RIGOL DP832 neon blulb lights touched to output? - Page 1
Forum section: electronics / testgear

author: smile
author_rank: Regular Contributor
timestamp: November 17, 2021, 02:39:05 pm
content: Hello, just noticed that RIGOL DP832 neon blulb lights touched to output negative or positive, GND too.I tried reversing the plugI tried connecting without GND on the power plug.I thought it's transformer is insulated? Why do get cheap SMPS behavior here?Resistance meter measures O.L or Megaohms range on GND to negative pins, so what is going on?Furthermore this happens if output are OFF !@

author: smile
author_rank: Regular Contributor
timestamp: November 17, 2021, 03:12:21 pm
content: Seems like I need to remove the GND wire, remove the Y caps connecting GND and neutral.

author: knudch
author_rank: Regular Contributor
timestamp: November 17, 2021, 03:37:18 pm
content: That is the wrong way to go....You need to check your PE installation.I dont know which type Electrical network you are on (where in the world) ?If your PE installations is ok then it should not be a problem.Try to measure the AC voltage at GND ( enclosure parts) against phase and/ or neutral of the mains.Result should be 230 V(phase) or 0(neutral)Depending on the GRID network system

author: smile
author_rank: Regular Contributor
timestamp: November 17, 2021, 05:28:59 pm
content: No True PE is used.Electrical network is TNC-S, and I do not want to have Live wire potential on my system 50% of the time. (hot ground)Watch video about hot ground here:https://youtu.be/wHv33wndNTA?t=385

author: Gyro
author_rank: Super Contributor
timestamp: November 17, 2021, 06:34:26 pm
content: If you have the neon lighting on the output ground terminal, with or without the supply switched on then you have either a fault on your supply, your mains lead, or your house wiring. Does the neon light if you touch it to the PSU case? Do you have continuity between the output ground terminal and the case? Do you have continuity between the case / output ground terminal and the PE pin on the mains plug?Disconnecting the GND wire inside the PSU and/or removing the Y caps is definitelynotthe answer.On a TNC-S system, the house shared Neutral and PE connections are at (or very near) Earth ground potential as they are earthed at the utility transformer. If there is any suspicion that this is not happening, then you need to get your electrical installation checked urgently. Have you tried the PSU on another mains socket? It may be a defective PE connection on a single socket.Again, you should not be attempting to fix this by messing with the inside of the PSU, it needs proper methodical investigation.Quote from: smile on November 17, 2021, 05:28:59 pmThat's not how it works. PE remains at earth potential at all times, not 50% of the time.

author: smile
author_rank: Regular Contributor
timestamp: November 17, 2021, 06:49:34 pm
content: QuoteDid you see the video I linked?Yes PE is earth potential at all times if it's not connected to Neutral line at the house fuse box.QuoteAgreed, but tell this to Russia and all post sovied countries 90% has no dedicated PE ground, except private houses built after 2006 or so.And floating power supply like in medical field is normal not a hazard.

author: Gyro
author_rank: Super Contributor
timestamp: November 17, 2021, 06:59:32 pm
content: No I didn't, the video is 1 hour 23 minutes long(!) and appears to be about PC PSU repair.You said that your installation is TNC-S, is that not the case?I'm not sure what you mean by "dedicated PE ground". Do you mean an earth rod - if so, that only applies to TT and (very rare) IT systems. In a TNC-S, as I said, the PE comes from bonding to incomming Neutral, which is earthed by the supplier at their utility transformer (It is not "hot ground").It would be helpful if you set your country flag, so that people with more local knowledge of the mains supply conditions can comment.P.S. Maybe you can post a photo of your incoming mains supply installation.

author: electr_peter
author_rank: Unknown
timestamp: November 17, 2021, 08:39:52 pm
content: Likely you do not have proper ground connected at all in your wiring. Ground in mains socket could float somewhere between neutral and line. This in term would make local grounds float at half mains voltage (although at high impedance). Not the best situation (or very bad situation if something goes wrong).Do you have multimeter? Can you check AC voltage between line/earth and neutral/earth in a socket? If both readings show ~half mains voltage, there is no ground. Disconnecting false ground in PSU is not recommended and would not help much if at all.

author: knudch
author_rank: Regular Contributor
timestamp: November 17, 2021, 08:45:47 pm
content: If installation practice and quality is so poor.I would buy a isolation transformer for the LAB and make a local PE system connected to the core of the transformer.Anything else would be a gamble with your life.All equipment made of metal housing would be dangerous (normal protected by PE system)

author: smile
author_rank: Regular Contributor
timestamp: November 17, 2021, 10:26:48 pm
content: for SMPS here is my findingshttps://i.postimg.cc/SNHpbnX9/safe-psu.pngliteon_pa-1121_04Works fine over here where DP832 does not, meaning neon bulb does not blow with this Liteon.No Y caps to ground.https://i.postimg.cc/g0H9h4gy/unsafe-psu.jpgAll others with Y caps.Notice the difference

author: Gyro
author_rank: Super Contributor
timestamp: November 17, 2021, 10:35:49 pm
content: I don't understand where you're going with this. Why aren't you answering the questions that people are asking in order to try and help you, rather than posting random stuff?You show two schematics, one has Y caps, the other doesn't. So what? It's irrelevant if you have a working PE. We're trying to understand if you do or not (have an electrical safety issue). If it's TNC-S then you should have a working PE (ground).

author: commongrounder
author_rank: Frequent Contributor
timestamp: November 17, 2021, 11:00:20 pm
content: Yes! This!I’m reading this thread in horror.If you are planning to set up a reliable, safe electronics bench, you MUST have a solid, low impedance physical ground/earth at the AC supply to your shop. If your AC receptacles have three contacts, you need to have an electrician come and check the wiring in the building to uncover why there is no grounding/earthing established on equipment plugged in to those receptacles. We cannot urge you more strongly to seek professional help with this issue.

author: smile
author_rank: Regular Contributor
timestamp: November 17, 2021, 11:33:10 pm
content: It's amazing that instead of wondering why toroid transformer linear LAB PSU for 500EUR has Y caps you want me to change building wiring for 120 flats? Crazzzy.I gave you links that even SMPS can be built safe.

author: james_s
author_rank: Super Contributor
timestamp: November 17, 2021, 11:37:18 pm
content: If you think it's amazing that people are concerned about the integrity of the protective earth wiring and suggesting you check that instead of trying to modify your equipment to work around a fault then perhaps EE is not for you. There's a saying for what you're wanting to do, "the tail wagging the dog".

author: Gyro
author_rank: Super Contributor
timestamp: November 18, 2021, 10:25:00 am
content: Quote from: smile on November 17, 2021, 11:33:10 pmBoth the PSUs you show are probably safe (I can't tell generally from so little information) but the presence of Y caps is perfectly normal, they have a very high breakdown rating, don't pass enough current to pose any sort of shock hazard and are agency approved.This has nothing to do with your Rigol situation however. Yes it has Y caps, but they return their current directly to the PE (ground pin on the mains plug), it should not appear on the output ground of this linear PSU. The only reason you can light a neon from the output ground pin (and case? - that wasoneof the questions you didn't answer, is because there is a fault in the PE (ground) circuit. As I havealreadyexplained, this is either a fault in the PSU, the mains lead, your wall socket, your flat wiring, or the entire building. It would be sensible to find out which!Please stop getting hung up on Y Caps, they are NOT the problem.Best case you have a dodgy mains lead or wall socket - worst case, if anyone in the other 119 flats has a faulty appliance, some of you get electrocuted. A sensible person would concentrate and follow the simple fault finding checks / questions that have been posted previously.If you are going to jump to silly conclusions without following sensible advise then please stop wasting other peoples time. "Crazzzy" enough?