hybridfree/eevblog-posts huggingface dataset:
Laptop Charger Issues - Page 1
Forum section: electronics / repair

author: J.Xerneas
author_rank: Contributor
timestamp: September 03, 2015, 10:38:04 pm
content: Hi. This is my first post. I have a HP Pavilion dv6. It has a charging issue that I can't see to solve. When I plug in the original charger it doesn't want to charge the laptop. I checked to see if the charger was working. I measured it with my Multimeterand it was putting out 18.9volts 3.5amps which it is supposed too. So it's not the charger. I used another charger For the same type of computer and it Worked to charge my laptop. So it's not the computer. I don't know what's going on and I can't seem to figure it out.Any help will be great. I don't want to but another charger if I don't have too.

author: wraper
author_rank: Unknown
timestamp: September 03, 2015, 10:50:48 pm
content: Probably something wrong with a thin a pin in the center. IIRC it is for charger power detection. Could be damaged pin or broken wire in the cable.

author: wraper
author_rank: Unknown
timestamp: September 03, 2015, 11:14:40 pm
content: Probably there was just a resistor to GND, measure resistance to GND on working one and compare with faulty one. Google about it too. Usually cable gets damaged within a few centimeters from the power brick or near the connector where most of the bending happens. You could crack open the brick, check the wires in the cable. If faulty, cut 10-15 cm of cable and check again. If it measures OK, solder the cable to the PCB and glue the brick back into one piece.

author: samnmax
author_rank: Regular Contributor
timestamp: September 04, 2015, 08:35:23 am
content: Once I got an HP dv series laptop that would sometimes refuse to charge the battery, even with an original charger. Believe it or not, I removed the internal third pin connection (took the wire from the connector on the PCB) and everything was fine and dandy.

author: andybarrett1
author_rank: Regular Contributor
timestamp: September 04, 2015, 08:21:05 pm
content: Quote from: wraper on September 03, 2015, 11:14:40 pmOr "Brick" depending on your veiwpoint !!!

author: wraper
author_rank: Unknown
timestamp: September 05, 2015, 07:05:45 am
content: Quote from: andybarrett1 on September 04, 2015, 08:21:05 pm, hilarious typo.
Garmin GPSmap278 (276c) - Page 1
Forum section: electronics / repair

author: TonP
author_rank: Newbie
timestamp: September 04, 2015, 11:04:05 am
content: The screen of my Garmin have some problems. i fond out that somebody ruin the displayconnector inside the unit.Tried some repair but...Garmin and other repair shops can't help me. To old, no parts anymore. So, i defenitly need a new connector to make the flatflex connected to the PCB. Could'n find a solution at the moment.Who can help me?

author: mcinque
author_rank: Unknown
timestamp: September 04, 2015, 11:34:26 am
content: Maybe some pictures of both sides of the connector can help, I guess someone can recognize the part that you need

author: TonP
author_rank: Newbie
timestamp: September 04, 2015, 05:44:07 pm
content: Some picsStamp in: JAE (other side) GPrinted on connector: 73156Q
Fixing a matrix lcd with faded/missing elements - Page 1
Forum section: electronics / repair

author: dexters_lab
author_rank: Unknown
timestamp: September 04, 2015, 08:47:54 am
content: I have a dot-matrix lcd here off what some might call a vintage kurzweil k2500x musical keyboard (dates from 1995), the lcd has missing horizontal lines and is also faded in the centre vertical section... it is also pretty hard to read generallyjust wanted to ask before i take the lcd screen out and start trying to reseat the zebra strips etc if there is anything else i can do to help it improve?I am sure i recall some someone here improved a dmm (was maybe a Fluke?) that had similar issues but i cant seem to find the thread

author: amyk
author_rank: Super Contributor
timestamp: September 04, 2015, 12:05:18 pm
content: Cleaning the zebra strips would be the first thing I'd try.It could be a rather standard display module/controller, so finding a replacement might not be as difficult as you think.

author: Deathwish
author_rank: Unknown
timestamp: September 04, 2015, 12:10:20 pm
content: I'm with Amyk, i had the same on my fluke 25 till i cleaned up the connecting strips with IPA

author: dexters_lab
author_rank: Unknown
timestamp: September 04, 2015, 12:19:05 pm
content: thanks, it is a standard module thankfully... well at least from an electrical POV, i looked into it a while ago and found some that would fit with some modification of the bezel and sometimes you see direct replacements on ebay but i would rather not have to spend money on it at the moment.will clean/reposition the zebras and see how it goes
HP 37717C fan location - Page 1
Forum section: electronics / repair

author: Srbel
author_rank: Frequent Contributor
timestamp: September 04, 2015, 09:17:38 am
content: At work, we have an HP 37717C that is overheating. It gets so hot after 15 minutes of operation that plastic begins to smell, and the chassis is very hot. Otherwise, it is functional.They say that cooling fan is gone. But the problem is that there does not appear to be any fan or fan location on the outside of the unit. There are just vent holes.I have looked at some fotos from the internet, and they all look the same, no fan. So, the only possibility is that the fan is in the inside of the unit, but I can not find any information on it. None of documentation for HP 37717C mentions anything about fan.So, does anyone knows something about it?P.S. I can not open it up without permission, so I would need some evidence of the location/existence of the fan. I mean, if it was mine, I would just opened it up, but...

author: jitter
author_rank: Frequent Contributor
timestamp: September 04, 2015, 04:42:52 pm
content: I may have worked with one of these a very long time ago ("OmniBER" definitely rings a bell), but I couldn't tell from experience where the fan is.My assumption is that there is a fan inside since there are no vent holes on the top. Devices that produce a fair amount of heat but rely solely on convection would need holes on the top and the bottom.Based on photos my guess is that the fan is at the rear left and the air exits from the left side.Time to ask for permission. No point in overheating and destroying something this expensive because of just a failed fan.Edit: typo corrected.

author: mikerj
author_rank: Super Contributor
timestamp: September 04, 2015, 06:29:27 pm
content: I just nipped down to the lab to have a look at out OmniBER but it's a newer unit and there's no mistaking the five fans on the rear of it! It also has the worst user interface of any HP/Agilent kit I have ever used.I would certainly expect an instrument of this vintage with a CRT to have a cooling fan anyway.

author: Srbel
author_rank: Frequent Contributor
timestamp: September 04, 2015, 06:38:20 pm
content: Yes, we also have couple of newer OmniBER models (with Agilent badge), and they indeed have a fan on the back. But on this model, it is buried somewhere inside, and I don't think that it is easy to open. It i supposed to slide out, or something, but it seems that some plastic caps on optical connectors will get in the way, and I feel that they will brake if I try to take them off.I will see next week, but we are very busy at the moment.P.S. The instrument just sits there unused.. Sometimes, colleagues (including me) would take it and use it, only to find out that it is overheating. So, that is why I would like to fix it.
TTI TG330 No Amplitude Adjustment - Page 1
Forum section: electronics / repair

author: andybarrett1
author_rank: Regular Contributor
timestamp: August 31, 2015, 08:26:28 am
content: Hi AllJust got my trusty TG330 of the shelf to do a few tests…. And discovered the O/P is stuck at 7.6V no amount of winding the Amplitude control will budge it….. Yes, at this moment in time it is open circuit (No Load) but I would expect some movement.The display is indicitive of movement (swings 0-21.5v) out but this not replicated on the Output Jacks.Haven't opened it up yet to look see, but wondered if anybody here had experience of similar issues.Maybe I not driving it right…. Open to suggestion. The rest of the FG works as is should.Thank you for looking !Andy

author: andybarrett1
author_rank: Regular Contributor
timestamp: September 01, 2015, 03:08:10 pm
content: Just opened it up.... Had a look round.Whilst on bench started working !!Usual tapping. Throwing switches etc..... and still works.Put back together and still working... !!I have now got the service manual if anyone interested. Thank you TTI !
RTL-SDR Upgrade, lost a cap.... then lost another one. Im not sure what it does? - Page 1
Forum section: electronics / repair

author: rwgast_lowlevellogicdesin
author_rank: Frequent Contributor
timestamp: July 31, 2015, 03:41:44 am
content: Ok so I measured the cap at 280uF before it popped out of my tweezers, there is a weird design on the RTL board im not sure if its an underpopulated component or what, or some kind of pcb rf voodoo! The cap im missing is connected to this strange pattern then ground. The cap is labelled c50 in the picture. So can I slap anything in there? Or is this some kind of filter or something? Ive circled where the cap was and traced it so its easier on to understand

author: tautech
author_rank: Super Contributor
timestamp: July 31, 2015, 01:43:03 pm
content: What's the device on the left? IC?Can you identify C50's function by its pinout?

author: frahul
author_rank: Contributor
timestamp: July 31, 2015, 01:54:28 pm
content: The device to the left is a USB connector.

author: tautech
author_rank: Super Contributor
timestamp: July 31, 2015, 02:14:48 pm
content: Then if C50 is between V+ and Gnd, you won't go wrong with .01 or .1 uF.

author: KD0CAC John
author_rank: Frequent Contributor
timestamp: July 31, 2015, 02:19:09 pm
content: I looked at mine and noticed at least one unpopulated spot also .My guess is that there is multiple versions using the same board ?

author: rwgast_lowlevellogicdesin
author_rank: Frequent Contributor
timestamp: August 03, 2015, 04:04:30 pm
content: Ya I figured out it was an extra input cap for the 3.3v regulator, which im tearing out anyways... so no biggie. Im just curious if that underpopulated set of pads has the potential to radiate EMI/RF? Im trying to cut all the pieces off this board that are unneeded for SDR functionality the build an enclosure out of copper clad for it.

author: Lord of nothing
author_rank: Super Contributor
timestamp: August 30, 2015, 10:38:08 pm
content: Does anyone use it here?I know there are many forum about that but hey....

author: rwgast_lowlevellogicdesin
author_rank: Frequent Contributor
timestamp: August 30, 2015, 11:59:10 pm
content: Does anyone use what RTL dongles? I do lol... I just got a new r80t2 version im modifying, Im hoping to use a huge dish to get the voyager 1 downlink. Longest DX ever!

author: Lord of nothing
author_rank: Super Contributor
timestamp: August 31, 2015, 01:30:30 am
content: Where are you from?

author: Dave
author_rank: Super Contributor
timestamp: August 31, 2015, 01:51:39 am
content: That definitely wasn't a 280uF capacitor, more likely a 280nF one.You can put any 270nF cap in its place.I'd say those unpopulated components next to it are a buck converter. You have a regulator chip, an inductor, two resistors and a capacitor. The output capacitor must be on the other side of the board, where that large via leads. No RF voodoo there.

author: Lord of nothing
author_rank: Super Contributor
timestamp: August 31, 2015, 01:54:32 am
content: Why does nobody build a SDR with 5 of thoes dongle at one PCB and use 1 or 2 Signal Imput?!That would be buch more handy on Public Transport on a Aircraft.
Webcam IR Mod failed.... - Page 1
Forum section: electronics / repair

author: Lord of nothing
author_rank: Super Contributor
timestamp: August 30, 2015, 09:52:36 pm
content: Hey...I try to mod 3 Logitech Webcams and failed... Super Glue isnt a good idea with plastic lense....The next idea is an extream cheap chinese airsoft scope for that lese.What i want is an IR only Webcam "longrange" licence plate scanner.In the future maybe an visible aircraft tracking.Thanks!
Toroidal mains transformer winding repair - Page 1
Forum section: electronics / repair

author: Chris Wilson
author_rank: Super Contributor
timestamp: September 10, 2015, 09:46:56 pm
content: I have a 240 V primary, centre tapped 35V 0 35V at 8.6 amps (600VA) toroidal transformer that someone has shorted primary to secondary by carelessly drilling a hole in the equipments cabinet and putting a self tapping screw into the winding. (I wonder who this idiot could be? Me? Surely not....Even worse, not realising, I applied mains to it... It had a fuse in the primary though, and damage appears very localised.I have removed the secondary as it's only about 60 turns. Once I un-tape the primary is it viable to remove a turn or two to get rid of the damaged enamelled wire, which seems to be two or three turns only, carefully fit Raychem heat shrink and solder? The alternative is taking off a huge length of wire. Output voltage is not that critical. Thanks.

author: retrolefty
author_rank: Super Contributor
timestamp: September 11, 2015, 12:25:09 am
content: Should work.

author: Stray Electron
author_rank: Super Contributor
timestamp: September 11, 2015, 03:11:16 am
content: You should also be able to remove a proportional number of turns on the secondary and keep the correct output voltage if you like.
Sansui SLED2237 - Page 1
Forum section: electronics / repair

author: Aspiringloser
author_rank: Newbie
timestamp: August 30, 2015, 12:33:42 am
content: Hello all,I'm trying to find a service/repair manual or schematic for a Sansui SLED2237. So far I can only find an owner's manual. Any suggestions?Thanks in advance,Paul.
APC BP1000, missing front panel - Page 1
Forum section: electronics / repair

author: Scrufdog
author_rank: Newbie
timestamp: August 25, 2015, 07:07:52 pm
content: Hey everyone. Found you on YouTube. Watched episode 504, tear down of an APC 2200 UPS. Figured this would be the best place to ask a question.I came across an APC Back Ups 1000 Pro (BP1000) with dead batteries, and missing the panel switch/LED panel. I dropped in a couple batteries and plugged it in. Single beep, couple clicks, and a hum of the charger, charging properly. Checked various voltages here and there and everything seems ready to try. However, without the front panel, no on/off switch...I have 118vAC up the main relay that turns on the outlets. I can't find any schematics for this unit, but the couple I have found for other models with a ribbon cable, make me think of the 8 pins, one of them is looking for a momentary GND signal to turn on. Before I just poking pins with GND, any recommendations for me? I figure if need be I'll build the serial control cable for it and try turning it on with my laptop.Here's what I have found on the ribbon cable...Pin 4 - GNDPin 5 - 4.4vDCPin 9 - 4.9 vDCThanks for any help you can offer.

author: Scrufdog
author_rank: Newbie
timestamp: August 27, 2015, 12:36:47 am
content: Update, to fix my mistakes and update what I've foundReferencehttp://eevblog.com/files/apc_smart-ups_su2200_3000.pdffor the schematic I'm looking at.So it turns out the SU2200 (which I got the schematic for) has very similar circuitry as the BP1000, down to many of the component labels and numbers.I found that I can tap jump ground to the J11A Pin 6 (labeled as the On switch on the SU2200), I get a short beep and 10 seconds later relays start clicking, and I hear the inverter turn on. The voltage at the main output before Relay 1, goes from house 120 to 230v, and holds there for about 5 seconds. Not sure if this is a diagnostics test, since I cant see what the front panel might be doing, and I've never had a UPS that had a built in diagnostics mode. At no point can I get the main relay to pass voltage to the outlets. I've checked both sides of the relay's coil and both sides are always 24vDC. One side is connected to 24vDC supply, and the other to a series of switching transistors and the main control IC. From what I can gather after clearing my brain of the dust on my electronics knowledge, the circuit should pass ground to the 'negative' side of the coil, unless 'commanded' by the IC to shutdown. I'm getting a constant 4.0vDC from pin 25 of IC12 and 0.5vDC on the base of Q45. 24vDC on the collector and GND on the emiiter, of Q45. Q44 base and collector are 24vDC and the emitter is GND. If I'm thinking right, the base of Q45 needs to go high (24vDC) to pass ground to the base of Q44, thereby passing ground to the 'negative' side of the relay. Pardon me if I'm wrong, its been 20 years since I took Electronics Engineering. Assuming this is true, I'd say that IC12 isnt putting out the turn on signal for whatever reason, possibly because it cant talk to the board on the missing front panel.Anyone care to take a look and offer advice?Thanks
Magellan SL barcode reader - Page 1
Forum section: electronics / repair

author: bugy
author_rank: Newbie
timestamp: August 29, 2015, 04:55:39 pm
content: I need to connect PSU to this thing, but problem is I don't now pinout of connector and I can't find manual for it.So I tried to open it and find parts that use certain voltages so I can use continuity tester to determine pinout . But it seems to be very difficult to disassemble so I got access only to one side of boards, where are only to ICs. One have heat sink soldered to board and i can't see part number, other is this thingAcording to Google it is quadruple 2-input NAND gate. Problem is that in datasheet pinout is given only for trough hole (and FK) version of it. Is pinout same for SMD version?Is it usual for brown wire to be ground? Because according to some silkscreen labels GND is brown and blue I think!?BTW, if anyone have repair manual for this machine feel free to share.Model number:Specifications:ConnectorsPower connector
Uknown function JFET  OS7020 GOLDSTAR - Page 1
Forum section: electronics / repair

author: vodka
author_rank: Frequent Contributor
timestamp: August 26, 2015, 05:42:04 am
content: hello ,Which is the function from the JFET transistor Q202?

author: c4757p
author_rank: Super Contributor
timestamp: August 26, 2015, 05:44:40 am
content: It's being used as a diode. If you don't need high reverse voltage or high forward current, they make very nice ultra low leakage diodes.

author: vodka
author_rank: Frequent Contributor
timestamp: August 26, 2015, 08:00:25 pm
content: thanks
Testing Digitech Bass Modeler Pedal - Page 1
Forum section: electronics / repair

author: ricardohd91
author_rank: Newbie
timestamp: August 26, 2015, 05:21:19 pm
content: Hello, I came across a Digitech Bass guitar digital effects pedal but it's not turning on. It runs off 9 volts and I've been testing it with a multimeter. I don't have a scope, so multi meter is my only avalible tool. It uses 6 AA batteries, but for diagnosis sake I soldered a 9 volt battery connector to the battery pos and Neg pads to test outside of the case. Voltage is 8.67 on the battery, not new. It supposedly turns on when a guitar is connected. I placed the multi in series in amp mode and I get .02 with the input cable disconnected and jumps to 2.89 when I plug in the cable. Does that seem to high to anyone? First attachment is the component side, second is the solder side. Third and fourth are the input jack, that is what turns on the circuit.It cost me 3 dollars at a flea market and online it goes for 35 to 75 depending on condition. If I can get it going that would be great.

author: ricardohd91
author_rank: Newbie
timestamp: August 26, 2015, 05:48:56 pm
content: I got in contact with the manufacturer and managed to get the schematics. its attached.
Leaky batteries - Page 1
Forum section: electronics / repair

author: Fungus
author_rank: Super Contributor
timestamp: August 25, 2015, 04:54:39 pm
content: What's the best way to clean up the springs in a battery compartment if a battery has leaked a bit and corroded them?

author: SeanB
author_rank: Super Contributor
timestamp: August 25, 2015, 06:37:03 pm
content: NiCd or NimH cells use vinegar. Other alkaline cells as well, followed by a rinse with a paste of baking soda and a final few water washes while scrubbing with a nylon brush. Finally with bare metal use a light coat of grease, baseline or siliconer grease, to keep the bare metal from corroding further.

author: Daniel_Reyes
author_rank: Regular Contributor
timestamp: August 25, 2015, 08:33:54 pm
content: Pee on it.Sent from my SM-G900P using Tapatalk

author: tautech
author_rank: Super Contributor
timestamp: August 26, 2015, 09:15:15 am
content: If you can dismantle it, hot water will dissolve most of the salts deposited as a result of the corrosion and for just the contacts, boiling water. Then as Sean describes Baking Soda is a good neautraliser.Sometimes I will tin contacts with solder to help prevent further oxidisation, but if the contact tension is weak it pays to rework the contacts for trouble free operation.

author: Fungus
author_rank: Super Contributor
timestamp: August 26, 2015, 12:03:43 pm
content: Will try the suggestions, thanks.(Taking it apart first definitely seems to be the way to go.)
Blown PicKit 3/Schematic/What part is this - Page 1
Forum section: electronics / repair

author: BurnedResistor
author_rank: Regular Contributor
timestamp: September 06, 2015, 03:01:12 pm
content: Hey all,Managed to blow my pickit 3 by forgetting to dial my PSU back down to 5V... After some inspection it only seems that one small sot6 part (labeled U9) close to the header is blown.In an effort to repair the dang thing - does anybody have the schematic for the pickit3? Or is anybody willing to open up their pickit3 and tell me what part this is?Any other ideas of what I could do?Sorry for the stupid question!Here is a picture of an intact PCB of the internet with the part circled, will upload an image of the blown as soon as my phone is charged!

author: deephaven
author_rank: Frequent Contributor
timestamp: September 06, 2015, 03:06:12 pm
content: http://ww1.microchip.com/downloads/en/DeviceDoc/52116A.pdf

author: BurnedResistor
author_rank: Regular Contributor
timestamp: September 06, 2015, 03:11:43 pm
content: Thanks!It was the 74LVC1T45!

author: deephaven
author_rank: Frequent Contributor
timestamp: September 06, 2015, 03:28:30 pm
content: Quote from: BurnedResistor on September 06, 2015, 03:11:43 pmPerhaps you need to change your user name

author: SeanB
author_rank: Super Contributor
timestamp: September 06, 2015, 03:55:40 pm
content: Well, it is burned, and now is a resistor...........
LED display issues - Page 1
Forum section: electronics / repair

author: HinesNetwork
author_rank: Contributor
timestamp: August 24, 2015, 06:14:58 pm
content: Hi all,I'm hoping someone can point me in the right direction. My Whirlpool ovens display is going out. I thought it was the LED's actually failing but I removed the board and tested them and they work. When I put the board back in the oven the display started working again. However it started failing again (not sure of the actual time, but maybe an hour). I can only assume that disconnecting the power caused the microcontroller to reset. Does this mean the microcontroller is diving? Or is there something else I should be looking at?Thanks,Jason

author: Andy Watson
author_rank: Super Contributor
timestamp: August 24, 2015, 08:23:08 pm
content: What test equipment do you have?More information would be useful in making a diagnosis. But, taking a flying guess, I would guess that something is shutting-down due to thermal problems. Could be the display driver but more likely a voltage regulator. If it is the later it could be due to faulty caps across the supply (look for something(s) getting hot), or it could be due to reservoir caps drying out, or it could just be a faulty regulator.

author: HinesNetwork
author_rank: Contributor
timestamp: August 25, 2015, 11:56:04 pm
content: I've got several DMMs, logic analyzer, scope (although I've been afraid to use it on this since it's powered by AC).I suspect it's a thermal issue too. It's just strange that it worked after being disconnected for awhile. I saw no physical indications it was a bad cap. I should have some time to remove it and do some more testing tomorrow.Thanks,Jason
Tektronix TDS 540 CRT screen failing when heated up - video inside - Page 1
Forum section: electronics / repair

author: twobeseen
author_rank: Newbie
timestamp: August 27, 2015, 08:09:56 pm
content: Hi there,I got an old TDS 540 oscilloscope and since yesterday it has a new bug: After heating up for about an hour the screen starts to distort and after few seconds it collapses. The the screen comes up anew just to repeat the same over and over. After a cooling period the oscilloscope works fine for another hour.See here my video:https://youtu.be/Cxavdhe6vHsWhat could be wrong? I searched the internet but nobody describes this crt error.Is it the crt driver board or more likely the crt itself e.g. the high-voltage flyback transformer? Could it be a leaked cap? Anybody out there who is an experienced television repairman? Of course I know it can be dangerous to play with the high voltage...In the end I am considering to replace the crt with an LCD replacement but this will be a lot of work if even possible (I found some information about that).....

author: OldSchoolTechCorner
author_rank: Frequent Contributor
timestamp: August 28, 2015, 05:19:58 am
content: Had fix one that had one where a capacitor leak near the flyback causing a carbon track that cause that same issue. I more suspect leaking caps since common issue with this model and 744a. Also if input current to increase to flyback power supply will to go to protect mode after running for a while. Wonder what the input current of primary side is and temperature of transformer? Could be failing flyback.

author: vk6zgo
author_rank: Super Contributor
timestamp: August 28, 2015, 05:21:51 am
content: Quote from: twobeseen on August 27, 2015, 08:09:56 pmIt won't be the CRT--that is the glass thing!!----only computer folks call the whole thing a CRT!The white highlights still appear when it does its "party trick".If it isa raster display,the problem may be in the "boost HT" circuit----an overwind on the LineOutput transformer is rectified with a fast recovery diode & filtered to give around 160v.This supplies volts to both the horizontal & vertical circuits,as well as the amplifier feeding the CRT cathode.If something is failing there,you may well get the problem seen.Open the thing up while it is still cold,& direct a source of heat at various points around the circuitry associated with the CRT.Alternatively,buy some "canned cold" (freezer spray,& when the fault has already happened,selectively cool around the same area.
HM303-6 service manual needed - Page 1
Forum section: electronics / repair

author: phil
author_rank: Regular Contributor
timestamp: August 20, 2015, 05:36:14 pm
content: Hi,I have a repair request for a HM303-6 scope. However, I could not find any schematics or a service manual. There is a SM for the HM303-5, but there have been huge changes between 303-5 and 303-6.What I know about the scope is that the previous owner forgot to discharge a cap and killed the component tester that way. The X-deflection is damaged, there is no sweep and the beam (now a dot) is shifted to the left by about 5 divs.I could check the X-amp but now I reached the limit of what I can do with the old 303-5 schematics.Does anyone here have schematics for the 303-6?Thanks,phil

author: Simon123
author_rank: Regular Contributor
timestamp: August 20, 2015, 10:38:52 pm
content: There was another thread asking about schematic.Someone mentioned this link in ithttp://www.hameg.com/service_main.0.html?&L=0You could also try contacting Rhode and Schwartz, cause old hameg is now R&S as far as i know.

author: Fraser
author_rank: Super Contributor
timestamp: August 25, 2015, 01:52:49 am
content: Just contact Hameg. They will happily supply the schematic. I have received such on many occasions.Aurora
T-CON board / Which design of capacitors ? - Page 1
Forum section: electronics / repair

author: miette_Kruemelchen
author_rank: Contributor
timestamp: August 23, 2015, 08:12:47 pm
content: Hello,I would like to repair T-CON boards. For industry, the T-CON Board is part of the LED / LCD panel. The repair is often an economic write-off.We find not circuit documents of this TCON boards. :-( We find datasheets of few chips. It is a matter of luck!I want to learn more. In the appendix is an image. This is a T-CON Board of a LG/PHILIPS Panel (type : LC260WX2). The board is defective!On the right side you can see the power supply. Here are produced the voltages VS, VGH, VLOGIC, VGL. I want to measure more on the board. I can’t find datasheet of the processor. It is an LG.Philips LCD TL22710D processor. (OITLL-0011A E316.0632)Where could I find such documents. Have you an idea. A signal paths are very helpful. With practical exercises I want to better understand the T-CON Boards.I have a problem with the power supply on the TCon Board. It are defective capacitors.Here is a datasheet of TPS65160 IC. C3 and C16 are defect.Are the Tantalum SMD capacitors? Which design of capacitors ? What is the polarity?Can you help me. Where can I find more information! Thank you for your help.kind regards,Sven

author: wraper
author_rank: Unknown
timestamp: August 23, 2015, 08:46:11 pm
content: Quote from: miette_Kruemelchen on August 23, 2015, 08:12:47 pmWhy do you think they are defective? I seriously doubt your ability because you even cannot distinguish ceramic capacitors. They don't have polarity.

author: miette_Kruemelchen
author_rank: Contributor
timestamp: August 23, 2015, 09:08:49 pm
content: Hello !Thank you for your answer.I know Ceramic Capacitors! I know that there is no polarity! But there must be a kind of electrolytic capacitors. See image !Bye, Sven

author: acbern
author_rank: Frequent Contributor
timestamp: August 24, 2015, 10:42:10 am
content: why should these two be electrolytic. they are not, electrolytics look different (look at your own picture). again, they are ceramics. and why are they defective, how have you found out?
Agilent E3616A PSU, dead [FIXED] - Page 1
Forum section: electronics / repair

author: HighVoltage
author_rank: Super Contributor
timestamp: August 23, 2015, 12:39:21 pm
content: My Agilent E3616A is from 2007 and suddenly died.After "turn on", the display shows random stuff and nothing happens on the output and OVP light comes on right away.I was looking for the schematics but there is nothing on the Keysight website.It seems like Agilent has pulled service manuals and schematics already in 2007.http://www.keysight.com/main/editorial.jspx?cc=AL&lc=eng&ckey=1000000367:epsg:man&nid=-536902299.384304.00&id=1000000367:epsg:manThere is the operating manual that even says "Service Manual" on the cover page but is has no usable content for repairing this PSU.Does someone here might have a full schematic?Thanks.

author: Deathwish
author_rank: Unknown
timestamp: August 23, 2015, 01:27:41 pm
content: http://elektrotanya.com/hp_agilent_e3614a_e3615a_e3616a_e3617a_sm.pdf/download.html

author: HighVoltage
author_rank: Super Contributor
timestamp: August 23, 2015, 01:34:49 pm
content: Thank you Deatwish,But that one is the same as the one on the keysight website or many others that I foundThe oldest one I found was by HP from 1999 and it also does not include the service manual / schematics.Since this PSU was already made during the HP time, one would think that it is easy to find a good schematics.I will keep looking.

author: HighVoltage
author_rank: Super Contributor
timestamp: August 23, 2015, 01:44:00 pm
content: I found the schematics and parts list here:https://github.com/ee-lco/e361xa/blob/master/doc/AgilentE361516AManual.pdf?raw=trueThe schematics was annotated by someone but it is ok to use.Now the trouble shooting will begin.

author: HighVoltage
author_rank: Super Contributor
timestamp: August 23, 2015, 02:00:01 pm
content: OK, I found a big problem on the railsU13 is a LM317 and is suppose to be at +15VMeasured 1.2 VoltsU14 is a 7912 and shows no output at allThe input from the transformer seems to be OK.So, I will exchange those two regulators and see what happens...

author: SeanB
author_rank: Super Contributor
timestamp: August 23, 2015, 02:22:24 pm
content: With them out check the input voltages to the regulators and if there is not a short on the output. Strange that both rails go at the same time, I would suspect the output has a short somewhere, or R108 has gone open.

author: HighVoltage
author_rank: Super Contributor
timestamp: August 23, 2015, 03:56:39 pm
content: @SeanBThanks for the feedback.R108 was OKNo shortage on the outputs.All capacitors OK and both diodes (CR31, CR32) are OKI installed two new regulators and the PSU works perfectly!Almost too god to be true and a big surprise, but even the calibration is spot on.To the failure:Yesterday I used the Agilent PSU to supply 12V at 500 mA to a cascading high voltage DC supply.I think some high voltage spikes must have traveled back to the Agilent PSU.So, bottom line... 2 new regulators and couple hours of work and the power supply works like new.

author: BFX
author_rank: Frequent Contributor
timestamp: August 23, 2015, 11:34:04 pm
content: Good jobZum Wohl! :beer:
Trying to source some spring loaded binding posts. - Page 1
Forum section: electronics / repair

author: jmcdonald
author_rank: Contributor
timestamp: August 23, 2015, 09:51:34 am
content: Trying to source some spring loaded binding posts the same ones that are used on the Fire One Pyrotechnics system. looked online for hours

author: German_EE
author_rank: Super Contributor
timestamp: August 23, 2015, 04:13:53 pm
content: You're right, they are difficult to find, an interesting diversion whilst the girlfriend is watching 'Die Wunderbare Welt Der Tierbabys' on TV.

author: sunnyhighway
author_rank: Frequent Contributor
timestamp: August 23, 2015, 05:19:42 pm
content: They are calledTall PyroClipFound 2 suppliers:http://pyromagicinc.com/pdf/pyromagicinc-current-catalog.pdfhttp://www.greatwallpyro.com/T_ProductShow.asp?ProductID=69&SmallClassID=81&BigClassID=29

author: German_EE
author_rank: Super Contributor
timestamp: August 23, 2015, 05:51:12 pm
content: OK, thank you for the link, I have just ordered eight of them in various colors for my workshop power supply.

author: jmcdonald
author_rank: Contributor
timestamp: August 23, 2015, 10:07:28 pm
content: Quote from: sunnyhighway on August 23, 2015, 05:19:42 pmThanks for the help
old amp starts to fail, but not sure wat.  - Page 1
Forum section: electronics / repair

author: milanhofman
author_rank: Newbie
timestamp: August 23, 2015, 10:11:54 am
content: hi there,i have a few old amps (stage accompany two 900C's and one 500C)these amps are baslicy tow mono amps in one case, separate power supply and everythingthe system is actively filtert, (an amp on eatch driver directly)now for the fun part,THE PROBLEM:sometimes i turn the system on, and then after 10 or 20 seconds one side of one amp goes TICK!(i believe full power)the signal led does come on, (no protect or overload leds)usually ones, sometimes twice. other times no TICK at all..even less often the same side of the amp's signal led comes on and stays on until i give it a "technical tap"(whack it on the face of the amp)usually its gone then, but sometimes when the signal led goes on by means of signal being pressend it stays on even if i mute the audio, "technical tap" it again and it goes away,last time i measured there was no DC on output, (or AC)somehow this sounds like an op-amp to meall the other amps/sides are just fine,i don't have mutch equipment, only a basic multimeter and a fixed 13.8 volt powersuplyany suggestions about what it may be?thanks for your time and helpMilan Hofman

author: DrGeoff
author_rank: Frequent Contributor
timestamp: August 23, 2015, 10:33:34 am
content: Check all the solder joints first. Resolder any that look suspect.Often in older equpment (particularly if it has been roaded) the solder joints can go cold or brittle, and lead to symptoms similar to what you describe.

author: milanhofman
author_rank: Newbie
timestamp: August 23, 2015, 01:47:51 pm
content: it has not rely bin on the road, but still not a bad startwhat else could fail in a amplifier like this?

author: retrolefty
author_rank: Super Contributor
timestamp: August 23, 2015, 07:29:04 pm
content: QuoteThat sounds like a logical leap of faith with no foundation. A technical tap is not a very valuable troubleshooting method other then saying you have something intermittent or thermo going on. What it is will have to take more precise troubleshooting steps.

author: DrGeoff
author_rank: Frequent Contributor
timestamp: August 23, 2015, 09:21:19 pm
content: Quote from: milanhofman on August 23, 2015, 01:47:51 pmConnector corroded or wire termination intermittent. That includes any sockets used for IC's.Assuming that you have already checked the obvious things like PSU rail presence and stability.
Acer Iconia 6120 Bottom Touch Screen Ghost Touch on onsreen Keyboard - Page 1
Forum section: electronics / repair

author: ananthad
author_rank: Newbie
timestamp: August 22, 2015, 02:44:59 pm
content: Hi I bought a Acer ICONIA 6120 Dual Touch Screen Laptop in 2011 when I was in US. I returned to India in 2011. In 2014 the bottom touch screen virtual key board started mal-functioning. The keys will automatically click making it unable to use. I gave it to a local technician he disabled the bottom touch screen. He also said the Hard Drive is corrupted needs replacement. He replaced with a new 500GB hard drive. While replacing it he changed the Windows 7 home premium to Windows 7 ultimate. From then on we were using it with a wireless key board. Now I am trying to repair the laptop. 1) Where can get 14" bottom touch screen so that I can buy and install 2) Where can get the recovery disks along with windows 7 home premium Thanks in advance for your help
[help]macbook pro power on itself! not charging! - Page 1
Forum section: electronics / repair

author: phantom
author_rank: Contributor
timestamp: August 22, 2015, 09:16:54 am
content: hi to all, i'm ruben from italy. i'm not good with electronics, so i hope you can help me to fix my unique macbook pro payed a lot of moneythe macbook pro is model a1278 i7. motherboard 820-2936-aa) it says "battery not charging" 61%b) if i disconnect the power supply, it power offc) with only the battery, it doesn't power ond) when i connect the power supply (with or without the battery), it power on itselfe) the led of the power supply is always greenf) i have 5/8 led on the battery only if i connect the power supplyg) i've try to reset smc. but it doesn't work (led always green)h) if i hold for then second power button, then i connect the power supply then i release the power button, it power on with fan at max speed, but the battery is not seen anymorei) i've try to do all those thing with the motherboard outside the case and with anythign connected, it doesn't change, i've always the same problem

author: Psi
author_rank: Super Contributor
timestamp: August 22, 2015, 09:22:55 am
content: Is it a genuine Apply battery and Apple power supply? or are any aftermarket?

author: SL4P
author_rank: Super Contributor
timestamp: August 22, 2015, 12:16:51 pm
content: Can you swap in a similar battery from someone's else's Mac?That will allow you to isolate the battery and its internals as the problem.The symptoms sound like the charger circuit is working, and the computer will run from that, but as soon as you remove the external AC /charger source - the battery is 'not there' !!

author: phantom
author_rank: Contributor
timestamp: August 22, 2015, 12:36:51 pm
content: yes you are right! in another forum some says me"i5-i7 model power on themself if battery not connected."so the best should be to find another battery and try!
Induction motor- faulty or not? - Page 1
Forum section: electronics / repair

author: BurningTantalum
author_rank: Frequent Contributor
timestamp: August 22, 2015, 05:19:47 am
content: I scored an 1970s 'made in Taiwan' bench grinder from the dump. It had a shattered Bakelite mains switch and the wires had been disconnected.I wanted it for mounting a pair of small polishing mops.The armature has a centrifugal switch and may not have had a start capacitor as there is no evidence of mounting.The windings have two red wires and two smaller white wires. I tested for continuity which seemed OK, but found one red is short to one white. I removed the windings from the frame and could see that the red and white are crimped into a sleeve in the varnish. Close inspection revealed that only one copper wire went from this sleeve into the winding, but elsewhere there is a single copper wire from the slots into a sleeve and two copper wires out into the slots.Red to red measures 13R 48mH.White to white 12R 25mH. Then I measured red to white (not the shorted ones) and found 12R 25mH. This suggests a third winding.I'm confused and cannot see how to connect this to run it. The windings are very clean with no discolouration or damage.Any ideas welcome, BT

author: tautech
author_rank: Super Contributor
timestamp: August 22, 2015, 05:48:53 am
content: Small bench grinder motors commonly do not have start or run caps.One winding is as you have probably guessed a run winding and the other start with the centrifugal switch dropping the connection to the start winding when appropriate RPM is reached.A bit of Googleing should find schematics.Check the makers label for watts or current and when you have it running check current draw is in the right ballpark.

author: BurningTantalum
author_rank: Frequent Contributor
timestamp: August 22, 2015, 07:09:39 am
content: Thanks,that was the expected configuration, but what I don't understand is why if I test resistance between the red and the white leads (with other red/white shorted together) I don't read the sum of the two winding resistances.BT
Canon SD780IS from eBay repair story - Page 1
Forum section: electronics / repair

author: edy
author_rank: Super Contributor
timestamp: August 25, 2015, 01:22:47 pm
content: Hi folks,Just a quick report. I was meaning to ask here first but it turned out to be easier than I thought and fixed it. So I'll share what happened in case anyone else has the problem.I searched for a backup to my regular work camera (Canon SD780IS). It is an old camera but well constructed with metal casing (now they are all plastic). Because my photos are all standardized I needed the same model, and they are all over eBay. Usually a working camera gets bid up to $50-60 once shipping is included, which is high considering the age of this model.Anyways, someone was selling it for $12.99 (with $4.99 shipping) in Canada so it sounded attractive. Only problem is the SD CARD reader complains the card is locked and can't save any photos. Sounded to me like a jammed pin in the card reader slot, so I took a chance and bought it.I tried the usual toothpick and compressed air trick, putting tape over the write-protect tab of the SD card, etc. Nothing worked. Finally I decided to take apart the camera. 5 screws around the side and bottom and I'm in like Flynn. Both metal back and front shell casings pry apart. Now the PCB with the card slot is covered by at least 6 or 7 flat flex cables, many press fit into slots, others slide into sockets that have a plastic locking mechanism. I carefully disengaged all flat flex cables. There was also a copper shield/heat sink stuck to one of the microchips which I needed to peel off. Finally accessed 3 more screws holding the PCB and after removal, got the whole board out.On the other side of the board was the card slot and now I could clearly see the pin that was damaged. Turns out the contact needed to be CLOSED to indicate card is writable. If contact was open, it thinks the card is write protected. So the contact is made of a stationary flat metal tab, and just beside it is a flexible tab that gets pushed against it by the card when you slide it in. If the plastic tab on the card is in the "write" position, it presses the flexible metal contact on against the stationary pin and closes the circuit. In my camera somehow the stationary part of this switch got bend 90-degrees over so there was no way in hell it would ever close. Maybe whoever had the camera pushed it.over with a toothpick or I screwed it up.So I bent the contacts back to where they belonged and closed everything up again and it worked!!!

author: edy
author_rank: Super Contributor
timestamp: August 25, 2015, 01:38:34 pm
content: These are not my photos but just to show you the flat flex cables running to the board I needed to completely remove to access the SD card reader (mounted on the flipside). The one in the photo is already missing a few as you can see unoccupied flat flex slots.
Fanac Graphics Board - Page 1
Forum section: electronics / repair

author: Swoop4Formula
author_rank: Newbie
timestamp: August 21, 2015, 11:43:52 pm
content: Hello i am repairing a Wire EDM that used a Fanac A20B-1000-0480-04A board. A few components the look like Tantalum caps have been broken off the board. I would really like to repair with the same style. Does anyone have more info on the type or where i could get a hold of some.Thanks
Rigol DS1052E White screen but not dead - Page 1
Forum section: electronics / repair

author: framil
author_rank: Newbie
timestamp: August 19, 2015, 08:59:43 pm
content: Switched my DS1052E scope on one day to be met with blank (white) screen.It had been working fine, I have had it from new; no 100Mhz hacks or firmware upgrades.Buttons and lights seemed to be working, so I connected the scope to my PC via USB and launched Ultrascope.The Ultrascope Virtual Panel shows the scope display as normal! I can control the scope from the Virtual Paneland see channel input waveforms as expected.So, I have a scope that "works", but has a permanent white screen. Before I start disassembling the device,does anyone have some advice on what the cause might be?Regards,

author: tautech
author_rank: Super Contributor
timestamp: August 19, 2015, 09:23:27 pm
content: Quote from: framil on August 19, 2015, 08:59:43 pmWelcome to the forum.Carefully check the ribbon cable that connects the MB to the display at each end.It will likely involve almost full disassembly of the scope.

author: OldSchoolTechCorner
author_rank: Frequent Contributor
timestamp: August 19, 2015, 09:31:20 pm
content: More likely ribbon on LCD panel, as last comment stated, or bad panel, or controller. Can be fixed more likely.

author: framil
author_rank: Newbie
timestamp: August 20, 2015, 08:01:55 pm
content: Thanks for your replies. I'll get some torx screwdrivers and get inside. Out of warranty - nothing to lose.