hybridfree/eevblog-posts huggingface dataset:
HP 59309A Digital Clock Repair - Page 1
Forum section: electronics / repair

author: morrone
author_rank: Unknown
timestamp: July 21, 2014, 05:44:52 am
content: I picked up an HP 59309A that wasn't displaying the time correctly. Turning it on, it looked to me like the display was changing every second, and the digit transitions happen at the correct time. However, all of the digits were displaying the wrong pattern on the seven segment leds, and all with the same incorrect pattern for the same number.I verified that the time logic is all working correctly internally through the HPIB port using a GPIBUSB.I took the BCD-to-seven segment IC out of the display board and checked it on a bread board. Nope, that it working correctly. Then I checked the hex inverter IC that feeds the four BCD lines to the BCD converter IC. Bingo! Two of the inverters in the IC are bad.So now I have the display fixed. Yay!I also cleaned off the stickers.The top of the metal front piece was corroded, with these lifted bubbles of corrosion. I descided to sand that down. The texture doesn't match the sides, but nice clean sanded metal is a vast improvement.There is only one problem remaining: it is missing the piece of plastic that overlays the LED display section. Perhaps it was glass...I don't know. See this image on hpmuseum.net:Can anyone recommend a material to use to replace it? It would be wonderful to recreate the lettering, but I would also be fine with just finding a piece of plastic that is a reasonable color that I can cut to size.

author: miguelvp
author_rank: Super Contributor
timestamp: July 21, 2014, 06:14:15 am
content: Found some images that might help:some other images here:http://www.leapsecond.com/museum/hp59309a/
HP 34401a Self Test Fail - Page 1
Forum section: electronics / repair

author: lkmurdoch
author_rank: Newbie
timestamp: July 10, 2014, 07:23:36 pm
content: Hi everyone,My first post so here goes.....I have a HP 34401a that fails self test. It does measure AC volts, DC volts reasonably accurately (very close to a Fluke 45) but Ohms is way off cal.The Ohms function measure 00.000 when the leads are shorted, but nothing else. I have checked for signs of obvious damage internally and checked thepower supply voltages which are fine. Any suggestions gentlemen?Thanks in advance,Mike

author: free_electron
author_rank: Super Contributor
timestamp: July 10, 2014, 09:52:11 pm
content: error code ?

author: Dr. Frank
author_rank: Super Contributor
timestamp: July 11, 2014, 06:59:18 am
content: Hi and welcome..not possible to figure out. I suggest you give more detailed hints:- do you run the self test, and then you get an error?- error code available?- what does the instrument read in the different Ohm ranges, each 2W and 4W, with shorted leads and with resistors of appropriate value attached?- did you check the same on the rear connectors?Frank

author: tszaboo
author_rank: Super Contributor
timestamp: July 11, 2014, 08:15:42 am
content: Download service manual from Agilent. Check for your error code in that.

author: lkmurdoch
author_rank: Newbie
timestamp: July 14, 2014, 04:09:38 pm
content: Hello all,No error code was displayed after the self test.I checked the Ohms current source opamp (U201) for correct supply and reference voltages and they are correct.Interestingly on a whim I checked for a voltage on the test leads of any kind and the is none.....the Fluke 45 on the bench shows 1.56 volts DC.Therefore I suspect that there is indeed an issue with the Ohms current source.I would appreciate any insights any of you my have to offer.Michael

author: tszaboo
author_rank: Super Contributor
timestamp: July 14, 2014, 04:58:45 pm
content: On the ohms, there are about a dozen transistor in a weird configuration. They are that way for protection. I would check if they are good.

author: VK5RC
author_rank: Unknown
timestamp: July 17, 2014, 08:33:03 am
content: Front - rear different , 2w 4w different?
Kenwood Trio CS-1040 calibration problem - Page 1
Forum section: electronics / repair

author: Party Scratch
author_rank: Newbie
timestamp: July 15, 2014, 04:34:05 am
content: Hey guys, I am trying to calibrate my oscillosopehttp://u.rpsx.eu/YxW.jpg. I bought the service manualhttp://u.rpsx.eu/QRB.pdfand pretty much following the instructions there. But the problem is, that when I calibrate the vertical CRT centering and the vertical axis positioning and I put the cover back, the traces moves up about one division, the invert position goes off even the trace rotates a bit. How can I solve this? Any ideas? Thanks

author: leppie
author_rank: Frequent Contributor
timestamp: July 15, 2014, 04:49:03 am
content: You should probably not be calibrating it on a carpet

author: Party Scratch
author_rank: Newbie
timestamp: July 15, 2014, 05:19:59 am
content: I am not. I just put it down to show the metal casing, as it wouldnt fit on my table. But how can that make a difference?

author: mij59
author_rank: Frequent Contributor
timestamp: July 15, 2014, 05:36:28 pm
content: Could be a magnetic field.I have got a cs2110.The metal casing is made aluminum, but the handle bar is magnetic.So maybe your handle bar is magnetized.

author: Party Scratch
author_rank: Newbie
timestamp: July 15, 2014, 06:39:52 pm
content: Can confirm, the whole metal casing + handle is made of steel and indeed slightly magnetized. So there is the problem... Thanks. Is there a way to demagnetize it?

author: Party Scratch
author_rank: Newbie
timestamp: July 15, 2014, 08:27:35 pm
content: Hey, I manage to demagnetize it by putting it on top of big ass transformer and slowly moving it up away from it, then I banged it couple times with a wrench and now its demagnetized and it the trace doesn't move even a bit when I put the cover on. Thanks mij59I never thought it could be magnetic field issue I thought there was maybe a shielding problem. Thanks again, now lets get to master my proper tongue angle hehe. Thanks again guys.

author: mij59
author_rank: Frequent Contributor
timestamp: July 16, 2014, 04:17:30 am
content: Quote from: Party Scratch on July 15, 2014, 08:27:35 pmVery nice, great technique !Not only the proper tongue angle, also use the proper breathing technique, breath in , breath out.
Tektronix SG5030 Leveled Sinewave Generator - Page 1
Forum section: electronics / repair

author: lkmurdoch
author_rank: Newbie
timestamp: July 14, 2014, 06:00:09 pm
content: We are considering the purchase of this plug-in a unit….but it shows Front panel Error Codes 81, 82, 83 and 84. A quick review of the service manual, doesn't show what those error codes mean.Help ? Anyone know what these error codes mean ?FYI, this TM5000 Series plug in, is plugged into a TM5006 frame....right beside a CG5001 calibrator....fyi.Any suggestions of a repair center to fix this ?Thanks in advance!Michael
age of hp 6200b power supply - Page 1
Forum section: electronics / repair

author: charles
author_rank: Contributor
timestamp: July 11, 2014, 02:51:19 pm
content: Hello everyone,I am relatively new to electronics and have been trying to repair this hp6200b power supply that I immediately ruined upon purchase.Anyway, I was just curious as to how old the power supply actually is.The service manual is from January 1966, so presumably it is older than that. The serial code on the side is 6j1938, and on the actual circuit board it says hp 5020-5531. The big sprague brand caps say d38618 6730, so presumably the 6730 means 30th week 1967?I have attached a few pictures of the supply. In the end I guess knowing the power supply's age isn't that important but I am just curious.

author: nctnico
author_rank: Super Contributor
timestamp: July 11, 2014, 06:02:57 pm
content: The first digit(s) of an HP serial number is the year. They started from 1960 so your PSU is likely from 1960+6=1966.Those rectifier diodes look quite baked. I'd also replace the electrolytics.

author: amc184
author_rank: Regular Contributor
timestamp: July 12, 2014, 02:01:53 am
content: It's probably from 1967.nctnico is right about the first one or two digits of the serial number being the date, but it's not the date of manufacture, it's the date that the particular revision of the product was first put into production. So this revision of the 6200B was first made in 1966, but your one probably dates from late '67.

author: charles
author_rank: Contributor
timestamp: July 12, 2014, 03:49:36 pm
content: Thank you nctnico and amc184!As to the diodes, what is the best way to test the diodes?I can desolder them and make sure that they are in the <1 volt range (or specifically the number in the diode datasheet if available) in one direction and OL in the other. If the diodes pass this test, does this indicate that they are fine or do I need to check other things?As for the electrolytics, I am hoping to either get a real esr meter or use the oscilloscope/function generator technique.In general, my big problem was originally posted here:https://www.eevblog.com/forum/testgear/hp-6200b-power-supply-blowing-fuses/msg438749/#msg438749Maybe I should start a new thread as I explore?Thanks again.
APC UPS Display Problem - Page 1
Forum section: electronics / repair

author: Homer J Simpson
author_rank: Super Contributor
timestamp: July 09, 2014, 10:25:42 pm
content: I have this APC XS1300 that has developed an odd problem with the LCD I have not seen before. Unit was working fine. All functions work ok.LCD was very bright and viewable from wide angles. Now it is only visible from a sharp angle. It wasn't gradual just one day it started.Have not had a chance to get inside yet to check caps and voltages but wanted to post to see what anyone my think.

author: sparkyresistor
author_rank: Contributor
timestamp: July 11, 2014, 05:45:33 am
content: Sounds like the most possible thing is that somehow something happened to the trimpot they used to calibrate the initial brightness at the factory, but tbh, almost impossible to know without teardown to see how they have it set up.

author: sunnyhighway
author_rank: Frequent Contributor
timestamp: July 12, 2014, 12:04:31 pm
content: Looks like the LCD display could be in power save mode.[see: page 4]http://www.apcmedia.com/salestools/EALN-7SEGRP/EALN-7SEGRP_R6_EN.pdfQuote
Keithley 2015 odd power-up problem - Page 1
Forum section: electronics / repair

author: AndyC_772
author_rank: Super Contributor
timestamp: July 11, 2014, 08:31:27 am
content: Hi all,I bought a Keithley 2015THD a couple of weeks ago. It seemed to be working well.Yesterday I switched it on, but it hung during the boot process. All the display segments towards the left and right sides of the screen were lit, the ones near the centre were off, and after a few seconds I heard a relay clicking on and off quite rapidly (a few Hz). I power cycled the unit and it's not misbehaved again.I'd previously opened it up (shortly after it arrived) and checked inside with a thermal camera, and there was no evidence of anything getting unusually hot - apart from a couple of ICs near the voltage reference, but they're less hot in the 2015 than the equivalent parts in my older 2000.My initial reaction was it's likely to be dead caps in the power supply, but once they're dead I'd expect them to stay that way. I'd also have expected them to be getting noticeably warm when I checked the unit earlier.I guess there's not a lot I can do until the symptoms recur - unless there are any known weak points that result in intermittent failure to boot...?

author: grumpydoc
author_rank: Super Contributor
timestamp: July 11, 2014, 08:46:24 am
content: Part dead caps have certainly caused me intermittent problems in Tektronix psu's. It sounds like the microprocessor didn't reset properly which could easily be a 5V (or whatever) rail ripple issue.
Power supply Oltronix B601D - Page 1
Forum section: electronics / repair

author: Warhawk
author_rank: Frequent Contributor
timestamp: July 10, 2014, 08:31:21 am
content: Hello everyone,I have this PS:http://www.radiomuseum.org/r/oltronix_power_supply_labpac_b601d.htmlwhich was given to me as "broken". Before I start any investigation, don't you have any service manual or schematic ?Thanks in advance !
Help to ID a component - Page 1
Forum section: electronics / repair

author: vivaT
author_rank: Contributor
timestamp: July 08, 2014, 06:09:44 pm
content: I have a microsoft laser mouser 7000 with no power and one chip is getting hot.If you can help ID this chip it would be so helpful as in its place ive been using a tiny mouse which is really hurting my wrist. A replacement 7000 series is around £40 so well worth repairing!The chip is a sot552 package with markings:7ATI AIPIve borrowed another Microsoft laser mouse to look inside, 6000 series, the chip is almost marked the same. The circuits look different as the connected resistors are not values which match.That chip is a sot552 package with markings:56TI AIR

author: amyk
author_rank: Super Contributor
timestamp: July 08, 2014, 09:02:50 pm
content: TPS61010DGS

author: vivaT
author_rank: Contributor
timestamp: July 08, 2014, 11:22:28 pm
content: Many thanks for your effort!
Weird DC Plug Footprint - Page 1
Forum section: electronics / repair

author: fabiodl
author_rank: Frequent Contributor
timestamp: July 12, 2014, 06:25:06 pm
content: I have to replace a faulty DC phi 2.1mm.But instead of having the classic footprint like thishttps://www.circuitsathome.com/products-page/components/dc-barrel-jack-2-1mm-center-pole-diameter,it has the footprint shown in the picture.Has anyone seen something like this?Do you know where I could buy one?

author: amyk
author_rank: Super Contributor
timestamp: July 13, 2014, 02:25:37 pm
content: What product is it from?

author: radhaz
author_rank: Regular Contributor
timestamp: July 13, 2014, 09:24:15 pm
content: Try searching for barrel connectors.

author: fluxcapacitor
author_rank: Frequent Contributor
timestamp: July 13, 2014, 11:48:05 pm
content: do a google search for PCB Mount DC Power Jack.http://www.cablesandconnectors.com/35000-35.HTM
TEAC DV-R301 laser - Page 1
Forum section: electronics / repair

author: tazelikechickn
author_rank: Regular Contributor
timestamp: July 06, 2014, 01:45:55 pm
content: Hey Guys,I have been given a TEAC DV-R301 DVD player (I think it's also a hard drive, but can't find any information anywhere).It will play CDs, but not DVDs. Everywhere I have searched has said that they use a laser that uses 2 different frequencies.Anyway, I have cleaned the laser lens and it will still not play DVDs. I suspect the laser for the DVD may be faulty, but would like to try and test it or adjust it if possible before I try and buy one.Does anyone know if this is possible?
Circuit diagram for Gateway VX1100 monitor - Page 1
Forum section: electronics / repair

author: Jules
author_rank: Newbie
timestamp: July 03, 2014, 09:04:13 pm
content: Hello all,this is my first post.I'm trying to get hold of a full service manual/circuit diagram for a Gateway VX1100 crt monitor,i have searched the web exhaustively to no avail.I have heard some webchat that it is the same as the Mitsubishi 91txm.I have opened her up,and the main motherboard is very much a product of mitsubishi efforts,but can anyone confirm if the 91txm is the same as the Gateway?However i have searched the web for both the 91txm manuals and the gateway vx1100 to no avail.Can anyone help me on this?There was a website i think called esrservice which had some mitsubishi manuals but not 91txm.The fault is a loud bang and the monitor went dead.I am going to attack the PSU first,and then from there check line out transistor,i'll see if the heavy boys on the video out boards are ok.Anyone with experience on this particular model with any suggestions that can lighten my load,will be much appreciated.Secondly a quick comment,i learnt my trade about 30 yrs ago,and left it about 13 yrs ago,but i have kept a lot of knowledge alive,and i do some stuff at home when possible.I have recently come across Dave Jones from Aus,Mike, Gerry Sweeny from England,Shariar from the States,these guys are serious puppies,technically very switched on.The workshops these guys have is to die for,here i am with a 20meg Crotech and a multimeter.They've put a smile back on my face after years of being in the wilderness!!Anyway i drift, thanks for any help out there.

author: robimarko
author_rank: Regular Contributor
timestamp: July 03, 2014, 09:16:55 pm
content: No manuals avaiable online for that monitor,and yes it is Hitachi productYou will have to do this without any documentation
New Dave Repair Project - Page 1
Forum section: electronics / repair

author: apper
author_rank: Contributor
timestamp: June 26, 2014, 09:00:53 am
content: Hi All,as a EEV junkie i need a new Dave minimal 4x Session Repair Video!To pay for my fix i was wondering if we could crowd fund a AUS local Scope/Analyzer etc etc buy (Ebay AUS etc) to get Dave started?Anymore EEV Junkies around?Cheers,Apper.

author: apper
author_rank: Contributor
timestamp: June 26, 2014, 09:16:29 am
content: Hi All,just few listings from ebay.com.au, Dave should tell us what he would be interested in (if at all...):99 AUS$http://www.ebay.com.au/itm/Hewlett-Packard-HP-8922H-GSM-MS-Test-Set-with-opt-006-Faulty-Parts-Only-/221474167053?pt=AU_B_I_Electrical_Test_Equipment&hash=item3390e3990d80 AUS$http://www.ebay.com.au/itm/HEWLETT-PACKARD-PROTOCOL-ANALYZER-4952A-HP-INTERFACE-18160A-cables-/201113244011?pt=AU_B_I_Electrical_Test_Equipment&hash=item2ed348916b60 AUS$http://www.ebay.com.au/itm/Tektronix-1711J-Waveform-Monitor-Tektronix-1721-Vector-Scope-/321326098684?pt=AU_B_I_Electrical_Test_Equipment&hash=item4ad08728fc

author: EEVblog
author_rank: Unknown
timestamp: June 26, 2014, 09:18:23 am
content: Quote from: apper on June 26, 2014, 09:16:29 amI could have picked up a pallet of these for half that cost!

author: apper
author_rank: Contributor
timestamp: June 26, 2014, 09:19:54 am
content: Dave your Game then!!!

author: apper
author_rank: Contributor
timestamp: June 26, 2014, 09:21:40 am
content: Something like this?http://www.ebay.com.au/itm/HITACHI-V-068-PAL-VECTORSCOPE-/171344258268?pt=AU_B_I_Electrical_Test_Equipment&hash=item27e4e9e4dc

author: apper
author_rank: Contributor
timestamp: June 26, 2014, 10:52:36 am
content: A lot of viewers but no takers??

author: andtfoot
author_rank: Unknown
timestamp: June 26, 2014, 10:55:49 am
content: I'm tempted to get that protocol analyser myself...

author: apper
author_rank: Contributor
timestamp: June 26, 2014, 11:49:58 am
content: Just upload the Vid when you're done!!

author: andtfoot
author_rank: Unknown
timestamp: June 30, 2014, 11:36:52 am
content: Quote from: apper on June 26, 2014, 11:49:58 amWell I bought it, but I'm not promising any video.I guess I'll start with some looking and sniffing, check for usual bulging caps and scorch marks, then power it up with a series light-bulb or something...

author: SpidersWeb
author_rank: Unknown
timestamp: July 03, 2014, 12:46:08 am
content: Quote from: EEVblog on June 26, 2014, 09:18:23 amI got mine for $1, but it works and all the smoke is still inside.

author: psykok
author_rank: Frequent Contributor
timestamp: July 03, 2014, 10:58:53 am
content: Quote from: apper on June 26, 2014, 09:00:53 amHi,Yes a great repair video like the one with the LeCroy scope will be amazingAlex
HP 5335A frequency counter repair - Page 1
Forum section: electronics / repair

author: rob2630
author_rank: Newbie
timestamp: June 30, 2014, 12:53:59 pm
content: I have just got an old HP533A counter and it works fine, or at least the bits I want work fine. However, the noise from the fan puts my vacuum cleaner to shame. I have plenty of fans that will do the job but there is another problem, I can't get the lid off the counter. I managed to remove one side, the air intake side and that required a lot of persuasion presumably because it is old. Can someone tell what screws I need to remove and how it comes apart before I take a can opener to it?

author: Dr. Frank
author_rank: Super Contributor
timestamp: June 30, 2014, 01:12:09 pm
content: Should be described in the manual.It's one screw on the back side, centered on the edge (bent around) of the top plate.Undo the screw (won't come out completeley), and pull (shift) the top plate backwards.Easy.Fan always has to be replaced. Check your 5335A vintage / version, either 110V or 24V type, again see also manual.Either buy original Papst one, or replacement. See foregoing threads about the 5335A, with photos.Frank

author: rob2630
author_rank: Newbie
timestamp: June 30, 2014, 02:03:29 pm
content: Thanks Frank, now you have said that I know where that screw is, under the "Do not remove" sticker! I should have known to look there first. I have seen the other posts on this subject which is why I joined this site. As far as I can make out the counter is 1984 but in clean condition. As I say, thanks for your help.By the way, the manuals I have been able to find so far do not mention taking the thing apart they just say remove the top cover. The fan as far as I can see through the back is marked 30v. I will measure tonight and dream up a suitable replacement.
Panasonic surround amp problem  - Page 1
Forum section: electronics / repair

author: BLUEX Electronics
author_rank: Newbie
timestamp: July 03, 2014, 11:54:54 pm
content: I just got a Panasonic surround amplifier from our local transfer station. I plugged it in and it came on with a really dim display and for a while I thought that it was really broken. Anyway I finally noticed that it was on, then the relay clicked and it read "OVERLOAD" on the display. I turned the speakers off and turned it back on and it said "OVERLOAD" again. I opened it, nothing looks wrong, no blown fuses, no bulging capacitors ETC. What can be wrong here?Thanks-Josh

author: Fank1
author_rank: Regular Contributor
timestamp: July 04, 2014, 01:25:56 am
content: Acts like an output transistor is shorted.
New sub forum for repairs? - Page 1
Forum section: electronics / repair

author: What_NZ
author_rank: Regular Contributor
timestamp: June 28, 2014, 05:31:41 am
content: Hi,Just wondering if it was possible to have an area in the Forum for repairs.An area where people can ask for help to repair something or show something they have repaired and what was faulty.Maybe the new Repair section could be divided into Test Equipment and Other products.Just a thought.oh posted here as I didn't know where to ask this question...

author: tautech
author_rank: Super Contributor
timestamp: June 28, 2014, 05:51:40 am
content: Similar was discussed a few months back in another thread:https://www.eevblog.com/forum/chat/divide-'test-equipment'-into-sub-sections-yay-or-nay/Might be worth a read and/or revive it.

author: What_NZ
author_rank: Regular Contributor
timestamp: June 28, 2014, 05:59:47 am
content: Thanks and good point.My fault for just reading the Post subject.Everyone please don't post here, instead post in the thread mentioned above.Post here as the other thread is more about Test equipment.

author: Rasz
author_rank: Super Contributor
timestamp: June 28, 2014, 07:40:03 am
content: Repair/Service area would not fit Test Equipment section, if anything it would need its own place.Illogical to post solutions for washing machine programmer/flat screen/laptop under test equipment.

author: Tinkerer
author_rank: Frequent Contributor
timestamp: June 28, 2014, 05:15:24 pm
content: A section for this would make alot of sense. Currently, much of the repair stuff ends up in Project/Designs, or Beginners

author: AlfBaz
author_rank: Super Contributor
timestamp: June 29, 2014, 02:15:10 am
content: +1With a couple of stickies such as general fault finding/troubleshooting guide, common gotcha's, repair techniques (reflowing, PCB tracks, vias, dead bug and other bodges) and maybe common faults thread

author: kolbep
author_rank: Frequent Contributor
timestamp: June 29, 2014, 10:14:56 am
content: I Agree.Seperate Repair section would be better.p

author: rdl
author_rank: Super Contributor
timestamp: June 29, 2014, 02:26:21 pm
content: Apparently somebody thought this was a good idea. There is now a "Repair" section all to it's self.

author: Stonent
author_rank: Super Contributor
timestamp: June 29, 2014, 04:15:28 pm
content: The top sticky should be titled "Thou shalt check voltages!"
Current Draw of an old Sony Handycam? - Page 1
Forum section: electronics / repair

author: polishdude20
author_rank: Contributor
timestamp: July 04, 2014, 04:39:34 am
content: Hello!I've got an old Sony TR200 Handycam and lots of Hi8 tapes of family memories! I've lost the charger long ago and the batteries are dead. I know I can buy a charger+ batteries on ebay for around $30 but I want to build my own power supply that can provide the 7.2 volts the camera needs.The problem is that I don't know the current requirements a camera like that would need. I've made a simple LM317 circuit to provide 7.2 volts but the max current the LM317 can provide is 1.5amps. When I turned it on, the little LCD screen kept turning on and off and it was clicking probably due to the inside motors being engaged and failing because they couldn't get enough current!So does anyone know how much current this puppy needs to operate?

author: Richard Crowley
author_rank: Super Contributor
timestamp: July 04, 2014, 05:13:59 am
content: If it isn't specified on the nameplate or in the user manual, you could power it from a bench supply and actually measure it. For that matter you could simply power it from the bench supply until you get all the tapes captured/copied. If nothing else, I would assume I need 5A. If it still doesn't work, then it is broke.It is possible that 1.5A is insufficient because some mechanical part/bearing is frozen and it is drawing more than its normal design current.There are plenty of simple circuits that will boost the current capacity of a 3-terminal regulator with a bitter pass transistor and a few resistors.It isn't particularly clear to me why it would be worth building a dedicated power supply for it?

author: What_NZ
author_rank: Regular Contributor
timestamp: July 07, 2014, 09:13:48 am
content: Where are you trying to input the power?If it is where the battery connects to, then you will need 7.2V and more than 1.5A.If you are connecting to the DC input jack it is 6.5V @ ~1.8AMost camcorders cycle the mechanism during power on so initial peak current will be higher. Maybe a large capacitor will help with the peak current.
Tektronix TDS7104 repair issue, motherboard - Page 1
Forum section: electronics / repair

author: acbern
author_rank: Frequent Contributor
timestamp: April 20, 2014, 08:18:54 am
content: months ago i bought a non-working tek td7104. it was reported to not pwoer on with the front switch, but power on with the internal jumper. it was sitting there for a while because I had no time left to work on it, but have now, so here I am.first find is, true, with the jumper shorted (it is decribed in the service manual, which does unfortunatelly not go in much detail about anything), it powers up, but thats all. screen blank. I deactivate the ppc board and video (by two jumpers) and i measure all voltages, they are ok, also 5vstdby (so my initial assumption that the psu has an issue seems wrong).so its now only the nlx baord that should be active, all others being deactivated. so i measure, and issue is, the pci bus reset coming from the nlx board is active, so the board is in reset. this board is an intel su810 nlx mainboard, essentially (as i understand, not being a motherboard guru at all) an at-motherboard design in another form factor, based on the 810 chipset. I measure other input signals (pw_ok, soft_on/off), they are correct.since i could not find any schematic of this board to trace the reset issue, i am stuck. replacing the nlx board would be the next thing, but that will cost me 100 euro, and may not be the right thing at all, just a guess.so if anybody has some hints, would be nice. thinking arround measurements on board the nlx or on the pci connector to determine the root cause of the reset, to determine if a new nlx board is the right thing.so that means any background re. how the restet is generated (when does a reset occure, what signals need to be present on the pci bus), what chip is generating it? and so on.any other hints wellcome as well of course.

author: mongo747
author_rank: Newbie
timestamp: June 26, 2014, 06:20:01 pm
content: I have a TLA 622 with same motherboard and similar problem. I have found what I think is that motherboard for about $20 us.I got it at an auction and it turned on and was able to get past the log in. It sat for a month or so and now it does power on.Trying to figure out how to isolate it. I would like to get in touch and see if we can work through our issue together. Please send me a message if you would like to give it a shot. Thanks
Satlook Mark III repair - Page 1
Forum section: electronics / repair

author: fubar.gr
author_rank: Unknown
timestamp: May 30, 2014, 04:41:23 pm
content: They brought me a broken Satlook Mark III, which is basically a portable CRT TV with a satellite receiver and is intended for antenna installation technicians.The first thing I realized was that the built-in battery ( it has a 12 volt UPS-style battery) was dead at just 1.5 Volts.I took the dead battery out of the device and connected the cables to my bench power supply. As soon as I turned it on, it started to make a loud high pitched, alternating sound, so I turned it off immediately.I then took it apart. There were two boards, the first having some voltage regulators and the other having the flyback and generally the crt control circuitry.I looked for visibly blown capacitors or anything blown but did not see anything .The CRT board had two TO-220 transistors on large heatsinks . I tested them off-circuit and they looked fine.I removed the flyback from the board but I do not know how to test it. It has E176185 MC-FB-001 on it but couldn't find a datasheet.Then, at the other board I saw something strange . It has several voltage regulators and I found their datasheets. But this one, while marked as VR2 on the board, the component (BUK555-100A) is actually an n-type MOSFET.I thought that was simply a mistake. But I noticed that the third pin (source) is connected directly to the battery positive. This can't be right, can it?Also, when this board is powered on it's own, it draws around 200mA. Isn't that too much?So far I have the following questions :1 ) How do I check the flyback? I do have a UNI-T 513 insulation resistance tester if that helps.2) Is the MOSFET placed correctly there?

author: Fraser
author_rank: Super Contributor
timestamp: May 30, 2014, 07:55:55 pm
content: 2 comments from me....... LOPT failure unlikely on these units and best diagnosed in circuit. Failure usually kills the driver transistor and you lose power rails. And secondly.....I attach the schematics of the Satlook III for your useEnjoy ..... they are pretty simple unitsOh and VR2 appears on the second schematic (Tuner) in the bottom right hand corner. It's part of the battery charger circuit

author: Fraser
author_rank: Super Contributor
timestamp: May 30, 2014, 08:21:19 pm
content: Just noticed on your picture of the LOPT......are those PCB feed-throughs still attached to the pins ? If so you will need to ensure that the pins are correctly soldered to the PCB on both sides otherwise you will have more problems to solve.

author: fluxcapacitor
author_rank: Frequent Contributor
timestamp: May 31, 2014, 12:05:05 am
content: Is there something missing above R126 .Can you check R67 ,R126 and R117 .
HP 8753C VNA repair case - Page 1
Forum section: electronics / repair

author: Bud
author_rank: Super Contributor
timestamp: May 27, 2014, 03:50:57 am
content: Here is a fascinating story about a tiny capacitor that took down a monster $$$K device. I did this repair some time ago on my 8753C VNA.VNA all of a sudden stopped working. Could not power it up anymore. It looked as if the protection circuit kept triggering on one of the secondary voltage supply rails. After troubleshooting the problem was traced to the power supply which stopped producing the proper +5.1V voltage.Inside the power supply. The left half is the power stage and rectifiers. The right half is line input and the controller circuit, which was of my interest.I had to reverse engineer the PS unit a bit around the controller IC - see a fragment of the schematic below . To my surprise, found a 0.22uF bypass capacitor developed a leak, corrupting the reference voltage on pin 2 (the controller IC error amplifier). That caused the power supply +5V channel voltage change erratically between 4.5 to 5.1V which apparently triggered the under voltage protection circuit on the 5.1V supply rail which in turn was shutting down the whole power supply.And here it was the bad guy... darn penny cap that was causing multi $$$K pain in the arseThe bad capacitor was replaced with a mica 0.22uF new one. After the replacement the +5.1V voltage became stable within 0.1mV and the problem was gone. The VNA powers up normally now.

author: TVman
author_rank: Frequent Contributor
timestamp: May 27, 2014, 04:22:42 am
content: Well, what do you expect these days?Do you expect it to last 100 + years with no problem?(Conspiracy theory time)Those designers purposely do that so that way they can charge you A grand just to fix that tiny, stupid capacitor.It's just to get money.And, Hey good job finding that fault.Hunor

author: AlfBaz
author_rank: Super Contributor
timestamp: May 27, 2014, 04:45:43 am
content: Nice work tracking down that fault Bud.SMPS's always give me ulcers, if you get it wrong sparks can fly.The last one I fixed was for a wavetek signal gen. Frustratingly it looked a hell of a lot like a PC power supply but the voltages were all wrong. I found a bad cap, replaced it and still nothing until a member here pointed out that some of these psu's wont produce output without a load. I promptly loaded it up and bingo, worked like a charm
SOLD (UK): Pure Avanti Flow internet radio ipod dock thingy (needs repair) - Page 1
Forum section: electronics / repair

author: TopLoser
author_rank: Unknown
timestamp: June 10, 2014, 02:44:27 pm
content: Something else that's taking up space on my desk. It worked fine until last week. Switched it on one morning and no sound anymore. Everything else seems to work, connects wirelessly to my network, displays FM and DAB station names, recognises ipod, remote works. Just no sound. And yes I did poke the mute button a few times just to make sure....http://www.whathifi.com/review/pure-digital-avanti-flow£20 plus shipping anybody?SOLD, thank you
VHO Fluorescent Ballast: IceCap 660 Teardown / Repair - Page 1
Forum section: electronics / repair

author: theatrus
author_rank: Frequent Contributor
timestamp: May 17, 2014, 01:03:28 am
content: My venerable IceCap 660 VHO ballast (which I use with T5 lamps) on my aquarium started flickering and would not restart. After smelling the sickly smell of pop electrolytics, I decided to test the "Repairable" moniker.First step not pictured: drilling out 4 rivetsYup, thats popped. And sprayed everywhere.The logic section. The connector on the bottom is for a dimming control signal.IR2110 - driver IChttp://www.irf.com/product-info/datasheets/data/ir2110.pdfTL594 PWM controller:http://www.ti.com/lit/ds/symlink/tl594.pdfLM339 Comparator:http://www.ti.com/lit/ds/symlink/lm339.pdf555 Timer(time the ignition cycle?)LM393 precision comparatorhttp://www.ti.com.cn/cn/lit/ds/symlink/lm393-n.pdfThe ballast transformers.The input section (with the caps removed)A current sense transformer (likely?) hiding under the big transformers. There is a row of passives under each of the two transformers.IGBT:http://www.irf.com/product-info/datasheets/data/irg4pc40ud.pdfI don't have caps which will fit in the height footprint of the case, but those are on order.

author: Evil Lurker
author_rank: Regular Contributor
timestamp: May 19, 2014, 03:09:04 am
content: Wow that looks to be like a fairly high quality build. There are tantalum capacitors on the control side and even a silver mica capacitor in there!If it were me I would consider doing a total recap job + replacing the MOV's. Might as well get all of them while you are in there.

author: theatrus
author_rank: Frequent Contributor
timestamp: May 19, 2014, 04:12:28 am
content: I figured it was of some interest as these types of ballasts are usually potted affairs - this is one of the few I've run into which was not.Good catch on the silver mica - didn't even see it.

author: amyk
author_rank: Super Contributor
timestamp: May 19, 2014, 12:04:14 pm
content: That case style on D3/D4 is pretty rare too. I remember seeing those in military hardware.

author: theatrus
author_rank: Frequent Contributor
timestamp: May 19, 2014, 02:41:48 pm
content: MR756 Silicon 6A diodes:http://www.onsemi.com/PowerSolutions/product.do?id=MR756ON has discontinued them, but they do appear to be available from other sources.

author: thm_w
author_rank: Super Contributor
timestamp: May 21, 2014, 01:06:32 am
content: Nice macro shots.
Mobile phone repair and servicing, what do you actually do? - Page 1
Forum section: electronics / repair

author: Electric flower
author_rank: Regular Contributor
timestamp: May 20, 2014, 07:15:33 pm
content: Anyone out here who is in this field?What things do you do mostly?What tools do you use mostly? (besides hot air gun, solderin iron)Do you use osciloscope?What are the most usual problems?Could you give more info about things you see every other day and details?Any advice for a begginer?I have oportunity to work during summer at one shop that specializes mostly for mobile phones, man has offered me a job becouse of past experiences but i explained him i never messed with phones before...?Thanks for your time and sorry for bad English.

author: tszaboo
author_rank: Super Contributor
timestamp: May 20, 2014, 07:49:47 pm
content: Well, mobile phone repair manuals look like this usually:1: Pry it apart with a spudger2: Toss the motherboard in a special bin designated for industrial waste3: Put there a new motherboard(suspected) 4: If the customer is lucky turn it on , but still dont check if the original problem is solved5: Back to the customerWhy didnt you asked the guy what is involved with the job? You have every right to know what your job will be!

author: Electric flower
author_rank: Regular Contributor
timestamp: May 20, 2014, 08:13:31 pm
content: Quote from: NANDBlog on May 20, 2014, 07:49:47 pmFast blow fuses blew due to inductive kickback of a job offer... my mind goes blank often.He mentioned that most of his job sums up to comunication and smiling with a customer.

author: nctnico
author_rank: Super Contributor
timestamp: May 20, 2014, 08:22:37 pm
content: In Asia many shops do component level repair like soldering loose connectors and replacing LCDs and cameras. Besides that there is also a lot of work in re-installing the phone's operating system. Preferably without losing the customer's data.

author: Legit-Design
author_rank: Frequent Contributor
timestamp: May 20, 2014, 09:11:57 pm
content: Here it goes something like this:Phone has problems with volume button which is not working because it's most common failure mode. Yes there is something physically wrong with the volume button.1: Check if customer has installed custom rom, yes custom rom might leave traces even if original was reinstalled2: Send it back to customer informing they have voided the warranty because of custom rom3: Offer to fix the unrelated problem for a cost more than a new phoneAlso real repair people don't bother trying to remove working LCD from broken digitizer, since digitizer is cracked the whole module can be replaced. Digitizer is typically glued to LCD panel and can be easily repaired with new digitzer from ebay by any hobbyist. However there are some exceptions like some newer iphones.

author: Stonent
author_rank: Super Contributor
timestamp: May 20, 2014, 09:58:24 pm
content: I got a job offer for that when I wasn't looking for a job, they wanted to pay like $8.50 an hour.
Repairing an 80's Dick Smith VZ300 by reverse engineering the custom logic - Page 1
Forum section: electronics / repair

author: Clocky
author_rank: Newbie
timestamp: May 06, 2014, 02:58:26 pm
content: This was my last little project. I've also just completed the video memory upgrade from 2kb to 8kb so now the computer can display the highest possible resolution 256x192 1 bit clr that the MC6847 VDG is capable of. I'm just getting back into electronics, so please excuse the noobishness.I'll post a video of that soon and provide more detail of the whole project including technical details. The video below is scant on detail apart from the general links when you click more though.Thanks for looking.
eyeball repairs for ee work, looking forward to scaring people at makerspace - Page 1
Forum section: electronics / repair

author: jh15
author_rank: Frequent Contributor
timestamp: May 08, 2014, 06:18:37 am
content: I just had cataract surgery, to improve my vision. Decades ago I read in PF Reporter or Electronic Servicing Magazine about the horrors of needing trifocals glasses.If there is a thread of this, poke me there.I learned that one should research a lot before going for surgery, good and bad. I read this forum as my favorite past-time, wish I had asked here first.For fun stuff, I wanted to document color changes between eyes like color perception, and use GIMP to make my new eye vs old eye color rendition the same on the monitor., it was huge, now brain is making them the same.Some facts: I have a borg type moving cat's reflection out of my eye to friends which freak out most users, but i will find it fun.Anyway it is late, will pursue tomorrow.

author: Stonent
author_rank: Super Contributor
timestamp: May 08, 2014, 06:27:57 am
content: I used to work for a company that made IOLs for cataract surgery and lasers for Lasik. I've seen some gross eyeball videos...

author: JulietMikeBravo
author_rank: Contributor
timestamp: May 08, 2014, 01:06:45 pm
content: Quote from: jh15 on May 08, 2014, 06:18:37 amNice, probably due to the difference in refraction index of the lens and surrounding translucent eye stuff?I have keratoconus, a slow progressing cornea disease. One eye has been treated with a corneal transplant, the other eye still has to be treated. No contact lens tolerance in that eye so I currently have only one useable eye. Unfortunately glasses cannot correct KC. It is a bit annoying to have no proper depth perception when soldering but overall I manage OK.BTW, cataract surgery is quite common, especially with the elderly. A lot of surgery is done on outpatient basis with local aneasthesia. If I could I would happily exchange my messed up corneas with an easily replaceable clouded lens. Did you have complications?
tektronix 2710 spectrum analyzer repair - Page 1
Forum section: electronics / repair

author: livin
author_rank: Newbie
timestamp: April 23, 2014, 07:22:59 pm
content: Hi,I am working on Tektronix 2710. When i try to do set up factory default power up settings(utility menu - stored settings/desplays - factory default power-up) the following message appears." cannot overwrite saved display''.Can someone tell me what does this means? And a solution to stop getting this message.Thank you.

author: casinada
author_rank: Frequent Contributor
timestamp: April 23, 2014, 09:38:02 pm
content: http://www.ko4bb.com/manuals/index.php?dir=Tektronix/Tektronix_-_2710_Spectrum_Analyzer

author: livin
author_rank: Newbie
timestamp: April 23, 2014, 10:17:25 pm
content: Thanks for the link. @casinadaseems like A,B,C,D registered were already containing stored data's. So when i tried to do a factory power on settings i was getting "cannot overwite saved display" message.Solution: press save in display storage and then press each registers until all red and green lights across each registers are turned off.then again try to do the factory default power up settings(utility menu - stored settings/displays - factory default power-up). Thisthis time i dint get the error message.

author: Pinkus
author_rank: Frequent Contributor
timestamp: April 25, 2014, 07:30:19 am
content: The Tektronix 2711/2712 (and thus the 2710, which is the same, just comes with a different front keyboard) is a nice device. I owned one for many years and sold it a year ago to purchase a Rigol DSA815 as this had a tracking generator which is rare and expensive for the Tektronix.One hint if you need to repair this device: Get the schematic / service manual of the 2712 from the Tektronix pages. There are in much better quality and the schematic (but the keyboard section of course) is 99,9% the same.

author: livin
author_rank: Newbie
timestamp: April 25, 2014, 02:12:29 pm
content: Alright. Thank you for the reference. @pinkus
For sale - contents of tv repair shop - Page 1
Forum section: electronics / repair

author: tecman
author_rank: Frequent Contributor
timestamp: April 18, 2014, 03:37:27 pm
content: I am helping a friend who is selling the contents of his father,s shop, who recently passed away. The items will be pickup only, in the Allentown PA area.Included are drawers and drawers of parts, some test equipment (Leader Scope, meters, HV probe-meter, isolation xformer, metered variac, etc), boxes of tubes, and a lot more.He wants $500 for the whole lot.if there is any interest, pm me with an email address and I can send more pictures.paul

author: N2IXK
author_rank: Frequent Contributor
timestamp: April 18, 2014, 03:54:36 pm
content: You might want to post this over at videokarma.org, as well.

author: firehopper
author_rank: Frequent Contributor
timestamp: April 19, 2014, 12:09:23 am
content: wish I had the room and $500. but I'm not sure that I'd be able to use it anyway.. I'm not far from allentown, pa myself.

author: TheBorg
author_rank: Frequent Contributor
timestamp: April 19, 2014, 03:34:46 am
content: Any decent LCR meters that might be shippable?GLWS though. Wish I lived closer...

author: deth502
author_rank: Frequent Contributor
timestamp: April 19, 2014, 12:09:34 pm
content: i live just over an hour from allentown, but i knew an old guy here who did tv repair in his basement that died a few years ago, and damn, seeing that pic brought me back. that looks EXACTLY like his shop, except ive never seen a flat screen or rear projection there.
Tektronix TM500 repair/calibration cable - Page 1
Forum section: electronics / repair

author: eurofox
author_rank: Unknown
timestamp: April 19, 2014, 11:33:42 am
content: For the happy owners a Tektronix TM500 modules, a link to buy a cheap extension cable to allow test/repair/calibration.Those modules are now quite cheap and some are interestingI just got a working 250Mhz pulse generator to complete my collection.http://www.jammaboards.com/store/tektronix-tm500-series-extender-kit-tm500-kit.htmleurofox