hybridfree/eevblog-posts huggingface dataset:
Vintage Sony PLPS (SMPS) repair - Page 1
Forum section: electronics / repair

author: nyogo
author_rank: Newbie
timestamp: October 16, 2022, 08:00:48 pm
content: Hi!I'm restoring an old Sony TA-F6B amp(European model), the power supply kicked out the bucket. A cap at the regulator part blown up(C604), killed some transistors around it.Already replaced all caps, measured all transistors, I still have to check all resistors and diodes(but at first look they seems to be fine).The original 2SC2023Os at the inverter are fine, also Q605, Q606, Q607, Q608 are ok.The problem in the regulator part is with 2SC2023R (Q613), 2SC1810 (Q602), 2SA911 (Q603). I suspect that I should change all transistors in the regulator, at least Q601/Q613 to the same.I have a few 2SC2023 (without R or O letter) but still doesn't find any info about the lettered versions, so don't know whats the difference and why it is only R type allowed in the regulator and R or O at the inverter.(I found similar lettering for Fairchild KSC2335, where the R-O-Y mark the hFE classification and R stands for the lowest.)Also if I change 601/613 to simple 2023, would it affect the other part of the power supply?(sadly I don't have that kind of deep knowledge about electroics or SMPS/PLPS)Checked a few forums where some folks tried to repair same board with similar blown-cap caused issues, and it seems like the circuit is really sensitive for the right spec transistors.Found some old datasheet for 2SC1810 but nothing for 2SA911.It would be a really big help if someone could advice some replacements for 2SC2023R, 2SC1810, 2SA911. Maybe I could get some new old stock 2SC1810/2SA911 from eBay, but I would prefer some common off the shelf parts.Attached the schematic from the service manual, marked the bad transistors.
Vintage Synth (Hillwood C-1A) - identifying missing component - Page 1
Forum section: electronics / repair

author: tenka10
author_rank: Newbie
timestamp: April 24, 2021, 06:22:58 pm
content: I acquired aHillwood C-1A synthesizerwith a burnt circuit board with 3 empty holes where a part needs to go. I'd like to repair the board but I don't know what component to look for... Help?I've had one person suggest it might be either a large pass transistor or a voltage regulator IC in TO-220 package.
Viofo A229 duo dashcam front to rear cable coax - Page 1
Forum section: electronics / repair

author: bifferos
author_rank: Regular Contributor
timestamp: September 06, 2025, 02:59:06 pm
content: I have stuffed up the (MMCX I think) connector on my rear Viofo camera, trapping it in the tailgate when closing it. It did hang on for a while, but the center conductor is now completely messed up, and I'm in the unfortunate position that I have to decide whether to try to replace the whole cable or just put another connector on at the rear.Neither of these options are easy (for me at least).If I replace the cable, I need to feed the new one via the boot gator, which is a long and messy job, and I'll have to remove various bits of trim to do it. I also couldn't actually find the cable for this particular dashcam, I'd have to assume the cable for the new (A329 I think it is) dashcam is the same, and maybe order that.I did investigate putting a new MMCX connector on the 3mm coax. I couldn't find any of these supplied with boots. I don't have the crimp tool so would have to buy it, then I need to find the connectors. I wondered how feasible it is to solder these, they are very small and I'm wondering if it's going to be too difficult, especially working in the back of the car and not on the bench.Any advice for me? Many thanks!

author: thm_w
author_rank: Super Contributor
timestamp: September 08, 2025, 09:20:40 pm
content: Looks more like a MCX connector to me.You can buy the crimp tool for $10 the connector for $1-2 and then re terminate.Or the other option could be to buy an extension cable, chop it and solder it in place (google coax soldering, conductive tape can help to reintegrate the shield).Or terminate with SMA/BNC/etc and use an adapter.Soldering the connector is possible, but it won't be as strong without crimping the ferrule. They usually come with the ferrule here:https://www.aliexpress.com/item/1005007348277314.htmlLots of ways to do it.
Viper53 on a FreshAir II board does not start - Page 1
Forum section: electronics / repair

author: ignislion
author_rank: Contributor
timestamp: September 04, 2022, 03:31:04 pm
content: Good time of day!Currently I'm trying to recover the main board from the air purifier. The Viper53 power controller burned out with part of its binding. I found on the Internet a part of a very similar circuit and other people with the same board and was able to restore burnt part. However, the controller still does not start.The rectified voltage reaches the controller.COMP = 0.8TOVL~0VDD~10To start, the controller must charge the VDD capacitor to 11.5, but this does not happen and I still cannot understand why. And maybe I'm digging in the wrong direction at all. I would appreciate any comments, thanks!There is a lot of garbage in the photo, sorry, the board has been on the shelf for 2 weeks.https://oshwlab.com/wbnerd/fresh-air-ii-power-bdhttps://static.chipdip.ru/lib/004/DOC001004759.pdf

author: Andy Watson
author_rank: Super Contributor
timestamp: September 04, 2022, 03:53:55 pm
content: Is D10 short-circuit?

author: ignislion
author_rank: Contributor
timestamp: September 04, 2022, 03:54:53 pm
content: Diod was replaced it works fine

author: Andy Watson
author_rank: Super Contributor
timestamp: September 04, 2022, 10:29:04 pm
content: Oops! I had missed the VDD=10 and read it as VDD= 0.Does VDD remain stable or does it pulse regularly? If it pulses, it suggests that the Viper53 is trying to start-up, but is being held-back by something.The PCB around the Viper53 appears to have suffered some significant heat! I suspect that chip's demise was probably a symptom; not a cause. Could be just a trick of the light, however, there is a PCB track that starts under R44 and travels north-east towards the low voltage test-points - looks like it has been over-heating. If this is so, that current must have originated in the transformer - i.e. it is highly likely that that is fried too - probably taking the Viper53 with it.

author: ignislion
author_rank: Contributor
timestamp: September 05, 2022, 10:52:52 am
content: Sorry! I may need to attach an image of how the board looked at start. The components were literraly roasted and blowed. So i replaced everything in regulator and loopback parts.

author: ignislion
author_rank: Contributor
timestamp: September 05, 2022, 10:54:04 am
content: IC8 - optocoupler was dead so i replaced it and anything near as well.
Visio D48-Do LED TV no Power - Page 1
Forum section: electronics / repair

author: Mandy
author_rank: Newbie
timestamp: June 24, 2021, 08:26:57 pm
content: I have a Visio D48-D0 LED TV, TV was strobing so replaced both boards now it brings up Visio logo for 5 seconds then powers off, replaced boards again same outcome, put in old board it started strobing. What could problem be?

author: fzabkar
author_rank: Super Contributor
timestamp: June 24, 2021, 10:57:40 pm
content: Does it still power off if you disconnect the LEDs?
Vision Engineering Mantis Base Piece - Page 1
Forum section: electronics / repair

author: ZGoode
author_rank: Frequent Contributor
timestamp: March 06, 2025, 11:15:09 pm
content: Howdy Y'all,I have an original Vision Engineering Mantis which is complete (with a x6 EW and x10 lens), just missing the base piece. I am hoping someone located in the USA would be willing to lend me theirs if they have the right piece so I can 3d scan it to create a CAD model which I can then either replicate in Nylon using SLS or machine out of Aluminum. Or if someone has already gone through something similar and has a CAD model. I did find a post earlier where it seems like this is a very difficult, if not impossible, part to get a replacement for.According to the manual I found over on manualslib, I am looking for part #5 (187-B-0090)https://www.manualslib.com/manual/2304760/Vision-Engineering-Mantis.html?page=4#manual

author: thm_w
author_rank: Super Contributor
timestamp: March 06, 2025, 11:57:17 pm
content: I wouldn't bother 3D scanning something like this. Design for its intended function, should be a few simple cylinders and holes.Looks like someone has already done it here:https://hackaday.com/2018/02/05/repairing-a-wounded-mantis/#comment-6727943

author: Bud
author_rank: Super Contributor
timestamp: March 07, 2025, 01:25:34 am
content: Another one?https://www.thingiverse.com/thing:6605593
Vision Scientific Microscope Reviews - Page 1
Forum section: electronics / repair

author: roy_eedreku
author_rank: Contributor
timestamp: April 09, 2020, 08:21:57 pm
content: Hey folks.I have been in the market for a micro soldering microscope. We use Amscope single arm boom stand microscope at work. Amscopes are fairly pricy. I found this company called Vision Scientific selling similar spec microscopes but for lot cheaper. I am trying to target theVS-3FZ-IFR07which is close to $200 cheaper than the Amscope of the same specs.Amscope is heavily recommended by everyone in the repair industry. I unfortunately, can't find too many reviews about Vision Scientific to make an informed decision. I don't mind spending the extra and getting the Amscope but almost half the price on the Vision Scientific is very appealing.If anybody has any experience using Vision Scientific, please let me know. Any good or bad experiences would be highly appreciated.Thanks!

author: jfiresto
author_rank: Frequent Contributor
timestamp: April 11, 2020, 12:17:11 pm
content: I largely buy used microscope equipment, built decades ago for decades of use, from sellers who often do not know what they are selling and, once in an unavoidable while, from sellers who do know and are not forthright about their wares.I know nothing about Vision Scientific, but looked over their website, reflected on my experiences and imagined how things could go. I, myself, would look elsewhere. I found too many ways I could receive a pig a in a poke and pay for the experience.

author: aqibi2000
author_rank: Regular Contributor
timestamp: April 11, 2020, 12:53:33 pm
content: I would recommend getting x10 optics and a x 0.8 to 4 adjustable lens I stuck a Barlow x0.5 lens on the end of mine to get awesome working distance.As and above I *scored* this Nikkon branded microscope with boom stand cheap on the only important website in the world... it may be a decade old lacking a video feed but that’s not important.

author: jfiresto
author_rank: Frequent Contributor
timestamp: April 11, 2020, 01:06:56 pm
content: What model Nikon (not Nikkon?)?

author: jfiresto
author_rank: Frequent Contributor
timestamp: April 11, 2020, 05:11:53 pm
content: I see Amazon sells theVS-3FZ-IFR07along withtwovariantson handier, twin-arm boom stands. Vision Scientific only gives you seven (7) days from receipt to inform them, if you order directly from them and wish to return the microscope. That is not much time to find issues.
Vita Audio R1 Mark 2 backlight very dim in standby - Page 1
Forum section: electronics / repair

author: Jeffery
author_rank: Newbie
timestamp: November 27, 2024, 05:24:47 pm
content: Hello all, I'm a newbie and I'd very much appreciate help with the following.In standby mode, the display of my Vita Audio (Ruark) R1 Mark 2 is very dim, it gradually faded over a period of a few weeks. However, when switched on, it appears normal and responds to ambient light levels as before. All display LEDs appear to be working normally. Any help would be greatly appreciated.

author: rh100605
author_rank: Regular Contributor
timestamp: November 29, 2024, 03:52:03 pm
content: JefferyCan I assume that you have adjusted the standby backlight in the System menu and still have a problem ?If the LCD backlight works fine in switched on mode, then a firmware update can solve the problem. I can supply the code if you can remove / replace the flash memory chip on the DAB module and re flash it.

author: Jeffery
author_rank: Newbie
timestamp: November 29, 2024, 04:57:46 pm
content: Yes Rob, the backlight is set to auto in the system menu rather than a fixed time. Thank you for your kind offer but I think I 'flashing' etc. is well beyond my expertise. Nevertheless, your post is much appreciated.Regards, Jeffery

author: rh100605
author_rank: Regular Contributor
timestamp: December 01, 2024, 07:42:26 pm
content: JefferyThanks for confirming that your system menu does not have a "Backlight Stby" option after the "Backlight" option,and that your Software version is FS2027-0000-0054_V4.0.13.27373-1RC2The Software version I have in my R1-Mk2 is FS2027-0000-0054_V4.2.11.38059-2RC1 and has a Backlight standby brightness option,I can supply you with this Flash memory image or even a chip with it burnt in but you would have to remove and replace the chip inside the FS2027 DAB module, which you have said is too complicated.The other alternative is to remove the whole DAB module from the radio and send it to me for upgrading.As to why this has occurred , I think the display backlight LEDs are dimming with age. They can be replaced however changing the code to give you more control over led intensity in standby is a safer option.I do not have access to Ruark software that would use the USB port to flash the firmware.Maybe someone else reading this has the Ruark Windows firmware update application ?For others reading this the Flash images are now attached.Older R1 Mk2 image made on 8th Oct 24 FS2027-0000-0054_4.0.13.27373-2RC2Newer R1 Mk2 image made on Oct 23 FS2027-0000-0054_4.2.11.38059-1RC13Best wishes
Vita Audio / Ruark R1 Mk1 Radio - No Sound - Page 1
Forum section: electronics / repair

author: MelJ
author_rank: Newbie
timestamp: February 05, 2024, 01:13:49 pm
content: Hi All,I bought this unit in non working condition described as "does everything but no sound". It sounded like a final amplifier problem so I thought it would be any easy fix. There was indeed a final amp problem due to some bodged repair work in this area and this was easily fixed. Disappointingly the unit still wouldn't work because no audio signal was getting to the final amp (TDA7266). The Gyro-1122 DAB unit feeds a PT2314 audio processor and then to the TDA7266. The Gyro-1122, the LCD display and the PT2314 communicate via the I2C protocol. I had no previous experience with I2C but a bit of homework to find out the basics and some searching to find the I2C address for the PT2314 (fixed at 10001000) and I was able to make a start. Some probing of the PT2314 I2C clock and data lines revealed that both lines seemed to be behaving as expected but the PT2314 was not acknowledging I2C requests. The PT2314 had to be replaced. I can only guess that the PT2314 failure was due to the bodged repair job around the TDA7266 shorting its outputs so it's probably not a typical failure in these units.The original PT2314 chips are readily available in the UK but are very expensive. The newer (and fully compatible) PT2314E version is readily available from China cheaply but make sure you use a reputable supplier. The replacement of the 28 pin chip was straightforward, despite my initial trepidation!The Ruark now works perfectly so it's a repair that's worth taking on. The R1 Mk2 uses the same audio chip and final amp but the DAB unit appears to be different. More details about the diagnosis and repair can be found in my posts on the UK Vintage Radio Forum.CheersMel

author: rh100605
author_rank: Regular Contributor
timestamp: February 10, 2024, 11:00:15 am
content: Mel,To make it clear to other readers, the R1 Mk1 radio cannot receive DAB+. This results in stations being tuned but no sound.This would seem to be a fault similar to the one described in your post but is not.The R1 Mk1 uses the Gyro 1122 DAB module and vAN 1.0 flash code in a parallel flash chip. It has a 2x16 LCD parallel connected LCD type 1602 EThe R1 Mk2 with a larger custom SPI LCD uses either the FS2027 DAB module or the later Gyro 1128 DAB module with 25 series flash memory and vAN 1.2 code.The 1128 DAB module is used in the R2i and R4i. All receive DAB+ stationsIn case readers think a flash code upgrade may allow the Mk1 to receive DAB+, the hardware differences between the Mk1 and Mk2 make using the 1.2 flash code in a Mk1 to receive DAB+ impractical even if the processors were the same..
Vitramon Brand Capacitors? - Page 1
Forum section: electronics / repair

author: edpalmer42
author_rank: Super Contributor
timestamp: April 05, 2020, 03:35:24 am
content: I'm refurbishing a piece of 1960's vintage equipment. A few of the critical capacitors appear to be from a company called Vitramon. I'm having trouble finding good info on them because Vishay bought the name and are now producing capacitors under that name. This creates a lot of noise in the Googleverse.Does anyone have any specs on the OLD Vitramon capacitors? In particular, I'm looking for info on temperature coefficient and tolerance.Thanks,Ed

author: andy3055
author_rank: Super Contributor
timestamp: April 05, 2020, 03:51:15 am
content: You can probably contact these people:https://www.surplussales.com/capacitors/RF-Vitramon.html

author: edpalmer42
author_rank: Super Contributor
timestamp: April 06, 2020, 05:22:22 am
content: Yes, I found that site. It was the site that first gave me the brand name. Since I'm not buying any capacitors right now, I don't like to take up their time by asking them questions.Ed

author: andy3055
author_rank: Super Contributor
timestamp: April 07, 2020, 03:19:01 am
content: You need not buy anything right away. You can ask for a catalog of some sort if they have and probably establish communication with someone there and see how it goes. May be you can email some pictures of the items you have/need and see how that goes. If a seller can't bother answering your questions, you have to look elsewhere (they know this anyway).
Vizio E48-D0 Malfunction. - Page 1
Forum section: electronics / repair

author: Stubbornazz
author_rank: Newbie
timestamp: July 18, 2019, 07:23:32 pm
content: Good day,I have a Vizio E48-D0 flatscreen TV, initial issue was no pic or sound. Ordered a complete LED TV repair kit (KIT-E48-D0-K1). Received kit and replaced both power board and main board. Powered TV up and screen powered up weird, as in Vizio symbol only showed up partly then went to blank screen. Swapped main board back to original and powered up TV. After powering up twice, screen worked properly. Hooked up HDMI for cable TV and all worked perfectly. Then next day turned on TV, worked fine at first then went to blank screen with only audio working. So my question is this, any idea what needs to be done or should do? Thank you.

author: fzabkar
author_rank: Super Contributor
timestamp: July 18, 2019, 10:49:04 pm
content: Could it be a backlight inverter problem? Can you see the video if you shine a torch at the screen?

author: Stubbornazz
author_rank: Newbie
timestamp: July 19, 2019, 04:27:56 pm
content: No it does not seem to be a backlight issue. There is a white-ish colored sot on the bottom left corner of the screen. This was never there prior to changing boards.

author: shakalnokturn
author_rank: Super Contributor
timestamp: July 19, 2019, 10:01:31 pm
content: One of the bias voltages gone intermittent on the T-con board?

author: Stubbornazz
author_rank: Newbie
timestamp: July 20, 2019, 02:45:38 am
content: I'm sorry to say this but I'm not sure how to check for that. Nor can I even find a replacement t-con board for this TV. From what I've watched and read it appears that this could be the issue. Because I do have backlights and audio, just no pic.
Vizio LED TV Repair Model E50-C1 - Page 1
Forum section: electronics / repair

author: clocklin
author_rank: Newbie
timestamp: April 30, 2020, 12:03:41 am
content: I have a Vizio model E50-C1 LED TV thathas backlight, hasNO sound,has a Black Screenand theStandby light on the front works propertly. My research online led me to believe that that either the Main board or the T-Con board was bad. I went to Shop Jimmy and ordered all three boards, Power, Main & T-con as that seemed to be the best deal. I first replaced the main board with no success. Next I replaced the T-Con board next with no success. Then because I already had the board, I replaced the Power Board. NO SUCCESS! The TV has two additional very small PC boards that were not mentioned anywhere I researched and were not offered as a repair part on Shop Jimmy. I have attached a pic of these two small boards. I am wondering if one of these could be the problem. Any help would be greatly appreciated. I've got 60 dollars invested so far so I don't want to trash the TV.

author: Manul
author_rank: Super Contributor
timestamp: April 30, 2020, 12:21:21 am
content: That looks like WiFi board and some adapter for it. You may try to disconnect both of them, see what happens. I think that they are not even necessary for TV to start (but who knows). You have a strange situation.

author: clocklin
author_rank: Newbie
timestamp: April 30, 2020, 12:30:29 pm
content: Thanks Manul for your input!
Vizio M658-G1 keeps rebooting - Page 1
Forum section: electronics / repair

author: Miti
author_rank: Super Contributor
timestamp: February 17, 2024, 01:58:05 am
content: I've got a Vizio 65" M658-G1 that keeps rebooting. It takes forever to get to the logo, about 55 seconds, then the logo goes away, the backlight stays on for awhile, then reboots. From my research apparently is the firmware that gets corrupted and I need to replace the NAND or the EMMC, whatever this one has.Do you know where I can find the programming file for this?Cheers,Miti

author: Miti
author_rank: Super Contributor
timestamp: February 18, 2024, 12:49:20 am
content: In the end I bought a main board from Ebay, picked up 10 Km from where I live. The TV is back in business.Now I want to see if I can fix the bad MB.

author: Miti
author_rank: Super Contributor
timestamp: March 06, 2024, 09:39:03 pm
content: I still want to repair this board. Do you think that the EMMC is defective or it may be just corrupted? What’s the most common failure mode of an EMMC? I’m thinking maybe it crashed during a SW update.If I put the SW on a USB stick and power on, do you think it may detect the corruption and load from the stick or it needs to be in some kind of bootloader mode?The procedure for loading from the USB stick requires it to start and select an input that doesn’t have signal. Obviously I can’t get to that point.Cheers,Miti
Vizio Soundbar Subwoofer board! - Page 1
Forum section: electronics / repair

author: crshovrd
author_rank: Newbie
timestamp: May 14, 2020, 09:16:55 pm
content: Hi all,I noticed my woofer stopped working, so I tore it down and probed it. No voltage to the required parts of the board! I pulled one of the SMD caps off the board to probe it directly and it seemed good. So I put it back. I then noticed a burned trace up to an IC, so I pulled the IC off the board. Unfortunately, I ended up burning off 3 of the leads of the IC when I pulled it off the board... me an my radio shack iron lol...Anyway, hoping someone could help me identify the IC because I've scoured the internet and the top mark isn't any where to be found. Also, if there is someone that can look at the circuit and possibly recommend a replacement part, that would be awesome! Thanks in advance!!Also, don't mind the tortured smd cap, it still works. Also, there was still flux on the board when I took this pic, hence the discoloration.EDIT: Forgot to mention that the two bottom legs from the left read 24V DC. So, I would imagine that Vcc is 24V on whatever this chip is.
Vizio TV e701i-a3 No pic but backlight and t-con changed - Page 1
Forum section: electronics / repair

author: Serge125
author_rank: Regular Contributor
timestamp: September 10, 2023, 01:26:52 pm
content: Hi all!! Ok I was given a Vizio e701i-a3 tv and the problem is no pic BUT it has sound and backlight. So I changed the t-con same problem so started to probe voltage on PS connector to main board and all is ok BUT one part that I'm not sure is that on the t-con fuse I get 1.xx volts, isn't it suppose to get 12v?? For now I suspect maybe the main board BUT again it could be the lcd panel. So where do I go to check the main board not much pin info on this one compared to the PS so it's a guessing game here since no service manual (up to now in my searches). So I'm open for tips and suggestions.THANKS in advance!!!
Vizio VX37L HDTV-V10A - Page 1
Forum section: electronics / repair

author: Hextejas
author_rank: Frequent Contributor
timestamp: June 11, 2019, 01:45:46 pm
content: Hi.I got this beast for free so it is worth a try at repairing it.I plugged it in and it powers up ok, I think. At least I can get the screen to light up.However,All the stuff I am trying below is through the remote controller, as the buttons on the side seem dead.The TV acts as if the menu button on the remote were glued down as it continually cycles through all the main selections.( I didn't think to take the remote apart and see whats up with that button, if anything. I will do so. )At one point I was able to pause it momentarily so as to select the antenna as input and to auto scan for stations.That worked for a bit and I can see that I can tune an accurate picture. No sound though as I cannot get the menus to stop cycling so as to be able to select the onboard sound.I have the cover off and have just begun to poke around in it.I am assuming the power supply is good as the screen lights up ok and the picture is good.Many thanks and all suggestions are welcome.

author: Hextejas
author_rank: Frequent Contributor
timestamp: June 11, 2019, 02:41:27 pm
content: Is it probable or likely that the IR controller board is bad ?
VNA Damaged Front-End Characteristics? - Page 1
Forum section: electronics / repair

author: fourierpwn
author_rank: Regular Contributor
timestamp: September 29, 2020, 12:10:39 pm
content: Hi all,A general question, what would one typically expect to see on the display (ports floating) if the input section of a VNA was blown due to being overdriven? I am trying to pre-diagnose a faulty VNA before potentially committing to the purchase but I'm quite cautious of what the fault may be. There is a warning message on the display which says that the test ports are overloaded yet both ports are floating and S11 has a few notches across the sweep.Thanks!

author: joeqsmith
author_rank: Super Contributor
timestamp: September 29, 2020, 01:07:09 pm
content: I bought a few things over the years that had damaged front ends. Looking at the inputs, they no longer measure 50 ohms. Then you take them apart and see the carnage. I had an SA that they must have locked out the attenuator and actually took out the mixer. I always envision some amateur radio or CBer thinking they are a EE, trying to measure their output power or response of their new Japanese gear.The last VNA I bought had been damaged. It was hot enough to discolor some of the metal. Depending what you bought, if it was sold "working" I would just return it. You may find the costs to repair it are very high or you just can't get parts. If you do decide to keep it and pull it down, take a few pictures. If you decide to open it up, I would check with the seller first. You may not be able to return it if you open it. Of course, if we are talking $100 or $50,000 it makes a difference. So does your skill, education, tools available and aversion to risk.

author: Bud
author_rank: Super Contributor
timestamp: September 29, 2020, 01:38:51 pm
content: If you have access to the VNA in question and another VNA, measure the Return Loss of the test ports.You are not indicating the damaged VNA model. Industrial high frequency VNAs have custom parts in the test ports which you will unlikely be able to repair unless the entire test port assembly is replaced.
Volktek INS-802 Industrial Poe+ Injector Switch in Startup Loop - Page 1
Forum section: electronics / repair

author: Fried Chicken
author_rank: Regular Contributor
timestamp: March 22, 2024, 10:39:35 pm
content: I have a Volktek INS-802 Power Injector/ethernet switch that has lived in my attic for the past four years or so that's started giving me problems.At first it the access points attached to it started bitching about not enough power, then it would post but give some sort of alarm (I'm not sure what that was since I've never been able to set an IP address without it resetting with a power cycle, not that it was a problem), and now when I plug it in it goes into some sort of boot loop with a relay clicking.This poor industrial poe switch has had a hard life, first coming from some mining company in alaska, and then living in a hellish texas attic. Still all within its rated capacity.Anyway, I'm going to tear into it soon and see if I can figure out the problem. I thought I'd go ahead and post here and post more information as I start tearing into it.

author: Fried Chicken
author_rank: Regular Contributor
timestamp: March 23, 2024, 10:45:51 pm
content: I gave up.There were 2 capacitors that I removed and tested good. Lead free solder is a disaster. Put it back together and the same clicking problem.Pics of the board in case anyone might be interested.

author: m k
author_rank: Super Contributor
timestamp: March 29, 2024, 02:10:19 pm
content: Pretty integrated these things nowadays.Maybe new device to a bit cooler environment has a positive long term result.Maybe a DIP switch or two have lost their nerv.

author: Fried Chicken
author_rank: Regular Contributor
timestamp: March 29, 2024, 04:47:32 pm
content: Quote from: m k on March 29, 2024, 02:10:19 pmI got a new switch for cheap, this one is gonna end up in the trash, but I might keep the capacitors in it. They tested better than capacitors I've ever seen. My meter gave an ESR of 0 (it's not a good meter)
Voltcraft DSO6204F - Page 1
Forum section: electronics / repair

author: omega12
author_rank: Contributor
timestamp: August 03, 2025, 10:34:50 pm
content: Hello,I received a defective oscilloscope as a gift and I would like to try to repair it.When I press the on button, nothing happens. If I press and hold the on button, a few LEDs light up and the fan runs, but nothing can be seen on the display.I removed the battery because it only had 1.2V and seemed to be oxidized.The power supply unit is ok and supplies a stable 5.5V.On the motherboard it says XDS_4CH_HM2_V1.1.1 and I think it should be an OWON XDS, but I'm not sure.On the one picture you can see that there is an IC missing but I think that will be the IC for the version with the multimeter.Can someone please help me?Thanks, omega12

author: J-R
author_rank: Super Contributor
timestamp: August 04, 2025, 12:51:23 am
content: Yes, that does look very similar to my Owon XDS. On my unit, you do need to hold the power button down for a couple seconds to get it to boot. Just pressing it or pressing and holding briefly will not work.So I guess my only contribution at the moment is: what happens if you continue to hold the power button?

author: omega12
author_rank: Contributor
timestamp: August 07, 2025, 09:24:01 pm
content: Hello J-R,When I press and hold the button, a few LEDs and the fan turn on, but nothing appears on the display. Even if I hold the button down longer, nothing happens, and when I release the On button, everything turns off again.Regards, omega12
Voltage and resistance measurment are wrong in HT118A - Page 1
Forum section: electronics / repair

author: eli120
author_rank: Newbie
timestamp: December 24, 2021, 01:34:37 pm
content: Hi all,I got this DMM for about 3 weeks and used it only a few times.Anyway, a few days ago I noticed that the voltage reading are 10 times higher than it should be.And the resistance measurment shows 87 ohm when the probes are not measuring anything, in fact it shows 87 ohm even if the probes are disconnected.I opened the DMM and looked for something burned or shorts on the PCB such as the resistors diveders and capacitors but didn't find such.And the rest of the functions- mA, capacitance, temp are working fine.I also clened the PCB with Alcohol but didn't help.* the seller offered to refund me, but I want to fix it(atleast to try)Any ideas to what to do next?thanks

author: abdulbadii
author_rank: Frequent Contributor
timestamp: December 24, 2021, 03:23:55 pm
content: refund itit's a failed quality control in R for V range and few comp. else

author: mzacharias
author_rank: Frequent Contributor
timestamp: December 24, 2021, 03:24:39 pm
content: Normally symptoms like this don't occur naturally - the meter was blown by overvoltage of some sort.Get it exchanged or refunded. If not, you'll need another meter to try to troubleshoot.Start by measuring the input impedance of the Volt-Ohm jack with respect to the common jack. Should read 10 to 11 MegOhms.I'm guessing it will read less.

author: eli120
author_rank: Newbie
timestamp: December 24, 2021, 05:21:07 pm
content: Quote from: mzacharias on December 24, 2021, 03:24:39 pmI checked with another DMM(also cheap but that's what I have right now) and I got ~13.5M ohmI checked with a cheap ESR meter and I got 12M ohm between the terminals.anyway, all the measurment I done were in range of the device.Quote from: abdulbadii on December 24, 2021, 03:23:55 pmthe seller said he will refund me and also said I could try to fix it or give it to someone to fix it.And the main reason I want to try to fix it, it's mainlly because it got all the functions I need and seems to be preety accuarte(according to reviews online)- just for home testing here and there.And also because it was preety cheap- I'm a student so I'm on budget right now.Thnks

author: Dr_McFish
author_rank: Newbie
timestamp: July 06, 2022, 05:01:58 pm
content: I have the same issue: it was working fine before, then then suddenly the volatage messurements are like 10x higher. 9V battery messures 116V

author: normanski
author_rank: Newbie
timestamp: April 11, 2025, 06:15:42 am
content: Hi guys,My HT118A developed the same problem. I had also opened and checked for the usual blown parts and dry joints but failed to see anything obvious. That is until I saw the Calibration video on YouTube, and my meter is working again.Perhaps it is now common knowledge to the community. But since I see no reply to this issue, I thought I would post it. I saved my meter from the landfill. Hope it helps.RegardsNorman,
Voltage issue on a Yamaha Tyros 2 keys matrix scanning board  - Page 1
Forum section: electronics / repair

author: dariodario
author_rank: Contributor
timestamp: February 03, 2023, 06:26:30 pm
content: Hi, I'm trying to repair a Yamaha tyros 2 keyboard.The problem is that all the couples the D# - A keys sound only the first time I press them. The second time I press them they don't sound anymore. The D# and A are on the same wires in the matrix scan as you can see from the attached schematics.There is no interruption in the circuit D#-A (in fact the first time they sound) but some oxidation points.I noticed (with reference to the attached schematic) that the pull-up 5V voltage in the EMKS-F board is present on all scan lines except on the D#-A line. In the D#-A line are present 1.1 V instead of 5 V. So this could be the reason of the D#-A not working keys.With the board disconnected, I also noticed that measuring the resistance from the 5V line to the scan lines, all are about 32-33 Kohm (OK, as per schematic R30..R41), except on the D#-A line in which I measure about 20 Kohm. Unfortunately I cannot access to the hide layer of the board due to 2 connector that are difficult to desolder. That 33K smd resistors are on the hidden layer of the board.Shouldn't I have 5 volt even if the SMD resistor changed its value from 33K to 20K, since it is connected as pull-up resistor?Some suggestions please for desoldering this difficult connectors whitout damage the two layer board? The problem is that I need to remove the two at the same time to push out the board...Thanks a lot.Regards.

author: Audiorepair
author_rank: Frequent Contributor
timestamp: February 04, 2023, 07:06:19 pm
content: Quote from: dariodario on February 03, 2023, 06:26:30 pmWell yes you should.The most common problem with key PCBs is someone spilt something onto the keys and it leaked onto the PCB.It sounds like you have a partial short to ground on this line, so look very carefully for any traces of liquid damage by following the line as best you can.

author: dariodario
author_rank: Contributor
timestamp: February 06, 2023, 03:31:21 pm
content: Audiorepair, you are right.I cutted the main trace (D#-A) near the connector, and now the line is generating 5V as expected!The problem now is finding the point of the partial short to ground, since 1/3 of the circuit is covered by the scanning board...and just this 1/3 has the most number of vias. I think that the partial short is on one of that vias due to the nearness with the ground (shaped ground layer) and the oxidation I saw on that.Regards.
Voltage pot BK 1670 - Page 1
Forum section: electronics / repair

author: Audiofanman
author_rank: Contributor
timestamp: December 04, 2023, 07:10:06 pm
content: Like many others i find my voltage adjustment pot too sensitive..Im taking an educated guess its the 50k VR2 potFound in ...https://www.eevblog.com/forum/chat/bk-precision-good-customer-service/?action=dlattach;attach=26074My question is what wattage should I be looking for in a 10 or 3 turn replacement?Thanks for the help!Edit;Added the owners manual...

author: Swake
author_rank: Frequent Contributor
timestamp: December 05, 2023, 07:32:21 am
content: Cant open the schematic right now but I do not expect the pot having any specific power requirement. You might consider putting another smaller pot (5k) in series if the front allows for this. In use this is many times quicker especially if you want to go all the other way of the range.

author: Audiofanman
author_rank: Contributor
timestamp: December 06, 2023, 01:53:15 am
content: Thanks for the reply, my feed proves that AI is listening.... A video poped up an hour or so later with someone who had an old large 1k 10 turn pot in series and a huge metal dial allowing super fine control... ebay has something on its way...

author: coromonadalix
author_rank: Super Contributor
timestamp: December 06, 2023, 04:12:56 pm
content: you have the classic 10 turns and the 20 turns who take months to turn lollyeah something like 10k normal turn with an 1k multi turn to adjust with precision ....but some people are confusing linear with logarithmic models, they have some surprises when dialing values ....
Voltage regulator replaced but still not working - Page 1
Forum section: electronics / repair

author: Marmotta
author_rank: Contributor
timestamp: November 15, 2022, 03:19:47 pm
content: I've got a device that runs on USB VBUS 5V and sends 3.3V and 1.2V to the ICs on the board through a couple of regulators. However, the CY7C68013-56 chip is not being detected when inserted into my PC and on further inspection it seem the 3.3V voltage regulator has a 5V input and is connected to ground, but isn't outputting anything at all (note the 1.2V reg is working fine). I swapped out the regulator for another I had on hand, but the same issue is still happening.I think I have a schematic of the board attached (or at least one that is very similar), any ideas what other components could be causing the regulator to fail? I've had a cursory look for shorts and didn't find any, but will check it over again, as well as see if the board will power up with 3.3V applied independently.

author: thm_w
author_rank: Super Contributor
timestamp: November 15, 2022, 11:23:30 pm
content: Could be a capacitor or IC shorted to ground on 3v3 output.When you measured the 3.3V rail, resistance to ground was what?As you said, next step can be injecting 3.3V, preferably start low and dial up the voltage, with a current limit of ~300mA. If current limit exceeded, poke around to see if anything is getting hot or if you can narrow down the short with voltage drop measurements.

author: DavidAlfa
author_rank: Super Contributor
timestamp: November 15, 2022, 11:35:40 pm
content: If there was a short at the input, you wouldn't have 1.2V, so it must be at the output.The LDO should be getting warm.Check there're no solder bridges between the CY7C VDD/GND pins.
Voltcraft CPPS-160-42/Manson SSP-8160 power supply repair firmware - Page 1
Forum section: electronics / repair

author: Pluscrafter
author_rank: Regular Contributor
timestamp: December 11, 2019, 03:22:43 pm
content: I've bought an defect Voltcraft CPPS-160-42 for 20Fr. and found out that the microcontroller of the frontend is shorted/destroyed. It is a NXP LPC2132FBD64. Is there any chance to repair and get the hex file for that chip? Or could I get the frontend board from somewhere? It's the same power supply like theManson SSP 8160https://www.reichelt.de/labornetzgeraet-0-42-v-0-10-a-stabilisiert-programmierbar-ssp-8160-p142094.html?&trstct=pol_1Original Voltcraft CPPS-160-42https://www.conrad.de/de/p/voltcraft-cpps-160-42-labornetzgeraet-einstellbar-0-02-42-v-dc-0-01-10-a-160-w-usb-fernsteuerbar-programmierbar-a-1182100.html
VOLTCRAFT DSO-1204F Oscilloscope - Page 1
Forum section: electronics / repair

author: Oleh UA
author_rank: Newbie
timestamp: March 17, 2023, 06:00:12 pm
content: Hi all! I was lucky to become the owner of a non-working VOLTCRAFT DSO-1204F oscilloscopethe problem is that it is not loaded into the system, but what is interesting is that once it is loadedto the VOLTCRAFT logo, then the recovery menu when you press F2, it goes to be restored, butin process error Operation Failed! and if you turn it off and on, then it loads up tothe Hantek logo with the kuar code and hangs tightly, it seems that they tried to update itfile from HantekLogi counted in all three variants:1 before loading with Hantek logo2 before loading with VOLTCRAFT logo3 after F2I'm asking for your help, as this is the first time I've come across this kind of technology.Thank you very much!
VOLTCRAFT LSP-1363 or LSP-1205 - Page 1
Forum section: electronics / repair

author: dam234
author_rank: Newbie
timestamp: December 23, 2020, 05:27:14 pm
content: I am looking for firmware for the PIC18F87K90 microcontroller with the VOLTCRAFT LSP-1363 or LSP-1205 power supply.Preferably version R1.7 or R1.5The micontontroller is unlocked.It is possible that the same microcontroller is in Manson NSP-3630 or NSP2050Please help
Voltcraft LSP 1363 Power Supply - no Output - Page 1
Forum section: electronics / repair

author: ULY
author_rank: Newbie
timestamp: June 03, 2016, 01:09:05 pm
content: Hi there,I have a broken Power Supply namedVoltcraft LSP 1363it seems to be a clone of theManson NSP 3630It powers up, I can set a Voltage and Current, but the output stays 0V and it displays 0V- No Visual damages- checked TransforatorsDoes anyone has a Service Manual or any Hint, where to start?

author: dundee
author_rank: Regular Contributor
timestamp: June 03, 2016, 10:32:10 pm
content: This should be the schematic for the device:http://www.produktinfo.conrad.com/datenblaetter/500000-524999/515266-sp-01-en-VOLTCRAFT_LSP_1363_LABOR_NETZGERAET_100W.pdfD10A or D10B bad? Also check the mosfets.

author: Strada916
author_rank: Frequent Contributor
timestamp: June 04, 2016, 12:29:28 am
content: check the following are working U1, q2, q3, q7, q8, q10 & q11I would check all the supply voltages first to ensure no voltages are missing. I would then start with q10 & q11 and go back

author: dam234
author_rank: Newbie
timestamp: October 13, 2020, 01:05:14 pm
content: Does anyone have the PIC18F87K90 MCU firmware for the VOLTCRAFT LSP-1363 power supply.MCU is unlocked so you can read.

author: coromonadalix
author_rank: Super Contributor
timestamp: October 13, 2020, 02:21:33 pm
content: Quote from: dundee on June 03, 2016, 10:32:10 pmlink doesnt open or it download an empty pdf ??okay got it, you have to search LSP 1363Yep would be nice to have the pic dump

author: coromonadalix
author_rank: Super Contributor
timestamp: October 13, 2020, 05:08:48 pm
content: @ ULY do you enable the output with the button on the front panel ?? you have the output on/off button
Voltcraft MF-90 - material moisture meter showing 0% - Page 1
Forum section: electronics / repair

author: shianne
author_rank: Contributor
timestamp: December 21, 2022, 03:30:26 pm
content: Hello,colleagues have brought over a material moisture meter type Voltcraft MF-90. Error description: It is always displayed 0%.The oscilloscope indicates that there is no signal at the sensor tip. After opening, this can also be confirmed at transistor Q5. Q5 seems to belong to the oscillator.Specific tapping with the wet fingertip showed that the main IC seems to measure in principle.My first guess was a defective Q5 (maybe ESD). It says BF199 on it, so I assume it is a BF199 (Q5-BF199.jpg). Measurements with the diode tester are confusing - there must be something defective.Still, it looks more like PNP than NPN... (Voltcraft-MF90-BF199-diodetest.jpg)Does anyone have an explanation?A test with a SF245 (GDR replacement type ) showed no oscillations too. So I draw out the circuit diagram after all. (Voltcraft-MF90-Osc3.jpg)Edit: Pinout of transformer T1 (T1-Pinout.jpg).Hm, that looks like a Hartley oscillator. And NPN type for Q5 is OK.Is the transformer defective?Does anyone have any other approaches or hints before I desolder the transformer and disassemble it if necessary?For the sake of completenesstwo images from the PCB (PCB-LS.jpg and PCB-BS.jpg).Best wishes,shianne(Yes, I can buy such a meter new, but anyone can do that)

author: shianne
author_rank: Contributor
timestamp: December 21, 2022, 05:18:55 pm
content: And here is the follow-up:While measuring the transformer I could not find something unnormal.So I tried another SF245 - it does not work.Tried a SS9014 - voila, oscillations.The measured values seem to be plausible, but I need to check them against another meter. Next year ;-)I am still not sure about the reason for the failure
Voltcraft R-200 or CEM DT-5302 burnt Resistor - Page 1
Forum section: electronics / repair

author: snik
author_rank: Contributor
timestamp: October 01, 2017, 12:51:57 am
content: Get this defective Ohmmeter as "present".Found a burning Resistor in this meter, but can't see the value anymore...Is there an owner of this meter Voltcraft R-200 / CEM DT-5032 who can give me the value / Pictures of my burnt resistor R5 on the main PCB?Thanks

author: retiredcaps
author_rank: Super Contributor
timestamp: October 01, 2017, 02:27:53 am
content: If no one can provide a value, I suggest removing the old one and substituting the same value as R6 for test purposes. If meter works, then you can try and get the real value.

author: Maxelektrix
author_rank: Newbie
timestamp: August 02, 2018, 04:33:32 am
content: Please help. that for the component burned out on my board. give labeling

author: Maxelektrix
author_rank: Newbie
timestamp: August 02, 2018, 04:34:55 am
content: give a photo of the top board. I exploded the chip eight contacts.

author: snik
author_rank: Contributor
timestamp: August 03, 2018, 08:17:30 pm
content: Quote from: Maxelektrix on August 02, 2018, 04:33:32 amI was for my Multimeter in contact with an engenier from CEM, the value of R5 is 15 Ohm.

author: Maxelektrix
author_rank: Newbie
timestamp: September 11, 2018, 05:01:11 pm
content: U4-?

author: serg-el
author_rank: Regular Contributor
timestamp: April 29, 2020, 06:02:12 pm
content: ( U4) 27M2Chttps://www.elektroda.pl/rtvforum/topic3243648.html
Voltcraft VC-890 by UNI-T Firmware - Page 1
Forum section: electronics / repair

author: goaty
author_rank: Regular Contributor
timestamp: June 24, 2020, 02:36:55 pm
content: Anyone got firmware for the EFM32 on a Voltcraft VC-890 made by UNI-T ?Unfortunately the chip is read-protected (I tried reading back using ESP-PROG and OpenOCD).One I/O-pin is dead because the meter is not switching into one mode when turning the knob.Have already replacement MCU, but no software...Unfortunately UNI-T is not responding, and Conrad has no firmware.

author: goaty
author_rank: Regular Contributor
timestamp: July 09, 2020, 01:15:18 pm
content: Unfortunately there is no way getting the firmware, so the meter goes into the bin.I´d really wish we had right to repair by now...