hybridfree/eevblog-posts huggingface dataset:
Help me repair Tek 2440 - Display Flicker when running CTE Calibration - Page 1
Forum section: electronics / repair

author: chihaxinh
author_rank: Regular Contributor
timestamp: April 27, 2016, 03:30:52 am
content: Hi EverybodyI have on Tek 2440 have problem , when running in 5 10 min have gain error and runing selftest fail . I open case and force cooling CCD and DAC module by other fan, everything ok when running 1 hour or more, selftest Pass.Inside case not have must dusty so heatsink very clear. I checking power rail it's all OK , voltage value and voltage rip OK.So i runing coldstart to carlibration Tektronix 2440 . Runing ATTEN and TRIGER pass but CTE not pass.NVRam in 2440 using static cmos HM622556LP-12 , and external Lithium battery ( Checking 3.7V OK - Battery not dry )So I attach picture and video clip , when runing CTE calibration , display flicker and allway report overload in 50R input ATTEN . I Don't know why CTE Calib auto switch to 50R ATTEN inputAll information reference you can see in topichttps://www.eevblog.com/forum/metrology/tek2440-mini-teardown-nvram-replacement-and-calibration/I concern register memory in NVRam wave form capture have error.Many thank so much!Edit : Display Flicker only when runing CTE Calibration mode ( You can see in video clip )

author: LazyJack
author_rank: Frequent Contributor
timestamp: May 09, 2016, 07:36:36 am
content: Ah, the overload explains a lot.CTE calibration switches the 50 termination on, as the official calibration procedure uses a pulse generator with 50ohms output. If the 50ohms overload comes on, then your input voltage is too high. You should lower the amplitude or insert a attennuator. The calibration requires a fairly low signal level 120mV or something like that. It needs to be 6div in amplitude in whatever the scope sets up the volts/div.Other than centering the signals, you should not change any other setting that the scope sets up for the cal. The flickering is probably because of the overdrive.
APC SMT1000I display problem - Page 1
Forum section: electronics / repair

author: gameru
author_rank: Contributor
timestamp: May 09, 2016, 12:11:17 am
content: GreetingsToday i was scammed!I bought an APC SMT1000I,the seller told me the unit it is in perfect condition.When i received the unit i discovered the display don't work.I think the display is the only problem.I powered two light bulbs of 100W each.I measure the Voltage and is 228V constant,but on the display does not appear anything.I tried to take apart the display from front mask,but it has too much clips.Can someone tell me if can be repaired or where can i find parts ?
LCD mirror display - Page 1
Forum section: electronics / repair

author: CalG
author_rank: Contributor
timestamp: May 06, 2016, 11:55:10 pm
content: Sorry, I posted this same question in the "projects" forum. 'not paying attention I suppose.Any wayI have an older VFD with an LCD operator MIO interface for monitor and programming.The LCD screen is less than brilliant in regards to it's ability to display information screens. Today, when the device was powered up, the LCD screen displayed the page as a mirror image.Am i correct not to consider the LCD module it's self as the bad component

author: BMack
author_rank: Regular Contributor
timestamp: May 08, 2016, 01:13:23 am
content: I've never heard of that before but I did fix(sort of) a TV and end up with an upside-down picture. It was a warranty unit so instead of sending me another main board they bought out the set.I would not say the panel is the problem, I'm thinking the issue is in the main board.
what IC is that ? Dwa108-A - Page 1
Forum section: electronics / repair

author: boo9
author_rank: Contributor
timestamp: May 06, 2016, 10:20:54 pm
content: Could somone please help me identify following element from ATX power supply, Delta DPS-280FBMay be the IC has different more popular designation ?I cannot locate datasheets or schematicsHint: There is a LM339n (quad comparator) next to this chip on the PCB.

author: amyk
author_rank: Super Contributor
timestamp: May 07, 2016, 02:35:32 pm
content: Delta used proprietary controllers in their PSUs. Trace out the circuit and see if that gives you any clues if it's similar to some other common one.

author: gamalot
author_rank: Super Contributor
timestamp: May 07, 2016, 03:41:41 pm
content: I am not 100% sure, it may be compatible with TPS5510, hope this helphttp://www.ti.com/lit/ds/symlink/tps5510.pdf

author: boo9
author_rank: Contributor
timestamp: May 07, 2016, 09:42:36 pm
content: thank you very much, guysEDIT: the measured voltages on the pins of the IC match the TPS5510 specs.many thanks.
Firmware/eprom-dump  of 34401a - Page 1
Forum section: electronics / repair

author: meandeev
author_rank: Regular Contributor
timestamp: May 06, 2016, 09:04:15 pm
content: Hello,does anybody have a firmware image /eprom dump of a 34401a? Any version would be ok, better is one from an eprom labelled "34401 88823 4.0"

author: JFJ
author_rank: Regular Contributor
timestamp: May 06, 2016, 10:06:21 pm
content: Quote from: meandeev on May 06, 2016, 09:04:15 pmThere's a version 2.22 (together with a front panel EPROM) on the KO4BB web site:http://www.ko4bb.com/getsimple/index.php?id=manuals&dir=HP_Agilent/HP_34401A_6.5_Digit_Multimeter

author: meandeev
author_rank: Regular Contributor
timestamp: May 07, 2016, 08:40:02 pm
content: Thank you very much for the link!
E3631A repair - Page 1
Forum section: electronics / repair

author: Big Dog
author_rank: Contributor
timestamp: May 07, 2016, 01:24:50 am
content: Hi folks,Looking for a 8051 for the front panel of the E3631A.Either the original part or the hex file for it and I could flash one myself, if the 8051 is around in flash.Or am I screwed here and have to buy a new front panel?Jim

author: Big Dog
author_rank: Contributor
timestamp: May 07, 2016, 04:45:25 am
content: found the other thread on the 34401-88804. so I just bought a display board for the 33401a and will pull the chip from it.
(solved) fluke 8502a Ohm 's card - Page 1
Forum section: electronics / repair

author: whitevamp
author_rank: Regular Contributor
timestamp: May 06, 2016, 03:21:48 pm
content: my ohm 's card is way out so i decided to see if i could figure out why it was out, and in testing some components i found a resistor that was way low, its reading 7.75k and it should be 4.091M 2w ( R41 )so the question is this resistor is bad right? i think it is.and if it is bad dose any one know where i can get it, or if i can sub it for a different one, i have looked at digikey and mouser, and a few other places but i cant find this part.

author: Vgkid
author_rank: Super Contributor
timestamp: May 06, 2016, 03:41:37 pm
content: Can you take a picture of the resistor? Did you measure it out of circuit?

author: Vgkid
author_rank: Super Contributor
timestamp: May 06, 2016, 06:49:44 pm
content: For that resistor use a 4MEG metal film in series with a 90.9K mf resistor for testing. For something more accurate(and expensive) use 2 caddock (USF370-2.00M-0.01%-5ppm) 2 megohm resistors in series with the 90.9K resistor. I don't believe that caddock would do a one off resistor, that would be even easier. Option 1 will cost you a few bucks, option 2 will be about 70.

author: whitevamp
author_rank: Regular Contributor
timestamp: May 06, 2016, 07:53:58 pm
content: Quote from: Vgkid on May 06, 2016, 03:41:37 pmyeah was out of the board.Quote from: Vgkid on May 06, 2016, 06:49:44 pmok thank you.

author: Vgkid
author_rank: Super Contributor
timestamp: May 06, 2016, 08:57:32 pm
content: This is a better option for precision resistors. Caddock usf-340. 22.xx at digi-key. Lower cost, and smaller size.
Nicolet integra 60 - Page 1
Forum section: electronics / repair

author: wokkel
author_rank: Newbie
timestamp: February 17, 2016, 09:41:35 pm
content: Hello all,I bought a Nicolet integra 60 with some problems.The first problem was that the oscilloscope would't start up.I fixed it with a new memory battery, and replaced the circuit that switched from back up battery to powersupply (it was damaged by the old leaking battery)The next problem is that only 1 of the four channels displays the correct amplitude. The other 3 channels show a signal but the amplitude is far too weak.My question:Does anybody have a manual, or even better a service manual?Thanks !

author: wokkel
author_rank: Newbie
timestamp: May 06, 2016, 08:09:33 pm
content: It's been a while and i made little progress unfortunately.I found the manual, but still no service manualif anyone could help me find the datasheet of the following chip:The text on the chip is SSSB157 9652Thanks !
Repair advice for Samsung Galaxy Tab 2 10.1 - GT-P5110 - Page 1
Forum section: electronics / repair

author: Kikerumbo
author_rank: Newbie
timestamp: May 06, 2016, 07:36:03 pm
content: Hi everyone and thanks in advance.First of all, I'm sorry because my english is not good and I hope you can understand what I'm trying to say.Second, I'm not an electronics expert, I just have the idea that if it's already not working, I don't have anything to lose trying. And I love to do the things myself. That said...I have a friend's tablet, a Samsung Galaxy Tab 2 10.1 that doesn't want to turn on. I tried for hours the procedings I found via Google without any luck. After all that I opened it unpluged the battery and check the voltage. It was 4.12v so the battery shouldn't be the problem (from my little understanding).I followed the service guide from Samsung (I can't attach it since it's too heavy 5,13Mb). Since I don't know how to test if the ON-VOLUME buttons-ribbon works (can you tell me how?), I found at this very forum another post (https://www.eevblog.com/forum/repair/how-to-jumper-the-g-tab-2-(gt-p5110)/) where someone asked how to "jumper" the ON button, so I did that. I used a wire to connect the pins 1 and 2 together (used a little piece of tape to isolate those pins so I couldn't touch anything else with the wire), but nothing happened.After that I plugged the battery and then the charger. The zone surrounded in red started to heat up and it burnt at the touch. I unplugged the charger and the battery. After this, the battery was on 3.55v. With the battery unplugged, the motherboard of the tablet gives 0.7v.Now it's all disassembled waiting for the motherboard to spend that little energy it still has, kind of hoping it works like the BIOS of a PC motherboard, and it resets to factory settings.Well, after all this story of sorrow I came here for help. If you could give me any idea, it'll be much appreciated.Have a nice weekend!
HP Touchsmart 520 - IPISB-NK - Page 1
Forum section: electronics / repair

author: IHackStuff
author_rank: Newbie
timestamp: May 03, 2016, 04:11:11 pm
content: So I've been working on this motherboard for a while now. I have the schematic pdf of a very similar (but just different enough to be annoying) motherboard. It will work, rarely. The rest of the time, it powers up and just sits there. No POST. No error beeps when I pull the RAM. Nada.I went all over the board checking voltages and power_ok signals. VAXG wasn't coming up, so I forced it by changing a resistor value. After that, it worked a few more times, and I thought I had it solved. But, I was wrong, and now it's dead again.Any ideas or tips of where to look now would be greatly appreciated.

author: KE0ITR
author_rank: Newbie
timestamp: May 06, 2016, 01:54:46 am
content: I had a similar problem with one I worked on. I ended up swapping the processor and it worked fine afterwards. The symptoms I had were it would turn on, but the LED for the power button (white) would not come on, and the CPU fan ran at 100%. No system beeps or any other indications.After the cpu swap the system has worked fine for the last 3 months.
SOLVED..Thanks)Help to identify a transistor in this Rivera guitar amp schematic - Page 1
Forum section: electronics / repair

author: Planobilly
author_rank: Regular Contributor
timestamp: May 05, 2016, 12:08:42 am
content: Hi,http://bmamps.com/Schematics/Rivera/Clubster%2025-45.pdfThis is a Rivera Clubster 25 guitar amp.From the input there is R102 to C101 to Q101 which is marked as 1FN6448 on the schematic. There is only a Rivera part numbers on the transistor. I assume it is a transistor. Round metal top with three legs.What is Q101? Data Sheet?Thanks,BillyOne of the issues is that I have no signal on the grids of V1 and I assume this component may be the cause.

author: Andy Watson
author_rank: Super Contributor
timestamp: May 05, 2016, 12:33:52 am
content: It is a junction FET. Can you read the part number on the device? Could it be 1FN6449?Q104 appears to be a 1FN6449 - if this is the correct part number it is a Jfet made by InterFET. They claim it is equivalent of a 2N6449.http://www.interfet.com/Support/JFET-Naming-Conventions/Datasheet:http://www.interfet.com/datasheet/IFN6449/

author: Planobilly
author_rank: Regular Contributor
timestamp: May 05, 2016, 12:48:49 am
content: No part number other than (Rivera 104-010-0450) that is marked on the device.I assumed a FET of some sort. I think it is possible that it is a 6449. The schematic is a PITB to read!!!!Also...thanks for the helpCheers,Billy
HP8559A or HP1741 Knop - Page 1
Forum section: electronics / repair

author: ggolfbs
author_rank: Newbie
timestamp: February 18, 2016, 12:49:07 pm
content: Hi, i need the Knob Freq Span/div from the HP8559. i thing the knob is the samefrom the HP1722A, HP1725A, HP1740 and 1741 and 1745 time/div.who can help?best regards from Guenter

author: gearhead
author_rank: Contributor
timestamp: March 07, 2016, 05:46:16 am
content: Do you have a picture of what you need? I have 2 old HP scopes for parts. I may it.

author: spie
author_rank: Newbie
timestamp: May 04, 2016, 01:00:27 pm
content: Hi I need the same, even bought another1740 off ebay but same problem a broken plastic delay shroudif anyone knows where I can get a replacement please advisethanks
need help identifying component  - Page 1
Forum section: electronics / repair

author: DarkZero
author_rank: Regular Contributor
timestamp: May 04, 2016, 09:04:16 pm
content: need help to identify this what i think is transistor

author: DarkZero
author_rank: Regular Contributor
timestamp: May 04, 2016, 09:13:30 pm
content: i found datasheet i always forget to put package let this post be remineder to me ....https://www.google.rs/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=0ahUKEwjMzd6CrMHMAhVMkiwKHdJ4ClwQFggbMAA&url=http%3A%2F%2Fwww.infineon.com%2Fdgdl%2FInfineon-BFN24_BFN26-DS-v01_01-en%255B1%255D.pdf%3FfileId%3Ddb3a304314dca38901156a1bcc68214d&usg=AFQjCNGwmjRrWYygKluQZ9c5XBhiK-BNHA&sig2=1s_fILrEwMLZUCsBe42Djw

author: tautech
author_rank: Super Contributor
timestamp: May 04, 2016, 09:18:34 pm
content: Ha, I was going to remind you about package but I figured it was a SOT23But the suffix was the confusing bit until I looked at some results:http://www.s-manuals.com/smd/fjNot sure if any of those match.Sometimes one needs to identify where a component is used and what "building block" of a circuit it might be in, that often narrows down a search heaps.

author: DarkZero
author_rank: Regular Contributor
timestamp: May 04, 2016, 09:26:36 pm
content: i measure 210v on its collector so im sure its bfn26 because its high voltage transistorand its part of smps power supply of my downdraft cooktop the thing wont start and tny267 is good
Audio Precision System 2 self test fail - Page 1
Forum section: electronics / repair

author: tan98010
author_rank: Contributor
timestamp: May 05, 2016, 07:59:09 am
content: Recently i am trying to run through the Audio precision system 2 self test and there is a few failure can anyone help me to identify the failure module....?what is ANL Module...?05/05/16 15:31:0605/05/16 15:31:06 **********************************************05/05/16 15:31:06 ANL Module CHECKS05/05/16 15:31:06 **********************************************05/05/16 15:31:0605/05/16 15:31:06 MODULE DATA05/05/16 15:31:06 SN:01779 Rev:00505/05/16 15:31:06 Adj:5/15/2006 at AP by ECSFAIL 05/05/16 15:31:07 Execute sweep: F:\ATS 2 SYSTEM CHECK\Anl\Sig-Path.at27Failed Upper 0, Lower 2, Timeouts 0, UnRegulated 0, BadData 0Gen.Ampl A(Vrms), Anlr.Ampl(V), Anlr.Ampl(V)1.99991362, 0.0055625(<1.9), 0.0055625(<1.9)
Tek TDS784A CPU board dsyVGARamdacRegMemfailure [SOLVED] - Page 1
Forum section: electronics / repair

author: Jwalling
author_rank: Unknown
timestamp: May 03, 2016, 06:45:09 pm
content: Working on another TDS784A. CPU fails self test with:Code:"Sat 04-30-;6 02:46:21 ERROR: diagnostic test failure, dsyVGARamdacRegMem, table index= 1b8, actual data = 6 expected = 7, , failure in ramdacPalmem";"""Sat 04-30-;6 03:10:05 ERROR: diagnostic test failure, dsyVGARamdacRegMem, table index= 1c9, actual data = 16 expected = 36, , failure in ramdacPalmem";"Sat 04-30-;6 03:28:56 ERROR: diagnostic test failure, dsyVGARamdacRegMem, table index= 214, actual data = b expected = 2b, , failure in ramdacPalmem""Sat 04-30-;6 03:38:22 ERROR: diagnostic test failure, dsyVGARamdacRegMem, table index= 185, actual data = 1a expected = 3a, , failure in ramdacPalmem""Sat 04-30-;6 03:57:14 ERROR: diagnostic test failure, dsyVGARamdacRegMem, table index= 5, actual data = 32 expected = 3a, , failure in ramdacPalmem"Failure turned out to be an Analog Devices ADV471KP35 RAMDAC on the CPU board in location U190, a 44 lead PLCC. I scavenged the chip from a TDS544A CPU board I had laying around.Board now passes.Jay

author: nctnico
author_rank: Super Contributor
timestamp: May 03, 2016, 08:10:37 pm
content: Good job!These kind of problems are hard to track down!

author: Jwalling
author_rank: Unknown
timestamp: May 03, 2016, 09:45:39 pm
content: Quote from: nctnico on May 03, 2016, 08:10:37 pmThanks. It'd be a LOT easier if Tektronix and Keysight/Agilent would give up the schematics for these old scopes like LECROY has done!(Hint hint) if they read these boards. I know that Daniel from Keysight does; is there a Tek representative in the house?It's not like there could be much super-secret IP left in these units.Jay

author: casinada
author_rank: Frequent Contributor
timestamp: May 03, 2016, 11:44:04 pm
content: If I'm not mistaken Alan a.k.a "W2AEW" works for Tektronix. He might have some inside connections. Also the Tektronix Yahoo groups is another place with some ex Tektronix employees but it is dedicated mainly to the old glory days of analog scopes.
Siglent SDS1062CM Bricked - Page 1
Forum section: electronics / repair

author: tecnofreitas
author_rank: Newbie
timestamp: May 03, 2016, 09:00:13 pm
content: Hello guys . I wonder if it is to recover the Siglent oscilloscope Which was flashed with the wrong firmware. After the update , the oscilloscope connects with the white screen . Thank you!
Runcam 2 unknown chips. - Page 1
Forum section: electronics / repair

author: Ejyryla
author_rank: Newbie
timestamp: May 03, 2016, 10:31:13 am
content: Hi. I found from my runcam 2 camera pcb 2 burned chips. Does anyone know what kind of chips these are and is there any datasheets available to these ships.see attachments.Br Esa

author: David97
author_rank: Contributor
timestamp: May 03, 2016, 11:19:08 am
content: Judging by all those inductors around it it's some switchmode controller. Cant say what one tho

author: amyk
author_rank: Super Contributor
timestamp: May 04, 2016, 11:04:19 am
content: Richtek RT9992, first Google result for "ES 1B" "QFN32"

author: Ejyryla
author_rank: Newbie
timestamp: May 04, 2016, 11:54:35 am
content: Thanks a lot for answers
Help needed: HP4194A  - Page 1
Forum section: electronics / repair

author: ansgar96
author_rank: Newbie
timestamp: May 03, 2016, 08:08:06 pm
content: Hey everybody,I've just got a HP4194A Impedance/Gain-Phase Analyzer out of the scrap container from my university.It powers on and after some time playing with it I think the Gain-Phase section is working.My problem is that the impedance path makes problems.It shows "Bridge Unbalanced" when the measuring bridge is connected to te terminals and "AC current overflow".Have anyone ideas what the problem could be and for what I should look at?If any further information are required I will do my best to provide them.Best regards from GermanyAnsgar

author: MadTux
author_rank: Frequent Contributor
timestamp: May 03, 2016, 08:35:57 pm
content: Quite crazy what people throw out these days.Anyway, first get the manual from here:http://literature.cdn.keysight.com/litweb/pdf/04194-90011.pdf?id=611662Bad news, since it seems to be a HP instrument which has no schematics, only the stupid "contact service center" comment in it, on page 437-438But you could still check the power supply, since that is a common failure in all sorts of instruments. Also check the circuit close to the inputs/outputs, because students usually do all sorts of stupid things with them.Update, I found service manual with schematics, happy fault searching and fixing:http://cp.literature.agilent.com/litweb/pdf/04194-90100.pdf#page=2&zoom=auto,0,480For a few $$$, artek has even better manuals:http://artekmanuals.com/manuals/hp-manuals/
Replacement Light sensor - Page 1
Forum section: electronics / repair

author: J.Xerneas
author_rank: Contributor
timestamp: May 01, 2016, 10:43:06 pm
content: I have a light sensor I need to replace for a car lighting system. I can't get replacement from the manufacturer and I can't find any info on the sensor myself. It is a silver canister with the numbers "21K1383 9524" on it, It also has a glass top on it and there are 2 surface mount resistors in it with the values "225" and "222" on them. I can't take a picture of it because my cheap camera won't focus on it. If anyone knows where to look to find this it would be greatly appreciated.

author: uncle_bob
author_rank: Unknown
timestamp: May 01, 2016, 11:52:24 pm
content: HiMake / model / year of car might be helpful if it came as part of the car when new. If it's an aftermarket add on, brand and model of the add on would go a long way.Bob

author: PaulAm
author_rank: Frequent Contributor
timestamp: May 02, 2016, 11:39:04 pm
content: For that, a junkyard would be your best option, or possibly ebay. Old modules and sensors show up once in a while.It's almost antique

author: uncle_bob
author_rank: Unknown
timestamp: May 03, 2016, 12:43:24 am
content: Quote from: PaulAm on May 02, 2016, 11:39:04 pmHi.... let's see ... when't the next car show in Carlisle ... hmm ....Your only chance is auto salvage. That part is well past "old enough to vote" and now headed into middle age.Bob
Dispensing needles - Page 1
Forum section: electronics / repair

author: akis
author_rank: Frequent Contributor
timestamp: April 28, 2016, 07:27:31 am
content: I am looking for a needle to put at the end of a syringe, or at the end of a squeeze-able bottle, length about 8cm=12cm (3"-4") small diameter (hence needle, not straw), but it must be plastic, blunt, and flexible. I was thinking max 2mm outside diameter. Can't find anything like that on Amazon but my search skills aren't that great.

author: akis
author_rank: Frequent Contributor
timestamp: May 01, 2016, 09:24:36 am
content: OK I know what I want, but I cannot find it easily.Know the WD40 cans that have a very thin piece of dispensing tube stuck to the side? This is the exact tube I need. It has the right length, diameter and rigidness. Short of re-purposing it from old WD40 cans I have no idea where to get it from. Any ideas?

author: tautech
author_rank: Super Contributor
timestamp: May 01, 2016, 09:46:20 am
content: Just wondering if a very small diameter PVC air line tubing is what you need?

author: akis
author_rank: Frequent Contributor
timestamp: May 01, 2016, 10:20:30 am
content: The smallest I can see is like 5mm external diameter. I need something like a needle really, like 2mm external max.

author: tautech
author_rank: Super Contributor
timestamp: May 01, 2016, 10:34:34 am
content: Quote from: akis on May 01, 2016, 09:24:36 amAerosol tubes that I've just measured are 2.1 -2.7mm so something like this might do the trick for you:http://nz.rs-online.com/web/p/flexible-tubes/3139454/

author: rolycat
author_rank: Super Contributor
timestamp: May 01, 2016, 11:00:59 am
content: Quote from: tautech on May 01, 2016, 10:34:34 amTygon is very flexible, so I suspect this doesn't match the OP's requirement for rigidity.These might fit the bill:Sold by fishing tackle suppliers.A pack of 10 tubes is around £1.49, for examplehere.

author: akis
author_rank: Frequent Contributor
timestamp: May 01, 2016, 09:46:40 pm
content: I ordered one thanks.

author: john_p_wi
author_rank: Regular Contributor
timestamp: May 02, 2016, 09:50:33 pm
content: We use these in industry all of the time, just a quick search to give you an idea:http://www.amazon.com/PTFE-Needle-Gauge-Polyethylene-Length/dp/B007I87UGY/ref=sr_1_1?s=industrial&ie=UTF8&qid=1462225626&sr=1-1&refinements=p_n_feature_seven_browse-bin%3A5485644011
Star Wars arcade machine - no EHT on projection CRTs - Page 1
Forum section: electronics / repair

author: Circlotron
author_rank: Super Contributor
timestamp: May 02, 2016, 09:49:54 am
content: We have an old Star Wars Trilogy arcade machine that has 3 projection CRTs and for the first few months it worked great then one day it had a black screen. I figured there might be no EHT on the CRTs, and waving a CRO probe near the horizontal output transformer didn't pick up anything. I imagine the drive signal to the horizontal output stage has quit. We have no schematics at all. Could anyone help here?

author: SeanB
author_rank: Super Contributor
timestamp: May 02, 2016, 11:25:07 am
content: I would guess that the horizontal transistor has died, probably from either dry joints on the LOPT, flyback tuning capacitor or the power supply. Replace with only the exact device, and resolder all the joints in the LOPT area, and check the capacitors and the resistors there, along with the joints on the drive transformer. Power supply voltages should be marked on the PCB from the power supply. Check them all, there is a similar SMPS there with the same issues.As well clean the EHT cables and the splitter, so that there is no dust to cause a flashover which will kill the new transistor.
Roberts MP-43 DAB Radio - Page 1
Forum section: electronics / repair

author: rahandford
author_rank: Regular Contributor
timestamp: May 02, 2016, 06:52:50 am
content: Does anyone have any experience with these units?This unit will not receive (DAB or FM).Trying to check power rails but have no idea what they should be!The unit is based on the KINO 2 chip that is in a plug-in module.Cant even find a schematic or datasheet.Any help would be much appreciated.

author: JFJ
author_rank: Regular Contributor
timestamp: May 02, 2016, 09:05:43 am
content: Have you tried a System Reset?The reset procedure can be found on page 45 of the user guide:http://www.manualslib.com/manual/141409/Roberts-Mp-43.html?page=47#manual
remote operated slide switch - Page 1
Forum section: electronics / repair

author: BurningTantalum
author_rank: Frequent Contributor
timestamp: May 01, 2016, 07:28:37 am
content: I have just acquired a nice Denon audio amp, all 21 kg of it, for a nominal fee. The fault appeared to be that the input selection was stuck on 'CD'.This was soon traced to a broken control on the front panel. This operates a slide switch mounted on the pre-amp PCB remotely via a steel tape in a plastic guide- a sort of Bowden cable.I have managed to repair the item but could not locate such a thing with various suppliers, mainly because I don't know what it is called. Does anyone know what this item is known as?Regards, BT

author: German_EE
author_rank: Super Contributor
timestamp: May 01, 2016, 08:28:28 am
content: This will be a custom part manufactured for Denon so your only source for a replacement are Denon themselves or the various parts warehouses scattered around the world. What's it called? I would go with cable controlled slide switch and leave it at that.One thought occurred to me. If that switch dies again then replace it with DPDT relays at the PCB end and a rotary switch on the front panel.

author: uncle_bob
author_rank: Unknown
timestamp: May 01, 2016, 02:20:32 pm
content: HiThat's a highly custom part. Both the cable *and* the switch are unusual. If you want to keep the amp running, stay on the lookout for another one to act as a "parts donor".Bob

author: BurningTantalum
author_rank: Frequent Contributor
timestamp: May 02, 2016, 02:12:11 am
content: Thanks both of you.The repair was very successful; better than new probably, so I hope that I will not have to revisit it. I could not find any term to insert in Google that would bring anything up !I bought the amp a while ago for a few dollars. The seller told me that it had just stopped working one day. I powered it up and checked the output, which showed a few millivolts. A wet finger on a phono lead gave a few volts AC with the volume control working so I connected a couple of cheap speakers and... it has worked fine since.The annoying thing was that he told me that he had sold a pair of speakers just before I arrived. From his description (he couldn't remember the name of them and I didn't enlighten him) they MUST have been Allison Ones. I'm trying not to think about why I went to the newsagents before going to the yard sale...BT
Looking for Information on Motorola ZC68115 - Page 1
Forum section: electronics / repair

author: unclebob
author_rank: Contributor
timestamp: May 01, 2016, 05:46:16 pm
content: Hello folks,I am repairing an old Schneider Euro PC (http://www.classiccomputer.org/ams/scheuropc.htm). The NiCd backup battery has leaked over the mainboard and everything looked pretty crusty but at least I got it cleaned up a bit and replaced the missing traces of the board with wires. I also replaced a graphics RAM which was dead. Now I am facing a real problem. The keyboard controller has a problem and does not recognize all keys (without Enter, DOS is not that interesting). The keystrokes show up at the pins of the chip but not all of them are recognized so I think al least one port of the controller is gone. The chip ist marked as Motorola ZC68115P. Does anybody have information about this chip? Could it be a custom mask programmed 6800? Any chance of getting a spare part?All the best,Christian
Heathkit O-11 vacuum tube oscilloscope restoration - Page 1
Forum section: electronics / repair

author: Shock
author_rank: Super Contributor
timestamp: April 28, 2016, 12:05:53 pm
content: Some good restoration tips, first video is the checkout, second video is the actual restoration.

author: med6753
author_rank: Super Contributor
timestamp: April 30, 2016, 09:40:36 pm
content: Brings back memories. My first scope was my Father's O-10 which is 99% identical to the O-11. I think the only difference was there was no fuse on the primary.
ATTEN F2700C / DIGITECH QT-2202, Repair / Review - Page 1
Forum section: electronics / repair

author: Moshly
author_rank: Regular Contributor
timestamp: July 21, 2013, 01:36:11 am
content: Hi, guys & girlsI purchased a DIGITECH QT-2202 (ATTEN F2700C) frequency counter from Jaycar a few years ago.Payed the full $200 AUD, a month later Jaycar reduced the price to $160I only used it a few times in a 2 year period, probably less than 8 hours in total.Then when i need it most, no go, the display is frozen on a single digitSwitching it off an on again just made it display random segments on the first digit.After probing about, i found that the 13MHz TXCO was not oscillating.Actually it had a temperature related fault, warm it up a bit and it starts working.Searching Ebay i found these 26Mhz TXCO's for only $2 AUD each ->eBay auction: #http://www.ebay.com.au/itm/TCXO-26-MHz-SMD-Toyocom-/121130161455?pt=LH_DefaultDomain_77So after receiving a few, i made this little replacement PCB.Firstly the TXCO is 3.3V so i need a 3.3V regulator.Then i need a transistor buffer to give enough level to drive the 74HC74.The 74HC74 divides the 26Mhz in half to give 13MHz.Originally using my FE-5680A as a reference, and once the rubidium standard and the TXCO in the counter had stabilized, the counter would flip between 10,000,034Hz and 10,000,031Hz every 2 seconds.Now, with my reference installed, it displays 10,000,000Hz or 9,999,999HzSo, now for a quick review of the counter.1, The push buttons are crappy, had to fix one that the little U shaped flipper spring had snapped. Replaced it with a bent paper clip2, The 7 segment display is screwed up when displaying the 1 digit, the LEDs are lit wrong, segments E & F instead of C & B3, The BNC socket on the back is a 13MHz output, not a 10MHz reference inputuseless.4, The counter is not very sensitive and easily gets confused by noisy input signals.5, The ATTEN version is now available for around $100 USDSo overall it is ok (if it doesn't fail), but i will think twice before looking at any test gear from ATTEN & Jaycar/DIGITECH again.

author: saturation
author_rank: Super Contributor
timestamp: July 21, 2013, 01:00:11 pm
content: Sorry to hear; I would do the same, Atten is not in my list of preferred brands.Consider a used Racal-Dana 1991 or similar series, and snatch it up when it appears. It was a UK company so I presume the meters are easier to find than those of HP.http://www.ebay.co.uk/itm/RACAL-DANA-1998-FREQUENCY-COUNTER-10Hz-1-3GHz-WITH-OPTIONS-04B-10-/151071966348?pt=UK_BOI_Electrical_Test_Measurement_Equipment_ET&hash=item232c97448c

author: Hydrawerk
author_rank: Super Contributor
timestamp: April 28, 2016, 10:54:34 pm
content: http://www.radiomuseum.org/r/hungchang_multifunction_counter_hc.htmlATTEN F2700C is probably heavily inspired by a 1980's Hung Chang frequency counter HC-F1000.
Help finding Circuit Board for Sony SRS-BTX500 - Page 1
Forum section: electronics / repair

author: RockyJ
author_rank: Newbie
timestamp: April 28, 2016, 06:50:00 pm
content: Greetings, I dropped my BTX500 and thereafter was able to run the volume down, but not back up. I disassembled and have troubleshot it down to the Top Key BD circuit card. There are a few (part?) numbers on the card ("SR7739" , "271-ST0220-B10X0" , "S711-3887-1E20") none of which produced results in my Google search. It would be an easy fix if I could just find a distributor and buy the board. If anyone could help me locate one I'd be very grateful. I'd hate to shell out the coin to have an Sony authorized repair center do it for me. I'll attach a photo of the board I'm referring to.
Korad KA3005P Low Current Startup Problem - Page 1
Forum section: electronics / repair

author: hgg
author_rank: Frequent Contributor
timestamp: May 12, 2016, 12:02:37 pm
content: Hi,Is this normal ??https://youtu.be/9DwytzdpQOcYou cannot switch on the output with a 17mA current limit.With 18mA it ramps up. I guess the output capacitors, but zero output with anything less.Any ideas or someone else with a similar problem?Thanks.

author: ProBang2
author_rank: Frequent Contributor
timestamp: May 12, 2016, 01:20:44 pm
content: Hello.Your video is marked as "private", hence not visible.I can enable the output of my KA3005P even with 1 mA current set.Output checked with DMM: ~ 0.8 mA (regard the burden voltage)Which kind is your load?Do you are using the normal "current control" (so there is no problem)?Or the specific current limit setting ("OCP")?The OCP is supposed to shut down the output if the given limit is reached (even with a short spike).

author: hgg
author_rank: Frequent Contributor
timestamp: May 12, 2016, 01:25:58 pm
content: Oops, it should be ok now. Can you check?No OCP or OVP enabled.It does the same with a load and without.So, there must be some kind of damage.It used to start up with 1mA as well.

author: ProBang2
author_rank: Frequent Contributor
timestamp: May 12, 2016, 01:43:51 pm
content: It seems, it does not matter if a load is connected.Starting output at 1 mA, at 17 mA and every value inbetween.Tested: Open circuit, DMM (measuring mA) and with a resistive load (a simple lightbulb).I have no clue, why your PSU does not start?BTW: Your video is visible now. Right now seen it. Strange ...

author: hgg
author_rank: Frequent Contributor
timestamp: May 12, 2016, 01:47:37 pm
content: Hmmm, I might have to open it to see if there is something obvious.

author: Kleinstein
author_rank: Super Contributor
timestamp: May 12, 2016, 06:14:54 pm
content: It might be a rather offset of about 17,5 mA, so anything less than 18 mA set might actually be a 0 mA (or negaitve) current limit.As a test, one could measure the maximum current with low settings (e.g. 18 mA , 20 mA).

author: hgg
author_rank: Frequent Contributor
timestamp: May 12, 2016, 06:39:08 pm
content: When I measure the current with the multimeter its the same as the value shown on the Korad display.Just played with its current calibration and now it is able to start from 3mA.Still cannot do 2 or 1mA. Strange.
Agilent E4430B signal generator AM modulation is funny - Page 1
Forum section: electronics / repair

author: ErnieEngineer
author_rank: Contributor
timestamp: April 28, 2016, 02:31:18 am
content: Just purchased a E4430B and decided to do a quick check with the AM modulation. It looks weird, with extra images!NOTE: the picture is for when I used internal modulation, but external modulation is the same (1Vpp AC coupled, 50kHz)Is there any way to fix/adjust this?My other generator (N9310A) is shown for comparison.

author: VK5RC
author_rank: Unknown
timestamp: April 28, 2016, 02:36:04 am
content: Is it just clipping? Does it go ok at say 80% modulation? At 100% aren't you only a whisker away from over modulation?

author: ErnieEngineer
author_rank: Contributor
timestamp: April 28, 2016, 02:46:01 am
content: Excellent point! When I switched to 10% it looks perfect. Why would the other generator not have this at 100% tho?It looks just as ugly at 80%, anything above 20% really.

author: VK5RC
author_rank: Unknown
timestamp: April 28, 2016, 04:54:35 am
content: Can you see the waveform on a scope, and see if the 50% as 'dialed in" is correct?Mixers are the' devils work'. If you know what I mean, very difficult to get it right re harmonic suppression, 3 order intercept etc.Hopefully some of the serious rf guys will chip in shortly, best of luck.
Oscilloscope HP 54112D error message - Page 1
Forum section: electronics / repair

author: ooorobertoooPL
author_rank: Newbie
timestamp: April 24, 2016, 07:16:49 pm
content: Hi, I bought an old HP 54112D oscilloscope at a garage sale. Begins the test and displays the error "system error ZERO DIVIDE 01493CH". On board processor are two empty U14 and U31 memory slots, the questions I have two slots must be empty, or not?

author: wn1fju
author_rank: Frequent Contributor
timestamp: April 24, 2016, 10:16:00 pm
content: My working 54112D has two empty sockets just like your unit.If you haven't already, you might try the two-key power up where you hold down the top and bottom softkeys on the right edge of the display whilepowering the unit.

author: ooorobertoooPL
author_rank: Newbie
timestamp: April 25, 2016, 06:00:29 am
content: I tried the bottom soft key, and sopower-up self test in progressLast loop completed: 1..12..40..50..59.60.61 end blac screnn , nothing happens ,corrupted memory ??

author: jitter
author_rank: Frequent Contributor
timestamp: April 26, 2016, 07:45:43 pm
content: Are those the so called "low cost" IC sockets with spring contacts (as opposed to the "high quality" type with the turned pins)?If so, I would take out and reseat every IC in such a socket one by one to break any oxide. Worth a try as it's free...

author: ooorobertoooPL
author_rank: Newbie
timestamp: April 27, 2016, 06:55:14 pm
content: I checked all the checkpoints , all the connections, all the elements and everything seems to be okay only U51. And of the service book , according to the table U51 is powered by 5V for me is 15 V, during the test DAC service should send different values and I have all the time value -9.99v . This value must be 5v or 15 v ??
LCD (or Controler Failure) - Page 1
Forum section: electronics / repair

author: kolbep
author_rank: Frequent Contributor
timestamp: May 02, 2016, 10:30:04 am
content: Hi.I was just wondering, does this fault look like the LCD itself is faulty,or could it be the board that takes the Video Signal, and sends it to the LCD?My Guess is the LCD... Because the defect is a funny oval shape, and 1 section of the LCD is dead (Which corresponds to the 1 set of ribbon cables from the onboard controller (on the LCD itself).The Backlight is powering up fine.They are going to fly replacement parts in for me, but just want to make sure.Thanks

author: bktemp
author_rank: Super Contributor
timestamp: May 02, 2016, 12:43:54 pm
content: My guess what happened:One driver chip on the left failed and is shorting one of the analogue voltage rails. This affects all other drivers, therefore the LCD sees a DC voltage (LCDs don't like DC) and displays strange images. The oval shape is most likely caused by the DC voltage slowly destroing the liquid crystals and therefore changing their characteristics. The non uniform pressure applied the LCD due to mounting of the display creates the patterns.I have seen even more funny/interesting patterns on LCDs when shutting them down but keeping the backlight on without discharging the analogue voltages.
Teardown, Repair & Experiments of an Agilent E7495B 2.7GHz Base Statio Tester - Page 1
Forum section: electronics / repair

author: Hugoneus
author_rank: Frequent Contributor
timestamp: April 19, 2016, 06:19:07 pm
content: You can watch the video here: [23 Minutes]youtu.be/IWW2_VzIEXgMore videos at The Signal Path:http://www.TheSignalPath.com

author: PA0PBZ
author_rank: Super Contributor
timestamp: April 19, 2016, 08:00:47 pm
content: Well, that was ugly. Looks like they took the necessary parts from the N1996a and somehow managed to put in in that housingAnyway, if you want to enable some more options have a look here:https://www.eevblog.com/forum/testgear/agilent-e7495-linux-root-account/msg615695/#msg615695

author: Towger
author_rank: Super Contributor
timestamp: April 19, 2016, 08:02:10 pm
content: Ribbons galore.I wonder what Bill and Dave would have said if they saw the inside of that unit being developed.

author: TheSteve
author_rank: Unknown
timestamp: April 19, 2016, 08:09:40 pm
content: Pretty weird indeed, especially considering his big brother the N1996A is so neat and tidy. I think they would be much more valuable if the source frequency didn't start at 375 MHz.Shahriar - please help with my PM if possible, you're my only hope!

author: AF6LJ
author_rank: Unknown
timestamp: April 19, 2016, 08:37:27 pm
content: Wow..Talk about five pounds of compost in a four pound bag...That is almost as bad as my IFR FM/AM 1000S

author: Hugoneus
author_rank: Frequent Contributor
timestamp: April 24, 2016, 03:10:31 am
content: Quote from: PA0PBZ on April 19, 2016, 08:00:47 pmThank you!

author: AF6LJ
author_rank: Unknown
timestamp: April 24, 2016, 03:17:23 am
content: Good video thanks.

author: mmagin
author_rank: Frequent Contributor
timestamp: April 26, 2016, 11:22:44 pm
content: Thanks for the video, I have one of these or a very similar model -- It also seems to be a dead power supply.Looks like it may have some display damage, but until I light up the display, I'm not sure.Sadly it has some other physical damage to the RF in/out I may have to improvise a fix for out of semi-rigid coax and decent connectors. (Or see if Keysight is only asking reasonable prices for the part.)

author: TheSteve
author_rank: Unknown
timestamp: April 27, 2016, 04:05:47 am
content: Quote from: mmagin on April 26, 2016, 11:22:44 pmI've seen mention that some people have had the LCD screen start to de-laminate. Post up some pictures and maybe we can offer some advice on how to handle the damaged RF in/out connector.
Lifted pad - Page 1
Forum section: electronics / repair

author: daniel123
author_rank: Regular Contributor
timestamp: April 25, 2016, 09:06:37 pm
content: How do I repair a lifted pad on a through hole pcb board with ready available martials no solder paste available at the ready. So if anyone has suggestions please give me some. Thanks

author: GreyWoolfe
author_rank: Unknown
timestamp: April 25, 2016, 09:33:06 pm
content: You could try a good superglue like Loc-Tite professional. I have just started using it and it works well. I haven't used it to glue solder pads but it should work fine. By the way, try not to get it in the hole

author: BMack
author_rank: Regular Contributor
timestamp: April 26, 2016, 12:54:58 am
content: Post a picture, there are several ways to do it and it's difficult to recommend a solution without seeing the extent of the damage and what's surrounding the lifted pad.

author: ovnr
author_rank: Frequent Contributor
timestamp: April 26, 2016, 01:07:57 am
content: Quote from: GreyWoolfe on April 25, 2016, 09:33:06 pmTerrible idea. Superglue is not at all stable at soldering temperatures, and will just stink up the room.If you're just looking to glue it down, my suggestion is to contemplate the fact that (FR4) PCBs are a glass-fiber laminate bonded withepoxy.

author: macboy
author_rank: Super Contributor
timestamp: April 26, 2016, 02:17:11 pm
content: Quote from: ovnr on April 26, 2016, 01:07:57 amCompletely agree with both points. Superglue can make nasty harmful vapors at high temperatures. I don't recommend.Cured epoxy is heat proof to soldering temperatures, and in fact the heat should make it cure faster if not 100% cured yet. It will become plastic/soft at those temperatures, so the pad may be delicate until cooled down.

author: SeanB
author_rank: Super Contributor
timestamp: April 26, 2016, 04:09:34 pm
content: Single pad just solder the part, then clean with IPa and acetone, then apply a single drop of superglue to the edge to hold it in place further.
Apple MagSafe 820-2627-A - Page 1
Forum section: electronics / repair

author: Elrod
author_rank: Contributor
timestamp: April 25, 2016, 01:56:13 pm
content: I recently had to repair my daughters aging Macbook(A1342). It would no longer charge so I opened it up and found a burned SMD package on the small MagSafe PCB where the power enters. These are easily available online so I ordered one but was also curious what was on the small PCB. There are schematics available for the main logic board of the Macbook but I could not find a schematic for this small PCB anywhere. I have drawn out what I found and will post here in the hopes that someone else might find it useful. The part number on the PCB is 820-2627-A.

author: Wirehead
author_rank: Regular Contributor
timestamp: April 25, 2016, 07:13:31 pm
content: How about a picture of the burnt area

author: Elrod
author_rank: Contributor
timestamp: April 26, 2016, 12:14:45 am
content: Quote from: Wirehead on April 25, 2016, 07:13:31 pmOk. No problem. D1 had burned/shorted. I removed it to so that I could determine what trace went where with my ohmmeter. I still had trouble because I kept having low resistance readings to the chassis ground. Finally determined that the PCB was charred beneath D1. I had to dig out the charred area so that I could continue continuity checks without the leakage path through the PCB. So that's why there is a hole there.

author: Wirehead
author_rank: Regular Contributor
timestamp: April 26, 2016, 05:12:03 am
content: The big question is, why has that diode gone up in smoke? If it failed by itself, you could hack up something to work around the charred area. If it's "upstream" you might run in to the same issue again. So make sure you check that as well. Cheap fix would be to snag one of these board from ebay or the likes.
DSO6000 schematic  - Page 1
Forum section: electronics / repair

author: surachoke
author_rank: Newbie
timestamp: April 25, 2016, 05:00:02 pm
content: I just bought the DSO6014L 1U oscilloscope from the Ebay.The lan connection seems not to be established as the Keysight IO lib. can't find this instrument.However, the GPIB and USB on this scope operate properly and Keysight IO can recognise it on both interface.I need the schematic for this scope to check on the RC component on the lan port.Could anyone know how to get this schematic?I did try on the service manual of the DSO6000 but can't find any clue for the schematic.