hybridfree/eevblog-posts huggingface dataset:
QNAP NAS - 12v 0.3a - 1x SMD ceramic cap seems bad - Page 1
Forum section: electronics / repair

author: nerdynerd
author_rank: Newbie
timestamp: July 08, 2022, 12:24:04 pm
content: I like to tinker as a hobby and have lots to learn still, please bare with me if I've made any obvious mistakes in my understanding / troubleshooting. Happy to post images if this helps.I was given a QNAP TS-431P which seems ""dead" bar that the fan spins when you apply power. I do not have the original PSU (12v 7.5a) but I am using a Riden RD6012 bench PSU to power the unit at 12v 7.5a.I'm very comfortable with soldering and have replaced caps, transistors & BIOS chips before with success, while keeping my work looking professional.In the QNAP & r/qnap pages there are many reports of the same model dying, especifcally after not being used for while, which was the case with this as my friend used it 6months back and then put it in his cupboard.Tools available or used so far: Uni-t UT61E multimeter (fluke leads), older fluke meter, Uni-t UT658 USB power tester, soldering iron (not used on this job yet), USB BIOS reprogrammer (not used on this job yet).Symptoms:1.Fan spins as soon as power is connected to the DC jack. Power button does not apprear to be stuck or shorted.2.An HDD will spin if inserted into any of the slots.3.No front LED's turn on or flash (status, power, USB, HDD1-4).4.Front USB does not give charge - tested with multimeter & USB voltage tool.5.Reset button does not seem to have any effect, despite that I can feel it being pushed down.6.No beeps.7.Neither of the 2x network ports 2x LED's flash when powering on the device.Multimeter continuity troubleshooting:DC jack - 6x through hole - 5x points beep on ground. 6th does not.DC jack - ground to EC18 - only 1 side beeps.DC jack - ground to EC20 - both sides beep.DC jack - ground to EC12 - only 1 side beeps.EC20 - bottom of the PCB, under the CPU - beeps on both sides when tested to ground. At first I didnt detect this but on a second run it did & it seems that I really have to push the leads hard against each end of EC20, unlike any of the other ECxx or Cxxx components.No other ECxx or similar sized Cxx component does this.If I test continuity between Ec20 and EC18 being the closest EC, with about 10millimeters between them, then my multimeter beeps when my probes are on the outside of these EC's, aswell as from the outside of EC18 to the inside of EC20.Resistance mode: Probes places on each side of the respective EC.EC20 - under the CPU = 22.xxEC18 - just outside of the bottom of the CPU - (Could be EC16 can't really see the text well) is right next to it however = 166.xxEC12 - under the CPU = 112.xxResistance mode: Probes places on ground (DC jack) and on each side of the respective EC, one side at a time obviously.EC20 = +- 0.57 & +-166 on the side marked positive.EC18 = +- 0.13 & 22.xx - I assume this side is positive? Cant see any markings.EC12 = 0.13 & 112.xx on the side marked positive.I'm a total amateur with this kind of stuff but this leads me to wonder if EC20 is the problem / part of it. Any advice / corrections etc would be greatly appreciated!
QNAP TVS-472XT repair - Page 1
Forum section: electronics / repair

author: georgedone
author_rank: Contributor
timestamp: November 03, 2022, 01:09:05 am
content: I have a QNAP TVS-472XT nas which recently failed. According to reports on Internet, reddit, etc there is a problem similar to the C2000 bug but in this case is the chipset chip, a Intel B360 PCH (Platform controller Hub).Many TVS-x72XT failed after 2-3 years.There is a video on youtube from someone who claims repaired hundreds of TVS-x72XT nasses with this defect by replacing the B360 PCH.I looked on the usual places but I cannot find anywhere to buy this chip. I have the expertise and equipment to solder it but only of is a new or reballed chip, I do not have the stencils or the expertise to do reballing myself otherwise I would buy the cheapest PC motherboard with B360 chipset and transplant it to the Qnap.A strange thing is that I saw no reports from anywhere else that B360 have a problem causing MOBO failure so I'm wondering if is indeed a chip bug or is related to specific implementation of TVS-x72 causing the chip to fail prematurelly.
QUAD 2C Pick and Place - Page 1
Forum section: electronics / repair

author: acastel
author_rank: Newbie
timestamp: October 15, 2025, 06:33:12 pm
content: I have a QUAD 2C pick and place. It performs the Quad Align initialization (if I remove the quad align board, it freezes), and it goes through the homing process. However, it performs the home on the X axis and then gets stuck at "HOME X", with no further response on the hand-held controller (Z and Y homing is OK).I also can't establish communication via the Central Controller (DOS VERSION - Communication with the MVS is working normally).Does anyone know what could be causing this?
Quad 303 amplifier won't power on - Page 1
Forum section: electronics / repair

author: reddish75
author_rank: Regular Contributor
timestamp: April 20, 2025, 12:46:01 pm
content: My Quad 303 won't switch on and I'm just checking I'm on the right track, checked dc at main caps and got nothingConfirmed 230vac to transformer,Disconnected transformer secondaries from bridge and got48vac8.1vacConnected them back and disconnected vdc from bridge rectifier and gotOn the vac 48v and 8.1von the vdc outputs on the bridge measures 2.5vdc on bothAm I looking at a shorted bridge or shorted transformer secondary?

author: tggzzz
author_rank: Super Contributor
timestamp: April 20, 2025, 01:32:34 pm
content: I presume you mean the 2.5Vdc is across the 2000F smoothing capacitors. What is the Vac reading across those capacitors, i.e. the ripple voltage?Visually examine all of the capacitors and nearby PCB, looking for leaks and case bulging.Consider a short across the DC power lines.Which bits are getting hot?Measure the voltage dropalongeach side of the PSU tracks. The more mV the higher the current.

author: DLJ
author_rank: Contributor
timestamp: April 20, 2025, 04:45:23 pm
content: I would check that the bridge rectifier hasn't gone open circuit.I doubt that you have a short circuit on the dc side as you would probably have checked the fuse, you haven't said that the fuse is OK but you have measured 48V ac voltage.

author: floobydust
author_rank: Super Contributor
timestamp: April 20, 2025, 05:10:40 pm
content: The 303 bridge rectifier is two pairs of stud-mount diodes (one pair common cathode, other common anode).They are mounted on two metal plates (+, -) then that on a phenolic strip, from what I can tell in pics.You can easily test each diode with a multimeter. These do seem to fail. Or look for an open connection.If a diode is shorted it should be blowing fuses. You can use a dim-bulb tester if you have too much trouble.*** When working on the amp, alway make sure the two 2,000uF filter caps are discharged, as well as the two 2,000uF output coupling caps. They store enough energy to damage things and make an unexpected spark.
Quad 303 Recapping Question - Page 1
Forum section: electronics / repair

author: postman56
author_rank: Newbie
timestamp: May 12, 2021, 01:02:28 pm
content: I'm not a experienced tech here, so bare with me.I want to replace the four larger power caps in my Quad 303 and they are all 2200 uF 100v DC.'s currently in there for from the manufacture.The Blue caps in my photos.I'm seeing Dada Electronics use the following in their upgrade package:• 1x 4700μF 100V capacitor for the power-supply• 2x 4700uF, 6800µF or 10.000µF 63V or 100V capacitors for the outputsAnd I'm seeing others use four 4700uF in both the power supply and the speaker outputs.I don't want to have to change any of the wiring connecting this to keep it simple but Dada recommends if using the 4700's as the upgrade the wiring needs to be a heavy gauge.Should I jut replace them all with the original values, only high quality capacitors?Any suggestions please would be welcome.

author: fcb
author_rank: Super Contributor
timestamp: May 12, 2021, 01:19:16 pm
content: From memory there is a 67V regulator circuit on the negative rail of the PSU. So I probably wouldn't go overboard with the PSU capacitance and risk the bridge recifier.Changing 2x2200uF for 1x4700uF should be fine.

author: Jay_Diddy_B
author_rank: Super Contributor
timestamp: May 12, 2021, 02:50:27 pm
content: Hi,I recapped my Quad 303 with 4x 4700uF. This is described in this message:https://www.eevblog.com/forum/repair/quad-303-power-amplifier-power-supply-repair/msg1223778/#msg1223778I used these parts from Digikey:They are still available and reasonably priced.I choose these parts to get a reasonable mechanical fit. The modern capacitors are small and metric. The originals are imperial dimensions. I increased the voltage and capacitance.The amplifier has worked fine since this repair.Best regards,Jay_Diddy_B
Quad 44 Oscillation - Page 1
Forum section: electronics / repair

author: reddish75
author_rank: Regular Contributor
timestamp: January 25, 2024, 06:25:59 am
content: I've followed the DaDa mods to this Quad 44 pre amp but have Oscillation on the output and am needing some hand holding as to narrowing this down to a particular circuit board at first.As it Oscillates on all inputs I though that I'd pop the old opamps back onto the Radio input card but still oscillation so input cards clear with that logic I think?This then leads me to the Mother board, where would I probe the signal? I was thinking along the lines of on attached pic,Points 3 inputs to the CD4066BE from the input cardsPoints F and A on IC403 for the output of this boardWhich points are the outputs of the IC SwitchesAttached Thumbnails

author: wasedadoc
author_rank: Super Contributor
timestamp: January 25, 2024, 02:18:22 pm
content: The points with a circled 3 are the sources' right inputs and points with a circled 5 are the sources' left inputs. The line with circled 2s is the right bus and is finally switched by the right most 4066 to the empty circle labelled 'OUTPUT-RIGHT'. Similarly for left bus circled 6s and 'OUTPUT-LEFT'.4066s are passive switches. No gain in them. They cannot oscillate.

author: MarkT
author_rank: Frequent Contributor
timestamp: January 25, 2024, 05:52:46 pm
content: Quote from: reddish75 on January 25, 2024, 06:25:59 amWell the suggested replacements require proper decoupling, TL071/072 are very tolerant of lax decoupling, so that might be a reason for oscillation - but what frequency is this oscillation?

author: floobydust
author_rank: Super Contributor
timestamp: January 25, 2024, 08:38:21 pm
content: OP tell us more about the mods you did. The DaDa site seems a bit off- the discontinued OPA604 replaced by OP07D? That seems wrong.There is mention of adding decoupling caps on the rails if things oscillate. That would show up in both channels.Quad 44 Service ManualorQUAD Manuals+diagrams 44
Quad feeder Schematic or other repair info? - Page 1
Forum section: electronics / repair

author: jmelson
author_rank: Super Contributor
timestamp: November 12, 2020, 03:39:15 am
content: Does anyone have schematics for Quad IQ feeders? I have one that worked a while ago, but now it just blinks LEDs but won't move when any button is pressed.Thanks,Jon
Quad FM4 fixup - Page 1
Forum section: electronics / repair

author: martinr33
author_rank: Frequent Contributor
timestamp: March 14, 2021, 04:11:13 am
content: I picked up a late model Quad FM4 tuner, non-functional. No display.1) The schematic has the microcontroller pins mislabeled. The schematic pins are labeled backwards. This can be confusing...2) Reconfigure for 110V operation. Odd that this was not already done. Display came back, but showing 150MHz.- the FM4 is clever - the display is a frequence counter right from the IF section, so what you see is the input frequency- uses a long-obsolete high speed ECL divide by 100 chip.3) Acid damage from a previous leak. The unit had a new NiMH Varta pin compatible battery installed.- replace all damaged components. Two diodes, one zener, a resistor and a 180 pF capacitor, plus the microcontroller socket- clean up PCB, remove all corrosion.3) Although not obvious, the damage had opened up the ground trace that feeds the tuner front end. So nothing worked until I bridged that.- Display now reads correctly but tuning range was off.4) Display was noisy, flickering up and down a few steps- went away after running overnight, presumably after charging the battery.Unit now seems very stable, locks in to stations and displays signal strength.Next up is audio testing.
Quadtech 7400 LCR meter external bias fail - Page 1
Forum section: electronics / repair

author: Electrole
author_rank: Contributor
timestamp: July 24, 2020, 08:35:50 pm
content: Hi, I have a Quadtech 7400 LCR meter which works very well, but with one exception: There's no connection from the external bias voltage input to the device under test. The voltage ends at the two pins where the external bias voltage enters the main board. The bias fuse on the back panel is OK. The internal bias function is OK (though the voltage is 1.85 V rather than the specified 2 V). I really suspect some relay malfunction, but before dismantling an otherwise well functioning piece of gear, I wonder if anybody should have the schematics for the 7400 available. It seems that there's nothing available out there on the 'net. A service manual with schematics would be just wonderful... If not, I think I will just have to take a closer look at a few relays...Best regards

author: coromonadalix
author_rank: Super Contributor
timestamp: July 24, 2020, 09:43:35 pm
content: Try asking the company if a service manual is available, or sign an non disclosure agreement ??
Quality control, or lack thereof... - Page 1
Forum section: electronics / repair

author: TheMG
author_rank: Frequent Contributor
timestamp: June 12, 2020, 11:40:43 pm
content: Thought some of you would find this interesting.First of all, soldering quality that looks like it was done by a 5th grader (actually, I'm pretty sure with a little practice, a 5th grader could do better). Yes, this power supply did let out the magic smoke, and I wouldn't be the least bit surprised if a dry solder joint caused it. "Dry as a dead dingo's donger" as Dave would put it!Secondly, the OEM for this power supply, U-San Electron Co Ltd, can't even spell their own name properly: U-SAN ECECTRON silkscreened on the PCB!Lastly, check out R16. It's a 2W resistor, not the flameproof type, across the 48V output (minimum load resistor). Color bands have changed color but it is indeed a 1k resistor. If we do the math, that's 2.3W of power dissipation. FAIL!!!! The placement of this resistor next to the output filter caps is also not a great design decision.The most surprising thing is, this is not a cheap consumer product at all, it is in fact enterprise level telco gear. Power supply for an HDSL (T1) line card cage. It's supposed to be high-reliability stuff.

author: Hornethandler
author_rank: Contributor
timestamp: June 13, 2020, 01:28:17 pm
content: Pretty scary looking soldering. I was a NASA quality inspector for electronic assembles and the workmanship on that board gives me the chills.If an operator turned in something like that for in-process or final inspection they would immediately be sent to a “re-education camp” for retraining and an attitude adjustment.

author: TimFox
author_rank: Super Contributor
timestamp: June 13, 2020, 03:53:18 pm
content: Perhaps you did not follow the instructions on the silk screen starting "FOR CONYINUED PROTECTINO..."

author: SeanB
author_rank: Super Contributor
timestamp: June 13, 2020, 07:43:17 pm
content: Probably an outsourced power supply, and the first batch worked as designed, so the manufacturer decided that they will cost optimise the design a little with each subsequent order, and thus some enterprising person figured out that simply by getting a cloned version made he could cut the cost by half in procuring it.
Question about display issue in HP 8590A Spectrum analyzer - Page 1
Forum section: electronics / repair

author: Johnny10
author_rank: Frequent Contributor
timestamp: March 07, 2021, 03:26:29 pm
content: I have been storing my HP8590A for about 4 months in a clean dry non-airconditioned space.Turning it on yesterday I was greeted with the first screen below. (screen is stable in this distortion not flickering)After a 2 hour turn-on time my screen was back to normal.This morning 12 hours later screen is again stable.What could be the issue?

author: bob91343
author_rank: Super Contributor
timestamp: March 07, 2021, 08:56:02 pm
content: Looks like a fault in the vertical amplifier. Perhaps a bad connection. I would open it and poke around with a screwdriver handle and see if I can make the problem come and go. Wiggle all the connectors.

author: m k
author_rank: Super Contributor
timestamp: March 09, 2021, 06:45:55 pm
content: Is it interlaced with dispositioned frames?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: March 09, 2021, 08:13:06 pm
content: Guessing dry electrolytics in the CRT circuit. Recap it.Or replace the module wholesale, it's a somewhat standard display module -- or it was at the time, don't know how cheap/available spares are now. I think some have even built LCD conversions, though the resolution is very nonstandard so it's a nontrivial process.Tim

author: MarkL
author_rank: Unknown
timestamp: March 09, 2021, 10:25:53 pm
content: There are different model monitors that HP used in the 859x series, but they should all have a vertical hold adjustment somewhere. At least one model has it accessible through a hole in the top of CRT case and I think is marked.Before doing anything drastic, I would try to find that pot first and give it a tap or a slight turn. If no joy, you could also try doing the same thing to the vertical height adjustment.
Question about finding replacement transistor - Page 1
Forum section: electronics / repair

author: Yamin
author_rank: Frequent Contributor
timestamp: January 31, 2022, 06:51:54 pm
content: I've got a generic power supply (output 12V, 20A) with a blown transistor. The transistor turned out to be a chinese made oneP13009The package is TO-3PB. I think it could be a MJE13009 knock off. But the package is different.I was wondering if I could replace them with a 2SC4140 since I have them in my parts bin.The ratings are similar from what I can see and some ratings are slightly higher than the faulty one.P13009:VCEO = 400VIC = 12A2SC4140:VCEO = 400VIC = 18A.These are the two main ratings I looked for, what more should I look for (in the future as well when I have to find equivalent replacements) and could I replace it? Also what is the significance of matching the package style apart from lead spacings?Thanks in advance.

author: abdulbadii
author_rank: Frequent Contributor
timestamp: January 31, 2022, 11:14:23 pm
content: As long as the replacement is greater, to mean better, than or equal to all the ratings of the replaced one it'd be fineinc. TcTamust be equal or higher than the ori.

author: rob77
author_rank: Super Contributor
timestamp: January 31, 2022, 11:29:06 pm
content: it's ok, but i would definitely replace both transistors on the primary side with the same type.
Question about how to fix a electrical issue on a obscure game controller - Page 1
Forum section: electronics / repair

author: reubenj
author_rank: Newbie
timestamp: January 18, 2022, 04:34:01 pm
content: https://www.reddit.com/r/SteamController/comments/s5v7l6/overheating_current_overdraw_on_steam_controller/An issue where the steam controller is overheating in the left grip. noticed over the last couple weeks that my controller has been draining batteries really fast but it was still working besides that. When plugged in a usb to the computer though (sans batteries) the SC LED starts rapidly flashing and input is unresponsive.According to the TPS61029 pdf (https://www.ti.com/lit/ds/symlink/tps61020.pdf) the IC accepts variable input, so if the regulator on the right [ TLV70230 ] (https://www.ti.com/product/TLV702) is failing, it may be feeding the TPS61029 too much voltage.Because it's a multi-layer pcb I can't tell which part comes first, the regulator or the boost converter, but if you can use a continuity test on the positive pin from the battery compartment you should be able to find out where that voltage hits first.According to the datasheet on the 3V regulator in the controller, it has an enable pin that when pulled high, turns on the regulator and I believe, the controller.https://www.ti.com/lit/ds/symlink/tlv702.pdf?ts=1642445860055Enable pin. Driving EN over 0.9 V turns on the regulator. Driving EN below 0.4 V puts the regulator into shutdown mode and reduces operating current to 1 μA, nominal. For TLV702P, output voltage is discharged through an internal 120-Ω resistor when device is shut downSo, if this part is failing it could be turning the device back on.If it's the regulator (TLV70230), then you can see what the output is, if it's higher than 3V, you know it's failed and it's a relatively easy fix. If not, it's more complicated I think.

author: reubenj
author_rank: Newbie
timestamp: January 18, 2022, 04:50:32 pm
content: Sorry that's a bit of a smash together of all the replies.Steam controller over heats on the left side, and auto turns on. They don't make them anymore so trying to keep what I have alive.
Question about oscilloscope probe grounding - Page 1
Forum section: electronics / repair

author: watchmaker
author_rank: Unknown
timestamp: June 25, 2025, 01:49:41 pm
content: I was given a 1960s marker generator for parts which I restoredThe setup shows Y channel cabled as expected; but the X cable is not to be grounded. (I am just running RF 316 for each channel from the 2 pin connector). I looked at the schematic, and this is consistent. The written description is also consistent. So, this is not a printing error.Given this is for use with a 1960s era service scope with a two prong plug.But, the potential for the horizontal signal has to be referenced to somewhere. And the shield grounding the vertical would seem to also ground the horizontal to the scope's ground.Why was this decision made? Does this have an impact for use on modern scopes?Interesting.

author: Harry_22
author_rank: Frequent Contributor
timestamp: June 29, 2025, 06:19:33 pm
content: Hi!Yes you are absolutely right, the potential for the horizontal sweep is also referenced to the ground. All scope inputs are referenced to ground (PE). The shield here is not required because X output has low resistance and thus low susceptibility to interference.This solution, if you mean using two axes X and Y, was made to replace the horizontal time axis of the oscilloscope with frequency. Thus you get the ability to see the amplitude-frequency response directly on oscilloscope screen.Modern oscilloscopes can also be used here. Only the horizontal sweep function is implemented in them programmatically from any channel input.My drawing below shows the load characteristic of one output lamp of Push-Pull cascade.To do this four signals were taken from the cascade: anode voltage, cathode voltage, and voltages from both sides of the second grid resistor. The load line itself as well as power lines were built according to programmed into the scope mathematical formulas in which the live input signals acted as variables.
question about soldering irons please help  - Page 1
Forum section: electronics / repair

author: Thabet
author_rank: Contributor
timestamp: October 07, 2024, 07:09:11 pm
content: hello guysis this a good soldiering iron ?https://vi.aliexpress.com/item/32803295956.html?gatewayAdapt=glo2vnmand in case its a good soldiering iron is this version good or you advice in another version ?and another question what is the best handle to get 907 or p9 or m8 metal ?and another question i see t12 c245 etc of tips what is the difference between them ?im asking about the t12 because a friend of mine suggested that for me but he work with mobile boards i don't i only do consoles , pc , gpu , laptops and im not sure that why i asked ?

author: ataradov
author_rank: Super Contributor
timestamp: October 07, 2024, 08:01:13 pm
content: This is a generic T12 soldering station. There are dozens of clones/variations. The overall design is generally fine with most of them, but build quality is pretty random as with any cheap Chinese product. I doubt you will find anyone with first hand experience with this exact version from this exact seller.C245 tip range has higher thermal mass tips, but both are fine for general repair work.

author: Thabet
author_rank: Contributor
timestamp: October 08, 2024, 03:19:16 am
content: Ty for the helpIs there any solder iron that you suggest me that isn't too expensive?

author: ataradov
author_rank: Super Contributor
timestamp: October 08, 2024, 04:51:36 am
content: Those T12 stations are good enough as far as inexpensive stations go. I can't suggest a specific seller, I have not bough one for a long time.

author: Thabet
author_rank: Contributor
timestamp: October 08, 2024, 05:58:16 am
content: No problem about the reseller what about that exact modle is it good or I need to get other modle cause from what I know some of them have some issues like grounding for example

author: ataradov
author_rank: Super Contributor
timestamp: October 08, 2024, 06:00:39 am
content: No idea, as I said, there are a ton of them out there and new ones pop up regularly. Who knows what's on the inside even if the label is the same.The best thing you can do is inspect it after you get one. Getting cheap stuff will always be a gamble.
Question about these two caps - Page 1
Forum section: electronics / repair

author: jayjr1105
author_rank: Regular Contributor
timestamp: July 03, 2020, 11:35:26 pm
content: I have a PSone that needs these two caps replaced to fix video issues. It's very common on this board. I ordered replacement SMD aluminum caps 220uf 6.3v and I already removed the old ones. They are reading normal around 220uf but ESR is well over 3 ohms. Is this why they are bad? Original's are 220uf 4v btw.

author: helius
author_rank: Super Contributor
timestamp: July 04, 2020, 12:08:37 am
content: At what test frequency was the ESR measured 3 ohms?I'm not familiar with that circuit, but as a guess, I'd say that they are coupling the output signal. High ESR in a coupling capacitor can lead to weak signal drive. Other problems could be (electrical) leakage, which would cause DC offset on the signal.

author: Bud
author_rank: Super Contributor
timestamp: July 04, 2020, 02:16:55 am
content: These SMD low profile electrolytic caps have high ESR in my experience, i mean higher than typical radial caps of same value, so 3 Ohm may be normal.
Question for users of the Metcal Talon tweezers.  - Page 1
Forum section: electronics / repair

author: gabinetex
author_rank: Newbie
timestamp: March 21, 2021, 05:40:24 pm
content: .

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: March 21, 2021, 05:50:31 pm
content: Sounds plausible - the power is divided between the 2 tips.However I found the Talon a waste of time - it's much quicker & easier to use 2 irons as you have much more control

author: Runco990
author_rank: Frequent Contributor
timestamp: March 21, 2021, 09:17:58 pm
content: Warm up time for the talon is normal. Also the de-solder hand piece takes about a minute.I have the Full MX-500 system and have repaired a few. It's my daily driver.The De-soldering gun requires a compressor/shop air. The Talon is kinda a waste... depends on the tips used. The trick to the talon is to use fresh solder and some flux on it before you try removing parts with it.It's a good system once you get used to HOW to use it.
QUESTION: Hakko FR-301 desolder tool.... what Mains Voltage? - Page 1
Forum section: electronics / repair

author: peteb2
author_rank: Regular Contributor
timestamp: January 26, 2020, 08:52:26 pm
content: I've searched as much as possible but can't find confirmation if the tool is completely multi-voltage (100Vac to 240Vac) or are they specified to a different Mains voltage use?I don't want to risk buying one online & end up it being no go for 230Vac (my local Mains). Thanks.

author: pigrew
author_rank: Frequent Contributor
timestamp: January 26, 2020, 09:06:24 pm
content: They supply different variants of product for different markets, so it is not all universal. The manual shows the PCB and heaters being differentThey sell 100-110V, 120V, 127V, 220-230V, and 240V versions. I'm not sure how the part numbers are different. I think the USA version is "FR-301-04/P".

author: Kwakerman
author_rank: Regular Contributor
timestamp: February 04, 2020, 02:57:30 pm
content: I have one supplied by Hakko UK for use in the UK and it is marked 230V 110W. 50Hz even though the UK mains is typically 240-245V, the UK's 230V is just a EU harmonisation thing, I think the UK it is actually specced at 230V -6 / +10% (rest of EU is +/- 6%) as the UKs distribution network and voltage didn't change in reality. Anyway the end result of that is that the label attached to mine for UK use gives the model number as FR301-22 if that helps.
Question on an AD549 Electrometer SCH - Page 1
Forum section: electronics / repair

author: BD1QMP
author_rank: Contributor
timestamp: January 06, 2024, 01:46:44 am
content: Recentely, I got a AD549 Electrometer PCB, maybe a pre-amplifier, after drawing the schematic, I cannot understand what is the purpose of the R49 1G oum resistor and how to us it. Any suggestion? thanks.

author: Sparks-Components
author_rank: Newbie
timestamp: January 06, 2024, 04:01:36 am
content: gives a fixed bias current to offset the input current of the amplifierOr circuit for internal calibration (IV conversion)
Question on metalized holes of multilayers PCB - Page 1
Forum section: electronics / repair

author: GGMM
author_rank: Frequent Contributor
timestamp: March 12, 2023, 08:28:51 am
content: Hello,Question on metalized holes of multilayer PCBs.May you confirm that a metal hole on a multilayer PCB is only a single connexion between 2 layers. (Where more, but it is the same "electrical" connection like on schématic?)Extreme example: if you have a pcb with 8 layers, you will never have extreme connection between layers 1-2,3-4,5-6,7-8. --->so 4 # connexions in only one hole.Which means that if you put a wire and weld it completely into this hole, you don’t change anything if it’s in good condition.I think you have understood my question.cdt

author: RoGeorge
author_rank: Super Contributor
timestamp: March 12, 2023, 08:45:53 am
content: If you fill a PCB hole with solder, you won't alter the already existing connection between layers, if that's your concern. It's safe to fill a metalized hole with solder.Metalisation covers the walls of the hole entirely, but only those layer that have to be connected together are bring in contact with the copper deposited inside the hole. The other copper layers (those that have to stay isolated from a hole's metalisation) are kept away from that hole, so they wont make electrical contact with the metalisation.

author: GGMM
author_rank: Frequent Contributor
timestamp: March 12, 2023, 10:22:16 am
content: Thanks for the answerIf we dig a little deeper, we see that it is a fairly complex process to metallize the holes.For your information:https://www.raypcb.com/6-main-processes-for-making-high-quality-pcb-plated-though-holes-pth/cdt
Question on Tekpower HY3010E short circuit protection? - Page 1
Forum section: electronics / repair

author: rfengg
author_rank: Regular Contributor
timestamp: November 25, 2023, 12:37:19 pm
content: Hi All,Procured a Tekpower HY3010E dc supply from Ebay which was sold as "working". The Tekpower HY3010E has inherent short circuit protection as per the manual.When I tried to set the current limit by applying a short at the output terminals, I cannot set a current limit of more than ~400mA.However, if I try to set a current limit of 1A using 4.7V output and 4.7ohms load, that works fine and I can set the limit to 1A.Is this normal behavior for a supply with "short circuit protection"? Do I have to use a load always rather than a short, to set the current limit?thanks.....

author: wn1fju
author_rank: Frequent Contributor
timestamp: November 26, 2023, 02:38:19 pm
content: I don't know if this applies to your power supply, but on many of my power supplies, if I short the output to set the current limit, I have to make sure that I have turned up the voltage a little. The voltage will then foldback to near zero and the current can be set through the short. If I don't do that, the power supply will basically sit idle with very little current (and voltage).

author: fmashockie
author_rank: Frequent Contributor
timestamp: November 26, 2023, 04:01:02 pm
content: Per the manual I found online for this supply (it wasn't much of a manual, but a user guide at best), to set the current limit, you bring the current setting all the way down with the fine and coarse current knobs. You then adjust the voltage fine and coarse knobs to the desired output voltage. Then you connect your load and bring the current knobs up to your desired current limit setting. This is a little bit different than other PSUs in that as another commenter mentioned, you usually short the negative/positive terminals to set the current limit.
Question on XHR100-10 - Page 1
Forum section: electronics / repair

author: VE7HR
author_rank: Contributor
timestamp: January 08, 2024, 03:46:22 am
content: I am testing out a XHR100-10 that has interesting issue. If you turn voltage control fully counterclockwise the voltage display shows 1.8V. Turning clockwise it goes to zero then continues to got to full scale. Fully CCW showing 1.8V is 0V output. Everything else approximately voltage meter on display plus 1.8V. So how does one shift that offset. I have yet to find answer in the manual. Also below 5V (6.8V) the supply makes a frying egg sound. I am hoping an expert can shed some light.ThanksDave

author: coromonadalix
author_rank: Super Contributor
timestamp: January 08, 2024, 04:21:17 am
content: svhttp://www.ko4bb.com/manuals/74.57.239.193/Xantrex_XHR_Xantrex_XHR_600W_1KW_Service_Manual_TM-XR01-XN.pdf

author: VE7HR
author_rank: Contributor
timestamp: January 11, 2024, 04:45:00 am
content: Thanks for the link to the manual. It’s the same copy I have. I must say a few words on how it works would have been is useful.The schematics have no hints on how it operates and does not give any details on what the various adjustment pots are for.Dave

author: coromonadalix
author_rank: Super Contributor
timestamp: January 11, 2024, 11:36:07 am
content: is it a model you got from a seller / something bought used ??on some psu you have some rear connector who need to be wired correctly for local use, voltage sensing etc ... sometimes they get removed and the psu is not working well unitl you make theses connectionhappened on my Kepco, thats why i got it cheaptheses psu are advanced, you have powerfactor correction, power control with mosfets etc ... 3 spms sections etc ...section 4 of the manual show this connector, at minimum you need to sense the output voltageas a last resort like i would do is find all the datasheet parts and application notes, and try to figure out how it could work,in this psu you have feedback lines who goes between the 3 main smps sections ....and figuring out how they work may or will be a pain without trouble shooting manual from Xantrex ...

author: VE7HR
author_rank: Contributor
timestamp: January 16, 2024, 05:37:12 am
content: I thought I replied that I got it used.It is now fixed.Turns out there was at least 1 cold solder joint on the board on one of the model specific resistors.Along the way I discovered that the VI check button was displaying the correct voltage which narrowed down where to look. At 3 times under the microscope one lead did not look quite right.So I fixed one cold solder joint. Is there more. ? Maybe. There I’d over 200 parts on the A3 board.On to fix next item on the pile.ThanksDave
Question re small capacitor markings - Page 1
Forum section: electronics / repair

author: niemand
author_rank: Contributor
timestamp: November 01, 2021, 01:33:08 am
content: I have two small canister capacitors with markings in three rows on the top as below:b1016No other markings observed.Do the markings tell me anything about the voltage and capacitance?Both capacitors have 3mm diam, 5.5mm height. Are these SMD capacitors, or do they have leads? I can't access the bottom side yet.Thanks.

author: xrunner
author_rank: Super Contributor
timestamp: November 01, 2021, 01:47:56 am
content: 10 uF16V

author: sleemanj
author_rank: Super Contributor
timestamp: November 01, 2021, 01:48:33 am
content: My assumption would be 10uF 16v and the b is probably some coding the manfacturer uses for some other parameter.
Question Regarding E4418B - Page 1
Forum section: electronics / repair

author: CrazyTiger
author_rank: Regular Contributor
timestamp: September 02, 2021, 03:25:39 am
content: I bought a E4418B from ebay recently, it was stated dead/no display, I figured it was likely a power supply problem. ( I was wrong)Once I received it, power up the unit, the LCD was flickering but nothing.Opening up the unit, i found the horror, some idiot tried repairing the units motherboard, it was a terrible job, the IC's were installed crooked, the lithium battery had an "upgrade" to support CR2032 Battery, all the FETs had one leg lifted off.The "upgrade"First thing i rectified all the solder joints, and replaced the crooked logic ICs and op-amps to new one.Then turned ON the unit, still i had only LCD flickering, going further in, I found the SRAM was dead, after replacing it, the unit spring back to life.Now I have a question, never had a E4418B before, in the system info menu, its stating E4418A and I noticed my unit have a LAN port, but I dont see anywhere where to set the IP, is this because the unit is seeing itself as "A" Unit? If yes how do I set back the unit to be a "B" model.I see i can set the serial number, will do that after new battery arrives, not sure if the serial number plays a role in instrument identification.

author: testpoint1
author_rank: Frequent Contributor
timestamp: September 02, 2021, 03:53:21 am
content: please check the firmware chip sticker, the 4418B version is different as 4418A.

author: CrazyTiger
author_rank: Regular Contributor
timestamp: September 02, 2021, 07:21:12 am
content: The flash chip indicates:E4418 80020 ad 80019 (High and Low), And U14 is labelled e4418 80022. Did not see any other label.Did I end up with a canablized unit, with E4418A motherboard on a E4418b body?

author: CrazyTiger
author_rank: Regular Contributor
timestamp: September 02, 2021, 07:55:40 am
content: Problem solved, it was something to do with an old Agilent Circular, since i notice i could not find a section on the power meter to configure serial port as well, i started to look for that solution, where I came across a circular by Agilent.Here is the note:http://literature.cdn.keysight.com/litweb/pdf/E4418B-09.pdfThe moment I set the processor version, the unit detected as E4418B and Serial Port Settings were available, Now I have a fully working E4418BRemark: Turns Out E4418B does not have a Ethernet/Lan capability, but they used a RJ-45 Connector as a TTL Output, I mistook the port as LXI enabled unit

author: View[+]Finder
author_rank: Unknown
timestamp: March 11, 2023, 11:49:03 pm
content: https://support.keysight.com/KeysightdCX/s/knowledge-article-detail?language=en_US&keyid=How-do-I-restore-missing-RS-232-interface-soft-key-and-functionality-on-legacy-EPM-E4418B-and-E4419B-power-metersThat is the current link to restore functionality of E4418B
Question/Help with Original Xbox Clock Capacitor replacement option. - Page 1
Forum section: electronics / repair

author: mictas
author_rank: Regular Contributor
timestamp: April 28, 2020, 10:37:25 am
content: Hello all,Well, I have two of these floating around, that will not keep time and while I have not opened either xbox, someone else has.What I would like to do is order the replacement clock capacitors, before I go opening anything up and see what damage is or has been done.With that, the one I have found is on RShttps://au.rs-online.com/web/p/electric-double-layer-capacitors/7637860/I was hoping someone with experience with swapping out these capacitors could tell me if this would work?Thank you in advanced.
Quick 861DW Repair - Page 1
Forum section: electronics / repair

author: drauzinho
author_rank: Newbie
timestamp: May 10, 2020, 05:09:02 pm
content: Hi guys, as a matter of fact, I forgot my station was 110V and powered it from 220V, it was just for a couple of minutes and everything was fine, but as I turned it off, it never turned on again. I checked the fuse, and it didn't blow, but it just doesn't turn on anymore. Does anyone could help me as what I should check, and what is probably blown ? I looked at the PCB, and everything looks ok.Thanks a lot.

author: wraper
author_rank: Unknown
timestamp: May 10, 2020, 05:21:51 pm
content: First check power input resistance with power switch in ON position to see if transformer primary did not fail open and check and if there are output voltages from transformer.
Quick fix for DC electronic load? - Page 1
Forum section: electronics / repair

author: crashintoty
author_rank: Newbie
timestamp: March 02, 2020, 03:23:10 am
content: I picked up a new Kunkin KL283 DC dual channel electronic load device (https://www.ebay.com/itm/30A-Dual-Channel-DC-Electronic-Load-Adjustable-digital-LED-display-KL283-Adapter/371958986412). Channel 2 of this device works just fine, but for some reason channel 1 always shows a voltage of 2.56 despite no power source or leads connected to it. If I attached any power source to it (battery or bench power supply) channel 1 then reads 156.08 volts no matter what the actual voltage of the source (3.2, 3.7, 5, 12, 24, etc. volts). Turning on a load does nothing - the voltage doesn't change from 156.08.Returning/exchanging this would mean a week or more turn around, but I don't want to wait that long. I'm not an expert, but I'm very comfortable tinkering with/fixing electronics - based on the description of the problem can you suggest any quick fixes or diagnostic methods for troubleshooting the mysterious voltage readings on channel 1 and getting it to work/properly draw current?

author: TheMG
author_rank: Frequent Contributor
timestamp: March 03, 2020, 02:10:39 am
content: Since you always get the exact same two voltage numbers, I would suspect a fault somewhere in the digital realm. Could be a defective ADC or bad communication between the MCU and ADC.You could confirm this by measuring the voltage that is present at the ADC input pin for that channel, and see if it varies according to the load voltage.
Quicko T12 STM32 pinout diagram required. - Page 1
Forum section: electronics / repair

author: ntj77
author_rank: Newbie
timestamp: March 01, 2021, 09:54:23 am
content: Hi All,I purchased a Quicko T12 STM32 soldering iron controller from AliExpress and the iron handle was not included in the selection (by mistake). So I purchased an iron handle with cable and relalized that I made another mistake. The Quicko controller has a 6 pin connector, where as the iron handle has 5 pin connector. I have figured out the connections of the handle and can rewire it to suit the controller but I'm still not able to figure out the pinout connection of the 6C connector. Can someone please help me with this?

author: PKTKS
author_rank: Super Contributor
timestamp: March 01, 2021, 10:27:13 am
content: You will probably have to ask them or figure it out...I have seen 4 and 5 pin models.. not 6 so far..Attached some stuff collected since then...Paul
Quiet Noctua Fans for Keithley 2002 and 2001 - Not advised. - Page 1
Forum section: electronics / repair

author: pamphonica
author_rank: Regular Contributor
timestamp: February 19, 2024, 08:08:02 pm
content: I have contemplated for a while quieting my Keithley 2001 and 2002 by using Noctua fans, which are often recommended for their low noise and good performance. A re-cap of both DMMs re-opened the fan debate.I checked the specs for the existing Elina fans and the Noctua NF-A4x10 fan I have used elesewhere. The worrying thing was the airflow, at only 65% of the original. The Noctua is a slim 10mm fan and the Elina is a 12mm fan. There is absolutely no room for a thicker fan as the pcb pretty much butts against the fanTest time. I rigged up a minute RTD PT100 sensor on fine wires inside my K2001 and let it run for 15 hours, first with the original fan, then the Noctua fan.The results were conclusive. The existing (rather noisy) fan keep the interior at about 38 degC. The incredibly quiet Noctua only manages to keep it at 48 degC.That's not a good result so I won't be using the Noctua fans as replacements. It's not worth trying the test with the K2002 - I'll just put up with the fan noise.Interestingly, the K2002 has a different airflow internally, compared to the K2001. It uses the same plastic cover over the analogue board but the K2002 adds a clear plastic guide to put all the air through a hole into the inside of the cover. The K2001 has no guide and no hole in the cover so all the air goes round the outside. Presumably in the K2002 it is more important to keep the 8.5 digit analogue electronics happy than the power supply regulators etc!-Jeremy

author: SeanB
author_rank: Super Contributor
timestamp: February 19, 2024, 09:10:14 pm
content: Noisy fan often will be quiet again with some surgery to add oil to the bearing in the fan. Easy to do with a peel of the label, and a insulin syringe to add 0.2ml of 5W synthetic oil into the bushing cavity, then put the cap back.

author: J-R
author_rank: Super Contributor
timestamp: February 19, 2024, 11:22:32 pm
content: Try a single 20mm fan outside the chassis or two fans in series, one inside, one outside:https://noctua.at/en/axial-fans-in-series-or-parallel-operation
QX-7277A sound board - Page 1
Forum section: electronics / repair

author: owanneke
author_rank: Newbie
timestamp: May 15, 2020, 08:39:03 pm
content: My kid has a toy car he can drive in with sound effects.For some reason the sounds play way fast since today.There's 4 sound buttons.Left, right, horn and music.If you press music and keep the contact shorted, it plays at normal speed.Yet given you have shorted a button, you cannot play any other sound after.i've tried dropping the input voltage, but without succes; either it stays fast or it doesn't play at all.Not sure if that's because this cannot fix it or because I need a really specific R value to make it work.Measured all Rs and Cs, seem fine.Any advice would be welcome, it has sentimental value.https://imgur.com/a/jE7xSVS

author: Manul
author_rank: Super Contributor
timestamp: May 15, 2020, 09:08:25 pm
content: Well, I suggest to desolder wires, take it on a bench, clean good with alcohol and observe really good. Maybe just try to reflow every component with solder, there is not a lot of them. Of course, do not overheat. This board has buttons, so it means it is flexing. Flexing may cause solder micro cracks which is hard to see without microscope.If you are confident with soldering, just reflow everything, can not hurt.

author: owanneke
author_rank: Newbie
timestamp: May 16, 2020, 09:46:28 am
content: Totally nailed that.Resoldered the wires and components by hand, stopped working all together.Reflowed in the kitchen oven, 200C 10 minutes, came out crispy brown, warped and the whole house smells like burnt electronics.No sound.Anyone know where I could get such a replacement board?
R1224N332H Replacement - Page 1
Forum section: electronics / repair

author: protonq
author_rank: Newbie
timestamp: June 01, 2024, 11:41:00 pm
content: Hi all. I'm trying to repair an audio interface that doesn't power on. The chip U30 gets very hot so I suspect it's shorted. Here'a link to the chip:https://www.mouser.com/ProductDetail/Nisshinbo/R1224N332H-TR-FE?qs=ilL34mSzaLj7X9jgTohRLw%3D%3DThe problem is I cannot find that particular chip available anywhere in small quantity. If anyone can suggest a compatible replacement I'd appreciate it.Attached are images of the board and schematic.Thanks in advance for any insight.