I have worked on many tube radios and I know that if it's old it needs new electrolytic capacitors... that could definitely mess the power supply up. unless you knew that and have already done that...

author: bob91343
author_rank: Super Contributor
timestamp: April 22, 2019, 11:01:17 pm
content: I do know that, but for the most part won't replace a capacitor that tests good. If it doesn't look good, I may replace, but if it still has its marked capacitance, low leakage and ESR, I leave well enough alone.It's not working, and I can't blame any of the capacitors I have tested so far. There are others, and therein may lie the cause of the problem, but it's dicey to climb in there and measure.At the point where I think I should see an oscillation wave, I see clean dc. Well, a few millovolts power line ripple is all. The oscillator looks at first like a phase shift oscillator but there is an inductor as well. Before I get heavy handed with this unit I want to understand how it's supposed to work.I also have worked on many a tube unit and am comfortable with their issues. This radio does appear to be unique in the power supply at least. I may pull the fuse and see if it works with 21V from an external supply. If so, that tells me it's a power problem. If not, it tells me almost nothing.
Re: Oscilloscope repairing tutorials - Page 1
Forum section: electronics / repair

author: Dhanushka
author_rank: Regular Contributor
timestamp: April 24, 2019, 03:45:57 pm
content: Can you mention few good tutorials (both video and web) about oscilloscope repairing tutorials for beginners on the internet?

author: Old Printer
author_rank: Frequent Contributor
timestamp: April 24, 2019, 06:20:14 pm
content: There are a number of scope repair threads here, the search function will help you find them. I would not call them tutorials, as for they just cover what was wrong with the scope. YouTube has some as well, check Daves channel EEVBlog, and Alan Wolke w2aew has one on calibrating an older analog scope.

author: tggzzz
author_rank: Super Contributor
timestamp: April 24, 2019, 06:38:35 pm
content: You don't give any clue as to your experience and capabilities, so it is difficult to make recommendations.However:there areverysignificant differences between "old" and "new" scopesbeginners should not be inside scopes; there are "entertainingly" dangerous voltages associated with CRTs and SMPSs
RDIMM bypass module - Page 1
Forum section: electronics / repair

author: coquinho
author_rank: Contributor
timestamp: April 21, 2019, 03:24:08 pm
content: I'm wondering if there is a way to bypass the register IC on the RDIMM DDR3 stick, effectively making it a UDIMM, just by removing the IC and connecting the corresponding pads? IC SSTE32882https://www.idt.com/document/dst/idt-sste32882hlb-datasheet
HP3336B Synthesizer/Level Generator repair - Page 1
Forum section: electronics / repair

author: tkamiya
author_rank: Super Contributor
timestamp: April 19, 2019, 09:16:45 pm
content: I have this new-to-me HP3336B Synthesizer/Level Generator that needs TLC.Overall, it works but in limited fashion. Power supply issue was there and it has been addressed. Voltages are all correct (within the accepted limit). No physical damage. All connections has been cleaned and deoxed. There is no obviously bad parts. No signs of physical damage. For its age, it's remarkably clean. I have the oddball WECO connector.Things I already fixed and how:+5V was 5.3V.Remote sensing wasn't going through connectors. Cleaned and reinserted.No output.Replaced coax between PCB and attenuator package.No output at certain attenuation.Removed and cleaned latching relay contact in Attenuator package.Other stuff I need help with:It has odd PLL situation. If frequency setting is xxx.x00.000.0, PLL is stable and signal is stable.If any of zeros are NOT zero, severe jitter as if PLL is not locking.Odd Attenuator function. Seems to be acting up. If output is larger than 33dB, levels are reasonable. If less than 33dB, signal actually gets stronger and repeats the decline again.I don't have the exact frequency where this happens as it seem to me random. But in lower frequencies, wave shape is not sine. Voltage crosses zero and goes up. Then there is this upside down triangle dip, then follows rest of the sine curve.I'm going through service manual but somehow, it is not as comprehensive as other HP manuals I've seen. Help is appreciated.

author: rf+tech
author_rank: Frequent Contributor
timestamp: April 20, 2019, 11:53:14 pm
content: tkamiya,QuoteThis behavior points to latching relay K3 not pulling in the 40 dB pad. K1 and K2 switch in 10 dB and 20 dB pads, respectively.RF+ Tech

author: tkamiya
author_rank: Super Contributor
timestamp: April 21, 2019, 11:38:30 am
content: Thank you. I hear relays clicking but at strange intervals. To start, I will have to clean contact points again and start from there.

author: rf+tech
author_rank: Frequent Contributor
timestamp: April 21, 2019, 03:17:26 pm
content: While you have the relays off, verify resistance ofbothcoils.The attenuator switching pattern should be consistent, with a 3 dB "offset." Since the maximum output level is +7 dBm, the 10 dB/step switching points will occur at -3, -13, -23, -33, -43, -53, -63 dBm; following weighted binary coded decimal logic.RF+ Tech
SMD cap alternative - motherboard has extra set of pads - Page 1
Forum section: electronics / repair

author: sirlemonhead
author_rank: Newbie
timestamp: March 28, 2019, 08:05:00 pm
content: Hi,I have an old computer motherboard from 1992 and I've just removed all the SMD capacitors as they were leaking, with the aim to replace them. I've noticed that each capacitor seems to have a second set of much larger pads. I've tested these for continuity and they appear to be alternative capacitor pads.You can see them here - the thin rectangular pads are from the original caps, the larger square ones are either to the side of or above/below the original pads.See picture:https://www.dropbox.com/s/1ryd6329nvzidxh/dellsmdcaps.jpg- pardon the flux gunk/residueI was wondering - why is this? Is this designed for an alternative capacitor type? If there were MLCCs or something longer lasting I could put on that would be great, especially as some of the alternative pads are oriented in much easier to access spaces than the original pads!Thanks!

author: wraper
author_rank: Unknown
timestamp: March 28, 2019, 08:08:14 pm
content: Most likely they are for tantalum SMD capacitors.

author: pbarton
author_rank: Frequent Contributor
timestamp: March 28, 2019, 08:56:04 pm
content: To reduce component sourcing risks...…https://www.eetimes.com/document.asp?doc_id=1121949#

author: LateLesley
author_rank: Frequent Contributor
timestamp: March 28, 2019, 09:14:50 pm
content: Quote from: pbarton on March 28, 2019, 08:56:04 pmThat's a very old article from June 1999.Capacitor prices on the rise againBy Bettyann Liotta, 06.18.99

author: pbarton
author_rank: Frequent Contributor
timestamp: March 28, 2019, 09:47:52 pm
content: That's a very old computer motherboard.The ‘buyers’ in manufacturers ‘Material Supply’ departments frequently experienced difficulty in securing supplies of certain components during the late 1990’s.It’s not uncommon to find that PCB layouts were designed to accommodate equivalent or substitute parts.

author: sirlemonhead
author_rank: Newbie
timestamp: April 02, 2019, 07:36:22 pm
content: Thanks, that's good to know!Would I be best off just using electrolytics? or is there anything else I can use worth considering over them or the tantalums?

author: Rasz
author_rank: Super Contributor
timestamp: April 23, 2019, 04:27:40 pm
content: Quote from: LateLesley on March 28, 2019, 09:14:50 pmhttps://www.arrow.com/en/research-and-events/articles/capacitor-shortage-going-into-2019war never changes
Systron Donner M5p15-30A Precision DC Voltage Source - Page 1
Forum section: electronics / repair

author: yordanov861
author_rank: Newbie
timestamp: April 20, 2019, 12:11:59 pm
content: I have a faulty Systron Donner m5p15-30A Precision DC VoltageSource. I need the digital schematic or any kind of drawings. Thanks in advance.

author: Vgkid
author_rank: Super Contributor
timestamp: April 20, 2019, 01:24:59 pm
content: Can you post a picture of the unit. I have never heard of it.

author: yordanov861
author_rank: Newbie
timestamp: April 20, 2019, 02:17:48 pm
content: This is the time machine !

author: Vgkid
author_rank: Super Contributor
timestamp: April 20, 2019, 10:52:03 pm
content: Wow, big unit. That doesn't look like it would be a factory power switch.What is the problem with it.

author: yordanov861
author_rank: Newbie
timestamp: April 21, 2019, 06:12:04 am
content: Should be factory made, I saw same picture onсе. I send it to a technishan. He changed some elements and now is giving 7.8 volts and is not regulating. Hi change on transistor (But i am not shure this is transistor) with simillar- original number (u1b 204- u is underlined). This machine is very old and all elements are difficult for finding.
Tips on de-soldering components off board which soldered on both sides - Page 1
Forum section: electronics / repair

author: Yamin
author_rank: Frequent Contributor
timestamp: April 19, 2019, 01:50:36 pm
content: Hi guys, could you share tips on how to de-solder components of board which is soldered on both sides. Mainly I have trouble with de-soldering IC's rather than components. I tried solder suckers, wicks -what only worked for me is heating and pulling but that sometimes causes the solder pads to lift or the trace to lift.What temperature would you recommend having the iron set at?Thanks in advance for the help.

author: testpoint1
author_rank: Frequent Contributor
timestamp: April 19, 2019, 02:35:31 pm
content: Quote from: Yamin on April 19, 2019, 01:50:36 pmif that is a DIP IC, you can use the HAKKO 474 or 808 desoldering gun.

author: bob91343
author_rank: Super Contributor
timestamp: April 20, 2019, 05:22:23 am
content: I have had great success with hot air desoldering. The equipment isn't costly and does the best job for me.

author: Mick
author_rank: Unknown
timestamp: April 20, 2019, 05:43:06 am
content: As testpoint1 points out, a vacuum de-soldering station makes easy work of DIP IC's.Zhongdi (http://www.china-zhongdi.com/product/station/desoldering/) or a rebrand, are cheap and fine for casual work. They offer different models but their much the same under the hood.Dave reviews one of their models (ZD985) here:

author: wasyoungonce
author_rank: Frequent Contributor
timestamp: April 21, 2019, 01:36:32 am
content: Honestly if they are PDIP ICs ...cut the legs use iron to heat pad pull out leftover with tweezers. If your replacing the IC....you ain't going to be using it again. Same with other thru hole parts.Other than that....thru hole de-soldering. I have a great old Royel vac de-solder/solder system but I really only use vac de-solder once per 6 months at best.If its SMD IC de-solder.....use chipquik. Its not cheap but if you're not using it much its worth it...in fact even if you are ...its worth it.FWIW
Rigol 1052e DSO - Page 1
Forum section: electronics / repair

author: Wolfgang Felber
author_rank: Newbie
timestamp: April 17, 2019, 12:12:29 am
content: :(Hi all, I am a newbie to this forum, I have problem with a Rigol 1052e, the power supply has just stopped working. I have gone through the usual suspects, changed all the electrolytics but still no life. I am getting 338 volts DC at the transformer, I thought that it should be an AC voltage after the TOP247yn offline switching unit. I have checked the other capacitors on the board by removing them and testing them, they all seem to be OK. I have managed to get a Schematic off the webb which was hand drawn but looks pretty accurate. I am leaning towards the TOP247yn as being the culprit but am open to suggestions. I know you probably need another Scope to test things. Open to suggestions. Enjoy the blog's. Thank you

author: Wolfgang Felber
author_rank: Newbie
timestamp: April 17, 2019, 05:39:17 am
content: Hi from the Newbie, I forgot to attach the Schematic of the 1052e, it doesnt show the switch, fuse 100uf filter cap. What I forgot to mention this morning was, the fuse did not blow the scope just went dead. hopefully someone can help, much appreciated.

author: Wolfgang Felber
author_rank: Newbie
timestamp: April 17, 2019, 06:32:54 am
content: Please find copy of the schematic for the Rigol 1052e

author: stj
author_rank: Super Contributor
timestamp: April 18, 2019, 11:34:12 am
content: TOP's are known to fail if they go into a startup-loop because of a dried startup capacitor.i replaced probably close to 100 while repairing set-top boxes for a shop.having said that, switching psu's often have a habit of cascade failing.that is, one thing fails and takes out a few other parts.so check all the diodes and resistors on the primary side of the transformer before you power it up again.and check the TOPswitch for shorts between the pins.

author: Wolfgang Felber
author_rank: Newbie
timestamp: April 21, 2019, 05:24:59 am
content: To the person who gave that information, Mate, I owe you a beer, thank you so much. You are a legend. I got it going by replacing the 2 meg resistor between the main cap and the top 247yn. A 48 cent part. ; ;

author: stj
author_rank: Super Contributor
timestamp: April 21, 2019, 09:49:42 am
content: good.glad nothing was burned in a way that would damage the pcb.

author: tautech
author_rank: Super Contributor
timestamp: April 21, 2019, 10:01:32 am
content: Quote from: Wolfgang Felber on April 21, 2019, 05:24:59 amThe SMPS controller IC's VCC HV dropper resistor or resistor chain is a common SMPS failure point and just as stj says, one of the things you must check.Another I've often found is the low value (20-50uF) VCC electrolytic cap, they go low value and/or high ESR.
Converting Milwaukee M18 charger from 110V to 220V - Page 1
Forum section: electronics / repair

author: wh_hsn
author_rank: Newbie
timestamp: October 07, 2018, 10:25:24 am
content: Hi,I looked everywhere for the circuit diagrams but the only good data I found was this:http://www.toolgir.ru/peredelka-zu-milwaukee-m12/My charger is M12-M18, 48-59-1812 (2015) & cutting the track & replacing the varistor & diode did the trick & it is working on 220V.Now I am working with a friend's Makita DC18RC S & I hope to get it converted too - I'll post my findings here.

author: scribble
author_rank: Contributor
timestamp: April 19, 2019, 11:39:47 pm
content: Cheers, too fast!I deleted my message as I missed the photo in the first posts webpage link (the .ru page) which showed where to cutAt least it's now here for anyone else searching in the futureEdit: Replaced varistor with a TVR14681 scavenged from something else, cut the track about 5mm wide and it charges without complaint on 230v.
Retron 3 Retro Gaming Clone (KA7805) - Page 1
Forum section: electronics / repair

author: NviGate
author_rank: Newbie
timestamp: April 23, 2019, 07:45:05 am
content: Hi all. I've been a subscriber on Dave's YouTube channel and finally figured I would contribute to the forum. I've currently got a Retron 3 Gaming Console to bits and need some advice on what I believe is a really bad design choice.This is a multi system emulator that uses original game cartridges. This one doesn't work. No power. I watched a youtube video where someone fixed his retron by replacing the KA7805 (Fairchild Semiconductor) voltage regulator. I felt near that area and huge amounts of heat, enough that the swab of glue they left was melting. So I desoldered the component and have located a replacement, but if you look in my photo that long aluminium channel that is only 1mm thin, is what they used to cool the chip. That doesn't seem anywhere near what I would consider decent cooling for a 5V 1A chip. Plus, the chip stands slightly bent over with the solder the only thing which supports itself and the aluminium "heatsink"Don't mind the cables I have soldered there, was using those to do some tests, easier to probe wires than the solder pads.I was wondering if I should get proper gauge wire to handle the current and move the chip to an area of the case where there is room to put a decent heatsink on it. Or wire a 5V fan to keep air moving in that area. Is there other options you would consider?I'm wanting to restore this and fix some of the common issues. It seems lots of these Retron consoles were...cheaply made. Not that I don't mind, cause I know how to solder, look up replacements parts etc. Although I have a hard time with resistor codes. They scare me. Someone should invent an app where you take a photo of a resistor color band and it decodes it for you. ;-)

author: kosomsk
author_rank: Regular Contributor
timestamp: April 23, 2019, 10:24:27 am
content: Hi! If you need cooling 5V linear regulator, then forget about this.Change it to DC/DC and this part be cold
testing help - Page 1
Forum section: electronics / repair

author: skumar
author_rank: Newbie
timestamp: April 19, 2019, 06:51:33 am
content: Sir i need helpi connected smps, AC-DC- output was 5v 0.5 A, but all mcbs tripped of household, even whole my swtich burnedhow to do protection and set up testing lab for these if i take 2Ado i need to conNect MCB or whtplz help

author: anewmanx
author_rank: Contributor
timestamp: April 19, 2019, 08:21:43 am
content: I’m not sure I fully understand what you are asking. It sounds like your power supply has a dead short. You could make a dim bulb tester to act as a current limiter and then try to find the short, especially if you can bring it up slowly on a variac. A safer bet would be to try to find it with a multimeter first. Your most likely culprit will be an electrolytic capacitor that is shorted internally. Likely you have damaged components now.

author: skumar
author_rank: Newbie
timestamp: April 19, 2019, 08:28:46 am
content: ok thanksI also want to know what is the basic of testing, like i m afraid if i testing 100 w or 2 kw , have seen people in lab use MCB as protectionSo how should i set up testing wiring, for whether 100w or 5 kwSir ,, now my question what should be protection in lab if i just conect input output for high power,( not asking how to test), asking protection sir

author: PKTKS
author_rank: Super Contributor
timestamp: April 19, 2019, 01:54:02 pm
content: The TIP of a BULB DIM is indeed a GOLDEN RULE.Don't - JUST DON'T - TURN ON A FAULTY DEVICE WITHOUT A DIM BULBThe POWER is also very important - use a SET OF BULBs - which the SUMis equivalent to the power of DUT - e.g. the BULBs power is equal to thedevice power.Put the DIMs in series with the line of the device and try to turn it onit the bulb lits the device is dead shorted.In this case to proceed is very handy a VARIAC as wellPaul

author: skumar
author_rank: Newbie
timestamp: April 19, 2019, 02:47:18 pm
content: ok thanks
MSO7014B bad encoder - Page 1
Forum section: electronics / repair

author: Justincase1979
author_rank: Contributor
timestamp: April 17, 2019, 05:13:00 pm
content: Hi everyoneI just purchased an Agilent MSO7014B, and for the most part it works great. But there is an issue with the knobs for the trigger level as well as the Measure knob. When turning the knobs slowly they work ok, but if I turn them quickly they hardly respond at all, so I figured the encoders are the problem.Do anyone know if it is possible/easy to clean these, like the ones in for example the E3646A power supply?If not, do anyone know of a suitable replacement encoder? I checked and it does not seem like the encoders are available from Keysight!?Any feedback would be greatly appreciated.

author: SilverSolder
author_rank: Super Contributor
timestamp: April 17, 2019, 11:45:12 pm
content: I don't have that exact piece of equipment, but in the past I have seen rotary encoders respond positively to a small dose of Deoxit.

author: bitseeker
author_rank: Super Contributor
timestamp: April 18, 2019, 05:45:18 am
content: Open it up and see if the encoders are similar. If they're held together with tabs like the HP power supplies, function generators, etc., then give one a try. Also, it's helpful to post some pics once you've gotten inside.

author: Justincase1979
author_rank: Contributor
timestamp: April 18, 2019, 07:42:53 pm
content: Quote from: bitseeker on April 18, 2019, 05:45:18 amWill do, was just hoping someone else had already been there. At least the picture of the encoders in the service manual show them with the same tabs as found on other HP/agilent equipment, so there is some hope this will be a quick fix.Sent from my Pixel 2 using Tapatalk

author: bitseeker
author_rank: Super Contributor
timestamp: April 18, 2019, 09:44:15 pm
content: Sounds like a high probability it's going to be an easy clean up. I've done a bunch of them, but not on a scope (yet).
Lenovo Y50 LVDS connector - Page 1
Forum section: electronics / repair

author: ealex
author_rank: Frequent Contributor
timestamp: April 18, 2019, 10:24:36 am
content: helloi'm trying to find the connector from the image at some distributors like mouser or farnell (it's the display cable, the burnt pins are the backlight power pins, the previous owner was not careful and tried connecting it with the battery still in the system):according to the schematichttp://kythuatphancung.vn/uploads/download/99d76_Compal_LA-B111P.pdfpage 22, it's an "ACES 50398-04041-001" connectorsearching for that part number returned one ebay seller that does not ship over here, and i've found another name for it : "50398-04041-001 and LVD-A40SFYG-TP" (ebay:https://www.ebay.com/itm/312536974591?ViewItem=&item=312536974591)i've looked at farnell and the only one i found is Hirose DF36A-40S-0.4V(51) but it does not match the metal frameat mouser i could find Molex 501083-4010 but it does not match the metal frame, and it's mirroredany hints on how to search for a matching connector ? or where i can find one ?( i can find the pairing cable on the local market, at a decent price but no chance for the connector)

author: ealex
author_rank: Frequent Contributor
timestamp: April 18, 2019, 12:16:45 pm
content: some more searching and i managed to find out a list of equivalents:HONDA: LVD-A40SFYG-TP+ACES: 50398-04041-001ENTERY: 0921K-Y40C-00L

author: ealex
author_rank: Frequent Contributor
timestamp: April 19, 2019, 11:39:30 am
content: quick update: it never hurts to ask, the US seller shipped the connector my way.I've managed to clean up the board enough to get the board to boot and partially mate that connector => got to the bios screen, with a working back-light - enough pins remained for a quick test, it uses the connector metal frame for an extra groundi had to solder some wires on the power connector - i don't have the adapter and i've used my lab psu to start it.a quick video filmed with an andostar ADSM302. you can see my "hunting" for the Z axis, but once I find a zero i can use it - not as good as a decent stereo microscope, but good enough for short jobshttps://www.youtube.com/watch?v=0LN8NWA-h6o&feature=youtu.be
Mini PC repair help - Page 1
Forum section: electronics / repair

author: BinderTronics
author_rank: Newbie
timestamp: April 19, 2019, 11:25:39 am
content: Hi I was wondering if anyone can help me source schematics or chips for a Beelink bt3 pro ver3 0,Nexbox t11 and a z83 II (no brand markings) mini PCs. Thay don't turn on.I have opened the Beelink and probed it. The 1.8V line is not presant on the board (most of the time).The 5V to the USB2 and USB3 are there. Have not found a 3.3V line (assuming it is dead).Strange thing is that the 1.8V line returns sometimes after probing the board with continuitytesting (found this out by buring my finger on the cpu). Got a chip that is marked AMCJ445(its's a QFN)that takes the 12V supply and steps it down to 5V and 5.5V. The 1.8V seems to come from the AMCJ445 aswell.Haven't been able to find any information on the AMCJ445 chip.There is a AXP2880 PMIC as well that is dead in water but is seems to need a 1.8V to turn on (got a datasheet).Haven't found a connection to the power button but CPU does heatup when I press it when 1.8V is there (no image).Board seems good with no shorts or water damage. Haven't had the guts to reflow anything yet.Any assistance would be greatly appreciated.AXP2880 datasheet.http://download.icxbk.com/201707/cfe88ee7ef01eed7a4586ce340165da0.pdf
rohde schwarz SML 02 repair help please. - Page 1
Forum section: electronics / repair

author: eurgenca
author_rank: Regular Contributor
timestamp: December 02, 2018, 10:48:46 pm
content: Hello.I was looking for repair tip for sig. generator sml02 and found this site. So first I want to say Hello to all of you.So I bought this sml on ebay with broken LCD. After replacing with new I can see that I have more problemsAfter powering up I get error msg.Module (0/CPU)Missing data block10401 / freq data extThen sml finish booting up and under error page I have 1 stored error.315 configuration memory lost; EEPROM dataI check service manual and all info that I can get is that one or more data block is missing. But no info how to repair this. I try with calibration and all tests pass, but error remain. Can someone help me with this error.Thanks and regards, Sebastijan.

author: eurgenca
author_rank: Regular Contributor
timestamp: December 04, 2018, 07:02:25 am
content: Hello, again.I found in manual that exist software SML SERVICE UTILITY, but I can't find it on the net. If someone here have this SW or link where to download, will be very happy.Thanks, Sebastijan.

author: analogRF
author_rank: Super Contributor
timestamp: April 19, 2019, 02:10:24 pm
content: Quote from: eurgenca on December 04, 2018, 07:02:25 amwere you able to find that software or to solve the problem with the instrument?

author: eurgenca
author_rank: Regular Contributor
timestamp: April 20, 2019, 08:31:44 am
content: Hello.This SW is for service center only, so probably nobady make a copy and release it on net.I figure out that configuration error is due to wrong firmware update, but benefit is that frequency go to 3.3Ghz. So it is basically SML 03.Regards, Seba.
Sony a7R ii Missing component identification  - Page 1
Forum section: electronics / repair

author: jerb
author_rank: Contributor
timestamp: April 21, 2019, 04:51:19 am
content: Need help figuring out what this is?I think it may be an inductor given how it looks but i just want to get a second opinion.

author: LateLesley
author_rank: Frequent Contributor
timestamp: April 21, 2019, 06:43:25 am
content: While I can't help with the component ID (it's hard to tell with these things), I did find a datasheet for the chip it's beside. I'm thinking if you can trace tracks from the chip, it may offer clues to what the missing part is, from the example circuit??http://www.ti.com/lit/ds/symlink/tps63060.pdfPage 12 is the example circuit, page 3 is the pinout.

author: jerb
author_rank: Contributor
timestamp: April 21, 2019, 08:23:04 am
content: I was able to figure out that it was indeed an inductor. I probed the two sides of the missing component and neither went to ground which confirmed my suspicion. I was able to remove one from another camera board and it's now functioning normally. I appreciate you taking the time to give me your input!
Need help for a repair for the Rigol DG1022A - Page 1
Forum section: electronics / repair

author: thephantom1492
author_rank: Contributor
timestamp: March 17, 2019, 05:30:39 am
content: Hello everyoneI need help to figure out a proper replacement for the common mode choke for the channel 1 of my signal generator.Mine is just... a dead short so no mesurement is possible.<=== This is the choke, as seen there: ===>edit: need mostly the inductance value, or a likelly range...edit 2: specify siggen

author: thedoc298
author_rank: Contributor
timestamp: March 17, 2019, 12:00:43 pm
content: It should measure as dead short or very low. What is the problem with scope...?

author: thephantom1492
author_rank: Contributor
timestamp: March 17, 2019, 10:42:38 pm
content: dead short on all 4 pins on that common mode choke. Channel 1 output is null.Removed the choke and replaced by 2 wires and the siggen work, but obiviously the removal of a component is not ideal.And, that choke is short on all pins.edit: the DG1022A is a siggen, not a scope

author: thedoc298
author_rank: Contributor
timestamp: March 18, 2019, 03:04:06 am
content: So the choke was shorted, and you replaced the shorted choke with wires (another short) and it works.So don't you think your choke is open and not shorted..?

author: Dacke
author_rank: Regular Contributor
timestamp: March 18, 2019, 03:40:21 am
content: This is the one I used in my DG1022 as I had the same thing happen to mine:https://www.digikey.com/product-detail/en/wurth-electronics-inc/744235601/732-4221-1-ND/3672769And yeah, the windings in the choke got blown open due to my own stupidity. The sig gen works fine now.

author: thephantom1492
author_rank: Contributor
timestamp: March 18, 2019, 04:23:40 am
content: Here mine had started to be weird at time, showing overload at time that I wondered why... and then I fed 35V from a subwoofer to the ground (fricking amp seems to be positivelly grounded, or something, the red was the ground !I hope it will fix the other issue I had at the same time.edit: thanks!

author: thephantom1492
author_rank: Contributor
timestamp: March 20, 2019, 04:08:36 am
content: Good news! I got a reply from rigol itself!That choke is ACM4532-901-2P, an alternative is ACM4532-801-2P.Both currently unavailable, we'll see if it come stock soon.

author: Housedad
author_rank: Frequent Contributor
timestamp: March 21, 2019, 02:00:56 am
content: Here ya go:https://www.ebay.com/itm/5PCS-X-ACM4532-801-2P-T001-4532L-TDK/332594598263?hash=item4d702ed177:g:H1IAAOSwqblasvQ6

author: thephantom1492
author_rank: Contributor
timestamp: April 18, 2019, 05:00:24 am
content: A bit old (been quite busy) but for future reference:ACM4532-901-2PACM: series4532: size, 4.5x3.2mm901: impedance at 100MHz: 900Ω2P: number of linesI can't find the ACM4532-901-2P exact specs, but the 801 is:800Ω@100MHz, DC resistance: 100mΩ, rated current: 1A, rated voltage: 50V
High Power LASER LED current switch transistors and thermal foam - Page 1
Forum section: electronics / repair

author: msimunic
author_rank: Contributor
timestamp: April 17, 2019, 06:24:16 pm
content: Hi,I have a board which is suspected to produce intermittent (random) LASER LED current drive issues.Board have weird thermal foam-like material over many power switching components.Anybody knows what this blue material could be?Also, I can't find which smd device could be in this smd thin metal case (IVR 6638 A4CJ 1229).The Logo of part producer is hatched circle.

author: shakalnokturn
author_rank: Super Contributor
timestamp: April 17, 2019, 09:00:52 pm
content: https://pdf1.alldatasheet.com/datasheet-pdf/view/211259/IRF/IRF6638PBF.html
smps high pitch click sound once on load - Page 1
Forum section: electronics / repair

author: elor
author_rank: Contributor
timestamp: April 16, 2019, 09:17:01 am
content: i dont have many experience in fixing smpsand would appreciate any kind of lead from you guysthis power supply belongs to my tec controlled camera and supply 12v ,-12v ,5v ,tec and thermistorit fails under load of the camera making high pitch click noise oncethere is another section that connects to the tec deriver (pid-1500 by wavelength electronics with a window comparator ltc1042)adding couple of pictures

author: kosomsk
author_rank: Regular Contributor
timestamp: April 16, 2019, 05:51:34 pm
content: ShalomChange shorted part & try to load repaired psu

author: wasyoungonce
author_rank: Frequent Contributor
timestamp: April 17, 2019, 10:17:39 am
content: Look there is not a lot in it. A main switching fet, a TL431 and anther transistor on the hot and rectifier. You should be able to check these with a multimeter but be aware the fet will be in series with the primary hot so you may back measure thru the winding. There is a small Tantalum C2 and diode and diode D3 and resistor R2. Check these especially tantalum's...maybe change on speck. These usually form an oscillator cct that drives the FET and chops the rectified "tank" voltage on the coil hot side. The opto feeds back from the cold side. Oh there is glue or something around R2 can you clean away.Check the cold side diodes wit ha multimeter again these will be across windings but they will have differing readings one way compared to the other on diode test or low ohms. Might be also regulators on this side...cannot see them in the pics.Also check the electros on the cold side rails. More than likely the fault is "bad caps"....electros that the ESR has gone high which loads the secondary down causing feedback to turn off the oscillator. Bad electros in a switchmode is a common fault. They only way to test them is to use an esr meter or replace on spec with low esr new caps.If the PSU is older....i'd be doing this as a matter of course. Oh by the way what camera is it....a TEC cooled astro camera?

author: elor
author_rank: Contributor
timestamp: April 17, 2019, 10:30:32 am
content: sure its an old swir camera 320x240i think ill try to reverse engineer it as i need it to run from dc anyhowill try to update this post as i go12 pin hirose plug1 -- gnd2 -- (-12v)3 -- gnd4 -- 12v5 -- gnd6 -- 5v7 -- tec +8 -- tec -9 -- thermistor -10 -- thermistor +11 -- nc12 -- ncmy bom so far:lm2937et -- 5vlm2940ct -- 12vlm2940t -- tec power ~7vptn78000a -- (-12v)htc-1500/pid-1500ltc1042caps, res etc as needed

author: kosomsk
author_rank: Regular Contributor
timestamp: April 18, 2019, 03:12:42 pm
content: Easier to take the Chines DC/AC inverterer and use the camera according to the scheme 12V->DC/AC( to ~220)->Camera's PSU.