hybridfree/eevblog-posts huggingface dataset:
Chinese switch mode power supply - Page 1
Forum section: electronics / repair

author: Lango1818
author_rank: Contributor
timestamp: November 12, 2024, 10:19:57 am
content: Just purchased two 240/48 volt 10 amp switch mode power supplies off Ebay I will repot further on the extremely bad workmanship soon. However I was wondering what authority one could send a complaint to about the unsafe nature of these supplies. One supply had a resistance of 8 ohms between earth and the main metal body and 200 ohms between the metal lid and earth. On investigation I found the circuit board to be a nightmare, with hr solder joints everywhere. Some components not even properly soldered in, I could move the output choke and capacitors making the wires slide in and out of the circuit board.I have repaired both power supplies and now have less than 0.1 ohms between earth and the metal case. They also appear to work as they should.

author: wraper
author_rank: Unknown
timestamp: November 12, 2024, 10:28:54 am
content: These often also have an e-waste mains side bulk electrolytic capacitor with a new shrink wrap to make it look less obvious it's salvaged trash.

author: fzabkar
author_rank: Super Contributor
timestamp: November 12, 2024, 10:54:18 am
content: Quote from: Lango1818 on November 12, 2024, 10:19:57 amIn Chinese manufacturing, the customer is the final phase of the quality control process.

author: Lango1818
author_rank: Contributor
timestamp: November 12, 2024, 05:25:02 pm
content: I guess so long as Blackrock/Vanguard are making a profit they do not care about quality control

author: Poroit
author_rank: Frequent Contributor
timestamp: November 13, 2024, 04:18:47 am
content: G'day Lango1818,Did you see this?https://community.ebay.com.au/t5/Buying/Electrical-electric-electronic-compliance-safety-and-regulation/td-p/2123944

author: Zero999
author_rank: Super Contributor
timestamp: November 13, 2024, 08:17:34 am
content: Why did you repair it? It isn't your job. Report and return it. The seller shouldn't be allowed to get away with selling junk.

author: Lango1818
author_rank: Contributor
timestamp: November 13, 2024, 03:18:35 pm
content: No I agree they should not be allowed to get away with selling junk. The seller has given me a full refund including post. No doubt they will continue to sell these items on E-bay. I repaired it so I could get a feel for the extent of the poor quality. I have also found the power semiconductors (NPN 2sc3022 and high speed diode) are all second hand recovered from junked equipment. Somebody else said the capacitors are often old and just have a new sleve on them to make the look new. At this point with up to 15% of the items I have bought from China being over rated, badly built and or plain fake nothing would surprise me.
Chinesium CUT50 Plasma Cutter doesn't cut... - Page 1
Forum section: electronics / repair

author: GarySlaghammer
author_rank: Newbie
timestamp: May 23, 2020, 04:46:14 pm
content: I got this in bits as a last chance saloon before the tip. Blown MOSFETs meant a new upper board had been bought previously. It's not quite the same so I've had to make some changes for it to work (a 24V switching circuit for the mains thermistor bypass relay for one).I have a continuous arc across the spark gap inside the machine when I hold the trigger now. The air solenoid actuates and air blows through at the recommended pressure of 0.4MPa/50-60PSI. I can get a constant arc to the work piece, but the spark gap inside the machine is also running (I believe it's supposed to be off once the arc is established at the torch, though the physics of this escape me as the circuit diagram I have for a similar model shows the spark gap across the transformer primary so I can't see why it wouldn't always be on). There is some minor arc-pitting of the work piece, but no plasma jet or cutting action (first picture). Numerous consumables have been tried.What else can I check?If I turn off the air supply, as it runs down I can get a quiet flame between the workpiece and the torch without the spark gap inside running (second picture). Moving the torch too far away from the workpiece causes the connection to be lost and the spark gap starts arcing again.I'm sort of au-fait with the operation of these machines (SMPS into flyback) but haven't the logic, training or experience to follow what could be causing this.
Identified - Chip ID: Intersil (Renesas) 022F FTWP - Page 1
Forum section: electronics / repair

author: kelemvor
author_rank: Regular Contributor
timestamp: November 01, 2024, 02:08:21 pm
content: Please help me identify this chip. It's 3mm² 16 pin. Appears to be marked infineon 022F FTWP on the package. The chip is on the logic board from an HP Enterprise Aruba Wireless Access Point APINH303.Seems like it should have been simple to find, but I've been coming up with nothing all morning. Any suggestions greatly appreciated.

author: fzabkar
author_rank: Super Contributor
timestamp: November 01, 2024, 05:49:15 pm
content: ISL28022, Renesas, bidirectional high-side and low-side digital current sense and voltage monitor with serial interface, 3V - 5.5Vcc, 0V - 60Vin, marking 022F, 16 LD QFN:https://www.renesas.com/en/document/dst/isl28022-datasheethttps://www.aliexpress.com/item/1005003917648997.html(photo)The logo appears to belong to Intersil which was acquired by Renesas.http://markingcodes.com/search/c/022fhttps://ipv4.google.com/search?q=filetype%3Adoc+OR+filetype%3Apdf+%22absolute+maximum%22+022f

author: kelemvor
author_rank: Regular Contributor
timestamp: November 01, 2024, 07:47:45 pm
content: Thank you so much! I guess I was off in left field, thinking the i was Infineon.
Chip ID - Kogan Smart Plug does not power up - Page 1
Forum section: electronics / repair

author: EvilDeece
author_rank: Contributor
timestamp: December 04, 2021, 10:27:51 pm
content: Hi folks,Can anyone identify the chip with the divot taken out of it in the top left of the board (U1)? My guess is it's a switchmode controller. Looking at a working board, the chip markings are 'ASZBWA', but Google isn't being helpful at identifying it.
Chip ID request: dp / 525 / BOF2306 - Page 1
Forum section: electronics / repair

author: BreakingOhmsLaw
author_rank: Frequent Contributor
timestamp: May 30, 2024, 03:27:29 pm
content: Can anyone identify the manufacturer? I'm not familiar with this logo. ("dp"?)It's an SMPS controller. 1,27mm SOP-7

author: fzabkar
author_rank: Super Contributor
timestamp: May 30, 2024, 06:15:19 pm
content: DPx525Some clues here ...https://v4.cecdn.yun300.cn/100001_2101295378/DP951X_REV1.0%20CN.pdfhttps://v4.cecdn.yun300.cn/100001_2101295378%2FDP970X_REV1.0_2020-03-01_CN.pdfhttps://ae01.alicdn.com/kf/S2dd342db82d842008e56b97baf24ed71c/DP9511AH-SOP-7-DP9511-Non-isolated-buck-LED-constant-current-driver-chip-is-brand-new.jpghttps://ae01.alicdn.com/kf/Scf055ad5948349eab2be1cccbf1525a6m/10-sztuk-partia-kaiweidzic-nowy-DP8628C-SOP8-DP8302-DP8628B-DP024C-DP9126I-BP3166A-DP9512-DP9128-DP3773-DP9511B.jpghttps://en.publicxin.com/product/32/

author: fzabkar
author_rank: Super Contributor
timestamp: May 30, 2024, 06:34:35 pm
content: This is the chip manufacturer:http://www.depuw.com/en/productlist_50_68.htmlMy browser sees nothing. :-(I tried several iterations of DPx525 in the search box, but I got nothing. Maybe the part number is DPxx525

author: BreakingOhmsLaw
author_rank: Frequent Contributor
timestamp: May 30, 2024, 06:54:22 pm
content: Thanks mate.Shenzhen Developer Microelectronics Co LTd.Never heard of them. Est. 2006.

author: fzabkar
author_rank: Super Contributor
timestamp: May 30, 2024, 07:05:12 pm
content: What about this?DP2525https://www.isweek.cn/Uploads/20150807/55c4275178729.pdfhttps://pl.aliexpress.com/item/1005001446757488.htmlBut this makes me suspicious ...https://pl.aliexpress.com/i/1005003913659497.html

author: Haenk
author_rank: Super Contributor
timestamp: May 31, 2024, 07:38:06 am
content: Just ask them dp@depuw.comChinese homepage works, but I can't find anything close to that part# - seems to be quite outdated as well...

author: coromonadalix
author_rank: Super Contributor
timestamp: May 31, 2024, 02:11:28 pm
content: could be this onehttps://pdf1.alldatasheet.com/datasheet-pdf/view/1756522/DEPUW/DP2525F.html
Chip ID - Page 1
Forum section: electronics / repair

author: OpenCircuit
author_rank: Regular Contributor
timestamp: January 30, 2020, 01:52:03 am
content: Shot in the dark here, but my $20 "Microscope" is in the mail - 1000x even. Anyone know what the part number is for this ( see yellow arrow below) or possibly a trick to help make the characters more readable? Only have a head strap magnifier (El cheapo) and still cannot see the letters/numbers to ID this thing.Might be a CM6800 control board according to this post (reply 6):https://www.eevblog.com/forum/repair/corsair-cx600-atx-smps-made-by-cwt-problems-not-working-need-similar-schematic/Board is from an ATX power supply on the primary side.Hoping it has something to do with the primary side not boosting.

author: OpenCircuit
author_rank: Regular Contributor
timestamp: January 30, 2020, 06:16:23 am
content: I believe it is OB5269CP

author: DaJMasta
author_rank: Super Contributor
timestamp: January 30, 2020, 06:39:49 am
content: A trick to read the letters is to just angle it differently - there are some angles where the etched plastic will be nearly invisible and some angles where it should be pretty clear, provided that it's there.

author: wraper
author_rank: Unknown
timestamp: January 30, 2020, 07:11:23 am
content: Quote from: DaJMasta on January 30, 2020, 06:39:49 amAnd clean with alcohol first. Laser marking is poorly visible when surface is covered with flux residues.

author: OpenCircuit
author_rank: Regular Contributor
timestamp: January 30, 2020, 06:21:30 pm
content: Thanks for the suggestions....that is precisely what happened - alcohol cleaning and angle.I am guessing/hoping internal heat/short made it so hard to read - I need to fix this thing for some odd reason. Something not quite right about the top surface of this chip. I will post a shot with my "microscope" when it arrives in a few days.

author: OpenCircuit
author_rank: Regular Contributor
timestamp: February 01, 2020, 08:55:07 pm
content: Does the chip appear to have damage?OK, I am not laughing any more...$18 "Microscope"! Worth every penny!
[CLOSED] Chip identification - Page 1
Forum section: electronics / repair

author: Andrew74
author_rank: Newbie
timestamp: June 27, 2020, 06:32:29 pm
content: Hi,I have a burnt up chip on a power command v and I am unable to determine the brand or part number of the IC. I have attached the images of the IC in hopes a grey beard can identify the manufacture. I can make out some of the part number; that beingUAUB. The images are quite large, hopefully that helpsUpdate: The back of the chip had another part number: NTAF 1432. Image below.Update 2: I think I have found the chip on Digikey by sheer luck...I'm ordering it now and hoping it will work. I will update this thread with the results just in case someone stumbles across this thread one day.https://datasheets.maximintegrated.com/en/ds/MAX9924-MAX9927.pdfRegards,Andrew
Chip identification on Fenix HP25R charge board. - Page 1
Forum section: electronics / repair

author: ghorizo
author_rank: Contributor
timestamp: September 21, 2020, 06:05:52 pm
content: Hi I'm trying to repair the board of a broken fenix hp25r. The large chip looks bust but I cannot find anything info searching MPGB 2611 444, Can anyone help me identify it please?

author: fzabkar
author_rank: Super Contributor
timestamp: September 21, 2020, 06:46:31 pm
content: MP2611, Monolithic Power, 2A, 1-Cell Li-Ion Battery Switching Charger For USB and Adapter Power, marking 2611, QFN14:https://www.monolithicpower.cn/cn/documentview/productdocument/index/version/2/document_type/Datasheet/lang/en/sku/MP2611/document_id/1402

author: ghorizo
author_rank: Contributor
timestamp: September 21, 2020, 09:21:32 pm
content: Quote from: fzabkar on September 21, 2020, 06:46:31 pmThank you so much! Sadly that big back panel I believe it means I won't be able to so much without a heat gun.
chip identification - Page 1
Forum section: electronics / repair

author: Greg J
author_rank: Regular Contributor
timestamp: July 31, 2024, 05:51:51 pm
content: EEV Blog hive-mind, what chip do you think is this?It's on robotic mower board, I suspect compass/accelerometer, but not sure. None of the other chips would fit that description.10 pin, super small package, looks to me like "653 CRG" , or "653 CR6". But I can't find anything matching this description.

author: suntime
author_rank: Contributor
timestamp: July 31, 2024, 06:45:00 pm
content: Hi,I think it's NXP Semicon MMA8653FCR1https://www.lcsc.com/product-detail/Accelerometers_NXP-Semicon-MMA8653FCR1_C132231.htmlRegards.

author: Greg J
author_rank: Regular Contributor
timestamp: July 31, 2024, 08:45:09 pm
content: that checks out, you're super quick! thank you!

author: fzabkar
author_rank: Super Contributor
timestamp: July 31, 2024, 09:45:37 pm
content: I sometimes find image searches to be useful.https://www.google.com/search?q=653+accelerometer&tbs=isz%3Am%2Citp%3Aphoto&udm=2https://www.aliexpress.com/w/wholesale-653-accelerometer.html

author: Greg J
author_rank: Regular Contributor
timestamp: August 01, 2024, 08:23:06 am
content: interesting.I think what thew me off was the second line, CRG/CR6 - which seems to not matter.They should get better resolution lasers and actually etch full name
Chip identification? Flyback controller that uses BJT? - Page 1
Forum section: electronics / repair

author: mikedoubleu
author_rank: Newbie
timestamp: January 11, 2020, 05:33:28 pm
content: Hello all,I'm wondering if anyone can help me identify a little 6 pin chip. It's the controller chip for a small flyback SMPS. I'm fairly new to these things, but it seems notable that the switching transistor is a BJT (SD13003) as opposed to a MOSFET. I'm hoping that can help me track down the part number, but I'm having a hard time so far.The marking is 20F09, and also 57A on another line.Also, there's no feedback from the secondary here, not sure if that helps identify a category to search in...Thanks for any help or advice!

author: T3sl4co1l
author_rank: Super Contributor
timestamp: January 11, 2020, 06:14:32 pm
content: TI makes one,https://www.ti.com/lit/ds/symlink/ucc28722.pdfbut I'd bet you have a Chinese version.Tim

author: mikedoubleu
author_rank: Newbie
timestamp: January 11, 2020, 06:36:23 pm
content: Ah shoot, close but no cigar. Pinout a bit different.Thanks for that though, I'll keep digging.

author: mikedoubleu
author_rank: Newbie
timestamp: January 11, 2020, 06:52:29 pm
content: SOLVED! It is OB2520.
Chip removal alloy - Page 1
Forum section: electronics / repair

author: jeffjmr
author_rank: Regular Contributor
timestamp: January 28, 2022, 05:07:59 pm
content: I am a big fan of the chip removal alloy marketed by at least two different vendors. It definitely makes SMD and even through hole component removal a breeze with minimum temperature.But unless there is some rare earth metal involved, I wince with sticker shock every time I have to replenish my stock.Does anyone know the secret formula of this solder and if a more conventional and affordable alternative exists?Thanks,Jeff

author: ESTechnical
author_rank: Contributor
timestamp: January 28, 2022, 05:23:24 pm
content: We've been buying it in bar form from herehttps://www.ebay.co.uk/itm/193702641106It sometimes isn't available but I grab some when it is, because the price is so much better. The composition is usually tin, lead, bismuth and indium.

author: mazurov
author_rank: Frequent Contributor
timestamp: January 28, 2022, 05:25:15 pm
content: It's an alloy consisting primarily of bismuth, lead, and tin. If you want to make your own, start with Rose's metal article in Wikipedia. Buying pure bismuth could be costly but you can use SnBi solder and add lead to it.Don't try to make Wood's metal.
choosing test point and making voltage measurement - Page 1
Forum section: electronics / repair

author: tl01magic
author_rank: Newbie
timestamp: April 19, 2023, 12:22:11 am
content: imaged below is excerpt from marantz sr9200 avrwhat is +5vl and +5vd ?and to measure each, do I just use the ground pin that is in between?

author: WattsThat
author_rank: Frequent Contributor
timestamp: April 19, 2023, 05:12:52 am
content: They are two different 5 volt points. Elsewhere in the schematic will have matching +5vl and +5vd arrows. Your partial schematic shows a connection to +5vl in the upper right corner, it connects to CC16, RC43 and the emitter of QC05.The power supply schematic section (the source of the voltages) will show if they are from the same regulator or perhaps two different regulators. GND is a common reference point. It is shown with the earth symbol so it is probably connected to the metal chassis of the unit. If that is the case (you need to investigate), you can just clip your multimeter black lead to the metal chassis. You can confirm that the GND point is the metal chassis using the resistance function of your meter.

author: tl01magic
author_rank: Newbie
timestamp: April 23, 2023, 10:05:34 am
content: Thanks so much!That was informative for me.judging by the size of heatsinks used for the regulators and burn discoloration around them, im thinking the issue will be there.Thank you for the tip to follow those traces back to their source.just in case is an easy answer / commonly known thing; are voltage regulators tough to substitute? I know things like power output transistors can be, but hoping voltage regulators are easier to source replacements for obsolete ones.though maybe all for naught, just noticed amp section has a mains hum to it :'( and if I understand right those can be nearly impossible to find cause / too many things / components could cause it. Maybe am wrong but think a good start is checking caps that are on grnd.

author: WattsThat
author_rank: Frequent Contributor
timestamp: April 23, 2023, 03:39:24 pm
content: The typical three terminal regulators are easy to source, the job is even easier if the part markings are industry standard stuff rather than custom manufacturers numbers.Measure the frequency of the hum, anything that is a multiple of your supply frequency is a sign of failing power supply filter capacitors. A scope is easiest way to troubleshoot as it provides both frequency and amplitude. A DMM would be the next choice if a scope is not available.
Christmas bulb repair - Page 1
Forum section: electronics / repair

author: sdancer75
author_rank: Frequent Contributor
timestamp: April 04, 2020, 08:30:00 pm
content: I want to replace some bulbs from a Christmas lights. The input voltage is 220v and there are 25 bulbs in each of total four rows. Making the calcs, each bulb is at least 220/25 =8.8 volts for it's brightest point.I tested one good bulb with a 12v battery but the light it wasn't so bright as I expected. Why?Regards,Ps: Despite the fact these Chinese lights are advertised as led they are not.

author: james_s
author_rank: Super Contributor
timestamp: April 04, 2020, 08:34:58 pm
content: What kind of 12V battery? Is it possible that the voltage is sagging? Are you sure it's actually arranged in series groups of 25 lamps?

author: sdancer75
author_rank: Frequent Contributor
timestamp: April 04, 2020, 08:53:09 pm
content: Quote from: james_s on April 04, 2020, 08:34:58 pmI attached a battery photo.Yes, there are four lines (parallel) with 25 bulbs each in series, total of 100.

author: james_s
author_rank: Super Contributor
timestamp: April 04, 2020, 09:49:47 pm
content: That's a very small battery for 12V, those internally are usually a stack of little button cells and can deliver very little current, try measuring the voltage of the battery with the bulb connected.My first guess would be they are 12V bulbs run a bit under to extend their life. 240V / 25 bulbs is 9.6V. What's that green box? Are you sure that doesn't drop the voltage too?

author: sdancer75
author_rank: Frequent Contributor
timestamp: April 04, 2020, 10:58:35 pm
content: The green box is the power supply, with a blinking program for each line. Line 1-4 are the bulb lines (25 bulbs each) and line 0 is the phase. The left most two wires are the wall socket.I will check the voltage drop tomorrow and I will let you know.

author: gorge441
author_rank: Contributor
timestamp: April 05, 2020, 06:01:39 am
content: I guess the reason for the lower brightness is voltage dropping. Please check carefully...

author: sdancer75
author_rank: Frequent Contributor
timestamp: April 05, 2020, 10:08:47 am
content: Yes, you have right, the battery voltage drop is about 6v, that's why...I got bored to use my bench power supply which is closed in my store closet.Thanks to all.
chroma 6314/63103 calibration - Page 1
Forum section: electronics / repair

author: f14
author_rank: Regular Contributor
timestamp: May 06, 2021, 05:31:59 pm
content: Hi Guys,I just repair 63103 load module, now it work well, but voltage read back seem out of specsSo I think it need calibration , Have any one know how to calibration this device?Thanks for you help!
Chroma 6345 electronic load mystery part identification - Page 1
Forum section: electronics / repair

author: KrudyZ
author_rank: Frequent Contributor
timestamp: September 10, 2019, 04:28:33 am
content: The part in question is in an SOT23-3 package with ABG printed on it.The reference designator starts with a Q, so it's unlikely to be an IC.Its function should be that of a current mirror, like a BCV62 with its emitters connected together and brought out on a single pin.From what I can gather without a schematics, it is used to mirror a current proportionate to the high side sense resistor voltage drop to the low side.Does anyone know what it might be?

author: MagicSmoker
author_rank: Super Contributor
timestamp: September 10, 2019, 08:14:52 am
content: Probably a PNP BJT. See the (mercifully short) list here:https://alltransistors.com/smd-search.php?search=abg

author: KrudyZ
author_rank: Frequent Contributor
timestamp: September 10, 2019, 07:08:23 pm
content: The 2SA1312 would fit package size and marking.Here is the schematics I backed out. It looks like a normal PNP actually works in this place and it doesn't require a current mirror as I originally thought.V1 and V2 are floating 5V supplies.The OPAMP is an Elantec EL2075.V3 is the voltage of the external UUT, e.g. a 20V power supply.V4 is the sense voltage seen across the high side sense resistors. There are also low side sense resistors elsewhere, but they are only used for the MOSFET drivers to control the current they pass individually.R1 is referenced to the low side of the UUT where the power MOSFETs are doing their work loading it.Their are five of these circuits in parallel, each sensing across a separate set of sense resistors that go to different pins of the load connector, but they are all shorted together on the load card.With no voltage on V4, R1 gets about 128uA. This gets reduced by 27.5uA/mV on V4, so it's running out of head room at about 5mV sense voltage. The actual sense voltage is twice that since it comes in via a 50 Ohm source terminated cable.This electronic load was meant to be used for load testing VRMs for motherboards and came with customized load cards (which I don't have). It is able to drain 300A, with a slew rate of 150A/us, so it requires very low inductance connections to the UUT.
Chroma 6404 issue - Page 1
Forum section: electronics / repair

author: Deni
author_rank: Regular Contributor
timestamp: March 30, 2019, 08:31:56 pm
content: I have Chroma 6404 programmable AC source whose output slowly (over several seconds period) changes output voltage for ca. 1-2V.I have service manual, but there's no schematics - only component layout. I would be VERY grateful if somebody has schematics and iswilling to share it...

author: coromonadalix
author_rank: Super Contributor
timestamp: March 31, 2019, 12:24:04 pm
content: Did you ask Chroma directly ?? maybe they would share it or provide it to you under a non disclosure agreement ?

author: PTR_1275
author_rank: Frequent Contributor
timestamp: March 31, 2019, 12:34:26 pm
content: I’ve asked chroma for documentation before. Got the usual runaround of “we can’t provide it to non authorized service centers”, then got a email from the Australian service center with some absurd cost just for me to send it back and look at it.If they’ve changed and you can get a service manual, I might try again

author: harrimansat
author_rank: Regular Contributor
timestamp: January 02, 2020, 10:16:20 pm
content: I need it too, mine has short protection, but when I disconnect the current transformer it works.
Chromecast 1st gen not booting - Page 1
Forum section: electronics / repair

author: MirtSergiu
author_rank: Newbie
timestamp: December 04, 2020, 10:14:30 pm
content: I have the 1st gen chromecast and couple days ago it stopped working. When i open the tv, it show the google logo for 5 seconds then it is showing black. I am using the original powerbrick and i also tried other chargers. Any ideeas?
CHY24C LCR Meter Nulling - Page 1
Forum section: electronics / repair

author: mustafayilmaz
author_rank: Contributor
timestamp: November 18, 2023, 03:30:55 pm
content: Hi everyone.I have a CHY 24c LCR meter that I bought used. However, in 200pF capacity mode, the screen does not appear as zero. It shows a value of approximately 5pF. When I turn the adjustment pot, I can reach this lowest value. The measurements are correct, for example a 1pF capacitor appears as 6pF. (5+1) How can I solve this problem? Does anyone have documentation for the device?Thanks.

author: RoGeorge
author_rank: Super Contributor
timestamp: November 18, 2023, 05:58:07 pm
content: Maybe the cables have too much parasitic capacitance.Can the instrument be adjusted to zero with all the cables unplugged?

author: mustafayilmaz
author_rank: Contributor
timestamp: November 18, 2023, 08:28:07 pm
content: Quote from: RoGeorge on November 18, 2023, 05:58:07 pmNo, unfortunately it does not zero when not connected to the cable.Since it is a used product, I think it is a partially damaged part.
circuit board help  - Page 1
Forum section: electronics / repair

author: bugsb
author_rank: Newbie
timestamp: June 10, 2024, 02:45:49 pm
content: just joined the forum for some advice and poss help .i have a hybrid inverter that i stupidly when i disconnected the battery leads reconnected them in a rush in reverse , now the main board is ok and working but no one on the solar forum has any idea what the tiny board is that started to burn out me guessing is a chargerits connected via +/- on the battery side and the same on the solar input side , i have tried the maker but no response, so guys any idea what it is , worth fixing or some sort of replacement see pictures

author: bugsb
author_rank: Newbie
timestamp: June 10, 2024, 02:47:04 pm
content: one more picture

author: Poroit
author_rank: Frequent Contributor
timestamp: June 11, 2024, 02:50:48 am
content: The image is not that clear.I suggest you remove the PCB and clean up the damaged area to see if the tracks are badly damaged.

author: bugsb
author_rank: Newbie
timestamp: June 11, 2024, 09:29:03 am
content: the tracks are damaged

author: squadchannel
author_rank: Frequent Contributor
timestamp: June 11, 2024, 12:05:42 pm
content: I know it is burnt to look at.If you are asking for help to repair it, you need at least a magnified picture of the damaged area, not enough information.
Circuit board, SOT23 component fault? - Page 1
Forum section: electronics / repair

author: sailor83
author_rank: Contributor
timestamp: April 13, 2020, 12:08:20 pm
content: I'm trying to figure out some errors on a Jungheinrich forklift machine. (ETV-Q20)On one circuit board there are a few SOT23 components, are they always transistors? Everyone exept one give me diode readings. So I'm thinking this one might be faulty. (the others are marked 6B something, I've tried google to find out what type it could be, but no success..)Are the SOT23 package always transistors or could they be something else?

author: Manul
author_rank: Super Contributor
timestamp: April 13, 2020, 12:26:17 pm
content: SOT23 can be a lot of things. BJT transistor, mosfet, diode, dual diodes, zener diode, etc. Even IC's.6B may be a BC817, but that is not guaranteed.

author: JKKDev
author_rank: Regular Contributor
timestamp: April 14, 2020, 09:02:04 am
content: Maybe post a picture of the board as it might be possible to figure out the function of the SOT23 from it's surrounding passives etc.

author: sailor83
author_rank: Contributor
timestamp: April 21, 2020, 08:11:24 pm
content: It's the one with circle around..

author: thm_w
author_rank: Super Contributor
timestamp: April 21, 2020, 10:41:47 pm
content: Can you trace where the two connections go?If it is BC817, then emitter is grounded which seems right. Top left pin would be base, right side pin collector.https://www.sphere.bc.ca/download/smd-codebook.pdf

author: sailor83
author_rank: Contributor
timestamp: April 22, 2020, 07:05:57 pm
content: Thanks! That pdf is something I've been trying to find
Circuit Diagram for Digimess DP3005 power supply - Page 1
Forum section: electronics / repair

author: BruceAnderson
author_rank: Newbie
timestamp: November 25, 2022, 11:17:17 am
content: Hi I have recently purchased one of these power supplies from ebay was sold as spares or repair.The problem is somebody has tried to fix it before and judging by the appalling smd rework and silk screen print had great fun removing parts and swapping them eg two diodes have been switched for capacitors on the opamp circuits which ain't right.Having a lot of trouble finding a circuit diagram to give me better odds on fixing this without having to reverse engineer the whole power supply.Any help would be much appreciated.

author: m k
author_rank: Super Contributor
timestamp: December 03, 2022, 09:27:16 pm
content: It seems to be pretty standard issue, both ways.Drop the actual name and start looking closer devices that are externally equal.One Farnell page had order numbers as HUC44-0x, maybe that can be used as a clue.
circuit diagram for repair on AGILENT / HP ESG series wanted  - Page 1
Forum section: electronics / repair

author: Jörg
author_rank: Regular Contributor
timestamp: April 03, 2021, 04:32:37 pm
content: Hello.Can someone help me with the agilent ESG series motherboard schematic? Specifically, I have the ESG E3344B.During troubleshooting, my measuring tip of the U504 has slipped. Since then the 32V supply voltage has failed. I replaced the LT1170.Unfortunately without success. I also can`t determine the + 12V raw voltage for generating the 32V on the U504.The + 12V on the TP505 is correct.The reverse engineering for this PCB is a bit complicated for me. A detailed circuit diagram can be more helpful to me.Best regards. Jörg
Circuit Specialists CSI 860 hot air rework - Air full on when switched off? - Page 1
Forum section: electronics / repair

author: appsman
author_rank: Contributor
timestamp: May 30, 2023, 06:06:48 pm
content: I got a used Circuit Specialists CSI 860 hot air rework unit. It seems to work OK, except when the power switch is turned off, the air goes on full tilt. Is this normal? I assume no because it then would have to be unplugged when not in use. I'm guessing that maybe, when turned off, the air is supposed to run for a bit to cool off the heater, and that maybe a timer is dead. This was a fairly popular cheapo hot air unit, so I'm hoping someone has one and can tell me how it's supposed to behave, if not what to fix. Photo of the unit is attached.

author: ataradov
author_rank: Super Contributor
timestamp: May 30, 2023, 06:56:46 pm
content: It should auto power off after the heater cooled down to some reasonable temperature, usually around 100 C.You can't simply interrupt the airflow across the heated element, it would burn out.

author: appsman
author_rank: Contributor
timestamp: May 30, 2023, 08:04:31 pm
content: Yes, that's what I suspected. The problem is that mine never turns off the air.

author: ataradov
author_rank: Super Contributor
timestamp: May 30, 2023, 08:39:37 pm
content: I would assume something is broken, I doubt it is supposed to work like that. But I don't have this specific one and never used it. But literally all others I used did the cooldown and shut down automatically.

author: floobydust
author_rank: Super Contributor
timestamp: May 30, 2023, 09:04:42 pm
content: It's strange the on/off switch is not as it seems. It looks 3 position.The wand on other brands has a magnet and there is typically a reed switch in the base- so the station knows when it's in the holster and to do a cool-down sequence.This might not be happening, although it should eventually shut the fan off when temperature is below a safe value.I'd take it apart...
Cisco 6506E Supervisor Engine with bad RAM - Page 1
Forum section: electronics / repair

author: tc0fh
author_rank: Newbie
timestamp: July 13, 2020, 05:56:04 pm
content: Hello from Romania!I have two Cisco 6506E switches with VS-S720-10G-3C supervisor engines that crash during boot. From the crash output, it looks like I'm hitting the problem described here:https://www.cisco.com/c/en/us/support/docs/field-notices/637/fn63743.htmlCisco says that some network equipment they sold has bad memory chips form a single manufacturer between 2005 and 2010. On the board in question there are two different memory chips: MT 46V16M16-6T (date code 0950) and Samsung K7N163631B-PC16 (date code 913).From Cisco's 2019 anual reporthttps://www.cisco.com/c/dam/en_us/about/annual-report/cisco-annual-report-2019.pdfQuoteMy question for the eevblog readers is this: have you encountered similar issues with those RAM chips? I would like to know which one is the culprit in this case in order to avoid replacing the good ones. Who is thesingle supplierin question?Thanks for your help!

author: nuclearcat
author_rank: Unknown
timestamp: July 13, 2020, 08:10:08 pm
content: Probably issue is in proper power down sequence and device designers missed this moment or it was published too late in errata.Something like this: (page 50 of MT42L128M32D1, LPDDR2)"An uncontrolled power-off sequence can occur a maximum of 400 times over the life of the device."As i understand, if power-off sequence is not done properly, latch-up(s?) happens and it burns slowly sensitive parts of chips.

author: asis
author_rank: Frequent Contributor
timestamp: July 13, 2020, 09:26:07 pm
content: Hi,I saw something similar with my own eyes in 2011. While inside the switching center, there was a power surge, UPS switched to batteries several times, but part of the network equipment still rebooted ...Failure: WLC2106 Cisco Wi-Fi controller and switch Cisco C2960-48TC-L.I read this bill:https://www.cisco.com/c/en/us/support/docs/field-notices/637/fn63770.htmlWLC2106 managed to exchange for a new one.Switch Cisco C2960-48TC-L was not restored.Moreover, in the course of life, other switch's began to come from other objects(C2960G-24TCL, 2811..3500 ..).About the RAM.All the same, we are probably talking about NOR Flash-RAM , because the initialization by including by power ON.There are no replicas on RS232 (ROMMON).Make a clone using the programmer by reading the desoldered FRAM from the working device - it does not work out because MAC address (S / N) is protected, there is a protection bit and there are areas of checksums.In addition, at the POST stage, the MPU mask is checked, which is read from the OTP MPU area.In my opinion, it’s not really possible to do anything.Vladimir.

author: tc0fh
author_rank: Newbie
timestamp: July 14, 2020, 11:36:55 am
content: Hello!Digging around point to the Micron as the bad memory.On the PCB there are 46V16M16-6T (TSOP66, Tck=6ns, CL=2.5) but I can't find the exact part. I can only find 46V16M16P-5B (TSOP66 LEAD FREE, Tck=5ns, CL=3).Can i use the -5B instead of -6T?Thanks a lot!
Cisco 7910 Cisco 7940 7960 dead no power fix - Page 1
Forum section: electronics / repair

author: dvd4me
author_rank: Regular Contributor
timestamp: September 26, 2022, 03:22:40 am
content: Hello,This is to address the power issue on these Cisco 7910 7940 7960 IP phones, they are getting killed by glitches in the Cisco Catalyst switches.Power overloading causes the short of a transistor and the phone dies, also it's becoming a short on the POE end.This is not boot loop issues or related flash corruption. Just power.All the details here:Cheers
Cisco C3560G-48PS POE Switch boot problem, but seems like HW issue - Page 1
Forum section: electronics / repair

author: premium
author_rank: Newbie
timestamp: August 14, 2021, 12:36:40 pm
content: Hi,i got a Cisco C3560G-48PS switch, with HW problems, but i have no idea, how to continue..It does not boot, no boot log on the console port. All of the LED indicators on the front are on, and are green. (not the port LEDs.. just the status LEDs) The fan works, but on the maximum speed. LAN ports are down.The 50V, and 12V is OK from the internal power supply. All low voltages are OK. (3.3V, 2.5V, 1.8V...) I measured all of the main board capacitor voltages, and checked for spikes, or noise, but all OK.Next, i resoldered the RAM chips. (according some youtube videos, it is a common problem.) No success.. After that, i replaced the two RAM chips. Nothing. Does not boot.on the connector of the mains PS, there are 4 cables, what i can't identify. orange, yellow, violet and pink. I can meassure 2.7V on the yellow cable, but nothing on the another cables. Is it normal? It look's like, this pins are comming from the external PS connector (if someone uses an external common power supply, not the fitted 230V one.. It has a different connector on the back side of the switch.) i think. Is it normal, that no voltage are present on this cables? What is the 2,7V??I have no other switch like this, so i can't compare it with an other. But i have a C3750-24PS. With the same fault. (does not boot, all indicators are on, except the port LEDs..) It has got a different power supply, but with the same connector. Same.. no voltage on the same cables..Does someone have any idea what i can do to repair it? It's a 48 port gigabit switch, with POE on each port.. i don't wan't to throw it away..Thanks!
Cisco SF352-08P Reset Button - Page 1
Forum section: electronics / repair

author: pheonixzen700
author_rank: Newbie
timestamp: December 29, 2024, 12:14:57 am
content: I'm looking for a source for the reset button on a Cisco SF352-08P switch, so I can solder on a new one. SW5 printed on the circuit board. Any help would be appreciated. Thank you.
Clamp for glass LCD connection - Page 1
Forum section: electronics / repair

author: c36get
author_rank: Newbie
timestamp: July 14, 2024, 09:31:33 am
content: Hi,i have sucessfully repaired a glass LCD paper connection with a common ffc.For this i used a clamp from another LCD, as shown in the Pictures.Has anyone an idea how this clamp is named or where to buy it, except from old equipment?Cheers
Clamp Meter HT ITALIA HT-49 need schematic - Page 1
Forum section: electronics / repair

author: elianto
author_rank: Contributor
timestamp: September 24, 2025, 01:47:26 pm
content: Hi, don't fine anything in net about this clamp meter which I need to repair.Anyone with some manual/schematic ?Thanks in advance.

author: fant
author_rank: Contributor
timestamp: September 24, 2025, 08:27:46 pm
content: I have tried with some other instruments from HT, but no luck.They are impossible to find.If you will have more luck than me, please tell me where to search. I have the following instruments with an open heart on the bench:- HT M70- HT 8051- HT LOOPTEST 2014- HT RCDTEST 2012Thank you in advanceBest Regards
Clare V142 - Page 1
Forum section: electronics / repair

author: mendip_discovery
author_rank: Super Contributor
timestamp: July 04, 2020, 11:06:54 am
content: I think I need to get over to TEA and make a post soon.After a bit of a sober eBay session the other week I have a few standards to use for general checking. One of the items is these Clare V142 (V.142) units that were used to test Clare Flash Testers.I am looking for opinions for a way to clean up the brass connectors, I am tempted to remove them so that I can give them a damned good clean.OK, I removed one.

author: mendip_discovery
author_rank: Super Contributor
timestamp: July 04, 2020, 12:34:23 pm
content: A quick google suggested vinegar and some salt and let it soak for a few mins.So using an old spray can cap I first washed them in some Swarfega (Orange) hand degreaser, engineers will know the stuff.Then I mixed some salt in with the white vinegar I had. I left that while I made a cup of tea.Scary, it goes black and a quick rub with a nail brush and water and it looked dull.But with a very quick brush of a copper brush, it came up shiny. Now going to attack the rest of it.

author: Gyro
author_rank: Super Contributor
timestamp: July 04, 2020, 09:29:12 pm
content: Put a little Vaseline on the threads, it will prevent corrosion, improve conductivity, make them a lot smoother, and prevent then from binding over time.
Clarion 8204R Power, but no light, no sound, only dimmed numbers. - Page 1
Forum section: electronics / repair

author: darrentrrs
author_rank: Newbie
timestamp: January 18, 2023, 02:10:28 am
content: Best regards, I'm Darren from Mexico, I'm fixing a Clarion 8204R for my father, actually was a stereo with amplifier, but inside has this car stereo clarion, wasn't set to ground, so it was a high voltage and Bleu up the fuse on the amplifier and damaged the front panel, but I could fix it already, anyway the Clarion 8204R was also damaged, but still no way to fix it, since seems not physic damage only 3 capacitors 2 electrolytic and a ceramic one, I replaced the ceramic one and could have some interference sound, the two electrolytic capacitors seems kind of chubby on top, but seem to be working fine, I will replace them as soon as I can find them, but still no light or a working panel.Can somebody check out and tell me if has dealt with such situation?Thanks in advance and best regards.I will try to add some pictures, so can people check up.

author: darrentrrs
author_rank: Newbie
timestamp: January 18, 2023, 02:12:55 am
content: Here are more pictures

author: darrentrrs
author_rank: Newbie
timestamp: January 18, 2023, 02:20:47 am
content: The ceramic capacitor was replaced by a film capacitor (on the green arrow) and the two electrolytic around seem chubby (blue arrows), I will replace them as soon I can find some.

author: Jeff eelcr
author_rank: Frequent Contributor
timestamp: January 18, 2023, 03:31:35 pm
content: Check backlighting.Jeff

author: cantata.tech
author_rank: Regular Contributor
timestamp: January 19, 2023, 08:30:49 am
content: Clean and check the ribbon connector that goes to the lcd on the display.Sometimes these get dirty and/or damaged.There is a Cleaning spray that you can use to clean it.Use a multimeter and try to find out if the display is receiving power.Otherwise it might be a logic error.Maybe it's something different than being just a capacitor.
Clean Wavetek wafer switches? - Page 1
Forum section: electronics / repair

author: Axtman
author_rank: Regular Contributor
timestamp: December 17, 2022, 06:09:22 am
content: I recently acquired a Wavetek 164 sweep generator. What do recommend to clean the wafer switches? I know Tektronix used to recommend isopropyl alcohol. Thanks.

author: precaud
author_rank: Frequent Contributor
timestamp: December 17, 2022, 03:42:54 pm
content: Yeah, the Wavetek wafer switches are semi-enclosed. Squirting some IPA in and working the switch around should take care of it.

author: Testtech
author_rank: Regular Contributor
timestamp: December 17, 2022, 03:56:31 pm
content: Deoxit work best, apply through the holes in the plastic disc.

author: Axtman
author_rank: Regular Contributor
timestamp: December 17, 2022, 08:50:58 pm
content: I am a little nervous about using Deoxit. I had a piece of Heathkit test gear that I sprayed the wafer switches. I disolved the bakelite(?) and ruined the equipment.
Clean XFX Radeon RX580 GPU fan - Page 1
Forum section: electronics / repair

author: sorint
author_rank: Newbie
timestamp: November 14, 2019, 10:28:02 am
content: Hello. I have a lot of XFX Radeon RX580 and some of them have problems fith the spinning of the fans, in the sense that some do not spin anymire becouse of the dust. I have clean other fans but this ones are capsulated and have some gel inside. The only way i see to open them is to force them open, spilling the gel and rendering the fan useless.Do you know how the gel fans can be opened, or do you know where i could ask on this great www?

author: Muxr
author_rank: Super Contributor
timestamp: November 16, 2019, 12:43:28 am
content: Why not just replace them? I would reach out to XFX and see if they sell them.

author: sorint
author_rank: Newbie
timestamp: November 17, 2019, 09:28:22 pm
content: It to expensive. And the thing is i think it could be done

author: deadmanwalking
author_rank: Newbie
timestamp: November 18, 2019, 12:14:58 am
content: Unfortunatelly I'm not aware of any other way to fix GPUs fans 100% than replacing them.Some can be fixed temporally using WD40, but many fans are glued together and the WD40 separates the glue and turns some plastics brittle, destroying permanetly the fan.Maybe using a silicon based lubricant spray can help (the lubricating gel inside is silicon based), but I haven't tried it yet, can't tell if it's a good solution or even a temporally fix. By my experience not worth to fix the fans, beacause all of them die again (now for good) in a couple of months max. If you have many GPUs of the same model, maybe it's time to take working fans from the "better ones" to replace the broken ones in the most used/abused ones, then buy spares from ebay an place them in the "better ones". While you're in it you should replace thermal compound (I have a 20g MX-4 for CPU/GPU thermal paste re-aplying) and check/replace the silicon thermal pads.
Cleaning a Creative 5.1 5300 series remote - Page 1
Forum section: electronics / repair

author: TDA81
author_rank: Newbie
timestamp: August 08, 2020, 11:39:26 am
content: Hi, there!I'm having some trouble with my Creative 5.1 speaker set. The sound keeps failling, and sometimes it even powers down.From my research on the web, the problem lies with the remote. Theoretically, cleaning the potentiometer solves the problem. I'm thinking on cleaning it with isopropylic alchool, and then lube it. And here is my question:- What should I use to lube it?I've seen people using WD-40, not using WD-40, vaseline, silicone oil in spray... What's the "right" way to do it.Sorry for my english and for the basic question, but I'm just starting in electronics.NOTE: The photos attached are not from MY remote, but from one of the same model I've found on the web.Thanks in advance!

author: TheMG
author_rank: Frequent Contributor
timestamp: August 08, 2020, 07:32:51 pm
content: My go-to product for cleaning pots, switches, and other contacts is Deoxit D-5. You just spray it and work the pot back and forth a few times. Works wonders, I have not personally found any other product that works as good as this does.If you can't find the Deoxit, MG Chemicals Electrosolve contact cleaner works reasonably well, though doesn't seem to be as long-lasting as the Deoxit.For that matter, any electronics contact cleaner you can get will be better than any household product. They are specifically designed to not only clean but also remove any thin layer of oxidation on the contacts. Some also incorporate a small amount of lubricant suitable for electronics.Alcohol would wash away some of the dirt and grime but do absolutely nothing for any oxidation that may be preventing a good contact. I would avoid WD-40 in any pots, switches, etc. It can actually make things worst as it will coat all the parts in a very thin film of non-conductive oil. Definite no-no.

author: TDA81
author_rank: Newbie
timestamp: August 16, 2020, 04:58:40 pm
content: Thanks for the reply, TheMG.It seems we don't have Deoxit here in Portugal. However, I'll try to check the composition and find something similar.Thanks again!

author: james_s
author_rank: Super Contributor
timestamp: August 16, 2020, 05:15:34 pm
content: FaderLube is good stuff to use for cleaning potentiometers, I think it's made by the same company that makes DeOxit though. There are other various "control cleaner" products out there, they used to sell TV tuner cleaner that is essentially the same stuff but TVs with rotary knob tuning are antiques now.