hybridfree/eevblog-posts huggingface dataset:
Vintage fan doesn't play nice with electronics - Page 1
Forum section: electronics / repair

author: Drewboy
author_rank: Contributor
timestamp: February 13, 2015, 01:44:27 am
content: I have recently been given a charming old oscillating desktop fan, pictures attached.It still works nicely however I noticed that the instant I turned it off it triggered the surge protection shut down on the wireless router that was plugged in adjacent to it. Flyback spike?Any suggestions for modding the fan so that it plays nicely with todays delicate electronics? I'd like to use it if possible.

author: ManateeMafia
author_rank: Frequent Contributor
timestamp: February 13, 2015, 02:19:27 am
content: Surge protection or GFCI?Those fans are great. As kids, the only thing we wouldn't put in those fans were our fingers!What kind of plug is on that beast?

author: Drewboy
author_rank: Contributor
timestamp: February 13, 2015, 03:33:12 am
content: Plug is a standard 3 prong, Australian style one.Re surge protector or GFCI, those are units that trip on a surge and then remain off until you reset or replace them yeah?I was hoping for something that would fix the issue so that the surge doesn't occur in the first instance.

author: SeanB
author_rank: Super Contributor
timestamp: February 13, 2015, 04:53:20 am
content: Simplest would be to open it and place a VDR across the mains input and the switch contacts, along with replacing the by now very decrepit mains filter capacitor or filter inside it. Probably needs the split capacitor changed as well, and a check of insulation resistance of the motor and mains lead as well.

author: Seekonk
author_rank: Super Contributor
timestamp: February 13, 2015, 02:08:35 pm
content: I would prefer to place a .22uF X2 type capacitor in series with a 47 ohm resistor in parallel with the motor.

author: Drewboy
author_rank: Contributor
timestamp: February 14, 2015, 07:14:14 am
content: Cheers,I might whip out the oscilloscope and see what works best.

author: sean0118
author_rank: Frequent Contributor
timestamp: February 14, 2015, 07:45:27 am
content: I'm not saying its related to the problem, but have you checked it's still earthed properly?

author: Drewboy
author_rank: Contributor
timestamp: February 15, 2015, 10:17:04 pm
content: Nah it wasn't, a lot of the wiring is pretty badly deteriorated. I'm looking at redoing the lot.
Ethernet Connector Pulled Off IP Phone - Page 1
Forum section: electronics / repair

author: dfmischler
author_rank: Frequent Contributor
timestamp: February 24, 2015, 10:31:26 pm
content: Somebody apparently gave one of the phones at work a bungee-jumping lesson off a counter. I was told that it stopped working, and when I got there the ethernet connector was floating around in the case with the exterior cable still attached. Since the phone gets both power and data over this cable it wasn't working too well.It's just a surface mount connector soldered to the board. I've soldered it back on, and it works, but I'm thinking about gluing the connector down to try and avoid future damage if the same thing happens again (worst case would be ripping pads off the board). What do you think? Leave it alone? Glue it down with something hard (epoxy)? Something soft (RTV)? Or install an external strain relief? Or just make the cable long enough that the case hits the floor before there is any strain on the connector?

author: SL4P
author_rank: Super Contributor
timestamp: February 25, 2015, 02:38:07 am
content: Hard - epoxyLast chance then replace the phone next time it flies !

author: Mr.B
author_rank: Unknown
timestamp: February 25, 2015, 02:47:41 am
content: Quote from: SL4P on February 25, 2015, 02:38:07 amBetween the phone and the counter...

author: Skimask
author_rank: Super Contributor
timestamp: February 25, 2015, 02:50:43 am
content: H.E.B.K.A.C.Hard Epoxy Between Keyboard And Chair

author: anachrocomputer
author_rank: Regular Contributor
timestamp: February 25, 2015, 01:17:09 pm
content: I did a similar repair to a Samsung R519 laptop:http://www.flickr.com/photos/anachrocomputer/6910280415#The PCB tracks had been ripped off too, so I had to wire them back to the ethernet transformer.

author: jlmoon
author_rank: Unknown
timestamp: February 25, 2015, 03:59:06 pm
content: A product called "E6000" should do the trick, better than "Gorilla Glue" in some cases such as this.Available at your local Home Depot store
Remote Garage Door Opener - Repair - Page 1
Forum section: electronics / repair

author: kreetchur
author_rank: Newbie
timestamp: February 14, 2015, 03:52:39 am
content: I am attempting to repair a multicode garage door opener. It looks like this (photo borrowed from other user, link below).https://www.eevblog.com/forum/chat/semefab/The LED lights up, and all of the solder points look fine. There are no obvious broken parts or disconnects, but it doesn't open the door. My identical (and working) remote starter does work.It runs on a 9V battery (battery checked, provides 9.1 volts disconnected, across terminals; 8.6 volts when connected and opener activated)The small black chip is a Semifab 051-8728, 9209-D, and the black block has 10 - 2 position switches to code the output. I have checked the code to make sure that this is NOT the problem.So, it's not the battery (probably) not the code (certainly), and most likely does not have any broken connections. I suspect that the little blue bit (Antennae???) and/or the little green inductor has something to do with this problem.Anybody have any ideas? I'm stumped. Also, I'm not very good at this, so any plans would be appreciated.

author: tautech
author_rank: Super Contributor
timestamp: February 14, 2015, 07:15:49 pm
content: Welcome to the forum.A little history might help.Has it been wet?Has it been dropped?8.6 V when activated seems low? (guess)Drawing too much current, battery low ? ?

author: kreetchur
author_rank: Newbie
timestamp: February 14, 2015, 10:01:17 pm
content: Thank you for the welcomeThe opener may have been dropped, but has not been wet. The reason that I originally thought it was not working was that the small red indicator LED was no longer working. I opened it up and found that one of the legs of the LED was broken. I fixed it with a bit of wire, and did hook it up the right way. The LED lights up when I press the button again, but still no response from the garage door.Other Remote openers are still working; it's just this one.(Thanks for your reply, and tips)

author: G7PSK
author_rank: Super Contributor
timestamp: February 15, 2015, 10:27:01 am
content: Have you tried reprogramming the door to the remote. Many of the gate units I have come across each key fob has to be paired to the opener unit, usually by pressing an internal button and then pressing the remote's button. I have had units loose pairing from being left with a flat battery in a draw for too long or from being dropped, in one case the remote had just been left in a tractor cab in the sun for a day and it got un-paired from that.
Magix digital satellite receiver, Model: mgx-9800 - Page 1
Forum section: electronics / repair

author: repairs online
author_rank: Newbie
timestamp: February 15, 2015, 07:58:11 am
content: This FTA (Free to Air) digital satellite receiver, model mgx-9800 by Magix ( a korean company) on pluging the mains power cord, has the red led switched on, steady red, the green led, designated as lock, flashing on/off several times and then steady green and the 2 dots, : , in the channel number display, ON.The power button has no effect.Checked all power supply output to the main board, all OK.Any suggestions ...

author: tautech
author_rank: Super Contributor
timestamp: February 15, 2015, 08:08:49 am
content: Welcome to the forum.Maybe it's waiting for you to access the menu and set the LNB up then search for stations.Is it on the bench or in a "working" installation?

author: repairs online
author_rank: Newbie
timestamp: February 15, 2015, 08:27:55 am
content: OK/MENU button no effect. In fact, no AV output signal from the satellite receiver to the TV. The switch ON/OFF button can neither switch ON or OFF the receiver. Normally, it should display a channel number when switched on.
mechanical keyboard pcb repair. - Page 1
Forum section: electronics / repair

author: radish
author_rank: Contributor
timestamp: February 15, 2015, 05:27:43 am
content: hey guys. i was trying to repair a broken mangled micro usb connector, got startled and my hand slipped and the resulting scratch happened. now im not super fimiliar with electronics and to be honest im fairly new. im pretty good at soldering though... just a bit jumpy.anywho... can anyone help me identify what part i destroyed? on the left is my board cleaned up, the right shows a board with the pcb that isnt damaged.on a different forum it was suggested that the part has a zero on it meaning its a revision. considering that this is v1.4 of the pcb that makes sense. is there any way to confirm that its just a bridge that i destroyed?if there is more info i remember i would add it but thats all i can thing off.here is a scan of the board.

author: c4757p
author_rank: Super Contributor
timestamp: February 15, 2015, 05:31:23 am
content: Yup, you just knocked a jumper off. The "L1" designator suggests it was supposed to be an inductor/ferrite bead/choke/pick-your-favorite-name to filter that line, and then they decided they didn't need that filter and just put a cheap bridge there. You can use a blob of solder or a bit of wire.

author: radish
author_rank: Contributor
timestamp: February 15, 2015, 05:37:47 am
content: ok thanks for that, let me bridge it and fire it up.hopefully it wont catch fire.

author: miguelvp
author_rank: Super Contributor
timestamp: February 15, 2015, 05:48:57 am
content: Quote from: radish on February 15, 2015, 05:37:47 amIt's just a zero ohm resistor, so pretty much a jumper.

author: radish
author_rank: Contributor
timestamp: February 15, 2015, 07:14:08 am
content: great success! thanks guys. made a solder bridge and everything worked great!
BT131 09H Triacs logic level - Page 1
Forum section: electronics / repair

author: spike1947
author_rank: Contributor
timestamp: February 15, 2015, 09:58:46 am
content: Hi AllThanks for letting me join your forum , let me start by saying that I am not into Electronics per se , my hobbie is really repairing Laptops , with having to solder up some very ,very tiny components ( I use a microscope for that small ic parts ) , just leting you know I have a bit of knowledge of circuit boards .well back to the point in question , my daughter has one of those fancy lights that is touch sensitive for switching on and to go from low to high with tapping the lamp holder 1,2,3 times something like that anyway , well it stopped doing what it is supposed to do , so me being me not to bin it, opened it up ( see pic uploaded ).pic shows blown Triac , now I have ordered a "BT131-600,412 TRIAC 600V-1AMP SOT54" will this be a replacement for my "BT131 09H Triacs logic level " and off course any other info you can give me .thanksspike

author: mij59
author_rank: Frequent Contributor
timestamp: February 15, 2015, 10:39:31 am
content: The specs are nearly identical, but why has the triac blown ?

author: SeanB
author_rank: Super Contributor
timestamp: February 15, 2015, 11:02:08 am
content: I would guess the lamp in the unit is either a CFL lamp, or the original lamp was a 150W one, and the triac overheated from too much current. The CFL lamp will kill it from the switching current spikes as the triac tries to drive it and the 150W lamp is just too big. As the board is scorched from heat around the little triac i would guess it was a too high power lamp.For instant kill it would be an incandescent lamp that failed at switch on and was short circuit during it's failing.

author: spike1947
author_rank: Contributor
timestamp: February 15, 2015, 02:10:23 pm
content: HiThanks for your replies , She did say that the bulb made a noise when it blow , but she has thrown that bulb away , so I am not sure what size bulb to put in , I would of thought 150W would be way to high , it is only a bedside table lamp I would of thought a 60W incandescent would be Max ! , or a 20W Halogen ! .cheersspike

author: SeanB
author_rank: Super Contributor
timestamp: February 15, 2015, 03:00:34 pm
content: So a blowing bulb did it in. Buy a few spare ones then, so that you can replace it next time when it blows. Otherwise add a NTC thermistor in series with the mains input, to keep the spike down on turn on, which both helps protect the triac and prolongs lamp life considerably. 4R7 or 10R one from an old PC power supply ( black or green 2 legged unit in the mains feed ) will work here.
Diagnose Samsung Plasma TV - Page 1
Forum section: electronics / repair

author: TheRuler8510
author_rank: Regular Contributor
timestamp: February 14, 2015, 12:29:01 pm
content: Is there any way to diagnose such that the plasma panel itself can be ruled out as the cause of failure? Power supply voltages are all correct.The gamble is getting a new board or two then finding out the panel itself is bad. So I'd like to first rule out the panel.Any ideas? How often do the panels go bad? Or is it a rare case that panels go bad?Thanks,

author: fable
author_rank: Regular Contributor
timestamp: February 14, 2015, 01:07:52 pm
content: Hi.Most common failure i plasma tv are y-sus and z-sus boards.Check fuses on them
HM1800 BT Headset refuses to run off 4v power supply instead of li-ion battery? - Page 1
Forum section: electronics / repair

author: salil
author_rank: Regular Contributor
timestamp: February 09, 2015, 10:11:03 am
content: I removed the single cell li-ion battery soldered to the circuit board of aSamsung HM1800 bluetooth headsetand replaced it with a 4.1v DC power supply. Unfortunately, the device refuses to power on reliably. I got it to power on once or twice, but it was performing erratically. I put the included battery back and it of course works just fine. I'm using a 5v/1A power supply and stepping the voltage down to 4.1v with an NTE956 regulator and some caps & resistors. The current draw when using the battery has never exceeded 0.5A when I measured it.Does anyone have any idea what could be going on here?

author: janoc
author_rank: Super Contributor
timestamp: February 09, 2015, 11:11:16 pm
content: 4.1V looks quite high for a single Li-ion cell. Those are around 3.7V usually. Are you sure you are not giving it too high voltage?

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: February 10, 2015, 02:59:20 am
content: Quote from: janoc on February 09, 2015, 11:11:16 pm3.7V is the nominal voltage. Fully charged they go to 4.2V.

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: February 10, 2015, 03:02:46 am
content: Quote from: salil on February 09, 2015, 10:11:03 amWhat's with the unrelated video link?

author: amyk
author_rank: Super Contributor
timestamp: February 10, 2015, 04:18:49 am
content: Quote from: Alex Eisenhut on February 10, 2015, 03:02:46 amApparently it's what he is trying to use the BT headset for.It could be drawing far more current than 0.5A in brief pulses, which can't be seen without a scope.

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: February 10, 2015, 05:14:58 am
content: Quote from: amyk on February 10, 2015, 04:18:49 amGuess I'm not too patient. I see some unrelated video and I just closed it.Yeah we'd need to see what this mysterious regulator with "some caps & resistors" actually looks like, how long the wires are, etc. Probably losing regulation because of poor transient response.And how the current was measured, with what, etc...

author: Seekonk
author_rank: Super Contributor
timestamp: February 13, 2015, 02:12:01 pm
content: I would think the cap at the battery side needs to be a LOT BIGGER. I suspect it can't handle the surge.

author: Dragon88
author_rank: Regular Contributor
timestamp: February 13, 2015, 06:40:11 pm
content: What's the dropout voltage of the regulator? Is it greater than 0.9V?What's the measured output voltage of your regulator circuit with a 0.5A load?

author: daveshah
author_rank: Unknown
timestamp: February 13, 2015, 07:42:54 pm
content: I don't think that the regulator is an LDO - the data sheet doesn't even give a dropout voltage spec - so the dropout voltage is likely to be about the two volts or so. Have you measured what voltage it is actually outputting?
amp distorsion - Page 1
Forum section: electronics / repair

author: Bloe
author_rank: Newbie
timestamp: February 12, 2015, 09:18:08 pm
content: hi i got an auna amp 7100 whit beng v9 speakers and on all the channels and inputs are a distortion noiseaccept on the normal stereo Channel when i crank the vol, up also the noise crank't up but when i press the mute its a total silencethe noise is so damm loud that i come crazy, the amp is in my home setup , tv, pc, radio, blu-ray etc...
HP 6825A Bipolar Power Supply  - repair advice - Page 1
Forum section: electronics / repair

author: tony t
author_rank: Newbie
timestamp: February 11, 2015, 05:18:28 pm
content: Unit description: single +/-20V 2A power supply / amplifierBought a HP 6825A on eBay. Unit mostly works. Load regulation and current limit works as expected (LED turns on). Problem I discovered is thatpositiveoutput can only deliver about 1A before voltage regulation stops and voltages does not increase. The Current Limit LED does not turn on, indicating that the "current limit circuit" is trigging and limiting output at 1A (I think). When I dial innegativevolts, the unit can deliver over -2A as expected. Load regulation is good for negative load.Input filter caps are good… All power rails are at correct voltage when loaded. Since this unit is 24 years old, it’s possible that some transistors or opamps are not working not 100% but have not completely failed. Could one of the output transistor pairs be open? How about weak driver transistors? Don't want to tear the whole thing apart if not necessary. Heavy transformer, etc...Perhaps other 6825A owners can chime in and share their repair findings. Looking forward to any advice.

author: rastro
author_rank: Frequent Contributor
timestamp: February 11, 2015, 08:21:45 pm
content: Hello Tony,I have an HP 6826A +/- 50V Bipolar PWS (similar units). While doing some functional tests it appeared to function OK . However, while straightening out a bend frame it received in shipping I noticed a charred part on the bottom PCB. This was caused by R60 a 1-ohm 3W resistor that had changed value (reading close to 1.5-ohm) and heated up. As you look at the front of the unit this resistor is on the left side of the bottom PCB near a large relay. I replaced it to prevent further damage to the PCB.Anyway, I may not be an issue on your system but probably worth checking.

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: February 11, 2015, 08:37:18 pm
content: Manual's freehttp://www.excaliburengineering.com/media/datasheets/Agilent_6825A_usm.pdfmore of a 40 year old design. Should be relatively simple to poke around in there, also old carbon comp resistors can drift in value (mostly up it seems).
Power Distribution device Z-Line PC302 - Page 1
Forum section: electronics / repair

author: Coliban
author_rank: Regular Contributor
timestamp: February 07, 2015, 11:09:34 am
content: Hello,a friend gave me a PD Device, a power distribution from "Z-Line" PC302. It has a three phase input and 14 Outputs (12 switched, 2 unstitched on the back). I opened it and a cable, signaling the main power werde burned. I would like to solve two problems:1. Repair the burned cable, which is no problem, but find perhaps other failures2. rebuild the PD so i can serve it with normal current (not three phase, but one). (I though that i could bypass the threepase input and connect the 220V directly, behind the 3-phase converter t use it as a normal 220V power distribution)

author: Coliban
author_rank: Regular Contributor
timestamp: February 07, 2015, 12:44:20 pm
content: There are 3 Relays, G7L-1A-TUBJ-CB, one for each phase.http://www.mouser.com/ds/2/307/G7L_0513-253197.pdfBuild quality seems to be rock solid.

author: Coliban
author_rank: Regular Contributor
timestamp: February 07, 2015, 07:24:20 pm
content: I divided 220V into 3-phases, so the PC302 would think, it has 3 different phases and ist working now on all 12 outlets. I need this power distribution for my desktop project (https://www.eevblog.com/forum/projects/building-a-micro-workbench-how-do-your-workbenches-look-like/msg593440/#msg593440). Now i have a small power distribution for 12 sockets and devices, that more than i need :-)

author: SeanB
author_rank: Super Contributor
timestamp: February 08, 2015, 10:18:11 am
content: You might wish to consider wiring the neutral to the neutral, and the 3 lives to live. As it is there all the outputs have a reversed live and neutral. Will work but if you have polarised mains ( in Germany no) plugs and sockets it will be an issue. At least you have 3 MOV's as protection now on the input side.

author: Coliban
author_rank: Regular Contributor
timestamp: February 08, 2015, 10:28:01 am
content: Hello SeanB,maybe i don not understand it correct, but what do you mean that live and neutral are reversed? As it is now, i have live to live and neutral to neutral wired. (The input side is three times protected now, thats right, but i think about a lower protection than 16A.)

author: SeanB
author_rank: Super Contributor
timestamp: February 08, 2015, 12:06:30 pm
content: On the 3 phase input you show you wired the 3 phases to the incoming mains neutral ( blue) and the brown incoming live to the neutral common terminal of the PDU, with the green/yellow PE connected correctly. That then reversed the output plugs polarity. As the designers of the PDU have switched both line and neutral to the output sockets you will not have an issue with the outlets being live even when switched off.

author: Coliban
author_rank: Regular Contributor
timestamp: February 10, 2015, 08:35:08 am
content: Hello SeanB,of curse, you are right. I will change the color, but when the plug is plugged the other way round in the socket, then the phases also will change, but that is not an issue, as you mentioned.regards
Samsung 42" Plasma (PS-42Q91HD) - 56K beware - Page 1
Forum section: electronics / repair

author: FearTec
author_rank: Regular Contributor
timestamp: February 06, 2015, 11:09:40 pm
content: My brothers 7yo Samsung TV has died with the issues similar to the bad caps issue (sometimes fails to turn on and if it comes on it will turn on again and makes clicking sounds).I opened the TV and checked for bad caps but nothing out of the ordinary. It mostly has ceramic caps.I will follow the power switch back and see if it is ok (not burnt out) and then trace back to the power board. it looks like the power button connects near the TV decoder board so maybe the chip is dead.Q1) Does anyone have a service manual for this TV?Download:http://simon.fearby.com/temp/eev/marctv/IMG_2022.JPGDownload:http://simon.fearby.com/temp/eev/marctv/IMG_2022.JPGDownload:http://simon.fearby.com/temp/eev/marctv/IMG_2022.JPGDownload:http://simon.fearby.com/temp/eev/marctv/IMG_2022.JPG

author: David_AVD
author_rank: Super Contributor
timestamp: February 06, 2015, 11:33:58 pm
content: I have an LG 42PT250 that refuses to start up. In my case the clicking is a relay on the power supply board.After some inconclusive searching I changed all the electrolytic caps on the power supply board, but it's still the same.Some sources pointed to a fault on the YSUS board(s) causing the power supply to shutdown. Maybe search online for something along those lines?

author: Bryan
author_rank: Frequent Contributor
timestamp: February 08, 2015, 10:16:51 am
content: I enjoy following the videos of NorCal715 on utube. I am sure if you reached out to him he would be able to point you in the right direction as to trouble spots with this particular unit.https://www.youtube.com/user/norcal715

author: janoc
author_rank: Super Contributor
timestamp: February 08, 2015, 12:53:06 pm
content: Quote from: FearTec on February 06, 2015, 11:09:40 pmMake sure that you check the caps using an ESR meter. They don't have to be visibly bulging or leaking to be bad. Capacitance meter doesn't help neither - I have pulled quite a few caps that still have the rated capacity and everything, but sky-high ESR.Usually the caps going bust are the low voltage ones at the output of the PSU - that would be the first thing to re-check. The clicking you are hearing could be some sort of safety relay turning the thing off. Sometimes even the coils in the PSU could make such noise alone (had an ATX PSU doing that).

author: Rasz
author_rank: Super Contributor
timestamp: February 09, 2015, 03:24:32 am
content: Quote from: FearTec on February 06, 2015, 11:09:40 pmhow?start with voltagesplasmas = sustain boards dying

author: janoc
author_rank: Super Contributor
timestamp: February 09, 2015, 10:02:24 pm
content: Quote from: Rasz on February 09, 2015, 03:24:32 amThat and Samsung notorious CapXon (also known as Crap-xon) capacitors in their PSUs. If the TV is using those, change them without even measuring - they reliably die after the 6-7 years.Dave has a video on how to find bad caps using an ESR meter:http://www.eevblog.com/2012/10/06/eevblog-365-esr-meter-bad-cap-monitor-repair/
JBL CS300.1 repair. - Page 1
Forum section: electronics / repair

author: ResR
author_rank: Regular Contributor
timestamp: February 15, 2015, 08:01:05 pm
content: I got a JBL CS300.1 audio amplifier for repair, it's main problem is that there's no audio at the output and three indicator LED's (in series) flash. First time taking it apart I found R31 10 ohm resistor burnt down, I replaced it with a working one from an old CFL but the fault was still there. The power supply is in specifications, I tested all the larger transistors and capacitors for faults finding nothing.The PDF of the device didn't give much clue either, even the PCB drawings are a little bit different:http://www.jbl.com/resources/Brands/jbl/Products/ProductRelatedDocuments/en-US/ServiceManual/CS300p1%20sm.pdfAny ideas where to look for?

author: Seekonk
author_rank: Super Contributor
timestamp: February 15, 2015, 08:13:51 pm
content: The LED is flashing because the power supply isn't working, it senses the negative leg. I didn't see where the 10 ohm was, didn't look that hard. Something is wrong with the inverter section.

author: ResR
author_rank: Regular Contributor
timestamp: February 15, 2015, 08:57:56 pm
content: I think I found the result of the problem - Q12, Q15 and Q19 mosfets are not driven while Q11, Q13 and Q18 mosfets are turned on with gate pin voltage almost same as source pin and getting warm 30-31C without heatsink, 0,5 and 0,8 volts at the output of inverter. R31 is tied to ground at the power supply area.
audio amplifier repair question. - Page 1
Forum section: electronics / repair

author: Oddball
author_rank: Contributor
timestamp: February 12, 2015, 02:19:43 pm
content: Hello, recently I have been repairing an 5.1 surround amplifier (onokyo ht r8230). I have the service manual with detailed schematics but I have a question on the block diagram. From what I see the sound from the RCA jacks / tunner is amplified by 6db then attenuated by 18 db then amplified again by 27 db in the driver amp. Question is, why amplify by 6db then attenuate by 18? Why not just attenuate by 12db? Ive attached screen shots of the block diagram below, if need be I can post detailed transistor level schematics from the service manual.

author: PA0PBZ
author_rank: Super Contributor
timestamp: February 12, 2015, 02:34:06 pm
content: If you are referring to the "0-18dB" text I'm sure you should read it as "0 to 18" and not -18.

author: Oddball
author_rank: Contributor
timestamp: February 12, 2015, 02:35:46 pm
content: In that case, what is 0/6db supposed to mean?

author: PA0PBZ
author_rank: Super Contributor
timestamp: February 12, 2015, 02:39:27 pm
content: Quote from: Oddball on February 12, 2015, 02:35:46 pmswitchable between 0 and 6 dB, unlike the others that have a variable resistor in the input.

author: Oddball
author_rank: Contributor
timestamp: February 12, 2015, 02:47:35 pm
content: Well the power amp has fixed gain of 27dB...which means at standard 1.4vrms RCA voltage levels the lowest voltage it could output would be 31 volts rms, which seems unlikely, how exactly is volume controlled then?

author: SoundTech-LG
author_rank: Frequent Contributor
timestamp: February 12, 2015, 03:03:51 pm
content: Volume is controlled by that master volume chip, which in your block diagram not everything is shown, there is much more detail on the actual schematic diagram. do you have it???

author: PA0PBZ
author_rank: Super Contributor
timestamp: February 12, 2015, 03:12:59 pm
content: Just on the back of the envelope: If you have 100W output and 27dB gain you need an input of 200mW.Since the RCA will have an input signal a lot lower than that you will need additional amplification. If you know the input impedance you can calculate the input power for 1.4V

author: Oddball
author_rank: Contributor
timestamp: February 12, 2015, 03:16:30 pm
content: I will attach photos of the preamp, note the mux/volume chip is actually broken (BD3811K1) and im building logic to bypass it.I'm on my phone at the moment and I can post more detailed pictures when I get home.
telescopic antenna  - Page 1
Forum section: electronics / repair

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: July 08, 2014, 04:54:14 pm
content: Hi there,Repairing my vintage Electronics International Model 1829 multi-band radio.It uses twin telescopic antennas, but the swivels are also retractable.I've looked but I can't find a supplier or part number for this antenna type.I know I can get external swivel antennas but then they don't retract all the way into the radio body.This radio has nostalgic/emotional value to me and I'd really like to keep it original looking.Thanks,Alex

author: motocoder
author_rank: Unknown
timestamp: July 09, 2014, 01:30:51 am
content: I doubt you will be able to find new parts to replace. You might try a more radio-oriented forum, maybe eHam.net orwww.radiomuseum.orgGood luck!

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: July 09, 2014, 05:51:23 pm
content: Quote from: motocoder on July 09, 2014, 01:30:51 amYeah, the worst part is that I want to replace the bulkhead part as well.I guess the bulkhead breaks easily and the swivel part yanks out, which is why the antennas are missing...Sigh...

author: Marc M.
author_rank: Regular Contributor
timestamp: July 09, 2014, 08:50:55 pm
content: Another great place to look for help would be:http://www.antiqueradios.com/forums/index.phpIt's one of the best forums on the net for all things old and tubey

author: emultra
author_rank: Newbie
timestamp: February 07, 2015, 03:45:26 am
content: I just picked up one of these radios at the thrift store.It's in good condition although it smells like cigarette smokeAlso, I think one of the antennas has been replaced--> it's not the same as the other, nor is it fully retractable like the original, (sticks up about 6")though it does have one original.I've kinda been hoarding radios lately so... if you'd like a working replica of your own, email me! I'm in Ontario, so the shipping shouldn't be too much.
Präcitronic GSR 3000 service manual - Page 1
Forum section: electronics / repair

author: Guni
author_rank: Regular Contributor
timestamp: February 06, 2015, 09:51:45 pm
content: Hello,I've bought old lab power supply GSR 3000, made by (East Germany) Dresden Präcitronic. Probably from mid '80. According to seller's description it's not power on (I don't have it yet). Maybe just burned fuse but I don't think so. Anyway I'm looking for service manual or other document about repair.Thx for any information.
Mystery 12 pin USB/audio connector? - Page 1
Forum section: electronics / repair

author: salil
author_rank: Regular Contributor
timestamp: February 06, 2015, 07:31:17 am
content: I purchased one of those GSM GPS locator things on eBay a couple years ago and it uses this strange 12 pin connector to charge via usb. Unfortunately, I lost the cable that came with it but i do have a headset that came with it which has the same connector on it. What could this be? It's certainly not micro usb, though it is similar in size (slightly wider). Looks like 12 pins. Any ideas?

author: Zarhi
author_rank: Contributor
timestamp: February 06, 2015, 08:17:15 am
content: This looks like old Samsung phone connector:http://www.amazon.com/Samsung-APCBS10UBE-Data-Cable/dp/B001I45EGC

author: mikerj
author_rank: Super Contributor
timestamp: February 06, 2015, 12:22:01 pm
content: Is it a 12 pin "Mini USB"?

author: wraper
author_rank: Unknown
timestamp: February 06, 2015, 12:45:42 pm
content: Quote from: Zarhi on February 06, 2015, 08:17:15 amNo it doesn't.

author: gman4925
author_rank: Regular Contributor
timestamp: February 06, 2015, 01:29:32 pm
content: http://www.digikey.com/product-detail/en/2129295-2/A103877-ND/2743538
SCHAFFNER NSG5000 - Page 1
Forum section: electronics / repair

author: pspinoso
author_rank: Newbie
timestamp: February 06, 2015, 12:51:00 am
content: i have a Schaffner NSG5000 and i need to know where i can find a company that located not far from EL Paso TX, or Cd Juarez Mexico, for an evaluation
Unknown small trafo parameters RCILF1086D8 JSI 9838  - Page 1
Forum section: electronics / repair

author: eneuro
author_rank: Super Contributor
timestamp: February 05, 2015, 04:35:02 pm
content: Hello,I've such unknown small trafo parametersRCILF1086D8 JSI 9838and unfortunatelly search engine says nothing about it, but it would be nice to have some data, while want to reuse it it another project (simple GDT to drive AC mosfsts switch gate ):Probably it is from old PC power supply-I'm not sureSuccessfully, in simple SMPS at 400kHz was able to output around 10.5V from 5V LM7805 and turn on AC mosfets switch, but wanted to tune this frequency and probably without knowledge of its core material, it will be difficult to do more sophisticated research....

author: SeanB
author_rank: Super Contributor
timestamp: February 05, 2015, 05:07:53 pm
content: Looks like a base drive transformer for a CRT monitor or TV set. Turns ratio looks about right, with it driving a transformer base with around 3A peak to turn it on, while it is powered from a 15V rail.

author: eneuro
author_rank: Super Contributor
timestamp: February 05, 2015, 06:59:34 pm
content: Quote from: SeanB on February 05, 2015, 05:07:53 pmAnyway, removed a few turns (maybe even half) from one side and both sides looked to have the same number of quite thick turns, when taken it from maybe CRT monitor-I had two of them recycled.It has square core about 5mm x 5mm and about 10mm between bottom legs, so it is quite small.Any ideas what could be its working frequency?

author: bktemp
author_rank: Super Contributor
timestamp: February 05, 2015, 09:56:11 pm
content: Looks like a common mode choke.
remove this topic - Page 1
Forum section: electronics / repair

author: treniora
author_rank: Newbie
timestamp: January 04, 2015, 08:53:43 am
content: I have problem with wrong setpoint ( I think that is wrong resistor), can someone help me with a detailed photo of the PCB?

author: kevbry
author_rank: Contributor
timestamp: February 05, 2015, 05:27:19 pm
content: This is the board from my 898D. Blue pot close to the left side of the board is for the iron, the identical one in the middle is for hot air. Turning clockwise makes the tip cooler, counterclockwise makes it hotter. Mine was something like 200C out of calibration when I bought it... would actually burn the board when set to 300.My Amazon review:http://www.amazon.ca/review/ROE83RPPOHV1E/

author: kevbry
author_rank: Contributor
timestamp: February 11, 2015, 04:31:23 pm
content: I found a youtube teardown of the D+ model here:The board looks pretty close to identical to the one from my 898D. Does yours have a different board? Even if the iron is different the driver is probably very similar, and can most likely be adjusted with a trim pot on the board just as mine was.
GoPro Hero 4 Silver Rear LCD Replacement - Page 1
Forum section: electronics / repair

author: pyr0b0y
author_rank: Newbie
timestamp: February 05, 2015, 06:53:18 pm
content: Hey Guys,I recently cracked the rear LCD screen on my Hero 4 Silver. I was able to source a replacement screen, but am having a little trouble getting to the screen itself.I watched the teardown video posted on the EEV blog, but it does not go into detail about removing the battery compartment or the screen itself. Any help would be appreciated!
Sony BRC-H700 service manual - Page 1
Forum section: electronics / repair

author: Towger
author_rank: Super Contributor
timestamp: February 05, 2015, 03:24:19 pm
content: Hi,Does anyone have a copy of the Sony BRC-H700 service manual?Towger.

author: baltersice
author_rank: Regular Contributor
timestamp: February 05, 2015, 03:33:47 pm
content: Sorry, no ...But I repaired an SNC-DH260 once:Yours is 10 times as expensive though and has RGB output, while mine is network-attached, so they are probably different in every single detail

author: Towger
author_rank: Super Contributor
timestamp: February 05, 2015, 04:24:55 pm
content: These are 100% different. I have worked with the EVI D30/1/L and EVI D70s before, which are closer to the BRC versions, but again a world apart in mechanical complexity.I picked up two on ebay for 1p, in a state of disarray.It would appear someone has dismantled the tilt mechanisms on both of them and both are missing parts, but some of which came in a plastic bag full of washers, cogs and bearings etc....The goal is to get one working, but I don't know if i have enough bits, or what the under lying faults were. Sony still sell parts for them, but it looks like many of the custom parts are no longer available. Still one of these cameras with just pan working would be an interesting project.
MTS-4000 YIG oscillator - Page 1
Forum section: electronics / repair

author: mazurov
author_rank: Frequent Contributor
timestamp: February 03, 2015, 06:43:00 pm
content: Hello all!I bought this thing (quite inexpensively) on eBay. According to the seller it is 4-ish GHz YIG oscillator. Googling for info on the label (first pic) yields nothing. I'm currently studying this paper ->http://www.vhfcomm.co.uk/A%20Simple%20Approach%20tyo%20YIG%20Oscil.pdf(mine looks similar to Fig.17) while waiting for u.fl to SMA cables to arrive. I'm not familiar with this type of equipment and was wondering if it would be OK to open it instead of trying to figure out connections with test instruments. If anyone is in possession of manufacturer's data on this unit, please share!Thank you for your time!Regards,Oleg.

author: N2IXK
author_rank: Frequent Contributor
timestamp: February 04, 2015, 05:30:22 pm
content: Aside from being careful of tiny connections and delicate parts in general, you should know that the "BeO" on the label refers to Beryllium Oxide, used somewhere in the internal construction.An innocuous looking white ceramic material, it is VERY toxic if abraded and inhaled. Unless you are planning on grinding or machining the internal parts, you should be fine. It is used where an electrical insulator with good RF properties also needs to be a good thermal conductor. Probably located between the heater element and the YIG element itself.

author: mazurov
author_rank: Frequent Contributor
timestamp: February 05, 2015, 04:53:58 am
content: Thanks! I'll be careful. Sadly it seems this is not an oscillator but rather a filter for which I don't possess a signal source. Back to eBay...
Fluke 8060a Meter:  Looking for some MAC chips (Fluke P/N: 612713) - Page 1
Forum section: electronics / repair

author: Rosebud41
author_rank: Newbie
timestamp: February 04, 2015, 10:16:25 pm
content: My first post...so here goes !I have a few Fluke 8060A's kicking around.....which are complete, in excellent condition, w/functional display's...except they have dead MAC chips in them (Measurement Acquisition Chip - Fluke P/N: 612713).NOTE: After borrowing a functional chip, I confirmed that all these meters work perfectly...Maybe someone has a small cache of these chips lying around...?More likely...the best source of these chips are other 8060A's. Perhaps there may be hobbyists/tech's out there with old 8060A's with the reverse scenario (missing buttons, crappy cases, dead displays)...who'd like to get a few buck's for these DMM carcass's...allowing me to harvest the MAC chip, and Frankenstein my units back to life !Let me know....message me thru the EEV forum...thanks.CJ.

author: retiredcaps
author_rank: Super Contributor
timestamp: February 04, 2015, 10:37:52 pm
content: Quote from: Rosebud41 on February 04, 2015, 10:16:25 pmDead as in completely non-functional that it doesn't even power up and give a display?BTW, if you are fan of the 8060A, you may be interested in these threads.https://www.eevblog.com/forum/testgear/old-fluke-multimeters/http://www.theamphour.com/180-an-interview-with-dave-taylor-multi-talented-meter-maker/http://mrmodemhead.com/blog/fluke-8060a-repair/
Fluke 336 DMM - Page 1
Forum section: electronics / repair

author: gpser
author_rank: Newbie
timestamp: February 04, 2015, 07:29:12 pm
content: My Discontinued Fluke MM was dropped and quit. Any suggestions? Batteries OK, contacts OK.

author: tautech
author_rank: Super Contributor
timestamp: February 04, 2015, 08:13:19 pm
content: Welcome to the forum.Have you opened it up to look for anything obvious?With impacts heavy components can dislodge from the PCB, breaking leads or tearing pads.Sometimes easy to repair.

author: lowimpedance
author_rank: Super Contributor
timestamp: February 04, 2015, 10:17:29 pm
content: Otherwise be more specific and perhaps some photo's of inside and out.If it just quit and its old then maybe its time for something new!.
Power Designs 6050A - Page 1
Forum section: electronics / repair

author: Luap2
author_rank: Contributor
timestamp: January 28, 2015, 09:20:59 pm
content: I am in need of some Info to fix this. From the manual I need CR23 and CR24, Silicon Rectifiers part # TS44 or GI44 and CR25 a silicon controlled rectifier Part #C13F . As far as I can tell these are unique part # to Power Designs. Any one know what can be substitutedthat can be bought now days or is there a PD parts X-over pub. some where or where to get old/new PD partsThanksPaul

author: idpromnut
author_rank: Unknown
timestamp: January 28, 2015, 11:38:16 pm
content: Fromhttps://www.eevblog.com/forum/testgear/help-with-power-designs-6050c/, try a 1N4004. They look like "standard" basic switching diodes from the schematic. The only thing that you might want to check is that their forward voltage drop is near 0.6V each (they look to be used to bias the base of Q18. Also, I noticed the nasty scorch marks around R58; that is part of the crowbar circuit. Makes me think that the supply took a nasty over voltage on the output.

author: Luap2
author_rank: Contributor
timestamp: January 29, 2015, 02:53:49 am
content: Idprmnut Thank you for the help that takes care of cr23 and cr24 I thought/ hoped they were a basic diode now for the cr25 the SCR maybe some one knows what can be used thereLuap

author: idpromnut
author_rank: Unknown
timestamp: February 02, 2015, 01:20:57 pm
content: I have the manual for this model at home; I'll look up CR25 for you tonight.

author: Luap2
author_rank: Contributor
timestamp: February 04, 2015, 05:51:59 pm
content: Got it working. Thanks to idpromnut
Anyone suggest an equivalent for a 2SC4001 NEC power transistor that's gettable? - Page 1
Forum section: electronics / repair

author: bcg
author_rank: Newbie
timestamp: February 04, 2015, 02:39:47 am
content: It's for a colour gun on the neck board of an arcade game CRT.I've ordered some from china but a month later I'm still waiting.Since I'm new to all of this, can anyone suggest the best place besides RC to buy in or near australia? I've plugged the values in to the RC website and it's not returning anything.Thanks,Brad

author: jlmoon
author_rank: Unknown
timestamp: February 04, 2015, 03:01:56 am
content: 2SC 2688 1st choice;NTE 157 last choiceSpecs@25 CVcbo 300VVceo 250VIc 100mAPd or Pc 1.3WattsTjunction 150C maxIcbo .1 uAVcb 200Vhfe (gain) 200 for Vce 10V ~ Ic 10mAfreq ~ 300MhzComp > 2SA1546
Motorola 1820-0119 vs Motorola 1820-0232;  Solved, Thx  - Page 1
Forum section: electronics / repair

author: Electro Fan
author_rank: Super Contributor
timestamp: February 03, 2015, 11:23:25 pm
content: Anyone know where to find the specs on these, or if they are interchangeable, of what the differences are?Thanks, EF- Figured this out. Thanks
EWM Tetrix 180 Tig welder repair - Page 1
Forum section: electronics / repair

author: Xaero1982
author_rank: Contributor
timestamp: November 15, 2014, 07:43:03 pm
content: I am trying to repair an EWM Tetrix Tig welder from around 2009.The welder powers on, but only displays error code E 5 - overvoltage. The manual says to check mains voltages, but that is within spec.Does anyone have any hints about where to start looking? The schematics in the manual are very simplified, so I'm a bit stuck.This thing is a pain to disassemble, so I want to take some more measurements before I start tearing it apart. Because of that, I only have a fewimages of the main power board while in the machine.I know it's not much info, but any hints would be very appreciated.Operators manual can be found here:https://www.ewm-group.com/ewm-data/partner-web/Betriebsanleitungen/099-000097-EWM01.pdfError codes on page 74Schematics on pages 79-80

author: Xaero1982
author_rank: Contributor
timestamp: November 16, 2014, 02:38:09 pm
content: Took some quick measurements today:AC input - 230.5VUD+ to UD- = 320V DCUD+ to PE = 215V DCUD- to PE = 105V DCSPW+ to SPW- = 320V DCSPW+ to PE = 215V DCSPW- to PE = 105V DCCould not get any reading between TP and TM

author: Xaero1982
author_rank: Contributor
timestamp: November 18, 2014, 08:57:41 pm
content: After e-mailing EWM, I measured between pins 5 and 6 on connector X1. (Lower left) This was supposed to give -15v, but I measured -30v and decreasing.Pin 5 (UZWK) comes from the marked pin on the transformer, and pin 6 seems to go through the five caps and to the same area.I have desoldered and tested the MOSFET and the black diodes in the area, and they seem fine. All of the caps look good, but I haven't tested them yet.Any input on what could be wrong would be appreciated.

author: mjrpainless
author_rank: Contributor
timestamp: November 18, 2014, 10:35:02 pm
content: Buy seem fine, do you mean that they looked fine, or they actually tested fine?

author: Xaero1982
author_rank: Contributor
timestamp: November 19, 2014, 06:41:51 am
content: The MOSFET turns on and off, and the diodes measure ok.

author: Xaero1982
author_rank: Contributor
timestamp: November 30, 2014, 05:51:38 pm
content: Connected my oscilloscope to the -15v line before filtering, and got this strange waveform. Then I connected my scopemeter to the primary side of the transformer and the waveform is similar.Is this to be expected, or should I investigate this further?

author: poxxxy
author_rank: Newbie
timestamp: February 03, 2015, 12:47:41 am
content: Any other boards in there?Perhaps one with more mosfets and heatsinks or is it an IGBT based welder?I have problems with a chinese build welder myself here and hoping I may find some help.

author: LabSpokane
author_rank: Super Contributor
timestamp: February 03, 2015, 03:38:46 am
content: If the voltage is incorrect at the current transformer X1, wouldn't be a safe assumption that the problem lies between there and the mains input?