EEVblog #880 - Mailbag - Page 1
Forum section: electronics / general

author: EEVblog
author_rank: Unknown
timestamp: May 16, 2016, 11:54:33 pm
content: Mailbag MondayTeardown bonanzaSPOILERS:LCD's and CCD sensor under the Tagarno microscopeThe Aoyue3D Ritocco 3D shaping , cutting and finishing toolhttp://www.aoyue3d.com/amazon1980's multimeters (Fluke ripoff)Wandel & Goltermann optical attenuatorCheap mains energy meter teardownDTV TV tuner teardownWayback Wednesday material, a collection of the Cyclopedia Of Applied ElectricityIntroducing TeirnanRadio Shack calulator and diary teardownsDodgy ebay industrial light controllers

author: iamdarkyoshi
author_rank: Frequent Contributor
timestamp: May 17, 2016, 12:51:59 am
content: Those old multimeters? Yeah I have some under yet another label

author: Razor512
author_rank: Regular Contributor
timestamp: May 17, 2016, 12:53:06 am
content: I would love to see various generation of CCD and CMOS sensors under a good amount of magnification.I took apart a few cameras a while back, mainly for some capacitors, card slots, and the backlights.Full size:

author: n3vti
author_rank: Contributor
timestamp: May 17, 2016, 03:08:41 am
content: Holy crap! I remember the RadioShack shopping calculator, and I used to own the black organizer! Ah, the quirkiness thatiswas RadioShack back then...Speaking of that, sorry if I haven't been on in a while. I just got promoted to a manager of a store, so now I just might be able to get some (decent) equipment! Because of the long hours (and longer drive), I won't be on as often.

author: bktemp
author_rank: Super Contributor
timestamp: May 17, 2016, 06:27:19 am
content: The lamp ballasts actually look pretty decent. They are Osram PT VIP 03 MID.

author: Brumby
author_rank: Unknown
timestamp: May 17, 2016, 08:20:31 am
content: What's wrong with this picture?

author: bktemp
author_rank: Super Contributor
timestamp: May 17, 2016, 08:46:37 am
content: Quote from: Brumby on May 17, 2016, 08:20:31 amThere is no Vol 3, but Vol 8?

author: dexters_lab
author_rank: Unknown
timestamp: May 17, 2016, 09:35:43 am
content: hehe, i'll hold my hands up to electronic organisershad a few over the years, Casio SF-4000, PalmPilot Proi also had an Apple MessagePad 110

author: Muttley Snickers
author_rank: Unknown
timestamp: May 17, 2016, 10:34:36 am
content: Quote from: bktemp on May 17, 2016, 08:46:37 amIt was on one of the pages shown in the video declaring 8 volumes and I sent Dave a link earlier to a US Ebay listing specifically for volume 3 but the listing states they may not ship to AUS and he may not want it anyway. I realised afterwards being slightly blinded by what was missing rather than the realisation of what he did have.

author: Fungus
author_rank: Super Contributor
timestamp: May 17, 2016, 11:43:42 am
content: Quote from: bktemp on May 17, 2016, 08:46:37 amVolume III was borrowed by the missus to press some flowers....?

author: nitro2k01
author_rank: Frequent Contributor
timestamp: May 17, 2016, 12:11:21 pm
content: Oh look, yet another bodge! (On the PSU of the set top box.) Guess they didn't need a negative rail and wanted to make assembly simpler.

author: nitro2k01
author_rank: Frequent Contributor
timestamp: May 17, 2016, 12:53:06 pm
content: I think what happened on the lighting PSU was that the transistor touched the plastic film capacitor and melted it and shorted internally. A temperature that might be fine for the transistor could be deadly for the cap, and the exact alignment (whether they touch or not) could be what makes the PSU work or fail.

author: Fungus
author_rank: Super Contributor
timestamp: May 17, 2016, 01:21:30 pm
content: Quote from: nitro2k01 on May 17, 2016, 12:53:06 pmI'm thinking it's more like:a) The PSU designer did a decent job of making a PSU for some combination of price and ambient conditions.b) The PSUs were then bought by a disco light designer who doesn't read datasheets and was all, "Airflow? We don't need no stinkin' airflow!"c) ...this video.

author: sean0118
author_rank: Frequent Contributor
timestamp: May 17, 2016, 01:23:51 pm
content: Quote from: nitro2k01 on May 17, 2016, 12:53:06 pmMight be possible? But it's weird that they added such a large heatsink to the output transistor/diode which is probably just a boost converter.I think the four 19N20C mosfets are being used for input rectification (see link), I thought that would still require a fairly large heatsink?http://www.thetaeng.com/FETBridge.htm

author: Fungus
author_rank: Super Contributor
timestamp: May 17, 2016, 01:31:35 pm
content: Quote from: sean0118 on May 17, 2016, 01:23:51 pmMaybe.Quote from: sean0118 on May 17, 2016, 01:23:51 pmNope. A fully-turned-on MOSFET has very little voltage drop so hardly any Watts are dissipated.

author: bktemp
author_rank: Super Contributor
timestamp: May 17, 2016, 01:37:46 pm
content: Quote from: sean0118 on May 17, 2016, 01:23:51 pmI think Dave swapped the input and output connectors.Osram PT VIP 03 MID seems to be a HID ballast optimized for projection lamps. It even has a UART connection on the control board for controlling the lamp! The transformer next to the output is most likely the ignition transformer (insulated wire, multiple sections on the bobbin). The H-bridge probably generates a low frequency squarewave for the lamp. So it has almost no switching losses and only moderate conduction losses. The mosfet on the heatsink instead is probably used as buck converter for generating a constant current. Because it converts the rectified mains voltage into a lower voltage, it has quite high switching losses.

author: Towger
author_rank: Super Contributor
timestamp: May 17, 2016, 05:09:06 pm
content: Quote from: Brumby on May 17, 2016, 08:20:31 amThey are in the wrong order and volume 3 is missing.So much for my thoughs that Dave was the product if the Christian Brother education system or similar organisation.

author: gregallenwarner
author_rank: Regular Contributor
timestamp: May 17, 2016, 06:06:42 pm
content: I've noticed when tearing down multimeters, Dave always jokingly mocks the "crappy" transistor testers found on the cheap ones. Forgive my ignorance, maybe I haven't been around long enough to know why this is, but can anyone tell me for my own edification, why does Dave regard the transistor testers so poorly?

author: iamdarkyoshi
author_rank: Frequent Contributor
timestamp: May 17, 2016, 06:40:51 pm
content: Quote from: gregallenwarner on May 17, 2016, 06:06:42 pmIt seems to just be an unneeded feature added to cheap meters to make them look fancy and more feature packed.

author: bitwelder
author_rank: Super Contributor
timestamp: May 18, 2016, 05:27:08 am
content: At 23:05 the name of Nicola Tesla was listed among the 'authorities consulted' (which may have given his input on the foreword paragraph on 'transmitting electricity without wires' read by Dave)

author: HKJ
author_rank: Super Contributor
timestamp: May 18, 2016, 06:20:23 am
content: Quote from: gregallenwarner on May 17, 2016, 06:06:42 pmOne point may be that they are not needed, but more important is isolation distance. If you place a finger over the transistor socket the distance to the metal inside is less than a mm, compare that to the isolation at the test probes. Due to this a transistor tester will usual prevent any CAT rating, except the fake ones.

author: sean0118
author_rank: Frequent Contributor
timestamp: May 18, 2016, 10:19:36 am
content: Quote from: Fungus on May 17, 2016, 01:31:35 pmBut you don't know how many amps are running through them? Even at 3A these would be ~90C above ambient, unless I'm mistaken?Quote from: bktemp on May 17, 2016, 01:37:46 pmYeah that sort of makes sense, I was going off the letter which said 60VAC in and 300VDC out (Are there lights that require 300VDC?).I thought that transformer with the split bobbin was actually a common mode choke to filter the input AC.If the side with the heatsink is the input, where is the rectifier? Unless the boards DC input AC output?Anyway, still not closer to why the mosfets died, maybe the lamps just pull too much current?

author: Fungus
author_rank: Super Contributor
timestamp: May 18, 2016, 11:52:40 am
content: Quote from: gregallenwarner on May 17, 2016, 06:06:42 pma) They're uselessbut mainly:b) They're a sure sign of a crap multimeter. When you see a transistor tester you know you're in for a laugh if you open up the meter and look inside.

author: Fungus
author_rank: Super Contributor
timestamp: May 18, 2016, 12:14:03 pm
content: Quote from: sean0118 on May 18, 2016, 10:19:36 amLet's see:http://datasheet.octopart.com/FQP19N20-Fairchild-datasheet-87852.pdfRds(on) is 0.12 Ohms - higher than I expected for a MOSFET.Let's do the math then: At 3A the voltage drop across them is 0.36V. 0.36V at 3A is a bit more than 1W of power dissipation.Wikipediasays"When a TO-220 package is used without a heatsink the heatsink-to-ambient thermal resistance in air for a TO-220 package is approximately 70 °C/W", so ... 90°C is in the ballpark, yes.The datasheet says their operating temperature is up to 150°C so they'll be OK with that dissipation in open air. I guess it's all down to the airflow inside the lamp but you're probably right; those particular MOSFETs need heatsinks.

author: bktemp
author_rank: Super Contributor
timestamp: May 18, 2016, 12:22:43 pm
content: Quote from: Fungus on May 18, 2016, 12:14:03 pmIn a h-bridge only half of the mosfets are active at the same time, so the avarage power power dissipation is 0.5W per mosfet. That's ok without a heatsink.I can not find any datasheet or other informating for the ballast or the lamps.Here is the current model:http://www.osram.com/osram_com/products/electronics/electronic-control-gears-for-specialty-lighting/ecg-for-projection/index.jspThe ignition transformer is completely potted with the output wires attached.PT VIP 03 MID seems to be mainly being used in video projectors. Typically there is a PFC on the main power supply with a 350-400Vdc output going to the lamp ballast.Maybe the ballast requires forced air cooling, beause is it anyway necessary for the lamp.

author: sean0118
author_rank: Frequent Contributor
timestamp: May 18, 2016, 01:25:00 pm
content: Quote from: bktemp on May 18, 2016, 12:22:43 pmThat's true and I did not think of that! ...But they wouldn't last at 6A.

author: jitter
author_rank: Frequent Contributor
timestamp: May 20, 2016, 06:31:51 pm
content: When I saw the PE-747R I thought that it looked familiar.Under the Dynatek brand I have a 9020a that I bought in 1997. Though not yet CAT-rated, and lacking the input protection we would take for granted nowadays (it does have HRC fuses), I think it's a pretty good meter (despite the presence of a transistor tester). Tear downhere.

author: NVX
author_rank: Newbie
timestamp: May 21, 2016, 11:54:22 am
content: The IC with the number rubbed off on the plug in power meter is a Cirrus Logic CS5460Ahttps://www.cirrus.com/en/pubs/proDatasheet/CS5460A_F5.pdf- note this is not the slightly fancier pin-compatible replacements for this part CS5461A or CS5463, the latter of which has in-built line frequency measuring on the IC although showing the mains frequency is a feature of the power meter so the mains frequency detecting so this must be done on the chip on board blob.At least this is the case for the unit I have and reverse engineered (I searched by package for power metering ICs and compared pinouts, then got talking to it via its SPI interface.~Tiernan (But not the one in the video!)

author: SA007
author_rank: Newbie
timestamp: May 22, 2016, 07:59:54 pm
content: The chip with the rubber-off numbers int he plug power meter is probably a clone of the Analog Devices ADE7755.Used extensively in basic, only kW/kWh meters, and therefore there are a few copies of it floating around.The original is quite a nice chip, i have tested devices with a known clone in it and they performed roughly identical.So it is probably a easy chip to clone.I am missing calibration options/pads, this is usually done by solder pads to bridge a couple of resitors in path of the voltage measurement.It could be in high-resolution mode and calibrated in the software in the blob next to the lcd, but i doubt that.As for the capacitive dropper, that is the default design used in electricity meters, nothing new there.Regulations state that they must be double insulated, and to measure the shunt (which is in line with the phase) needs to be to the ground of the measurement chip.So your electronics can't be isolated, the device must be, so why add a isolated power supply, it is just more expensive.

author: photon
author_rank: Frequent Contributor
timestamp: May 22, 2016, 10:34:12 pm
content: Quote from: Brumby on May 17, 2016, 08:20:31 amI am an amateur collector of old technical books and Dave's mailbag pointed out this treatise not in my collection. Thanks Dave.Though I do buy the old books, I am highly allergic to them. So I always look for a PDF. Surprisingly, I found the complete collection of these volumes in free downloadable PDF's. Go herehttps://archive.organd search for "cyclopedia of applied electricity".

author: rsjsouza
author_rank: Super Contributor
timestamp: May 25, 2016, 07:34:07 pm
content: Quote from: Fungus on May 18, 2016, 11:52:40 amI don't disagree... The DMMs usually measure the transistor's hFE(DC current gain), which greatly varies with the applied bias on its terminals and the internal transistor construction (power, general purpose, RF, switching, etc.). If you know the tester's limitations, it becomes clear they are somewhat useful for a quick good/no-good check, though.Quote from: Fungus on May 18, 2016, 11:52:40 amNot quite. I have two Radioshack meters (2200087and2200039) where the hFEtest outlet is enclosed behind a plastic shield. The construction is reasonably solid.

author: rrinker
author_rank: Super Contributor
timestamp: May 25, 2016, 11:15:27 pm
content: Interesting, I wonder who the OEM is for that Rat Shack meter. Also had to LOL at the box label - "if you have a question about the features of this meter, just as a Radio Shack sales associate" The last person working for Radio Shack that could answer technical questions on multimeters (at least in the US) quit working there around 1986 (not so coincidently when I quit working there)

author: djacobow
author_rank: Super Contributor
timestamp: May 25, 2016, 11:29:14 pm
content: Regarding that PE-747R meter, I have a CIE-branded meter (8007) that is 100% identical. I bought it new in 1992 or so and it has worked well and is still in spec today. Because I have Fluke and other better meters now, I gave it to my little boy to play with, but I still often grab this one because the "toy" is in the house rather than the workshop. It works fine.

author: Neilm
author_rank: Super Contributor
timestamp: May 26, 2016, 06:58:43 pm
content: Quote from: Fungus on May 18, 2016, 11:52:40 amThey were usually found on cheap meters that didn't meet IEC61010. The reason being that meters that DID meet it, realised that transistor testers are connected to the 0V of the meter, which is also connected to the negative terminal. So if someone left a lead in it connected to the mains and touches the transistor will result in a shock. The latest version of 61010 specifically addresses this possibility. The earlier version simply hinted at it.

author: Hsimah
author_rank: Newbie
timestamp: June 01, 2016, 01:13:57 pm
content: Hi!Where is the tear down of the E-Toll Tag?I am unable to locate it on the EEVblog2Thanks

author: michelinux
author_rank: Contributor
timestamp: November 13, 2016, 10:46:35 pm
content: Ritocco: Italian languageIt means: "touch up", "retouch".http://it.bab.la/dizionario/italiano-inglese/ritocco

author: nerone
author_rank: Newbie
timestamp: December 06, 2018, 06:58:41 pm
content: Hi,Sorry for replying on a very old post, but I would really like to see how the e-tag teardown we have exactly the same model in Sweden and always thought it was some sort of RFID. Anybody know what happened to that video on eevblog2? Can't find ithttps://youtu.be/5bWEiyx6Bns?t=515Kind regards