hybridfree/eevblog-posts huggingface dataset:
Resize SSD disk - Page 1
Forum section: electronics / repair

author: GGMM
author_rank: Frequent Contributor
timestamp: February 03, 2025, 09:38:08 am
content: Hello,I would like to know if there is a method to reset the size of an SSD to is origin.I do not explain, I have a 64Gb SSD that I had increased to 4 GB with I believe a Fdisk command.No, there impossible to go back that is to 64Go.I think a software can do this (I tried Erase Us without success) or write in the flash an info?If you have the solution. Thank youcdt

author: Haenk
author_rank: Super Contributor
timestamp: February 03, 2025, 01:53:41 pm
content: If you use Windows, maybe try HD Sentinel and zero out (surface test w/ overwrite) the SSD. That will destroy any partition and should bring back the full cacacity.Similar tools are available for Linux and Mac.

author: coromonadalix
author_rank: Super Contributor
timestamp: February 03, 2025, 04:53:15 pm
content: https://www.partitionwizard.com/free-partition-manager.htmlyou meant decreased to 4gb ? resized to 4gb ?unless you do things completely wrong, you're supposed to be able to revert back to a full original size, if not you have somewhat messed up the controller specs for the partition sizefor your ssd brand you are supposed to get the maker software / tools, normally any good brand is supposed to have somewindows Diskpart should help tooor with any partitioning tool,you have to delete all volumes to get them unallocatedand after you can rebuild the drive to 1 full partition of all the available space

author: voltsandjolts
author_rank: Unknown
timestamp: February 03, 2025, 07:02:46 pm
content: Boot from a linux usb stick and run gparted.See you tube if you want some guidance.

author: fzabkar
author_rank: Super Contributor
timestamp: February 03, 2025, 07:44:18 pm
content: With respect, it's unclear what has happened.Can you show us the SMART report?https://crystalmark.info/en/software/crystaldiskinfo/Can you show us the Partitions tab in DMDE?https://dmde.com/
resizing polishing buff to restore hard BNC plating? - Page 1
Forum section: electronics / repair

author: coppercone2
author_rank: Super Contributor
timestamp: May 14, 2021, 06:00:33 pm
content: So I figured out that for silver plated BNC, the best way is to desolder them, ultrasonic clean for a long time and then give a dip in tarn-x, it makes them look decent again. Not polished but shiny and clean and likely very accepting of oil, and basically there is no mechanical work done on it.However, for the chrome? BNC connectors, I am at a bit of a loss. I saw a post by Robrenz where he used a chrome polish on a hollowed out buff that goes into the BNC port while attached to a rotary tool to do the inner surface.Just how the hell do I resize or cut a piece of wool? Are there any other methods for this?I found that using a small buff with chrome polish from the hardware store makes the outside of the connectors look good again, but I have no way to do the inside of the tube, especially with a 75 ohm pin and dielectric blocking the middle.Do you need to cut these things on a lathe? Is there another method? Unlike silver, I don't think that the ultrasonic will touch the kind of corrosion formed on the chromed BNC connectors, so I don't think my silver plated BNC method is an option, plus since its hard chrome (or is it nickel?), when you use the buff it actually gets nice and reflective again, instead of super silver mate color like the cleaned silver BNC connectors (I don't want to mess with abrasives and thin silver plating anyway since it looks good, someone saw it and said 'thats silver', so I know I did a good job ).I thought to maybe to try to drill the middle out but for some reason I don't see anything working on a wool pad, and even if that did work, how do you resize the outside diameter?I am only working with signals to like <1MHz, so its not going to be a signals issue. Some of them are really dirty with 'spots' of corrosion, not just discoloration, that do go away with slightly heavy polishing action using the chrome polish, so I think I need to use a tool for this.This is the best method I have seenThis is the secret to the super clean BNC insides. I mount a very hard felt cylinder in a Dremel tool running at 5000 rpm. In "manual lathe mode" take an exacto knife and bore a hole in the felt that clears the teflon insulator of the BNC. Also turn down the outside diameter of the felt to be a snug fit into the BNC. This can be a very dangerous thing,apply all your wood turning skills here. Soft felt won't work, it will fly apart before you get the shape you need.-robrenzI want to know, is there a easier way.The best method I have so far is to use a Q tip and swirl it around inside up to the dielectric pin, then use a micro expensive q-tip from caig to swirl between the dielectric and the inner body, its very slow and wasteful but I foresee a grievous injury from trying to shape a spinning felt with a exacto blade. Looks like more then a few hours of tedious work to do it by hand but I want something that will not result in injury.
Resource for finding cap lists for TV's? Sony KD-70X690E Part #1-897-216-11 - Page 1
Forum section: electronics / repair

author: phuzzyday
author_rank: Newbie
timestamp: March 08, 2025, 10:08:21 am
content: The title says most of it! It's the power supply that I'm going to recap. It's just started rebooting randomly.Call it a first shot at a problem, seeing as it's got a LOT of hours on it and not a huge number of caps anyhow. Plus they are cheap, even top end ones! I guess I'll have to pull the back off anyway... It's just that last time a TV did this to me I found a guy selling cap kits! That would be even better.Thanks in advance. You guys are the heroes!PD
restore Rigol DS1052D - Page 1
Forum section: electronics / repair

author: shurikstepanenko
author_rank: Newbie
timestamp: December 10, 2021, 04:15:08 am
content: Hello. I really need help to restore Rigol DS1052D.Broke my device with the wrong firmware.I am looking for firmware (dump.bin) for Rigol DS1052D or Rigol DS1102D.Perhaps someone downloaded from the device.Today I managed to find the firmware for Rigol DS1052Е version 00.02.04 SP1, which I uploaded to the device and it started, but I cannot downgrade to 00.02.02 SP2 and try to rename the serial number to my own.If anyone can help I will be very glad. Thank you.

author: shurikstepanenko
author_rank: Newbie
timestamp: December 15, 2021, 06:03:16 am
content: Maybe someone has a patched firmware to downgrade version 00.04.02.01.00 to Rigol ds1052e
Restoreing simpson 311 vtvm - Page 1
Forum section: electronics / repair

author: Jeff L
author_rank: Contributor
timestamp: November 18, 2023, 07:30:40 am
content: Need help finding R11 (300 kohm) on Simpson 311 vtvm --looked all over?Never mind --found it. Still having trouble reading 500 VAC and 1500 VAC. Looks like a charging capacitor?
Restoring a 7 segment LCD display with bleeding issues? - Page 1
Forum section: electronics / repair

author: srd
author_rank: Newbie
timestamp: August 04, 2022, 04:17:00 pm
content: Hi,I've recently aquired a device with a 7 segment LCD display that suffers from a bit of bleed (see attached photo, though it doesn't look as bad in real life). Now if it were just a normal numerical LCD display, I'd replace it with a new one. However this display has bespoke segments for units and over-/underrange indicators. Is there any way to restore the display? I've searched a bit on google, but beyond "apply pressure and hope for the best" I haven't found any pertinent information.I'm currently a bit hesitant to go experimenting, since the display is made of several layers of glass, and the last thing I want to to break the display by some avoidable accident. Like cracking it due to heat stress when desoldering...Any advice is appreciated!

author: wraper
author_rank: Unknown
timestamp: August 04, 2022, 04:20:23 pm
content: No, it's dead and cannot be fixed.

author: srd
author_rank: Newbie
timestamp: August 04, 2022, 07:11:00 pm
content: Ah, thats too bad, but thanks for the information.

author: PaulAm
author_rank: Frequent Contributor
timestamp: August 07, 2022, 02:12:25 am
content: What some people have done in that situation is swap in an OLED matrix display. Of course you need to know how the current display is driven and then translate that to a dot matrix display and build the hardware to do it.Didn't say it was easy

author: wraper
author_rank: Unknown
timestamp: August 07, 2022, 09:06:56 am
content: You can design and order a custom LCD.https://hackaday.com/2018/07/24/custom-lcd-module-is-unexpectedly-cheap-and-easy/

author: srd
author_rank: Newbie
timestamp: August 16, 2022, 06:38:20 pm
content: PaulAm: This piece of equipment is so old that the manual doesn't only contain the circuit layout, but it goes through every part of it piece by piece in detail and how it works. I had already considered adding a microcontroller based translator for a modern display. I haven't really done much digital electronics yet, but noone said that this needs to be done tomorrow.wraper: That is very interesting, thanks. I would have thought that custom LCD displays would be a lot more expensive. Not sure if this piece of equipment would warrent spending that much for a new display, but its a life line if all else fails! Thanks again.
Restoring an old 1968 hp 200AB audio odìscillator - Page 1
Forum section: electronics / repair

author: walter.brollo
author_rank: Newbie
timestamp: February 22, 2023, 06:38:03 am
content: Hi, here:you can find an interesting video on restoring a 1968 hp 200AB audio odìscillator

author: jonpaul
author_rank: Super Contributor
timestamp: February 23, 2023, 03:45:04 am
content: see Linear Technology the late and great Jim Williams long papers and notes,on exactly the theory, invention and restoration of Hewlett Packard's 1936 Pioneering 200 audiovisuelle oscillatorjon
Restoring NiMH batteries - Page 1
Forum section: electronics / repair

author: SilverSolder
author_rank: Super Contributor
timestamp: December 07, 2020, 09:55:24 pm
content: I have a batch of power tool batteries, NiMH 3800mAh types, that have been left discharged for a long time...Any experience/suggestions on how to recover them back to a serviceable state - or is it completely hopeless?

author: helius
author_rank: Super Contributor
timestamp: December 07, 2020, 10:17:52 pm
content: The IEC 61951-2 3.0 contains a procedure, section 7, which is the industry standard procedure for capacity testing single cells. It can also be used to recover capacity in deeply discharged cells like yours."A constant-current charge at 0.1C for exactly 16 hours including a 6 hour overcharge, afterwards stored for 4 hours, then discharged for at least 5 hours at 0.2C down to a 1.0V cut-off." You repeat the procedure up to 5 times until the rated capacity (measured during discharge) is reached.

author: tunk
author_rank: Super Contributor
timestamp: December 07, 2020, 10:21:37 pm
content: What's the nominal and measured voltages of the battery?And you may want to open it and measure the individual cells.

author: RoGeorge
author_rank: Super Contributor
timestamp: December 07, 2020, 10:21:37 pm
content: Just charge them, and see if any of the packs are still usable.If not, don't bother trying various cell recovery recipes found online. They never work. I've tried.At most you can dismantle the packs and test each element individually. Usually only 10-20% of the elements are bad inside a pack, the rest of the elements are still usable. Replace only the most bad ones and thus you may end with a working battery pack. This is usually very time consuming, ideally requires a spot welder, and there is no guarantee the resulting pack will last for long. Expect the other cells to fail, too, sooner or later.

author: SilverSolder
author_rank: Super Contributor
timestamp: December 08, 2020, 06:56:17 pm
content: Thanks for the suggestions. I have opened the pack, separated the cells out, and am now using an external charger to try to refresh the cells one at a time.Will report back on the results, this could take a while!

author: Labrat101
author_rank: Unknown
timestamp: December 08, 2020, 09:23:39 pm
content: Quote from: SilverSolder on December 08, 2020, 06:56:17 pmI have also tried this process does not work that well 50/50 chance.There is another way that does work and that is pulse charging . I used 10,000uf capacitor and pulsedat 30 second intervals until the battery voltage starts to rise . then increase the pulse slowly.If the voltage DOES not increase after about 5 minuets the battery should be classed as RIP .And these batteries even if they do recover will Die again after a short time.AS RoGeorge said its better to replace all the batteries (cells) with new .it will be well worth it in the end .
Restoring photos from broken Nokia Asha 300 - Page 1
Forum section: electronics / repair

author: dtm_
author_rank: Newbie
timestamp: August 18, 2024, 05:46:11 pm
content: Hi.I have old broken phone Nokia Asha 300:https://www.gsmarena.com/nokia_asha_300-4279.phpIt does not start - when I press the power button (the red one) nothing happens. Charging it using an USB cable plugged into a laptop also does not work. However, my goal is not to turn on this phone, but to somehow restore photos written on its hard drive. I disassembled it to get access to the motherboard, but I cannot figure out where the internal memory is located and how to get access to it. I send pictures of the motherboard as attachments:1) my original photo2) the photo with names of the elements I was able to recognizeMy questions are:1. Where can I find the internal memory on that motherboard?2. Is there any way to get access to data stored on it externally, without starting the phone?I am a kind of noob in this topics, so any help will be appreciated.

author: fzabkar
author_rank: Super Contributor
timestamp: August 19, 2024, 10:59:57 pm
content: Service manual:https://elektrotanya.com/nokia_asha_300_service_manual_l1_l2_v1.0.pdf/download.htmlThe memory appears to be the K5 IC on page 20.

author: wraper
author_rank: Unknown
timestamp: August 19, 2024, 11:07:09 pm
content: Note this phone won't turn on without working and at least a little bit charged battery even with charger attached. So first thing you should do is to check if there is actually voltage on its terminals. As of reading the data without making the phone to turn on, forget about it.

author: wraper
author_rank: Unknown
timestamp: August 19, 2024, 11:20:10 pm
content: Also I'm not 100% surebut its micro USB port is likely for data only and cannot be used for charging similar to other Nokia phones from that time.

author: Postal2
author_rank: Frequent Contributor
timestamp: August 20, 2024, 03:36:27 am
content: Connect the battery and charge it by connecting the adapter according to the picture (the minus is connected to the ground, check it).

author: dtm_
author_rank: Newbie
timestamp: August 21, 2024, 06:48:04 pm
content: Quote from: wraper on August 19, 2024, 11:20:10 pmAccording to this manual:https://files.customersaas.com/files/Manual/Nokia_Asha_300_User_manual.pdfit should be possible, I don't have any other information.Anyway thanks to you guys for your insights. It will be tricky thing, but I will try.

author: fzabkar
author_rank: Super Contributor
timestamp: August 21, 2024, 07:02:56 pm
content: Quote from: dtm_ on August 21, 2024, 06:48:04 pmI found the same thing.Specs:https://www.phonearena.com/phones/Nokia-Asha-300_id6511FCC filings for FCC ID PPIRM-781:https://fccid.io/PPIRM-781User manual:https://fccid.io/PPIRM-781/User-Manual/Manual-1558595.pdfThe manual also states that the Nokia 300 (is it the same phone?) can transfer data over USB and Bluetooth.
restoring RCA Voltohmyst Senior need part source - Page 1
Forum section: electronics / repair

author: Jeff L
author_rank: Contributor
timestamp: November 21, 2023, 08:49:46 am
content: I'm restoring a RCA Voltohmyst and came across a 4 section potentiometer , 10K, 1/4 Watt, p/number 221336. Somebody overamped one section,and now the plastic adjuster won't move. Any possible source?

author: alm
author_rank: Super Contributor
timestamp: November 22, 2023, 12:18:32 pm
content: Given that not everyone may be familiair with this particular instrument, maybe posting clear pictures of the part might help find a replacement if it's not a custom part.

author: Synthtech
author_rank: Regular Contributor
timestamp: November 22, 2023, 12:35:20 pm
content: I’ve been restoring a Voltohmyst along with several other VTVM’s and tube testers and a couple of vintage but solid state multimeters. My advice with any equipment repair or restoration of devices with a moving coil meter that is decades old is to first, before anything else to test the meter movement itself to see if it can still reach full-scale-deflection at the stated FSD current.It’s not that uncommon for some old meter movements to lose field strength in their permanent magnet and in some test gear this makes it unable to be calibrated as the meter just can’t deflect enough. Be very careful though never to try and test a meter movement with a multimeter ohms range, many movements have FSD current in the uA range so you need a power supply and a decade resistance box and a precision resistor to measure current drop and a good multimeter to measure that drop and to calculate the meter coil resistance. Putting a multimeter on ohms range directly across the meter will damage it as the multimeter test voltage is too high.

author: Stray Electron
author_rank: Super Contributor
timestamp: November 22, 2023, 02:17:29 pm
content: Quote from: Synthtech on November 22, 2023, 12:35:20 pmX2. And I'll add that the meter movement in many of the High Grade meters is quite delicate and they frequently don't survive being shipped. Ask me how I know!

author: GLouie
author_rank: Regular Contributor
timestamp: November 22, 2023, 03:57:31 pm
content: I have a 1955 original manual for the RCA Senior Voltohmyst here and don't see that part listed. There may have been design changes, so yes, photos, dates, serial number may help.

author: Jeff L
author_rank: Contributor
timestamp: November 24, 2023, 02:35:39 am
content: Decided to go with brand new, sealed 18 turn potentiometers from Digikey-- next day delivered-- CND$3.75 ea.
Restoring the case of a Fuke 99 - Page 1
Forum section: electronics / repair

author: lastwarrior
author_rank: Contributor
timestamp: April 16, 2020, 03:26:23 pm
content: Hello everyone, recently I got a fluke 99 scopemeter with a damaged LCD cover (transparent plastic).Because the electronic part is functioning properly after changing some caps and the memory battery, the quation left is about this plastic window.If there is anyone who knows what kind of plastic it is made off, would be great.In my opinion, it looks like a plexiglass.Thx in advance.

author: lastwarrior
author_rank: Contributor
timestamp: April 17, 2020, 08:34:31 am
content: There sould be a way to change it (except buying same scopemeter or entire front cover). Maybe someone have done similar job in the past. Will appreciate any hint.
Resurrecting an Agilent E5500 phase noise test system - Page 1
Forum section: electronics / repair

author: cosmo little
author_rank: Contributor
timestamp: October 14, 2025, 12:41:51 pm
content: I am trying to resurrect an E5500A test system which last worked more than 10 years ago. This comprised an HP 70420A test set, an ISA GPIB card, and an HP 89410A signal analyser. The GPIB card is of no use, so I have ordered a USB to GPIB convertor.The computer used ran Windows 32bit XP. Unfortunately all my 32bit computers are long since scrapped. I still have a computer running 64bit Windows 7, and two possible computers running 64bit Windows 10.Keysight still offer downloads of the E5500 software, this comes in 2 parts, E5500-prerequisites ( > 3Gbyte) , and E5500-installer, both are exe files.The E5500-installer installs the viewer and main menu, however essential features such as the asset manager call a file which does not exist.These files are presumably part of the prerequisites.The latest version appears to be a Windows 10 upgrade to a previously installed Windows 7 version, which can also be downloaded.So far. I have succeeded in installing the viewer on both Windows 10 and Windows 7 computers, however installation of the prerequisites always failsBefore I get into details as to why the installation fails, has any reader succeeded in making a new installation of this software?

author: Phaseseeker
author_rank: Regular Contributor
timestamp: October 14, 2025, 01:03:16 pm
content: Keysight's website explicitly specifies "32-bit Windows 7", so have you tried using it with a 32 bit install of Windows? You can install a 32-bit copy of Windows on a 64-bit computer with no issues.

author: CrazyTiger
author_rank: Regular Contributor
timestamp: October 14, 2025, 01:07:58 pm
content: Why not use a virtual machine with 32bit operating system?Its very easy to setup and USB to GPIB adapters works on virtual machine perfectly.
Retro Electro Workshop - new UKTV programme - Page 1
Forum section: electronics / repair

author: 807
author_rank: Frequent Contributor
timestamp: July 13, 2023, 11:37:30 pm
content: Starting next Tuesday 18th July at 9pm in the UK on "Yesterday" channel, is a new 10 part series called "Retro Electro Workshop"...UKTV's factual channel Yesterday has commissioned a new UKTV original series, Retro Electro Workshop (10X60'), a new and informative documentary series about the dying art of repairing electronics, fronted by super-fixer Rob Howard, one of the UK's last remaining full-time repair men of retro-electronic products.The first episode features a 1980's Atari (doesn't say which model).https://corporate.uktv.co.uk/news/article/yesterday-commissions-retro-electro-workshop/
Retrofitting the step attenuator to my 8711C(8712C) - Page 1
Forum section: electronics / repair

author: wieserfalke
author_rank: Newbie
timestamp: July 26, 2025, 09:31:02 am
content: Hi,I wanted to as if there are some that could make me some pictures of their step attenuator Option in their 8711C/8712C since I would love to retrofit it in to mine, if one even reverse engineers the PCB it would be ideal since this is easier when having the PCB.Of what I am able to find out, it should be possible since the actual step attenuator can be bought on eBay for not that much and the PCB does not seam to be that complicated.Lastly, it could also be helpful if someone with a 8713C/14C would make some pictures of their step attenuator Option to see if they are the sameFor reference, here is a picture of my current A5 module:" alt="" class="bbc_img" />

author: wieserfalke
author_rank: Newbie
timestamp: August 04, 2025, 11:01:45 am
content: Ok, what I found out for now,It should be posible t use the Attenuator and PC from the E and ET variants. those are 33321-60044 and 08714-60170 A3824. The only modification one most likly should make is to remove the LM393, to prevent any problems.Attached some Pictures of the PCB.HP->IC17->319->21->23->25->7

author: wieserfalke
author_rank: Newbie
timestamp: August 04, 2025, 12:27:35 pm
content: It seams to work, I still need to do more tests but some siple first test worked.One thinkg that one needs to keep in mind is, that the PCB of the ES/ET variants is bigger.
Reusing damaged 10S 5P battery pack TechSum TP-BA150H - Page 1
Forum section: electronics / repair

author: univ
author_rank: Contributor
timestamp: September 07, 2021, 05:23:49 pm
content: Dear forists,I couldn't walk by this slightly damaged battery pack which I'd like to reuse, preferrably complete with its battery management system.I couldn't find any info on the exact pack or its BMS, and there's some repair needed, so I need some advice.The pack has been smashed into something, resulting in some severed cables (to the battery level indicator and charging port) and one crushed IMR Li-ion cell. The main connector is still intact but did not show any voltage above 1V. The whole battery still reads at 37V (10S 5P @3.7V).I took it apart and shot some photos:At the moment these are my questions:Could somebody point me to any datasheet or description of a similar battery pack or BMS that I could use?How might the connectionsA BandIDbe used, are they essential to use the board?I'd replace the crushed cell with a cell of the same type (INR18650MH1). Probably not a big deal, would you object?In lieu of a matching charger, what could be the most prudent option for charging such a pack? Just stick 42V to it? Might it work with a lower voltage, say a 19V laptop brick?Here's hoping to read you soon, thanks for your advice and your time!Best regardsChris

author: tahc81
author_rank: Newbie
timestamp: September 01, 2022, 12:34:41 pm
content: Hi, I have similar one. Please note there's a MCU and you have to find, which pin controls the mosfets. I'll check later... Charging should work without issues, please check.

author: tahc81
author_rank: Newbie
timestamp: October 05, 2022, 01:08:57 pm
content: Hi, U3 should be BQ76200 or something similar. There's pin DSG_EN (DiScharGe ENable), and connecting 3.3V to this pin logically enabled voltage on a output terminals - just checked on my pack.

author: ANTOINE
author_rank: Newbie
timestamp: February 16, 2025, 12:09:25 pm
content: So, I'm wondering if you need to power pin 6 DSG_EN to discharge the battery, means you need to remove the 3 V from pin 6 and power pin 4 CHG_En to power back the battery?
Reverse engineer and repair a generator AVR - Page 1
Forum section: electronics / repair

author: Alex_Baker
author_rank: Frequent Contributor
timestamp: July 23, 2024, 07:24:52 pm
content: Howdy peopleI have a "vintage" Honda EM500A portable generator from the early 80s in need of repair. When I first got it it had carburetor issues, but now that I have that sorted out I discovered that it was outputting low voltage, around 90v or so.I was able to acquire a service manual and check that all the windings in the unit matched the resistance specs, so my focus went to the little AVR unit. Unfortunately there is no schematic available, or replacement parts. There are virtually no replacement parts available for this generator as a whole. The AVR was also completely sealed in resin. Once I decided to take the leap and disassemble the AVR, I let it sit in paint stripper for over a week to remove the resin. This process nearly destroyed the electronics, but there is just enough left that I think I can repair it with this forums help.I have attached the schematic that I came up with, as well as the generator's wiring diagram. Does this schematic make sense? I also need help figuring out what the component labeled TH is, it disintegrated in the solvent, but it seemed to be filled with black grit, which made me think that it was a varistor.

author: fzabkar
author_rank: Super Contributor
timestamp: July 23, 2024, 08:38:28 pm
content: That looks like a typical automotive regulator, apart from the AC windings. I don't know how important the thermistor is, though. ISTM that the positive tempco of the zener could be chosen to offset the -2mV/C tempco of the diodes and the transistor B-E junction.

author: MarkF
author_rank: Super Contributor
timestamp: July 24, 2024, 03:08:56 am
content: Here is a video for a EM500 with a lot of good info.Unfortunately, I think you're looking at a new AVR.https://www.youtube.com/watch?app=desktop&v=feRasa6NCi0Watch to the very end for a view of the de-potted AVR.He says there is NO info or circuit diagram for your AVR available.

author: Alex_Baker
author_rank: Frequent Contributor
timestamp: July 25, 2024, 03:07:57 pm
content: I spent some time and rebuilt the AVR using the values I had in the schematic and a 10k potentiometer in place of the component labeled TH. I used new capacitors and resistors but kept the transistors and rectifiers.To my surprise it actually worked! I was able to get the voltage up and could tune it with that potentiometer. No load to full load the voltage sags a bit more than I would like, about 10 volts, but I wont worry about that too much for now.

author: coromonadalix
author_rank: Super Contributor
timestamp: July 25, 2024, 03:17:32 pm
content: yepyou have to depot it and try to figure out many things, but if the chips or transistors are nit buffered out, things are possible ?AVR teardown

author: fzabkar
author_rank: Super Contributor
timestamp: July 25, 2024, 03:21:38 pm
content: What did you use for TR1? A value of 13K for R0 would require a very high hfe in order to get an appreciable field current (1A ?). Is TR1 a Darlington pair?
Reverse polarity  - Page 1
Forum section: electronics / repair

author: Erwin Ried
author_rank: Regular Contributor
timestamp: August 14, 2024, 09:21:14 am
content: Hi! by mistake a negative-center 12V plug was connected to this archer tp-link mr600(EU) 4g router, this is the damage:I imagine there was a fuse and some regulator? by any chance anyone has a hint how to make it work again? there is - + 12V to the right side of the switch button (the bigger pads, T13 is positive)

author: squadchannel
author_rank: Frequent Contributor
timestamp: August 14, 2024, 09:40:52 am
content: When a regulator is damaged, most of the time the input voltage is output on the output side.You would first try applying voltage to the output side of the regulator. If it works fine, then I would replace to common regulator such as the 780x.The voltage can be guessed by examining the datasheet of the chip or other device that is supplying the voltage.

author: Erwin Ried
author_rank: Regular Contributor
timestamp: August 14, 2024, 10:44:51 am
content: you think those fbxx components where regulators? I was gonna to do something like that but I think they are so small, because the whole router has heatsinks and such, so I wonder how could that small regulator be the only one.Could it be a step down 12->5V for example to be later turn into 3 o 1.8V ? it is weird that just by the power input there is not inductors either, those are very far away with some "power-handling-looking" circuitry

author: squadchannel
author_rank: Frequent Contributor
timestamp: August 14, 2024, 10:54:29 am
content: FB is probably a ferrite bead.want to make it work for now, supply power to C348, 349, and 350, taking care of the polarity. advisable to test while limiting the current.I wondered had a regulator, but there doesn't seem to be one. Perhaps there is a regulator elsewhere not shown in the image.

author: Erwin Ried
author_rank: Regular Contributor
timestamp: August 14, 2024, 12:10:05 pm
content: Nothing on the top that looks like regulator:But on the bottom:This 2 looks like:I will try what you say, maybe powering with low voltage initially
[SOLVED]Revox B261-LCD segment fault finding. - Page 1
Forum section: electronics / repair

author: djsb
author_rank: Super Contributor
timestamp: October 14, 2021, 02:52:26 pm
content: Hi,The lower segments of the second digit (the first zero in 100 from the left) do not appear. I have attached the schematic below. I'm trying to identify which pins to apply voltage to (using my multimeter on the resistance range) in order to turn on these segments. The numbering on the pins is a bit confusing, as each pin appears to relate to more than one segment. Is there a recommended way of testing segments on this LCD without powering up the whole circuit, as I have removed the PCB from the tuner temporarily. I have watched Dave's LCD video's, and he mentions that applying a DC voltage is not the best thing to do. Any advice welcome. Thanks.Revox_B261_LCD.pdf(635.36 kB - downloaded 80 times.)

author: Alex Wolf
author_rank: Regular Contributor
timestamp: October 14, 2021, 03:15:31 pm
content: Quote from: djsb on October 14, 2021, 02:52:26 pmBetween Com I or Com II and the segments you want to test.

author: Runco990
author_rank: Frequent Contributor
timestamp: October 14, 2021, 06:15:31 pm
content: It is very common with Revox gear that the LCD has bad connections between the glass and the contact strips that hold it. A little squeeze and wiggle will usually show this. Did you try this before delving into electrical troubleshooting? Always try that first.

author: djsb
author_rank: Super Contributor
timestamp: October 17, 2021, 02:03:38 pm
content: I've moved the contacts on the edge of the glass and now the segments are working again. Thanks.

author: Runco990
author_rank: Frequent Contributor
timestamp: October 17, 2021, 11:34:51 pm
content: You're welcome!
REVOX B780 does not retain tuner preset memory when unplugged - Page 1
Forum section: electronics / repair

author: Boogeydog
author_rank: Newbie
timestamp: November 20, 2023, 04:44:39 pm
content: Good Day All,Hoping for some great guidance. I recently rebuilt a Revox B780 that was for the most part still working except for two issues. One was one phono channel was dead, the other tuner memory was not being retained when unplugged. Replaced the electrolytics, cleaned IC sockets and all connectors, replaced some badly corroded IC's yada yada. Got everything working pretty good but no luck with memory issue. I did have to clean the battery compartment and connecting wires. Checked that there is proper voltage leaving the battery pack. Checked that a charge voltage was present for the battery pack. My suspicion, being that I had badly corroded IC's, the one responsible for retaining memory requirers attention. Tracing to this extent is beyond my capability however. I would like to get it working 100% as it is a wonder of design. Any suggestions would be greatly appreciated!Many thanks!

author: wasedadoc
author_rank: Super Contributor
timestamp: November 21, 2023, 11:23:54 am
content: What are the battery voltages when the tuner is plugged into AC and when it is not?

author: GLouie
author_rank: Regular Contributor
timestamp: November 22, 2023, 04:07:44 pm
content: I don't know this unit, but a quick scan of the service manual from HiFi Engine indicates you need to check for battery pack voltage at pin 4 of the microcomputer chip IC1, which looks like memory backup.

author: Boogeydog
author_rank: Newbie
timestamp: November 23, 2023, 07:22:37 pm
content: Somewhere around 5.6 both ways.

author: Boogeydog
author_rank: Newbie
timestamp: November 23, 2023, 07:25:45 pm
content: Thanks for that. It is looking like trouble with the microprocessor. I think I am boned.

author: wasedadoc
author_rank: Super Contributor
timestamp: November 24, 2023, 03:05:05 am
content: How long between removing power and measuring the voltage? How long does the power interruption need to be for memory to be lost?
Revox B780 no output volume - Page 1
Forum section: electronics / repair

author: Lowbuyer
author_rank: Newbie
timestamp: September 19, 2020, 03:27:02 pm
content: Hi I have a Revox B780 which was working fine and one day while it was playing music from TAPE1 line input the volume stopped from both channels.Has anyone seen this before? any idea where to look first?

author: BU508A
author_rank: Super Contributor
timestamp: September 29, 2020, 08:41:00 am
content: You should post this in the repair section here:https://www.eevblog.com/forum/repair/Chances are much higher then, that somebody will help you.I'd recommend to ask one of the mods to move this thread there.Edit:Thanks Simon.

author: Lowbuyer
author_rank: Newbie
timestamp: October 01, 2020, 06:57:45 pm
content: I fixed the problem, 1n4448 zener diode and BC337 gone that drive the relay.
Rewiring An Astatic G Stand With A 3 Pin Connector - Page 1
Forum section: electronics / repair

author: Ookpik
author_rank: Contributor
timestamp: August 16, 2023, 01:08:59 am
content: I have an 3 pin Astatic G stand that I wish to add a 3 pin female connector to the end of the cord.The cord has two white wire conductors with shield.Which wires do I solder to pins 1 - 2 - 3 on the connector shown?White wire with orange terminal dot to pin number ?White plain wire to pin number ?Shield wire to pin number ?Any help in this matter would be greatly appreciated!Please see the photo below for additional info.

author: DimitriP
author_rank: Super Contributor
timestamp: August 16, 2023, 01:48:26 am
content: astaticBelow is a G-Stand diagramIt doesn't show the other end of the connector whihch is what you are looking for and it shows a red and white whire as well as a shield.What-goes-where depends on what the radio expects.

author: Ookpik
author_rank: Contributor
timestamp: August 16, 2023, 04:10:05 am
content: Thanks for the response!I also found that schematic but like you stated, it does not include the information I am seeking.
Rewiring old equipment... - Page 1
Forum section: electronics / repair

author: nctnico
author_rank: Super Contributor
timestamp: July 10, 2020, 10:39:01 pm
content: Not really test equipment related but wanted to share anyway. Several decades ago I got an old compressor and the last few years the mains wiring started to look a bit shoddy so I decided to rewire it. The mains wiring isn't complicated. It goes through an automatic-shut off switch to a single phase motor. The motor has a Klixon to switch the starter winding off once the motor runs and the usual running capacitor. The motor might be over 50 years old. When opening the wiring housing I noticed that the wires for the running capacitor didn't look very good. Once I got the running capacitor removed the insulatation just fell off:I should have rewired this thing ages ago. To determine a replacement capacitor I measured the value; still at 54uf which is about right for a 250W motor.
Rework BGA Processor with Solder Paste or Solder Balls? - Page 1
Forum section: electronics / repair

author: 2X
author_rank: Frequent Contributor
timestamp: June 06, 2024, 07:21:04 pm
content: Hello, I want to ask if it is better to solder a big BGA chip/processor (big compared with the BGA chips with pins ~20pins that I use to rework with paste) with solder paste or with solder balls? I read on the below thread that balls make a better alignment of the chip. What is your opinions? Also do you have to suggest me any thermal profile for a chip like this (unfortunately I can't find any datasheet of this chip to look for a thermal profile from his manufacturer). For a hot Air I have the below.https://www.eevblog.com/forum/beginners/bga-reballing-maybe-a-dumb-question-but/https://www.jbctools.com/jtse-power-hot-air-station-product-1261.html

author: Harry_22
author_rank: Frequent Contributor
timestamp: June 07, 2024, 07:20:17 pm
content: Hi!Rolling balls is a very simple procedure that improves fine motor skills. It will take half an hour to make such a chip without skills.The most important thing is to apply a thin and very even layer of flux otherwise the balls will stick together during melting.But you will need a microscope.

author: daisizhou
author_rank: Super Contributor
timestamp: June 08, 2024, 02:05:20 am
content: You need a steel mesh as shown below to easily complete the work.About working curve --Usually the BGA workstation has a default curve, you can select the default one. If you choose lead-free solder balls, then select the corresponding curve, which is done automatically.

author: 2X
author_rank: Frequent Contributor
timestamp: June 08, 2024, 03:58:07 pm
content: Thanks for your reply. For your opinion us I understand the balls are better from paste?Also, because I have never use balls; the appropriate size/diameter of the balls for each stencil is for example at your image the 0,6mm that writes on it?

author: daisizhou
author_rank: Super Contributor
timestamp: June 08, 2024, 08:52:01 pm
content: Quote from: 2X on June 08, 2024, 03:58:07 pmNO Usually the paste is suitable for small BGA chips。For example, the type of mobile phone MCU。If paste is used for large BGA, it is easy for the paste to leak out during actual operation, resulting in failure.And it is difficult to ensure consistency0.6mm is the specification (diameter) of the solder ball
rf fet buffer output "bandaid" amp or txf - Page 1
Forum section: electronics / repair

author: sae-7125
author_rank: Newbie
timestamp: October 22, 2022, 06:18:30 pm
content: due to an eternal grade gremlin inside a gorler tuner gang, that shall live in infamy, i need to figure out a signal booster.either a simple circuit utilizing the 5v supply, i have some bc547 npn in stock, or a step up transformer that can handle 70-110 mega hertz bandwidth. there is approximately 200mv pk-pk of rf from the fet buffer and at most i would need 1.5v rms rf to feed the next headache (posted in another thread).i wonder if something like this would work, only with bc547 through-hole instead of bfp740 smt??http://howtodosteps.blogspot.com/2017/10/lna-wideband-100-mhz-to-4-ghz-rf.htmli seem to be spending too much time on mouser trying to drill down component specifications and alternatives.
RF Si transistor identification - Page 1
Forum section: electronics / repair

author: alan.bain
author_rank: Regular Contributor
timestamp: September 08, 2024, 12:12:27 pm
content: I'm trying to identify the active device in a 3.6GHz DRO oscillator found in an E444X series Spectrum analyser. There is even a write up of a very similar oscillator design in Microwave Journalhttps://www.microwavejournal.com/articles/11889-high-tuning-sensitivity-dielectric-resonator-oscillator-from-optimization-of-dielectric-resonator-te-sub-01-948-sub-modewhich sadly doesn't say what the device is. It is marked 420 with a dot see photo to the left of the dielectric ring.

author: RoGeorge
author_rank: Super Contributor
timestamp: September 08, 2024, 03:29:14 pm
content: Could it be BFP420, or equivalent?

author: alan.bain
author_rank: Regular Contributor
timestamp: September 09, 2024, 10:20:54 am
content: Thanksl that was a useful starting point. I don't think it is right, but it led me to the Avago AT-42086 which has a specification which looks like it might work and some pictures of them (on eBay!) show the marking of 420.

author: fzabkar
author_rank: Super Contributor
timestamp: September 10, 2024, 09:44:41 pm
content: AT-42085 has the same marking:https://www3.nd.edu/~hscdlab/pages/courses/microwaves/labs/AT42085.pdfhttps://ja.aliexpress.com/w/wholesale-AT%2525252d42085.html(photos)
"DELAMINATED"  RFI Display - optical shield - Page 1
Forum section: electronics / repair

author: bozidarms
author_rank: Regular Contributor
timestamp: December 23, 2020, 09:04:00 am
content: Hi to the community,does anyone know if repair possible is, the shield is somehow delaminated?It is one HP/Agilent/KeysightRFI Display - optical shieldfor 45670 Analyzer.Thanks in advance
RFQ - Repair Rohde & Schwarz FSP30 9 kHz to 30 GHz Spectrum Analyzer - Page 1
Forum section: electronics / repair

author: thehater
author_rank: Contributor
timestamp: January 28, 2025, 05:19:35 pm
content: I am looking for a person to help repair/troubleshoot my Rohde & Schwarz FSP30 9 kHz to 30 GHz Spectrum Analyzer. Unit is not passing self calibration and returning an error. I have uploaded an image of the failure. I'd prefer an individual in the Northeast of America but I will work with qualified/experience individuals.I appreciate your help send and message my way. Thank you!

author: mr ed
author_rank: Regular Contributor
timestamp: January 29, 2025, 01:52:37 pm
content: Free advice warning. Looks like one RBW filters has drifted out of spec or its pin diodes controlling the filters has gone bad. R+S can be a tough board fix. Most adjustments and hw parameters are on boards in flash or on the motherboard needing secret external firmware to reset. With a service manual try to figure which card is causing the issue and just swap cards. I had 3 broken R&S Smiq gens, I got 1 ot of 3 to cal 100% Ok after a lot of work. One is OK but not perfectly flat output, one is now for parts. Swapping cards was by far faster and cheaper. The manuals all suck too. There are individul parts that are 2 or 300 dollars each in the gens. Your SA may be similar as they date the same. Your SA is worth a lot more than a gen however. Go the board swap route.

author: CrazyTiger
author_rank: Regular Contributor
timestamp: January 30, 2025, 05:00:25 am
content: What is the result of Self Test?Can you provide a picture of the FSP30 noise floor in a preset condition, with nothing connected.Also run the the cal total in service mode, use the password "894129" to run the cal total. This will run the complete cal total and self test, without stopping midway when it encounters failure.My guess this is likely being cause by the frontend module or IF Filter Module. Frontend module is a sandwich of Frontend 1 and Frontend 2 module.Its likely not microwave module. But you can eliminate the module by removing the microwave module, and performing a cold boot. (pressing dot button when turning on) this will make the instrument read all the modules again from eeprom. When the unit does not detect microwave module, it will configure itself as FSP3. After that run the cal-total and self test again. If the unit passes, its the microwave module, if it still fails. Its likely IF filter module or Frontend.

author: thehater
author_rank: Contributor
timestamp: January 30, 2025, 07:04:57 pm
content: The unit failed frontend 2, as you can see in the attached picture.
RGB csync waveforms don't correspond to what is displayed ?? - Page 1
Forum section: electronics / repair

author: bigboss59
author_rank: Contributor
timestamp: April 21, 2020, 04:46:54 pm
content: Hello,I might have an apparently damaged control board which drive a LCD assembly (attachment)The LCD assembly is working alone with power and a composite NTSC signal.This motherboard can't be buy anywhere or a whole used unit must be buy... (cost 3K as it's very rare)I don't have any information on the control board.(The board can send RGB with csync AND composite at the same time (superimpose))I'm focussing on the RGB outputSo I'm trying to check the RGB with Csync signal; it should be 480i from what I understand in the datasheet.So I made a scart cable like this :https://en.wikipedia.org/wiki/SCART- pin 20 and 17 for Csync- pin 5,7,9,11,13,15 for RGB- pin 8 at 12V- pin 16 at 1.8V (resistor divider using 12V and RGB grounds)I didn't take the terminaison of 75ohms into account !Problem SOLVEDI connect it to a scart TV that support 480i and I got a full white screen however according to the waveforms I don't think that's correct ?If a full white picture was send I should have all channels to 0.7V during 50uS, right ?Timing seems to be correct according to the datasheet.The measurment was done when connecting to the TVDon't hesitated to ask any details or give me some hints/advice.Best regards
RGB Fresnel Lights Not Dimming Evenly - Page 1
Forum section: electronics / repair

author: paul_g_787
author_rank: Frequent Contributor
timestamp: October 12, 2024, 03:07:08 pm
content: We have some Chinese cheap RGB Fresnel lights. The problem I am experiencing with all of them is that the green channel turns on too early. It is like the dimmer is coming on too bright too soon.They are PWM operated dimmers.Any thoughts?Maybe an incorrect resistor value on the green channel?I will gut one apart at the first opportunity.Will post back with more detail as soon as I can.

author: themadhippy
author_rank: Super Contributor
timestamp: October 12, 2024, 04:09:02 pm
content: QuoteQuotecould be the answer.How are you controlling them?if its from a dmx desk id double check the fixture profile is correct, you maybe able to adjust the dimmer curve for the green channel on the desk as a bodge .Other thing take look through the menus ,if any,and double check the settings in the lantern .

author: paul_g_787
author_rank: Frequent Contributor
timestamp: October 14, 2024, 11:23:56 am
content: We have tried it from our "good desk" and also and old school dmx desk thats doesnt have profiles. It does the same on both.If slowly inch up the channels thre green turns on slightly before RBW and A do