hybridfree/eevblog-posts huggingface dataset:
Fluke 233 - No more dead battery hack - Page 1
Forum section: electronics / testgear

author: stempile
author_rank: Contributor
timestamp: October 08, 2013, 04:19:52 am
content: My first and only Fluke meter so far is the 233 - Remote Display True RMS. It has all the functions I would need and the radio linked head is pretty interesting. Problem was that the unit has a heart beat between the body and the head, even when "off". Research indicated this is because the meter can be turned on remotely. When the head is installed on the body it uses IR rather than RF to save the AA batteries (2 in the head and 3 in the body).Because I use the meter on the bench for hobby work and not in the field, it didn't get use a lot and should last for months with intermittent use. I was finding it dead within 2 months. Research uncovered the heart beat feature as the reason. For my purposes, I didn't purchase the best option - oppps. No chance in selling it, lots of eBay entries already.I set out to hack in a toggle switch on both the head and body between the battery terminals. This would give a HARD off rather than the soft off while running heart beat.First goal was to hack it with significant modification. This worked for about a year and proved the concept.For the long term hack, I opened up the meter and installed micro toggles inside and sealed up to maintain the ruggedness of the unit. So far it has been solid provided I don't forget to turn off the toggle switches.The setup has both switches in line so one swipe gets them both. This was a significant improvement over the first attempt.

author: retiredcaps
author_rank: Super Contributor
timestamp: October 08, 2013, 06:18:04 am
content: Fluke released a new firmware for the 233 (2.0, I think) that helps prolong the battery life.

author: stempile
author_rank: Contributor
timestamp: October 08, 2013, 03:32:43 pm
content: Firmware update on a non-field programmable meter wasn't the first thing I would think of. I checked out the Fluke site, no specific mention of this on the support page.Google searched and found a recent conversation on the element14 site. The process is calling Fluke, requesting the upgrade (plus calibration) and only paying for shipping both ways.I purchased the meter several years ago locally. I had just expected the performance as this is how it works and gave up seeking any resolution. It would seem enough people had complained about it in order to warrant the release of the firmware.Given that I have a solution, is it worth the hassle of shipping it off? Not sure yet. Also now that I have physically modified the device, will Fluke even touch it? I doubt it. I will likely call and find out either way, I am curious now.Thanks for the tip!!
TENMA - 72-10495 any info/reviews? - Page 1
Forum section: electronics / testgear

author: trevwhite
author_rank: Frequent Contributor
timestamp: October 08, 2013, 10:19:29 am
content: I am thinking about buying one of these power supplies.http://uk.farnell.com/tenma/72-10495/psu-bench-dual-5a-30v/dp/2251947I can't seem to find much information on them but the specification looks okay.CheersTrev

author: urbis
author_rank: Unknown
timestamp: October 08, 2013, 10:42:50 am
content: Looks like a rebadged KORAD KA3005D, which has been mentioned quite a lot on here.

author: trevwhite
author_rank: Frequent Contributor
timestamp: October 08, 2013, 01:18:31 pm
content: Thanks, that was really useful. Found everything I needed to.
Are there any sun $100 usd differential probe - Page 1
Forum section: electronics / testgear

author: bhilly82
author_rank: Contributor
timestamp: October 08, 2013, 10:28:52 am
content: I am looking at getting a differential probe. I am just hopping there is one out there i can pick up for under $100 usd. I just cant seem to find one for under $180.

author: BravoV
author_rank: Super Contributor
timestamp: October 08, 2013, 10:51:09 am
content: Sure, got mine in Aug from this deal ->http://www.ebay.com/itm/261264797650, created a discussion thread about it ->Here
Broken HP 8903E - all lit up, unresponsive - Page 1
Forum section: electronics / testgear

author: uoficowboy
author_rank: Regular Contributor
timestamp: June 13, 2013, 06:03:05 am
content: Hi - I have an HP 8903E for the next little while. It'd be nice to fix it. The device is dead - when turned on all LEDs light up ('8's on the 7 segment displays, all LEDs turn on except for the one on the button labeled "s". It does not react to any buttons being pressed.Anybody have any suggestions as to where to start with this beast?I measured the supply rails. 5V was dead on, 12V was at 10.8V, -15V and +15V both looked good.I didn't see schematics anywhere so I was not sure where to go next.Thanks!!

author: vk2hmc
author_rank: Contributor
timestamp: October 07, 2013, 08:59:20 pm
content: The 8903E is basically an 8903B minus the sweeper/generator part.I seem to remember that the 8903E measurement floor has better specification.However, the good news is the 8903B manual is used to troubleshoot your unit.The 8903B service manual is here:http://cp.literature.agilent.com/litweb/pdf/08903-90062.pdfLater revision here:http://cp.literature.agilent.com/litweb/pdf/08903-90062V2.pdf(! check serial number range for which manual to use)FWIW, The Cal Manual is here:http://cp.literature.agilent.com/litweb/pdf/08903-90053.pdf--marki

author: macboy
author_rank: Super Contributor
timestamp: October 07, 2013, 09:52:02 pm
content: Quote from: vk2hmc on October 07, 2013, 08:59:20 pmThat's volume 1 and 2, not version 1 and 2. You need both volumes for the complete manual.There are fairly detailed troubleshooting procedures in the manual. After you find what is dragging down the 12V supply, try them.

author: vk2hmc
author_rank: Contributor
timestamp: October 07, 2013, 10:11:12 pm
content: I stand corrected, the PDFS are volume one and two of the service manual.That will teach me to go from memorythanks,--marki

author: vk2hmc
author_rank: Contributor
timestamp: October 07, 2013, 10:11:58 pm
content: OP should check the serial is covered in the downloadable PDF's.The more recent instruments are not covered in these manuals.However there are addendum to bring them up to date.To reiterate, including Macman's suggestion, Download the service manuals.Run through the 12v PSU troubleshooting tree and if stuck, post back heregood luck,--marki
Agilent U1232A - Small offset on DC-voltage after measuring resistance. - Page 1
Forum section: electronics / testgear

author: Spike101
author_rank: Contributor
timestamp: September 07, 2013, 09:20:16 am
content: Hi,I got an Agilent U1232A DMM and i have the following problem with it:When I turn it directly to to DC-V range and short out the leads, i get 0.0mV as expected. However, if i first make some resistance measurement, then go back to the DC-V range and short out the leads, it reads -0.7mV to -1.0mV (lower resistance measurements seem to make the offset higher - i.e. when i short out the leads in resistance mode, the offset is higher. If i just let it sit in resistance mode for a few seconds without making any actual measurements it is lower).Turning the meter off and on again, immediately fixes the problem.Do you have any ideas what could be wrong? Or is this normal for this DMM?It is not really a big problem, because it is fixed by turning the DMM off and on again, but it's still a bit annoying..

author: Dave
author_rank: Super Contributor
timestamp: September 07, 2013, 03:58:11 pm
content: I just tested this and I can confirm that my U1232A does the same.I get -1.7mV when I set the meter to the lowest resistance range, keep the leads open, switch back to voltage and short out the leads.However, I don't get any offset if I keep the leads shorted the entire time.

author: Thompson
author_rank: Newbie
timestamp: September 10, 2013, 02:20:37 pm
content: I own a U1233A and it does exactly the same.

author: Spike101
author_rank: Contributor
timestamp: September 10, 2013, 04:50:20 pm
content: Thanks for the confirmation. I guess i have to live with it then..

author: shk1d29
author_rank: Contributor
timestamp: October 07, 2013, 08:54:19 pm
content: Have any of you guys tried to use the BT module for this DMM?There seems to be an inherent problem with it.
50USD osciloscope Iwatsu SS-5702 - Page 1
Forum section: electronics / testgear

author: locoo
author_rank: Contributor
timestamp: October 07, 2013, 09:49:45 am
content: Hello everybody , thanks to the eevblog the video i went to ebay and started to look for scopes and found this one and it was good.Manualhttp://www.ece.rice.edu/~jdw/data_sheets/ss5702.pdf
Fan noise of the BK Precision 9130 power supply - Page 1
Forum section: electronics / testgear

author: Ronald1962
author_rank: Contributor
timestamp: October 07, 2013, 05:23:41 pm
content: Hi guys,I got the BK Precision 9130 power supply (used) for 325,00 €.It works fine!Unfortunately this thing has very noisy fans running even if thereis nothing connected to it.I could not find a way to get rid of this. My other psu's only startup their fans when they "have to work heavily".Does anybody know if the 9130 is designed in this way?Maybe somthing is broken...Hope somebody can give any hints.Thanks a lot it advance.RegardsRonald
Input termination - what's the point? - Page 1
Forum section: electronics / testgear

author: microbug
author_rank: Frequent Contributor
timestamp: October 07, 2013, 03:27:37 pm
content: I recently bought an old 20MHz analogue scope and needed a cheap DDS or arbitrary wave gen, so I bought an AD9850 module from eBay. I noticed (through measuring) that it has a 1 megohm input impedance, but I frequently hear Dave talking about a 50 ohm terminator. Why is this needed? Do some function generators have a minimum load or is it something to do with current and noise etc. . Answers appreciated!

author: c4757p
author_rank: Super Contributor
timestamp: October 07, 2013, 03:37:21 pm
content: The inductance and capacitance of the coax cable that you connect to it cause the cable to have what is called a "characteristic impedance" - usually 50 ohms. This means that before the signal has time to get to the end of the cable and back (about 5 nanoseconds per meter), the cable looks like a 50 ohm load. After the signal reaches the end, that load changes from the characteristic impedance to whatever load is at the end of the cable. That impedance change will distort the signal and cause reflections. By matching the two impedances, you make sure that the overall impedance of the system never changes.This is generally only of concern when the signal frequency gets near the propagation delay. Of course, keep in mind that square waves have high frequency content well above their main frequency.

author: microbug
author_rank: Frequent Contributor
timestamp: October 07, 2013, 03:44:38 pm
content: Thanks!
Hioki 7005 DC Standard calibration - Page 1
Forum section: electronics / testgear

author: e61_phil
author_rank: Frequent Contributor
timestamp: September 26, 2013, 11:48:19 am
content: Hello,I've bought a Hioki 7005 DC Standard on ebay and it is a little bit out, so I would like to adjust it. I already asked Hioki (ASM GmbH in Germany) but they don't have any service documents for this old device.Has anyone here such documents? Or any tips for calibration?Thanks a lotPhilippPS: I've attached a Photo from a board which looks like the reference board. It contains a LM399 and a lot of trimmers which are labeled as follows:Vref8421100µA1mA10mA100mA1A10mV100mV1V10V100V0.999V ZeroA Zeroand 4x OffsetI can adjust for example the 1V trimmer to adjust the 1.0000 setting to 1.0000V but then the 0.5000 setting is not exact.

author: zaoka
author_rank: Frequent Contributor
timestamp: September 26, 2013, 01:24:30 pm
content: You have to email Hioki Japan, they sent me all schematics I asked for.Try this email: kkondo (AT) hioki.co.jp

author: e61_phil
author_rank: Frequent Contributor
timestamp: September 26, 2013, 06:33:47 pm
content: Ok, Thank youI've wrote an email. I will inform you what happens.I´ve attached the output voltage of the Hioki set up to 1.0000 and measured by an Agilent 34410A (6.5 digits). It takes almost 1.5h for the output to become stable and the last digits of the Agilent do not stand still. The last digits of the Agilent doesn't matter for an 4.5digit DC standard, but I hoped with the LM399 the output becomes stabler. (Yes, I know there is much between the LM399 and the output)

author: e61_phil
author_rank: Frequent Contributor
timestamp: October 07, 2013, 10:27:35 am
content: No response until today

author: macboy
author_rank: Super Contributor
timestamp: October 07, 2013, 03:43:27 pm
content: Have a look at the datasheet for LM399.Look at low frequency noise (given as a waveform over time). There is at least 10µV P-P noise over a several seconds/minutes. That's at least 1.5 ppm. Consider that the Hoiki and your meter each have a LM399, and each contributes 1.5 ppm of P-P noise/uncertainty in the reading displayed on the meter. That correlates well with what you are measuring, if you account for some additional noise and drift in other parts of the system.
Get to play with Spectrum Analyzer - Page 1
Forum section: electronics / testgear

author: tiofilo75
author_rank: Contributor
timestamp: October 07, 2013, 04:08:53 am
content: I'm excited I get to play with a spectrum analyzer for the first time tomorrow. I am taking a communications lab and we get an introduction tomorrow, I hope I don't screw it up. It's a HP8590A so Ill be looking at youtube videos to kind of get an idea how to use them. Does anyone know of any useful links on how to use them? Any tips that would be useful? Thanks.

author: kahvikello
author_rank: Newbie
timestamp: October 07, 2013, 05:56:03 am
content: How about thishttp://testrf.com/2010/spectrum-analyzer-tutorial/

author: tiofilo75
author_rank: Contributor
timestamp: October 07, 2013, 07:13:34 am
content: Sweet, Thanks.
Quasi-calibrating an old Hitachi-V223 - Page 1
Forum section: electronics / testgear

author: microbug
author_rank: Frequent Contributor
timestamp: October 06, 2013, 04:32:16 pm
content: I recently bought a Hitachi V-223 analog scope on eBay (£15 / $24, can you believe it?!), and after some cleaning up (contact cleaner on pots, alcohol on control panel) it seems to be working fine, though the horizontal gain is out of spec.As you can see from the pictures, I found the horizontal gain trimpot and I can tweak it to get either its internal reference square wave (.5v pk-pk) or an AD9850 module also from eBay to be spot on -but they do not match!If I get it accurate for the sine wave from the module (tested both @ 1MHz and 1KHz), it isn't accurate for the square wave. This isn't because they are two different ranges because the square wave is 1KHz and if I test the sine wave at the same frequency it is still out of cal.So which should I trust? I would place my bet on the module based on both what I've heard here andon this blog, but I'm a noob! - what is your opinion?

author: sync
author_rank: Frequent Contributor
timestamp: October 06, 2013, 04:39:13 pm
content: Don't trust the probe calibration signal. It's usually not build to have an accurate frequency and amplitude.

author: microbug
author_rank: Frequent Contributor
timestamp: October 06, 2013, 05:46:55 pm
content: OK - glad to see I was right
Teledyne LeCroy HDO4024 Teardown - Page 1
Forum section: electronics / testgear

author: BalticLab
author_rank: Regular Contributor
timestamp: October 04, 2013, 07:26:16 pm
content: Hey guys, I had a Teledyne LeCroy HDO4024 on my bench for a while now and decided to take it apart and share the inside with teh world. Here you go:https://baltic-lab.com/2013/10/look-inside-teledyne-lecroy-hdo4024/

author: marshallh
author_rank: Unknown
timestamp: October 04, 2013, 07:37:52 pm
content: Cool! only minor error is the PCIe signals are probably going to the middle FPGA (not asic) that collates channel sample data. (That LPC is probably power management/housekeeping or mmaaaybe PCIe bus arb)

author: BalticLab
author_rank: Regular Contributor
timestamp: October 04, 2013, 07:40:45 pm
content: Well, LeCroy confirmed that the center object is indeed the timing ASIC. From the wiring, most lane signals go to the NXP ARM. Who knows, after all I was just guessing.

author: TiN
author_rank: Super Contributor
timestamp: October 04, 2013, 08:08:17 pm
content: ThatNXP ARM7cannot handle PCIe by any means. It's just management/controlling slow stuff around.

author: BalticLab
author_rank: Regular Contributor
timestamp: October 04, 2013, 08:12:19 pm
content: I guess looking at the speed of the ARM excludes PCIe as option. Too bad I closed the box back up, maybe the traces just crossed paths coincidentally.

author: BalticLab
author_rank: Regular Contributor
timestamp: October 04, 2013, 08:22:22 pm
content: I guess it goes to the FPGA just above the ASIC in the center.

author: BalticLab
author_rank: Regular Contributor
timestamp: October 06, 2013, 02:10:08 pm
content: Hey guys, there were so many views on my teardown that I decided to make a teardown video. I think considering the fact that I didn't plan anything it went pretty well. I will have to find a solution to mount the camera instead of using my hand in the future though. And I of course made some critical errors, like identifying the differential buffers as ADCs and the actual ADCs as FPGAsBut Ah well, enjoy!
Calibrating a meter from single voltage - Page 1
Forum section: electronics / testgear

author: Harvs
author_rank: Super Contributor
timestamp: October 06, 2013, 01:47:51 am
content: I've got a 5V reference coming from Doug athttp://www.voltagestandard.com/that I'm hoping to cal my Escort 3146a to. It's a 5.5 digit bench meter that I bought some time ago for cheap because the calibration in it had been screwed and the owner couldn't work out how to fix it.Anyway, the challenge is, to cal this thing from the front panel (which is the only way I've worked out how) requires a voltages at 100mV, 1V, 10V, 100V and I can only guess 1000V.I'm quite happy just to leave the high voltage range where it is. It's close enough, and when I'm measuring over 100V I'd normally be doing it with a handheld DMM.So the 100mV and 1V I reckon I could get by building a resistive divider. Generally following the guidlines ofhttp://conradhoffman.com/mini_metro_lab.htmlThe 10V reference I think I would be best off using a capacitive doubler using a LTC1043.But the 100V reference has got me somewhat stumped. Any good ideas?

author: Galaxyrise
author_rank: Frequent Contributor
timestamp: October 06, 2013, 02:02:25 am
content: https://www.eevblog.com/forum/beginners/why-does-my-op-amp-circuit-need-a-capacitor/was about my approach to this problem.

author: tszaboo
author_rank: Super Contributor
timestamp: October 06, 2013, 02:12:50 am
content: Quote from: Galaxyrise on October 06, 2013, 02:02:25 amThat is actually a neat idea. I was going to suggest the LTC6090 (and some Vishay bulk metal foil resistor) which is brand new and can handle 140V, but the battery idea is just clever. I'm going to stole it.

author: Harvs
author_rank: Super Contributor
timestamp: October 06, 2013, 02:30:28 am
content: Neat easy solution. I'll probably do that.Was the 96V just 10x 9V batteries?

author: Harvs
author_rank: Super Contributor
timestamp: October 06, 2013, 02:46:25 am
content: Quote from: NANDBlog on October 06, 2013, 02:12:50 amActually that LTC6090 is a very cool device to. I'd looked around previously to build a "high" voltage source for automated calibration (of a product), but that's a really nice part at a quite reasonable price in comparison to others on the market.

author: Galaxyrise
author_rank: Frequent Contributor
timestamp: October 06, 2013, 03:58:56 am
content: Quote from: Harvs on October 06, 2013, 02:30:28 amThanksYes, that's 10x 9V batteries. Two six packs bought at a discount megastore.
RIGOL DS2072 - displaying pulse width trace - integral won't work - Page 1
Forum section: electronics / testgear

author: Circlotron
author_rank: Super Contributor
timestamp: October 04, 2013, 07:41:40 am
content: I want to have a trace that displays pulse width of a varying PWM signal. Using integral is no good because the signal swings from zero to +V not either side of zero so the integral trace ratchets off the page. What to do?

author: JDubU
author_rank: Frequent Contributor
timestamp: October 04, 2013, 05:03:21 pm
content: Integral with AC input coupling?Or you could level shift the scope ground to half of the logic level using a resistor divider.

author: Harvs
author_rank: Super Contributor
timestamp: October 05, 2013, 02:00:44 am
content: Depends a bit on what you're signal is, but you're right that the integral function integrates a signal across the length of time on the display. Where as, what you're trying to do is effectively low-pass the signal. As far as I know there is no function in the scope to do a tunable low pass filter, though simply turning on AC coupling then looking a the offset from zero is essentially that.Possibly your easiest option is to build an external low pass filter out of a resistor and cap (or couple of stages there of). Dave even had a video on doing that to make a PWM DAC.

author: Circlotron
author_rank: Super Contributor
timestamp: October 06, 2013, 11:31:12 am
content: Quote from: JDubU on October 04, 2013, 05:03:21 pmSecond one sounds like it might work.

author: Circlotron
author_rank: Super Contributor
timestamp: October 06, 2013, 11:33:11 am
content: Quote from: Harvs on October 05, 2013, 02:00:44 amYeah, sounds like the sensible approach to me.Was fiddling around looking for hi-tech solutions and overlooked the obvious.
eBay scope for $39 !!! hurry - Page 1
Forum section: electronics / testgear

author: zaoka
author_rank: Frequent Contributor
timestamp: October 05, 2013, 05:03:06 pm
content: Another great deal:http://www.ebay.com/itm/GoldStar-Oscilloscope-Model-OS-7020A-20-MHz-Clean-Unit-w-Operators-Manual-/141082135434?pt=BI_Oscilloscopes&hash=item20d9268b8a&autorefresh=true

author: c4757p
author_rank: Super Contributor
timestamp: October 05, 2013, 05:07:40 pm
content: $40 plus $18 shipping for 20 MHz? Pass...For low bandwidth scopes, my general rule is $1/MHz if you're patient, + 50% for desperation.

author: JoeO
author_rank: Frequent Contributor
timestamp: October 05, 2013, 07:45:46 pm
content: It is sold.

author: peter.mitchell
author_rank: Super Contributor
timestamp: October 06, 2013, 03:47:04 am
content: Quote from: c4757p on October 05, 2013, 05:07:40 pmWith the *only* $82 international shipping, it would have been the cheapest 20mhz scope on ebay australia for a long time

author: echen1024
author_rank: Super Contributor
timestamp: October 06, 2013, 03:50:40 am
content: The curse of the EEVBlog
Rigol DS1000E vs 1000CA - Page 1
Forum section: electronics / testgear

author: echen1024
author_rank: Super Contributor
timestamp: October 04, 2013, 02:16:31 pm
content: I was just browsing the Rigol 1000 series, and noticed the CA model. What's up with the near double price for the roughly similar features? Did this ever sell well? Also, what is it meant to replace?

author: clifford
author_rank: Regular Contributor
timestamp: October 05, 2013, 11:04:39 am
content: Never heard of the 1000CA series before and interestingly it is not linked via the menu on the RIGOL website (I can only find the DS1000B, DS1000D and DS1000E series there).But I was able to guess the right link:http://www.rigol.com/prodserv/DS1000CA/So according to this site it has double the sampling rate compared to the DS1000E and goes up to 300 MHz bandwidth. So I'd guess it is a 2-channel variation of the DS1000B series with a slightly better frontend so it goes to 300 MHz instead of the 200 MHz of the DS1000B scopes. It also has the low memory depth in common with the DS1000B series (16kPts on the DS1000B and only 10kPts on the DS1000CA, compared to 1MPts on the DS1000E and DS1000D series).

author: Hydrawerk
author_rank: Super Contributor
timestamp: October 05, 2013, 05:41:38 pm
content: DS1000CA has 2000 waveforms per second. Well, in 2010 it was an impressive number. But now it is not.
Wellzion T&M anyone got any?  - Page 1
Forum section: electronics / testgear

author: Fleetz
author_rank: Regular Contributor
timestamp: October 04, 2013, 01:59:20 am
content: Just wondering if anyone has had any experience with Wellzion equipment? Done a search here and doesn't get a mention.They seem to have a reasonable range of scopes, generators etc looking at a digital scope probably around the 100Mhz range and an arbitrary waveform generator at the moment. Looking at OWON, Rigol but Wellizion came up when I was doing my search. They don't look like they have much exposure?Regards,Fleetz

author: Fleetz
author_rank: Regular Contributor
timestamp: October 04, 2013, 11:06:33 pm
content: Think that answers my question. No one has come back with they have had experience or indeed knowledge of Wellzion.I can not find anyone handling it here in Australia or any reviews so don't feel being a pioneer and dip my toes in the water. OWON and Rigol seem to have a reasonable following here so a safer direction for me I think. Pity Wellizion seemed to have a reasonable range but without any other users, reviews or tear downs and no local support they are not likely to see light of day.Sorry should a posted a link in the first post so members can see what I am looking athttp://www.wellzion.com/Fleetz

author: sync
author_rank: Frequent Contributor
timestamp: October 05, 2013, 12:21:43 am
content: Their DSOs are from Siglent. Look at the pictures there is the Siglent label on it. The other stuff seems to be a mix from different manufactures.

author: echen1024
author_rank: Super Contributor
timestamp: October 05, 2013, 02:31:55 am
content: I see some Siglent DSO/Arb Gen's, possibly some yokogawa equipment. But yeah, stay away from this rebranded crap. You'll probably end up overpaying.
Tek TDS744A display issues  - Page 1
Forum section: electronics / testgear

author: madsci
author_rank: Regular Contributor
timestamp: October 04, 2013, 09:31:42 am
content: The image on the built in display on my TDS744A is "squashed". I'm quite happy using it with an external VGA monitor as I have for months now but I'd like to make it work right. It has passed SPC several times in a row without issue so I think I got a good one save for the shrunken image on the screen.Horizontal width is about half of normal and the vertical is a bit short as well. The issue is not intermittent.Other than that, the screen works very well. The color system seems to be fully operational, the display is bright with no burn in at all and the focus is excellent.There are internal adjustments but they appear only to be TR, brightness, contrast and H and V position. There are unfortunately no width adjustments so I'm wondering what I should look for when I get around to digging inside the CRT module. Is it the usual caps and such or is there a specific fault I should look into?

author: nctnico
author_rank: Super Contributor
timestamp: October 04, 2013, 05:22:24 pm
content: There are width and height adjustments; they aren't mentioned in the service manual. The vertical size is adjustable with a pot. The horizontal width is adjusted by an inductor which has be 'locked' with lacquer. There is a TDS520B component service manual with diagrams of a color CRT board BUT... there are several different types of color CRT boards around.Regarding your problem. Using the diagrams you may be able to find out where the problem is. If both horizontal and vertical are affected it may be the power supply. I'd check the 24V supply and reseat the cable between the display board and the CPU board.

author: madsci
author_rank: Regular Contributor
timestamp: October 04, 2013, 08:21:35 pm
content: Thanks!Now the fun part will be making said tests and or adjustments without the CPU board in place. The horizontal is out of spec far more than the vertical. In both the horizontal and the vertical, linearity is good with no noticeable pincushion.Since the horizontal drive peak current limiting inductor is locked in place, my first suspect would be the series cap right after the horizontal linearity inductor.+24 is apparently derived via a tap on the same transformer that feeds the +5.1V logic supply. Since it's group regulated and the CPU board is obviously happy, we can rule out regulator failures immediately. I'll verify solder joints, etc.

author: nctnico
author_rank: Super Contributor
timestamp: October 04, 2013, 08:41:09 pm
content: I'd still check the 24V rails before trying anything else. The other voltages are post regulated. The 24V wanders around a bit. Did you buy the scope this way or did it happen suddenly?

author: madsci
author_rank: Regular Contributor
timestamp: October 04, 2013, 09:31:14 pm
content: I bought it in this condition for quite a lot less than a fully working one would have cost. In fact it was the cheapest functioning (ie, turns on and doesn't have acquisition board faults) one on eBay at the time.
Need user manual for Protek Z9218 - Page 1
Forum section: electronics / testgear

author: VIPR
author_rank: Contributor
timestamp: October 04, 2013, 12:46:46 am
content: I have searched quite extensively on the web for a user manual for my Protek Z9218 LCR meter but can't seem to find one anywhere. The company is no longer in business so I have no chance at getting one from them. I'm asking for the help of the community on the forum here if you have a copy (preferably digital) or know where to get one I would be very grateful if you would help me get access to it.Thanks.
NAPA Multimeter - Page 1
Forum section: electronics / testgear

author: crt
author_rank: Regular Contributor
timestamp: October 01, 2013, 02:51:34 pm
content: Automotive DMM, I just buy it for $30Heres inside pictureReading is slow, about 3 reading/2 secondand look at those Variable Resistor (too much) and i accidentally turn one of them because i thought a screw

author: Robomeds
author_rank: Frequent Contributor
timestamp: October 01, 2013, 06:16:43 pm
content: Interesting. It's a CEM meter. I recently took a look at one almost the same as the other Napa CEM based meter, the one without auto specific functions. The other one had some things I quite liked. It used two HRC fuses. That one appears to have lesser fuses. Note that unlike the Extech EX505 Dave tested, this one has no PCB on the outside of the input jacks. Mine had the same thing. Also note they have put safety components on both sides of the board to relieve some of the over crowding Dave mentioned. The physical build of the meter feels very nice in the hand but the range switch felt really lousy, stiff yet imprecise. What I found was the stiffness was not due to the detent mechanism which actually felt good. It was the sliding contacts that add a lot of friction and make things feel bad. I used some contact of the grease like what Fluke uses on the contacts. Things felt much better after that.Sadly these meters are very slow and the accuracy specs, for what it's worth aren't impressive. Pity because on the outside the look and feel good.

author: retiredcaps
author_rank: Super Contributor
timestamp: October 01, 2013, 07:52:47 pm
content: Thanks for sharing the pictures.The OEM is CEM (AT-9965)http://www.cem-instruments.com/en/pro/pro-556.htmlhttp://www.cem-instruments.com/en/UploadFile/20110113095609513.jpgThe main IC ishttp://www.cyrustek.com.tw/spec/ES51962.pdfOn page 19, it says the ZI, AZ, INT and DINT is 100ms, 150ms, 100ms, and 400ms respectively for voltage measurement in high resolution mode. So it takes 750ms for one cycle which implies roughly 1.33 readings/sec. This might explain why the multimeter is so slow in displaying readings.

author: crt
author_rank: Regular Contributor
timestamp: October 02, 2013, 04:43:57 am
content: Quote from: Robomeds on October 01, 2013, 06:16:43 pmagree with youQuote from: retiredcaps on October 01, 2013, 07:52:47 pmIs there any way to change them to high speed ?

author: retiredcaps
author_rank: Super Contributor
timestamp: October 02, 2013, 08:13:05 am
content: Quote from: crt on October 02, 2013, 04:43:57 amThe high speed mode is for the bargraph according to datasheet. It is 1/10th cycle time compared to the high resolution mode so that implies 13/sec update.Sometime in the future I will be getting a Cyrustek multimeter will similar specs (750ms cycle) so I will see firsthand how slow it is.

author: crt
author_rank: Regular Contributor
timestamp: October 03, 2013, 01:25:10 am
content: Quote from: retiredcaps on October 02, 2013, 08:13:05 amMaybe not to slow, but i just don't like itespecially when i use as RPM meter
SCPI over LAN with HP Infinium 54820A - Page 1
Forum section: electronics / testgear

author: lance666
author_rank: Newbie
timestamp: October 01, 2013, 05:26:11 pm
content: In the past I've used SCPI over LAN with Agilent scopes by connecting to ports 5024 and 5025. I have access to an old HP Infinium 54820A which has a LAN card. The scope connects to the network (I can see it from the router). But it doesn't respond on ports 5024 or 5025. Anyone know if these scopes can be controlled by SCPI over the LAN port, or is only GPIB supported? And if it should work over LAN any idea why it isn't listening on these ports? Is there some magic setting to enable it that I've not discovered?Thanks.

author: free_electron
author_rank: Super Contributor
timestamp: October 01, 2013, 05:29:36 pm
content: it depends on the firmware version. Lan control is there if the machine has 4.xx or later.Agilent has a document describing what versions have the LAN.

author: lance666
author_rank: Newbie
timestamp: October 01, 2013, 06:21:49 pm
content: Ah, the scope says the software revision is A.03.50, so that presumably explains why it isn't responding. Is the firmware user-upgradable, and if so any idea where I'd find a more recent version (hopefully >= 4.xx)?Thanks
Power supply unstable except when active load attached (but not enabled) - Page 1
Forum section: electronics / testgear

author: uoficowboy
author_rank: Regular Contributor
timestamp: October 02, 2013, 02:11:31 am
content: I have a Shenzhen Mastech HY3003D-2 that is acting... funny. If you measure the output with a scope, it has about a 10V peak to peak sawtooth waveform at about 8.5KHz (on top of the DC). However, if I attach a active load, specifically a BK Precision 8500 to it, the oscillation stops and it acts like a normal supply - it handles loads gracefully as well. But if I connect a resistor to it, it just oscillates. Further, the load stabilizes both channels at the same time. As in, even though the load is only connected to one channel, both channels stabilize (and they're set to be independent). I'm measuring this with a grounded scope. I've tried grounding either side of the output, and no change.Anybody have any ideas as to what is going on here?

author: Jay_Diddy_B
author_rank: Super Contributor
timestamp: October 02, 2013, 02:21:25 am
content: Hi,The load probably has a RC network connected across the input.Try connecting an electrolytic capacitor across the output of your power supply and the load resistor. If the removes the oscillation open up the load and look for a loose capacitor/bad joint on the output capacitor.The output capacitor is required for control loop stability.Good luck !!Jay_Diddy_B

author: uoficowboy
author_rank: Regular Contributor
timestamp: October 02, 2013, 02:58:41 am
content: Quote from: Jay_Diddy_B on October 02, 2013, 02:21:25 amLooks like you're right - it has a 470uf capacitor that measures out as about 100nf on the output. Ouch.Oddly enough, only one channel has a shrunken capacitor. The capacitor on the other channel (that did not exhibit the problem as much, but still exhibited it) measures out at about 490uf. But I suspect the ESR is horrendous or something similar, so I'll replace it anyways.Thanks for the help!
UT81B - Page 1
Forum section: electronics / testgear

author: R_G_B_
author_rank: Frequent Contributor
timestamp: September 30, 2013, 08:55:56 am
content: I have a ut81B scope meter and was wondering if it would be possible to mod it slightly just to improve the bandwidth slightly so it can at least show a 1Mhz sqaure wave. The divice has what seems like a master slave configuration e.gThe LPC 2138 drives the cyclone 2 FPGA which drives the display and is runs off a 12MHz crystal. The LPC arm chip is running of its on own internal clock.The ADC is a 98283. There are 3 version of this ADC 50mhz 80mhz and 100mhz with identical connections.Question is if I double the clock frequency and the ADC to 100Mhz does this make the ut81B the same spec as the ut81C? obviously it has a software change to allow the time base to go to 50ns. But nothing more than that.The low noise analogue amplifier at the front end is onlt 50Mhz analogue bandiwthwhich may be causing the problems attentuation at high frequency causing the pulse shape to to have distortion.Also the circuits are very noisy.Is there any way to reverse engineer the FPGA and LPC software?Something to do a hack project.R_G_B_

author: Bored@Work
author_rank: Super Contributor
timestamp: September 30, 2013, 10:48:21 am
content: Why do you think modifying a 8 MHz BW, 40MS/s "oscilloscope" is needed to view a 1 MHz square wave?

author: dr_p
author_rank: Frequent Contributor
timestamp: September 30, 2013, 12:48:49 pm
content: The UT81B has a bandwidth of 8MHz so it's perfectly capable of displaying a 1MHz square wave(the 3rd harmonic is 7Mhz). Inherethere are photos of the scope doing these measurements.So I don't understand what you want to hack it for.

author: R_G_B_
author_rank: Frequent Contributor
timestamp: September 30, 2013, 10:16:30 pm
content: The Ut81b shows a lot of distortion on my scope at 1mhz when set to frequency measurement. Would be interesting to see where its limitations are by changing a few components. According to The ADC data sheet it has an analogue bandwidth of up to 400Mhz.

author: Wytnucls
author_rank: Super Contributor
timestamp: October 01, 2013, 03:12:59 am
content: There is a UT81C version, with higher specs.http://www.ebay.com/itm/UNI-T-Handheld-Digital-Multimeter-3999Counts-16MHz-Multimeter-UT81C-/380647788963?pt=LH_DefaultDomain_0&hash=item58a06051a3

author: R_G_B_
author_rank: Frequent Contributor
timestamp: October 01, 2013, 07:00:56 am
content: Yes the specs for the scope are 16MHz analogue and width double that of the ut81b.So did they just double the crystal clock from 12MHz to 24MHz and the ADC to 100MHzJust altering the software to 50ns time base? Not sure about the amplifier though?

author: R_G_B_
author_rank: Frequent Contributor
timestamp: October 01, 2013, 07:32:20 am
content: Be interesting if someone had a UT81C so that we could see the difference in components used between the two to give the different bandwidth.
New Rigol Products - Page 1
Forum section: electronics / testgear

author: echen1024
author_rank: Super Contributor
timestamp: September 30, 2013, 09:08:52 pm
content: New product categories in addition to the typical new products, with pricing on rigol.cn. You will need to select the China region.Expected:DS2072A: Base price, 6800 RMBDG1000Z Function gen's: Base price for 30Mhz: 3880RMB****NEW PRODUCT CATEGORIES****M300 Data Acquisition/Switch system. Not really sure what this if for. Base price, 9554 RMBNew 800/1000 Series power supplies (811, 821, 1116): Not sure if new product, or old product. Seems to open the 2013 datasheet. No pricing available yet.And perhaps the most interesting...Rigol DSG3000 Signal Generators. 9kHz to 3 GHZ for base model, 55,735 RMB, -130dBm to +13dBm.Hope to see these new products being reviewed by Dave soon!
Agilent U1242B First Impressions - Page 1
Forum section: electronics / testgear

author: ndzied1
author_rank: Contributor
timestamp: September 30, 2013, 04:59:59 pm
content: Been over 15 years since I got a new meter and wasn't trusting the old one which is a really bad feeling.Watched a lot of reviews, mostly from Dave and had a certain budget to stay within. I zeroed in on Agilent U1242B for a few reasons:Wanted something new and Fluke 87V was out of my budgetUse 4-20mA quite a bit and liked the thought of the 0-100% display for 4-20mAThought the switch count function sounded neatLiked the idea of the serial interface although didn't purchase the USB or Bluetooth adapter yetLiked the internal temperature display even if it isn't very accurateDon't care about "slow" response on the continuity checkI purchased the unit from Newark.com (Element 14) and it arrived in a few days.In the box is the meter, basic insulated lead set, quick start guide, calibration certificate and...the required plastic adapter to use the USB or Bluetooth serial interfaces. I read several places that people had to purchase this separately and so it was nice to see it there.So far everything is as expected except for two things:When you turn off the beep via the setup menu, the thing makes a very wanky noise when you turn it on. Not sure if anything is being damaged but it just sounds wrong.A big thumbs down for the flip down portion of the tilting bale. The normal bale operation folds out and back just fine. There is a short piece on the end of the bale that is supposed to fold down for a lower sitting angle. This thing falls off 75% of the time when I try to bend it over.a true piece of ****!I tried to attache a picture of the part of the bale I'm talking about but this is my first post here so not sure how it will come through.

author: nanofrog
author_rank: Super Contributor
timestamp: September 30, 2013, 06:16:23 pm
content: Contact Agilent.They'll likely send you a new tilting bale for it instead of having to ship the entire unit back (I have a U1252B, and the bale stays on <both parts>; it uses the same dk. gray & orange meter enclosure as yours).

author: tszaboo
author_rank: Super Contributor
timestamp: September 30, 2013, 07:51:38 pm
content: I also got my hands on one not long ago, with BT. The BT reach is a bit short, it was failing 5m long or so. And the feeling of the meter is definitely different from Fluke. But to be honest I prefer this over the flukes in the same price range at the moment. The long term will tell if it is worth it or not.BTW the title has too many 1-s.
Agilent 34401A input terminal  - Page 1
Forum section: electronics / testgear

author: pgross
author_rank: Contributor
timestamp: September 27, 2013, 09:45:41 am
content: Hey forum,I discovered that the input terminal plastic of my Agilent 34401A multimeter is cracked atthe V, Ohms jack. The electrical connection is fine, but the copper terminal is loose, andwhen I opened the instrument some small red cracked plastic parts fell off.Does anybody know if it’s possible to replace the plastic block alone, without desolderingthe terminal off the board?The Agilent part number (34401-62121) is a complete terminal assembly. But as far as I cansee, the block itself is a sandwich construction with two molded plastic halves fitted togetherover the copper terminals. The plastic seems to be brittle - it puzzles me, because the meteris only six years old!I’ll appreciate any help.Best RegardsPeter

author: babysitter
author_rank: Frequent Contributor
timestamp: September 30, 2013, 08:43:23 am
content: ... sounds like the front fell off!

author: pgross
author_rank: Contributor
timestamp: September 30, 2013, 01:02:06 pm
content: Ahh, well no drama at allBut the outer parts of the V, Ohms is cracked and the copper terminal is loose.I have ordered a new terminal block from Agilent. It should be possible to remove the outer plastic part - without desoldering.RegardsPeter
Rigol Handheld Multimeter... - Page 1
Forum section: electronics / testgear

author: echen1024
author_rank: Super Contributor
timestamp: September 29, 2013, 03:27:00 am
content: I was wondering if Rigol had any plans to produce something like this. I'm expecting EXCELLENT bang for the buck. I would be very interested in something like this. Anyone know if something like this is in the pipeline...*nudgenudewinkwink* @ Rigol

author: junggwok
author_rank: Contributor
timestamp: September 29, 2013, 04:23:55 am
content: IMHO, I doubt it very much. I mean look at Agilent handheld multimeters. Agilent has a huge range, but I don't know anyone who use multimeter (professionally or on daily basis) uses even an Agilent meter. I mean I work in the industry, everyone I know inside and outside of work, uses Fluke. (including myself, I do have a number of Flukes and Agilents and even original Escort meters which a lot of Agilent handheld meters are based upon). Everywhere you see, it is always Fluke 87v, 287, 289 etc... Kinda annoying actually. I don't think Rigol will go into this segment of the market, it is just not logical. Rigol does make some interesting and pretty good instruments, even a 6.5 digit bench multimeter and their quality is only getting better. They're releasing RF signal generators, but handheld multimeters especially when it comes to an electrician's work, (life depends on it). Rigol ....... no bloody way.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: September 29, 2013, 09:32:59 am
content: Rigol would be nuts to go into this very crowded marketplace UNLESS they came up with something really different to make them stand out.

author: Hydrawerk
author_rank: Super Contributor
timestamp: September 29, 2013, 01:06:52 pm
content: Oh, there are so many cheap multimeters in markets...
Rigol DS2000 Probes - Page 1
Forum section: electronics / testgear

author: JDubU
author_rank: Frequent Contributor
timestamp: September 27, 2013, 12:42:10 am
content: Is anyone else having trouble with the RP3300A probe hook not retracting reliably into its shroud?For me, the hooks tend to twist slightly and catch on the side of the shroud and has to be fussed with to get it to retract. Very annoying!Ideas?

author: leafi
author_rank: Regular Contributor
timestamp: September 27, 2013, 02:46:22 am
content: Yes I have exactly the same problem. It is VERY annoying!

author: clifford
author_rank: Regular Contributor
timestamp: September 27, 2013, 11:59:14 am
content: Same here. I'm not sure if I'm getting used to it or if it became better over time..

author: iceisfun
author_rank: Regular Contributor
timestamp: September 27, 2013, 04:47:38 pm
content: Mine don't have that problem, however they don't stick on the probe very well

author: Spike101
author_rank: Contributor
timestamp: September 27, 2013, 04:54:20 pm
content: Quote from: iceisfun on September 27, 2013, 04:47:38 pmMaybe, you have to push them onto the probe a bit harder. You should hear a "click", once they are well attached.At first, i was also disappointed, but then i realized, that i was too gentle with them.

author: Galaxyrise
author_rank: Frequent Contributor
timestamp: September 27, 2013, 04:57:13 pm
content: Quote from: JDubU on September 27, 2013, 12:42:10 amMine don't twist as they retract, but I did manage to bend one of mine a little by hanging the probe off of it such that it hung sideways off the clip. Once bent, it didn't retract properly. I straightened the clip with needle nose pliers and it's been fine since.Quote from: iceisfun on September 27, 2013, 04:47:38 pmThere's a plastic ridge between the ground and probe tip that the clip snaps over. The first time or two you attach the clip, it takes quite a bit of force to get over that. Like Spike says, you probably just didn't push hard enough.

author: Hydrawerk
author_rank: Super Contributor
timestamp: September 27, 2013, 05:42:09 pm
content: My DSOX2002A probes are OK, but they are only 1:10.

author: Unknown
author_rank: Unknown
timestamp: September 27, 2013, 07:27:45 pm
content: That's one less extra switch to degrade performance or accidentally switch. Get some cheap 1:1, or even switchable, probes for the low frequency stuff where you might use a 1x probe.

author: JDubU
author_rank: Frequent Contributor
timestamp: September 28, 2013, 06:24:49 pm
content: Quote from: clifford on September 27, 2013, 11:59:14 amI think you are right.I just spent a bit of time cycling the probe hooks and they are definitely getting better.The hooks are slowly digging a shallow bevel in the surrounding plastic, reducing the hangup problem.