- Tektronics THS720 scope display issues... - 3 Updates
- Scope power - 9 Updates
- What happens if you exceed the wattage of a transmitter antenna - 1 Update
| John Robertson <spam@flippers.com>: Mar 26 10:34PM -0700 A friend of mine in AU just asked me about "Tektronix THS720 handheld digital oscilloscope. As you can see in the attached photo, the LCD module is starting to go bad. Research indicates that the problem is likely due to the polarizer films deteriorating, and they can be replaced" Anyone have any other suggestions? The image in the photo showed a clear image, just fading on part of it. I suggested the inverter be checked, but am no expert on these units. Thanks! John :-#)# |
| "ohg...@gmail.com" <ohger1s@gmail.com>: Mar 27 07:44AM -0700 On Saturday, March 27, 2021 at 1:35:46 AM UTC-4, John Robertson wrote: > but am no expert on these units. > Thanks! > John :-#)# Any way to post a pic John? I have that model and would be interested in seeing the issue. |
| John Robertson <spam@flippers.com>: Mar 27 09:27AM -0700 >> Thanks! >> John :-#)# > Any way to post a pic John? I have that model and would be interested in seeing the issue. Yes, of course - here is a link to the image he sent me. https://www.flippers.com/images/delete/Tektronix_THS270.JPG I'm sure he will appreciate any advice, he replied to me: "Yes the display is illuminated by a small Cold Cathode Fluorescent Lamp which is working normally. The problem is that the centre area of the display is going darker and darker while the perimeter is still OK. I'll keep looking for info about polarizer film...." Thanks! John :-#)# -- (Please post followups or tech inquiries to the USENET newsgroup) John's Jukes Ltd. MOVED to #7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3 (604)872-5757 (Pinballs, Jukes, Video Games) www.flippers.com "Old pinballers never die, they just flip out." |
| "Tom Del Rosso" <fizzbintuesday@that-google-mail-domain.com>: Mar 26 05:51PM -0400 Why is it still necessary to worry about probing a floating ground? Most digital scopes have power requirements like high-end laptops, so why can't they have a battery option? They all have plastic cases, so why can't they have isolated supplies and no earth connection? -- Defund the Thought Police |
| Fox's Mercantile <jdangus@att.net>: Mar 26 04:56PM -0500 On 3/26/21 4:51 PM, Tom Del Rosso wrote: > They all have plastic cases, so why can't they have isolated supplies > and no earth connection? Because ungrounded equipment is always a bad idea. -- "I am a river to my people." Jeff-1.0 WA6FWi http:foxsmercantile.com |
| Phil Allison <pallison49@gmail.com>: Mar 26 03:14PM -0700 Tom Del Rosso wrote: ====================== > Why is it still necessary to worry about probing a floating ground? ** Errr - user safety ? > Most digital scopes have power requirements like high-end laptops, so > why can't they have a battery option? ** Battery scopes are potentially lethal. > They all have plastic cases, so why can't they have isolated supplies > and no earth connection? ** BNC plugs are metal and so are accessory connectors on the front and back. FYI My 1987 analogue scope ( 10x8 cm, 50MHz, dual trace) draws the same power as my 1052E ..... Phil |
| RosemontCrest <rosemontcrestwinery@post.com>: Mar 26 05:38PM -0700 On 3/26/2021 2:51 PM, Tom Del Rosso wrote: > why can't they have a battery option? > They all have plastic cases, so why can't they have isolated supplies > and no earth connection? I believe that Tektronix still offers the TPS2000 Series. |
| Phil Allison <pallison49@gmail.com>: Mar 26 07:43PM -0700 Phil Allison wrote: ====================== > FYI > My 1987 analogue scope ( 10x8 cm, 50MHz, dual trace) draws the same power as my 1052E ** Just rechecked, the Rigol uses 18W and the trusty BWD 825 only 15. It don't need a noisy fan either. .... Phil |
| Phil Allison <pallison49@gmail.com>: Mar 26 07:45PM -0700 RosemontCrest wrote: -------------------------------------- > > They all have plastic cases, so why can't they have isolated supplies > > and no earth connection? > I believe that Tektronix still offers the TPS2000 Series. ** Not the same idea and very exxe. Float the DUT - not the damn scope. .... Phil |
| Phil Allison <pallison49@gmail.com>: Mar 26 10:08PM -0700 Phil Allison wrote: ================ > > My 1987 analogue scope ( 10x8 cm, 50MHz, dual trace) draws the same power as my 1052E > ** Just rechecked, the Rigol uses 18W and the trusty BWD 825 only 15. ** Bugger - its a BWD 821 http://bee.mif.pg.gda.pl/ciasteczkowypotwor/B.W.D/bwd_821_001.pdf In 34 years of daily use, I have replaced 1 open 22kohm resistor and 1 pull switch mini pot. ..... Phil |
| "jurb...@gmail.com" <jurb6006@gmail.com>: Mar 26 10:31PM -0700 Well for one I think it voids most scope warranties. Now look, floating the DUT makes much more sense, there are very very few instances where you have to create that hazard, and anywhere civilized with regulations on this shit will require your area to be cordoned off so people cannot wander in. Grounds can be a very complex topic. Now one thing, if you find two 100WPC amps that are really fried out you can probably make an nice isolation transformer out of them. the voltage might not be perfect but god enough for testing. Some people may disagree here, but once you re out of the hot side you no longer need the isolation. for example I am working on a Crown and it has a SMPS power supply. I have to fix that. then Iher a something little wrong in it and now I am working on the cold side. now as long as you have your wits, and are not going to fsall and drown in a bowl of soup (Mary Hartski) you know where the hot side is, if not forget working on this shit. Where the cord goes ??? MAYBE ? I was working at a place, cement floor and on BIG TVs, many ties working on the floor. Well shit happened and I made them get an isolation transformer. "You get a isolation transformer in here NOW. WHY ? If you don't I am going down to the hospital after a shock and claim I can never work in my field again for fear and sue you for every fucking thing you got, BECAUSE YOU ARE SUPPOSED TO HAVE ONE !". Two days. Th only time you really have to float the scope, and there are, if you are in an industrial setting working on ike Fanuc or some type of NC or CNC, or on something in the plant like some thing that controls motors n shit. the need COULD arise. But you are not doing that. If you were you would not be here asking. In any unit you ever work on, of course if you have to work on the hot side get the transformer. And you make sure you know where the hot side is inside. Enough for now. just find transformers at least six amps with secondaries adding up to the line voltage. Cheapest and easiest way. |
| legg <legg@nospam.magma.ca>: Mar 27 08:51AM -0400 On Fri, 26 Mar 2021 17:51:59 -0400, "Tom Del Rosso" >why can't they have a battery option? >They all have plastic cases, so why can't they have isolated supplies >and no earth connection? There are scopes with battery power. I bought the Owon DS8202 for that reason, along with good memory depth. It's just one way of increasing measurement flexibility and of monitoring ground loop effects, but requires care in use. Even low voltage circuits can present energy hazards to technicians and their test equipment. For AC measurements, ground is everywhere, so your isolation should be limited to low frequency nodes. Can't say much for the scope - it has the usual triggering and noise issues as most of the present digital offerings. The battery can be expected to last ~3yrs. I refurbed the pack using cells from offshore and added a balancing circuit. Hopefully this will increase their lifetime. There are "handheld" scopes with internal batteries as well (Wave2). These can make low-frequency monitoring a bit less invasive and replace expensive differential probes, in some applications. Holding them in any energised circuit application is not advised. You need internal waveform memory to save data, if you want to process it on a grounded PC, later. RL RL |
| "Tom Del Rosso" <fizzbintuesday@that-google-mail-domain.com>: Mar 26 05:45PM -0400 Mike Coon wrote: > But then pigeon shit on the antenna might lead to discovering Cosmic > microwave background radiation > https://en.wikipedia.org/wiki/Cosmic_microwave_background ... That doesn't mention pigeons or birds. I vaguely remember there was a connection to the need to clean out the horns, but it would seem to be irrelevant since they would have detected the radiation anyway. -- Defund the Thought Police |
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