hybridfree/eevblog-posts huggingface dataset:
Nicolet 2090 III digital scope need basic set help or manual. - Page 1
Forum section: electronics / testgear

author: wd5jfr
author_rank: Regular Contributor
timestamp: December 06, 2021, 04:13:15 pm
content: Just picked up a nice very, very clean one (from 1978?) and Variaced it on and seems to work except that I can't set it to display a trace but I see random pattern of dots, nice bright display with numerics. All the different settings I've tried won't make a trace.In the PEN Function I see the spot moving up the left side of the crt then partially across the top of the screen and down.I hope it's just a problem with the basic set up and if anyone can guide me I'd sure like to see if I can get a trace and some other functions if it's operational. On reflection I think it might be the vertical section but I hope it's my ignorance on set up.ThanksHank

author: tunk
author_rank: Super Contributor
timestamp: December 06, 2021, 05:08:00 pm
content: Wouldn't really know and probably doesn't make any difference,if you assume lower left is channel B, and you've set channel A as trigger.

author: wd5jfr
author_rank: Regular Contributor
timestamp: December 06, 2021, 06:09:34 pm
content: Thanks for looking and you are correct on both points and and figured someone would catch something.Here's a proper setting pic.

author: Andrew_Debbie
author_rank: Frequent Contributor
timestamp: December 06, 2021, 09:17:29 pm
content: Amazing that it still works. I briefly used a Nicolet Med-80 and did a little programming on one around 1984. It was a few years old and waay out of date -- It was a 20-bit machine with core memory. The display was in a Tek 5000 series mainframe. There was an 8" floppy and it also had a paper tape reader. Most programs were on paper tape.It was an odd thing - partly hardwired like a DSO and partly programmable like an old mini computer.It did DSO stuff but mostly was used as a signal averager. The A/D module had 'scope like controls and a 50kHz sampling rate. It could also play Pong. Knobs on the Med-80 moved the paddles. Display was on the Tektronix 'scope.

author: wd5jfr
author_rank: Regular Contributor
timestamp: December 07, 2021, 10:16:19 pm
content: Got a couple of more traces from trial and error settings. If you look closely at the dim display you can see the peaks of a squished sine wave. I hope it's a setup problem but I still think;s related to the input. Still hoping for help.

author: wd5jfr
author_rank: Regular Contributor
timestamp: December 09, 2021, 03:59:31 am
content: Here's some specs:https://testequipmentconnection.com/specs/NIC%202090%20SPECS.PDF

author: shakalnokturn
author_rank: Super Contributor
timestamp: December 09, 2021, 10:07:35 pm
content: Does it trigger at all?

author: wd5jfr
author_rank: Regular Contributor
timestamp: December 09, 2021, 10:38:34 pm
content: Yes, the trigger light flashes but I don't see anything after the flash on the crt. Sometime the trigger light will stay until I move a control but it seems to be different ones each time.

author: wd5jfr
author_rank: Regular Contributor
timestamp: December 26, 2021, 10:46:42 pm
content: Still looking for help.ThanksHan
Soviet standard resistors? - Page 1
Forum section: electronics / testgear

author: dmmguy
author_rank: Contributor
timestamp: December 24, 2021, 07:05:27 pm
content: Hi there...How they performs?https://www.ebay.com/itm/271930151419Thanks

author: alm
author_rank: Super Contributor
timestamp: December 24, 2021, 10:31:48 pm
content: There are some comments within the first 26 posts here:https://www.eevblog.com/forum/metrology/teardown-standard-resistors/. Seems quality is somewhat variable.User HighVoltage seems to like them.

author: dmmguy
author_rank: Contributor
timestamp: December 25, 2021, 12:15:55 am
content: Quote from: alm on December 24, 2021, 10:31:48 pmI couldn't fine anything on the first link to posted. The second one has some references. Thank you so much!

author: alm
author_rank: Super Contributor
timestamp: December 25, 2021, 12:26:32 am
content: Look more closely:Quote from: manganin on March 10, 2016, 12:43:49 pmQuote from: manganin on March 10, 2016, 02:42:59 pmQuote from: zlymex on March 10, 2016, 04:07:54 pm
Aliexpress returns are now literally as easy as Amazon! - Page 1
Forum section: electronics / testgear

author: Fungus
author_rank: Super Contributor
timestamp: December 24, 2021, 05:00:22 pm
content: Not 100% testgear related I know, but... I figure a lot of people here would be interested.I just ordered something on Aliexpress that turned out to be nothing like the photo so I decided to open a dispute.I was directed to a 'returns' page to download a PDF shipping label. I slapped it on the packet, walked 100 yards to a shop near here and handed it over. The guy scanned the barcode and put it in a big bag. Job done. No charge.I'm in a city in Spain. I dunno if it's the same where you live but if this is the new returns system then I'll be buying bigger stuff on Aliexpress.(I've only bought one thing over $50 on Aliexpress so far - my little Uni-T thermal camera)

author: Caliaxy
author_rank: Frequent Contributor
timestamp: December 24, 2021, 06:25:38 pm
content: Was the return address in China, or Europe?

author: floobydust
author_rank: Super Contributor
timestamp: December 24, 2021, 07:13:33 pm
content: I've had the same Aliexpress easy return experience - put the defective item in a box, print the label and drop it off at any of a handful of mysterious shipping firms including Joy Luck Grocery storeIt seems the chinese have just bypassed local post and other inefficient, expensive shipping firms. They are setting up shop and aggregating their way.The return address was to the port in Canada, not to china. It's likely not worth shipping back? The item ad said "return shipping guaranteed".

author: Fungus
author_rank: Super Contributor
timestamp: December 24, 2021, 07:33:24 pm
content: Quote from: Caliaxy on December 24, 2021, 06:25:38 pmEurope (Barcelona)I'm guessing they'll put them all in container that's on the way back to China.

author: Fungus
author_rank: Super Contributor
timestamp: December 24, 2021, 07:35:13 pm
content: Quote from: floobydust on December 24, 2021, 07:13:33 pmOne of the places near me was a pet food store.(but it was closed - I guess they didn't feel like opening on Xmas eve)

author: Fungus
author_rank: Super Contributor
timestamp: December 24, 2021, 09:41:12 pm
content: Quote from: evb149 on December 24, 2021, 08:46:20 pmNo American would ever do that, amiright?

author: nigelwright7557
author_rank: Frequent Contributor
timestamp: December 24, 2021, 10:40:47 pm
content: I bought some 5mm pitch capacitors from Ali Express.When they came they were 7.5mm so wouldnt fit my pcb.Before they would refund me they wanted pictures of capacitor next to a ruler to show discrepancy.Some of the Ali Express stuff is very cheap.I was using AD9202 a2d converters from RS for £10.I found them for $1.50 at Ali Express ! and they worked !
Finally figured out how to get rid of the interference of my desk LED lamp - Page 1
Forum section: electronics / testgear

author: bayjelly
author_rank: Regular Contributor
timestamp: December 27, 2021, 06:11:26 am
content: So I've had this "PHIVE" desk LED lamp for a while. I like it, but the problem that I always had with it was that it generates so strong interference that I often had to turn it off when using the scope, which is extremely annoying obviously.Seriously bad, I'm talking ~500mV p-to-p spikes when the ground lead is connected to the spoke tip, enough for false triggers even from low impedance sources. Setting the scope to 20MHz bandwidth limiting would help, but of course that's no way to live.So I thought, maybe not the lamp itself but the power supply is the problem, and connected the lamp to my (linear) lab supply instead. With good news and bad news.The bad news is that the interference is exactly the same with the lab supply, so it's generated in the lamp itself (hence ferrite cores also did nothing). The good news is... it goes awaycompletely, and I meanentirely, once the voltage fed is below ~9.5V. The power supply it came with is 12V. But above around 9.4V, the interference suddenly kicks in in full strength. It's binary: Either quiet at low voltage or fully kicking at higher voltage.I know nothing about strong LED lighting, my guess is that below 9.5V the current to the LED is constant, and above it it's switching? Anyway, I ordered a 9.3V power supply from eBay and it looks like I can now keep the lights on when using my scope.Maybe that helps someone else with similar problems.

author: tooki
author_rank: Super Contributor
timestamp: December 27, 2021, 04:42:21 pm
content: My guess is that it uses a buck converter with an output of around 9.5V (3 LEDs in series are right around that voltage), and that below that, the converter simply doesn't switch at all.
Brymen 869s - Voltage Input limits and Duty Cycle measurements - Page 1
Forum section: electronics / testgear

author: brock
author_rank: Newbie
timestamp: December 22, 2021, 10:59:33 pm
content: Hello EEVblog folks,I have a Brymen 869s and I used it to measure the duty cycle of a 208 VAC sine wave signal, which I plan to modulate with a dimmer circuit.My question is, would the meter be damaged if there was a 208 VAC signal present on the meter's inputs, while the meter is set to the DCmV or Duty% function? I was able to measure the 50% duty of the signal before modulating it. No signs of damage and no burnt smells. I was only a bit worried when saw the battery icon flashing. The manual doesn't state what causes that but I wonder if this is an indication of a fault, damage or simply telling me that I was using the wrong scale/range.It seems like this function is intended to be used on low voltage circuits based on what the manual states: " Range: 0.1% to 99.99% / Accuracy: ± (3 digits/kHz + 2 digits) / Input Frequency: 5Hz -- 500 kHz, 5V Logic Family". Still, I would like to know if the specified "Input Impedance: 10M, 60pF nominal (80pF nominal for 500mV range)" still applies and protects the meter while in this function.Any thoughts?Thanks for reading,Brock

author: Fungus
author_rank: Super Contributor
timestamp: December 22, 2021, 11:27:03 pm
content: The meter is protected to 1000V on those ranges so no damage should occur.OTOH The frequency ranges are designed for 5V logic so it's probably a good idea to pass the signal through a voltage divider first. That way you won't be triggering the meter's protection circuitry, which could interfere with the readings.

author: bdunham7
author_rank: Super Contributor
timestamp: December 22, 2021, 11:53:01 pm
content: Quote from: Fungus on December 22, 2021, 11:27:03 pmDoes it not display ACV and Hz at the same time?

author: Fungus
author_rank: Super Contributor
timestamp: December 23, 2021, 08:19:58 am
content: Quote from: bdunham7 on December 22, 2021, 11:53:01 pmYes, but the Hz on AC volts range is different from the 5V, Hz/duty-cycle range.The OP mentioned duty cycle measurement and the 5V range, so...

author: bdunham7
author_rank: Super Contributor
timestamp: December 23, 2021, 05:21:11 pm
content: Quote from: Fungus on December 23, 2021, 08:19:58 amI had to look at a picture of the front of an 869S to figure out what you are referring to. So the Hz/%/ms (does it have pulsewidth?) function set is only available on the mVAC range, the other AC ranges only have Hz. That seems....odd. Or at least not what I'm used to and I'm not sure why it would be that way. And of course you're right, you can't go slamming 208VAC into the mVAC range and expect good things.

author: Fungus
author_rank: Super Contributor
timestamp: December 23, 2021, 06:57:53 pm
content: Quote from: bdunham7 on December 23, 2021, 05:21:11 pmThe mV range has higher bandwidth (Hz up to 1MHz), it's probably needed for the pulse width measurement.
8562A SA Display issue - Page 1
Forum section: electronics / testgear

author: SoundTech-LG
author_rank: Frequent Contributor
timestamp: December 23, 2021, 04:11:44 pm
content: Made a lowball offer on this SA because seller says it's an "adjustment" issue, to me though, it looks like a repair job.Was pretty sure I would get a counter-offer, but lo and behold seller did not counter offer, so appears I am the proud new owner.Anyone seen this before? It almost appears as some kind of retrace, but unsure.I guess once I get it it, I will know more how it behaves with any intensity level.Thanks in advance for your thoughtful insights.(I had 8562E in topic, but it is 8562A)
Minimun Pulse Width Measurement with a DMM? - Page 1
Forum section: electronics / testgear

author: DonpK
author_rank: Newbie
timestamp: December 22, 2021, 11:17:44 pm
content: I'm using a Siglent DMM3055 to measure current drawn by a microcontroller. The controller is put in a low-power mode using a watch-dog timer library. The controller "sleeps" for 60 seconds then wakes up and runs a few lines of code, then goes back into the low-power mode.The current measurement seems accurate - 25mA when awake and running the code and ca. 15µS when in the low-power mode. I am using the Trend Chart function on the DMM to track the current measurements. The measurements look okay - the current jumps to 25mA when the code is running, than back to 15µS. What doesn't look right is the length of time the current reading stays at 25mA. The current reading remains at 25mA for about a second even though the time it takes to run the code has to be only a few milliseconds.My question is what is the minimum current pulse length the DMM can measure? There could be a problem with my code, of course, but I want to make sure I'm using the DMM appropriately.

author: bob91343
author_rank: Super Contributor
timestamp: December 22, 2021, 11:58:51 pm
content: The meter doesn't care what the waveform is. It just reads the average. Of course, speed matters, so if the signal is very slow it will read first one value and then the other. The faster the jump between readings, the less time the meter has to go to the right value so it tends to read average.However, the devil is in the details. If the meter samples the input, it can get confused if the input changes while it's generatiing a display. Thus you will get nonesense and the way out of it would be to add a filter.

author: SL4P
author_rank: Super Contributor
timestamp: December 23, 2021, 12:38:47 am
content: You could get lucky with the frequency counter function if your meter has it.A little bit of maths

author: Caliaxy
author_rank: Frequent Contributor
timestamp: December 23, 2021, 03:40:25 am
content: Sounds like a great time to use an oscilloscope to check the pulse duration.SDM3055 is advertised as “up to 150 readings/sec”, which means a measurement every 6.7ms or longer. Maybe it’s even slower in trend mode? Are you using it in triggered mode? Have you tried lowering the precision (e.g. to 3 1/2 digits), to get more readings/s?Edit: Just checked the manual and learned that at 5 1/2 digit precision you can only get 5 readings/s in DCI, i.e. 200ms between readings, at best…

author: Picuino
author_rank: Super Contributor
timestamp: December 23, 2021, 10:32:17 am
content: You can power the circuit with a capacitor and measure the voltage drop of the capacitor when the circuit works. So you can easily measure the electrical charge consumed.

author: DonpK
author_rank: Newbie
timestamp: December 23, 2021, 12:47:52 pm
content: Thanks for the several good suggestions. I'll follow them up.
Can the old probe P6245 modify to fit new MDO3x? - Page 1
Forum section: electronics / testgear

author: zxq6
author_rank: Newbie
timestamp: December 23, 2021, 05:52:33 am
content: I have 4 old probe P6245, but the new MDO34 is not support the interface.If I can DIY to fit the new MDO 34?the TAP1500 is too expensive，and the interface transporter (TPA-BNC) is expensive too.Thanks!
BM235 reading speed - Page 1
Forum section: electronics / testgear

author: jdev99
author_rank: Regular Contributor
timestamp: December 27, 2021, 09:41:53 pm
content: I recently received a Megger AVO830 as a gift from my boss, have very nice features for electricians, but 1 very disappointing feature also. It is "very" slow to give a reading when measuring AC on autorange.1 feature I often use is the Loz function, but get very frustrated with the slow reading.So, the BM235 also do Loz, but how fast is it doing AC on autorange?I am considering getting one, if it is faster then the Megger.Related to this previous question:https://www.eevblog.com/forum/testgear/megger-avo830-info/msg3872840/#msg3872840

author: jdev99
author_rank: Regular Contributor
timestamp: December 28, 2021, 08:12:00 pm
content: Are there anybody that can take their BM235 and measure some 110/230V AC on autorange to see how long it takes to give a "valid" reading?And compare it to how long it takes if you use manual range selection.On my BM857, APPA 105R, UNI-T139E and my friend's Fluke 117, it takes less then 2 seconds in both cases.

author: Caliaxy
author_rank: Frequent Contributor
timestamp: December 28, 2021, 09:59:02 pm
content: It’s actually impressively fast. It reaches a stable reading in slightly more than a second (one Mississippi) in auto range and slightly less than a second in manual range. That’s almost twice as fast as its’ bigger brother BM789 (one Mississippi, two Mississippi) and also faster than my Fluke 87v in auto range.As requested, I only tried 120V AC. Let me know if you want me to count on more ranges

author: jdev99
author_rank: Regular Contributor
timestamp: December 29, 2021, 09:47:45 am
content: Thank you very much for the test. I thought it would be good, just had to confirm. This 1 test is all I wanted, thanx again.👍
does anyone have the keithley 1972/3 manual WITH schematic? - Page 1
Forum section: electronics / testgear

author: cnt
author_rank: Contributor
timestamp: December 23, 2021, 12:16:15 am
content: does anyone have the keithley 1972/3 manual WITH schematic?It would help my troubleshooting. the scans online don't seem to include the schematic. I guess they're provided by tek and they decided not to include schematics retroactively.

author: cnt
author_rank: Contributor
timestamp: December 23, 2021, 12:23:39 am
content: IDK why this ALWAYS happens but as soon as I ask for help I find what I need. Uploading it here for posterity. it says its the 5802 interface but it looks too close to my 1972 to be a coincidence.
Amp Clamp Overload - Is it Possible? - Page 1
Forum section: electronics / testgear

author: Shredhead
author_rank: Regular Contributor
timestamp: December 22, 2021, 08:13:06 pm
content: Got thishttps://www.kleintools.com/catalog/clamp-meters/acdc-digital-clamp-meter-auto-ranging-400-ampmeter to measure DC current on automobile as it's a pain to worry about the fuse popping on a regular multimeter inline.Is it possible to damage/destroy an amp clamp meter by measuring too high of a current in a setting? I'm not quite sure how Hall effect sensors are designed.I'm going to do a 10 turn wrap cord around the clamp to increase it's accuracy in it's lower ranges to measure parasitic drain but don't want to run into any problems as I plug fuses back in because the current can spike.

author: Fungus
author_rank: Super Contributor
timestamp: December 22, 2021, 09:09:40 pm
content: I don't think you can damage the sensor with a magnetic field but you can certainly magnetize the clamp and it will need degaussing afterwards.

author: GerryR
author_rank: Frequent Contributor
timestamp: December 22, 2021, 11:07:43 pm
content: With most of the clamp-meters I have used, when measuring DC current you have to zero the meter because of residual magnetism in the clamp after a reading. The zero function is part of the meter.
Determine the MultiMeter best to measure current, - Page 1
Forum section: electronics / testgear

author: abdulbadii
author_rank: Frequent Contributor
timestamp: December 21, 2021, 02:02:34 pm
content: Which MultiMeter best to measure current, analog or digital ?what technical method is it?

author: BeBuLamar
author_rank: Super Contributor
timestamp: December 21, 2021, 02:13:27 pm
content: What kind of current? AC or DC? How much current? mA ranges or hundred of Amperes?

author: abdulbadii
author_rank: Frequent Contributor
timestamp: December 21, 2021, 02:17:30 pm
content: Quote from: BeBuLamar on December 21, 2021, 02:13:27 pmcurrent just current, AC, DC, or etc rate just rate 0.0000001 A or 999 A or etc.

author: BeBuLamar
author_rank: Super Contributor
timestamp: December 21, 2021, 02:24:08 pm
content: If you only asked analog or digital then I must say digital. Now if you measure very low current a multimeter would be better than the clamp meter. If you measure 999A then a clamp meter is better. So there is no best for all current measurement.

author: alm
author_rank: Super Contributor
timestamp: December 21, 2021, 11:37:48 pm
content: What's best? Highest accuracy? Lowest burden voltage? Fastest measurement speed? Most convenient? Any constraints?Highest accuracy for DC pA? Probably a Keithley or Keysight electrometer. DC mA? Probably Fluke 8588A. Tens or hundreds of A DC? Maybe a LEM DCCT?Lowest burden voltage? For mA and lower ranges, a feedback ammeter. For higher ranges either a very low value shunt (like uCurrent), a DCCT or a Hall effect sensor.

author: RolandK
author_rank: Regular Contributor
timestamp: December 22, 2021, 03:52:33 pm
content: The thinking of "there ist one best for all" ist very wide spread in all fields, but only shows that someone has no clue what he or she wants to use it for.There are allways conditions, which should be met, not only technical like resolution, range, error, speed, interfaces,but also non-technical like size, user-friendliness, envionment-proof, development- or production-cost, size of market, regulatory settings, colour or design.Therefore to get some hint, you should know what you want to use your instrument for in which environment. E.G.- Repair of motors on a vessel- playing with radio-ciruits at home- high-voltage installations outdoors- controlling the charge current of li-ions of your tesla car.- meassuring discharge currents of lightningsSo first tell us what you think is "clear" for everybody and not such bla bla as from 0.0000000000000000000001 to 9999999999999999 A or you get only bla bla answers like this one.

author: Gyro
author_rank: Super Contributor
timestamp: December 22, 2021, 07:52:27 pm
content: The OP almost never comes back to reply or clarify his requests.

author: BeBuLamar
author_rank: Super Contributor
timestamp: December 22, 2021, 10:27:28 pm
content: Quote from: Gyro on December 22, 2021, 07:52:27 pmHe did after my response to him asking what kind of current he wanted to measure. He came back and said current period. He wanted the best meter to measure current AC and DC, very low to very high. So he wanted a do it all current meter.
TEK 2465B NVRAM selection?  - Page 1
Forum section: electronics / testgear

author: jonpaul
author_rank: Super Contributor
timestamp: December 22, 2021, 04:33:12 pm
content: Bonjour, still working on 2465B with many defects, and all options. CTT, GPIB, WR.A5 has had SMD lytics replaced, no corrosion damages, socketed the NVRAM.Looking on the distr, the original DC1225Y-200 is replaced by several other versions, by Maxim, suffix AD, AB and various speeds.Speeds are not important but what's différence original Y and AB and AD suffix?Many thanksJon

author: David Hess
author_rank: Super Contributor
timestamp: December 22, 2021, 07:55:48 pm
content: The suffix defines the supply voltage where the battery backed up SRAM disables external operations. It is specified in the datasheet.
Are all cheap DMM temp probes the same? - Page 1
Forum section: electronics / testgear

author: eti
author_rank: Super Contributor
timestamp: December 22, 2021, 10:00:11 pm
content: HelloAre all cheap DMM temp probes the same? I had to dispose of one, and I have a couple of other spares from cheap DMMs - the spare I have to hand is "TP Series".Thank you and Happy Christmas.

author: BeBuLamar
author_rank: Super Contributor
timestamp: December 22, 2021, 10:28:31 pm
content: All DMM I know use type K thermocouple so you can use any type K thermocouple and it would be fine.

author: eti
author_rank: Super Contributor
timestamp: December 22, 2021, 11:14:46 pm
content: Quote from: BeBuLamar on December 22, 2021, 10:28:31 pmMuch appreciated, thank you and Happy Christmas!

author: Cerebus
author_rank: Super Contributor
timestamp: December 22, 2021, 11:33:11 pm
content: Quote from: BeBuLamar on December 22, 2021, 10:28:31 pmI'd say that in my experience most use either NTC thermistors or PT100 platinum resistance sensors. I'd say that on balance more 'cheap' multimeters use 10k or 100k NTC thermistors than thermocouples. The electronics for measuring resistance are already there, whereas thermocouples require additional electronics capable of amplifying the typical 1mV at room temperature of a type K thermocoupleandcold junction compensation. PT100 sensors are more likely on decent bench DMMs, possibly as an additional alternative to NTCs.

author: eti
author_rank: Super Contributor
timestamp: December 22, 2021, 11:48:34 pm
content: Quote from: Cerebus on December 22, 2021, 11:33:11 pmEvery DMM I've ever owned has been a thermocouple, and these definitely are those - a welded fused bead, and the leads are sheathed in woven fibreglass.

author: Cerebus
author_rank: Super Contributor
timestamp: December 23, 2021, 02:09:57 am
content: Quote from: eti on December 22, 2021, 11:48:34 pmNo doubt that's a thermocouple but I'd still contend that's unusual on cheap multimeters in my experience. Itisbound to be type K, I've never seen anything other than type K on cheaper instruments.
UT139C missing battery cover screw insert? - Page 1
Forum section: electronics / testgear

author: jrmymllr
author_rank: Regular Contributor
timestamp: December 17, 2021, 07:33:52 pm
content: I ordered a UT139C off eBay and direct shipped from China. It arrived in an outer box covered in Uni-Trend tape and the actual box inside looks normal with a cal cert and manual (in Chinese, oh well).As I was loosening the battery cover screw, it made a crack noise, like plastic giving way. Slightly concerning, but I got the screw out. When I put the battery cover back on and attempted to tighten the screw, it kept turning, turning, turning, never tightening. I found that the only way to get the screw back out was to lightly pull on the battery cover as I loosened the screw.There appears to be no metal insert in the battery cover screw post. Teardowns like this one (https://lygte-info.dk/pic/UNI-T/UT139C/DSC_2721a.jpg) and others online clearly show a brass insert.I messaged the seller. I don't know if they did some cost cutting or what, but the battery cover screw is still a fine thread type not appropriate for direct into plastic. I believe the "crack" I heard was some of the plastic threads breaking off because I took the rear cover off and everything looks good, except for no brass insert.Anyone have a recent UN139C with or without an insert?

author: jrmymllr
author_rank: Regular Contributor
timestamp: December 21, 2021, 04:50:48 pm
content: Alright well I'm planning to send this back regardless. I could install an insert, but the seller is willing to only refund me a few dollars which won't cover the trouble of determining the size/type and the cost of obtaining one.Hope the replacement isn't missing this.
How to improve the diode gear of the FLUKE-27/FM multimeter to increase the meas - Page 1
Forum section: electronics / testgear

author: daisizhou
author_rank: Super Contributor
timestamp: December 20, 2021, 03:10:20 am
content: I have a fluke 27/fm multimeter.Its diode file output voltage is around 2.60V.Under normal circumstances, when measuring the NMOS tube, the MOS tube cannot be driven to turn on, so it is impossible to quickly determine whether it is damaged.Can the output voltage be adjusted to 5.1V to be the same as the FLUKE 187 diode voltage?

author: Shock
author_rank: Super Contributor
timestamp: December 20, 2021, 04:47:01 am
content: Tested my Fluke 189 and got about 5.1 open circuit as well. My mistake I think I misread the range as the open circuit value in the manual. It's mentioned in several places.

author: daisizhou
author_rank: Super Contributor
timestamp: December 20, 2021, 05:45:37 am
content: Please take a closer look at the photos I took above.The picture is my measured voltage 187

author: daisizhou
author_rank: Super Contributor
timestamp: December 21, 2021, 06:13:58 am
content: Does anyone have a way to successfully adjust?help
Keithley 2440 Sourcemeter voltage read back fluctuation  - Page 1
Forum section: electronics / testgear

author: analogRF
author_rank: Super Contributor
timestamp: December 22, 2021, 02:32:17 am
content: Finally I got my first Keithley sourcemeter (already had a bulky and long Advantest R6243). It is a 2440 5A version which was booting fine without any errors but there was nothing in the output.So it turns out the +/-15VF rails were dead which was easily fixed and the unit works fine now albeit a bit out of spec in lower ranges but spot on in higher ranges.But there is one problem that I cannot figure where and how to troubleshoot. Although the I/V source is rock solid but the readback specially in voltage has this weird fluctuations on the last few digits when in low ranges which gradually disappears as i move to higher ranges with less decimal digits. For example if I am measuring 1.000000 the last 4 digits fluctuate in what I believe is some kind of pattern. It appears they increase over several triggers and then suddenly drop to almost zero and this pattern repeats. At least that's how it feels. In higher ranges with less decimal digits the fluctuation is less and finally disappears for example when I measure 40.000 VCurrent measurement seems much better although again the last 2-3 digits seem too unstable for me.Any idea where and what I should be looking at?Supply voltages have no noise or spike. What are the components involved with the A/D?Manual says U610 Gate array controls the ADC but for the life of me I cannot see U610 anywhere. I see U600 - U609 and then U650....attached is a picture of the analog boardEDIT: is there any schematics from Keithley multimeters that can help troubleshooting the "multimeter" function of this sourcemeter?

author: analogRF
author_rank: Super Contributor
timestamp: December 22, 2021, 12:03:18 pm
content: it appears there is an error in the manual and U610 is in fact U609 (Altera FPGA) on the board. That is the only gate array I can see.there are also some stuff that are wrong on the PCB silk screen such as +/-85V and +/-42V which are in fact is +/-58V and +/-23V, respectively.But still the question remains which components make up the multi-slope ADC? Does anybody know? Is it similar to some Keithley DMMs with available schematics perhaps?

author: julian1
author_rank: Frequent Contributor
timestamp: December 23, 2021, 12:11:22 am
content: The altera max and circuitry underneath it (I think a hct175 flip/flop, and sd5400 fet switch and comparator) is the adc. It has to send the serialized counts back through the optocouplers on the rhs of the board. So perhaps it is worthwhile to inspect the soldering joints/supplies around the cpld/optocouplers. Although if the error is range dependent that seems a bit odd.How did you fix the +-15V supplies? With so many rails voltages being wrong, maybe that's a better place to look. I *think* that +24V is the main high current supply, from which everything else gets derived. It comes from the bottom board, but there should be a test point on the top board somewhere.
HP6140A - digital current source - searching for complete manual - Page 1
Forum section: electronics / testgear

author: Calvin
author_rank: Regular Contributor
timestamp: December 19, 2021, 04:24:34 pm
content: Hi,I´m searching for a complete service manual of the HP6140A digital current source.The downloadable file on the keysight website isn´t complete.Schematics etc for a couple of boards are missing, such as the A/D converter board etc.Does anyone happen to have a complete manual or a scan of it?regardsCalvin

author: GerryR
author_rank: Frequent Contributor
timestamp: December 20, 2021, 08:45:16 pm
content: The one I downloaded from Keysight appears to have all the schematics. The d/a converter board is on schematic sheet 1. I would attach but it is 5.75 Mb, so too big to attach. Check the size of your download and if different, PM me your email if you want me to send the file to you.

author: Calvin
author_rank: Regular Contributor
timestamp: December 21, 2021, 05:57:05 am
content: Hi,ahh, I see. They put several schematics into a single big schematic and mixed block schematics and detailed schematics into one.Unfortunately the scan quality is poor and a lot of symbols and texts are almost unreadable.It´d great if anyone could provide for higher quality scans of Figures 7-2 (sheet 1-5).Thank you so muchCalvin
What could be a similar model to Agilent E3644 ?  - Page 1
Forum section: electronics / testgear

author: electronic_guy
author_rank: Regular Contributor
timestamp: December 20, 2021, 04:50:18 pm
content: Similar power supply model

author: tggzzz
author_rank: Super Contributor
timestamp: December 20, 2021, 04:55:36 pm
content: Look at the fleabay "sold" items to find the prices paid. Note that it won't show the "offer accepted" price.

author: gamalot
author_rank: Super Contributor
timestamp: December 20, 2021, 05:45:59 pm
content: Is there something wrong with this forum?

author: dorkshoei
author_rank: Frequent Contributor
timestamp: December 20, 2021, 05:48:23 pm
content: Quote from: gamalot on December 20, 2021, 05:45:59 pmThe OP edited the first post at 5.41. I suspect they changed the title of the thread. You can do that but the replies that existed before the edit still keep the title of the original thread. Replies after the edit get the new title.Now why the OP did this, changing the title to something totally different, is a good question.

author: tggzzz
author_rank: Super Contributor
timestamp: December 20, 2021, 07:56:20 pm
content: Quote from: dorkshoei on December 20, 2021, 05:48:23 pmUnless there is agoodanswer, then given the OP's moniker my response will be PLONK

author: Cerebus
author_rank: Super Contributor
timestamp: December 20, 2021, 08:00:47 pm
content: Quote from: tggzzz on December 20, 2021, 07:56:20 pmPresumably indicating the acronym that used to feature in British Policemen's notes?
Tektronix 2710 Options - Page 1
Forum section: electronics / testgear

author: KCT_99
author_rank: Regular Contributor
timestamp: December 18, 2021, 04:48:45 am
content: I recently got a Tektronix 2710 in nearly mint condition but it does not have an option sticker on it.When I navigate to the installed options screen it says300Hz Filter 300kHz FilterPhase Lock CentronixNVM12.88I am not sure exactly what options these are. Can someone enlighten me on this ?

author: ToThePub
author_rank: Contributor
timestamp: December 18, 2021, 05:17:16 am
content: https://w140.com/tekwiki/wiki/2710Has all the info you need including the manual which talks about the options.

author: David Hess
author_rank: Super Contributor
timestamp: December 18, 2021, 05:27:53 am
content: The page here describes the options better than my 1991 Tektronix catalog:https://w140.com/tekwiki/wiki/2710It looks like you have options 01, 09, and 11. The manual available on that page may tell more.

author: KCT_99
author_rank: Regular Contributor
timestamp: December 20, 2021, 01:49:10 pm
content: I do have the manual, but it is not clear to me what options I have installed.Thanks David for translating this for me.
Strange signal at 25Mhz in ROHDE&SCHWARZ FPC1500 - Page 1
Forum section: electronics / testgear

author: Antonino
author_rank: Newbie
timestamp: March 17, 2021, 05:51:25 pm
content: Rf Input 50 Ohm terminated.I can see this.All are working ok?

author: marku5
author_rank: Newbie
timestamp: December 19, 2021, 10:36:40 am
content: same on my device, and another phantom signal at 800MHz.

author: Qw3rtzuiop
author_rank: Frequent Contributor
timestamp: December 19, 2021, 10:49:18 am
content: Seems to be within specs.
Datron Wavetek 4920M, 4920 docs and 4922 docs - Page 1
Forum section: electronics / testgear

author: volvo_nut_v70
author_rank: Regular Contributor
timestamp: December 19, 2021, 04:29:48 am
content: I have received the ECOs for the 4920M, the schematics for the 4920 that differ from the 4920M, 4920 ECOs, 4920 training guide and the 4922 Op manual, 4922 schematics and 4922 ECO.I have combined the 4920 files into a "super" 4920/4920M/4950 Vol 2 manual and a separate 4922 op/svc manual with the Op, schematics and ECO.I've gone that route since one of the docs is a compatibility note on boards between the 4920/4920M/4950. I have attached it here.I've uploaded the docs to BAMA, Ko44b, XDEVFor instant gratification:https://doc.xdevs.com/docs/Wavetek/4920/Datron_Wavetek_4920_4920M_4950_Service_Manual_Vol-2.pdfhttps://doc.xdevs.com/docs/Wavetek/4922/Datron_Wavetek_4922_um_sm.pdf

author: TheSteve
author_rank: Unknown
timestamp: December 19, 2021, 04:51:56 am
content: Thanks Ken,I believe the proper TiN approved URL's would be:https://xdevs.com/doc/Wavetek/4920/Datron_Wavetek_4920_4920M_4950_Service_Manual_Vol-2.pdfhttps://xdevs.com/doc/Wavetek/4922/Datron_Wavetek_4922_um_sm.pdf

author: perdrix
author_rank: Frequent Contributor
timestamp: December 19, 2021, 04:41:27 pm
content: Please could you also upload to the files section of the Datron-Wavetek group at groups.ioThanksDavid
HP 8114A - Page 1
Forum section: electronics / testgear

author: ttbelectronics
author_rank: Contributor
timestamp: September 22, 2020, 10:22:17 pm
content: I have a Power Supply used on HP 8114A Pulse Generator and someone took man parts out, I got the unit running but still some voltages only half the value.I believe 2 Zener Diodes are wrong part numbers.Can someone have in hands the part number for VR501 and VR509?Thank you.

author: 0culus
author_rank: Super Contributor
timestamp: September 22, 2020, 10:26:14 pm
content: I'm sure the manual for this is available scanned online. Have you checked Keysight or BAMA (boat anchor manual archive)?

author: ttbelectronics
author_rank: Contributor
timestamp: September 22, 2020, 10:34:51 pm
content: Yes I have the Manual but not part list.Will need actually someone look the Power Supply and get the number direct from the part.

author: 0culus
author_rank: Super Contributor
timestamp: September 23, 2020, 01:59:29 am
content: I see now...this is one of the newer boxes from the 1990s when service manuals started to not be released. Good luck, hopefully someone has one they can look inside for you.

author: ttbelectronics
author_rank: Contributor
timestamp: September 23, 2020, 02:03:43 am
content: Thank you.

author: CodingMarco
author_rank: Contributor
timestamp: December 19, 2021, 01:39:30 am
content: Hi,The following part numbers are from the 8114A CLIP:VR501 is part number 1902-0955 (Zener Diode 7.5V, 5%, MPN: Microsemi 1N958B-1E3/TR). It was/is available from several manufacturers, see the attached image.VR509 is part number 1902-0954 (Zener Diode 15V, 5%, MPN: Microsemi 1N957B-1E3/TR).I have also uploaded a scan of the full CLIP to KO4BB, it's only waiting for approval.: It's here:http://www.ko4bb.com/getsimple/index.php?id=download&file=HP_Agilent/HP_8114A_Pulse_Generator/HP_8114A_High_Power_Pulse_Generator_CLIP_08114-91031.pdf
AC RMS Current Measurement Using the Siglent SDS2000X Plus Oscilloscope - Page 1
Forum section: electronics / testgear

author: 2N3055
author_rank: Super Contributor
timestamp: December 17, 2021, 10:34:55 am
content: Just a few notes.First, you can keep multimeter in the loop and use current transformer at the same time. That will allow you to compare current in real time. Also you can enable statistics on multimeter and use mean value. That would allow for better accuracy.On the scope, there is no need for math channel for this. You should enter input channel settings. First, set channel to current (A) not voltage (V). That will make scope show proper physical units (A). And then enter probe submenu and there you can enter decimal probe factor. Enter your conversion factor here.Now you will have a channel that show proper value (scaled for probe factor), proper physical unit (A) and all that without using math channel.And if you connect, for instance, a (differential !) voltage probe of voltage across that lamp, you can use math channel to multiply current and voltage channel and get real-time power curve. Or do all kinds of other analysis..

author: hesam.moshiri
author_rank: Regular Contributor
timestamp: December 18, 2021, 09:09:21 am
content: Quote from: 2N3055 on December 17, 2021, 10:34:55 amThat's right, the intention was to demonstrate the formula editor feature by a practical example.
New Aneng manual range meter SZ08 ! - Page 1
Forum section: electronics / testgear

author: Fungus
author_rank: Super Contributor
timestamp: December 20, 2021, 11:21:43 am
content: https://www.aliexpress.com/item/1005003536067154.htmlIt has clip-on cover to hold the leads and protect the screen when in storage.Powered by 2 * 1.5V AAA batteries.Wonder what the diode test voltage is? Why do they never tell us that?

author: Fungus
author_rank: Super Contributor
timestamp: December 20, 2021, 11:33:10 am
content: I just noticed it doesn't have any fake CAT rating on the front.(It also doesn't claim to be "anti burn" on the Aliexpress page.)

author: Gyro
author_rank: Super Contributor
timestamp: December 20, 2021, 12:32:45 pm
content: Yes, at least that's honest. I'm pretty sure you can't have a sensible Cat rating on anything with a relatively exposed transistor test socket.

author: Fungus
author_rank: Super Contributor
timestamp: December 20, 2021, 01:56:29 pm
content: I wonder who makes it? It's not on the Zotek web site.

author: joeqsmith
author_rank: Super Contributor
timestamp: December 20, 2021, 02:05:09 pm
content: Quote from: Fungus on December 20, 2021, 11:33:10 amThat's alright. It maintains the CE mark.

author: rsjsouza
author_rank: Super Contributor
timestamp: December 20, 2021, 03:30:00 pm
content: Quote from: Fungus on December 20, 2021, 11:21:43 amThe Aneng M118A has all the specs in the frontQuote from: joeqsmith on December 20, 2021, 02:05:09 pmCE = China Export.
Rigol RSA3000/5000 spectrum analyzers: question for owners or operators - Page 1
Forum section: electronics / testgear

author: VK6HP
author_rank: Newbie
timestamp: December 26, 2021, 09:39:04 am
content: Hello everyone,I have a Rigol RSA3015E-TG analyzer and have been largely satisfied with it in the 15 months or so I've owned it. A couple of months ago I noticed an anomaly with the noise floor and calibration in the wideband real-time (RSA) mode, whereby the noise floor of the instrument jumps many tens of dB once spans (FFT total bandwidth) exceed exactly 3 MHz, sensitivity is much reduced, calibration of levels is wildly inaccurate and large baseline curvature is evident over e.g. 5 or 10 MHz spans (spectra unable to be aligned or flattened). RSA behaviour below 3 MHz is pretty much normal, as is GPSA (sweeping analyzer) operation.The analyzer is still under warranty and I just received it back from Rigol after the Australian distributor arranged for it to be sent back to China for repair. Unhappily, the bad behaviour persists. With the holiday season now upon us, nothing much further can happen until early January. In the meantime, I'd be interested to hear from any other owners who might be able to report their RSA noise floors at (say) 100 MHz, with spans of 100 kHz, 1 MHz, 5 MHz and 10 MHz. (If you have a fancier analyzer version with more bandwidth, feel free to go further). No need for much accuracy: the effect I see is a huge one.Most likely this RSA issue is simply a fault in my instrument but I've been surprised at what's gone unnoticed (or unadvised) in the past - for example, my report of a ~12 MHz noise floor step seemingly triggered a Rigol web FAQ to re-assure RSA3000/5000 owners that calibration is not affected. A quick look at the just-returned analyzer leads me to think that Rigol have now upgraded the firmware/hardware to mitigate this previously-noted effect.Thanks, and regards,Peter.
R&S Polyscope II for free - Page 1
Forum section: electronics / testgear

author: techneut
author_rank: Regular Contributor
timestamp: December 17, 2021, 05:38:19 pm
content: I have a Polyscope II that was in working condition 25 years ago. It hasn't been powered on sinds. So it will need a lot of TLC to be operational again. I have the manuals and also some probes. For someone with a lot of time and care for old equipment in the Netherlands because shipment is out of the question due to weight.I posted this also in groups-io R&S
465M parts give away - Page 1
Forum section: electronics / testgear

author: andy3055
author_rank: Super Contributor
timestamp: October 16, 2021, 11:05:48 pm
content: After repairing my old 465M, I got a bunch of spares that I can give away. Conditions are unknown for the most part unless noticed otherwise. If you are in the bay area, I can arrange for you to pick up from my home. If shipping is involved, I will use FedEx or USPS with tracking and charge actual costs.1. Main board with Power supply complete. Has a good HV transformer but U 550 block is defective.2. Main board minus U 550 block and HV transformer.3. Vertical module-CH 1, knob missing and outer pot shaft broken.4. Time base-known to be faulty.5. Case with handle and inside shield complete.If interested, please PM for info. I will be away from 22nd Oct. to the 6th Nov.Vertical Module is taken.I also have 2 CRTs for this same scope.Thanks.

author: andy3055
author_rank: Super Contributor
timestamp: November 07, 2021, 04:24:15 am
content: Vertical Module has been taken. Other parts are still available.

author: james_s
author_rank: Super Contributor
timestamp: November 07, 2021, 06:35:21 am
content: IIRC the CRT will work in a 465B too, I think it's what the tube in mine came from. The CRTs are probably the most useful parts.

author: andy3055
author_rank: Super Contributor
timestamp: November 07, 2021, 03:19:02 pm
content: Thanks, James. There are also rare components in the timebase modules. I have no way of checking them. Also, I do not want to keep these if it can be used by someone else.

author: andy3055
author_rank: Super Contributor
timestamp: December 17, 2021, 02:57:47 pm
content: All parts are gone to a good home.
Rigol DL3021 / DL3021A Electronic Load - How to reset System Boot Times? - Page 1
Forum section: electronics / testgear

author: KlausF
author_rank: Contributor
timestamp: December 16, 2021, 04:50:52 pm
content: Hi guys!Any idea how to disable or reset the "System boot times" counter (Utility menu -> System Information) of Rigol DL3021(A) ?

author: tokojelek
author_rank: Newbie
timestamp: December 17, 2021, 02:29:54 pm
content: I think this feature is not available yet by use of SCPI, not see it in the RIGOL - Programming Guide of DL3000Mine is also broken, after testing battery for about 2-3 days without turn of in room temperature. some component got burned.Be ware of powered this RIGOL DL3000 device in long time measurement, it's not reliable and durable ...
Boonton 8220 FM Deviation Meter? - Page 1
Forum section: electronics / testgear

author: wa2pux
author_rank: Contributor
timestamp: December 16, 2021, 09:20:11 pm
content: Does anyone have schematics, service manual and the like on this Boonton FM deviation meter.This one is only semi-functional and I'd like to get it fully functional.Without information, there is no hope.
Uni T UPO 2104CS Osciloscope Software - Page 1
Forum section: electronics / testgear

author: martinignaciosf
author_rank: Newbie
timestamp: December 15, 2021, 08:02:41 pm
content: Hello Forum, I recently got a Uni T osciloscope but I can't find the software to connect it to the pc or the new firmware versions, they aren't listed anymore on their website and trying with the wayback machine just ends up in a missing google drive link, by any chance any of you would have an alternate link?

author: KlausF
author_rank: Contributor
timestamp: December 16, 2021, 05:05:55 pm
content: Maybe some distributors still have Firmware on their sites.Just like that, but I guess it is Software not Firmware in this case.https://www.reichelt.de/en/en/digital-speicher-oszilloskop-70-mhz-4-kanaele-ultra-phosphor-upo-2074cs-p239599.html?PROVID=2788&gclid=EAIaIQobChMItqiYyebo9AIVB41oCR31JgIbEAQYASABEgKeevD_BwE&&r=1