hybridfree/eevblog-posts huggingface dataset:
Repairing a DVD player - Page 1
Forum section: electronics / beginners

author: R4v3n5
author_rank: Newbie
timestamp: July 28, 2017, 07:51:50 am
content: HelloMy cousin gave me his DVD player to see if I can repair it.Upon opening it I could see that the reason was probably the really obviousely leaked cap.Now should I also change all of the other caps, as my logic is telling me that they will probably soon follow or should I just measure them and see.Edit: typos

author: Gyro
author_rank: Super Contributor
timestamp: July 28, 2017, 08:49:31 am
content: Hello, Welcome to the forumWholesale replacement of all the caps is probably going to be a false economy. In a switchmode power supply it it only the stressed ones on the output side that tend to fail. Look for bulging tops and leakage on the other ones and replace any likely suspects. The high voltage reservoir cap on the primary side almost never suffers.I don't know your level of experience but you should be very careful working on mains powered equipment - and mains powered SMPSs in general. Be aware that the High voltage capacitor can sometimes retain charge that can give you a nasty belt. Check it with a meter before woring on the supply. Check carefully for solder splashes etc. before to re-fit it and apply mains.Edit: Snap!

author: R4v3n5
author_rank: Newbie
timestamp: July 28, 2017, 10:36:48 am
content: I forgot to mention that I meant only the caps on the psu.For measuring I have a chinese component tester which also shows ESR values.For my experience I am studying electrical engineering and I always make sure the caps are discharged before doing anything.I will take some photos once I get home from work.

author: NivagSwerdna
author_rank: Super Contributor
timestamp: July 28, 2017, 10:42:32 am
content: Quite a while back I fixed mine...I seem to remember that I had to replace a couple to get it to work... the most obvious candidate didn't actually solve the problem. I only replaced a couple though and those had obvious bulging leakages.

author: R4v3n5
author_rank: Newbie
timestamp: July 28, 2017, 03:21:36 pm
content: As promised here are the photos.https://app.box.com/s/n1sk5r5zlbh75zl4u0jaij7tzr4le9isIf you would like any more photos just tell me.

author: senso
author_rank: Frequent Contributor
timestamp: July 28, 2017, 03:23:45 pm
content: Replace them all, one is already burst open.Get something semi decent if you can, try to use TME, their shipping is very decent and its "near" you, so 2-3 days or less of waiting time.
Repairing a iPad broken flex cable, judge my soldering. - Page 1
Forum section: electronics / beginners

author: victor
author_rank: Regular Contributor
timestamp: August 09, 2015, 12:09:11 am
content: The video is available in 4K. The scale is graduated in millimeters just for reference.A broken iPad 2 flex cable, chepo soldering iron, and hair sized enameled wire.I just wanted to share it with you guys.I actually soldered through the viewfinder, which made my life much harder, because I had no sight of view, due to the really narrow distance of the camera lens. Almost burned the camera tho. hahahaIt worked in the end, no need for expensive stuff.

author: lapm
author_rank: Frequent Contributor
timestamp: August 09, 2015, 04:51:06 am
content: Nice that you were able to repair it... Next step, protect those connections and those thin copper wires from stress..What sort of soldering iron were you using? Looked little like my first 10$ special, it was more appropriate to fix sheet metals then soldering components..

author: Duffrageous
author_rank: Newbie
timestamp: February 02, 2016, 11:29:23 pm
content: I didn't think this could actually be done. I've torn a handful of flex cables while installing iPhone screens. If you're up for it, I can scrounge for a bunch of screens with torn cables although you're probably better off learning the ins and outs of fpc connector repair because that's the most common damage.Sorry for the bump.

author: DivineChaos
author_rank: Regular Contributor
timestamp: February 03, 2016, 12:01:07 am
content: I've repaired some interesting stuff with some crazy things (like a heated paperclip) but this definitely takes the cake.Good job.

author: crispy_tofu
author_rank: Super Contributor
timestamp: February 03, 2016, 01:24:55 am
content: Very cool!
Repairing an Amprobe RS-1 - Page 1
Forum section: electronics / beginners

author: Renegade
author_rank: Regular Contributor
timestamp: February 18, 2016, 03:23:39 am
content: I've inherited an Amprobe RS-1 clamp meter. It has some sentimental value, so I do not want to destroy it or damage it.It is currently non-functional. (No pun intended.)I don't know how to open it up. It could be a dead battery or a blown fuse, which would be simple enough to do... **IF** I knew how to open it up.I've downloaded the RS-3 PDF manual, but it doesn't help other than a phone number. (I'll call that later probably.)Here's the Radio Museum page for the RS-3, which is nearly identical to the RS-1 for these purposes. It has pics.http://www.radiomuseum.org/r/amprobe_rs_3rs.htmlDoes anyone know how to open up one of these units?Thanks in advance for any help or pointers.

author: jeroen79
author_rank: Frequent Contributor
timestamp: February 18, 2016, 06:33:05 am
content: No screws visible? Perhaps under a label?If not you could try prying around the seam to see if it unclicks.

author: Renegade
author_rank: Regular Contributor
timestamp: February 18, 2016, 06:53:37 am
content: Quote from: jeroen79 on February 18, 2016, 06:33:05 amI also posted on Reddit, and it turns out that there are hex nuts on the back. I couldn't see what they were before due to some obstructions and some stripping. They looked like round bolts (or just round) until I looked with a loupe.Now I just need to figure out how to unscrew the hex bolts/nuts. I don't have any pliers that thin, or any ratchets thin enough to work.
Repairing Loose Oscilloscope Probes - Page 1
Forum section: electronics / beginners

author: Technobabble_
author_rank: Regular Contributor
timestamp: February 03, 2018, 03:23:14 am
content: Hello,I received a few Tektronix P6131 oscillscope probes, however the BNC connectors seem loose. When I tap on them I get artifacts on the oscilloscope. I double-checked with my new probes and confirmed that it wasn't an issue with my scope. Is there a way I can save the probes? Would spraying contact cleaner into the BNC connectors be a no-go?Thank you.

author: daedalux
author_rank: Contributor
timestamp: February 04, 2018, 09:48:43 pm
content: You can spray contact cleaner on the golden tip, sparingly. If that doesn't work and you know the oscillocope female plug is good (look carefully for that), before throwing the probe away you can change the bnc connector taking care of removing the least coaxial lenght possible. It's not a regular coaxial cable but a resistive one.

author: Paul Moir
author_rank: Frequent Contributor
timestamp: February 04, 2018, 10:04:18 pm
content: Note that the probe cable can be detached from the compensation box. Sometimes the connection there gets dirty and needs to be reseated or cleaned.

author: Electro Detective
author_rank: Super Contributor
timestamp: February 04, 2018, 10:41:03 pm
content: I reckon there will be some tarnish or oily film in there somewhereor the Tek probe tips are a bit thinner perhaps?

author: macboy
author_rank: Super Contributor
timestamp: February 05, 2018, 06:22:23 pm
content: Here is how to disassemble to clean the BNC pin and inspect the innards:1. First remove the tapered compression nut holding the cable in place.2. gently pull the cable from the compensation box.3. Remove the plastic casing from the compensation box. Be careful, the plastic may have become brittle over time. (If you break it, plastic model glue can work well, especially the solvent types e.g. "Tamiya extra thin cement"). I use only my fingernails to separate and pry apart the two halves.4. Remove the BNC. You will need a thin wrench to get in there. I use a bicycle hub wrench which is basically cut from sheet steel, a couple mm thick.5. the center pin of the BNC stays with the compensation box. You now have easy access to clean the corrosion off it. Very careful work with a rubber (not vinyl) pencil eraser followed by IPA cleanup works well for me.6. The box halves now separate so that you can inspect the inside for bad solder joints, etc. Don't mess with the HF compensation trimmers you find in there!When replacing the plastic clam shell over the compensation box, note the orientation. If you get it wrong, the label will be upside down (when plugged in to a scope) and the LF compensation trimmer will not line up with the access hole.

author: Technobabble_
author_rank: Regular Contributor
timestamp: February 10, 2018, 08:57:14 pm
content: Thank you all for replying, I will try and save them.
Repairing mini DJ Controller - Page 1
Forum section: electronics / beginners

author: Topher
author_rank: Newbie
timestamp: January 09, 2021, 08:51:10 pm
content: Hi you all.I've got this cute Numark DJ Controller that I dug out of storage after a couple of years, plugged it in and all I get is one of the lights briefly flashing and then nothing.Its power comes from a USB cable which goes into my mac, the end that goes into the controller is a USB type B mini connector. I've tried a different cable and get the same problem. The light always flashes for a split second when cable is partly plugged into the socket, whether that's at the mac's end or the controller's end, it's always the same quick flash when it's partially connected.Can upload pics/videos whatever if it makes it easier.TaTopher

author: CJay
author_rank: Super Contributor
timestamp: January 09, 2021, 08:54:17 pm
content: Always pics, it's like trying to describe the sounds of music without them.

author: Topher
author_rank: Newbie
timestamp: January 09, 2021, 09:26:53 pm
content: ye fair enough:
Repairing tweeters in stereo system - Page 1
Forum section: electronics / beginners

author: bob.mcc.ct
author_rank: Newbie
timestamp: November 14, 2023, 08:56:28 pm
content: I have a B&W 700 system of speakers. They are 20-years old and the tin foil tweeter domes have failed in two speakers. I have purchased replacement domes and need a glue to firmly attach their foam seal to the metal tweeter assembly. Can someone tell me what type glue to use?Thank you!Bob McConnell

author: Jeff eelcr
author_rank: Frequent Contributor
timestamp: November 15, 2023, 12:26:17 am
content: Pictures would help, although the place that sold you the replacement parts should also know what type of glue would work best in your application. (IF needed)Certain glues can be corrosive and will outgas these should be avoided around small VC wires.Jeff

author: darkspr1te
author_rank: Frequent Contributor
timestamp: November 15, 2023, 05:30:15 am
content: When i used to repair speakers we used two types of glue,for the larger speakers and it's rubber to metal frame you need a "rubberized glue" ,for smaller speakers of foil or paper to a mount then "contact adhesive" is normally used,each glue type has different application instructions so follow whats written on the container.most do require removal of old material,cleaning and then preparation prior to application of the glue.darkspr1te
repairing washing machine board Samsung Q1235V - Page 1
Forum section: electronics / beginners

author: Daxxin
author_rank: Regular Contributor
timestamp: May 25, 2019, 05:29:56 am
content: Display pop up for some seconds then goes off maybe protection thing the critical component IC DIP8 TNY267Pacross pin1 and 8 with unsoldered C38 i get 80ohm is that normal for this IC?

author: Arjunan M R
author_rank: Regular Contributor
timestamp: May 25, 2019, 06:09:52 am
content: Here is the block diagram of tny267P

author: Arjunan M R
author_rank: Regular Contributor
timestamp: May 25, 2019, 06:10:41 am
content: https://www.power.com/sites/default/files/product-docs/tny263_268.pdf

author: Arjunan M R
author_rank: Regular Contributor
timestamp: May 25, 2019, 06:13:30 am
content: Pin 1 and 8 should not be shorted.You have to replace the ic.

author: Arjunan M R
author_rank: Regular Contributor
timestamp: May 25, 2019, 06:15:15 am
content: here is the pin names

author: Arjunan M R
author_rank: Regular Contributor
timestamp: May 25, 2019, 06:16:39 am
content: I think the zener might be shorted in the ic it is right across 1 and 8.Replace the ic

author: Arjunan M R
author_rank: Regular Contributor
timestamp: May 25, 2019, 06:17:21 am
content: Quote from: Daxxin on May 25, 2019, 05:29:56 amNo its not normal look at the block diagram

author: Arjunan M R
author_rank: Regular Contributor
timestamp: May 25, 2019, 06:20:55 am
content: Or the mosfets?

author: Arjunan M R
author_rank: Regular Contributor
timestamp: May 25, 2019, 06:37:37 am
content: I think TNY2xx IC are like rifa caps.Some time ago tny277p in the psu of my computer blowed up with a loud sound.I replaced it and the psu was fine.

author: Arjunan M R
author_rank: Regular Contributor
timestamp: May 25, 2019, 06:38:39 am
content: In the datasheet it says not recommended for new designs

author: Arjunan M R
author_rank: Regular Contributor
timestamp: May 25, 2019, 06:41:07 am
content: Quote from: Daxxin on May 25, 2019, 05:29:56 amYeah it has protection.

author: Arjunan M R
author_rank: Regular Contributor
timestamp: May 25, 2019, 06:43:30 am
content: Bypass pin(pin1) is the connection point for 100nF external bypass capacitor for internal 5.8V supply.It must not be shorted. It's just for that cap.

author: Daxxin
author_rank: Regular Contributor
timestamp: May 25, 2019, 03:33:04 pm
content: C36 is a levelling o pump ?

author: Arjunan M R
author_rank: Regular Contributor
timestamp: May 25, 2019, 03:36:26 pm
content: Quote from: Daxxin on May 25, 2019, 03:33:04 pmIf you mean C36 is levelling the ic, yes.

author: Arjunan M R
author_rank: Regular Contributor
timestamp: May 25, 2019, 03:38:22 pm
content: Quote from: Daxxin on May 25, 2019, 03:33:04 pmDidnt understand what you mean by o pump

author: Arjunan M R
author_rank: Regular Contributor
timestamp: May 25, 2019, 03:39:53 pm
content: You need to replace the ic to fix it.
Repairs to DC power supplies - Page 1
Forum section: electronics / beginners

author: partyanimallighting
author_rank: Newbie
timestamp: July 27, 2023, 03:54:46 am
content: Hi all, I'm your newest member and I'm looking for a forum to provide me with guidance and advice to repair power supplies, PCB's etc all geared towards the stage lighting industry. My main repair issues are with LED PAR mainboards and power supplies and also a wide variety of 120VAC ~ DC power supplies used in moving heads etc with varying outputs from 12VDC all the way up to 380VDC. I can use a multimeter to some extent and I have all the necessary tools (hand tools, solder workstation etc) with the exception of an oscilloscope and I have the willingness to learn and with proper guidance I may well be able to resolve some of the issues I am having. Anyway, hello to everyone, thanks for hearing me out and look out for my first post very soon.

author: Faranight
author_rank: Unknown
timestamp: July 27, 2023, 09:42:35 am
content: Post a topic with a broken PSU (and preferably with some PCB pictures) in the repair section.Describe what exactly what symptoms the circuit is exhibiting, and we'll continue off from there.

author: tunk
author_rank: Super Contributor
timestamp: July 27, 2023, 11:55:29 am
content: Most newer PSUs are switch mode (SMPS), so you could look into how they work.This may be a start:https://en.wikipedia.org/wiki/Switched-mode_power_supplyAlso, high voltages can be fatal.

author: Ian.M
author_rank: Super Contributor
timestamp: July 27, 2023, 12:22:36 pm
content: See 'Silicon' Sam Goldwasser'sNotes on the Troubleshooting and Repair of Small Switchmode Power Supplies
Reparing a PC power supply - Page 1
Forum section: electronics / beginners

author: menkelis
author_rank: Contributor
timestamp: March 15, 2014, 11:04:07 pm
content: Just asking to confirm something, I am just a newbie at this.I have a 300w PC power supply that is taking about 2 minutes to turn on.So I took it apart and the first thing that jumps out at me is a bigcapacitor that has a bulging top, that is sitting right next to a big heat sink.I have removed the cap and it is marked 2200uF@16vdc.My fluke 87V says that the cap is 900uF, so just to confirm what I am seeingthe cap is BAD and should be replaced.

author: mariush
author_rank: Super Contributor
timestamp: March 15, 2014, 11:05:51 pm
content: Yes. It should be replaced. But keep in mind that if that one is bad, so could the others be in various degrees of "bad", even though they're not swollen.

author: electronics man
author_rank: Frequent Contributor
timestamp: March 15, 2014, 11:11:31 pm
content: What is the temp rating on the cap as if it is next to a heatsink and it is a low temp one (105c) then obviously that is bad design.

author: menkelis
author_rank: Contributor
timestamp: March 16, 2014, 03:52:15 am
content: The cap that is in question is rated 105c.I was able to briefly get the power supply to start up in about 6 seconds, which is a lot better than waiting two minutesbut then it stopped again.With the high density of this SFX power supply and my not so perfect eye sight I thing that I willjust opt to replace it with a new one instead of trying to hunt down everything.

author: mariush
author_rank: Super Contributor
timestamp: March 16, 2014, 10:49:48 am
content: You should also have a look at the 5v Standby capacitor (it should be one rated for 6.3v-10v closer to the heatsinks) and should also look for some smaller capacitors, something like 10-47uF 35-100v which may also be dried out a bit and therefore taking a longer time to indicate "power good" to the computer.
Reparing TV PSU - Page 1
Forum section: electronics / beginners

author: Phaedrus
author_rank: Frequent Contributor
timestamp: January 06, 2014, 09:33:13 pm
content: Pretty easy project, really, just repairing the PSU in a dead Samsung TV in the hopes of making it work again.There are some blown caps on the secondary of course, so I'm replacing all of the electrolytics except the 450V primary cap (since it's expensive and probably ok) with 105C Japanese caps.However, I also found a dead bug that managed to short across two leads of the bridge rectifier (TS4B05G). I tested the diodes with my meter and it tests fine, as well as the PFC fets, but I was wondering if that short might have damaged other nearby components, or the PFC control circuit. Is this likely, and is there any easy way to check?

author: bgsteiner
author_rank: Contributor
timestamp: January 07, 2014, 03:21:23 am
content: any IC's could have gone as well with a dead short like that i would look for any charing or bulging of components or cracks in any IC's

author: Phaedrus
author_rank: Frequent Contributor
timestamp: January 13, 2014, 11:26:47 pm
content: Caps arrived.5x Nichicon 1000uF 25V5x Panasonic 2200uF 10V10x Rubycon 47uF 50V10x Rubycon 10uF 50VAll 105C of course. Even if they don't fix the TV, they're still good, useful caps.

author: Phaedrus
author_rank: Frequent Contributor
timestamp: January 14, 2014, 02:56:13 am
content: Like magic, good as new. But now he wants me to fix his microwave

author: richard.cs
author_rank: Super Contributor
timestamp: January 14, 2014, 10:07:16 am
content: Quote from: Phaedrus on January 14, 2014, 02:56:13 amGood newsMicrowaves are pretty easy to fix (assuming you're serious), I've done loads. A couple of tips: that HV capacitor is deadly, it's almost always the door interlocks that fail.Probably shouldn't go into any more details without starting a new thread.

author: SeanB
author_rank: Super Contributor
timestamp: January 14, 2014, 06:08:28 pm
content: Common faults I see on microwaves are door switches ( fuse blows violently), replace all 3 if you are suspecting them. Also common is the HV diode failing. Symptom is HV fuse blowing along with the LV fuse. Also common is an open circuit capacitor which does not blow fuses but the microwave only heats up slowly.Common is a dying magnetron if cap and diode is fine but low heating. Check as well the fan actually works and blows air and the covers that direct air into the magnetron for cooling are still there so it cools. A blowing oven lamp can pop the fuse as well with no other symptoms other than the light going out, new fuse fixes microwave.Keep a can of roach killer nearby when opening them, they are the perfect breeding place.

author: Phaedrus
author_rank: Frequent Contributor
timestamp: January 15, 2014, 01:25:22 am
content: Heh, he does have a dead microwave, but the part about him asking me to fix it was a joke. I might take a look at it though, so thanks for the advice!
(Sloved, new question)Replace buzzer by a LED on my UPS? - Page 1
Forum section: electronics / beginners

author: sam1275
author_rank: Frequent Contributor
timestamp: May 05, 2015, 05:46:32 am
content: Hi everyone.Is it possible to use a LED to replace the buzzer on the UPS, do I need some resistor in serial?I don't want to just desolder the buzzer without add another indicator because some information cannot be viewed only by it's stock LED.Thank you.

author: Mechatrommer
author_rank: Super Contributor
timestamp: May 05, 2015, 12:31:14 pm
content: Quote from: sam1275 on May 05, 2015, 05:46:32 amyesQuote from: sam1275 on May 05, 2015, 05:46:32 amyes but you need to check the buzzer current limiting resistor how much, if necessary you need to increase that. if the buzzer use ac coupling a capacitor you need to short it out. ymmv.

author: sam1275
author_rank: Frequent Contributor
timestamp: May 06, 2015, 05:04:49 am
content: Quote from: Mechatrommer on May 05, 2015, 12:31:14 pmThank you

author: bitwelder
author_rank: Super Contributor
timestamp: May 06, 2015, 05:29:56 am
content: Actually I have done that for a weather station that had an annoying buzzer to signal upcoming thunderstorms.After a few times the thing started to buzz at night I swapped the buzzer for a small 3mm LED + current limiting resistor.

author: sam1275
author_rank: Frequent Contributor
timestamp: May 08, 2015, 05:15:38 pm
content: Today I took it apart and replaced the LED, working perfect!But I noticed the output is connected to the input directly, so how can it perform AVR?
Replace Carbon Layer with Passive Resistors Components in Attenuator - Page 1
Forum section: electronics / beginners

author: Mechatrommer
author_rank: Super Contributor
timestamp: January 04, 2013, 10:39:58 am
content: i bought 3dB attenuator as in the attached picture. the problem is, i should get 6dB instead of 3dB i only realized it when getting and measuring the item, its 150ohm to ground i expected to be 50ohmmy head still not work too well with dB. now maybe the sloppiness was due to disrespect from previous experience that the internal of my 50ohm terminators are using passive 50ohm TH resistors, so i guess this is the same and i can easily mod this attenuator to suit my need. but i was wrong. upon dismantling it, there is a special carbon layer poured on it, not something i can desolder, take out and keep, removing it means sctratching it to ashes. by looking at the geometry (bottom section of the attached file) and measuring end to end center connector (~17ohm), its probably a T attenuator (3 resistors simplified) and the value as in 3dB table of...orfromhttp://www.allaboutcircuits.com/vol_3/chpt_1/7.htmlso my question is regarding the carbon layer...1) the device is speced to 3GHz BW. is the carbon layer has something to do with this? can i still get the BW by replacing with smd or TH components?2) whats so special about it compared to passive (lumped) components?3) the device is speced as 2W device. but no question here not sure what to ask. i think i can calculate to meet the 2W by using passive components or just by try and error.thank you.

author: PA0PBZ
author_rank: Super Contributor
timestamp: January 04, 2013, 11:14:29 am
content: Quote from: Mechatrommer on January 04, 2013, 10:39:58 amHigh BW means short leads, low L and low C. The carbon layer takes care of that and also takes care of power dissipation. Of course you can replace it with smd or th components, but the result will probably be lower BW and lower power handling. How much lower is hard to say.Your best bet would be to get another one, either 3dB or 6dB.

author: Mechatrommer
author_rank: Super Contributor
timestamp: January 05, 2013, 04:22:06 am
content: right. i should know it all along. nvm i'll exchange higher BW with modificability. i wont be able to design anything near 500MHz, let alone 3GHz. thank you for your thought PA0PBZ. O0
Replace DIP Switches with Tactile button (for EEPROM bank switching) - Page 1
Forum section: electronics / beginners

author: ColorComputerStore
author_rank: Newbie
timestamp: July 25, 2018, 08:32:19 pm
content: Hello, first post here.I want to work on a project that allows me to switch banks on an EEPROM. The original design called for three jumpers to select between EEPROM size and the bank that the user wanted to select. I think I can eliminate one jumper because I will use a specific EEPROM size (still debating 27128 or 27512). So that leaves the selection of which bank to load. I really want to get away from using jumpers as it isn't user-friendly for novices to use jumpers.I want to keep it simple, like a tactile switch that when pressed would move through the settings.I'm hung up on another point. In the current design the user experience is...1) Set jumpers2) Plug in cartridge3) Turn on machine4) Machine loads specific bank based on jumpersBut if I am using tactile switch, it doesn't seem possible to allow the user to simply change in the bank on the fly as that will crash my machine. So user experience needs to be something like...1) Plug cartridge into machine2) Machine loads first bank contents3) User hits tactile button4) Cartridge issues 'reset' command to machine5) Machine loads next bank based on a 'counter'6) Repeat Step 3 to 5 until counter gets to 4 (or 8 for 8KK banks) and change counter back to 1.Hope I am making sense. Very much a rookie.Thanks,

author: David Hess
author_rank: Super Contributor
timestamp: July 26, 2018, 01:11:07 am
content: Might also want it to remember the last setting after being powered down.The easiest way now is probably to use a 50 cent PIC or AVR microcontroller.

author: ColorComputerStore
author_rank: Newbie
timestamp: July 26, 2018, 08:08:37 pm
content: Yes, I was recommended a PIC and AVR as well by someone else. I need to study them as I know ZERO. lol

author: David Hess
author_rank: Super Contributor
timestamp: July 26, 2018, 08:40:58 pm
content: PIC and AVR microcontrollers are remarkably easy and inexpensive to use.A discrete logic version is certainly feasible with several packages or some cleverness. Maybe use a shift register with parallel load on startup to select one bank and then clock it using a pushbutton. A monstable multivibrator could then trigger the reset. A dip switch or jumpers could even select which bank is activated when power is applied. This all might be feasible with a shift register and quad gate so two packages.
Replace FX888D with FX951 ? - Page 1
Forum section: electronics / beginners

author: Kantilo
author_rank: Contributor
timestamp: February 08, 2022, 03:47:27 pm
content: Hello, I have an FX888D, I wanted to know if you think reselling it to eventually buy an FX951 is worth it? Or is it spending money for nothing, knowing that it's not a pro use?What do you also think of the tips for the FX888D that can be purchased on aliexpress, can this damage the device?Thank you

author: David Hess
author_rank: Super Contributor
timestamp: February 08, 2022, 05:18:14 pm
content: Quote from: Kantilo on February 08, 2022, 03:47:27 pmI think it would be a waste of money and effort to upgrade from an FX888D to an FX951.QuoteThe heater and temperature sensor is built into the FX888D pencil so I do not see how a bad tip could damage it except if it did not fit and you forced it.

author: wraper
author_rank: Unknown
timestamp: February 08, 2022, 05:29:51 pm
content: Quote from: Kantilo on February 08, 2022, 03:47:27 pm951 is certainly better if you get a genuine one with genuine cartridges. But I would not buy D version it because of perverted UI.QuoteThey are garbage in general. No damage will happen but performance will suck compared to genuine tips.

author: rpiloverbd
author_rank: Regular Contributor
timestamp: February 13, 2022, 03:17:26 pm
content: I think you'd better continue using your existing FX888D. Compared to the high price, FX951 doesn't really offer anything extraordinary.
Replace Selenium Rectifier with diode? - Page 1
Forum section: electronics / beginners

author: Crambone
author_rank: Frequent Contributor
timestamp: September 06, 2022, 10:10:44 pm
content: Hey guys I can use some help here I need to replace the Selenium Rectifier in this TC-2 and was wondering if I can use a 1N4007? Also would I require a resistor after the diode as I believe the Selenium’s have some resistance to them?I attached a copy of the schematicThanks, Drew

author: strawberry
author_rank: Super Contributor
timestamp: September 06, 2022, 11:01:37 pm
content: switching diodes have more voltage drop0.5ohm wont give much difference in this circuit

author: floobydust
author_rank: Super Contributor
timestamp: September 06, 2022, 11:05:22 pm
content: You can replace the selenium rectifier diode with something like a 1N4004-1N4007. Yes a silicon diode has much less voltage drop compared to a selenium stack, but with the Heathkit you have 75k series resistor and potentiometers and calibrate before using so I don't expect any problems.For increased safety, I would add a fuse and grounded line cord.

author: bdunham7
author_rank: Super Contributor
timestamp: September 06, 2022, 11:13:04 pm
content: How many plates does the existing selenium rectifier have? I agree withfloobydustthat you can probably just use a 1N4007 without modification, but if it doesn't work out or you can't get it back into calibration, a resistor isn't going to be the fix due to the low and variable current involved. You'd have to add many diodes in series or a zener to match the voltage drop of the original selenium rectifier, which is a bit more than a volt per plate.

author: floobydust
author_rank: Super Contributor
timestamp: September 07, 2022, 12:41:06 am
content: Is it copper-oxide? I don't remember copper-oxide in the 450V league, see them only in VU meters, pic is here:https://antiqueradios.com/forums/viewtopic.php?f=8&t=223323Same circuit in Heathkit IT-1, IT-3317 except the rectifier is a 56-26 or 1N191 90PIV 5mA Ge, R9 1,000Ω - instead of IT-2 using 57-6 copper-oxide? diode; only data I can find is 450PIV, and used with 1,200Ω.So the voltage divider resistor was lowered from 1,200Ω to 1,000Ω that must be to cover the lower Vf.I also see mods to prevent the meter from pegging too hard (adding clamp diode).
Replace Single Turn Potentiometer with 10 Turn Precision Pot on Lab Power Supply - Page 1
Forum section: electronics / beginners

author: ert829
author_rank: Newbie
timestamp: March 07, 2014, 08:09:53 pm
content: I have a new lab power supply which has single turn 10K potentiometers on it. It is difficult to set precise values with these pots. I would like to replace some them (voltage) with 10 turn 10K pots. But...I noticed that the minimum resistance on these devices is 100 Ohm, not zero, like I measured on the single turn pots. I suspect that this will be a problem. Any thoughts out there?-ert829

author: uwezi
author_rank: Unknown
timestamp: March 07, 2014, 08:39:15 pm
content: What's in the specs is not always what you see in reality. It is what the manufacturer is willing to guarantee.I have not seen a 10-turn pot which would perform worse than a 1-turn pot with regard to lowest resistance.

author: SeanB
author_rank: Super Contributor
timestamp: March 07, 2014, 08:41:56 pm
content: If they fit behind the panel just replace them Any 10 turn pot of reasonable quality will have lower end travel resistance than most single turn composition pots. If you need lower resolution look for some 3 turn or 5 turn pots instead, they are shallower.

author: Golana
author_rank: Newbie
timestamp: March 07, 2014, 10:00:02 pm
content: I would recommend these:http://www.digikey.com/product-search/en?vendor=0&keywords=3590S-2-103L-NDI replaced some single turn pots with these on a cheap Mastech power supply and they have been working great for several years. Minimum resistance is 1Ohm. They are a bit bulky but if you have room for them they are great quality.

author: plesa
author_rank: Frequent Contributor
timestamp: March 07, 2014, 10:20:50 pm
content: Quote from: ert829 on March 07, 2014, 08:09:53 pmThe Vishay 534 Spectrol can go down to bellow 0.05 Ohm, measured on 10k.http://se.farnell.com/vishay-spectrol/534b1103jlb/pot-rotary-10k-20-6mm-5/dp/1144786

author: JOERGG
author_rank: Contributor
timestamp: March 08, 2014, 10:02:09 am
content: I dropped the idea of inserting a 10 turn pot in my power supply, because i could not find knobs for a 6.35mm axis and thought that it was to expensive to realize later that a 6mm knob will not fit.Does a 6mm knob fit onto the slightly thicker axis or how did you solve this problem?

author: Psi
author_rank: Super Contributor
timestamp: March 08, 2014, 10:12:13 am
content: Quote from: JOERGG on March 08, 2014, 10:02:09 amSearch for 1/4" knobs insteadTrying to find 6.35mm knobs is like trying to find a M6.35 machine screw.

author: JOERGG
author_rank: Contributor
timestamp: March 08, 2014, 10:27:27 am
content: Quote from: Psi on March 08, 2014, 10:12:13 amThat makes sense, thank you so much, how blind can one be if not to be used to calculate with inches. I really couldn´t see it.
Replace Whole Board, or just Components? - Page 1
Forum section: electronics / beginners

author: gaddy996
author_rank: Contributor
timestamp: February 12, 2014, 08:23:36 am
content: Hello There, i have Velodyne Sub-woofer that has been effect by an lighting strike down the mains. The strike blew the fuse and managed to blow components in one of the driver boards. The PCB board number is E230194 HX-008. Would it be too hard to replace the blown components? Or should i just replace the entire board?I have linked the photos of the blown board....Thanks..

author: Kjelt
author_rank: Super Contributor
timestamp: February 12, 2014, 09:00:28 am
content: Before you start, did you call your insurance company? Depending on your contract, Lightning damages can be covered and in that case you should let the insurance company take care of itBut to start answering your original question, my little experience with lightning damaged electronics is that there can be a lot damaged that can not be seen from the outside. I tried repairing once and had to replace 80% of the electronics before it worked again. You can be lucky, but lightning damages can be very very bad (evaporated pcb traces, inside ic damages, etc. etc.).

author: gaddy996
author_rank: Contributor
timestamp: February 12, 2014, 10:04:52 am
content: Nope my insurance doesn't cover itWell it looks like the explosion of the components may have damaged some other SMDs. It looks like ill just replace the entire board then, thanks for the reply just wanted another opinion

author: Ionelungurean
author_rank: Newbie
timestamp: November 21, 2014, 10:16:20 pm
content: Hi,it happened same to me!!!how did it end?did you replace the whole board?and if so...where did you buy it from?Thanks

author: kingofkya
author_rank: Regular Contributor
timestamp: November 22, 2014, 05:03:19 am
content: Depending on your requirements you can get some generic amp replacements off ebay you can drop in with some minimal rewiring.http://www.ebay.com/sch/i.html?_odkw=class+D+amp&_from=R40&_osacat=0&_from=R40&_trksid=p2045573.m570.l1313&_nkw=class+D+amp+kit&_sacat=0
Replaced Desk Lamp With New G4 12V 20W Bulb but it Blinks? - Page 1
Forum section: electronics / beginners

author: Boris_yo
author_rank: Frequent Contributor
timestamp: April 07, 2013, 02:08:00 pm
content: I have had my previous bulb malfunctioned so I decided to buy new and I have got smaller G4 version of old. You can see image below to compare both. The problem with new one is that it starts blinking after a few seconds and you can hear quiet zapping if you stare closely. This was actually the case with old bulb before it malfunctioned and below is video I recorded about new bulb:Do you think I have problem in desk lamp's upper section? Should I check something with multimeter or wipe specific area?

author: Boris_yo
author_rank: Frequent Contributor
timestamp: April 21, 2013, 08:04:10 am
content: My bad guys. I after posting this question it seems I have accidentally locked it from replies. It is now open and everyone is welcome to shed some light on this question.

author: SeanB
author_rank: Super Contributor
timestamp: April 21, 2013, 09:59:43 am
content: Dying electronic ballast in the base of the lamp is most likely, along with a burnt lamp holder base. You can see on the new lamp the legs are going brown from overheating in the middle.

author: orbiter
author_rank: Frequent Contributor
timestamp: April 21, 2013, 02:49:07 pm
content: Have you tried another new bulb? If so and it still flickers. I think I'd be suspecting the ballast/transformer too.

author: blasto9000
author_rank: Contributor
timestamp: April 22, 2013, 08:01:23 pm
content: Thermal expansion breaking the contact... light goes out, cools off, makes contact again.Does the old lamp also have G4 pin spacing? In the photo it looks like larger pins and spacing. Maybe the pins on the new G4 are barely making contact when cold.

author: Boris_yo
author_rank: Frequent Contributor
timestamp: April 23, 2013, 07:46:46 am
content: Quote from: blasto9000 on April 22, 2013, 08:01:23 pmYeah, the new has pins that are shorter in length and in spacing between 2 pins.

author: rentner
author_rank: Regular Contributor
timestamp: April 23, 2013, 07:54:11 am
content: What are you all talking about electronics? :O Isn't that just a simple transformer, a Fuse and a Switch? If so, I'd say, eather the Transformer has a fault, maybe the built in termal fuse, Primary windings or Switch. if not, I am absolutely not sure. Than s omething in the upper section could be wrong. Can you screw it open and post a picture of the lamps upper section after screwing it open?
Replacement 10A fuse for the ANENG 8008 - Page 1
Forum section: electronics / beginners

author: ledtester
author_rank: Super Contributor
timestamp: April 03, 2018, 11:56:18 pm
content: So I decided to measure voltage right after measuring current without switching the probes around and... blew the 10A fuse in my ANENG 8008 meter.The fuse measures 3.6mm x 10mm, rated 10A, 250V, fast blow and mounted in a clip fuse holder.I just want to make sure that this part from Mouser is an acceptable replacement:https://www.mouser.com/ProductDetail/Littelfuse/0874010MXEP?qs=sGAEpiMZZMtxU2g%2f1juGqakp2AIQxTJs7FPFfuEa%2fGQ%3dIt has axial leads which I figure I'll just snip off.Also, is anyone aware of other sources for this kind of fuse?

author: Fsck
author_rank: Super Contributor
timestamp: April 04, 2018, 12:44:34 am
content: If it fits, it'll work. (Whether safe or not is a different matter)On another note, 50A breaking capacity, really? I guess the length being what it is would really put a cramp on that. Probably fine on low energy circuits, but even the UK plug fuse things are like 6kA breaking capacity fused.

author: mdijkens
author_rank: Regular Contributor
timestamp: April 04, 2018, 12:05:35 pm
content: I've bought a set of these:eBay search: "FUSE, 3.6X10MM, 10A, 250V, F (LOT OF 10)"
Replacement Cable for SYV-50-3 - Page 1
Forum section: electronics / beginners

author: AK-Survey
author_rank: Newbie
timestamp: December 04, 2018, 01:14:12 am
content: Hello,I'm looking to replace an existing cable as part of my company's GPS survey system. We have an external radio for increased range. The existing cable is labeled "SYV-50-3 8352M." I found this to be manufactured by Lianstar in China (link to product:http://www.lianstar.com/en/SYV-50-cable.php). We have this set up with TNC connector on one end, with the other end directly into our antenna base mount. I see no indication whether this is SYV-50-3-1 or 50-3-4.What I'm looking for is a good replacement cable that would replace this as it gets very stiff in the cold. My primary conditions are sub-arctic to arctic use (i.e. needs to be flexible to at least -40F/C) and repeated flexing, even when cold. We don't plan on a length greater than 10 ft. I have been told by separate sources that this is essentially RG-58, and also that it is replaceable with LMR-240.Can anyone give suggestions before we invest in a potential custom-built cable? We're running up to 35W, 450-475MHz.Thank you,David
Replacement ceramic caps. - Page 1
Forum section: electronics / beginners

author: ThinkingGrenade
author_rank: Newbie
timestamp: January 11, 2020, 02:06:32 pm
content: ok, needed some replacement ceramic caps for a project. replacing some 30 year old stuff, ordered and these arrived. ( small blue ones)rated 4700pf at 3kv. - tested also, capacitance is accurate. - am i being an idiot, or have components just shrunk? schematic for device doesnt list any other info than that.....

author: Twoflower
author_rank: Frequent Contributor
timestamp: January 11, 2020, 02:23:00 pm
content: Yes, ceramic caps shrunk a lot. Just look at the SMD caps. I remember the time ceramic caps are only in pF ranges. Now you can get them up fo several µF. Not sure about the high voltage ones, but that one looks still reasonable.But you should not use the blue one as to me it looks like the old one is an X-Rated cap . Unless it is X-Rated too which is not visible on the picture. Most likely the part sits in the mains input stage of the device. You must replace it with an X-Rated cap.

author: ThinkingGrenade
author_rank: Newbie
timestamp: January 11, 2020, 02:42:40 pm
content: Quote from: Twoflower on January 11, 2020, 02:23:00 pm1kv EHT section of an oscilloscope. after the main PSU. on a separate board.

author: wraper
author_rank: Unknown
timestamp: January 11, 2020, 03:09:03 pm
content: Unless you are replacing faulty parts, replacing such ceramic capacitors is a waste of time. Won't do any good and only could cause damage in the process. It might have less stable dielectric too. So simply buying same capacitance and voltage spec might be not good enough. Also if you bought it from china it may easily have fake voltage rating.

author: wraper
author_rank: Unknown
timestamp: January 11, 2020, 03:17:23 pm
content: Quote from: Twoflower on January 11, 2020, 02:23:00 pmNone of them are safety rated. Also you might mean Y rated.

author: magic
author_rank: Super Contributor
timestamp: January 11, 2020, 03:33:44 pm
content: LOL, 24Mpix and 3.6MB to show a pair of capacitors has to be the new record on this forumAnd don't google what "X-rated" means...

author: Twoflower
author_rank: Frequent Contributor
timestamp: January 11, 2020, 05:18:39 pm
content: Quote from: wraper on January 11, 2020, 03:17:23 pmI got suspicious as the original part shows an X before the value. Maybe I was wrong estimating the security rating.Actually the right word is not rated but class. Sorry, if I caused some trouble...

author: Benta
author_rank: Super Contributor
timestamp: January 11, 2020, 07:42:03 pm
content: IMHO, the old cap is not ceramic, but silvered mica... very common for high voltage safety approved caps. Personally, I wouldn't replace it with a ceramic cap.

author: Gyro
author_rank: Super Contributor
timestamp: January 11, 2020, 07:53:07 pm
content: No, it's a standard ceramic disc. You never got silvered Mica in a circular form factor. I've never seen silver Mica used for safety applications, just RF and precision.It's also pointless changing it unless it's actually faulty, which is unlikely. You can take a change old capacitors on sight fetish too far.
Replacement for BC557 / BC548  - Page 1
Forum section: electronics / beginners

author: chinoy
author_rank: Regular Contributor
timestamp: June 02, 2024, 05:58:02 pm
content: So an old circuit has these two transistors in SOT23 SMD package size.As per the info I have the old transistors were 100v 50 MAAmplification does not matter. i.e. hfe values do not matter.Speed does not matter.Id like to pick a PNP / NPN pair in SMD SOT 23 which can support the highest voltage and highest mili amps.What would be a good option.

author: tooki
author_rank: Super Contributor
timestamp: June 02, 2024, 08:13:59 pm
content: Why not replace them with the same types? Those are super-common types.Your existing documentation is somewhat wrong, in that the part number changes depending on the package. BC5xx (THT) ≡ BC8xx (SMD) for many parts, for others, the number even changes more.In this case, BC557 ≡ BC857 and BC548 ≡ BC848.Or are you attempting to find “upgraded” parts that can handle higher voltages and currents? In that case you need to share the full schematic and all the info you have, and what you want to achieve.

author: Doctorandus_P
author_rank: Super Contributor
timestamp: June 03, 2024, 06:50:36 am
content: Most of the bigger stores have parametric search engines for the stock they have. A quick check suggests MMBT3904 (40V 200mA) costs less then 3ct (when buying 100).When sorting by Collector emitter voltage ZXTN08400BFFTA is on top of the list. It goes up to 400V and 500mA, but costs 35ct (quantity 100).When sorting by Collector current, ZXTN19020CFFTA is on top. It goes up to 7A, but only 20V and costs 45ct (100 up).In another store I sort of randomly picked FMMT493TA (100V 1A 500mW SOT23) for 13ct (25+)There are thousands of choices for a BJT in SOT-23 package, and when you go to more "exotic variants" (higher current and voltage, or other extreme) they become more expensive. I suggest you try the search and sort functions of those stores. With smaller (local?) stores their offerings are much more limited, and without search options, but often you can scroll though the whole list, and often they have some balance in what they offer.Another option is to buy an "transistor sample book" from China (amazon, ebay, aliexpress, etc). A quick search shows you can get a book with 60 different transistors, 25 of each (total 1500) for around EUR20. Those books are not all the same. Some may have a more differentiated content then others, so get the datasheets and make some comparisons before you buy such a book.

author: Terry Bites
author_rank: Super Contributor
timestamp: June 03, 2024, 01:34:04 pm
content: Yes, the ubiquitous 3904/ 3906 are great general purpose transistors. Available as through hole and SMD.Keep a small stock of medium power types, eg ZTX651, ZTX751. Not so cheap but very handy and very avaialble. How often will you really need to go above 40-60v?I use Zetex FMMT555 and FMMT4555 types for >60V. $0.10 in quantity.

author: aliarifat794
author_rank: Regular Contributor
timestamp: June 05, 2024, 08:49:10 am
content: You can consider MMBT5551 (NPN) or MMBT5401 (PNP)
Replacement for MCP6001 - Page 1
Forum section: electronics / beginners

author: DarkZero
author_rank: Regular Contributor
timestamp: September 14, 2012, 05:29:11 am
content: plz if someone can tell me some replacements for this op amp MCP6001and if someone know which two mosfets i can use instead of FDC6420C or a replacement packagethx in advance

author: AlphZeta
author_rank: Regular Contributor
timestamp: September 14, 2012, 05:14:06 pm
content: You can try either AD8541 or OPA344. Both come with the SOT-23. The only thing for MCP60001 is that it's voltage can go as low as 1.7V (whereas the other two only goes down to 2.5V). MCP6001 is just a general purpose OP amp so I am sure that others can suggest more that they are familiar with.As for the complementary MOSFET, I don't know any 6-pin varients.... sorry.

author: DarkZero
author_rank: Regular Contributor
timestamp: September 15, 2012, 01:31:44 pm
content: Thx for the reply I'm trying to build that pickit2 thing and i only miss op-amp and that transistor package i found a supplier for MCP6002 and i could use 2 mosfets i just don't know which one's I'm really bad with datasheets