Vacuum tube (Valve) Amplifier Hum - opinions please

[bankruatsteve]

19 minutes ago, Wirejerker said:

Please don't follow this info as it is corrupt. The forum has told you what the problem is now get a electrician to fix it.

 

Not a good start there newbie.  First, you can take "corrupt" and put it back in your bag of big words as it's not applicable here.  The poster just wanted to find out if the ground wire in his outlets actually connect to ground.  Even if a Thai electrician had the expensive earth ground loop tester it really isn't required for this purpose.  So, if that was going to be your recommendation, you need to remember TIT.

[Wirejerker]

3 hours ago, bankruatsteve said:

Not a good start there newbie.  First, you can take "corrupt" and put it back in your bag of big words

Sorry about the  word but it's use was correct. I have read your posts and can see you know your stuff so read this again and check that multimeter reading

 

On 24/12/2016 at 7:45 PM, bankruatsteve said:

take a reading from ground in the outlet to the wire connected to the ground stake.  If it just sits at 0 and doesn't blink, then you have no continuity to ground

0 ohms indicates excellent continuity

Now we have a layman with an earth wire, and a DMM in front of a power point that we hope he isolated the right circuit and the polarity is correct.. Who put him there

It is a lethal setup. Lift your bar semi concerned and don't use TIT as an excuse

[Crossy]

Ok gentlemen, let's play nicely.

 

We should add to our advice to open the main breaker before poking a DMM into an outlet when on Ohms (although it's not unknown for even that to leave things live). Even a neon screwdriver will at least suggest that things are dead (but it should be verified working before use).

 

How your DMM indicates open-circuit will vary, I would be wary of an indication of zero, it rarely happens.

 

I can only assume Wirejerker hasn't tried to find a decent domestic sparks in Thailand (who knows what the ground wire actually does). They do exist, but are mostly engaged on the mega-projects or O&G leaving the dregs for us mortals.

 

Our problem with this forum is we really don't know just how competent our members really are, short of vetting everyone we have to make some assumptions. It's often possible to decide the level of advice to give by reading the member's posts varying from "call an electrician" (good luck finding one) to detailed instructions on how to locate the N-E fault that's causing your RCD to trip randomly. The alternative is of course, to not give any advice, would anyone recommend that in Thailand?

 

[Wirejerker]

You just flashed your TIT card

[Crossy]

26 minutes ago, Wirejerker said:

You just flashed your TIT card

 

Do you have an alternative solution? Have you ever actually been to Thailand?

 

Things are rather different here to what they are in Oz.

 

[asianscouser]

Been reading through these comments. 1. Not sure if you're looking for a power supply? Have you thought about solar power? (Assuming I read correctly). 2. I've been looking for fellow musicians. I play guitar, influences, Beatles, Pink Floyd, dire straits, Sex Pistols ETC.


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[bankruatsteve]

To clarify the use of a DMM for checking continuity...  As I said in my post on the subject, turn off power when measurements are required from the "ohms" scale.  All DMM's that I have used will show "0" on an open circuit (IE: no connection).  When there is continuity and the ohm value is zero, the DMM will blink, show a "-" sign and or beep to indicate a reading of zero versus a reading of nothing.  

[asianscouser]

Mmmm...........
 
OK, you are now talking Greek to me.
 
I don't understand that level of electric tech.
 
It would be great of I could get a sparky that I can trust to do the job right..............but I'm not sure I can. That's the whole point of my posting here.
 

• Firstly, I want to get the ground in my house sorted out, so that the devices attached to it will not hum.
   
• The ground-loop is a red herring, I think, because it's an effect that happens when different devices are connected to each other in a loop, which causes hum. My hum is caused directly from connecting to an un-grounded mains supply.

What I'd like to know is how to test  whether all my 3-wire plugs are really providing a ground, because I don't think they are.
 

My friend did mine. In fact I'm sure he had to fit a 6 foot ground rod, he did all the copper fittings and everything, let me know if you'd like me to have him contact you.


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[Tapster]

@asianscouser

 

We are fellow scousers! 

 

It would be great if your friend could check this out for me. Where are you based, though? I'm in Phuket. 

 

[asianscouser]

Pattaya mate.


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[Tapster]

Bugger! 

 

Thanks for the offer, though. 

[Crossy]

I just checked my cheapo DMM (the Fluke is in the office).

 

On open circuit it displays a "1"  in the leftmost (most significant) digit.

On short it displays 01.2 (on the 200 Ohm range).

 

I've never met a DMM that displays a "0" anywhere on open circuit (that does not mean they don't exist), "- - - -" is quite common.

[RichCor]

44 minutes ago, Crossy said:

I just checked my cheapo DMM (the Fluke is in the office).

 

On open circuit it displays a "1"  in the leftmost (most significant) digit.

On short it displays 01.2 (on the 200 Ohm range).

 

I've never met a DMM that displays a "0" anywhere on open circuit (that does not mean they don't exist), "- - - -" is quite common.

 

Not that I want to get into the middle of a cat fight...

 

but I think if I ever suggested someone use a DMM to check effectiveness of their grounding system I would have them power off the circuit, use a simple plug-in light to verify it was previously on but not off, then first measure for VOLTAGE across L/N, N/G and G and a long wire to a temporary ground stake. If every thing measured close enough to zero to be called zero, then and only then would I suggest continuity or measuring Ohm values.

 

Crossy and Forkinhades have already contributed to several great electrical threads, one of them being:

 

How to check your earthing system
Started by Forkinhades, January 5, 2014

 

...though all of these suggestions usually presume the poster wanting some advice and direction has *some* hands-on electrical experience and appreciation for safety requirements when working around electrical wiring.  

 

Given the OP's posts, I wouldn't suggest they go anywhere near a power point while holding a butter knife, let alone a set of DMM probes.

Edited January 3, 2017 by RichCor
add link to post

[RichCor]

Tapster,

 

Have you asked around your local haunts for a good electrician yet?

 

Just wondering how you're getting along  ...and if you've taken your Guitar, Effects Peddle and Amp to another building and not had the hum issues (meaning the issue in your house, not the sound system).

[bankruatsteve]

1 hour ago, Crossy said:

I just checked my cheapo DMM (the Fluke is in the office).

 

On open circuit it displays a "1"  in the leftmost (most significant) digit.

On short it displays 01.2 (on the 200 Ohm range).

 

I've never met a DMM that displays a "0" anywhere on open circuit (that does not mean they don't exist), "- - - -" is quite common.

 

Just to expand the research... I have two somewhat expensive ammeters with DMM - both of those show "0.L" when set to ohms and the leads just hanging.  Both of those have option to set to beep for continuity which is what I usually use for checking that.  My cheap Tesco DMM just shows "0" when set to ohms and the leads hanging but will do the blinking dance with continutity.  There you go.

[Wirejerker]

48 minutes ago, Crossy said:

(the Fluke is in the office

To save u a trip to the office it will read "OL" which means Open Loop. All DMM will read OL or 1 when put on the ohms scale with an open circuit. Never 0 and only will give a reading of nothing when switched off. I know u fellas know your stuff and most likely more than competent using a multimeter but u must be accurate when your describing the procedure to a layman putting them in the line of fire. Would u give your wife a multimeter an earth stake, a trailing lead and the info given previous then nick out for a beer. Maybe.. I'm sorry I only jumped in when I could see all the cherries lining up for tapster and I pleased to see he made it through Xmas.

I have been following this forum out o curiosity as I have visited Thailand for 8 weeks in the last 18 months. Yes u r right I know nothing John snow I even had to look up the meaning of TIT

[bankruatsteve]

I think we can all agree that no matter what DMM you have, when set to ohms with the leads just hanging, it will display something and when the leads are connected to a circuit that happens to have a measurement of zero ohms, the display will show something different.  Yah?

[Wirejerker]

I'm beaten. Who can argue with a telco meter. It's not all bad I learnt what a TIT is

cheers. 

[Tapster]

 

Momentarily returning to the topic, 

 

@RichCor

 

You have given me some useful advice, especially the part about not taking a butter knife to my consumer unit. Thanks for that gem.

 

I'm going to make a power cable with a ground lead which can be staked in the ground/fixed to a known ground, so that all my sound equipment will run off that. Problem solved.

 

Then I'm going to get my butterknife and check my household supply, using that useful Forkinhades post you linked to, and other well-researched references from the Internet.

 

 

 

Thank you all for your help on this one!!     

[Forkinhades]

Just casually browsing this. :)

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[Tapster]

@Forkinhades

 

I've now read your thread on earth systems in Thai houses and Crossy's website is helpful as well. I'm going to check out the earthing system in my domestic supply.

 

Regarding the guitar amp, I've just arrived back from Rawai Hardware (Phuket) with cable and pugs and sockets to make a Franken-socket.................a two-pin mains power strip with a separate 15 metre ground cable coming off it which can be routed outside the house (wherever I am) and attached to a ground spike, so that there will be no hum or ground loops in my new amp-guitar set up........and also I won't get electrocuted!! 

 

After that, I'm going to be OK soundwise but I've also bought several three-pin plugs to put on the various white goods which have three-core cable but only two-pin plugs. I also bought a couple of power strips with a three-pin plug, and better quality than the usual crap. I'll take the power strips apart to make sure that the earth on the three-pin plug is connected to an earth inside the socket....you never know!

Many thanks for your helpful articles.

 

 

[Forkinhades]

Indeed you never know!
Many 3 pin power strips sold here that don't have an earth wire!

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[Tapster]

 

Yay!

 

The sockets are correctly earthed....and only 220 THB for a 4-socket strip with a fuse, an LED and a master power switch....and sockets that take everything, even a UK plug!

 

Bargain!