hybridfree/eevblog-posts huggingface dataset:
AMM Simpson 260 doesn't look at all like repair videos or docs. - Page 1
Forum section: electronics / repair

author: ballsystemlord
author_rank: Frequent Contributor
timestamp: June 20, 2023, 03:34:25 am
content: Hello,I'm trying to repair a Simpson 260 AMM. It's a hand-me-down from my late grandfather who was an EE. The AMM accepts 5 batteries, 4 AA and one D cell. It suffers from corrosion damage. Unfortunately, all the repair docs and videos I've been able to dig up on this model show it having a PCB for all the components whereas mine looks like the components are embedded into the bakelite.My need is to remove the bluish buildup after the AA batteries that my Grandfather placed into it leaked. So far, I managed to get a lot of the corrosion off with just a dremel and a straight SS brush attachment.The camera will not focus, but you can see inside the blue reflecting from deep inside of the AMM. And my dremel will not fit into that area.Additionally, one of the battery negative terminals has become frozen as a result of exposure to the acid. If you know how to free it up, I would appreciate the advise. I intended to just leave it the way that it is and use a small conductive aluminum piece as a spacer, to hold the AA cell in place.Any ideas how to get the corrosion off so that this AMM will work?Thanks!PS: I removed all the screws and nuts I can see, but the bakelite piece will not budge and I am unwilling to force it.PPS: I can post larger pictures if you want bigger ones.

author: ballsystemlord
author_rank: Frequent Contributor
timestamp: June 20, 2023, 11:52:11 pm
content: Just a thought, could it be that this meter is a pre-production model or something? It's hand scored, series #13 and I know my Grandfather had access to a lot of pre-production equipment from a variety of manufacturers.

author: mzacharias
author_rank: Frequent Contributor
timestamp: June 21, 2023, 12:41:43 pm
content: Looks like a 260 Series 2 to me.Go to simpson260.com for manuals, etc. For some reason the page takes forever to load. Be patient.

author: ballsystemlord
author_rank: Frequent Contributor
timestamp: June 22, 2023, 12:24:27 am
content: That's the one, thanks!I'll post updates as I get it repaired.

author: AUBI
author_rank: Newbie
timestamp: July 18, 2023, 07:54:49 am
content: For removing rust, you may need this kind brush:https://www.aubibrush.com/mini-hand-scratch-knife-brush

author: Runco990
author_rank: Frequent Contributor
timestamp: July 18, 2023, 03:39:45 pm
content: Use white Vinegar to remove battery corrosion safely, rinse well.

author: Stray Electron
author_rank: Super Contributor
timestamp: July 19, 2023, 01:48:45 am
content: Quote from: Runco990 on July 18, 2023, 03:39:45 pmCLR and LimeAway also work well for taking off battery corrosion.
Ampeg PF-500 Main MOSFET question - Page 1
Forum section: electronics / repair

author: Stuggi
author_rank: Newbie
timestamp: September 29, 2022, 08:02:23 pm
content: I got my hands on a bass amplifier, a PF-500 which seems to be a Class D 500W amp. However, it has an issue that the PSU part of it starts, and then resets probably due to overcurrent, dropping the main caps down, restarting the switchmode power supply again, which produces a 1 Hz ticking sound on the output. I traced the issue to a blown MOSFET on the speaker output, which according to the scematic should be an IRFB4227, however the amp is fitted with a pair of FDP33N25, which according to my eyes seems to be a much punier FET. The board also had a ceramic cap/resistor in series fitted between drain and source on both MOSFETs, a bodge that isn't on the 2009 schematic at least.So, should I go with the IRFBs or the FDPs? Any idea what the bodge is for? Schematic attached for your viewing pleasure, it's Q10 and Q11.

author: Stuggi
author_rank: Newbie
timestamp: September 30, 2022, 08:38:57 pm
content: I tore into the bodges, and it's a 1000pF ceramic capacitor in series with a 10 ohm / 1 Watt resistor. Some sort of snubber?

author: Vicus
author_rank: Regular Contributor
timestamp: October 03, 2022, 10:26:59 pm
content: For shure a snubber. It looks like the 33n25 is easier to drive. To me replace with what they use in OM.

author: Stuggi
author_rank: Newbie
timestamp: October 11, 2022, 01:12:49 pm
content: Well, it turned out to be a bit of a theoretical question, as the 33N25 was essentially the only MOSFET in that ballpark that I could get my hands on. The new FETS did however fix it, which was nice!

author: Vicus
author_rank: Regular Contributor
timestamp: November 02, 2022, 05:40:04 pm
content: It happen that the blown mosfet is not the only faulty component.
Amplifier Op Amp - Page 1
Forum section: electronics / repair

author: jheatac
author_rank: Regular Contributor
timestamp: June 27, 2024, 02:41:25 am
content: I am looking at a car audio amplifier.I seem to have all the appropriate power rails but am not getting an audio signal through the unit.In looking at U5 (U5 on board) (U5B on schematic) I get a signal to it, but not from it. I have +12 and -12. R80, R187 and R188 seem close enough to spec.My scope is acting up so I am sending a 1khz signal in and following it through with an audio tracer. The input side of R18 stays at 1khz. When power is applied, the U5 side of R18 sounds like a capacitor is charging as the unit comes on and then the signal is lost.Could it be a faulty capacitor around U5? Is U5 faulty? or is something down the line from "radio" back feeding or loading the circuit?If it were through hole, I would remove and check the capacitors. I am less adept with surface mount.

author: Circlotron
author_rank: Super Contributor
timestamp: June 27, 2024, 02:48:27 am
content: You won't measure any reasonable amount of signal at pin 6 of the opamp because it is a virtual ground point. Whenever the signal from R18 goes positive for example, the feedback signal from R80 goes negative by just enough to *almost* completely counteract R18 signal. The entire open loop gain of the opamp gets into action to make this happen. Because the open loop gain is very very high, the size of the signal at pin 6 isextremelysmall. So if your opamp has an open loop gain of 1 million and has an output of 1V rms then pin 6 will have a signal of 1uV.

author: magic
author_rank: Super Contributor
timestamp: June 27, 2024, 05:14:13 am
content: Check if the ±12V power supplies to the chip are OK.Check if the DC on both pins 5,6 is GND.Check if there is no short from pin 7 to pin 6.Check if the "radio" node isn't shorted.Check continuity of solder joints.

author: Audiorepair
author_rank: Frequent Contributor
timestamp: June 27, 2024, 08:29:12 am
content: If U5 were faulty it would almost certainly have DC on its output pin 7.You should be able to easily measure this with a mutllimeter.This is assuming it has the correct power supplies on pins 4 & 8.
Amplifier Research 75A250A - Help With Repair - Page 1
Forum section: electronics / repair

author: Bruno123
author_rank: Newbie
timestamp: October 22, 2019, 12:11:38 pm
content: Hello,I'm trying to repair an Amplifier Research model 75A250A, as I detected a short circuit in the input circuit. It is a 75 W 10kHz - 250 MHz amplifier.The overvoltage/surge protecion device CR2 (no marking code), the device AT1 (marking code 06) and U2 (marking code H346 - voltage-variable attenuator from analog devices) seem to be all short-circuited.I couldn't identify CR2 nor AT1 (seems to be an attenuator). Does anyone have the service manual/schematics for this amplifier or have an ideia about what these devices could be? The input is rated at 1mW.

author: fzabkar
author_rank: Super Contributor
timestamp: October 23, 2019, 05:48:29 am
content: The absolute maximum RF Input Power for U2 is +18 dBm, and its RF1 pin is DC coupled and matched to 50 Ohm.https://www.analog.com/media/en/technical-documentation/data-sheets/hmc346ms8g.pdfDoes this suggest a suitable candidate for CR2? I'm thinking that it must consist of two diodes connected in antiparallel in order to clip both positive and negative signal excursions.As for AT1, perhaps you could get some idea of its internal makeup by measuring U3 ("03") at the output of U2.Edit: Could ATI and U3 be pi-section filters? (1 x series inductor plus a grounded capacitor at each end)Edit #2: The amp's input rating would suggest that a BAT15-04W Series silicon RF Schottky diode pair might be suitable for CR2. ICBW, though.www.testequipmenthq.com/datasheets/AMPLIFIER%20RESEARCH-75A250A-Datasheet.pdfQuotehttps://www.infineon.com/dgdl/Infineon-BAT15-04W-DS-v01_00-EN.pdf?fileId=5546d46265f064ff016638961e2b4e86
Amprobe 37XR-A "2.Err" - Page 1
Forum section: electronics / repair

author: brunomp
author_rank: Newbie
timestamp: February 10, 2023, 10:38:49 am
content: I have one multimeter with this error "2.Err"i dont know what this meancan anyone help?thanks

author: shakalnokturn
author_rank: Super Contributor
timestamp: February 10, 2023, 08:55:50 pm
content: I do not know what it means.Does it display that whatever the function or only on current?These meters have dual contacts on some of the input sockets to detect if the leads are correctly plugged for the selected function ?It could be worth cleaning the input sockets.Some DMM's also detect blown fuses, have you checked fuses?Other than that I'd check the function selector switch contacts, dirty contacts can give unexpected behaviour i.e. when the CPU is being told one function but the input path is selecting something different.A similar post:https://www.eevblog.com/forum/testgear/really-odd-meterman-37xr-problem/

author: brunomp
author_rank: Newbie
timestamp: February 13, 2023, 09:25:04 am
content: thanks for your repply.Does it display that whatever the function or only on current? yes its only on current.These meters have dual contacts on some of the input sockets to detect if the leads are correctly plugged for the selected function ? Yes this multimeter detect if the probe test is on the right position.Some DMM's also detect blown fuses, have you checked fuses? The fuses its OK.I have clean the contacts but, it's the same.

author: brunomp
author_rank: Newbie
timestamp: March 21, 2023, 11:20:10 am
content: Hello,after much research and experimentation. I managed to discover the origin of the error, it is the corrupted flash.I changed it and it was OK.Thank you for your help.

author: shakalnokturn
author_rank: Super Contributor
timestamp: March 21, 2023, 09:59:02 pm
content: Flash as in microprocessor's firmware or configuration EEPROM?How did you go about replacing and rewriting necessary data?

author: brunomp
author_rank: Newbie
timestamp: March 22, 2023, 11:47:15 am
content: Hello,the flash is AT93C46D(x8)@SOIC8_37XR_OK. i read the another multimeter.
Amprobe 570 capacitance not working  - Page 1
Forum section: electronics / repair

author: BrianR
author_rank: Newbie
timestamp: November 17, 2024, 04:49:39 am
content: I just joined here to get some assistance with a possible repair. My amprobe has stopped working when testing capacitance. I called fluke/amprobe but they say it’s not an actively supported product and can’t help. Basically, throw it out and get a fluke.But it’s in great shape and everything seems to be OK except for this issue. Is there any recommendation on how to troubleshoot this?Thanks!
AMPROBE HA-2000 Power Quality Analyzer  - Page 1
Forum section: electronics / repair

author: kawal
author_rank: Frequent Contributor
timestamp: January 31, 2023, 06:57:15 pm
content: Bought one of these broken to fix and use testing AC power. I could not find any information about these so I will include what I know.The unit must have been designed in the1990s based on Firmware 1.01 from 1994.The unit came as promised not working. There was some battery corrosion in the battery box but nothing major.The inside is a mix of SMD uPC and through hole on everything else.There is a battery backup that supplies power to a static RAM. This battery was found to have only 200mV so no way it could provide any backup but the manual mentions the life of the battery is about 11 years so no surprise its dead after 30.After inspecting the unit and reading the firmware I proceeded to power the unit from a power supply . The meter would turn on the back light and consume about 185mA but the screen would just flash for a moment and show nothing.My thought was that the micro must be working as the display seems to refresh and disappear.After some messing around I went for the user manual. It turns out the software starts the screen with no contrast. this can be adjusted by pressing the enter / arrow keys together. That brought the screen back to life.Mechanically these seem to have issues with the buttons. There was a meter retention ring holding the buttons in place. After years these retention rings just fall out and they seem to also crack the plastic around the buttons.I designed a plastic button retention unit that fits on the remaining plastic and adds supports that brace against the PCB board.Now waiting on a battery holder to replace the soldered in 2032 backup battery.Voltage measures in line with my modern multi meters. Harmonic display is very interesting. Seems there is 5% of harmonic content in my house.

author: kawal
author_rank: Frequent Contributor
timestamp: January 31, 2023, 07:03:04 pm
content: here is the firmware and a few other pictures.
(SOLVED)Amprobe HD160C DMM---  Looking for the service manual. - Page 1
Forum section: electronics / repair

author: Paceguy
author_rank: Regular Contributor
timestamp: April 30, 2024, 06:20:43 pm
content: I have two Amprobe HD160C's to repair. One show ERR on AC function, and the other shows open on C & F temp ranges even with thermocouple connected. Does anyone know where I can find the service manual and schematics? I found the operators manaul online, but there is no service info there. Thanks in advance!

author: Kosmic
author_rank: Super Contributor
timestamp: April 30, 2024, 06:35:19 pm
content: Quote from: Paceguy on April 30, 2024, 06:20:43 pmI asked Amprobe for the service manual for the HD160B recently (for the calibration and adjustments procedure), but no response yet

author: Paceguy
author_rank: Regular Contributor
timestamp: April 30, 2024, 08:17:58 pm
content: Me too, I sent them an email about purchasing those small screws and battery compartment gasket for the HD160C. No answer. Not surprised, they are part of Fluke now. Fluke also is not too good at supporting their older products. It's kind of dishartening to see a major test equipment company treat the owners of their products in such a manner, really makes one think twice about buying their products in the future.

author: Kosmic
author_rank: Super Contributor
timestamp: May 01, 2024, 12:48:15 am
content: I wonder if Fluke tech support has any documentation on those meters ? since it look like they are absorbing Amprobe.

author: Kosmic
author_rank: Super Contributor
timestamp: May 01, 2024, 02:27:00 pm
content: @Paceguy send your request to info@amprobe.com. Got someone from Fluke answering this morning.

author: Kosmic
author_rank: Super Contributor
timestamp: May 02, 2024, 03:14:32 pm
content: They sent me the calibration procedure for the HD160C. The document mention "1.Err" and "2.Err" being related to bad calibration of a particular mode.

author: Paceguy
author_rank: Regular Contributor
timestamp: May 03, 2024, 10:57:05 am
content: Thank You Kosmic, I will go thru the entire cal proceedure, it could be out of cal according to the final note, since it's 1Err that I'm getting on the AC setting and 3Err was first showing on the current ranges. Thanks again!

author: Paceguy
author_rank: Regular Contributor
timestamp: May 04, 2024, 10:25:13 am
content: Thanks again Kosmic. To anyone who have Amprob HD160C's that display error codes 1 & 2. Proper calibration resolves the problem. I calibrated one of the ones that I have and all is good now.
Amprobe HD160C parts needed. No support from Amprobe. - Page 1
Forum section: electronics / repair

author: Paceguy
author_rank: Regular Contributor
timestamp: June 22, 2024, 04:58:29 pm
content: Hi,Does anyone know where I can find and purchase the casing screws and battery compartment rubber gasket/seal for my 2 Amprobe HD160C multimeters?
Amprobe Meterman 30XR Issue - Help Me - Page 1
Forum section: electronics / repair

author: Suhail79
author_rank: Newbie
timestamp: April 07, 2023, 02:27:41 pm
content: Dear EEVblogI have Amprobe Meterman 30XR which have an issue, it’s gives ALL the readings (-OL) whatever I select it shows me the same (-OL) readingDid anyone faced an issue like this or know how to fix this issueThanks a lot

author: Suhail79
author_rank: Newbie
timestamp: April 11, 2023, 12:12:29 am
content: Hello guysAny help

author: coromonadalix
author_rank: Super Contributor
timestamp: April 11, 2023, 02:00:46 pm
content: pls be patient, no need to ask many timesIf someone can help you may receive some answer ...

author: J-R
author_rank: Super Contributor
timestamp: April 11, 2023, 08:59:39 pm
content: You should take it apart and inspect everything. Post high resolution photos of anything that looks suspicious.
AMREL DC electronic load - Page 1
Forum section: electronics / repair

author: Nevada
author_rank: Contributor
timestamp: June 23, 2023, 10:12:50 am
content: Hi,I got an AMREL PELS DC electronic load, which has a weird problem: there is strange (random) characters on the LCD. There is an "Installing" phase after power on, but it looks the program is corrupted. There is a Dallas DS1643 RAM in it, but it is not clear for me, a single replacement could be solve the problem. I already ordered a new RAM from China/eBay (ST M48T18-150PC1), but it did not solve the problem (but there is no guarantee that these new RAMs are not fake ones....)Is there anybody here who is familiar whith these units? Unfortunately I couldn't find any service manual for it.
AMREL FEL 150-2 150W Electronic Load - display not showing actual current - Page 1
Forum section: electronics / repair

author: mkz
author_rank: Newbie
timestamp: December 18, 2021, 05:47:32 pm
content: Hi AllAnyone have access to circuit diagrams for this old unit?Picked it up on ebay - powers up fine, but current always shows 0.000A on the display - even when I have a test current shown as 1.5A via a multimeter in series with the load.thanks

author: ReedTriesToRepair
author_rank: Contributor
timestamp: January 27, 2024, 11:18:07 pm
content: Did you ever figure out the cause of issue, or find any documentation on your load? I believe I'm experiencing a similar issue. I can't even find the manual for it online...
AMREL LPS 302 - Page 1
Forum section: electronics / repair

author: Hrvoje_CRO
author_rank: Regular Contributor
timestamp: September 14, 2025, 10:55:06 am
content: Hello!I have purchased from ebay Amrel's Linear Power Supply LPS 302 which gives me out by default 5.000V.@0.300AOn LCD it is simbol which indicates "lo rng", so my general question is: how to enter into "hi rng"?Thank you in advance!

author: shabaz
author_rank: Frequent Contributor
timestamp: September 14, 2025, 11:35:55 am
content: There's aPDF user guideit's buried toward the end at section 3.7 that the indicator is not user-controlled, the PSU should switch by itself between the modes (presumably according to the set voltage, i.e. switching to the high current mode when the programmed voltage is less than 15V, but perhaps it depends on set current limit too).
AMREL / MOTECH LPS-305 Bench Power Supply Replacement Binding posts Restauration - Page 1
Forum section: electronics / repair

author: Fractal
author_rank: Contributor
timestamp: January 27, 2022, 12:43:55 pm
content: Hi!So I just got me this linear 3ch power supply for a great price locally here in Taiwan; about $55 yankees and of course it's a second hand unit, but it pretty beat itMost noticeably the binding posts look like they've been chewed on by some very physics class averse high schoolersIt's all functional apart from that, everything else looks good, just a bit of dust and yellowing I don't mind dealing with, but those posts need to go.Any idea where I could find suitable replacement? They're pretty oddly dimensioned and the manufacturer is also long goneAny help appreciated!Cheers!

author: Fractal
author_rank: Contributor
timestamp: January 27, 2022, 03:43:00 pm
content: Okay so I figured I would look further into finding more about the manufacturer,Shows up both Motech and Amrel still exist, the former having moved on to solar power systems while the latter freakin military hardware hahaI know it's a long shot, sent a mail to both, now we wait.

author: tooki
author_rank: Super Contributor
timestamp: January 27, 2022, 06:07:31 pm
content: Does it matter that theylookidentical? What do you think is “odd” about the dimensions? Because it’s certainly not hard to find binding posts that will fit the existing 8mm holes, like Keystone 7004, Cal-Test CT2232, Pomona 3760, Cliff TP2, Ritel 24 15 xx xx, and many, many, many others. Which of those is appropriate depends on how the rotation keying is done (some are flattened on one side, some on two sides, some use a thing that sticks out).

author: Fractal
author_rank: Contributor
timestamp: January 31, 2022, 08:56:09 am
content: Yoo quick update and happy conclusion,Well what were the odds; I happened to find exactly the same spec replacements at my local electronics shop!Just grey instead of beige, which ends up looking neater yet IMOOnly $17 taiwan $, about .60 yankees a popWent in with a little cleaningNotice the almost fully autorouted pcbAnd she's good as new!

author: tooki
author_rank: Super Contributor
timestamp: January 31, 2022, 01:53:01 pm
content: Well it's a really common style of binding post, so I'm actually not super surprised!Nice job, though, the end result looks perfect!
Amstrad PCW let out the magic smoke! (CRT Board Repair) - Page 1
Forum section: electronics / repair

author: BlueApple
author_rank: Regular Contributor
timestamp: August 30, 2022, 09:43:56 pm
content: I found an Amstrad PCW 8256 at an estate sale. When I got it home and powered it on smoke came out. Looking at the board one capacitor is bulging. There also is no power on the 12v rail.Can capacitors let out smoke without it being visible?

author: Rasz
author_rank: Super Contributor
timestamp: September 02, 2022, 05:31:07 pm
content: to amateur eye? definitely

author: BlueApple
author_rank: Regular Contributor
timestamp: September 02, 2022, 06:55:36 pm
content: Quote from: Rasz on September 02, 2022, 05:31:07 pmOk. I'm gonna go ahead and buy a new cap.

author: Rasz
author_rank: Super Contributor
timestamp: September 02, 2022, 07:32:17 pm
content: singular cap? so you did find the culprit? afaik there are a couple of electrolytics on pcw

author: BlueApple
author_rank: Regular Contributor
timestamp: September 02, 2022, 07:38:42 pm
content: Only the one cap is bulging and tests bad with my multimeter. I just desoldered it to test it out of circuit and it still tests bad. It was leaking too.

author: BlueApple
author_rank: Regular Contributor
timestamp: October 08, 2022, 07:08:17 pm
content: I replaced that cap, turned it on, and a few transistors blew up.

author: Rasz
author_rank: Super Contributor
timestamp: October 08, 2022, 08:37:46 pm
content: haha thats awesome!looking athttps://www.cpcwiki.eu/index.php/PCW_Mainboard_Versions#PCW_8256.2F8512I dont see any transistorsis there a rifa capacitor in the power supply?

author: Audiorepair
author_rank: Frequent Contributor
timestamp: October 08, 2022, 08:38:34 pm
content: I think prisoners should be given such tasks whilst incarcerated.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: October 08, 2022, 11:51:51 pm
content: Quote from: Audiorepair on October 08, 2022, 08:38:34 pmWhat? Vaping electrolytics?Tim

author: Gyro
author_rank: Super Contributor
timestamp: October 09, 2022, 01:26:42 pm
content: Quote from: BlueApple on October 08, 2022, 07:08:17 pmQuote from: Rasz on October 08, 2022, 08:37:46 pmIt seems likely that the 'transistors' may actually be Tantalum bead capacitors. Those are what I would expect to blow up in a noticable fashion on something that old that has been stored in unknown conditions.

author: BlueApple
author_rank: Regular Contributor
timestamp: October 10, 2022, 02:48:06 pm
content: Quote from: Gyro on October 09, 2022, 01:26:42 pmDo they have 3 legs? And also they are on the power board not the computer board.

author: BlueApple
author_rank: Regular Contributor
timestamp: November 16, 2022, 07:38:34 pm
content: I figured out why the transistors blew up, I forgot to connect the power to the motherboard and they must've overloaded.
An Electric shock from a new adjustable soldering iron - Page 1
Forum section: electronics / repair

author: Dhanushka
author_rank: Regular Contributor
timestamp: August 22, 2019, 07:37:15 pm
content: Dear all,I have brought this soldering iron. I got an electric shock after a one day. The voltage between metal part and home ground about 45 V/AC. But changing live wire to the neutral that was eliminated. There was no continuity between metal parts and live or neutral wires. Mains is 230 V/AC and it has two prong plug. Is this normal? How can I solve this?Thank you.

author: magic
author_rank: Super Contributor
timestamp: August 22, 2019, 07:49:19 pm
content: Don't turn it on, take it apart

author: TimFox
author_rank: Super Contributor
timestamp: August 22, 2019, 08:35:28 pm
content: If connected to 100 to 120 VAC, this is typical for a capacitor network at the line, with no “PE” ground connection to the exposed metal. Are you running with a two-prong outlet and an adapter, with no third-wire ground?

author: Dhanushka
author_rank: Regular Contributor
timestamp: August 23, 2019, 04:02:52 am
content: The mains is 230 V/AC and this has EU two prong plug.

author: TimFox
author_rank: Super Contributor
timestamp: August 23, 2019, 04:24:30 pm
content: Then, to be safe, it needs to be double-insulated. However, if it uses a temperature servo with switching from the line, it should have an EMC filter and that raises the grounding question.

author: David Hess
author_rank: Super Contributor
timestamp: August 23, 2019, 05:22:45 pm
content: That is normal for a two prong device where the neutral is swapped with hot. High impedance multimeter measurements can be deceptive because of capacitive coupling.

author: Mechatrommer
author_rank: Super Contributor
timestamp: August 23, 2019, 06:05:15 pm
content: 1st 2 pictures is the circuit, before the ground wire mod (cable changed to 3 prong). the next pictures is mod suggestion, (heat shrink tube, spring for easy contact needed) make sure ground wire insulator will not get burnt by the heat and hence possibly get shorted with offline circuitry. so ensure your house's GFCI/RCCB is working properly. i used normal wire in the pic because i dont have heat resistance rubber wire.
An electrolytic cap with 5.5V and.... 0.047µF?! (Solved, it's a supercap) - Page 1
Forum section: electronics / repair

author: klausman
author_rank: Regular Contributor
timestamp: April 17, 2025, 09:20:46 am
content: Solved: it's a supercap: it's not 0.047µF, but 0.047F!, so 47mF. The Service Manual makes itreallyeasy to miss the F vs µF in the parts list. Once I searched for NEC FYD, it became clearAnd they're still sold, though by KEMET, not NEC.So I am repairing a Marantz PM-62 and I am swapping some of the caps that are out of spec. This particular cap I haven't tested yet, but seeing its specs made me double-take. I was not aware electrolytic aluminium cans went that low in capacitance. The Service Manual lists it as CU08 on the PU01 board, Marantz No. 482212423128, and the same values as printed on the device.From the schematic, it seems like it's just filtering power supply voltage for the IC to its left (QU01, a TMP47C200BN 4bit microcontroller). The device itself is unusually squat (~11mm across, ~8mm high):Out of curiosity I tried to find one of these on Digikey, but the laughably low capacitance isn't even listed.So what are these for? And where would I find one if I needed it?I've also attached the SM in case the above snippet of the schematic is not enough

author: picburner
author_rank: Frequent Contributor
timestamp: April 17, 2025, 09:30:04 am
content: It is a so called supercap and the capacity is expressed in Farad.It acts as a small battery, probably the IC next to it has to store some data temporarily.

author: valcher
author_rank: Contributor
timestamp: April 17, 2025, 09:44:07 am
content: Interestingly, the designation of the values ​​in this diagram for resistors corresponds to all the designation rules, but the capacitors are designated only by numbers.So guess.

author: klausman
author_rank: Regular Contributor
timestamp: April 17, 2025, 09:50:27 am
content: QuoteWell, at least the parts list in the SM does say µF, nF, pF etc for the other caps and just F for this one. But as I said, it's very easy to miss.

author: coromonadalix
author_rank: Super Contributor
timestamp: April 17, 2025, 12:10:59 pm
content: yeah its an 0.047 farad or 47000 uf and for sure it's confusing if you dont go in the sm part list description ...but in those times, a supercap most of the time was green, now any color or metallic casing, i see more blue ones ...

author: timeandfrequency
author_rank: Frequent Contributor
timestamp: April 17, 2025, 02:33:19 pm
content: Quote from: coromonadalix on April 17, 2025, 12:10:59 pmAnd also somewhite parts.But those are 'Ultracaps'...

author: amyk
author_rank: Super Contributor
timestamp: April 18, 2025, 08:06:46 am
content: 0.047uF (very rarely) exists for electrolytics, but with much higher voltage ratings.Someone else on the Internet made the same mistake:https://www.tedss.com/2020070006?srsltid=AfmBOooeMEj-xT4-66YSHnAwubRAiSzcf87I9DC49vOfUilc7ur3YEBY
Anadex Frequency Synthesizer FS-600 docs wanted - Page 1
Forum section: electronics / repair

author: Old Goat
author_rank: Contributor
timestamp: February 10, 2021, 06:34:05 pm
content: I have an excellently constructed synth, the Anadex FS-600, and it could use some TLC. I've not found ANY docs for it ANYwhere, so am asking here, perhaps someone worldwide recognizes it and has docs/schematics for it?Thanks for looking whether you have what I'm looking for or not.Old Goat

author: 8alonzo8
author_rank: Newbie
timestamp: March 01, 2021, 10:46:30 pm
content: I am new to this forum and I have the same issue. I have looked everywhere for any information on this frequency synthesizer and cannot find anything. Please let me know if you were able to locate anything.Thanks

author: Old Goat
author_rank: Contributor
timestamp: May 26, 2021, 02:00:07 pm
content: No, I've found nothing. I was able to "walk in" the output frequency by comparing internal osc to my 10mhz GPS receiver output. So that was close enough for my purposes.
Analog multimeter fault repair Ohms - Page 1
Forum section: electronics / repair

author: cleanworkbench
author_rank: Regular Contributor
timestamp: January 25, 2024, 02:37:08 pm
content: I have a analog multimeter 30 years old now and it has developed a fault . On X10K range it is fully adjustable to beyond zero ie the right hand side , but on ranges X1K, X10 and X1 it can only be adjusted up to 2/3 two thirds of FSD ?. On all other functions it works perfectly , does anyone have any suggestions to where i can start to repair this weird fault please.There is no sign of damage inside the case ie the circuitry .

author: Kleinstein
author_rank: Super Contributor
timestamp: January 25, 2024, 03:06:46 pm
content: A frist point would be to check if the batteries are still OK. Old dry cells (non alkaline) can be to weak tot deliver the required current.The protection with the old meters often was not that good - so a damage to some internal resistors is possible.The old meters were a bit different in how the realized the resistance functions. It could help to know the meter type and if a vailable get a schematics.Are the other functions working ? Parts can also be shared with the current ranges.

author: wasedadoc
author_rank: Super Contributor
timestamp: January 25, 2024, 05:48:36 pm
content: Yes, check the battery. Some meters had two different batteries. A higher voltage one for the highest resistance range.
Analog multimeter range problem - Page 1
Forum section: electronics / repair

author: NiaDebesis
author_rank: Frequent Contributor
timestamp: April 01, 2021, 05:57:55 pm
content: Hi guys,recently I found 2 Goerz Unigor 6E in the dumpster.The first one had a little problem with the VDC, was a few mV off, but since I have a Fluke dc standard was no problem.The second one is a little bit more complicated, this multimeter on the bottom has a switch to select different types of measurement (+ , R - , C ~)Ideally when switching from this three ranges my needle should remain at 0, but in this case it changes quite a bit, circa 5 divisions per scale (It goues up and down) only in the C ~ range it remains at zero.I thought that this could be a capacitor problem, is it possible?If someone had a similar experience please let me know

author: bob91343
author_rank: Super Contributor
timestamp: April 01, 2021, 06:44:27 pm
content: Do you have a manual and/or schematic diagram?

author: NiaDebesis
author_rank: Frequent Contributor
timestamp: April 02, 2021, 10:23:35 am
content: No unfortunally

author: coromonadalix
author_rank: Super Contributor
timestamp: April 02, 2021, 10:57:29 am
content: https://elektrotanya.com/unigor_6e_6ep_multimeter_sm.pdf/download.html#dlthere was a thread here : just pushed the same linkhttps://www.eevblog.com/forum/testgear/resuerrecting-unigor-6e/

author: NiaDebesis
author_rank: Frequent Contributor
timestamp: April 04, 2021, 07:43:14 pm
content: Quote from: coromonadalix on April 02, 2021, 10:57:29 amI have removed all the old caps, I only left the ones with good ESR.And I noticed that the movement now works flawlessy but it does have problems with the r and c scales, probably because there are some missing caps, because 1 or two where not decoupling or filtering caps only.I'll take new caps this week so I hope it will work!I have gathered a Unigor 1e in the meanthime lol
Analog scope won't auto trigger anymore after sitting unused for a few month - Page 1
Forum section: electronics / repair

author: Noxy
author_rank: Newbie
timestamp: May 03, 2020, 09:05:13 pm
content: As a novice, I've got myself an old analog oscope to experiment (basically just to fry that instead of the digital one I already own).It's a cheap entry level advanced/gould OS1000A which was working just fine when I first got it but today, after sitting unused for a few months, the AUTO trigger doesn't work anymore.In details, when the trig level is adjusted within the range of the input signal it trigger just fine, otherwise the screen goes blank as it would in normal mode.Instead, if I set the trig knob to free run, it free run as usual.Repairing an oscilloscope is definitely out of range for my level but this one is a relatively simple model and also the issue doesn't seem too complex.How is the free run behaviour obtained in an analog oscilloscope?Of course the beam is swept across the screen at a certain frequency but where is such signal taken from? Is it usually generated by dedicated circuitry on the trigger board or it's derived from other sources?Either ways, since I can get the oscilloscope to trigger and free run by working on the controls, is safe to assume that both circuits are working fine, isn't it?Perhaps the issue isn't far from the trigger knob.What do you guys think ?

author: CaptDon
author_rank: Super Contributor
timestamp: May 04, 2020, 02:22:59 am
content: Sometimes there is a free running oscillator that is gated on or offby the trigger circuits. If no trigger is sensed the free running oscillatoris allowed to start running and it will trigger the sweep. It is injectedafter the trigger sensing circuits so that the scope won't think it hasa 'valid' trigger. Some scopes have a sort of slide bias on the sweeposcillator, If no valid trigger is detected the 'triggered sweep oscillator'will begin to have its stability slide toward 'free run'. When a validtrigger becomes present the bias will shift back to 'gate on triggeronly'. The time constant of the slide bias is usually about 1 secondwhich is why you have to select 'normal mode' if you are viewing atrigger source which only occurs at two second intervals or longer.The scope would revert to 'auto' and start sweeping and not be readyfor a valid trigger to sync properly.
analogic 2045 waveform synthesizers firmware - Page 1
Forum section: electronics / repair

author: jclab
author_rank: Newbie
timestamp: May 14, 2024, 01:00:28 am
content: hello.i am from korea.recentry, i bought a analogic 2045 waveform synthesizer which is not working in vfd display.after many time analysis about vfd display, finaly i success enableling the display. i repaired 74ls series ic( 74ls05, 74ls11, 74ls393) that make a problem in vfd bais voltage. after that, there is another problem. the display stucked at "self test progress" and there is no message" press any key". i think maybe there are any problem in firmware. so next process is not doing. anyone help for firmware update? i cannot find any repair manual, and firmware about analogic 2045. please sent me a firmware about analogic 2045.

author: NyquistNoise
author_rank: Contributor
timestamp: June 14, 2025, 07:33:29 pm
content: I've attached a copy of my EEPROM files in .bin format. Hope they helpBR

author: jclab
author_rank: Newbie
timestamp: July 06, 2025, 11:50:36 pm
content: thank you for your help.i found the root cause of the fail.there is some fault at osscillater on mainboard.so i replaced the osscillater, and my equipment operate well.
ANALYST 3Q LEM NETWORK ANALYZER SOFTWARE - PQLOGVIEW - Page 1
Forum section: electronics / repair

author: EDER
author_rank: Contributor
timestamp: October 18, 2024, 03:53:38 am
content: Good evening dear community, I would be grateful if you could share with me the software of the LEM network analyzer model ANALYST 3Q, according to what is indicated in the user manual it is the PQLogView, here I show you the photo of the equipment. In case we can reach an agreement for its marketing/sale, I remain attentive.I thank you in advance for your attention.

author: Simon
author_rank: Unknown
timestamp: October 18, 2024, 01:11:45 pm
content: Please don't double post. It winds people up and they complain.
Anbernic RG353M no sound and linux not bootable  - Page 1
Forum section: electronics / repair

author: Saeniv
author_rank: Newbie
timestamp: February 27, 2025, 02:41:46 pm
content: Hello,I read a lot through other issues and the ArkOS wiki and reddit, but I can't solve my issue. My RG353M has no sound in the android mode, so i upgraded to android firmware, but did not solve my problem, so i wanted to install ArkOS. One time the sound worked on a youtube video, but only once. The headphone jack kind of works with a lot of noise.I flashed the RG353M ArkOS and the handheld won't boot, the screen stays black and the green led is shining, with a short interrupt of a red light, nothing else happens. I tried 3 different SD Cards, I tried Rufus and Win32 Image Tool, I tried different OSes like UnofficalOS, ROCKNIX and the official Linux version from your anbernicWith none of my attempts, I were able to boot, always the same picture, black screen green light. I fully charged the console and also left the power cord attached.So i opened it up and supplied it via a lab power supply. I measured the VCC from the Power Managment Chip to the CPU, which shows that during the Android mode, the voltage is very stable and the system has no problem to boot, only the sound is missing.When I insert an SD card with a freshly flashed ArkOS, the system won't boot and the VCC voltage has very short 30ns spikes from 780mV up to 1V. The recommended voltage range reach from 810mV to 900mV.I supplied +3.3V to the sd card slot, just in case the PMC has problem with that, which he don't becuase i was able to upgrade the Android via the same sd card slot.Did anyone repair such a device or has any ideas?

author: Saeniv
author_rank: Newbie
timestamp: February 27, 2025, 02:44:14 pm
content: Datasheets of the RK3566 and the Power Managment Chip RK817-5

author: Saeniv
author_rank: Newbie
timestamp: March 04, 2025, 10:59:56 am
content: I upgraded the output capcitors of the RK817-5 buck converter from 22µF to 33µF wich solved the unstable supply voltage to the CPU, but it is still not booting with the Linux SD card and I have no sound under android.The RG353M is basically the Radxa CM3 just in a different form factor, documentation can be found on the internet. I am currently reading through the Radxa forum but have not a valuable solution.
And another Tek 465B with DM44 meter issue. - Page 1
Forum section: electronics / repair

author: JohnTinkers
author_rank: Contributor
timestamp: June 27, 2025, 03:17:35 pm
content: Hi -- working on my Tek 465B with DM44. The meter has dancing numbers. In intensity mode, I do see the Delta-Time cursor, but the numbers don't appear to make sense. Followed the troubleshooting flowchart, and replaced U3211, which is a LM 339 comparator. I also replaced U3023, which is a LM324 Op-Amp. That seemed to help for a little bit, but when the scope is cold, it dances badly.The voltage between GND2 and TP3167 is NOT stable.The power supply inbound voltages are +5=+4.98, +12=+12.08, -12=-12.08. from the power lead when pulled off the DM44 board. These are completely stable.Ohms, volts and temp are in the ballpark, but they dance within a narrow range. A calibrate is needed, and that will be tackled as soon as I get the display stabilized.If the meter is left on for 1 hour or so, the dancing slows but it does not stop. Thermal issue?The schematic is somewhat cryptic. It's difficult to trace this for me; but I am trying.I just noticed! If I switch modes and or ranges, I get intermittent blinking and intermittent negative signs. Suspecting the switch array. Is it ok to hit these with Deoxit D5? I know that you cannot let Deoxit near the volts/div and Delay time cams or the attenuators, but I think that the previous IPA cleaning was incomplete.I think that this something minor, but I am trying to see where the problem lies. I thank you guys for any pointers you might offer.ThanksJohn.

author: Testtech
author_rank: Regular Contributor
timestamp: June 28, 2025, 10:22:09 pm
content: You can clean any of the push button switches with Deoxit no problem.

author: ME
author_rank: Frequent Contributor
timestamp: June 29, 2025, 10:41:23 am
content: If i remember the ic sockets were made by TI and were well known to go bad on these!.

author: JohnTinkers
author_rank: Contributor
timestamp: July 02, 2025, 03:59:58 pm
content: Quote from: ME on June 29, 2025, 10:41:23 amThanks for the reminder! I remember seeing that on ZenWizard Studio on YouTube. The 339s are on those bad TI sockets, while the ADC are on those discrete socket pins. Perhaps I will pop the board and replace with known good sockets. I have PDIP 14 and 16 sockets in stock.

author: JohnTinkers
author_rank: Contributor
timestamp: July 07, 2025, 01:19:34 am
content: Quote from: ME on June 29, 2025, 10:41:23 amI took your advice. The most likely candidate to help was the socketed 16 pin U3340, which is a LD110CJ that I paid US$57 to replace. 🤬. It’s part of the ADC circuit.So I pulled out the socket and replaced it with a nice DIP socket.Wow!While not 100% stable it is much more stable. Better still, the unit seemed to snap into excellent calibration and the volts and ohms match my modern 5 1/2 digit bench multimeter with minimal cal.BTW I hit all the push buttons with deoxit D5 hard and worked the buttons and let the DM44 board dry overnight. But the socket replacement is what did the trick.I consider this a success and I have you to thank for it. Thanks!!
ANDO AQ6330 repair (optical spectrum analyzer) - Page 1
Forum section: electronics / repair

author: tititoto
author_rank: Newbie
timestamp: December 05, 2023, 11:11:23 am
content: Hi,we own an old ANDO AQ6330 that most of the time did'nt start up and sometimes startup.When it does'nt start, even the bios doesn't show up, no beep are heard.PSU boad was checked and all power rails looks good (I may miss one as I did'nt have a schematic...).IR camera doesn't reveal a component failure so far.This device use a EPSON 486-CARD running a windows OS, a kind of old school Raspberry pi!Bios, PROC, RAM are on board. There is a ISA port, PS/2, MOUSE, VGA, SERIAL, PARALELLE ports.Here's the manual of this CARD:https://download.epson-europe.com/pub/electronics-de/card-pc/486/486hm-e.pdfI did following measure:-check lithium batt: 3V OK-SCLK:8.XMHz OK (means POWERGOOD)-SUSSTAT#: 5V-BATLOW: 5V-PWRGOOD: 4.8V-VBK: 5V-EXTSMI: 5V-SRBTN: 5V-RESETDRV: alternance low/high: cyclic reset of bus.Any idea to test??Sincerely,
Andonstar microscope screen fades to white - power issue? - Page 1
Forum section: electronics / repair

author: ThingWizard
author_rank: Contributor
timestamp: July 25, 2021, 06:16:14 pm
content: This is a bit of a there's a hole in the bucket problem. So my issue is with my Andonstar AD207 "microscope" that I bought for SMD soldering. Sometimes (it's an intermittent error) after running fine for about half a minute the screen starts going white in the corners and then after about 10-20 seconds the whole screen "implodes" - that is fades in on itself towards the middle. The resulting color is something greyish. A reboot usually helps.I have tried using another usb power cable directly to the screen from a charger, instead of using the power lead from the same on-cord controller that is used to distribute power to the screen as well as to the lamps. With a separate power source the screen is much better but can show some fading in the corners from time to time.it's as if the screen looses its pixel driving power. Could this be caused by a failing capacitor?I found this youtube video of a guy who had the same issue on his desktop monitor, this is more or less exactly what happens to my screen too:(I don't have to smack mine...)Just curious as to what this might be and if it can be fixed.
android iptv box - Page 1
Forum section: electronics / repair

author: login
author_rank: Contributor
timestamp: March 06, 2018, 10:08:42 pm
content: here's a long shot but has anybody tried to repair an android iptv box? Mine fails to power up. There is no fuse, power seems to be straight into an smd cap. I measure a short through the first few caps after the dc input socket and would like to change them but being surface mount they have no markings to indicate their value. The box is branded MII box model A9. What I would like is a circuit diagram but I doubt they exist or info if someone else has been down the same path. Any help appreciated.

author: denimdragon
author_rank: Regular Contributor
timestamp: March 06, 2018, 10:26:15 pm
content: Can you take a pic of the PCB area and post it? It might helpful if we can see what you see

author: Shock
author_rank: Super Contributor
timestamp: March 08, 2018, 01:26:18 am
content: Are you sure they are caps and the short is across the caps?What kind of short is it and how did you find it? Did you notice device sinking too much current or do a diode test in both directions across the supply rails, or do a resistance test in both directions? You should take (and show) measurements if you are unsure.If they are caps and causing a dead short across the supply rails that shouldn't prevent you from confirming the device is working after the offender is removed. If they are just used for a bit of supply filtering the device will operate without them especially when testing with your own bench supply (current limited).As for working out what capacitors, you can deduce it by the surrounding components such as two capacitors in parallel can be the same values. A capacitor next to a regulator could be a nominal value shown in the regulators datasheet or found in comparable circuits.

author: Shonky
author_rank: Frequent Contributor
timestamp: October 06, 2023, 11:32:52 am
content: Bot/AI post reportedFor OP there's pretty much no chance you'll get a schematic. Post a pic and tell us you can measure. I'd more likely expect corrupted/bad firmware

author: Halcyon
author_rank: Unknown
timestamp: October 06, 2023, 12:32:30 pm
content: Quote from: Shonky on October 06, 2023, 11:32:52 amDeleted/banned. Thanks for the report.