hybridfree/eevblog-posts huggingface dataset:
Sony Gtk-Xb7 main board dc-dc controller ic component identification  - Page 1
Forum section: electronics / repair

author: jimbit22
author_rank: Newbie
timestamp: May 28, 2018, 09:13:08 pm
content: Hi everyone.I'm trying to repair the main board of gtk xb7 Bluetooth speaker.The faulty component is a buck dcdc converter but I can't identify it in order to get a replacement.The writing on the chip says 624b1 p3490It is responsible for providing the 5v or 3.3v rail for the main board.Anyone knows the part number or can suggest a drop in replacement?

author: jimbit22
author_rank: Newbie
timestamp: May 30, 2018, 08:48:56 am
content: Does anyone knows who this manufacturer is? I've been looking at all the sites that have the logos and I'm not able to find a match yet..The board has two of these switching regulators and this is the good one. The other one has a hole that let out the magic smoke.Also looking through the pin outs of similar products i haven't found any pin compatible the vin on this thing is 34v and supply current probably over 2.5A.Probable pin out:Pin1 mosfet oscillatorPin2 vinPin3 swPin4 Vsense or agndPin5 enablePin6? (has an r/c network)Pin7 Vsense?Pin8? (has voltage divider)

author: vinni-tt
author_rank: Newbie
timestamp: June 07, 2018, 05:22:17 pm
content: Hi were you able to figure this out ??I have few of those boards with no power i tried changing those ics and still no power.What else could go bad ?Thank you

author: spagbol
author_rank: Newbie
timestamp: August 11, 2018, 02:36:28 pm
content: Hi, just received one of these units, there's a guy posting an ad on Ebay offering replacement components, from what he's saying if there is no power from the chip or the diode next to it then he can supply an alternative .. has anyone tried this?

author: jimbit22
author_rank: Newbie
timestamp: September 05, 2018, 01:43:03 pm
content: First you should check that the +36v power supply is working ok. it has a PSON pin that you can bridge to ground. be careful tho..Second check the +3.3v line on the stm microcontroller for any shorts. You can find the pin out on the datasheet.I still cant find the ic so i don't have any more troubleshooting info to give..I know for a fact that my brothers speaker burned out by being left ON for 3-6 months straight..EDIT:So after looking closer, i measured the diode next to the burned dc dc converter and it failed short circuit and took the dc dc converter with it..I checked all the rails and nothing else seems shorted or bad.Can anyone identify the manufacturer of the dc dc converter? i looked everywhere..

author: jimbit22
author_rank: Newbie
timestamp: October 23, 2018, 12:27:00 pm
content: Part found:EUP3490Manufacturer: EUTECHI leave the info here for the next who needs it..
HMI repair and illogical zener configuration  - Page 1
Forum section: electronics / repair

author: mnt22
author_rank: Contributor
timestamp: October 22, 2018, 07:10:12 pm
content: Hi everyone, this HMI flickered then the magic smoke come from it.I track the input voltage on the pcb all good to the td1501sadj buck converter output, what confused me is the burned zener diode with zero ohm resistors!, and I found burned chip witch i can't find datasheet for it (U6) (1102A/AAC?),I need some help finding datasheet for it and (U9) (gh158/502MI) also I wonder why and how zener with zero ohm!.Thanks everyone in advance

author: Paul Moir
author_rank: Frequent Contributor
timestamp: October 22, 2018, 07:33:34 pm
content: It looks like the 0 ohm resistor disconnects the power supply from the rest of the circuit. It may have been intended for troubleshooting, or a place for a flameproof resistor fuse. The zener diode was to protect against over voltage from the supply but it burnt and failed open. Likely that other chip died next.There could be more carnage on that railThere may be more damaged devices that are supplied by that power supply.

author: mnt22
author_rank: Contributor
timestamp: October 22, 2018, 08:03:09 pm
content: Unfortunately the zener diode failed to 4 ohms and wreaked havoc on the chips

author: floobydust
author_rank: Super Contributor
timestamp: October 22, 2018, 09:15:15 pm
content: PossiblySCM1102APWM controller, it needs an external mosfet switch.AAT1102 boost-converter SMT marking code is 1102 MAAC, OP has 1102 AACB.

author: mnt22
author_rank: Contributor
timestamp: October 23, 2018, 05:37:03 am
content: it turns out U6 is AAT1102 (ADVANCED PWM DC-DC CONVERTER WITH INTERNAL SWITCH AND SOFT-START)as MULTIPLE-OUTPUT TFT LCD POWER SUPPLY
HP laptop logic board repair - G5/6 - R18D - Page 1
Forum section: electronics / repair

author: mrme01
author_rank: Newbie
timestamp: October 23, 2018, 04:24:55 am
content: Hey folks, I've got a HP G series laptop, with an R18D motherboard that doesn't power up correctly, I have the service PDF, I did have the boardview, but I have since lost it and finding it again online has been rather unsuccessful with paywalls. I can upload the document and send it if you would like to help me?If this is not the right place to get this guidance, please forward me onto a more relevant arena.It does not seem to power up the screen, I did have some instant power off issues before retirement. I have some dead laptop motherboards I can scavenge for parts.I am yet to measure voltages. Thou shalt check voltages. Any specific areas to focus on?Where can I upload the service manual?Thank you for reading, MrMe01
zebra gk420d thermal printer - Page 1
Forum section: electronics / repair

author: Rolnik
author_rank: Newbie
timestamp: October 22, 2018, 11:28:52 am
content: HelloI am trying to fix the printer, everything except the stepper motor driver TB62209FG (http://pdf1.alldatasheet.com/datasheet-pdf/view/137000/TOSHIBA/TB62209FG.html) works. Referring to its datasheet the TSD protection is active because its outputing 5v to pin 19-PROTECT, I've purchase few more of this IC's and solder two of them and they also outputing 5v on pin 19 and I can't understand why, can someone help me ?
Help to identify texas Instruments chip - Page 1
Forum section: electronics / repair

author: HugoPT
author_rank: Contributor
timestamp: October 22, 2018, 09:06:22 am
content: Hello folksToday I'm trying to repair a board that burns a MOSFET and a chip that i'm not able to identify properly.The circuit controls two mosfets to drive a solenoid. Somehow the MOSFET Q1 gets shorted, the resistor R52 is burned has expected since there was a direct short for a long time and the chip U10 also gets damage.My problem is to identify the chip U10. It appears to be a texas Intruments part but I cannot find any info with just HB04. Could this be a 7404 chip?From my circuit analyses it could act like a buffer to simply invert the control signal to drive the mosfet.I'm also not able to identify the mosfet Q1 with reference DAQX.The mosfet must handle 24V to move the solenoid and I think it could be a N channel.The voltage at gate appears to be 5V to turn on the mosfet since the VCC of the chip U10 is also 5V.Does anybody can help me identifying this parts?Thanks for your time

author: kjr18
author_rank: Regular Contributor
timestamp: October 22, 2018, 09:26:53 am
content: It might bethis

author: coromonadalix
author_rank: Super Contributor
timestamp: October 22, 2018, 10:15:49 am
content: I would say the same ?

author: HugoPT
author_rank: Contributor
timestamp: October 22, 2018, 11:16:02 am
content: Thanks for fast replyThat confirms my suspicion but there is one thing that is bugging me.The gate of the mosfet that has burn is connected to pin 4 which according to the datasheet is 4Y output but pin 3 apparently is empty which does not match accoring to the pin configuration pin 3 is the input and it must not be empty.It should be connected to one of the control signals.I will desolder the chip to see if there are some hidden tracks below the chip.Thanks for your time
HP 3561A repair - Page 1
Forum section: electronics / repair

author: Floopy
author_rank: Regular Contributor
timestamp: October 21, 2018, 01:36:37 am
content: Hello,I recently acquired a HP 3651A. When I first got it, it didn't want to turn on. After some troubleshooting I replaced a diode package in the power supply (picture attached). It seems to work, but unfortunately the screen is compressed. What could be causing this? Anybody is more familiar with CRT drivers than me. I'm at least 95% sure that the digital display driver is working properly. Anyway probing around, the fast sweep synchronizer signal seems to be what it should be (FSYNC)(The service manual has pictures). The only anomaly I have seen is the LowPdrive (pulse drive) and FSYNC seem to be a little bit out of alignment. (see picture) Usually they are supposed to be alignedIf anybody is interested in what I'm saying, have a look at the service manual.(Start at page 214 for the analogue display)http://www.ko4bb.com/manuals/174.148.87.57/HP_3561A_dynamic_signal_analyzer_service_manual_V2_1983.pdfIf you don't care at least I have some photos! Very nicely built that's for sure!

author: Floopy
author_rank: Regular Contributor
timestamp: October 21, 2018, 01:38:08 am
content: The rest of the pictures

author: SilverSolder
author_rank: Super Contributor
timestamp: October 21, 2018, 04:39:07 am
content: The distorted picture indicates a problem with vertical deflection called "vertical foldolver".Check the output stage that drives the vertical deflection coil - bad solder joints, capacitor deterioration, resistor drift, bad driver IC, etc.Check outhttps://www.repairfaq.org/samnew/tvfaq/tvvfold.htmandhttps://www.repairfaq.org/samnew/tvfaq/tvcovertp.htm...and other vertical deflection articles on that site which look relevant to this repair.

author: Floopy
author_rank: Regular Contributor
timestamp: October 21, 2018, 04:34:58 pm
content: Thank you I needed guidance.
Infrared thermometer DT-380 - Page 1
Forum section: electronics / repair

author: carrascoso
author_rank: Contributor
timestamp: October 21, 2018, 04:21:13 pm
content: Hi all.I own a Chinese infrared thermometer DT-380 (-50ºC - 380ºC).When going to use it did not mark well, and it did not go beyond 50ºC even if it was aimed at a flame, with low temperatures it seems to go well.After removing the eeprom (L24C02B-SI) and erase it, the top of 50ºC was solved, but now it marks three times the actual temperature.I ask if someone has a backup of the eeprom can you provide it to repair this thermometer.Thanks and best regards.
Model 102 battery holder spring contacts - Page 1
Forum section: electronics / repair

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: October 21, 2018, 02:32:09 pm
content: The holder for the 4 AA cells is screwed to the motherboard, I couldn't find a new one like it. Luckily, Keystone still makes the wire springs that (seem to) fit into the plastic!Isn't that cool?https://www.keyelco.com/product-pdf.cfm?p=14216Originally I wanted to harvest the springs from a new holder but they use riveted contacts or sometimes a little metal plate. Not one used this little binocular thingy. Also the 102's pack solders the springs right into the board, no wires. I was also able to get the springs for that although I will have to do some bending.I might never get this thing to work but at least it'll be clean enough.
Anritsu MG3642A Synthesizer Service ... - Page 1
Forum section: electronics / repair

author: saradr
author_rank: Newbie
timestamp: October 26, 2018, 04:24:48 pm
content: Have a nice MG3642A w/no output and error " alt. reference abnormal". Have been unable to find a service manual so far. Might anyone know of a web source? With good 10Mhz alt. ref. unit then shows "rf amplifier level abnormal". I'd like to read theory of design as far as int/ext. freq. reference and P.S. test points before I just tear into it...Thnx
Asus laptop not working - Page 1
Forum section: electronics / repair

author: ivers
author_rank: Newbie
timestamp: October 21, 2018, 08:54:39 am
content: Ooops, remove this please.

author: coromonadalix
author_rank: Super Contributor
timestamp: October 21, 2018, 10:07:07 am
content: The 3r3 part is a choke / coilThe 8 pins soic are maybe some kind of mosfets / switch smps ic's ? check the pinouts if they are many connected together like 3pins + 3pins + maybe 1 or 2 pins for the gate ??and the small square one is maybe an smps controller of some sort ?My 2 cents of guesses
COMTECH EFDATA 10MHz module with OCXO VECTRON C4710 - Page 1
Forum section: electronics / repair

author: Iv3xkv
author_rank: Newbie
timestamp: October 21, 2018, 05:14:59 am
content: I have a nice surplus 10MHz reference generator module dismantled from unknow equipment.It is marked COMTECH EFDATA PL/0014-5 . I would like to test and repair it to reuse.Have someone informations about this module and the connecting scheme of his 8 pole connector?On the module is installed a 10 MHz OCXO VECTRON marked as C4710C1-0021 27318-0061 0822. In the VERITRON web site is available the datasheet of the C4710C1 but it is not clear the meaning of part-number extension (0021 27318-0061 0822) that, I suppose, define the version. Can someone help me to understand detailed specs of this OCXO?Picture of the module at:https://flic.kr/p/2aUHWsGThanksGiuliano IV3XKV
PJN5208 - Page 1
Forum section: electronics / repair

author: lionelkjh
author_rank: Frequent Contributor
timestamp: October 28, 2018, 09:50:39 am
content: Hello; I have a calibrator that I am restarting. The internal batteries to power it were dead. After replacing and loaded, it starts but it shows me "empty memory". The batteries are no longer charged for a very long time, which has resulted in the loss of the 9 measurement plans written in the internal memory of the calibrator. I think that to re-record these erased plans in RAM, it is necessary to use software with an RS232 port. My question is therefore: Would anyone have this software (because the calibrator should be almost 30 years old!), And most importantly, how to connect to the RS232 (because the connector does not correspond to our current computers? Thank you very much for your help because I am in a dead end (even 2 years after my first post on eevblog: I attached the photo)

author: Whales
author_rank: Super Contributor
timestamp: October 28, 2018, 10:01:48 am
content: Post a pic of the RS232 connector and a pic of the insides, we might be able to help better.

author: lionelkjh
author_rank: Frequent Contributor
timestamp: October 28, 2018, 10:07:37 am
content: The RS232 was removed when the batteries were unsoldered because the plug was completely corroded and broken. From memory, the solder plug was similar to a 3.5mm jack socket (photo) .....

author: Whales
author_rank: Super Contributor
timestamp: October 28, 2018, 03:01:30 pm
content: It's not uncommon for UARTs to be done over 3.5mm audio jacks. Three wires (GND, RX, TX) is often enough. If the connector is no-longer there you can bypass it and tap wires onto the PCB yourself.First you will want to grab a multimeter and measure the voltages of each wire compared to a known ground in the unit (whilst it's on). This will tell you which wire is GND and what the signalling voltage levels are (proper RS232 or lower voltage). RX and TX aretypicallyboth held 'high' to a voltage through internal resistors.When it comes to working which way around RX and TX are: often you have to guess. To avoid potential damage put some resistors (eg 1Kohm) in series.
[SOLVED] 5 pin 5V linear regulator identification/compatible replacement - Page 1
Forum section: electronics / repair

author: abyrvalg
author_rank: Frequent Contributor
timestamp: October 20, 2018, 11:38:55 pm
content: Could somebody help me identifying a regulator from year 1995 Jeep Wrangler ECU? Or perhaps just point me to something compatible.Marking says:49365A 403-2MAL2616023M01CS9517JThis regulator supplies a 5V CPU section of the ECU, providing some signal (POWERGOOD to nRESET?) to the supplied CPU.This is a 5-pin TO-220 IC with this pinout (left to right):1 - Vin (car 12V)2 - POWERGOOD, connected to CPU nRST - this is a guess, has an external pullup3 - GND4 - ? - connected only to a big ceramic cap to gnd5 - VoutAll this looks very similar to MIC29301 and brothers, but has a different pinout. If I’ll not find out a pin-compatible ic I’ll use MIC29301 bending it’s legs a bit.Edit: attached an image

author: langwadt
author_rank: Super Contributor
timestamp: October 21, 2018, 12:47:43 am
content: Quote from: abyrvalg on October 20, 2018, 11:38:55 pmhttp://users.tpg.com.au/users/p8king/files/l487.pdf?
looking for modern equivillent for this axial condenser - Page 1
Forum section: electronics / repair

author: clubconsoles
author_rank: Newbie
timestamp: October 20, 2018, 03:02:41 pm
content: it is from a 1939 electronic dice game. It should be shunting a solenoid that pays out coins.I have tested the solenoid and its fine and game has been rewired so no shorts as was the case with the old cloth covered wires!

author: DaJMasta
author_rank: Super Contributor
timestamp: October 20, 2018, 03:10:28 pm
content: It's hard to see from the picture, but a 5 MFD condenser is the same in modern description as a 5 Microfarad (uF) capacitor. I can't tell if under that in the image is a 25V rating, but you just need a similarly rated modern capacitor. Given the use case, probably any electrolytic should do a reasonable job, and going with a more standard value like 4.7uF should be fine as well.

author: clubconsoles
author_rank: Newbie
timestamp: October 20, 2018, 03:22:40 pm
content: many thanks for your reply.thats the best pic i could get.it readsMT400 W. V.25 and there is 6-8 v and 24V DC coming from power pack so i will try your recommendation, thank you!

author: james_s
author_rank: Super Contributor
timestamp: October 20, 2018, 10:27:00 pm
content: I would suggest a 4.7uF film capacitor with a rating of at least 25VAC.Something like this ought to work.https://www.digikey.com/product-detail/en/illinois-capacitor/475MMR100K/1572-1229-ND/5412701
REPAIR HP 48S - Page 1
Forum section: electronics / repair

author: Pluscrafter
author_rank: Regular Contributor
timestamp: October 17, 2018, 11:47:50 pm
content: I've found my HP 48, witch I've had learned programming 10 years ago, but today the calculator stucks, when I press the on BUTTON and the F Key. In won't react to any key press. Why is this happen? Could it be a rusty solder joint or something other and how can I open the calculator?

author: radioFlash
author_rank: Regular Contributor
timestamp: October 18, 2018, 03:03:53 am
content: You can try resetting it using a paper clip. There's a small hole you can access under one of the plastic feet:http://www.hpmuseum.org/cgi-sys/cgiwrap/hpmuseum/archv014.cgi?read=61858The calculator is held together with heat stakes, so disassembly is a pain and once reassembled, it may not fit together quite right again. You can search for "how to open hp48" to find some instructions and videos.

author: Pluscrafter
author_rank: Regular Contributor
timestamp: October 20, 2018, 06:25:50 pm
content: The reset doesn't help and the calc freezes after pressing the on key.Gesendet von meinem G8341 mit Tapatalk

author: helius
author_rank: Super Contributor
timestamp: October 20, 2018, 06:42:11 pm
content: My experience with these units is that they frequently have poor contact between the keypad and the board. You can try holding gently below the display bezel and see if that makes the keys work. If it does, the problem is inconsistent pressure on the "zebra strip" of the keypad.

author: SiliconWizard
author_rank: Super Contributor
timestamp: October 20, 2018, 06:43:25 pm
content: Here is a web page that describes the disassembly of the HP48 (to upgrade its RAM, but you'll see how to open the case).http://www.datacomm.ch/grundsch/page_upgrade.htmlSome pictures are missing but you should get the idea. Yes disassembling it requires drilling plastic rivets. Sucks. But if it's toast... you have nothing much to lose.Could be anything from a dry solder joint, broken wire, rust, or even a bad ROM...?Could also just be a stuck key.

author: Pluscrafter
author_rank: Regular Contributor
timestamp: October 20, 2018, 08:04:59 pm
content: The key works, but the calc(microcontroller?) freezes and you have to reset it.
Motor spec wanted - Kollmorgen GM05012005 12FG - Page 1
Forum section: electronics / repair

author: ThisNameIsBlank
author_rank: Contributor
timestamp: October 19, 2018, 12:21:18 pm
content: Hi,Thought this might be the best place to ask.I've got a kollmorgen GM05012005 type 12FG motor. But I have no idea what it is- type/voltage/power etcI tried asking kollmorgen but they weren't terribly helpful 'This is obsolete and was never sold in europe. refer to vendor' gee thanksGoogle failed to find anything useful so I thought id ask here.Assuming I cant find any useful info how would I go about working out what it is? it turns (fairly slowly) when I apply 12v dcthanks

author: awallin
author_rank: Frequent Contributor
timestamp: October 19, 2018, 04:58:27 pm
content: you might try the cnc-zone forum, they are into motors big time over there

author: ThisNameIsBlank
author_rank: Contributor
timestamp: October 20, 2018, 10:21:43 am
content: Cheers Mate, I'll try them.
bradley ct-471c multimeter - Page 1
Forum section: electronics / repair

author: m3vuv
author_rank: Super Contributor
timestamp: October 20, 2018, 10:23:52 pm
content: hi all ive one of these im repairing,just a quick question,on the amplifier board there is an axial capacitor 22pf at 750 volt,it seems sort of open circuit ,ie if i feed 100khz at 150mv in one side i get about 20mv out of the other side,the only thing i have is an air variable,can i use that in its place,in the circuit it looks like a coupling cap,regards m3vuv.

author: Gyro
author_rank: Super Contributor
timestamp: October 21, 2018, 09:44:49 am
content: Rather a dumb question as you don't indicate the input impedance of your measuring instrument or measurement setup. A 22pF capacitor has an impedance of about 72k at 100kHz.If you're measuring with a basic dmm with meter leads etc, then you'll get loads of un-quantified parasitic load capacitance that will swamp it, that's certainly going to make it seem 'sort of open circuit'.It presumably has a 750V rating for a reason.
Agilent E3646A Power Supply Repair - Page 1
Forum section: electronics / repair

author: TheDefpom
author_rank: Frequent Contributor
timestamp: October 19, 2018, 11:50:34 pm
content: Hi All,I thought I would post this here, the first part of the repair on a Agilent E3646A dual channel power supply.It had a fault with no output from channel 2, and then whilst diagnosing it I also lost the voltage feedback on the same channel, part one shows how I diagnose the faults, repair the voltage feedback fault, and even trick the unit into working, part 2 (once recorded) will show the repair of the actual output stage.I intend to do a live stream on my channel in 19 hours time, I will be trying to substitute U139 (a CS8122) with a MCP100 supervisor IC to restore channel 2 output, the CS8122 is obsolete so I am working out what can be successfully used in its place, there is another part which I am waiting to arrive which is supposed to be a drop in replacement but it is also obsolete, however they can be found on aliexpress, they are probably fake but if they work I don't care!Electrically these are very similar to other models, such as the E3647A, E3648A, E3649A, and also the E3632A, so the information I share in the video will help with repairs on those units also.
Need help replacing transformer - Page 1
Forum section: electronics / repair

author: elimenohpee
author_rank: Contributor
timestamp: October 06, 2018, 11:44:02 pm
content: I'm repairing a board that looks to have a broken power transformer but I'm having trouble finding a replacement. The primary and secondary has 4 pins on each side, but the coils are attached only to pins "1" and "4"; the inner pins "2" and "3" are unused and look to only be used as a mechanical support. When I look on Digikey, I can only find transformers that have secondary's with multiple circuits with the option to parallel or series the circuits together. The board doesn't route those pins so those transformers won't work in this situation. I'm sure these transformers are out there, I just don't do repairs like this very often and am not able to find them.As far as selecting the replacement, the primary is mains fed (115 VAC) and the secondary goes through a full bridge rectifier to a 5V regulator with a 2V dropout voltage. I measured the secondary current draw and it is less than 100 mA.Thanks for all the help

author: jaruco
author_rank: Newbie
timestamp: October 19, 2018, 07:39:51 pm
content: What you are looking for is called a split bobbin type of transformer. A quick search on the web revealed many hits. Since you already know the voltage and current requirements, finding a suitable replacement should be easy. Regulator circuits that use something like a 7805 require an input voltage that is at least 1.2V above the desired output voltage to function correctly. Be aware that any voltage that exceeds that will have to be dissipated as thermal energy by the regulator so a secondary voltage of 7-9V should be satisfactory. Take a look at the "images" when you search for this. Russ

author: tautech
author_rank: Super Contributor
timestamp: October 20, 2018, 06:33:38 am
content: Check the primary winding for a open thermal fuse......not uncommon.It should be under the tape at the end of the winding.Be sure to add a fuse if you're going to bridge or remove it.
Albrecht AE6490 - Page 1
Forum section: electronics / repair

author: Jane
author_rank: Frequent Contributor
timestamp: October 19, 2018, 10:28:13 am
content: The CB Albrecht AE6490 has a problem with transmitting. Front panel shows that Albrecht transmits yet, no output power on antenna connector.So I would guess power amplifier could be faulty. What voltage should I measure on output antenna connector?In the schematic, there are also few test points but not given a proper voltages.One is marked as TP1 Driver. I expect it should be an output voltage of a driver block. Is it an input voltage for amplifier block?What voltage is normal for that driver output?Thanks

author: CJay
author_rank: Super Contributor
timestamp: October 19, 2018, 11:17:43 am
content: Service manual is here:http://www.cbradio.nl/abrecht/Service_Manual_Albrecht_AE6490_ENG.pdfYou won't be able to measure a DC voltage on the output, you need a dummy load, power meter or diode detector.

author: Jane
author_rank: Frequent Contributor
timestamp: October 19, 2018, 02:14:11 pm
content: Thanks for the reply.Unfortunately the schematic does not give test point voltage values.>You won't be able to measure a DC voltage on the outputI know you are right but I do not understand the reason.Is a modulation reason?

author: CJay
author_rank: Super Contributor
timestamp: October 19, 2018, 03:04:24 pm
content: Quote from: Jane on October 19, 2018, 02:14:11 pmYou don't need testpoint voltages, the collector of the final should be somewhere around 8V to 13V with no modulation but you will find it difficult to measure if there's RF present.The reason you won't measure a DC voltage on the antenna socket because there should be no DC voltage on the antenna socket, there should only be RF which is high frequency AC, that's why you need the dummy load and a diode detector or RF power meter.Does the front panel show power when you transmit?

author: Jane
author_rank: Frequent Contributor
timestamp: October 19, 2018, 06:16:26 pm
content: Thank you for the reply.>the collector of the final should be somewhere around 8V to 13V with no modulation but you will find it difficult to measure if >there's RF present.How to check that the final transistor( collector) is working properly and a problem is behind it?Or how to check that there is RF present or not ?With a scope?Yes, the front panel shows power when I transmit.Do you have any idea how to continue with a repair?Thanks.

author: CJay
author_rank: Super Contributor
timestamp: October 19, 2018, 08:09:35 pm
content: What test gear do you have?

author: Jane
author_rank: Frequent Contributor
timestamp: October 19, 2018, 08:42:52 pm
content: I have a power meter, dummy load, scope 200Mhz, digital multimeter
DC Permanent Magnet Brush Motor - alignment between brushes and magnets - Page 1
Forum section: electronics / repair

author: EEBlackSheep
author_rank: Contributor
timestamp: October 17, 2018, 11:51:50 am
content: On a certain motorcycle, from 2012-2016 the start motors are notorious for working poorly. We have investigated numerous causes (batteries, grounding, cables, relays), but have found that swapping starters with known good starters usually fixes the issues. So I have disassembled a few starters to see if I can find the internal problem. One interesting thing I have found is that there are no alignment marks on the case so that the orientation of the brushes to the permanent magnets is not consistently aligned.I do not know enough about DC brushed PM motors to know if this is really an issue or not. Is it? Could this be our culprit?I have attached a couple of photos of either end of the motor.

author: amyk
author_rank: Super Contributor
timestamp: October 17, 2018, 12:03:41 pm
content: Yes, the alignment certainly matters because the commutation needs to happen in alignment with the position of the field:https://en.wikipedia.org/wiki/Brushed_DC_electric_motor#The_commutating_planeEarly large motors had an explicit adjustment for this. You will have to experiment to find the best position.

author: EEBlackSheep
author_rank: Contributor
timestamp: October 17, 2018, 04:31:43 pm
content: Great info - thanks very much.

author: james_s
author_rank: Super Contributor
timestamp: October 17, 2018, 05:26:41 pm
content: Back when RC cars used brushed motors, most of the better motors had adjustable brush timing. The effect is similar to adjusting the spark timing on a gasoline engine.

author: Kleinstein
author_rank: Super Contributor
timestamp: October 17, 2018, 07:46:08 pm
content: The adjustment has some effect on the motor. Though not DC anymore, but similar, in brushed motors used in electric drills some shift the brushes when changing the direction, as the best position depends on direction of rotation. Those with a fixed position get lower power from a given motor or need to run at reduced voltage in reverse.However there is no direct universally correct angle, as there can be an additional effective rotation where the windings are connected to the collector. So it is more a question of mechanical space the brushes are often just in the the center between the magnets.

author: james_s
author_rank: Super Contributor
timestamp: October 19, 2018, 12:47:27 am
content: Just like the camshaft or ignition timing in a gasoline engine, the timing is only ideal for one specific set of circumstances, for all others it's a compromise.
Help with identifying this OLED display - Page 1
Forum section: electronics / repair

author: spilihps
author_rank: Regular Contributor
timestamp: October 18, 2018, 07:21:10 pm
content: Hello!I rescued an OLED display from an nice Alpine headunit, CDA-9855R, and thought it would be fun to run with a microcontroller.So i was wondering what make and model it can be. The PCB marked with "Panel oeld" may not be a part of the display it self.Please see these images:https://ibb.co/fxZrO0https://ibb.co/kQVnwLhttps://ibb.co/erRGqfhttps://ibb.co/k2ucVfThanks for any help!

author: coromonadalix
author_rank: Super Contributor
timestamp: October 18, 2018, 08:26:00 pm
content: The chip driver is the rectangle blob on the flex pcb, to make it work you will need the radio schematics to find voltages and pinouts and maybe got it to work, you may loose lots of time doing so. And theses display are made for car radio usage not every day to day projects.Personnaly i would toss it, you have lots of small to big displays on the web with known pinouts and related projects ...

author: spilihps
author_rank: Regular Contributor
timestamp: October 18, 2018, 08:31:13 pm
content: Quote from: coromonadalix on October 18, 2018, 08:26:00 pmNot sure how this post is supposed to help me identify the datasheet for the display though.You see, there is a possibility that it’s a common oled display, used in many applications not just this particular radio..

author: glarsson
author_rank: Frequent Contributor
timestamp: October 18, 2018, 08:40:54 pm
content: Locate the schematics to the radio (as recommended in the post you said didn't help) and find the pinout. This is your only clue unless you can find some identifying number on the display. Perhaps someone recognizes it from the display.But, is it worth the trouble? Small OLED displays are cheap...

author: spilihps
author_rank: Regular Contributor
timestamp: October 18, 2018, 08:45:47 pm
content: Quote from: glarsson on October 18, 2018, 08:40:54 pmI wouldn’t say that a good quality white OLED in this size is cheap..

author: glarsson
author_rank: Frequent Contributor
timestamp: October 18, 2018, 09:05:05 pm
content: Quote from: spilihps on October 18, 2018, 08:45:47 pmThat's relative. Cost of known display with documentation (and perhaps working driver) versus many working hours reverse engineering the display and trying to locate more displays if a spare part is needed later.
Dell J727N / 2700W UPS Fan Replacement - Page 1
Forum section: electronics / repair

author: cogliostro
author_rank: Newbie
timestamp: October 14, 2018, 02:14:54 pm
content: Hi guys, i have some questions on replacing a Fan on an 2014 Dell UPS. The old San Coolers are 92mm Fans and are pretty noisy. So i looked the Case and find out that 120mm Fans would fit in it.So I have disassembled the Unit and try to replace the Fans by myself but everytime now the UPS starts to shutdown because of Fan Errors. Now i checked the old SanCooler 92 Model 9A0912S4004 cross with my new Noctua Coolers. And they have an huge difference in Amps. The old SanCooler 92 have 12V with 0.27A and draw on my Rigol PSU 0.200A or 200mA the new Noctuas with 12V draw about 0.90 A or 90mA. So i have done the math on it and the Ohm is at 0,06 at the SanCooler and 0,1333 on the Noiseblockers. You guys have any ideas on how to go on with the project ?Thats the Datasheet of the current Fanshttps://www.sanyodenki.com/archive/document/product/cooling/catalog_E_pdf/San_Ace_92A25_E.pdf-> SanCooler 92Datasheet of the 120mm Noiseblocker replacementshttps://www.blacknoise.com/datas/downloads/datasheets/TData_eloop120_122012_de.pdfManual / Datasheet of the Dell J727N / 2700W UPShttps://www.jecomponents.com/img/h950n.pdfThanks for your support.EDIT: I also getting a site wire failure on the UPS when i try to start the unit. What is pretty strange to me bcz. i read that means that the Unit is not connected to ground ? But i live in Germany and i'm almost 100% certian that the normal 230V here is always grounded ? Manual says here "Schuko to C19 16A Europe (Schuko)" and thats exactly what i have here

author: cogliostro
author_rank: Newbie
timestamp: October 17, 2018, 07:06:13 pm
content: also if you have an alternative Fan that works OOB would also be great ? No one ?
Transistor identification - Page 1
Forum section: electronics / repair

author: joao2004
author_rank: Contributor
timestamp: October 17, 2018, 09:03:55 am
content: Could someone help me identifying the transistor in the photo?

author: StillTrying
author_rank: Super Contributor
timestamp: October 17, 2018, 09:30:25 am
content: Googling BUH51 gives realistic looking results.

author: joao2004
author_rank: Contributor
timestamp: October 17, 2018, 09:50:31 am
content: Quote from: StillTrying on October 17, 2018, 09:30:25 amThank you, that's it. I was not associating the letters B and U

author: In Vacuo Veritas
author_rank: Frequent Contributor
timestamp: October 17, 2018, 03:22:54 pm
content: You have some nicely zapped resistors there as well!
Marconi 2024 TCXO Replacement - Page 1
Forum section: electronics / repair

author: jaruco
author_rank: Newbie
timestamp: October 17, 2018, 10:35:20 pm
content: The MI 2024 has a TCXO (HY-Q TCO-1009) that outputs less than 1MHZ. After removal it checks out at 10.0003MHZ. The voltages of +5V and +11V are ok. Is it really bad or have I missed something? I have replaced the power supply and the display but it only has a blue screen and no text. Any ideas would be most welcomed. Regards, Russ

author: CJay
author_rank: Super Contributor
timestamp: October 18, 2018, 05:10:26 am
content: Have you tried it back in the 2024?Have you checked the amplitude out of the TCXO?It's possible you might have 'fixed' the problem by removing it, it's also possible the problem will reappear at some point in the future.

author: jaruco
author_rank: Newbie
timestamp: October 18, 2018, 10:14:22 pm
content: Good call. I am reluctant to put it back in because removal is a pain. Based upon you suggestion, it seems that I should get a good replacement to put in and be done with trying to decide if it is good or not. The waveform on the scope is a slightly distorted sine wave on the advancing side.Russ
Agilent 33220A Display... - Page 1
Forum section: electronics / repair

author: saradr
author_rank: Newbie
timestamp: October 16, 2018, 10:45:54 pm
content: This Agilent 33220A was marked "Bad Display" (see jpg)... Took a go at cleaning the encoder before trying to locate Agilent P/N 0960-2545/ sub contractor cage code 09820 P/N REB161(9X5)PVB15FHINA1-2-24PCE and it came right up. If anyone else is looking at similar try cleaning first....

author: lowimpedance
author_rank: Super Contributor
timestamp: October 16, 2018, 11:09:34 pm
content: That is one confused display !.Thanks for the tip.
Fixing a charger - Page 1
Forum section: electronics / repair

author: anda
author_rank: Newbie
timestamp: October 10, 2018, 07:32:01 am
content: I am trying to fix a small battery charger. I have had the component out of the board and checked them.except for the optocoupler, the mc358m and and a 6 pin ic with no reading on it. Perhaps a power ic?The is power up to the transformer but no sound from it.I have orderet a optocoupler and a mc358m. Dont know how to check them. What can the 6 pin chip be?The board is a haider hbn3a2004 A B. Cant find it via google.

author: xavier60
author_rank: Super Contributor
timestamp: October 16, 2018, 08:22:24 pm
content: The 6 pin IC is possibly a SMPS controller by Richtek or some another brand. Does the IC drive a MOSFET?
Tecpel DMM8007 (8050?) meter issue - Page 1
Forum section: electronics / repair

author: Serracin
author_rank: Newbie
timestamp: October 16, 2018, 02:54:02 pm
content: This meter has a dead displayAnd idea from where I shall start please?

author: coromonadalix
author_rank: Super Contributor
timestamp: October 16, 2018, 09:54:45 pm
content: Check the main ic number, unless it is a black blobCheck your other thread for the schematic it may give you some hints, they are similar meters ... you need the backplane drive signal to make the lcd work.
Philips PM3540 problem in power supply - Page 1
Forum section: electronics / repair

author: mahimah
author_rank: Newbie
timestamp: October 16, 2018, 08:21:12 am
content: Hello,I have a Philips PM3540 oscilloscope and I have a problem with it. The intensity of the beam on the CRT increases very bad. So, I have to reduce the intensity by volume. but the beam light is very high and the measurement of frequency is shown wrong. I think the problem is from the high voltage transformer and I heard some noises from it. When I knap with the screw to the transformer the intensity changes to the normal state for a second.I download the user manual from the site. but it is only 37 page and does not have the service manual.So, anybody can help me?
Battery ID for a PMAT 2000 - Page 1
Forum section: electronics / repair

author: Jwalling
author_rank: Unknown
timestamp: October 11, 2018, 02:02:21 pm
content: Hoping someone recognizes this battery pack. I don't have the originals.Just short of 9" long or so... 2 battery packs in each unit. Located under the hard drive/floppy.All I know is that it's Li-Ion. the opening looks familiar, but scouring Ebay got me nowhere.

author: coromonadalix
author_rank: Super Contributor
timestamp: October 11, 2018, 10:06:21 pm
content: I would say try to contact Teledyne for batteries replacement, or try to have some numbers ?? googled this thing, never found any battery number nor description ??They ressemble some terminals std pins, maybe you could try to build some battery packbut i see some battery sense pin

author: Jwalling
author_rank: Unknown
timestamp: October 12, 2018, 09:26:32 am
content: Quote from: coromonadalix on October 11, 2018, 10:06:21 pmTeledyne may be the next place to try. I've requested a quote for this, but no response yet:https://www.locatory.com/aircraft-part/P2K615A06
R&S NGPV 40/3 service manual - Page 1
Forum section: electronics / repair

author: maginnovision
author_rank: Super Contributor
timestamp: October 15, 2018, 05:37:55 pm
content: I emailed R&S for a service manual and they replied with "No, we don't offer them for proprietary reasons". So I'm trying to see if someone has the manual/schematics for it because I know that is not strictly true.Added photos for immediate problem. Power resistor for low speed fan burned up so only turns on when pretty hot. Goes across this temp switch to drop the 250Vac. I have some resistors ordered but no idea what is right, or if any will fit well.
HP/Agilent 6812A A9 output board L500, L501, L502, L503 values - Page 1
Forum section: electronics / repair

author: piotekp90
author_rank: Contributor
timestamp: October 09, 2018, 09:31:22 am
content: Hi,Does anybody know the inductance of the L500, L501, L502, L503 inductors in the A9 output board in HP 6812A ac power supply?I have this power supply but I see that this inductors have cracked cores and I would like to replace it.

author: Chris56000
author_rank: Frequent Contributor
timestamp: October 09, 2018, 09:52:43 am
content: Hi!I wouldn't have thought they'd be much more than 40–100uH each about 3A rating – there's full component–level circuit diagrams in the service manual by the way!Post clear pictures of the chokes please – it might help us identify replacement core kits you can use to repair them!Chris WilliamsPS!Have you got one of those little cheap and cheerful Component Testers,?

author: piotekp90
author_rank: Contributor
timestamp: October 10, 2018, 11:54:23 am
content: At the beginning I have checked the service manual and schematic but there is no information about the choke value. If I put the part number on Keysight website I recive an information that this is obsolete part (without any more information about the choke).I measured the chokes and they have around 100uH.

author: piotekp90
author_rank: Contributor
timestamp: October 12, 2018, 07:54:53 am
content: I have received informatin from Keysignt about this inductors:)E CORE; 12.6 MM WIDE; 20.5 MM HIGH; 29.2 MM LONG; 1 SECT; FR MATL; 12 PINS; RECT. HOLE. BOBBIN-COIL FORM E CORE; 12.6 MM WIDE; 20.5 MM HIGH; 29.2 MM LENGTH; RECTANGLE HOLE SHAPE; 1 SECTION; APPLICATION : M 42/20; MATERIAL: REINFORCED NYLON 6/6 TO UL94VO; NO. OF PINS: 12 (2X6)Inductance: 93-101uH @5V ocv. 100kHz 1.2 to 5.6
Agilent 16803A boot error - Page 1
Forum section: electronics / repair

author: rtekal
author_rank: Contributor
timestamp: October 10, 2018, 08:41:46 am
content: HiI have a windows 7 based Agilent 16803A logic analyzer at work, which was not booting up. I removed the HDD and connected it to a PC and performed check disk, with no errors. I backed up the data to my PC before putting it back into the instrument, and decided to do an factory recovery in the following steps.1. Selected recovery option.2. Ran the checkdisk without errors.3. Ran the system drive repair.Rebooted the instrument after every step, to see if the problem was resolved, but the problem remained.4. Finally ran the recovery process. At 10%, a popup window came with the message that recovery was successful. After automatically rebooting, an error message was displayed that 'Winloader.exe' is corrupt or missing. Repeated the same recovery process multiple times and ended up with the same message. I did a slow motion video of the recovery process and on replaying saw that a error message was displayed for a split second, before it exited the recovery.I am attaching the snapshot of error messages.Suspecting the recovery partition to be corrupted, I got another working logic analyzer, into which I replaced the faulty HDD and ran the recovery which was successful. After restoring the recovered HDD to the primary instrument, checked it to be working fine. I monitored the instrument for a couple of days, recycling the power for any failures. The instrument worked fine.My question is why did the recovery process fail in the primary instrument.Regards

author: Tony_G
author_rank: Super Contributor
timestamp: October 10, 2018, 06:41:59 pm
content: Did you swap the drives in the working unit or just add the faulty drive as a second HD?TonyG

author: rtekal
author_rank: Contributor
timestamp: October 11, 2018, 09:44:23 am
content: I swapped the drive in the working unit. If not the original drive would be overwritten as the recovery software does not give an option for drive selection.Regards

author: Tony_G
author_rank: Super Contributor
timestamp: October 11, 2018, 07:09:23 pm
content: The recovery partition is on the drive that you swapped in so there wasn't anything wrong with it. Check that the bios settings match between the units.When I reinstalled my 16902B I had to reset them as the battery had died on the board.TonyG

author: rtekal
author_rank: Contributor
timestamp: October 12, 2018, 04:38:11 am
content: will check it out
TI-82 STATS does not power up properly anymore. - Page 1
Forum section: electronics / repair

author: Refrigerator
author_rank: Super Contributor
timestamp: October 06, 2018, 08:44:17 am
content: My precious TI-82 has been having problems powering up for about a year now, it would take a few tries to get it running and sometimes it would even display "MEM CLEARED", after one good power up it turns on without problems if i don't leave it off for too long.Also most of the time after a difficult power on it has the contrast way up so i have to re-adjust itBut now i pulled it out to do some TL431 resistor divider calculations and it doesn't power up anymoreHas anyone had this happen? Could it be a simple fix?BTW, the batteries are good.PS: while writing this post i gave it another try and it powered upand the contrast is way up as well.

author: shakalnokturn
author_rank: Super Contributor
timestamp: October 08, 2018, 11:34:31 pm
content: Quote from: Refrigerator on October 06, 2018, 08:44:17 amThis may sound a stupid question of course: You have checked the backup battery too?Otherwise check PCB for battery corrosion.

author: Refrigerator
author_rank: Super Contributor
timestamp: October 11, 2018, 03:26:05 pm
content: I had it replaced before the other one went bad but i figured it wouldn't hurt but the next day i had a "MEM CLEARED" and i knew it had nothing to do with the batteries.The one buttoncell that i replaced was still like new so i keep it in the battery tray as a spare.
Visonic Powermax Pro - Installer Mode not visible - Page 1
Forum section: electronics / repair

author: NiToNi
author_rank: Newbie
timestamp: October 11, 2018, 01:38:49 pm
content: I just picked up a second hand panel on eBay to replace the faulty one I already had.However, the Installer's menu ("Installer Mode"), which typically is visible as an option at the end of the User's menu ("User Setting"), is not there! After "Scheduler", it toggles back to "<OK> to exit".I have performed a hard reset using the EDF jumper a few times but to no avail.Any tip on how I could get into the installer menu because the panel's pretty useless otherwise...