hybridfree/eevblog-posts huggingface dataset:
precision e200c rf generater - Page 1
Forum section: electronics / repair

author: dartman61
author_rank: Newbie
timestamp: May 21, 2015, 12:14:12 pm
content: Hello, Can anyone tell me how to dismantle this unit, the cord needs replaced. i have all the front screws out. What am I missing?thanks Dartman61

author: Asmyldof
author_rank: Regular Contributor
timestamp: May 21, 2015, 12:30:32 pm
content: I would like to open with the statement your problem description could be somewhat more elaborate.Most of the people answering questions here have super fun jobs they don't like to be away from for too long, so any work you offload on us (such as finding out the actual brand, what it should look like, etc) will makes an answer less likely.I'm still not 100% sure I have the thing right, but I'm guessing there's not that many "e200c" + "rf" devices out there.That said, just typing "e200c rf" into google popped up this link:Does that answer your question? I can't watch it right now, as I only have a few minutes before my simulation ends and I have to do real work again.

author: dartman61
author_rank: Newbie
timestamp: May 23, 2015, 02:37:39 am
content: Hi, Thank you for your input. This was my first time asking a question, however I figured it out. I do not quite get your response meaning, did I do something wrong?

author: Shock
author_rank: Super Contributor
timestamp: May 23, 2015, 02:46:08 am
content: This could have had a live chassis, if the power cable was deliberately cut off of careful you don't kill yourself.

author: GreyWoolfe
author_rank: Unknown
timestamp: May 23, 2015, 02:19:13 pm
content: Quote from: dartman61 on May 23, 2015, 02:37:39 amYou didn't do anything wrong, you just didn't give enough information. When asking advice on how to dismantle a piece of test gear, especially something that may not be a well known name product, pictures are very helpful. A more complete explanation of what you tried is also helpful. What Asmyldorf is trying to say, the more upfront info you give, the more likely a useful response will come your way. Many people here give a quick scan of the posts. If there isn't enough information for them to give a proper response, they aren't going to do research for the answer, they will just move on. Good on ya for figuring it out. Post some pics of the outside and under the hood. Lots of us like seeing that stuff. Shock is on the money, If there aren't bleeder resistors on power supply caps, they can hold a charge for quite a long time and it can be very painful at the very least accidentally shorting yourself out on them. Care should always be taken. Assume there is power unless you have unplugged the chord yourself and assume capacitors have a charge in them unless you properly discharge them.

author: dartman61
author_rank: Newbie
timestamp: May 24, 2015, 12:40:53 am
content: Thank you for your replys. I understand what you mean about more info and pics. Next time I will do better.
triple diffused planar transistor & Epitaxial Transistor, testing bad. - Page 1
Forum section: electronics / repair

author: hyteqsolutions
author_rank: Newbie
timestamp: May 23, 2015, 04:19:43 am
content: Good Afternoon EEVBlog,A tad stuck on this one.B1560 51Y (pnp) Epitaxial Transistor (7 of them)&D2390 51Y (npn) triple diffused planar transistor (7 of them)Used in a Denon AVR-1905 amp.I have tested both transistors the usual way with my auto-range multimeter. Black to middle or Red to middle etc... I get flow as per usual, but when I swap leads and test the outside only with leads reversed again, I get flow, on all of them. I am assuming that this means bad.The Denon unit will fire up (Green LED will blink 5 times, then Red thereafter) the moment the start up cycle hits 'receiver' bang, red LED thereafter. Tested the hell out of this board and replaced some blown caps. Same issue, tested these guys and cannot make headway with them.Datasheet:http://www.slideshare.net/tedyshinoda/data-sheet-power-transistors-sankenThoughts?Thank You,- HyTeQ-Solutions.

author: Shock
author_rank: Super Contributor
timestamp: May 23, 2015, 09:15:22 am
content: On darlingtons there can be a protection diode across the E and C pins, if it shorts the component is faulty and you will see continuity in either direction. If unsure remove the transistor from circuit and perform both a separate diode (if possible) and resistance test and record your results for each test EC CE BE EB BC CB and then it's a little easier to deduce whats happened.Don't expect the base to be the middle pin either, look closely at the data sheet pinout and equivalent circuit so you know exactly which way your testing.

author: wraper
author_rank: Unknown
timestamp: May 23, 2015, 01:33:46 pm
content: Do you measure them in circuit? Also 2SB1560 and 2SD2390 base is a first pin, not in the middle. They are darlingtons too.
Repair and Teardown of an Integrated Hi-Fi Amplifier - Page 1
Forum section: electronics / repair

author: SteveyG
author_rank: Unknown
timestamp: May 18, 2015, 11:49:37 am
content: A video for fault finding fans...

author: Shock
author_rank: Super Contributor
timestamp: May 21, 2015, 01:52:57 pm
content: Begging to be upgraded to a blue LCD.

author: SteveyG
author_rank: Unknown
timestamp: May 22, 2015, 11:47:05 pm
content: Would upgrade to a negative black and white LCD if it was mine, but IMO the LCD and rotary encoder etc. is not required on a stereo integrated amplifier. I've rescued a Cambridge Audio A4 for my work area, so that'll be getting an overhaul and modifications in the coming weeks.
Nas power supply faulty - Page 1
Forum section: electronics / repair

author: Lee-stoke
author_rank: Newbie
timestamp: May 22, 2015, 08:54:53 pm
content: Hi. I only have a basic understanding of electronic but I have had some luck in the past repairing things. More luck than judgement! On inspection my power supply had a couple of bulging caps witch I've replaced but still no joy. Basically the supply is a pc atx power supply. The 5v is good and when you ground the 5v sense the 12v begins to power up then back dead. Any advice on where to start looking to rectify this would be great. It's not a standard form factor so a replacement ain't really a viable option. Many thanks for any possible help.

author: Grapsus
author_rank: Regular Contributor
timestamp: May 22, 2015, 09:28:28 pm
content: Can you post pictures ?

author: Fsck
author_rank: Super Contributor
timestamp: May 22, 2015, 09:29:33 pm
content: Quote from: Grapsus on May 22, 2015, 09:28:28 pmpreferably high quality ones.
Acer Aspire e1-570 backlight needs fixing - Page 1
Forum section: electronics / repair

author: HackedFridgeMagnet
author_rank: Super Contributor
timestamp: May 21, 2015, 07:15:47 am
content: My sons Acer Aspire e1-570 is missing the backlight. 3 months out of warranty.HDMI out is good, screen shows up with a torch shined on it.I took a punt and replaced the screen but the problem is still the same.I am guessing the power supply for the backlight, which I guess is on the motherboard.Has anyone got any info/ schematics, especially the 30 pin connector pinout?the 30 pin connector looks like thishttp://www.amazon.co.uk/ACER-ASPIRE-E1-570-REPLACEMENT-SCREEN/dp/B00K88IBEGAlso could it be some power monitoring setting?

author: Rasz
author_rank: Super Contributor
timestamp: May 21, 2015, 08:05:38 pm
content: Quote from: HackedFridgeMagnet on May 21, 2015, 07:15:47 amhttp://kythuatphancung.vn/uploads/download/9f125_Compal_LA-9535P.pdfbacklight usually doesnt die without a reason, Im guessing liquid damage on the motherboard = eroded connections under lcd connector, backlight fuse or backlight boost converter chip & its passives.You will need to take pcb out. Start by inspecting for moisture signs, pink/red copper pads, grey residue on solder joints, or even missing smd parts. Use magnifying glass/microscope and continuity tester. If you cant find anything then next step is connecting everything outside case and measuring voltages.

author: senso
author_rank: Frequent Contributor
timestamp: May 21, 2015, 08:39:51 pm
content: Check around the lcd connector, I have already repaired many that had a failed mosfet, its easy to spot it, its always a big-ish cooper flood around 2-4 pins of the lcd connector and should have 18-19v when the laptop is connected to the charger.

author: HackedFridgeMagnet
author_rank: Super Contributor
timestamp: May 22, 2015, 12:14:58 am
content: Thanks for the schematic that is great!Liquid on pcb sounds plausible for a kid. Or me for that matter.QuoteOk ok noob mistake.
Help reading PCB layout from service manual - Page 1
Forum section: electronics / repair

author: nixfu
author_rank: Unknown
timestamp: May 20, 2015, 03:34:11 pm
content: Ok. I am not a PCB layout pro, so I don't totally follow the masks etc and the way it looks when you print it out on paper. I assume these are basically just printouts of the gerbers or something from the copper layer maybe.I am trying to repair this thing, and I had to replace a very small g5v-1 relay, and in the process of unsoldering it, and removing it from the board, I noticed what looks like the top pad, and via was still stuck on the leads of two pins when it came out.It was the two pins highlighted in yellow.What I need help with is, do these pins connect to anything on the top, so I need to reconstruct a pad there on the top, when I put the replacement relay in, or can I just solder them on the bottom layer and be ok?What I am asking I guess is, when looking at a PCB layout like this from a service manual from the manufacturer, do the pins with the white circle totally around them, show small pads on top that are not actually connected to anything?That would mean that of these two pins, which are common, only one of them is connected and only on the bottom if I am reading this diagram correctly, so I am ok with not worring about the pads and vias that came off and just making sure I get a good connection soldering the one pad on the bottom.Any advice is appreciated.Thanks!Bonus Q: Does the filled in vs unfilled arrow on the relay contacts in the diagram, denote which is the off/default state?

author: AlfBaz
author_rank: Super Contributor
timestamp: May 20, 2015, 03:46:08 pm
content: Quote from: nixfu on May 20, 2015, 03:34:11 pmIn a word, yes.Quoterelays a normally drawn in their default off state, so it appears they are only using the normally closed contacts

author: Asmyldof
author_rank: Regular Contributor
timestamp: May 20, 2015, 03:54:35 pm
content: Since the yes has already been given...The filled in arrow in the relay contact drawing can sometimes mean a different contact rating, but it is used for different reasons by different engineers at different companies. But mostly just not at all.What often happens is that the contact the spring pulls towards (default on contact) has a slightly higher switching current, because of the contact force. And sometimes one of the two contact is actually better reinforced with harder types of metals, or metals that don't spark, etc.So it CAN mean that. But it might not.
Oven Simmerstat Questions, Help needed.  - Page 1
Forum section: electronics / repair

author: peps1
author_rank: Regular Contributor
timestamp: May 19, 2015, 07:23:36 pm
content: Hello Guys,I got a Magnetic Stirrer Hotplate from ebay with a broken temperature control going so cheap I thought it would be worth a punt.Got it on the bench today and tested it out, as described, everything works apart from the temperature control, the plate heats up but cant be adjusted, and the control pot just keep turning and turning.I stripped it down, and assume the problem is the Simmerstat (something I have never worked with before).The Part is a Diamond H Controls LTD 31ER1TF 45, with tabs forLine,Load A,Neut, andPilot,Load B(not connected)I googled he part number and found a this:http://www.amazon.co.uk/UNIVERSAL-REGULATOR-SIMMERSTAT-COOKERS-APPLICATIONS/dp/B00J5JOX64That states it replaces Diamond H 31ER1TFShould I order this one, or am I missing something important here?

author: Gyro
author_rank: Super Contributor
timestamp: May 19, 2015, 07:57:07 pm
content: So long as the physical dimensions are ok (shown in answer to a customer question) then I think you should be fine.There's nothing particularly complex about a Simmerstat, it's a simple thermo-mechanical device. Inside there's a heating element wrapped round a bi-metal strip to simulate what the main element is doing. The strip opens the switching contact as it is heated, breaking the circuit and closing again as it cools. The knob simply changes the position of the 'fixed' contact so that more or less heating of the is needed to open the contacts again. Think of it as a very slow mechanical pwm. If the knob just keeps turning then it sounds like a mechanical failure, or possibly failed internal heater.As long as you can identify and map the connections across to the new simmerstat correctly then you shouldn't have any problem.

author: peps1
author_rank: Regular Contributor
timestamp: May 19, 2015, 09:35:53 pm
content: Thank so much Gyro.Very good of you to take the time to explain a simmerstat

author: Gyro
author_rank: Super Contributor
timestamp: May 20, 2015, 09:28:31 am
content: My Pleasure
7" screen repair? - Page 1
Forum section: electronics / repair

author: warmbloed
author_rank: Newbie
timestamp: May 16, 2015, 07:53:28 pm
content: Hello everybody,I have an old 7" lcd screen that I want to put to some use with a raspberry pi, unfortunately, I can't find any type of documentation so I opened it up in the hopes of being able to find the pinout. I think I have found the connections for power but I am unsure. There are a few bridge wires of which I don't know if the previous owner or the chinese kids put them in. What would be the best way of finding these power connections? I was hoping that once I found those I could take analog video and audio outputs to search for the AV connections.It's a Zanon MTP-769 using a SHARP display and I cam almost certain it needs a 12V intputI thank you all!EDIT: Apparently the image link broke, I have now hosted my image elsewhere, Without Rasz's post I may never have spotted this, thank you, also I have found that the 05DZ11 was outputting 0.3V so I have since attatched the 5V rail directly to it's output pad(updated picture above), still won't turn on though.

author: Rasz
author_rank: Super Contributor
timestamp: May 18, 2015, 07:39:52 am
content: you can start by buying yourself a camera

author: warmbloed
author_rank: Newbie
timestamp: May 19, 2015, 10:45:32 am
content: Thank you for your reply, otherwise I may not have noticed that the link had broken.

author: Rasz
author_rank: Super Contributor
timestamp: May 19, 2015, 11:45:59 am
content: http://circuits.datasheetdir.com/45/TL1451A-EP-circuits.jpgyou could start with pin 9 of that, maybe 12v, maybe less. its dual channel so my guess is you only powered half the stuff with that 5vwhats the chip with nsp7something sticker? and the sharp in left upper corner, one of them will have datasheet with RGB/AV pinoutps: is there a connection between pad with red wire and pin 3 of the chip you took off?
Philips/Fluke PM95 - Page 1
Forum section: electronics / repair

author: nickolo
author_rank: Newbie
timestamp: May 17, 2015, 07:56:50 pm
content: Hello everybody !I´m new here at the forum but i have followed the youtubechannel for several years.I am good at repairs of all kind of electronics but now i seem to have moved into the dark.I have got a Philips/Fluke PM95 scope/meter with a display that won´t come on.It draws about 300 mA when i push on but the display does not react at all.Anybody with similar experience ?RegardsNicklas (nickolo)

author: Fraser
author_rank: Super Contributor
timestamp: May 17, 2015, 08:22:29 pm
content: I've got the schematics somewhere. I will find them for you.Aurora

author: Fraser
author_rank: Super Contributor
timestamp: May 17, 2015, 08:25:55 pm
content: Service manual is here:http://bee.mif.pg.gda.pl/ciasteczkowypotwor/Philips/pm93_95_97_fluke_93_95_97.pdfMay help you diagnose the faultAurora
Led Pool light  - Page 1
Forum section: electronics / repair

author: Nick_Balog
author_rank: Newbie
timestamp: May 18, 2015, 03:02:31 am
content: Anyone ever troubleshoot a flickering jandy watercolors pool light?

author: Nick_Balog
author_rank: Newbie
timestamp: May 24, 2015, 07:04:57 pm
content: Ok.... For anyone looking at this, I think I made some progress. I ruled out the thermal shutdown and solved a grounding issue,however my LEDs are still dim. Can anyone point me to a good tutorial or explanation on how a 110 source gets stepped down to work with LEDs (I'm guessing it's being converted to 12vdc at some point but I'm lost without schematics)

author: kolbep
author_rank: Frequent Contributor
timestamp: May 24, 2015, 07:26:52 pm
content: For safety,pool lights are almost always 12v. It is illegal (in South Africa) to install one in a pool, if the Voltage it operates on is more than that.Normally there is a transformer in the Pool DB or Box, that steps the voltage down from Mains to 12vAC. Then the 12v goes to the pool fitting, that (might have) a Bridge Rectifier or Diodes to convert from AC to DC...

author: Nick_Balog
author_rank: Newbie
timestamp: May 31, 2015, 02:23:09 pm
content: Well, I was poking around and decided that I would replace some caps in question and these two units, although I don't quite know how to identify them nor their function on the board. The Caps are 50v if that gives you an idea. One sorta looks like it has a slight bow so it could have gone bad but it's really too slight to say it's shot by observing. I touched the top of it and got a slight jolt. In all my years of doing arcade boards I never had that happen, but that's at the 5volt level.
Repairing Component Tester Module on Hameg 205-3 - Page 1
Forum section: electronics / repair

author: valegrete
author_rank: Newbie
timestamp: May 16, 2015, 12:54:51 am
content: Good evening, ladies and gents!A few questions here,I recently acquired a Hameg 205-3 CRO on eBay for pretty cheap, and I've been having a few quirky issues with it (the first few days of using it, any time the trace went past the second lines above and below horizontal zero, it would reflect back down in the opposite direction. This issue appears to have went away so I'm considering it self-corrected for now). There are two remaining physical issues with the scope that I want to rectify:1. The plastic shaft coupling for the time/div vernier is split, making it impossible to adjust the pot. I can't find any suitable replacements online so I'm thinking about trying to use heat-shrink tubing as a way to couple the vernier rod and potentiometer shaft. Anyone else have any other jury-rigging ideas for this issue?2. The component tester doesn't work at all, so I pulled the case off and found the associated fuse, which I determined to be faulty after a quick multimeter test. At first I was pretty happy at what I figured would be a quick fix, but I'm growing discouraged because I can't find a fuse with the right amperage rating. The manual says it should only be replaced with a 50 mA rated fuse (see below), but I can't find anything under 250 mA. I know going with a higher amperage defeats the purpose of the fuse, but I wanted to ask people with more experience than I, if I never do something as silly as hooking up the component tester to a live circuit, would a 250 mA fuse be fine just to get me running?Thanks in advance!PS: The exact fuse specification is a "5 x 20 mm, quick-acting, 250 V, C, 50 mA (IEC 127/II or DIN 41661)"

author: tautech
author_rank: Super Contributor
timestamp: May 16, 2015, 02:27:46 am
content: Welcome to the forum.If you can't find a fuse, you might be able to adapt a SMD fuse to fit.Superglue to old fuse and add thin external wires soldered to SMD fuse and to old fuse end caps.

author: Shock
author_rank: Super Contributor
timestamp: May 16, 2015, 06:47:01 am
content: Try also searching and subbing words e.g. "fast" instead of "quick" and "0.050a" instead of "50ma" and add the words "fuse" and "IEC 127/II" or 'DIN 41661" in google then if you find brands you can use the part numbers to find them on vendors websites.http://uk.farnell.com/fuses_cartridge/fuse-current/50ma/pg/110131950

author: valegrete
author_rank: Newbie
timestamp: May 16, 2015, 09:05:26 pm
content: Thank you, guys! I actually feel pretty silly on this one after reading your responses and trying a few more combinations of keywords. Found exactly what I needed from Mauser.I went ahead and got some rubber cement and heat shrink tubing to repair the broken vernier as well. I will report back as soon as everything is done. Hopefully this corrects everything.

author: tautech
author_rank: Super Contributor
timestamp: May 16, 2015, 09:10:51 pm
content: Quote from: valegrete on May 16, 2015, 09:05:26 pmNo problem, we were all newbies once.
HP 6200b - Page 1
Forum section: electronics / repair

author: kolonelkadat
author_rank: Regular Contributor
timestamp: May 15, 2015, 10:59:55 pm
content: I recently got a 6200b that has some issues. Chief among them is the burned out diode cr34. According to the schematic, it is a RCA 1n3253 rectifier, silver, 500mA, 200PRV.The datasheet for the 1n3253 gives specs I0=.75 amps Vf=1.2v and Ir=5uAmps@PIRI cant seem to find an exact match at mouser and I'm not sure which spec is most important for this particular diode. My gut says that as long as PRV>=200 and I0>=750mA then it should be okay, but gut's a damn moron. If anyone could have a look at the schematic and let me know, Id appreciate it.Also if you have any insight as to what may have caused the problem in the first place, I'd love to hear it.schematic is here:http://www.hparchive.com/Manuals/HP-6200B-Scheamtics.pdf

author: Andy Watson
author_rank: Super Contributor
timestamp: May 15, 2015, 11:19:02 pm
content: CR34 is not critical. Its function is to protect the supply against reverse polarity from the terminals. I would substitute a 1N400x series diode.

author: kolonelkadat
author_rank: Regular Contributor
timestamp: May 16, 2015, 01:02:05 am
content: sounds good man. Thanks for the help.

author: Paul Moir
author_rank: Frequent Contributor
timestamp: May 16, 2015, 05:13:08 am
content: My 6294A would go negative when the current control was turned down all the way. I was planning on changing that diode to a schottky so it would only go to -.3v instead of -.5v. I went in another direction in the end. No big deal though.
90V out on a protek 6003L bench power supply - Page 1
Forum section: electronics / repair

author: matt6ft9
author_rank: Contributor
timestamp: April 30, 2015, 06:05:26 pm
content: A Protek 6003L is a single adjustable output, 0-60V, 0-3A bench power supply. It also has a 5V fixed output. When I received it, it would power on, but the Vout was in the 80-90V range! The voltage set knobs don’t seem to effect the output voltage.After taking the case off, it was obvious the 4700uF, 160V cap had failed. (see the photo of the label peeled off, the top of the cap was also domed) It is interesting to see the main transformer appears to be a toroid. The fan in the back of the unit was also seized. So, a new 4700uF cap and DC fan was installed.Powering unit back up after the repair, the DC output was still in the 90V range. The voltage on the 4700uF, 160V cap is 101.6V. The front panel reads 79.6V and the terminals on the front read 101V) While powered off, I measured the bridge rectifier with multimeter on the diode setting, the bridge rectifier seems good. Without a schematic, it’s hard to tell what to look at next.

author: SeanB
author_rank: Super Contributor
timestamp: April 30, 2015, 07:16:44 pm
content: Pull out that heatsink and you will find that the power devices on there are either very leaky or shorted. You do not really need a circuit diagram for a simple power supply.

author: Kleinstein
author_rank: Super Contributor
timestamp: April 30, 2015, 07:17:50 pm
content: Having the full voltage at the output very much indicates blown power transistors (or whatever power device is used). There may be other parts (driver transistors) blown as well.60 V and up to 3 A sounds like a lot of power - so there should be way more than just one power device. If there are relays for switching between transformer tabs, these can be also blown (at least don't test at high current before they are checked). A stuck relay may cause the output stage to overheat under load.

author: matt6ft9
author_rank: Contributor
timestamp: April 30, 2015, 08:04:37 pm
content: Good call! I removed the heatsink, there are two, Toshiba 2SC5200 attached. (NPN, 250V, 17A, 150 watts) The one on the left in the picture appears to have nearly shorted leads. (less than 12 ohms) The insulation on one of the wires is cracked, it looks like it might have become too hot. I’ll have to put a couple of 2SC5200’s on my next order.

author: matt6ft9
author_rank: Contributor
timestamp: May 14, 2015, 07:04:38 pm
content: Update:The 2SC5200's (mouser part number 512-2SC52000TU) arrived.The transistors were installed and the power supply is now operational.Thanks for the help.Matt
Pls help me repair HP 54642A OSC - Page 1
Forum section: electronics / repair

author: chihaxinh
author_rank: Regular Contributor
timestamp: May 12, 2015, 03:31:45 pm
content: Hi, Everyone!I have one HP 54642A OSC - and i have a big trouble when i measurement frequency., pls see table belowSign Gen - HP 55642A measurement100 HZ - 150 Hz1KHz - 1.5 KHZ100KHZ - 150 KHZ1 MHZ - 1,5 MHZI have error about Measurement Frequency = Real frequency * 1,5OSC have 2 type input impedance - 50R and 1Meg ! I think hybird atten have trouble , other function it's OK ( RMS , Peak - Peak ..etc mearsurement option )Below it's picture about carlib information ( Fail in high frequency )Pls help me repair OSC ! Sory for my english , i speaking english not well !Best regards !Nam Nguyen Hai

author: Smith
author_rank: Frequent Contributor
timestamp: May 14, 2015, 09:04:19 am
content: Both devices probably have oscilator in and outputs. You could connect the signal gen oscillator out to the osciloscope oscilator input or the other way around. Measurements should be spot on. This eliminates any possible oscillator trouble.I assume both oscillators to be 10MHz.BTW does the selftest show any errors?

author: chihaxinh
author_rank: Regular Contributor
timestamp: May 14, 2015, 04:40:27 pm
content: Dear SmithI runing seft test OK , you can see picture. Wave form it's signal from triger output .When i runing User Carlib , i see function allway return to menu ( not running ), you can see video in link below.http://www.4shared.com/video/ipt3Jolvba/video-1431620725.htmlPls help me fix OSCThank you so much !Best regardsNam Nguyen Hai
Anyone out here that has a service manual for a Samsung LE32B355F1W - Page 1
Forum section: electronics / repair

author: Hagis2k
author_rank: Regular Contributor
timestamp: May 07, 2015, 08:09:33 pm
content: I am trying to repair a broken lcd tv set (Samsung LE32B355f1w) and i am trying to obtain a service manual for this device without paying $25 for it just a schematicover the power supply would be enough.Q1820 and Q1821 and NT811S (thermistor i do believe) are toastAs far as i can tell these transistors drive the ccfl on the device

author: kloetpatra
author_rank: Regular Contributor
timestamp: May 13, 2015, 05:57:30 pm
content: look for a board designator! you're most likely to find at least a similar board on elektrotanya.com
Agilent 33120A - 603, 604, 606, 608 error codes - Page 1
Forum section: electronics / repair

author: mercoz
author_rank: Newbie
timestamp: May 11, 2015, 07:20:26 pm
content: I bought an Agilent 33120A 15 MHz Function / Arbitrary Waveform Generator off ebay that was a for parts, not working unit, to see if I could fix it. It displays a 603, 604, 606, 608 error codes. I have poked around a bit, but I'm drawing a blank. The voltages seem to be ok. Any other ideas on what I should look at?Nathan

author: dacman
author_rank: Frequent Contributor
timestamp: May 12, 2015, 12:56:42 am
content: Check the major filter capacitors (mainly the aluminum electrolytics). From the service manual, the error codes point at two RAM circuits (U404 and U405 for error 603, U205 for the other errors).
Fuse substitution in a LCD TV - Page 1
Forum section: electronics / repair

author: Stonent
author_rank: Super Contributor
timestamp: May 14, 2015, 02:29:44 am
content: I picked up a 19" 720p TV at a charity store for $10 (SuperSonic SC-1911) . The lady said she didn't think it worked because someone tested it with "this" (she holds up a Linksys router power supply) and it didn't come on.I looked at the back of the TV and it said 12V 35W Max and the power supply for the Linksys router was 12V ad 350mA. I told her my main concern was I couldn't tell if there were scratches or cracks on the LCD.She said I could return it for store credit if it didn't work. I took it home and as luck would have it, I had not one but two 12V power supplies with the right polarity, right sized barrel connector, and just enough wattage rating.It was DOA so I opened it and started testing voltages and got the the point where there was voltage on one side of a fuse and not the other. I shorted it out with some alligator clips and it powered up. The fuse was 250V 5A or 2.5A (I can't remember which) which seemed a bit high for a TV that draws up to 35W at 12V. One spot that I thought was the black goo from the LCD being cracked ended up being some black marker on the screen and some vigorous rubbing with 95% IPA and some finger nail scratching got most of it off.The fuse was a slow blow axial lead glass fuse and I was wondering what the harm would be in bodging in a 12V 5A or 12V 3A automotive fuse instead? I have a small supply of automotive glass fuses.Again, the TV itself runs off of 12V and the panel is LED lit, so there shouldn't be any high voltages inside to worry about, so I assume the high voltage rating was just for transient voltage suppression? If anything I would assume the lower voltage fuse would just be more likely to pop and I would assume not any less safe since it wasn't an HRC type.I haven't been able to find any repair manuals on the TV, but when I searched for the part number of the main board I found a dozen or so identical TVs under various brands, some well known like Westinghouse, but others were equally as obscure as "SuperSonic" The manuals all appeared identical except for the front and back pages that had the logos and contact numbers.It appears to be a current product still as wellhttp://104.171.7.220/index.php?route=product/product&path=67_68&product_id=83What do you think?

author: Richard Crowley
author_rank: Super Contributor
timestamp: May 14, 2015, 02:40:29 am
content: Quote from: Stonent on May 14, 2015, 02:29:44 amWell, 35W @ 12V = 2.9A according to Ohm's LawOf course, you could actually MEASURE the power supply current.
Laser diode & LED - what's going on here? - Page 1
Forum section: electronics / repair

author: SL4P
author_rank: Super Contributor
timestamp: May 10, 2015, 11:19:42 am
content: I've been asked to repair a handheld laser diode 'probe' with a status LED included.The original had been mangled - and basically all old connections were physically ripped apart (under epoxy & hot glue!)The attached drawing is what I 'think' the original wiring was set up as, but it doesn't work.Interestingly - the unit's controller also shows a strange symptom...If the pushbutton is pressed (to start the timed cycle), and there is no LED or laser diode in circuit - the controller displays 000... If the diodes are in circuit (paralleled across the 2V line) the controller shows a different value*... so I guess it's displaying some error or status measuring the current draw ??Any ideas what the circuit is likely to have been?It was a real dog's breakfast - apart from being totally trashed internally!(* the values displayed are even more confusing -- I have four completely separate controllers, and three of them show different numeric values when the LEDs are in circuit!)-- and sadly, no manual or schematics ofanysort. Just an (old) micro on each controller board.

author: Kleinstein
author_rank: Super Contributor
timestamp: May 10, 2015, 03:11:00 pm
content: A white LED needs something like 3 V to work. A normal NIR laser (e.g. 780 nm) will need at least 1.6 V (more likely 1.8-2 V). So 2 V will not work. Also 3 V at the 35 ohms resistor would mean something like 100 mA for the laser diode before the LED turns on - that's quite a lot.It is hard to say how the parts should be connected. An alternative circuit would be the 35 Ohms in series with the laser diode and the whole thing parallel to the white LED.What wavelength and power is the laser supposed to be ?

author: SL4P
author_rank: Super Contributor
timestamp: May 10, 2015, 04:27:20 pm
content: Zero documentation but apparently the laser is 50mw @ 830nmI'll have it specked when it 'works'.BTW with the laser and LED in parallel straight across the 2V drive - both are illuminating - just that odd controller display issue!!?Sadly the controllers are soldered to rear facing connectors which are pre-mounted through the front panel - sigh.
Repair of an Agilent 54845A - Page 1
Forum section: electronics / repair

author: Jwalling
author_rank: Unknown
timestamp: May 17, 2015, 09:55:59 am
content: Came across this on Yahoo's HP/Agilent group.http://www.dasarodesigns.com/projects/fixing-an-hp-agilent-54845a-infinium-oscilloscope/I guess perseverance pays off!Jay

author: VK5RC
author_rank: Unknown
timestamp: May 18, 2015, 06:57:23 am
content: Isn't Dave's motto of repair "thou shalt first check electros and power supply rails".I have been lead a similar 'merry dance by before believing fault codes!
OBY-600 Moving Head Luminaire - Need Control Board - Page 1
Forum section: electronics / repair

author: kolbep
author_rank: Frequent Contributor
timestamp: May 09, 2015, 09:04:03 pm
content: Some time ago I was trying to fix a problem with a OBY-600 Moving Head DMX Controlled Luminaire,UnfortunatelyI had a probe slip, which put 12v onto the 2 Pic Microcontrollers on the main Control Board (the one with the LED Displays and Buttons) The Micros are PIC16C57C's.I was told that since everybody is moving over to LED fittings, that this one is discontinued, and even if I get it working, I will only be able to sell it for about USD200 (and this is a 40KG beast, so shipping will also lower the cost!). So I would rather just get it working again, and use it.If it was a simpler design, I might have been able to produce code for the 2 pics, but as it is, it is very complicated.1 Controller handles the 7 Seg DisplayThe other controller receives the DMX and then spits out commands onto a common bus between it, and the (at least) 12 other PICs. Each of those pics controls a seperate stepper driver chip.So I do not know the protocol on the bus between the main uC and the rest of them (and as that main chip is fried, I have no way to try reverse-engineer the protocol)Does anybody have a dead one lying around that they will be willing to part with the control board (or even just the PICS) I will gladly pay postage to South Africa.The other option is to try and sell it as non-working, or even part it out. But I don't think it will fetch much in either case (although it has quite a few stepper motors, decent optics, working lamp,etc)...But If possible, I would really like to resurrect it.ThanksP
repair help needed on tek tds 680b, same psu as 520b - Page 1
Forum section: electronics / repair

author: Arjan Emm
author_rank: Regular Contributor
timestamp: May 09, 2015, 03:57:52 pm
content: I bought a cheap 150 euro tektroniks tds 680b not long ago. I bought it in not working condition but it turned out to be in calibration mode. I flipped the switch inside and it worked. All self tests checked positive.After a week on standby i woke up in the morning and found that the gfi of my house installation tripped, 20 mA, no fuses just the gfi. Flipped it back on and no problems, everything in the house worked except the tek, appears to be completely dead.I measured the voltages on J27/6 and J26/5, nothing at all.The main cap on A17 charges too 325V as it should. The scoop draws about 100 mA when turned on by the main switch. The standby on off switch doesn't do a thing. the push button on the A11 mainboard and shorting pin 3&5 on jumper J26/5 also don't start up the psu. 0V on all output voltages.I followed the trouble shouting table in the TDS 520B, 540B, 620B, TDS 644B, TDS 680B,TDS 684B, TDS 724A, TDS 744A, & TDS 784A service manual. and it comes down to replacing the psu.And i looked at the TDS 520B Mod CM Digitizing Oscilloscope Component Service Manual. It has a complete schematic of the psu.I in circuit measured the main switchers and they the appear allright, hence the fuse stays in.But i'm at a loss now. No popped parts, just dead. Any ideas anyone?

author: SaabFAN
author_rank: Frequent Contributor
timestamp: May 09, 2015, 06:24:16 pm
content: I just read an article on a website where someone described how he revived a TDS 524A. He spoke about a Transistor that is responsible for the standby-power that blew up.Link to his website:http://jvgavila.com/tds524a.htmMaybe that's a start?

author: Arjan Emm
author_rank: Regular Contributor
timestamp: May 09, 2015, 07:22:16 pm
content: Thanks, i saw that link before. It seems a slightly different supply. My psu does have a tap on the cooling element for that falty bu508. But no option on the pcb to install it.
pioneer vsx 922 no power - Page 1
Forum section: electronics / repair

author: choksi
author_rank: Newbie
timestamp: May 08, 2015, 09:05:06 am
content: hi every bodypl help me to solve this problem

author: BradC
author_rank: Super Contributor
timestamp: May 08, 2015, 09:48:32 am
content: What problem? I don't see any problem from here.

author: choksi
author_rank: Newbie
timestamp: May 08, 2015, 05:07:19 pm
content: Pioneer vsx 922 cannot power on

author: David_AVD
author_rank: Super Contributor
timestamp: May 08, 2015, 10:36:59 pm
content: Oh come on guys, just tell the poor guy what component to replace. Mate, nobody is going to help you with a request like this. Get off your arse, do some initial investigation and come back with what you've found.

author: mathsquid
author_rank: Frequent Contributor
timestamp: May 09, 2015, 12:15:27 pm
content: Wild guess (based on anecdotal experience): It's the thermal fuse inside the main transformer in the power supply.

author: Flump
author_rank: Frequent Contributor
timestamp: May 09, 2015, 07:00:12 pm
content: Quote from: choksi on May 08, 2015, 05:07:19 pmdid you plug it in ?
Standard Amplitude Signals  - Page 1
Forum section: electronics / repair

author: mskobier
author_rank: Regular Contributor
timestamp: May 06, 2015, 01:56:29 am
content: All,I'm to the point that I need to do a limited calibration to set the preamp gain (CAL 02) on one of the 2465s I have been working on. In reading through the calibration instructions in the manual, in Table 5-4, Vertical Calibration Signals, it specifies a number of Standard-Amplitude signals to apply. Since I do not have access to a PG-506 Calibration Generator, I am left with coming up with an alternate method of generating these voltages. What I need to know is exactly what is a Standard- Amplitude Signal? I am assuming it is a sine or square wave, but at what frequency? Once I figure out what wave form and frequency, I'm sure I can come up with a method to generate these voltages. Can someone educate me on what form and frequency signal I need to generate?ThanksMitch

author: Shock
author_rank: Super Contributor
timestamp: May 06, 2015, 02:52:46 am
content: Just a guess but an online search of the PG-506 Calibration Generator manual should answer that.

author: SoundTech-LG
author_rank: Frequent Contributor
timestamp: May 08, 2015, 08:49:50 pm
content: The main PG506 output is a square wave, terminated to a 50 ohm load @ 1kHz, adjustable through it's step attenuator in the typical 5, 2, 1 output level steps.
Juwel aquarium integrated lights - Page 1
Forum section: electronics / repair

author: akis
author_rank: Frequent Contributor
timestamp: May 11, 2015, 10:26:26 pm
content: Has anyone got a Juwel aquarium that comes with lights like this:http://www.amazon.co.uk/Juwel-High-Lite-Light-Unit-120cm/dp/B003ZG8YXG/ref=sr_1_4?s=pet-supplies&ie=UTF8&qid=1431382972&sr=1-4&keywords=juwel+lightingI have looked on second hand Juwel Rio aquariums and so many come without the lighting unit because it seems they break so often.I have bought two Juwel tanks and both units did not work. One is in pristine condition, no signs of damage, no water in the tube holders, it looks positively new. Yet it is broken. I did try to prise open the other one, but it is sealed/welded shut. You'd need to cut through 100cms length of plastic to get to the insides I think.Has anyone got experience with these units and have you tried to repair them?
Keithley 2000 Firmware compatibility - Page 1
Forum section: electronics / repair

author: ElektroQuark
author_rank: Unknown
timestamp: May 07, 2015, 06:08:33 am
content: There are some PCB versions, with different MCUs ans ADC, of the K2000 main PCB.Are all firmware versions compatible with all board revisions?

author: Smith
author_rank: Frequent Contributor
timestamp: May 07, 2015, 07:29:43 am
content: Yes all FW's are compatible as far as I know. I should mention FW A20 needs recalibration after flashing, this is the newest version.http://doc.xdevs.com/article/keithley-instruments/#2000

author: ElektroQuark
author_rank: Unknown
timestamp: May 07, 2015, 12:49:55 pm
content: Only de A20 version needs recalibration?Some revisions of the PCBs use different MCUs. Do you now if they are interchangeable?

author: Smith
author_rank: Frequent Contributor
timestamp: May 07, 2015, 02:29:23 pm
content: Yes I have heard from multiple people they had to recalibrate after flashing to A20. As I remember correctly it has an exta calibration step.I have never heard of anyone who had problems with any upgrade. One of our oldest keithleys has an official upgrade to A15.
1970s RCA TRIACs - Page 1
Forum section: electronics / repair

author: BurningTantalum
author_rank: Frequent Contributor
timestamp: May 06, 2015, 06:45:01 am
content: Yesterday I spent a happy hour digging the hard silicone potting compound out of a Mercury outboard CDI unit. The main switching device appeared to be a triac of RCA manufacture dated 1978. It had failed completely all ways round, possibly due to the external rubber covered wires having lost their rubber or my non-electronic friend's attempts to 'test it' with a 12v car battery.I replaced the triac with a general 400V TO220 and the unit works fine when linked up to my test rig - a 1980 Johnson 15hp.Suitably encouraged I have dug into a second different unit and found two RCA triacs of a similar type. The first triac is RCA 66375 and the second pair are RCA 66133. They are TO8 cases; like a big TO5.Purely out of interest- does anyone have any info on these devices? I can find nothing on the net, a 1960s catalogue does not list them.

author: smjcuk
author_rank: Frequent Contributor
timestamp: May 06, 2015, 07:28:35 am
content: RCA are a pain. They seem to have had a crisis of half bothering with JEDEC numbering and then not bothering and then bothering again. I've got a bunch of RCA power transistors here that aren't in an RCA catalogue, don't have JEDEC numbers but do have a 6 digit RCA part. I'm wondering if they provided specialist one offs to some companies. Fortunately a random guessing and finger crossing picked that 2n3055 worked as a substitute for mine!

author: oldway
author_rank: Super Contributor
timestamp: May 06, 2015, 10:34:14 am
content: I have never seen a CDI unit using a triac...always a SCR (thyristor).Are sure it is a triac ?

author: BurningTantalum
author_rank: Frequent Contributor
timestamp: May 07, 2015, 02:13:22 am
content: Thanks both of you.The units are both for twin cylinder motors but are slightly different in design.Of course the second unit with two switching devices are thyristors, I posted without thinking ! In effect there are to separate circuits, as in the old OMC units.This is now repaired and running.The first unit is definitely a triac- I replaced it with one and the unit works fine. There are two 1.5uF caps that charge opposite polarities from the magneto coil via suitable diodes; the triac is triggered and the relevant cap discharges via the associated coil- one cap one way through the triac and the other cap the other way through the triac. I have not seen this before, but don't make a habit of trowelling out the potting compound from these units ! Just a favour for a friend.BT
Help with locating replacement binding posts? - Page 1
Forum section: electronics / repair

author: rigrunner
author_rank: Frequent Contributor
timestamp: May 06, 2015, 04:04:45 pm
content: I need to replace a pair of front binding posts in a Topward 6603 PSU.The originals are very long and i've not found a suitable replacement yet. Anyone know who makes these and where to buy replacements?Topward will sell me a pair but they have a transaction charge for orders under $5,000 that kind of makes the purchase silly.

author: mskobier
author_rank: Regular Contributor
timestamp: May 06, 2015, 08:03:05 pm
content: If it were me, I would get some brass rod the diameter of the mid section of the stud, cut to length, ,then thread them to the same diameter, pitch, and length as the originals. Thread a nut down to the bottom of the shorter threaded section, and solder in place from the inside. You can make the reduced size portion on the end by chucking in a drill press and while spinning, use a hand file to reduce the diameter. You can also reduce the diameter of the soldered on nut the same way. Factory is better, but the home made path works well too. Drilling the cross hole is easy in a drill press too.Mitch

author: rigrunner
author_rank: Frequent Contributor
timestamp: May 06, 2015, 10:25:05 pm
content: I'm hoping that someone reading will know who makes these, but making something to fit is certainly an option.It maybe the only option if no one knows who the manufacturer is.
Does the Yamaha RX-V1000 have a diagnostics mode? - Page 1
Forum section: electronics / repair

author: Gringo
author_rank: Newbie
timestamp: May 05, 2015, 09:29:41 pm
content: Hey guys! I scored an RX-V1000 from a local thrift store knowing it was not functioning. Before I open her up, I wanted to know if it has a diagnostic mode like I hear so much about with other models. At the moment, when I push the power button, all I hear is the relay clicking on and then back off after a couple of seconds. There is no display of any kind. Would a diagnostic screen come up regardless (that is, if it has one)?Thank you!

author: Gringo
author_rank: Newbie
timestamp: May 06, 2015, 03:09:20 pm
content: Nevermind guys. I was PM'ed with the service manual. It indeed has a diag mode. It also has two 22 picofarad caps. Hopefully it will just be a simple fix with either one of those being bad.
TDS644A problem with new nvram chip - Page 1
Forum section: electronics / repair

author: Daxxin
author_rank: Regular Contributor
timestamp: May 08, 2015, 09:45:57 am
content: Replaced DS1650Y chip with new one after reprogrammed with old content here in attachment but look corrupted or scrambledi still get error at boot and switching the menu tryng to selecting CAL i get block error.