hybridfree/eevblog-posts huggingface dataset:
Marshall CV500-M-2 "Lipstick" Camera Repair (Parts Identity?) - Page 1
Forum section: electronics / repair

author: clickykbd
author_rank: Newbie
timestamp: June 11, 2017, 07:43:49 pm
content: Hello again,I've got this older HDSDI lipstick camera that I let the magic smoke out of by using the wrong power supply a while back. I think I've spotted the blown parts...1 - Allegro Microsystems A4490 DC-DC Switching Regulator (20-WFQFN)https://www.digikey.com/product-detail/en/allegro-microsystems-llc/A4490EESTR-T/620-1245-1-ND/1831590Datasheet:http://www.allegromicro.com/en/Products/Regulators-And-Lighting/Multiple-Output-Regulators/A4490.aspx1 -Unknown part, silkscreen L10, two visible letters are possibly '?RJ', but there is a nearly identical looking part near by with '680' markings.... although now that i've taken the photos I'm leaning towards '7R7'?The photos:https://drive.google.com/open?id=0Byf6vxRkqU-fSGx5NVRTanlSd1Uhttps://drive.google.com/open?id=0Byf6vxRkqU-fMkROaHdMd3hxOVkhttps://drive.google.com/open?id=0Byf6vxRkqU-fQVNHclZrTnZoZzghttps://drive.google.com/open?id=0Byf6vxRkqU-faHpGTnVlU21jUFkAlso, being new to SMD repair, is this the type of thing that warrants reflow? Or possible doable with just hot-air rework? I've managed some small parts with hot-air (my station is only a week old), but never a attempted a 'chip' type package yet.Thanks for the help!Ryan

author: clickykbd
author_rank: Newbie
timestamp: July 04, 2017, 06:53:38 pm
content: A bit more information, and i'm leaning towards an inductor (ferrite bead maybe?, as an "L" number might indicate).The one on the left (non-damaged) measures 3.07ohm, the visibly damaged one measures 0.17ohm in it's current state. I would say they were the same but they obviously had different markings originally.These are near board connectors on the flip-side, so noise filtering?For testing to power up I would I be safe to just short that one?(provided i've replaced the A4490 first).Forgive the perhaps newbie assumptions.Thanks,Ryan
Part identification - Page 1
Forum section: electronics / repair

author: thefamilyman
author_rank: Regular Contributor
timestamp: July 03, 2017, 10:31:57 pm
content: Good morningCould someone help me identify a part for me?Its part of a standard repair kit for a Stamford alternator rectifier. These kits are expensive but consists of just 2 types of components; half a dozen diodes (3x SKN 26/08 UNF and 3x SKR 26/08 UNF)and another which i suspect is a varistor.If i can get these components individually it would save me a small fortune.

author: Armadillo
author_rank: Super Contributor
timestamp: July 03, 2017, 10:51:36 pm
content: I think its a phase control thyristor in Disc Housing.
Battery charger with a blown current sense resistor. (FIXED) - Page 1
Forum section: electronics / repair

author: Refrigerator
author_rank: Super Contributor
timestamp: July 01, 2017, 08:35:49 am
content: Found a blown current sense resistor in my battery charger but i can't decode the colors.Tried many online calculators but can't find one that would tell me what value brown-black-gold-grey-black is for.

author: bktemp
author_rank: Super Contributor
timestamp: July 01, 2017, 08:57:57 am
content: brown-black-gold -> 1 ohmgrey -> 10% toleranceAnd the last black one could be something non standard, like indicating a fusible resistor.

author: Armadillo
author_rank: Super Contributor
timestamp: July 01, 2017, 09:17:01 am
content: brown-black-gold-"burn ring"-black -> 1 ohm Precision 0% tolerance. [current sense! 0.1%, 0.01% etc]tolerance must be on the raised portion on the right side.

author: Refrigerator
author_rank: Super Contributor
timestamp: July 01, 2017, 09:22:06 am
content: I put a big fat 1R0 resistor and i'm getting 148mV across during charging, which translates to 148mA.The charger is rated at 1.5A charge leading me to believe that the resistor is 0R1

author: Refrigerator
author_rank: Super Contributor
timestamp: July 01, 2017, 09:50:07 am
content: Yes it was a 0R1, i didn't have a suitable resistor at that size so i series paralleled some smaller 0R1 resistors and also soldered some sheet metal to heatsink it.The battery now gets charged at 1.33A, which is close enough.
Eaton Evolution 850 UPS repair - Page 1
Forum section: electronics / repair

author: microbug
author_rank: Frequent Contributor
timestamp: July 01, 2017, 03:44:26 pm
content: Hi all,I've got a dead Eaton Evolution 850 UPS (board images), left over from an RMA (seller didn't want it back). I have new batteries for it and the device powers on, but a warning LED lights up and it quickly powers down again. The main board is connected to C13/14 inputs and outputs, a management interface board and a transformer of some sort (presumably an auto transformer since this is a line-interactive UPS). I can take pics of all these but they all look fine and there's not much to see.I opened the thing up and found a suspicious-looking power resistor (pictured). It's marked '10WS10KJ', I foundthis datasheetthat seems to include it (the dimensions also fit). By the marking it should be a 10k±5% resistor, and it measures 9.8k -- could something still be wrong with it?I've checked the two fuses near the battery inputs and they're fine. Various connectors aren't connected right now as I've had to remove them to get a good look at the board.Any ideas?~~ microbug

author: ovnr
author_rank: Frequent Contributor
timestamp: July 01, 2017, 03:54:43 pm
content: The resistor is fine, some idiot just put glue on it in the factory, which has become rather toasty.

author: microbug
author_rank: Frequent Contributor
timestamp: July 01, 2017, 03:55:37 pm
content: Oh well, anything else obviously wrong here?
HP 3325A function generator's High voltage option (option 002) - Page 1
Forum section: electronics / repair

author: lyonsk
author_rank: Contributor
timestamp: May 24, 2017, 02:13:40 pm
content: Hello guys,I got my hands on HP 3325A function generator with Option 001 (owenized oscilator) and Option 002 (High voltage output). It was sold as having power supply issues but is fully functional except of high voltage option. This option is simply 2x amplifier that amplyfies the output. It is separate board with own +/- 30V power supply. Disadvantage is that both owen and high voltage board is permanently turned on causing the caps to die very soon.Except for the dead caps, diode bridge and +15V stabilisator I found one dead transistor. It is Q6 which should be 2N3904 both according to what is marked on the part and the part list and should not be a problem to buy. Since the schematic schows that the amplifier is symetrical I asume that the complementary transistor Q7 must match the new transistor. I was not able to identify what standard type of transistor is Q7 based on the part number 1853-0020 but 2N3904 is typicaly matched with 2N3906. Is it possible that it is indeed 2N3906 but selected to tighter tolerances and therefore it has own part number?So what now?1.) Should I try to find a match for original Q7 or replace both?2.) How should I compare the properties of the two complmentary transistors? hFE? Vbe?

author: RobK_NL
author_rank: Frequent Contributor
timestamp: May 25, 2017, 11:48:28 am
content: There is nothing in the manual to indicate that these two transistors are / should be matched, so I wouldn't worry too much about it.

author: lyonsk
author_rank: Contributor
timestamp: June 30, 2017, 12:59:21 pm
content: Hello guys,I pulled some transistors out and measured their hFE using this circuit:http://www.geofex.com/Article_Folders/ffselect.htmYou can check attached schematic where orange numbers represents hFE.To me it looks like each side of the circuit should have the same overall hFE so basicaly hFE of Q6 should be equal as Q13...I replaced the transistor with the closest one I had (hFE = 228) and the circuit works. Output is within tolerance when checked for DC voltage using generator's offset function. I don't have spectrum analyser. Maybe the offset could be a little bit better. Now it is -35mV but as one is supposed to use this option with amplitude over 10Vp-p I say it is good enough.

author: Kleinstein
author_rank: Super Contributor
timestamp: June 30, 2017, 03:31:12 pm
content: hFE matching should not be critical in that circuit. It is more or less like a normal audio amplifier. The main part to set the offset is the input transistor pair (Q1). If at all it would be about Vbe matching in a way that U(Q6) - U(Q4) = U(Q7) - U(Q5). However the setting is not that critical. If really needed one could adjust the offset (many options). i won't expect good DC precision from this circuit anyway.Q6 and Q7 are just for setting auxiliary voltages and compensating some temperature drift. So they are not critical.
I2C bus corrosion   - Page 1
Forum section: electronics / repair

author: Flappy
author_rank: Contributor
timestamp: June 30, 2017, 09:43:31 am
content: Hello,I have been replacing a lot of SAA1064 ICs on boards that have been exposed to rainwater and I have noticed that the corrosion is almost completely isolated to the clock and data pins. Are conductors that carry AC with a DC offset more susceptible to electrolysis? Does frequency play a part? Is there such thing as corrosion resistant data protocol?

author: AndyC_772
author_rank: Super Contributor
timestamp: June 30, 2017, 09:53:02 am
content: Yes, they are. That's precisely why telephone networks are powered from -48V with respect to earth, rather than +48V. You could argue that the negative bias constitutes a "corrosion resistant" protocol at the hardware layer.Better to keep the water out in the first place, though.

author: Rerouter
author_rank: Super Contributor
timestamp: June 30, 2017, 10:30:38 am
content: For limited DC bias, your looking for Manchester encoding, it makes sure there is an even amount of data sent as a positive and a negative, and a clock is generally safeThe issue with I2C is that it idles high, which means it has a voltage gradient to the ground surrounding those pins, allowing for corrosion,In buried wiring they will run a sacrificial anode which sits at a positive voltage in relation to the wiring to be protected, so that it gets eaten away first. e.g your I2C bus in this case is playing the sacrificial wires to the ground plan.

author: jpanhalt
author_rank: Super Contributor
timestamp: June 30, 2017, 11:35:27 am
content: Just remember Michael Faraday's definition of "anode" as the electrode at which oxidation (corrosion) occurs. Ford used to use a positive ground until the mid-1950's. There is debate as to its effects:https://mechanics.stackexchange.com/questions/1934/what-are-the-tradeoffs-for-positive-vs-negative-groundJohn
Electrical ballast Repair - Page 1
Forum section: electronics / repair

author: Bskitter
author_rank: Regular Contributor
timestamp: June 28, 2017, 08:17:50 pm
content: Hello Guys, I am trying to repair a ballast circuit for a small floresent blub.I placed a bulb in which was the incorrect value and it damaged the ciruict it somehow.One day I get home and I could smell some magic smoke was escaping. I now found the correct type of bulb and the light is not constant but more like a warping effect.I have tested both transistors and the large capacitor, they are fine.Can one guide me to what could be wrong ?I do not have a schematic but here is a photo of the blub if that helps

author: Armadillo
author_rank: Super Contributor
timestamp: June 29, 2017, 03:36:00 am
content: Did you twist in the tube correctly.Only 8 diodes and 7 resistors. So just use a multimeter to measure and check those to be within normal range.

author: eKretz
author_rank: Frequent Contributor
timestamp: June 29, 2017, 05:26:27 am
content: I've repaired a fair number of similar ballasts - this is one of those compact fluorescents with the U-bulb isn't it? Usually on the ones I've repaired, these fail at a resistor or diode in the circuit path near the transistor.

author: Cyberdragon
author_rank: Super Contributor
timestamp: June 30, 2017, 01:15:35 am
content: One of those diodes is missing it's polarity (cathode) band! Check those two resistors next to the large green capacitor, I see smudges which might be burn marks.

author: Armadillo
author_rank: Super Contributor
timestamp: June 30, 2017, 02:36:19 am
content: Quote from: Cyberdragon on June 30, 2017, 01:15:35 amYou need to desolder it out from the circuit to confirm it again.For resistors, check resistance against resistor color band. If cannot get, desolder from the circuit and measure again.Ascertain before change policy.

author: bktemp
author_rank: Super Contributor
timestamp: June 30, 2017, 06:32:12 am
content: Quote from: Cyberdragon on June 30, 2017, 01:15:35 amIt could be the DIAC used for starting the oscillator. This type of diode will show as open in both directions when checked with the diode test function of a DMM.If all diodes are ok, it could also be the foil capacitors being damaged by the wrong load.
ZXY6005 buttons malfunction - Page 1
Forum section: electronics / repair

author: malekblbl
author_rank: Newbie
timestamp: July 01, 2017, 05:49:57 am
content: I have a ZXY6005 Buck Converter, it was working really well until suddenly buttons stopped working properly, in fact it seems like they swap functions.ZXY6005 have 5 buttons "UP / DOWN / <-> / SEL / OK" but now its all messed up.UP is still UPDOWN is performing UP<-> is performing DOWNSEL is performing <->OK is performing SELI don't know if it's a software or a hardware problem, as per the attached schematic it may be the 3.3v supply or a resitor connected to the buttons, just guessing.does anyone had this problem, you help is much appreciated.

author: rg58
author_rank: Regular Contributor
timestamp: July 01, 2017, 07:23:55 am
content: It's basically just a simple voltage divider. The controller meassures the voltage on PIN 11 and is translating this into a function.1) Check 3.3V near R41- TURN OFF -2) Check R41 = 1MOhm - pull-up resistor for PIN 11 = High (unlikely the cause, but check it anyway)3) Check R42 = 10kOhm4) Confirm resitance between R42 right side (3.3V) and R49 (left side=GND) is 10.4kOhm (or less)5) Double-confirm R43 right side to R49 left side (GND) is 400 OhmI assume either the 3.3V are too lowORR42 has gone higherORa problem with the soldering between the resistors of this voltage divider. Can you see that the key is performing the function that the previous key (further left in the schematic) was supposed to do? A sign of lower voltage which corresponds to the function of the other key (as evaluated by the controller on PIN11).
What Defects Can Affect An IC? - Page 1
Forum section: electronics / repair

author: FPTEC
author_rank: Newbie
timestamp: June 30, 2017, 03:55:06 am
content: Hello,What defects can affect an IC?I have had a bit of trouble making sure a BGA CI is defective.I know it depends on the IC, but roughly, which tests do you recommend?Thank you.

author: rs20
author_rank: Super Contributor
timestamp: June 30, 2017, 06:24:44 am
content: Looks at the IC's datasheet. Check that all of the facts stated in the datasheet are true of the IC in front of you.For example, if it's an op-amp, check that is amplifies. If it's a microcontroller, check that it communicates over JTAG and computes. You'll have to be much more specific about the IC you have before we can provide any remotely applicable advice, I suspect.
Help with HVAC/Refrigeration symbology - Page 1
Forum section: electronics / repair

author: staze
author_rank: Frequent Contributor
timestamp: June 28, 2017, 02:41:43 am
content: Hi All,I'm trying to repair a wine fridge, and I'm not positive about the symbology on these two mechanical thermostats. Attached are images.I think I figured out that the triangle in the circle is the compressor, and the thing in parallel with it (connected to pin 3 on both) is a blower (this unit doesn't have one), but what is the circle with the X in it? The main difference between the two appears to just be a circle with an X through it between Line and pin 4 on the 53007.Also, the "switch" piece, should it connect to pin 3 or pin 2 when the thermostat is on (temperature has not been reached) or off (basically, is that NC or NO)?Thank you!

author: Armadillo
author_rank: Super Contributor
timestamp: June 28, 2017, 04:12:26 am
content: Apparently the symbol does not conform to international standard like IEC, BS. I think its a mix between the company own HVAC and Electrical symbols. I suppose the X is a light indicator.

author: IanB
author_rank: Super Contributor
timestamp: June 28, 2017, 04:23:22 am
content: Quote from: staze on June 28, 2017, 02:41:43 amThe circle with an X through it is a lamp. For instance, see here:http://www.electronic-symbols.com/electric-electronic-symbols/electric-lighting-symbols.htmThe switch operates according to the picture next to it: when the temperature goes down enough it moves from pin 3 to pin 2, stopping the compressor.

author: orion242
author_rank: Unknown
timestamp: June 28, 2017, 09:50:54 am
content: Circle with triangle is typically a pump, symbol below that is a fan.
Repairing a CLIO "clearview" audio device - Page 1
Forum section: electronics / repair

author: k1mgy
author_rank: Regular Contributor
timestamp: June 27, 2017, 11:10:41 pm
content: A friend handed me his broken Clio. This is a nifty stereo speaker device that uses an curved acrylic panel, driven by what appear to be piezo-based transducers for left and right channels. It also has a ported subwoofer in its base.It was claimed that only one channel was operating. Indeed, testing revealed this to be so. Furthermore, at idle, the unit was drawing >500ma, which seemed strange.After disassembling I found two mylar capacitors at the broken channel (approx sizes 2512 and 1206), and both appeared to have leaked out their goodness. One of the nearby traces was eaten away. There are two others at the working channel, and these measured 10nf and 1.5nf in circuit. But not trusting an in circuit test I tried to desolder and remove these.. and of course managed to destroy both.No parts list or schematic can be found.I'm guessing the output circuit is specific to driving a piezo transducer... but never having done so with audio, it's difficult to know what values of capacitors might work here.

author: DaJMasta
author_rank: Super Contributor
timestamp: June 28, 2017, 01:45:35 am
content: If they're just AC coupling the signal path, then bigger means better low frequency response - sometimes these last coupling caps can be tens or hundreds of microfarad, but usually a few to ten is sufficient (depends on the impedance of the device they're driving, which varies with frequency).If you have an LCR meter, try measuring the speaker element at various frequencies to get an idea of the impedance, then you can plug that into a high pass filter calculator and get an idea, but if they're surface mount and actually are film caps (most surface mount caps I see are either ceramic or tantalum), they can't be huge values because film caps just don't go that high.Now this would only count for one of them in each side, the other is probably for filtering and would need to be the right value if it actually is a film cap, but if it's a ceramic or something, it could just be for decoupling and any old value would do.I would start by tracing out this portion of the circuit to see what it's functioning as, which should give you an idea of the ballpark values of the caps and how important it is to be right with the value. In a lot of instances, larger is fine and won't hurt.
Hantek DSO1062B problem offset? - Page 1
Forum section: electronics / repair

author: frenzel.92@wp.pl
author_rank: Newbie
timestamp: June 27, 2017, 02:51:36 pm
content: Help with oscilloscope DSO1062B.HelloThe problem with the device began with the writing of measurements to an usb drive with format (NTFS). It should be FAT32 which has damaged the software the device started up and restarted. I accidentally formatted the memory and had to re-set the system. With the help of a hantek.com redirector sent me a download instruction and a new soft by JTAG. The device starts up however...The device turns on, the ohmmeter multimeter etc are working properly.The problem is with the oscilloscope.symptoms:No zero line, in the DC and AC range, the line appears in the GND range.Only the upper part of the signal waveform can be seen, the displayed signal is shifted.The signal can only be seen in the range up to 5V. Above 5V does not display the waveform.For both cannons the same symptoms.Do not pass Self calibration.Could this be a software corruption?Hot to AD9288. After soldering resistors for LMH6552 (RA01, RA02) AD9288 does not heat up. And there is a no signal line on the screen.Voltage on systems tested.DAC OUT (DAC8551) -> VPP 0.800V is ok?With disconnected probes:OFFSET1 -> -1.2VOFFSET2 -> 2.5V (Tp502)OFFSET3 -> 1,6VIs it ok?Tp501 -> 4,096V is ok.For OP2-C TLV274C -> 2,5V.After replacing the resistor and setting offset1 to 2.5V there was a zero line.Please advice as if I could fix my oscilloscope.The attachment adds a file that I found on the network and on which I base the measurements.https://youtu.be/5JRmlAXg5VM
How to Identify Components and ICs with Foreign Codes ???? - Page 1
Forum section: electronics / repair

author: FPTEC
author_rank: Newbie
timestamp: July 01, 2017, 04:01:08 am
content: Hello,It is increasingly common to find components with strange codes that have no results on google.This makes identification difficult. What to do to identify in these cases?Thank you.

author: rg58
author_rank: Regular Contributor
timestamp: July 01, 2017, 07:06:20 am
content: Sometimes the first letters are omitted, so it is hard to find it if you don't know the full name. Can you post a picture? Maybe we can identify it. Apart from that, those could also be custom-made ICs.

author: FPTEC
author_rank: Newbie
timestamp: July 01, 2017, 07:46:07 am
content: It is not a specific case, the goal is to know methods that can be used in front of all this.Yes, I usually know many ASICs in my area of expertise ...Only the majority is not ...And they are often identified by sites of destruction, as I do not know, but are identified.
R&S CRTU -rohde & schwarz service circular #1684 - Page 1
Forum section: electronics / repair

author: g4wyz6
author_rank: Newbie
timestamp: June 27, 2017, 03:26:28 pm
content: When setting up the levels for Tx deviation, a dialog box opens stating that the deviation will be reset to 0.000kHz. If it needs to be extended read 'R&S service circular #1684'I've Googled this term in-various permutations, but nothing useful was found.73's Mike g4wyz

author: BreakingOhmsLaw
author_rank: Frequent Contributor
timestamp: June 27, 2017, 10:45:34 pm
content: Hello Mike,this probably referred to a service bulletin on the old (now defunct) R&S Service Board.A quick Google search suggest that might be its replacement?https://gloris.rohde-schwarz.comHave a go at that.Cheers, Marcel
ILX lighwave LDC-3742 repair - Page 1
Forum section: electronics / repair

author: h.bashar
author_rank: Contributor
timestamp: July 13, 2016, 09:57:23 am
content: Hello EEVblog community, my first post here! My name is Hasanain and I am a control engineer from Sheffield/UK, I recently acquired a non-functioning ILX-Lightwave LDC-3742 laser diode driver unit, the unit powers up with error code E-413, checking the operation manual the code has to do with serial eeprom checksum error presumably on the TEC unit.Unfortunately, a search on google failed to return a service manual for the unit and before I attempt removing the actual TEC module for inspection I was wondering if there are any laser aficionados here on the forum that may have scan of the service manual.Best wishesUpdate! I have examined the digital board and it does not contain any serial eeproms so I removed the TEC module and bingo! found the faulty (perhaps) 8 pin socketed chip by national semi 93C06EN, I am not sure if a replacement will render this unit functioning again, I suspect it holds some sort of calibration data or some look up tables for the temperature sensors. I will pick up one of these chips and give it ago and try to hack into the data on the faulty eerprom (6 x 16bit spi)and see what it contains. I have also attached some picture of the unit tear-down. If you guys have any input on this by all means leave a comment.cheers2nd Update!: I have dismantled the unit down to the power supply board, and measured all the voltages and they all appear to be correct, so it appears that the eeprom in question is indeed faulty!3rd Update: At last some real progress!, the problem is not the eeprom, its the optoisolater connecting the TEC module to the MCU board, confirmed by swapping around the socketed 6n136, the unit no longer display the error code. I have ordered several of those and will update soon.

author: joaomcferreira
author_rank: Newbie
timestamp: June 27, 2017, 06:27:55 pm
content: Hi HasanainI hope you have managed to repair your controller.I have just come across your post while searching a service manual for a similar equipment, LDC-3714B.I was calibrating the quipment, according to User Manual and I found a problem with the measurement of the laser voltage, it always reads zero, either in the display or using GPIB interface. I would like to repair it.Have you got any schematics, service manual or any usefull information that you can share with me?Looking forward to hear from you.Best regards, Joao
Wanted: LeCroy ASIC  MDS403 - Page 1
Forum section: electronics / repair

author: BreakingOhmsLaw
author_rank: Frequent Contributor
timestamp: June 27, 2017, 10:21:51 pm
content: Hi,anyone selling a LeCroy MDS403 ASIC or a spare video board for a 94xx series LeCroy ?I have a dead 9410 here without deflection. Turns out the DACs that control the line drivers do nothing, because they are not getting any data from the big ASIC.I can see data on the input lines of the MDS403, the output lines to the DAC just rest at 0,4V, so i guess it's a goner.PM me please if you are willing to sell parts.Cheers!

author: digsys
author_rank: Unknown
timestamp: June 27, 2017, 11:47:10 pm
content: Don't have what you need, but been in a similar boat many times - option2 is to find a dead unit, usually very cheap, then pay the seller to remove all the "good" parts anddump the rest. The probability of the exact same fault would be rare imo.
Lecroy Waverunner LT342 Repairs (encoders, LCD backlight, BNCs, ...) - Page 1
Forum section: electronics / repair

author: eb4eqa
author_rank: Regular Contributor
timestamp: June 25, 2017, 06:47:05 pm
content: Hi,Just finished repairing and documenting the many repairs I did on the LT344 oscilloscope.http://www.rbarrios.com/projects/lecroylt/Regards,Roberto EB4EQA

author: Armadillo
author_rank: Super Contributor
timestamp: June 25, 2017, 07:36:43 pm
content: Great site you have there.

author: marshallh
author_rank: Unknown
timestamp: June 25, 2017, 09:13:50 pm
content: Great work
Extracting coax inserts from ERNI/EURO backplane connectors - Page 1
Forum section: electronics / repair

author: TerraHertz
author_rank: Super Contributor
timestamp: June 25, 2017, 03:10:55 am
content: The 10.000000 MHz reference board I was given [https://www.eevblog.com/forum/testgear/list-your-test-equipment-score-here!/msg1240933/#msg1240933] uses EURO style backplane connectors, with coax inserts.To have one connector for playing with the reference card, it's necessary to extract the coax connectors from the backplane. Something that I gather requires a very specialized tool, that I don't have.Here's an improvisation that works.It needs something that can be pushed down into tiny slots to release the spring retaining clip. I tried a few kinds of sheets of stiff insulating plastic, as used as barriers between PCBs and metal chassis. The one that worked is 0.25mm thick, and quite stiff.Cut four little strips just under 2mm wide. While pushing the coax connector forwards (towards where the card would be, to free the sharp rear edge of the spring from the plastic connector body) use small flat-nosed pliers to shove the plastic strips into the four slots around the connector. Push hard, rock and and rotate the coax back and forth to help the strips work down and compress the spring.Once they won't go any further, use a small screwdriver to lever the coax connector out to the rear. It still takes quite a bit of force, but does not break the connector. Rotating the connector some more helps.This was the first time I was able to successfully remove these things from connector bodies. Eight out of eight worked. So I'm quite pleased.

author: SeanB
author_rank: Super Contributor
timestamp: June 25, 2017, 07:22:35 am
content: You get either a disposable insert/extract tool with the connectors, or you can get the proper thin stainless steel tube tool for them, that does the same job of releasing those springs. Same style of tooling will get the pins in those connectors out as well.
CMU200 - CMU-B21 Universal Signalling Unit -A dumb question - Page 1
Forum section: electronics / repair

author: g4wyz6
author_rank: Newbie
timestamp: April 04, 2017, 09:01:52 pm
content: I have a no frequency modulation on the transmitter, using the CMU200 maintenance tools. I've narrowed the fault to the MC68K module, the error message in the states that a block of data is unknown (ID, 0), see photo 1.In the function description of the board states that an RS232 interface is available for debugging, the CMU-B41 issue 2, has a USB connector!Also what software do I use for debugging.Help would be very appreciated please.73's Mike

author: oh2ftu
author_rank: Regular Contributor
timestamp: April 05, 2017, 05:41:15 am
content: Try to run the firmware upgrade corrections from the bootup menu.There are people on the forum that are more experienced with debugging these, but I would sense there is a correction table missing or similar.You could also try to reseat all modules

author: g4wyz6
author_rank: Newbie
timestamp: April 06, 2017, 08:13:08 am
content: Thank you for your suggestions, I've run those and still having the same issues.Opps I've notices I made a typo error in the Subject line, its a CMU-B21, the -B41 is the Audio Generator.

author: RF_fanatic
author_rank: Regular Contributor
timestamp: June 24, 2017, 10:00:29 pm
content: Try FM calibration after at least 30 minutes powered up.You can remove the complete B21+attached module and reroute the cables and see if that solves the issue.For amateur use the B21 signalling unit and attached add on hardware options for GSM are useless so better remove it so it can also not damage other modules like the powersupply.The only interesting option you have is the Bluetooth, so that is also gone if you remove the above but at least it is worth a try bypassing them to check. (really lift the unit out of the motherboard and remove the orange power cable at the bottom)
hameg hm1507-3 osiloscope - Page 1
Forum section: electronics / repair

author: icomdealer.ir@gmail.com
author_rank: Newbie
timestamp: June 06, 2017, 06:01:52 pm
content: Hello.i have a hameg 1507-3 (150 mhz ) osiloscope , there is some thing wrong with it . it some times works fine but mostly after turning on the oscope , it begins to spark and scintillation ( you can hear the sound in the short clip) . what is the problem ? can anyone helpyou can see the problem in this clip :https://youtu.be/sGwUKPu3Xhoregards

author: icomdealer.ir@gmail.com
author_rank: Newbie
timestamp: June 07, 2017, 08:10:27 pm
content: no idea ?

author: grumpydoc
author_rank: Super Contributor
timestamp: June 07, 2017, 08:20:16 pm
content: The EHT is arcing somewhere, open it up and look for obvious signs of carbonisation, loose EHT connector etc.Turning it on in a darkened room with the covers off may enable you to see where the problem is.However, be careful - the anode voltage in a 'scope is anything up to 20kV, don't probe, prod or touch if you are unsure what you are doing, and remember that high voltages might be presenteven with the power turned off.

author: icomdealer.ir@gmail.com
author_rank: Newbie
timestamp: June 23, 2017, 08:02:19 pm
content: Hello . i opened its cover in a dark room . the spraks are from a component that is similar to voltage multipier package in stungun (i attach the picture) it may be eht unit as you said .the sparks seem to be inside the component and on its surface .also at the buttom of smps board there was a effect of spark , at the place of connection between that component wire and the board.should i replace that component or it will be repaired ?may the problem be some where else and cause that component to spark ?please helpregards

author: grumpydoc
author_rank: Super Contributor
timestamp: June 23, 2017, 09:20:12 pm
content: Yes, that is the EHT multiplier.It will need replacing by the sound of it - the difficulty is normally getting hold of the right part.

author: icomdealer.ir@gmail.com
author_rank: Newbie
timestamp: June 23, 2017, 09:36:13 pm
content: Tnx for your answer . How can i get a new one to replace ?

author: tronde
author_rank: Frequent Contributor
timestamp: June 24, 2017, 01:27:39 am
content: Quote from: icomdealer.ir@gmail.com on June 23, 2017, 09:36:13 pmI understand that SKY Messtechnik in Germany is service partner for older Hameg equipment. They stock spare parts and understand English.http://www.sky-messtechnik.de/kontakt-sky-messtechnik

author: icomdealer.ir@gmail.com
author_rank: Newbie
timestamp: June 24, 2017, 04:01:58 am
content: ok. tnx for your help . i will contact them.
BIOS Question - Page 1
Forum section: electronics / repair

author: Bskitter
author_rank: Regular Contributor
timestamp: June 14, 2017, 05:27:10 pm
content: Hello Everybody.A few months ago my friends laptop screen suddenly would not turn on.He took it to a "Repair" store and they looked at it and said it would cost him roughly 150 US dollars to fix.He then said he would think about it and took the laptop home with him. He then showed it to me and we looked at the motherboard to see what they worked on/tested.We saw that the BIOS chip and a lot of flux around it and it was obvious that they removed it.The repair store somehow put the BIOS chip into a test state and it told the GPU to iterate through RGB colors (To test if the chip and screen were still working).My question is where there is documentation about laptops and PC's bios programming and different states one could program the chip to work in.Byron

author: Nusa
author_rank: Super Contributor
timestamp: June 14, 2017, 06:24:19 pm
content: I suspect you're much more likely to get useful feedback if you include some important details, like the brand and model of the laptop, and how old it is.

author: Lolucoca
author_rank: Contributor
timestamp: June 23, 2017, 09:57:18 pm
content: If it's a MacBook, go look at Apple's website for an extended warranty period, their GPUs fail regularly and repair shops usually replace the BIOS chip even though that's not what's wrong with the machine... Early 2008 MacBooks for example. The GPU got too hot and died on a regular basis. I would certainly probe around and see if there are any voltage rails missing or something...

author: Rasz
author_rank: Super Contributor
timestamp: June 23, 2017, 10:23:23 pm
content: its most likely dell, booting with D pressed gives you lcd test patternsprobably something old with bad Nvidia G86, and that $150 was for cooki^^^oh im sorry, reflow repair ...
3456A parts - Page 1
Forum section: electronics / repair

author: mikeg
author_rank: Newbie
timestamp: June 14, 2017, 04:42:11 pm
content: Probably been asked....I did a bad thing. I broke one of the input jacks on my 3456A. Any sources for parts other than epay?I think I can glue it back together but I'd like a new one.A hanger queen from epay may be in the works for parts.

author: pelule
author_rank: Frequent Contributor
timestamp: June 14, 2017, 06:14:04 pm
content: As far as I know it is a complete 5 jack block.It may possible to replace the front input jacks with the rear input jacks (as I did it for my 3455A)./PeLuLe

author: Ordinaryman1971
author_rank: Frequent Contributor
timestamp: June 22, 2017, 05:14:19 pm
content: I think you can buy this style of jack on ebay. They are used also for the power supplies. Search High current binding post and you will find them. They are about $3 for a pair.http://www.ebay.com/itm/10Pcs-M5-Type-High-Current-4mm-Female-Banana-Jack-Socket-Test-Binding-Post-/182174413016?hash=item2a6a70f0d8:g:a7sAAOSwGIRXZAeI

author: DavidG
author_rank: Newbie
timestamp: June 22, 2017, 07:11:21 pm
content: pelule is correct that it's a 5 jack block. I believe pelule is also correct that the front and rear jack blocks are the same. I also think the 3455A and 3456A use the same connector; but I'm not as sure about that.I believe there should be more of these around than there are of the other parts necessary to build working units. So in theory you should be able to find an exact replacement if you can find someone willing to part with the front or back connector from a parts unit.

author: MarkL
author_rank: Unknown
timestamp: June 23, 2017, 07:16:41 pm
content: A quick peek at the 3456A parts list shows that both the front and back jack assembly is part #5060-7478. That covers all 5 binding posts.The 3455A has different part numbers in its parts list, but the on-line parts listing at Keysight shows that 5060-7478 is also used in the 3455A. So who knows.For single binding posts, some eevblog users have reported that BS-244MN-R (search for it) is a good replacement for HP/Agilent gear. Depending on what's broken, you might be able to use it to rebuild your broken assembly.I like the idea of swapping the front and back assemblies. Fix the broken jack as best as possible and hide the ugliness in the back.
MJE700 Wanted in Sydney - Page 1
Forum section: electronics / repair

author: myval
author_rank: Contributor
timestamp: June 23, 2017, 08:47:52 am
content: Hi,I am after one (or two) MJE700 transistors I need to fix a device and its is unfortunately friday evening and as usual it needs to be fixed preferably today.Would anyone of you have it or know where I can get it on Saturday in Sydney area?23-june is today to sync our clocksThank youJosef
53131A option -003 prescaler chip ID? - Page 1
Forum section: electronics / repair

author: Jwalling
author_rank: Unknown
timestamp: June 21, 2017, 04:02:23 pm
content: Rather than source a knock-off -003 prescaler board for my 53131A, I've decided to repair it if possible.The counter becomes unstable @3GHz when a signal less than about -15dBm is measured. I've replaced all 4 amps with no change in the symptoms. The output of this prescaler is / 128. I can see that it's output is jittery, and I think (hope) it's the defective part, however, I can't ID the markings on the chip.Anyone?

author: branadic
author_rank: Super Contributor
timestamp: June 21, 2017, 04:29:48 pm
content: Could it be an MB510 2.7GHz TWO MODULUS PRESCALER made by Fujitsu?

author: Jwalling
author_rank: Unknown
timestamp: June 21, 2017, 04:32:40 pm
content: Quote from: branadic on June 21, 2017, 04:29:48 pmThat could be it! that led me tohttps://groups.yahoo.com/neo/groups/hp_agilent_equipment/conversations/messages/73334Many thanks!
SMD Regulator part number - Page 1
Forum section: electronics / repair

author: McBryce
author_rank: Super Contributor
timestamp: June 20, 2017, 12:47:43 pm
content: Hi,I've been given a PCB to repair that has been subjected to physical damage. One of the parts I need to replace, which I suspect is a voltage regulator has the marking SQ3GE. It's a SOT23-5 device, but endless interweb searching doesn't turn anything up. Does anyone happen to know what this part is?McBryce.

author: bktemp
author_rank: Super Contributor
timestamp: June 20, 2017, 03:21:05 pm
content: Do you know the output voltage?R1122N341B has SQxx marking code.http://www.e-devices.ricoh.co.jp/en/products/product_power/mark/ME-R1122N.pdfThere is also NCP346SN1 with marking code SQZxx.

author: McBryce
author_rank: Super Contributor
timestamp: June 21, 2017, 06:59:57 am
content: Unfortunately not. I think it was probably 3.3V, but the main (only) IC has it's number filed off, so it's not that easy to say.McBryce.
Identify IC SUAH - Page 1
Forum section: electronics / repair

author: Kaio Macedo
author_rank: Contributor
timestamp: June 18, 2017, 03:26:25 am
content: Hello guys.I need to identify an IC with the SUAH description.

author: welpester
author_rank: Contributor
timestamp: June 18, 2017, 07:16:57 am
content: How many pins?-welpester

author: welpester
author_rank: Contributor
timestamp: June 18, 2017, 07:24:01 am
content: Would this help?https://www.sos.sk/pdf/SMD_Catalog.pdf-welpester

author: welpester
author_rank: Contributor
timestamp: June 18, 2017, 07:25:55 am
content: Quote from: blueskull on June 18, 2017, 07:22:56 amMaybe custom chip?-welpester

author: amyk
author_rank: Super Contributor
timestamp: June 18, 2017, 02:38:28 pm
content: Could it be this or similar?http://www.vishay.com/doc?62834

author: Kaio Macedo
author_rank: Contributor
timestamp: June 18, 2017, 08:18:07 pm
content: Quote from: amyk on June 18, 2017, 02:38:28 pmUnlikely. This type of mosfet is very rare on this PCB.In addition to SUAH, there is another description, this time generic, GND.

author: welpester
author_rank: Contributor
timestamp: June 18, 2017, 09:59:33 pm
content: Quote from: Kaio Macedo on June 18, 2017, 08:18:07 pmOh, i was quite sure that it says GNL or GNEMaybe it is grounding chip!Is that solder on chips top left corner?-welpester

author: Kaio Macedo
author_rank: Contributor
timestamp: June 18, 2017, 10:40:03 pm
content: I thought I made reference to the GND pin that many of these ICs have.

author: welpester
author_rank: Contributor
timestamp: June 18, 2017, 11:01:06 pm
content: Can you tell what that board is?-welpester
Bluetooth HC-05 module failures - Page 1
Forum section: electronics / repair

author: Wimberleytech
author_rank: Super Contributor
timestamp: June 18, 2017, 07:17:35 pm
content: I have purchased four HC-05s on Ebay. A pair worked fine initially but then one failed (no LED heartbeat). I substituted one of the others I had purchased. Worked for a bit (off and on over a period of days), then failed.These are connected to Arduino nano pro 5V boards. I have properly handled the 3.3V RX input coming from nano 5V TX output, so that is not the culprit.I checked the 3.3V regulator on the dead boards, and they are functioning properly.Anyone else experience high failure rate with these ubiquitous HC-05 modules?
(Project Repair/Mod) Valve Driven LED Nightlight - Page 1
Forum section: electronics / repair

author: Cyberdragon
author_rank: Super Contributor
timestamp: June 17, 2017, 07:38:14 pm
content: I had to sleep in the living room due to the heat and went to turn down the dimming control since it was way to bright to sleep and it started flickering like mad. So I open it up...Not only is the adjustment pot one of those closed in ones, but the solder on one of the joints was missing (either it was a cold joint and all fell off or I'm a dingus and forgot to solder it and it somehow still worked for months). I'm also going experiment with adding more resistance to the adjustment pot to increase brightness (have to be careful not to pop the LEDs though, I have no current limit resistor, could add one if it needs it though).I should also make a schematic for you guys so you can build one (will be on project thread). It's a good project for tubes you have lying around. Main project thread:https://www.eevblog.com/forum/projects/all-tube-automatic-led-lampnight-light/msg1008013/#msg1008013
Help indentify part (TVS diode?) - Page 1
Forum section: electronics / repair

author: Zmogas
author_rank: Newbie
timestamp: June 17, 2017, 12:34:16 pm
content: Hello,I stumble upon on this part on PCB.By using multimeter ("diode" mode) I found that this part acts like diode: center lead is anode, ends of part are cathode. Anode is connected to GND and cathode is connected to input of IC which receives signal from detector on cable. So my guess this is an TVS diode. I'm right? Nominal voltage of it I can guess, but how about allowed power and case style? Is it obsolete?

author: bktemp
author_rank: Super Contributor
timestamp: June 17, 2017, 12:43:26 pm
content: It looks like an EMI suppression filter:http://www.murata.com/en-us/products/emc/emifil/chipYou are probably measuring the ESD protection diodes at the input of the IC.

author: DaJMasta
author_rank: Super Contributor
timestamp: June 17, 2017, 03:39:02 pm
content: +1 to an RF filter, I've seen quite a few on the board I just finished fixing, though their form factor looks to be about 2x as long. They show up on the schematic looking like this, a small integrated filter:

author: Zmogas
author_rank: Newbie
timestamp: June 17, 2017, 06:01:27 pm
content: I desoldered that part and checked: indeed it is a filter.Thank you for info.
MTP2850 Multimeter (Mastech MS8226 pcb) - Page 1
Forum section: electronics / repair

author: Metermeister
author_rank: Contributor
timestamp: June 17, 2017, 12:59:50 am
content: Hello AllI'm in the process of repairing an old MTP 2850 DMM, I've replaced 5 caps and 1 resistor. Repaired the display and a few other quirks...a PCB schematic would make things alot easier so my question is...anyone have any idea where I could find such a schematic for this board? The PCB states it's an MS8226 clone. Alternatively if someone can point me to a good source for meter schematics in general that would also suffice.
Broke several 7/32" black plastic PCB locking blots on Tektronix 2430A - Page 1
Forum section: electronics / repair

author: lordvader88
author_rank: Frequent Contributor
timestamp: June 16, 2017, 09:08:02 pm
content: Back on Dec.31 I think , I took apart my scope because channel's vertical gain as displayed on the CRT, is not working right somewhere along the way.And I had used pillars to get out some 7/32" black plastic PCB locking blots and broke several. Sad thing is I even had the right size socket. With real life side effects u won't guess.Anyone know where to get some PM cheap me please, thanks. I'm in Canada, and they are plastic and weigh nothing, so it can't be more than the price of a letter and so could be from anywhere