hybridfree/eevblog-posts huggingface dataset:
Agilent 33210a  Components not identified. - Page 1
Forum section: electronics / repair

author: jocelio
author_rank: Newbie
timestamp: January 15, 2017, 01:32:36 pm
content: After an error of operation from my part grounding damaged the 3 components as shown in the photo it is working from to see that it is normally generating the components then short .

author: bktemp
author_rank: Super Contributor
timestamp: January 15, 2017, 01:46:17 pm
content: One part seems to be a tranformer or a common mode choke. So measuring a short accross its pins could be normal.The other ones are TVS diodes, based on the marking GFT they should be SMCJ43A.

author: jocelio
author_rank: Newbie
timestamp: January 15, 2017, 02:17:54 pm
content: What seems to be a type of choke is giving short circuit in all the send and when I put it back simply it eliminates the pwm it is in short posivo with negative preventing any type of pwm when I take it back the pwm and the generator Works normally the diode seems to be more of a type of varistor and is in short. And has no polarity.

author: Andy Watson
author_rank: Super Contributor
timestamp: January 15, 2017, 02:38:04 pm
content: The manual for the 33220A indicates that the four-pin device is, as BK suggests, a common mode T1101. The manufacturer's (TDK) part number is ACM4532-801-2P, I would expect a similar device in the 33210A.

author: jocelio
author_rank: Newbie
timestamp: January 15, 2017, 02:49:19 pm
content: Quote from: Andy Watson on January 15, 2017, 02:38:04 pmHere in Brazil ACM4532-801-2P does not exist for sale what can I do? Already the vr602 FAD27 would be possible a substitution of the components for another type of component would have some type of solution for me being that I wanted to preserve the safety of the equipment .. because here in Brazil the prices are abusive.

author: Andy Watson
author_rank: Super Contributor
timestamp: January 15, 2017, 03:52:12 pm
content: Looks like it's obsolete!http://uk.rs-online.com/web/p/signal-filters/5474850/Go with the nearest part that you can find. 4532 is the physical size of the device. 801 is the value of interest, it indicates it is 800\$\Omega\$ impedance at 100MHz. 2P indicates two pole (rather than 3 pole/lines).For low quantities ebay can sometimes be useful.
Agilent 16702 logic analyzer  PSU fail - Page 1
Forum section: electronics / repair

author: Daxxin
author_rank: Regular Contributor
timestamp: January 08, 2017, 10:00:43 am
content: PSU autec 552-1362A pcb rev. .X3 clicking wont start , any schematic beforte to check ?

author: bsalai
author_rank: Regular Contributor
timestamp: January 08, 2017, 11:33:37 am
content: Quote from: Daxxin on January 08, 2017, 10:31:31 amI've not worked on this one, but I've solved a similar sounding problem in other power supplies in HP scopes by removing the electrolytic capacitors, cleaning the PC board under them (even if you don't see anything, and installing new caps. Apparently some of the caps leak.Good luck.Sent from my iPhone using Tapatalk

author: mos6502
author_rank: Frequent Contributor
timestamp: January 08, 2017, 04:07:54 pm
content: Clicking means that some protection circuit is active, either overcurrent or overvoltage. You need to trace the circuitry going to the control pin of the TOPSwitch and see what is making it stop. Randomly replacing parts is unlikely to result in success.

author: Daxxin
author_rank: Regular Contributor
timestamp: January 15, 2017, 02:51:08 pm
content: Tried to draw schematic from board , maybe there is errors , got short SCR1 , SCR2 and D35 modules input 300Vcc
Marantz SR 1040, burning new fuses. Amplitude limiting system? - Page 1
Forum section: electronics / repair

author: manfredkallfass
author_rank: Newbie
timestamp: January 14, 2017, 03:15:44 pm
content: Dear all,I bought a marantz 75 SR 1040 amp 2 years ago.After 1 year it started "muting" itself for some seconds, mostly when the volume was a little bit high (not THAT high tho). It muted with a sort of "click" - the same sound of when it turns on or off.It looked like it actually went off during the peaks of amplitude...like a volume protection.Then at one point it just went bananas and it won't play anymore. It did not even turn on.I changed one of the fuse, which was burnt, and when i turned it on again it burnt the new fuse.I have had no time to work on it for one year. Now i have a little time and I would know if your knowledge can let me understand where to start from to repair it...(maybe capacitors are gone...?). If needed i can send you some more details, pictures, ...The speakers I was using were quit bad, found in the trash: 8 ohm, they handle 10 to 90 W each. 98db/1w/1m as sensitivity if that matters... One of them has a destroyed woofer.Thank you, all the best,manf

author: mzacharias
author_rank: Frequent Contributor
timestamp: January 14, 2017, 08:13:00 pm
content: It was an exceptionally bad idea to use known defective speakers. You now have at a minimum one amplifier channel blown (possibly both channels).The output transistors for at least the one channel are now shorted; quite possibly other parts such as driver transistors, resistors, diodes, bias transistor, etc damaged as well.Easy job for an experienced technician, probably challenging for a novice.

author: manfredkallfass
author_rank: Newbie
timestamp: January 15, 2017, 11:31:39 am
content: Thanks for the answer, not very encouraging but I will try to look at it if i get some time. Or get a new amp. And a new speaker.
Tektronix TDS580D A10 acquisition board MM9599 UCC (Solved) - Page 1
Forum section: electronics / repair

author: pmax65
author_rank: Newbie
timestamp: January 12, 2017, 11:05:12 am
content: Hi there, I experienced a failure on my TDS580D DSO.The error logger reports the DAC2 Varigain DAC too high, and indeed the CH2 hybrid attenuator/preamplifier variable gain input is set to its maximum, and its output correctly is about 40% higher than what it should be.I checked the CH2 attenuator/preamplifier anyways swapping it with CH3 and nothing changed, confirming that the attenuator/preamplifier is good.Since the circuitry after the attenuator/preamplifier output is changed from the TDS520B schematics available on the Internet, I would like to know if someone out of here had any information about that circuitry.In particular, I would like to know what is the name of the integrated circuit which seems to embed the sampling triggers logic and maybe the 4 ADCs which has the heatsink sticked on it.I also would appreciate any information about the National semiconductor’s BGAs named MM9599-UCC.Have a great day.Massimo

author: PartialDischarge
author_rank: Super Contributor
timestamp: January 12, 2017, 11:20:24 am
content: IIRC in my TDS744 those chips (trigger logic, and ADCs) are custom made parts and pretty much every big IC you see in that board is.

author: pmax65
author_rank: Newbie
timestamp: January 12, 2017, 01:28:21 pm
content: I there,thank you for your interest in this issue.Yes, I know that, I just looking for any info (such as pinouts) about those chips for planning a diagnostic strategy of the signals between them.Have a great 2017Massimo

author: pmax65
author_rank: Newbie
timestamp: January 14, 2017, 03:33:21 pm
content: Hi there,I finally fixed the DSO.It was a silly TL074 named U702 placed close to the hot IC U700, which it look like it has embedded the trigger logic, the sample & hold circuitry and the 4 ADCs that until version C were split in 5 different ICs.In few words U702 in the D series DSO does the work of U701 detailed in pages 9 to 12 of the schematic included into the file "TDS520B_Digitizing_Oscilloscope_Component_Manual.pdf".The output driving the ADC channel 2 reference input had the output stuck to 4V.Have a great day and an happy 2017.Massimo
Find datasheet for a SMD code - Page 1
Forum section: electronics / repair

author: RoGeorge
author_rank: Super Contributor
timestamp: January 13, 2017, 04:24:48 pm
content: The attached picture is from a Li-Ion battery charger that came with a fake "Sony" video camera. Being a fake camera, I suspect the charger might not be very safe. I would like to use it as a generic charger for other Li-Ion batteries, so I took a look inside. The charger is powered by a 5V generic wall adapter, and the Red and Black wires are going to the battery. Floating voltage is 4.15V. A Red/Green LED lights Red when charging and green when battery voltage is 4.15V (or no battery connected).I am NOT interested in Li-Ion charging or safety advice here, the question is all about identifying SMD datasheets.Can someone help me to identify the exact datasheet, please? The closest one I found so far (but its not a perfect match):http://www.s-manuals.com/pdf/datasheet/e/c/ec49016_20060518_ecmos.pdf1. The case is about 3mm wide (maybe a SOT-23-5), but what IC is in the picture? I need its datasheet.2. How do you find datasheets for SMD parts in general?Most of the time google doesn't help very much.3. Any good links for SMD identifying?

author: bktemp
author_rank: Super Contributor
timestamp: January 13, 2017, 07:30:23 pm
content: SE9016:http://downloads.qi-hardware.com/hardware/datasheets/qi_lb60/U5~SE9016.pdfIf you enter 016i sot23-5 into google you find many links to SE9016 battery charger. The pinout seems so match the layout on the pcb.Using only the marking code google rarely finds the datasheet. But Marking code + package or marking code + function (like battery charger, diode, voltage reference) often leads to the correct datasheet.
Philips TV power supply - PLHL-T722A or PLHC-T81A - component D106A? - Page 1
Forum section: electronics / repair

author: 4cx10000
author_rank: Regular Contributor
timestamp: January 13, 2017, 03:30:20 pm
content: Hi!A friend of mine came in with a power supply board from a Philips TV 47PFL9603H/10. He also brought a service manual which at a first glance seemed to be the right one, but non of PSU:s in the manual was even close to that one on my workbench. On the board there is one burnt resistor - R5 120ohms - and a couple of 1N4007 in a string - 4 in total. There is also a 7-pin switch IC - FSQ510 - that has also went up in smoke. Well, this D106A is connected across the primary side of a small transformer which looks like it is part of standby part of the PSU. Looking on the silkscreen at D106A location, it shows a bi-directional suppressor diode (TVS). Marking on this component is T2D82, anyone?
Hantek 6022E fault? - Page 1
Forum section: electronics / repair

author: helpme123
author_rank: Newbie
timestamp: January 14, 2017, 05:38:51 pm
content: Hello,I was working on a project with STM32 discovery when the said piece of Chinese equipment failed on me. As I was monitoring outputs, I went to recompile the code when the Hantek failed. The software froze, and after that i got no signal on the scope. The STM is working fine, so i don't think anything shorted out. I also always work with only one ground on the probes, as a safety measure.I tried restarting the computer, reinstalling the software, and using different USB ports.Hantek seems to be flashing some fault code on it's front (and only) LED (Red, Red, Red, Red, Red, Green). I tried searching online for that pattern, but found nothing. I am suspecting it might be a driver problem, but I might be wrong.Any help would be much appreciated, thank you in advance.
Help identifying SMD Component - Vehicle Audio Amplifier  - Page 1
Forum section: electronics / repair

author: ryann
author_rank: Contributor
timestamp: January 07, 2017, 04:43:29 pm
content: I'm trying to repair my Rockford Fosgate P300-10 amp+10" sub that I've had installed in my car. The fail-state was remote input started outputting power, which kept all my accessory power components on (around 8V), and the amplifier remained on all the time.I believe I've narrowed it down to a transistor. The SMD code is 2TN. It's in a SOT23 package. What I believe to be the base and emitter is shorted with 4 Ohms of resistance, either way I measure it. I'm taking a stab in the dark (only debugged do far for an hour).I have attached how I think the circuit works. Q1 is an guess at what the component is, since I have not been able to identify it. T1 is acting as a diode. It's an NXP BCP56 NPN diode.The problem I've identified is between TP1 and TP2 in the schematic, I measure 4 Ohms, no matter the direction I measure, meaning to me, that the transistor has failed. I have removed the transistor from the circuit and applied power back to the circuit. The amp remains off (good thing).So, I am naively hoping that replacing Q1 in the schematic (SMD part 2TN) will fix it. Problem is, I cannot identify it. Any help?

author: ryann
author_rank: Contributor
timestamp: January 07, 2017, 06:22:08 pm
content: That transistor was just the tip of the iceberg. I moved another 2TN transistor from one of the other Auto Power On switch inputs and it still turned on without any REM input.

author: jkf1000
author_rank: Regular Contributor
timestamp: January 12, 2017, 12:12:23 am
content: Thr REM input from the vehicle is normally active high. The schematic as it is drawn would not operate unless the diode was in the opposite orientation unless I am reading something wrong?. Karl
Meanwell SE-600-12 Fan Control - Page 1
Forum section: electronics / repair

author: EIKA
author_rank: Contributor
timestamp: January 11, 2017, 07:44:42 pm
content: Hi all!I want to mod Meanwell SE-600-12 to make it less noisy. I no need all 600W of power, I will use only 35-40% as maximum. But I come across with a problem - it run fan all the time, including when not loaded and absolutely cold. It’s extremely nosy like 19” server. I want to lower fan’s rpm or something like this.I Googled for SE series schematics, but absolutely nothing.Does anybody have schematics or know MeanWell / NES models with similar schematics or even fan control?

author: EIKA
author_rank: Contributor
timestamp: January 11, 2017, 09:44:15 pm
content: Okay guys, I can't wait for schematics.Here is my solution for MeanWell SE-600-R16VAI.It's manual, yes. But it will work for me, because I don't plan to load PS for more than 250W. And advantage is its 100% reversibility. Nothing was cutted, destroyed or even soldered. All you need is Zalman Fan Mate or similar fan controlller with DC regulation in 5-13 V range, a few centimeters of heatshrink, knife and pliers.Just remove 2-pin connector body from PS and remove male pins from controller's connetor and connect red and black wires accordingly. Leave white (yellow) wire not connected. And here you go!BTW, real fan voltage is 14.7 VDC when nominal fan voltage is 12 VDC, and it's a reason why fan as noisy as rack server.
hp 652A Test Oscillator  - Page 1
Forum section: electronics / repair

author: mdbarg
author_rank: Newbie
timestamp: January 11, 2017, 01:19:23 am
content: For fun and a good learning experience, I just started evaluation and repair of an old hp 652A Test Oscillator (circa late 60s) and would like to share lessons learned with anyone who is doing the same or has an interest. First observations: Distorted sinusoid output, so I am looking at the oscillator PCB, first. The unit has old style Sprague axial electrolytic caps, which I will likely need to replace once I test their ESR and D. The unit has double sided through hole PCBs with excellent hp workmanship.
Wee Megger - no full deflection to infinity - Page 1
Forum section: electronics / repair

author: jeroen79
author_rank: Frequent Contributor
timestamp: January 08, 2017, 08:08:51 pm
content: I found an old 'Wee' Megger that has a slight flaw.With nothing or a high resistance (10M?) connected the needle does not fully deflect but stops near 4M?.1M? reads correct.A short will also fully deflect the needle to zero.I found nothing stopping or slowing the needle mechanically.If I pass current through the coils I can also fully deflect it.Open circuit output meets the required 500V.The circuit:A is the (wirewound) resistor for the deflecting coil.D is the resistor for the control coil.B and C are a capacitor and resistor to stabilize the inductor's output.Hereit says that A and D should be 100k? each.B and C should be 0.1mFD (=100nF?) and 47k?.What I measured:LD 260? (deflecting coil)LC 115? (control coil)A 49.6k?B 0.44uFC 5.27k?D 210k?This does not match the specified 100k?.Is it possible for these wirewound resistors to somehow change?Weird thing is that one is twice as lage and the other twice as small.My theory:The higher resistance on the control coil and the lower resistance for the deflecting coil will make the latter much stronger so it will favour the zero side over the infinity side.Am I right?Would the solution be to replace the old resistors with new 100k? ones?As they will be loaded at 500V they should be at least 2.5W rated, right?The inside with parts marked. (not mine)The bridge over the meter movement is the common for LC and LD and is also connected to the generator and the capacitor.The two coils have separate connections at the bottom and these go to the resistors.

author: iDevice
author_rank: Regular Contributor
timestamp: January 10, 2017, 09:50:11 pm
content: Mine does that as well.I don't think it's normal though, but besides that, it is still accurate on the remaining of the scale.Are you sure you have the schematics of your model ?The one you show seems odd.The early versions were driven with a DC generator and shouldn't have a capacitor I guess.Later ones (Since the 50' if I remember) switched to an alternator (which I happen to have) and the picture you show is from this later alternator version.On this picture (again from memory) A & D are the two selenium rectifiers and B is the dual capacitor, all mounted as a multiplier.I can dig in my documentation to see if I find more info but I restored mine a few years ago so I'm not sure.

author: mmagin
author_rank: Frequent Contributor
timestamp: January 11, 2017, 12:41:47 am
content: The resistor in the picture that I can see (C) looks like a carbon comp resistor, not wirewound. Those are well known for varying with age.
Hameg HM507 Schematic - Page 1
Forum section: electronics / repair

author: And
author_rank: Newbie
timestamp: January 07, 2017, 10:06:32 pm
content: Good Morning and HNYWhy not exist download for Hameg HM507 Schematic or Service Manual in all internet?Can everybody help me?Thank you.And

author: Falkra
author_rank: Regular Contributor
timestamp: January 08, 2017, 02:50:05 pm
content: Hi, it can be found here, but the website looks down at the moment :http://elektrotanya.com/hameg_hm507_oscilloscope_um.pdf/download.html

author: kripton2035
author_rank: Super Contributor
timestamp: January 08, 2017, 03:26:20 pm
content: it is the user manual, not the service manual ...

author: tautech
author_rank: Super Contributor
timestamp: January 08, 2017, 07:17:25 pm
content: Quote from: kripton2035 on January 08, 2017, 03:26:20 pmCorrect, it is and the giveaway is that it's too small file size.Quote from: Falkra on January 08, 2017, 02:50:05 pmWhenever you access elektrotanya for manuals there will be near the bottom of the page "processing" that does change to "Get Manual" after some time.Quote from: And on January 07, 2017, 10:06:32 pmIn other Hameg SM requests I've seen the advice is to email Hameg for a copy and they seem happy to oblige.Let us know how you get on please.

author: JFJ
author_rank: Regular Contributor
timestamp: January 08, 2017, 11:04:17 pm
content: Quote from: Falkra on January 08, 2017, 02:50:05 pmThat user manual is available, in various languages, directly from the Rohde & Schwarz web site:https://cdn.rohde-schwarz.com/hameg-archive/HM507_english.pdfhttps://cdn.rohde-schwarz.com/hameg-archive/HM507_deutsch.pdfhttps://cdn.rohde-schwarz.com/hameg-archive/HM507_espanol.pdfhttps://cdn.rohde-schwarz.com/hameg-archive/HM507_francais.pdf

author: Falkra
author_rank: Regular Contributor
timestamp: January 10, 2017, 08:47:21 pm
content: Quote from: tautech on January 08, 2017, 07:17:25 pmYes, this is ok, and the usual way it works. I had no page at all when I went, then it was back online.
Tektronix 576 HV Power Supply troubleshooting HV Probe Recommendations - Page 1
Forum section: electronics / repair

author: Johnny10
author_rank: Frequent Contributor
timestamp: January 10, 2017, 02:01:03 pm
content: I recently acquired a Tektronix 576 Curve Tracer B28xxxx serial number I believe from late 60's.The CRT image flashes and dims and sometimes drifts after initial warm-up.I checked all LV voltages and all measure within spec. and stay in proper range throughout my problem.The 225 VDC measures from 199VDC through to 177VDC.I have Fluke 87 for measuring voltages and cannot measure 4000 volt circuits.I need a recommendation for High Voltage probes to measure CRT circuits.One for DMM and one for Analog Oscilloscope.Maybe something in $50 dollar range if possible.

author: PaulAm
author_rank: Frequent Contributor
timestamp: January 10, 2017, 07:00:16 pm
content: If 6KV is good enough, there's a Fluke 80K-6 on ebay for $30 bin right now. There's also one at $47 with a make offer.If you need more than 6Kv, look for a Fluke 80K-40 which is good for 40Kv. Either will work with most DVMsAt least if you're in the US.

author: David Hess
author_rank: Super Contributor
timestamp: January 10, 2017, 08:08:17 pm
content: I have no complaints about the Fluke 80K-6 which I bought off of Ebay for exactly this sort of application. The CRT cathode voltage is relatively low impedance and generally between -2000 and -4000 volts so the 75 megohm input resistance of the inexpensive 80K-6 is not a problem. If you want to read the voltages from other CRT elements, then the 1 gigohm input resistance of the 80K-40 or 80K-15 will be better and of course the higher voltage probe is needed to measure any PDA (post deflection acceleration) voltage but this is seldom necessary. These probes expect a voltmeter with a 10 megohm input resistance for accurate measurements.A high voltage oscilloscope measurement is very rarely needed for CRT work but if you must, then the best options come down to a used Tektronix P6013 or P6015 which include shunt terminations. These probes can also be used with a voltmeter if a 1 megohm termination is present.Beware that new x100 high voltage probes that have a 100 megohm input resistance do not include a shunt termination and cannot be used safely with AC coupling without risking damage to the oscilloscope.
HP/Agilent 6632B OV protection kicking in around 9V - Page 1
Forum section: electronics / repair

author: xtof
author_rank: Newbie
timestamp: January 10, 2017, 09:16:02 am
content: Strange phenomenon in the lab. 2 6632Bs next to each other in the lab, have started to exhibit the same problem at the same time. Below 8V all is well, but above the OV kicks in... If I disable the OV by bridging R351, all is good, voltages are correct when entered up to 20V... any thoughts?brCHristophe

author: AndyC_772
author_rank: Super Contributor
timestamp: January 10, 2017, 10:27:43 am
content: What is the OVP voltage programmed to be? IIRC you can set it from the front panel. It may just be that someone has been fiddling!
Agilent 33250A doesn't boot fully - Page 1
Forum section: electronics / repair

author: khudson
author_rank: Newbie
timestamp: January 02, 2017, 07:36:22 pm
content: Hi folks. I received an Agilent 33250a to attempt repair on. It boots most of the way but gets stuck shortly before I think it should kick over and begin accepting user input. The front panel lights come on, the display reads, "Agilent Technologies 33250A," but gets no further. I think it's at the point where it *should* be testing either the DSP or the waveform memory banks, but it never gets that far.I've done some debugging so far and noticed the following:* the power supply was misaligned and the voltages were out of spec from the service manual (corrected).* Another post mentioned the main SRAM being a potential problem point on these so it was proactively replaced (no change).* All points on the board with oscillator references on the silkscreen have the proper clock on them with the exception of the synthesis FPGA and the waveform RAM.* The main gate array (U302) gets loaded by the configuration IC (U301) and asserts MAR_AWAKE to the CPU.* The main gate array (U302) loads the configuration into the synthesis FPGA (U1201) and it asserts SYN_CONFDONE to the CPU.* The primary PLL (U901) never gets configured by the CPU (I figure this will be done after the CPU is done testing the waveform RAM and it's handed over to the DSP/synthesis FPGA).* The DSP RAM (U507) contents never appear to be loaded (the DSP_RAM_CE line never gets asserted).I have no way of testing the DSP as I don't own a JTAG adapter nor the software to attempt this. I *think* the boot process might be getting stuck here waiting on the DSP to come alive, but I can't figure out how to test it any further. I'd just as soon replace the DSP but the part is obsolete and I can't find it for sale anywhere.The service manual for this AWG is available at:http://cp.literature.agilent.com/litweb/pdf/33250-90011.pdfIn the interest of full disclosure, this is the most complex thing I've attempted to repair thus far and I'm probably a bit beyond my abilities. If anyone has any ideas on where to look next or what I can do to positively identify the DSP being either the problem or alive I'd appreciate it. I really want to get this thing workingThanks!

author: khudson
author_rank: Newbie
timestamp: January 10, 2017, 08:52:55 am
content: I went ahead and reprogrammed the 29F040 ROMs U207 - U210 using the firmware someone posted in another thread in this section. The unit still doesn't get any further than it did before and I still don't have any idea how to test this TMS320 for operation.I will say that the CLKOUT line on that DSP is working, though I'm not sure if that is controlled by the logic core at all.I'm stuck. I need someone's advice who knows what they're doing :/Any help would be appreciated.
Yaesu FT5100 display fault - Page 1
Forum section: electronics / repair

author: christopher iles
author_rank: Regular Contributor
timestamp: January 04, 2017, 07:45:38 am
content: Hello,My FT5100 has developed a display fault. All the bottom segments and all of the bottom left segments of the numerical display have gone blank.All looks ok in the radio i.e. cables, joints etc.Anyone else had this problem and/or know the fix please?The transceiver otherwise works great.Many thanks,Chris.

author: jkf1000
author_rank: Regular Contributor
timestamp: January 07, 2017, 11:55:03 pm
content: Sounds like a connector issue. how is the display connected to the board? has it had a knock or drop? Pictures might help. Karl

author: christopher iles
author_rank: Regular Contributor
timestamp: January 08, 2017, 09:40:42 am
content: Hi and thank you for the reply.The radio had this fault when I bought it; I think the display is connected by a ribbon cable. Don't know if the radio has been dropped; there are no external signs of damage though.I have read that a common fault is the lcd backlights failing and am wondering if the display ribbon has been damaged or dislodged when the bulbs have been changed.Problem for me is my eyes aren't what they used to be and I have trouble seeing the small electronics in newer radios.Regards,Chris.

author: jkf1000
author_rank: Regular Contributor
timestamp: January 10, 2017, 12:19:35 am
content: I understand that they can be quite small and awkward to work with but have you thought about trying to remove and re-fit the ribbon cables. From what I have seen online it looks like a zebra strip connector between the display board and LCD unit, always known to be problematic so certainly worth a look if you have the confidence. Karl
UT804 repair/schematics - Page 1
Forum section: electronics / repair

author: rolkinas
author_rank: Contributor
timestamp: January 09, 2017, 12:35:47 am
content: Hi everyone!Does anyone have schematics of UT804 or UT71D multimeter?Mine ut804 stopped measuring ac voltage. Some time ago it started hanging when touching mains voltage with Com probe. It doesn't matter if meter was powered by mains or batteries.Other measurement seems to work. Still.

author: JFJ
author_rank: Regular Contributor
timestamp: January 09, 2017, 12:50:36 pm
content: The attached pdf file is a schematic for a Voltcraft VC940 multimeter - possibly a re-badged Uni-Trend UT71D?

author: rolkinas
author_rank: Contributor
timestamp: January 09, 2017, 08:12:37 pm
content: Many thanks for schematics!Voltcraft is quite similar to ut804. Fault was in power supply not delivering positive voltage to ES636. Now it works as usual slowly, but works (:
Farnell TSV70 Mk2 restoration  - Page 1
Forum section: electronics / repair

author: reddish75
author_rank: Regular Contributor
timestamp: January 06, 2017, 04:52:41 pm
content: So, Father Christmas brought me two of these with apparent faults as which I've yet to discover, so I thought I'd refer them so I wouldn't have to bother with them in that way for a few years,I thought I'd ask the knowledgeable folk on here what to look for before switching on, best way to switch on (probably for the first time in a few years)?It seems like I'll have questions lots of questions if anyone's willing to help?In the meantime I've wrestled the covers off one and measured the bigger caps which seem to mostly be ok, enjoy some photos of the inside.https://1drv.ms/a/s!AhyV-hIo37nZpy3xFrszVD-3F19XSchematic here,https://1drv.ms/b/s!AhyV-hIo37nZpy-CKAeiXBoBcmDm

author: Messtechniker
author_rank: Frequent Contributor
timestamp: January 07, 2017, 10:09:01 pm
content: No. 1 measure:Before switching on you must unconditionally replace thatcracked input filter/spike suppression capacitor as in pic No. 6.And then look to see if there are any more of this kind whichurgently need to be replaced.No.2 measure:I'd also have a look at all other capacitors.No.3 measure:And also check all metal parts to ensure that they are all connectedvia a low resistance to earth.

author: dmills
author_rank: Super Contributor
timestamp: January 07, 2017, 10:18:30 pm
content: Any time you see that style of class X cap swap it, with those it is not so much a case of if but when.Awful things, and I think there are two more in photo 3.I would suggest that a 60W incandescent light bulb in series with the mains at first switch on is a good idea, makes something very wrong obvious.Good supplies.Regards, Dan.
Hameg HM303-4 Repair - Page 1
Forum section: electronics / repair

author: Ozo
author_rank: Newbie
timestamp: January 06, 2017, 05:46:08 pm
content: I just bought a Hameg HM303-4 oscilloscope online and received it damaged in shipping. First, a component (AD 42830) popped out and was floating around inside. The pins were bent but restorable. I am looking for a replacement but have not seen one so I am thinking a substitute will be required. I need a substitute part number and source or a source for the AD 42830.Second, both Voltage/Div switches are damaged. One is obviously broken right behind the knob. The other has no detent and just spins but does not come out so I can see if it has the same problem. I am thinking I will need new switches. Parts are available at Hameg USA in Maryland but I am concerned that it will be an enormous effort to R/R them. How much trouble is it to do that?Here are remarks re Hameg USA by the seller of the above scope:"A Representative from Rohde & Schwarz promptly contacted me on Monday morning regarding the parts.You should be able to arrange to get the knobs or any other parts by sending and email to: Service.RSA@RSA.Rohde-Schwarz.comRohde & Schwarz USA, Inc.6821 Benjamin Franklin DriveColumbia, MD 21046Toll Free: (888)837-8772 Opt 3Fx: (410)910-7931 "
TA3OM qrp dds vfo help wanted please - Page 1
Forum section: electronics / repair

author: christopher iles
author_rank: Regular Contributor
timestamp: January 06, 2017, 08:56:12 am
content: HelloI have a 0 -10MHz dds vfo which works fine. (made by TA3OM)There are 3 pins on the back of the pcb; vfo out, s meter input, power meter input.Does anyone know what voltages these pins are looking for to work properly.I don't want to experiment really in case I blow the thing up!Thank you,Chris. G0VOE.
PSU with Unconnected Anode Lead - Page 1
Forum section: electronics / repair

author: Dipski
author_rank: Contributor
timestamp: January 11, 2017, 03:19:06 pm
content: Hi folks,I've got an Apple Mac that I'm working on, due to configuration issues I'm not able to connect the Analog Board (w/ PSU), Motherboard and CRT all together. One of the voltages from the PSU is slightly low so I'd like to run it with some load - the only problem being that the motherboard connects to the PSU via. the Analog board (which has the Flyback transformer).Do I risk any damage to the Flyback transformer powering it on disconnected from a CRT?

author: Ian.M
author_rank: Super Contributor
timestamp: January 11, 2017, 04:10:11 pm
content: If the EHT lead arcs to anything you are likely to blow stuff up. The Flyback transformer will probably survive but you risk blowing the line output transistor + any semiconductors on whatever board it arcs to. Don't do it unless you can insulate the lead end to better than 25KV.Also running a line output stage without the scan coils connected is also potentially disastrous.If you've got the analog board schematic, you may be able to run it safely after isolating the supply to the line output stage.
BYX-UU10.5-748 replacement - Page 1
Forum section: electronics / repair

author: disco
author_rank: Newbie
timestamp: January 02, 2017, 08:27:16 pm
content: Hi all,I've fried one side of theBYX-UU10.5-748(L1 on the image below) which looks like a common mode choke and can't find it nor the datasheet anywhere. Does anyone know a suitable replacement part?

author: Daxxin
author_rank: Regular Contributor
timestamp: January 03, 2017, 06:46:17 pm
content: This is the filter of mains stage ac input if burned maybe there is damage on psu board overloadi think you can rewind replacing wire same type count the turns.

author: disco
author_rank: Newbie
timestamp: January 05, 2017, 10:27:30 am
content: Thanks. I'd rather replace it or remove it completely.If this is just a filter then I could theoretically just replace the burned windings with a thick wire at the cost of introducing some noise into the mains?Update a day later:Unsoldered it, soldered two thick wires instead, it's working fine.
Denon AVR-3312 - Page 1
Forum section: electronics / repair

author: SoundTech-LG
author_rank: Frequent Contributor
timestamp: January 06, 2017, 05:23:30 pm
content: Not sure of the odds in play here... did a search on Craigslist for this model, as I have been hoping to find one on the cheap. Immediately found a posting 35 minutes fresh, within 20 miles of here. $20 for this $1100 AVR all accessories included and not a scratch.Well, not sure yet if anything is really wrong with it. The Brit that sold it to me had it on a 220 volt step up (bought overseas). We had some storms and power surges the other day. He says it doesn't work. I don't have a step up yet, but I removed the SMPS board, and all seems well there, but who knows. No shorts on the PA section AFAIK. The drool factor is quite large... more later on what I find, if anything. Amazing Denon info..https://www.hifiengine.com/manual_library/denon/avr-3312.shtml
Bluetooth headphone repair - Page 1
Forum section: electronics / repair

author: dmkmedia
author_rank: Contributor
timestamp: December 27, 2016, 10:23:20 pm
content: i bought a Bluetooth headset for my pc and i had the dongle on the front on my pc facing outwards . i dropped something at the front of my pc and bent the Bluetooth adapter and it has now stopped working.visually there dont seems any broken traces / connectionsany idea where i can startwhen i plug it in windows does noting so its not even seeing im plugging it inthe usb socket is ok as it powers other items

author: KhronX
author_rank: Frequent Contributor
timestamp: December 28, 2016, 02:57:28 am
content: In that case, youDOhave some broken traces

author: WolfmanTech
author_rank: Contributor
timestamp: January 02, 2017, 08:01:42 pm
content: Since windows doesn't see it, I'd guess power or ground have been interrupted, likely by broken solder joints or snapped traces.Alternately both data lines or all four connections could be broken.If I were repairing such damage for my own use, I might use a short piece of usb cable and solder the wires to the next nearest component of each trace, stabilizing/protecting the repair with epoxy once electrical function was confirmed. But that's me and my bodges, you might be able to get away with re-soldering connections and/or bridging the breaks with fin wire. Such tiny fiddly stuff!

author: dmkmedia
author_rank: Contributor
timestamp: January 02, 2017, 10:13:51 pm
content: i tried all that and gave uplast shot to re-flow...and .. nothing..bought another one for £30
need firmware 859XE series - Page 1
Forum section: electronics / repair

author: Daxxin
author_rank: Regular Contributor
timestamp: January 01, 2017, 11:59:53 am
content: U6_rev_C_08592_80075U7_rev_C_08592_80076U23_rev_C_08592_80077U24_rev_C_08592_8007827C512 eprom , if someone has please sharethanks very much

author: bingo600
author_rank: Super Contributor
timestamp: January 01, 2017, 06:20:35 pm
content: Always check @ko4bbhttp://www.ko4bb.com/getsimple/index.php?id=manualsFound it via 859x as search termhttp://www.ko4bb.com/manuals/62.61.142.24/HP_859xE_859xE_series_SA_firmware_EPROM.zip/Bingo

author: Daxxin
author_rank: Regular Contributor
timestamp: January 01, 2017, 06:48:05 pm
content: Thanks for reply Bingo , i found alredy tht but its for 32 pin eprom from 1mb to upunfortunatly my board has 28 pin eprom maximum 512kb

author: Tony_G
author_rank: Super Contributor
timestamp: January 01, 2017, 06:58:17 pm
content: You might also want to try checking out the files are for the HP Yahoo Group:https://groups.yahoo.com/neo/groups/hp_agilent_equipment/infoI did a search on 859 and firmware and a number of posts came up.TonyG

author: azer
author_rank: Regular Contributor
timestamp: January 02, 2017, 06:27:51 pm
content: These are for the 8592A with 512 eeprom.An older version than what you are requesting though.

author: Daxxin
author_rank: Regular Contributor
timestamp: January 02, 2017, 07:19:20 pm
content: Thank you Azer
Philips TV (Fixed) - Page 1
Forum section: electronics / repair

author: DarkZero
author_rank: Regular Contributor
timestamp: December 30, 2016, 09:39:34 pm
content: friend left me 25" philips tv but its broken i approached repairing it since it has some nice features its small but with good specsnow i opened it and saw that supply was fried but i found schematic for iti changed all parts that were dead but im getting some oscillations on the low voltage side checked diodes but really don't know how to check feedback circuiti just feel so stupid not knowing to fix this with this low parts count ... the only thing i didnt use as in schematic is high voltage mosfet i used p10nk80zfpi have to mention that someone gave it a try before me since 400v 100uF cap was missing but the chip was blown some resistors near mosfet so i figured mosfet died as welli attached schematic

author: GasGas
author_rank: Contributor
timestamp: December 31, 2016, 10:28:00 am
content: Please tell your TV model to try to locate the service manual. This is a very basic source, it should not be difficult to repair. Have you downloaded the PWM IC data sheet from the primary side of the source? If the mosfet was faulty, it is 90% chance of the CI PWM having the same destination ...

author: DarkZero
author_rank: Regular Contributor
timestamp: December 31, 2016, 12:22:35 pm
content: i changed pwm chip, mosfet and lots of small resistors aroun the mosfet i used all parts like in schematic i only used different mosfet which is basicly the one that works with 800v instead of 700v ill need to check what model is it, schematic is in the attachment, i measured the output voltage 5vsb jumps between 3-7v and 24v jumps from 13-26v and on the scope its just a mess some weird looking sine wave on top of changing dc voltage

author: GasGas
author_rank: Contributor
timestamp: December 31, 2016, 12:49:59 pm
content: I found the schematic. If the voltages are pulsing at the output, check the IC 902, 903 and ZD903

author: edy
author_rank: Super Contributor
timestamp: January 01, 2017, 06:01:30 am
content: This looks similar to my TV that I repaired a while back. Not sure if it will help, but here is my repair video with schematic and explanation of all the most common parts that fail as per the kit I got. It may help point you to another component that needs replacement. Good luck!

author: DarkZero
author_rank: Regular Contributor
timestamp: January 02, 2017, 12:10:29 pm
content: Quotethx for suggestionsince these components were so cheap i didn't bother to test them so i changed them and indeed it worked, but i wonder why when so many components failed both in high voltage side and low voltage side why it didn't blow the fuse, PWM chip was missing top part and you could see inside mosfet im just glad that with all parts it costed like 7 euros to repair this sothx again i fixed many things around the house using this forum !

author: SeanB
author_rank: Super Contributor
timestamp: January 02, 2017, 09:27:52 pm
content: Semiconductors blow a lot faster than a fuse. they often sacrifice themselves to save the fuse.
Trying to repair an HP10811 - Page 1
Forum section: electronics / repair

author: jpb
author_rank: Super Contributor
timestamp: January 01, 2017, 08:36:50 pm
content: I am in the process of repairing (or attempting to repair) an HP10811-6111 I got on e-bay. It oscillates ok but with a very distorted waveform.I have been using the HP repair manual but have found an inconsistency which unfortunately is in the very area I think my problem lies (AGC circuit).I was wondering if anyone else has delved into these and knows the answer.My question is, what is the voltage Vcc applied to the collector of transistor Q3 (the AGC input).In Figure 8-7 attached it clearly states that it is 5.7V (the same as for Q1 and the rest of the oscillator circuit).On my sample it is 11.8V!But on the standard Voltage table 8.4 show that the collector of Q3 is at 11.8V so my value there is ok.Unfortunately my Emitter of Q3 value (the agc feedback value) is 8V instead of 4.9V which is above the 5.7V supply of the oscillator circuit.Any feedback from anyone with experience will be most welcome.

author: wn1fju
author_rank: Frequent Contributor
timestamp: January 01, 2017, 10:15:07 pm
content: Looks like the actual schematic shows 12V on Q3C and 5.7V on Q3B. Probably just a misprint on the figure you showed.I've repaired a few of these, but my problems have always been in the circuitry involving the oven, not in the actual oscillator. The reason I am posting a reply is to warn you to be VERY careful soldering/desoldering parts. The board material is almost like cardboard and it is easy to burn right through it, taking out traces. I nearly destroyed one of mine.

author: jpb
author_rank: Super Contributor
timestamp: January 01, 2017, 11:10:59 pm
content: Quote from: wn1fju on January 01, 2017, 10:15:07 pmThanks for the warning - I've not yet got to the stage of swapping out parts but will be very careful when I do so.I'm trying to probe components in place and they seem ok (which is frustrating as I was hoping to find an obviously faulty cap that could be replaced).My main issue is I only have a standard (500MHz) oscilloscope probe and I think the capacitance is affecting my readings. The AGC circuit seems to be stuck in an off state which leads to massive oscillator swings but I can't work out if it is the AGC or the tuning of the oscillator.Anyway, thanks again for your post.
Replacing the USB connector of iPhone cable - Page 1
Forum section: electronics / repair

author: LiquidLogik
author_rank: Contributor
timestamp: November 08, 2016, 04:11:02 am
content: Hi,My girlfriend has broken the cable for her iPhone 5. She's some how separated the USB connector in to two pieces.I'm thinking about just cutting off the USB connector and putting on a new one. Are there any hidden electronics or connections in the USB connector?Photos are attached.Thanks

author: Monkeh
author_rank: Super Contributor
timestamp: November 08, 2016, 04:20:59 am
content: No, but.. they don't make a lot of USB plugs for attaching to a cable yourself, and they're likely to be even more fragile than that one.They do seem to make more than they used to, though..Perhapshttp://www.digikey.com/product-detail/en/adafruit-industries-llc/1827/1528-1396-ND/5629444Rather vague on strain relief, to put it mildly..

author: grifftech
author_rank: Frequent Contributor
timestamp: November 08, 2016, 04:39:27 am
content: Solder the wires to a con with a mini / micro usb

author: BMack
author_rank: Regular Contributor
timestamp: November 09, 2016, 06:34:09 am
content: They're $6.https://www.amazon.com/Anker-Premium-Lightning-iPhone-Certified/dp/B00K4VQZCM/Don't waste your time, any fix isn't going to be worth the time and won't last.

author: kripton2035
author_rank: Super Contributor
timestamp: November 09, 2016, 07:25:13 am
content: at $6 I'm pretty sure it's a fake, not apple certified, that is to say it will fail after a system update, when apple wants it to fail...

author: kripton2035
author_rank: Super Contributor
timestamp: November 09, 2016, 07:26:57 am
content: for OP, yes you can soldier any usb plug you may have, the colors are ok inside, green and red for data lines.the certification chip is in the lightning plug.I usually make one working cable out of 2 non-working ones by exchanging the plugs.

author: Monkeh
author_rank: Super Contributor
timestamp: November 09, 2016, 02:43:31 pm
content: Quote from: kripton2035 on November 09, 2016, 07:25:13 amIt's Anker, they're a legitimate brand.

author: LektroiD
author_rank: Frequent Contributor
timestamp: November 09, 2016, 06:00:40 pm
content: I found theseRemaxcables to be extremely robust and reliable. I first found them when I was visiting Thailand, they have since appeared on AliExpress. There are also 2M ones, but not as thick as the one I linked.

author: kripton2035
author_rank: Super Contributor
timestamp: November 09, 2016, 06:42:31 pm
content: Quote from: LektroiD on November 09, 2016, 06:00:40 pmit's (almost) not the problem of being robust, but the problem of being apple certified, so that future system updates will not render the cable useless

author: LektroiD
author_rank: Frequent Contributor
timestamp: November 11, 2016, 12:25:09 am
content: Quote from: kripton2035 on November 09, 2016, 06:42:31 pmNo problems with mine after updating.

author: tooki
author_rank: Super Contributor
timestamp: January 01, 2017, 01:33:14 pm
content: FYI, the AmazonBasics branded Lightning cables are excellent, and are also Mfi-certified.