Jump to content
Sign in to follow this  
Kimmo

Anyone know much about power conditioners?

Recommended Posts

I think that's what I mean, but I could be wrong - the issue I'm having is a cheap telly that often drops out for a few seconds if someone turns on a kettle or something...

 

All I really need is a UPS that only needs to do its thing for a second or two. Is that a thing?

Share this post


Link to post
Share on other sites

Supposedly they provide a clean AC sine-wave and compensate for any voltage dips or spikes.

 

A UPS will generally do the same - my one occasionally reports a voltage drop though it's usually during a storm and feels like a short brownout (lights dip, sometimes other appliance turns off).

 

Some UPS's (I think including mine) only output an approximated sine wave which can be a problem with some things, though it's usually AC motors which depend on a smooth waveform - I actually tried a low wattage variable speed dremel clone from memory and it wasn't too bad though I didn't test it under load.

 

For the most part, computers and TVs don't give a crap anyway since they mainly convert it to lower voltage DC and often if there's an AC requirement it's derived from that DC anyway.

 

One thing I guess I could try - I've got an oscilloscope and some simple low voltage AC transformers so I could probably check the waveform out.

Share this post


Link to post
Share on other sites

Yeah, I'm pretty sure the fancy business of tweaking the waveform just so is totally redundant - I just need like a UPS with a AA battery instead of the usual lump. 

 

Been googling for something basic like that (say, $35 worth), but I'm drawing a blank... Either what I'm after isn't a thing, or I lack the right search term.

Share this post


Link to post
Share on other sites
On 6/21/2019 at 9:36 PM, Kimmo said:

I think that's what I mean, but I could be wrong - the issue I'm having is a cheap telly that often drops out for a few seconds if someone turns on a kettle or something...

 

i assume the kettle or something are on the same circuit.  maybe you could run an extension to another circuit and see if symptoms persist.  probably not a permanent solution, but i know i would want to know! 

 

is it an LCD TV?  maybe you could replace the power supply yourself? 

Share this post


Link to post
Share on other sites

The other thing - is it a signal dropout or the TV actually powering down then up - it can be fairly common for an electrical spike to make modern TVs just drop the signal for a little bit.

Share this post


Link to post
Share on other sites
Posted (edited)

When you say 'drops out' is it

1. The TV controller freak out/crash (conducted/mains noise)

2. The tuner that stops receiving signal  (likely TV RF interference, although it could be getting in through the mains)

3. The TV powers off then on (brownout) - if so the wiring/switchboard in your house might be under specification if a local appliance is causing this.

 

Mains Power conditioner can be an interesting term. There are levels of conditioning. Many are just analogue filter circuits that clean  up the mains to remove induced/conducted noise from switching, motors or data appliances - let the 50Hz through, but stop the higher frequency junk and cost from a few dollars to a few hundred dollars and price should reflect performance (although your need may not justify top performance). A double conversion conditioner (not cheap options) will also correct voltage and frequency variations.

This is all separate from surge/lightning protection filters which get rid of dangerous spikes - and of course many power conditioners include those, as they start with a $1 part but surge protection bits are usually self sacrificing, while filtering is continuous and non destructive.

None of those conditioner devices address a brown-out where there is loss of power.

 

If it is RF interference, then you will need a filter between the antenna  and the TV to try and block the interference.

Switching noise will be tough, but might be improved by a bandpass filter that reduces the noise outside the TV bands and in theory should improves performance within that band - but results may vary. A mats-head amp may also help if you are in a weak TV signal area, and by the time the signal from the antenna gets to the TV is is close to the noise floor - having a stronger TV signal will improve the TV's ability to decode it)

If it was a specific and persistent interference from an appliance you would get a notch filter to take out that specific signal - but it doesn't sound like that.

 

A UPS will address brownouts of course, and many UPSs include some power conditioning capability as part of their design, and they can be applied in a number of ways

- to condition the noisy mains

- to clean up the inverter waveform when running (either continuously in a double conversion, or for line-interactive part)

Edited by stadl
  • Yes Sir! Very atomic! 2

Share this post


Link to post
Share on other sites

I wonder... would something like this help?  But that's assuming it's spikes causing the issue.

 

 

 

Share this post


Link to post
Share on other sites
Posted (edited)

Sorry, I wasn't clear - I use the telly mostly as a monitor, so it's not the crappy tuner (other tellies pull in channels just fine that this one can't even see, so it's plugged into a STB for when I want to do free to air).

 

And it's not the fault of the house wiring; I'm in a new house and it's the same (or maybe worse), and if I put another telly in its place there's no problem. It's a Dick Smith POS, 41.5" UHD I got for $400.

 

So given the issue coincides with the onset of pretty much any other power draw, and that the tuner is rubbish, and that this problem has existed from day one, it seems like the power supply is inherently a piece of shit, and replacing it will do no good.

 

It also seems my needs could be met by something containing little more than some of the components you'd find in a decent power supply...?

Edited by Kimmo

Share this post


Link to post
Share on other sites
22 hours ago, Kimmo said:

And it's not the fault of the house wiring; I'm in a new house and it's the same (or maybe worse), and if I put another telly in its place there's no problem.

 

yeah, but what happens if its on another circuit?  😄

 

22 hours ago, Kimmo said:

...it seems like the power supply is inherently a piece of shit, and replacing it will do no good.

 

wouldnt you be replacing the thing that is shit?

Share this post


Link to post
Share on other sites
1 hour ago, @~thehung said:

wouldnt you be replacing the thing that is shit?

 

I'm tipping that it's under-specced junk, like the tuner. This is Dick Smith we're talking...

Share this post


Link to post
Share on other sites
9 minutes ago, Kimmo said:

 

I'm tipping that it's under-specced junk, like the tuner. This is Dick Smith we're talking...

 

yeah, so maybe you can open it up, and see if you can buy something with a little more grunt that will fit in its place ... or solder in larger cap or something like that...

 

why so silence re the circuit?  you may have an outlet in an adjacent room that is on a different 10A circuit.  its potentially a quick test, if this problem is predictably repeatable.

 

also, probably won't make any difference at all, but is there any setting on the TV that might lower the power draw, for example lowering the back light?

Share this post


Link to post
Share on other sites

The DS branded stuff is just generic Yumcha with added sticker engineering.  So probably the same guts as a Conia, Tivo, Philsonic, Tevion, or other cheap junk.

 

Backlight I do suspect would be trivial if it's an LED one.

 

What's needed is pull the power board then get some decent pics and give Big Clive a yell.

Share this post


Link to post
Share on other sites

UPS even now essentially come in two flavors, always on or short break.

 

With always on you are essentially always running off  battery that is trickle charging in the background - those are not cheap.

 

Short break works by detecting a sag on the rail and switching you over to battery. They can be very cheap but most of the time the reaction is far from instantaneous and if you are only seeing short interruptions I rather doubt that anything cheap would react in time.

 

Sorry to say YMMV but you could spend a deal of time and effort and returns and get no reliable outcome.

 

In the end I'd say cheaper to either accept it, annoying as it is, or bite the bullet and get a better monitor, with a decent return policy.

 

@th's suggestion is not a bad, and cheap, option though, worst case an extension cord, so long as there is another circuit in the house that is not loaded by other interrupting equipment   🙂

 

Cheers

 

 

 

 

Share this post


Link to post
Share on other sites

I found the cheap Jaycar (Digitech?) one handled power cuts not very well.  My CyberPower which is overrated (VA) for what I use hasn't had any problem handling dips and brownouts that used to cause reboots.

Though that said I no longer use the Dell workstation that was the reason for getting a UPS in the first place - it never seemed to handle power dips very well and would restart in situations you'd expect any other desktop to be fine.

 

I do suspect though that a decent modern PWM type power supply be it computer or TV, should handle voltage dips just fine anyway since many of them are universal and handle any input from ~ 100 to 250V.

Share this post


Link to post
Share on other sites
3 hours ago, Rybags said:

 

I do suspect though that a decent modern PWM type power supply be it computer or TV, should handle voltage dips just fine anyway since many of them are universal and handle any input from ~ 100 to 250V.

 

It's an interesting thought on the power systems these days.

A brown-out/power sag, is usually observed as an under-voltage event - either a straight voltage drop caused by power factor issues, or generator variances or a temporary capacity drop due to overload. If you exceed the capacity of a power source, the terminal voltage starts dropping.

 

In days gone bye, many appliances were voltage sensitive, so when the circuit got overloaded, and supply voltage started dropping, some of the appliances would  switch off, and thus you effectively have some load shedding that then addresses the overload 🙂

Modern switch mode variable frequency and voltage PSUs will happily continue to generate load. As the voltage goes down, they just draw more current to keep the same power drain (watts) - so no serendipitous load shedding happens.

 

Probably not that common on the mains, but certainly very easy to have happen with battery systems. e.g. a DC-DC converter plugged in to a car battery may happily suck the 12V battery to 3V or lower while delivering the output voltage to the device if it doesn't have low voltage cut-out on the input that would prevent the rechargeable battery being depleted to to the point it can't be recharged.

  • Yes Sir! Very atomic! 1

Share this post


Link to post
Share on other sites

For whatever reason, probably at least in the CFL backlight days, LCD TVs and monitors often seem to use a transformer type power supply.  I would think probably due to wanting to retain AC for the backlight rather than having to regenerate AC?

But for modern LED lighted ones I can't think of why you'd need AC anywhere inside the thing?  Maybe it's just down to being cheaper or just that there's some huge surplus of transformer windings that the suppliers want to get rid of.

Share this post


Link to post
Share on other sites

This POS is definitely LED, but only has a brightness control, nothing for the backlight. Very basic menu.

 

I probably should get off my arse and suss out which circuit is which... there are six, and the labels are half illegible. But it's weird - this problem I'm having definitely coincides with the onset of power draw from something or other, but it's not consistent, which has I guess discouraged me from bothering to check if it's repeatable - I'm thinking it probably depends on how my power is coming down the line at time too.

 

On 7/4/2019 at 2:09 PM, stadl said:

Modern switch mode variable frequency and voltage PSUs will happily continue to generate load. As the voltage goes down, they just draw more current to keep the same power drain (watts) - so no serendipitous load shedding happens.

 

So you're saying I shouldn't be having this problem because the power supply is switch mode? Sounds legit. But is it conceivable the spec is so stingy it can't fill the brief?

 

Could I maybe chuck bigger caps in it as @~ suggests to fix it?

Share this post


Link to post
Share on other sites
23 hours ago, Kimmo said:

So you're saying I shouldn't be having this problem because the power supply is switch mode? Sounds legit. But is it conceivable the spec is so stingy it can't fill the brief?

 

Could I maybe chuck bigger caps in it as @~ suggests to fix it?

 

They should cope if it was a small brownout. If it is switching noise then it may still crack the shits because the cheap PSU would not regulate well and the switching noise gets through onto the digital circuit boards that are expecting nice constant DC.

 

I would strongly discourage changing capacitors in switching PSUs unless you know what you are doing.

 

The old upgrade the caps fix is fine in linear power supplies where the capacitors are used to smooth the power.  In that case it only holds the voltage through the fully rectified sinewave. Most of the time, the larger cap just means instead of going from 100% down to say 30% each cycle, it goes from 100% to 60% so it has more reserve capacity, and also because of the drop-off rate, the output voltage ripple is much lower. Under that upgrade, the capacitor change doesn't materially change the circuit design, other than slightly increasing the surge current into the capacitor (through the transformer and rectifier) for the first half sine-wave after power is applied.

 

Switching power supplies are more complex, and their frequency, stability and efficiency can all be linked to the capacitance and inductance of parts of the circuit.

Upset the efficiency and it may not operate within the thermal specification and could overheat leading to a bad day.

In many designs it might be safe to upgrade the final stage smoothing capacitors. but other capacitors that are part of the switchmode circuit, much less safe - what design is it, and what is safe - hard to tell, so I'd be for not changing them.

 

If it is an external PSU brick, then you could build a smoothing capacity circuit (electrolytic in parallel across the connection from the PSU to the device), but if it has an external PSU, you are probably better just trying to find a replacement from another device for testing - unless it is some odd-ball voltage or connector.

 

DANGER WARNING 

 ******** 240V construction!!!  Do not consider unless you know about safe construction of 240V wiring  ********

If it was me, I would consider building a budget 240V mains EMI filter to put between the cheap device and the power point and hope that cleans up the power enought for the shitty PSU

Whack one of these in a a box with a GPO outlet or IEC Female panel mount, and you have an in-line filter.

https://www.jaycar.com.au/240v-ac-emi-filter/p/MS4001 or https://www.jaycar.com.au/iec-emi-power-line-filter-6-amp/p/MS4003

I have a similar one for my HT system, but the filter I bought cost about $80.

Disclosure: EMI filters exhibit a small amount of earth leakage by design - if you use too many of them , or a very sketchy safety switch, they can trip it - but these small ones are fine.

  • Yes Sir! Very atomic! 1

Share this post


Link to post
Share on other sites
20 hours ago, stadl said:

Whack one of these in a a box with a GPO outlet or IEC Female panel mount, and you have an in-line filter.

https://www.jaycar.com.au/240v-ac-emi-filter/p/MS4001 or https://www.jaycar.com.au/iec-emi-power-line-filter-6-amp/p/MS4003

I have a similar one for my HT system, but the filter I bought cost about $80.

Disclosure: EMI filters exhibit a small amount of earth leakage by design - if you use too many of them , or a very sketchy safety switch, they can trip it - but these small ones are fine.

 

if the TV has one of those three-pronged female power inputs, is there any reason to think it might already have this kind of filtering?

if the TV is at least earthed, do you foresee any problems lifting it via the chassis mounted option above?

could the 6A rating on the IEC thingo be an issue?

Share this post


Link to post
Share on other sites

Hmm, thanks for the lesson @stadl!

 

I like the look of this...

 

MS4003-iec-emi-power-line-filter-6-ampIm

 

This shitbox thing isn't earthed - what if I earthed the chassis using this nifty jigger? Trip the circuit breaker straight away, or would it be a safety improvement? Is there a chance that might even help my problem?

 

@~, the telly is only 80W, which is just 1/3A, right?

Share this post


Link to post
Share on other sites
2 hours ago, Kimmo said:

@~, the telly is only 80W, which is just 1/3A, right?

 

internally, its probably using much lower DC voltages at much higher currents. 

 

at 80W, it could draw over 6A at 12V, for instance, although i suppose its probable that under any normal condition it would never come close to that ???  its probably transformerless power supply with a fuse that will tell you the safe maximum.

 

Share this post


Link to post
Share on other sites

It's unlikely it would have something like that in it.

Budget devices are not known for having much filtering, and if they do, it is more likely a couple of extra components on the PCB rather than an off the shelf module like that.

 

At 6A, it's good for about 1300W (at Australian Voltage) - more than enough for a TV and even a few home theatre devices  except maybe a honking great A or AB class surround amplifier - and if you have one of those  you probably aren't using a budget DSE TV :)

 

If the device is double insulated (no earthed chassis) then best not to change the earth design. If it is using a figure-8 power lead, or a power lead without an earth pin, then forget using one of those filters, as they work by filtering common mode (line to ground) noise. If you have no ground on the power to the device, then there is no way for a line-ground noise signal to be the issue that this can fix.

But if the device has a earth pin, and it's connected to some part of the PSU electronics - it may help, but no guarantees.

  • Like 1

Share this post


Link to post
Share on other sites
1 hour ago, stadl said:

If it is using a figure-8 power lead, or a power lead without an earth pin, then forget using one of those filters, as they work by filtering common mode (line to ground) noise. If you have no ground on the power to the device, then there is no way for a line-ground noise signal to be the issue that this can fix.

 

thats what confused me about the chassis mounted option.  it seems to have an input and output side — and the line side only has two pins.  is it assumed the ground from both mains and TV would be soldered to the load side?

Share this post


Link to post
Share on other sites
On 7/9/2019 at 11:21 PM, @~thehung said:

 

thats what confused me about the chassis mounted option.  it seems to have an input and output side — and the line side only has two pins.  is it assumed the ground from both mains and TV would be soldered to the load side?

 

Yes, the earth/ground is common to both the input and output of the filter.

 

Remember at this stage, it's all still AC, so you have active, neutral and earth.

After going through the filter, you still have active, neutral and earth, with 230V AC RMS between active and neutral - neither is connected to earth.

But the filter will reduce noise between active<->earth and noise across neutral<->earth

 

What this means, is that if you have an appliance that is never never connected to the mains wiring earth, these filters won't help as much - there is a small amount of filtering across active<->neutral.

 

An earthed appliance does not just mean an appliance with a metal case connected to earth. The protective earth may be present in an internal chassis or PCB - so long as an earth is present, these filters will offer their designed protection.

But the give away is that if there is no earth cable on the mains lead (it's a 2 pin/2 wire lead) then there must be no protective earth used in the circuit - which is quite safe for a double insulated device - and in that case, introducing an earth to the device would be dangerous.

But using a earthed filter and not connecting the earth would be ok.

 

Reminder, this is still working with dangerous voltages, and if you are not sure of what you are doing and your assembly skills, don't try this.

  • Yes Sir! Very atomic! 1

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this  

×