earth the chassis when draining filter caps?

Valentine Smith · 10-16-2009, 10:33 AM

Hi,

Later on I'm going to clean my switches and tube sockets on my SL-X 2500 and like a good boy first I'm going to drain the filter caps with my newly made 2 croc clips with a resistor in the middle device by clipping one end to the chassis and then touching the other clip to the caps contacts for a few seconds. (one hand behind the back)

But my question is I'm going to do this on my wooden kitchen table so do I also have to have the chassis connected to a good ground point at the same time or is good enough to drain to the chassis just sitting isolated on the kitchen table?

jcmjmp · 10-16-2009, 10:46 AM

No need to ground the chassis. The energy is dissipated through the resistor.

PaoloJM · 10-16-2009, 10:51 AM

Quote:

Originally Posted by Valentine Smith

Hi,

Later on I'm going to clean my switches and tube sockets on my SL-X 2500 and like a good boy first I'm going to drain the filter caps with my newly made 2 croc clips with a resistor in the middle device by clipping one end to the chassis and then touching the other clip to the caps contacts for a few seconds. (one hand behind the back)

But my question is I'm going to do this on my wooden kitchen table so do I also have to have the chassis connected to a good ground point at the same time or is good enough to drain to the chassis just sitting isolated on the kitchen table?

The purpose of draining the caps is to neutralise the charge difference between the + of the cap and - which is almost always also the chassis potential.
You don't require an actual earth reference for this.

Wilder Amplification · 10-16-2009, 11:16 AM

On most amps, the trick I use is to use an alligator jumper between pin 1 of the first preamp valve and the chassis. This will basically use all of the power supply resistors as well as the plate resistor for one side of the preamp valve as "bleeder resistors" as the current will have to go through the resistors themselves to get to ground.

Notes on ground -

All "ground" is is a "reference point". It's just a way to reference one side of the circuit so that any and all voltage measurements are taken relative to this reference. It can be positive or negative, although most circuits use a negative ground reference. The bias supply is a perfect example of a circuit which uses a positive ground reference, which is why it has a negative voltage relative to ground. A short to ground is a short which exists between the side of the circuit opposite the grounded side and the grounded side. All filter caps have 1 terminal referenced to this ground reference, so by using a resistor to connect the positive side to this reference, it ends up placing a resistive short across the capacitor since one side of the capacitor has a direct connection to this reference.

And yes...current flows through this reference. However, the reference has 0 volts because the reference has no resistance. The voltage difference exists between ground and the positive side of the supply because there is a positive charge on the opposite side of the circuit and the current that flows from ground, through the circuit, which has a resistance to current flow. The resistance of the circuit itself allows this voltage to exist, just like resistance to water flow creates pressure. If you were to short the power supply to ground, voltage would seize to exist since current would be able to free flow from one side of the supply to the other and you would no longer have a difference in the amount of electrons between negative ground and the positive side and an equal amount of electrons would exist on both sides of the supply. It's the difference in the amount of electrons on each side of the supply (the negative having a surplus of electrons while the positive has a shortage of electrons as compared to the negative side) that creates the charge difference, which is expressed as a voltage. The resistance to current flow allows this difference in electron count to exist between ground and the positive side of the supply. If a circuit of zero resistance (i.e. a wire placed between ground and the positive side of the supply), all of the electrons from the negative side would be allowed to flow to the positive side, equalizing the number of electrons on both sides of the supply, which removes the voltage/charge difference between both sides of the supply.

Frankie · 10-16-2009, 11:39 AM

I always ground mine. I don't know about you, but I don't wanna chance a bum resistor and find out I have a 500 volt chassis when I touch it. Is it really that hard to plug the thing in?

Wilder Amplification · 10-16-2009, 12:13 PM

Quote:

Originally Posted by Frankie

I always ground mine. I don't know about you, but I don't wanna chance a bum resistor and find out I have a 500 volt chassis when I touch it. Is it really that hard to plug the thing in?

Can you explain to me just exactly how you would ever have 500 volts on the chassis?

Also, much safer to do it with the amp unplugged so that you're not exposed to wall/mains voltage.

And if you really want to get down to it, most amps utilizing bleeder resistors on the first two filtering stages bleed the charge off automatically within 30 seconds due to having resistors across each filter cap to ground.

Frankie · 10-16-2009, 12:36 PM

Quote:

Originally Posted by Wilder Amplification

Can you explain to me just exactly how you would ever have 500 volts on the chassis?

Also, much safer to do it with the amp unplugged so that you're not exposed to wall/mains voltage.

Maybe I'm missing something here, but if you clip the positive lead of a cap can to the chassis and that voltage has nowhere to go, doesn't that make the chassis the positive lead of the cap can which is holding 500vdc?

andyman95023 · 10-16-2009, 12:37 PM

Just curious if something like a light bulb would work in place of the resistor for a visual indication of draining

Thanks
Andy

Frankie · 10-16-2009, 12:37 PM

Quote:

Originally Posted by andyman95023

Just curious if something like a light bulb would work in place of the resistor for a visual indication of draining

Thanks
Andy

I always like to use a volt meter. Little more accurate than a light bulb.

Wilder Amplification · 10-16-2009, 12:48 PM

Quote:

Originally Posted by Frankie

Maybe I'm missing something here, but if you clip the positive lead of a cap can to the chassis and that voltage has nowhere to go, doesn't that make the chassis the positive lead of the cap can which is holding 500vdc?

No because the negative lead is also connected there, eliminating the voltage difference between the positive and negative terminals because an equal number of electrons now exists on both sides of the cap due to them being connected together through the chassis.

A capacitor is nothing more than two pieces of metal that are in close proximity to each other, but are physically seperated from each other. On a charged capacitor, one of the pieces of metal has an excess of electrons (negatively charged side) while the other has a shortage of electrons (positively charged side). The negative piece of metal is connected to the chassis, while the positive piece of metal is connected to the positive side of the supply. As soon as you connect the pieces of metal together, electrons flow from the negative side (the grounded side) to the positive side, thereby equalizing the electron count on both pieces of metal, which neutralizes the charge on the capacitor. When using a resistor across the caps instead, it does the same thing, just takes it a tad longer to bleed the charge off the caps. It's better to do it this way to keep from "shocking" the cap by discharging it too quickly.

If the resistor you were using to discharge the caps were a bad resistor, no current would flow, hence the charge on the capacitor would never be bled off. This will pose a shock hazard whether you have the chassis grounded or not, because a charge will still exist on the capacitor.

Valentine Smith · 10-16-2009, 02:04 PM

Thanks very much for the advice.

And I also learnt some useful theory, thanks for taking the time to explain that Wilder Amps.

I've bleed the caps and cleaned the switches and it was all very uneventfull. I'm just waiting for it to all evaporate (the cleaner not my amp) before I put it all back together and plug in.

I did find some strange black stuff on one of my PCB's but I'm going to post it in the amps forum with a pic.

Wilder Amplification · 10-16-2009, 02:11 PM

Quote:

Originally Posted by Valentine Smith

Thanks very much for the advice.

And I also learnt some useful theory, thanks for taking the time to explain that Wilder Amps.

I've bleed the caps and cleaned the switches and it was all very uneventfull. I'm just waiting for it to all evaporate (the cleaner not my amp) before I put it all back together and plug in.

I did find some strange black stuff on one of my PCB's but I'm going to post it in the amps forum with a pic.

Anytime.

You can also use a can of compressed air to blow the contact cleaner out as well. Most contact cleaners are non-conductive so you shouldn't have to wait for it to evaporate before firing it up.

jcmjmp · 10-16-2009, 02:44 PM

Quote:

Originally Posted by Frankie

Maybe I'm missing something here, but if you clip the positive lead of a cap can to the chassis and that voltage has nowhere to go, doesn't that make the chassis the positive lead of the cap can which is holding 500vdc?

No. The energy is dissipated. With no resistor, you'll get a spark (you don't want that). With a resistor, when the current flows through, the energy is dissipated as heat. The energy is lost.

jcmjmp · 10-16-2009, 02:45 PM

Quote:

Originally Posted by Wilder Amplification

Also, much safer to do it with the amp unplugged so that you're not exposed to wall/mains voltage.

Definitely!

Wilder Amplification · 10-16-2009, 02:49 PM

Quote:

Originally Posted by andyman95023

Just curious if something like a light bulb would work in place of the resistor for a visual indication of draining

Thanks
Andy

If you wanna burn out the light bulb doing it, then yes.

Can anyone think of a lightbulb that's designed to run at 500VDC?

Also, that's what voltmeters are for.

PaoloJM · 10-16-2009, 04:56 PM

Quote:

Originally Posted by Frankie

Maybe I'm missing something here, but if you clip the positive lead of a cap can to the chassis and that voltage has nowhere to go, doesn't that make the chassis the positive lead of the cap can which is holding 500vdc?

You're trying to normalise the charge differential between the chassis and the + of the cap. Voltage doesn't "go" anywhere, you're just providing a path for current to flow so that the potential difference due to excess charge at each side of the cap is the same, and thus no voltage present.
The resistor simply reduces the amount of current flowing to a safe level that won't spark.
Once no potential difference is present between the temrinals then you can't be zapped.
Earth reference, or ground over the pond, has nothing to do with it, you're just trying to ensure that there is no excess charge in the cap to create the voltage between + and -.

MajorNut1967 · 10-17-2009, 12:17 AM

I'm glad there are a couple of you guys here who really know what you are talking about! Some of these people need not be giving out advice on how to open the Tooth paste tube even!

Wilder Amplification · 10-17-2009, 05:26 AM

Quote:

Originally Posted by MajorNut1967

I'm glad there are a couple of you guys here who really know what you are talking about! Some of these people need not be giving out advice on how to open the Tooth paste tube even!

Well since this has now been publicly voiced, and especially on a thread regarding tube amp power supplies and filter caps, I feel this needs to be said before someone either kills their amp or themselves...and I'm gonna be blunt because it's just in my nature to be so that being said -

While I realize that I'm a new member here, and in no way am I trying to degrade anyone or "toot my own horn" so to speak but I'm gonna have to say I agree 100% with this statement. Not just on this message board, but on others as well, I myself have witnessed certain posts giving out tech related advice when it's evident that the writer of said advice doesn't even know what it is they're posting. The worst has been from the guys trying to give tech advice after building their first amplifier, yet they themselves don't even know how to read a schematic!!! So in the interest of safety which is priority 1 when working on ANYTHING electrical...

When it comes to tube amps, you have anywhere from a 250 volt (Class A amps) to a 500+ volt supply in these amps and this poses a huge safety concern. For the sake of safety, in my opinion, unless you have a thorough (and I mean THOROUGH) understanding of basic electrical, electronics, and amp theory, the experience to back it up, and know what you're talking about, for the sake of others' safety you don't need to be giving out tech advice you know nothing about. Even though what you're saying may "make sense in your mind", you may be WAY off base and would never know it simply because you don't have a detailed understanding of the theory and don't have the experience to tell you otherwise. A lot of these guys are new to electronics and tube amps and while they have a genuine interest in learning tube amps and how they work, they don't yet have the ability to filter out the good and bad advice. Giving this advice out could mean someone's life...unless you're willing to have a person's blood on your hands, don't post tech advice that you yourself don't know anything about.

Also, unless you're talking about tone related stuff, you shouldn't post up the "I read somewhere that..." type of advice. Unless you yourself have tried it and have seen good results, don't post it. Again this goes along with the "don't post up tech advice unless you have a thorough understanding of electrical/amp theory, have the experience to back it up, and know what you're talking about."

I don't know if any of you here have been hit by the HT supply in a valve amp, but from experience I will say it is NOT fun in the least. In my early days of learning I've been literally knocked on my ass by a monster 620 volt supply...and I'm lucky that's all I got. I have a friend of mine who years ago in his early days got bit by a monster power supply from a Music Man amplifier (they're known for having their B+ be hotter than it needed to be) and basically was squirting blood all over the room and had to be rushed to the hospital. It was not pretty and this stuff is no joke.

Now my intent is NOT to scare people away from your amp in the least. Matter of fact, it's a very rewarding experience when you can learn to fix, maintain and mod your own shit. I'm just simply trying to explain the fact that safety needs to be PRIORITY #1 when working on these things, and there is definitely a safety issue here with inexperienced people who have a very limited grasp of electrical/amp theory and almost no experience giving out tech advice to those who are trying to learn how these things really work and would like some expert advice from those who really know what they're doing. "Going through the motions" of replacing parts and owning a DMM (Digital MultiMeter for those who don't know) DOES NOT make you a "qualified expert" in the least. You need some general understanding of electrical/electronic/amp theory to truly know what it is you're doing and be able to figure out on your own the things you should and shouldn't do with these amps before you give out any tech advice regarding them. I have seen people in the past post up "tech tips" that the pros have proven to be fatal to an amplifier, and they always have the "well I've been doing it and I haven't had any problems" defense...BECAUSE THEY SIMPLY DON'T KNOW ANY BETTER AND HAVE NO GRASP AS TO WHY THESE PRACTICES HAVE PROVEN TO CAUSE AMP FATALITY!!! Just because you HAVEN'T doesn't mean you WON'T. Notice...HAVEN'T = FUTURE TENSE...the problems are there, they just HAVEN'T haunted you YET. And there's always the "exception to the rule".

Myself and I'm sure the other gurus here on the site are more than willing to help and share our knowledge here with those who are willing to learn it. But it makes it harder to teach when there are others who don't know what they're talking about clouding the mix with misinformation and unsafe practices when you really don't know any better yet and have no way to sift through the bullshit. To add to that, it's very easy to become complacent when you've never been shocked since day one...after awhile your brain ends up saying to you "I have no idea what these people are talking about cause I've never been shocked". But trust me when I tell you the risk is very much there and if/when it happens it's not fun in the least. Becoming complacent when working on these things is not a good thing...never assume and never take anything for granted.

Now all that being said, the last thing I'll add is in regards to the massive piles of misinformation that I'm sure a lot of you have seen. Again this usually stems from those who don't have the knowledge or experience to know what to believe passing along information that either started out as mis-info right out the gate, or was mis-interpreted by the reader, yet they treat this mis-info like it's the bible. I can understand if you were to post up something like -

"I found this article regarding such-and-such and would like to get the experts' opinions on it"

This indicates that you don't know whether it's true or not, or that you don't fully understand what you read and you'd like to gain a thorough understanding of it. For the sake of your safety and the safety of others, this is MUCH better than posting it up in this fashion -

"I read on this site that such-and-such will do such-and-such. and because I read it, it's a good idea and you should do this."

When what you posted is NOT a good idea but since you don't know the electrical/amp theory and don't have the experience, you really don't know any better.

So for the sake of safety and for the sake of people not blowing up these expensive amplifiers, unless you really know what you're talking about, don't post up things that indicate that you have no idea what you're saying. It could mean someone's life. It's much better to hold back and not say anything rather than post up the wrong information and someone get hurt or killed over it.

Now just so you know, we weren't born with this knowledge. It wasn't given to us...we had to do LOTS of reading, experimenting to apply the knowledge, and asking the experts that were willing to share information (God knows those are hard to find in this industry). We definitely weren't "experts" overnight...it takes lots of time and dedication to gain a full understanding of how these things work. It's definitely something you have to earn...it just takes time and dedication...you definitely have to have a passion for it. You have to be willing to actually LEARN it rather than just want people to "give you all the answers". Hopefully myself as well as the other gurus on the board can give you a head start by breaking down in very simplified terms what we had to read over and over in complicated terms to understand.

If anyone was offended by my post, just know that I'm not sorry in the least and you need to get over it. I would much rather piss people off and step on toes/egos than sit back, not say anything to avoid pissing people off or hurting their egos, and watch them get hurt or killed because they believed the wrong information when I knew better and could've said something, but didn't all because I didn't want to step on toes. If I happen to step on toes or hurt someone's ego for the sake of saving a life, then so be it.

andyman95023 · 10-19-2009, 11:57 AM

Very well stated and true

Thanks Jon

P.S I tried to go to the website is it not ready yet?

Andyman95023

Wilder Amplification · 10-19-2009, 12:20 PM

Quote:

Originally Posted by andyman95023

Very well stated and true

Thanks Jon

P.S I tried to go to the website is it not ready yet?

Andyman95023

It should be working...at least it is on my end.

andyman95023 · 10-19-2009, 05:31 PM

Yes it sort of works. When clicking any of the commands it comes back with in valid address though?

Ok so a multi meter rated above 500 vdc will work good for cap draining and I feel better then doing any kind of spark shorting and yes I know unplugged and 1 hand behind the back. Will the meter take a bit longer to drain ?
I'm absorbing all the info you've been posting and always the safety precautions this really is serious sh*t.
Safety first save a buck secondary.

Thnx
Andyman95023

Wilder Amplification · 10-19-2009, 05:45 PM

Quote:

Originally Posted by andyman95023

Yes it sort of works. When clicking any of the commands it comes back with in valid address though?

Ok so a multi meter rated above 500 vdc will work good for cap draining and I feel better then doing any kind of spark shorting and yes I know unplugged and 1 hand behind the back. Will the meter take a bit longer to drain ?
I'm absorbing all the info you've been posting and always the safety precautions this really is serious sh*t.
Safety first save a buck secondary.

Thnx
Andyman95023

Yeah I'm still in the middle of building the site at the moment. Some of the pages aren't fully built yet. But I do have some of my products available in the store such as my JJ, SED Winged =C= valves as well as the Wilder Classic Classic amp and the THD HotPlates.

You misinterpreted the use of the meter.

The meter is not used to drain the caps. It is used to monitor the voltage stored in them so that you'll know when the charge has been bled off to a safe level.

The proper thing to use when draining is a piece of wire with alligator clips on the ends of it. With the amp off and unplugged, you clip one end to the chassis and the other end to pin #1 of the first preamp tube. This uses the power supply dropping resistors in the amp as a discharge path. You then connect the meter to the HT fuse and watch the voltage there with the amp off...the voltage there will tell you how much of a charge is left on the caps.

Leave the jumper wire in place while you're working on the amp so that the caps can't develop a "memory" and rebuild their charge while you're working on it. Remember to remove the jumper before powering up.

MartyStrat54 · 10-19-2009, 06:10 PM

I'm glad you came back and straightened out Andy. I was reading all of this and then I see that he is going to use his MM to drain caps. Thanks for all of the info. I've seen the destructive force of high DC voltages. Even 270VAC that you find in commercial electricity will knock you off a ladder. I agree that there are probably people giving advice that shouldn't. I have a military electronics background, but even so, I'm smart enough to know when I am in need of assistance. If it's too complicated, I take it to the tech.

Wilder Amplification · 10-19-2009, 06:22 PM

Quote:

Originally Posted by MartyStrat54

I have a military electronics background

What branch were you in? I did 4 years Navy as an avionics tech from '98-'02.

Yeah...trying to use a MM to drain caps would take YEARS. I've used the alligator jumper trick mentioned above since I've started. The dropping resistors in the power supply are a high enough value to where not much current will flow all at once and shock discharge, yet still bleed the charge off within a minute or two.

MartyStrat54 · 10-19-2009, 07:04 PM

I'm a Viet Nam "era" vet. Meaning the war was basically over with. I was in the Air Force for six years. I worked on specialized electronics on U-2 and SR-71 spy planes and did some stints with NSA. Late 74 to early 80.

Wilder Amplification · 10-19-2009, 07:07 PM

Quote:

Originally Posted by MartyStrat54

I'm a Viet Nam "era" vet. Meaning the war was basically over with. I was in the Air Force for six years. I worked on specialized electronics on U-2 and SR-71 spy planes and did some stints with NSA. Late 74 to early 80.

Ah OK...that was before my time (born in '79).

I did all F/A-18 electronic weapons system stuff.

MartyStrat54 · 10-19-2009, 07:16 PM

Quote:

Originally Posted by Wilder Amplification

Yeah...trying to use a MM to drain caps would take YEARS. I've used the alligator jumper trick mentioned above since I've started. The dropping resistors in the power supply are a high enough value to where not much current will flow all at once and shock discharge, yet still bleed the charge off within a minute or two.

Yes I've seen that technique before and it works nicely. I would recommend it over using a raw resistor and an alligator clip. Some people do this and still get a "POP" when they use the wrong value resistor to bleed off filter caps. (Then their elbow flies into the power tranny and they chip the bone.) See, you can get hurt and not even get shocked.

andyman95023 · 10-20-2009, 09:30 AM

Quote:

Originally Posted by MartyStrat54

Yes I've seen that technique before and it works nicely. I would recommend it over using a raw resistor and an alligator clip. Some people do this and still get a "POP" when they use the wrong value resistor to bleed off filter caps. (Then their elbow flies into the power tranny and they chip the bone.) See, you can get hurt and not even get shocked.

Thank you guys for all the great info and the "POP" is what I'm looking to avoid.
So should these alligator clips be insulated as it seems clipping a metal clip onto pin 1 exposes the hand to a possible charge.

Thanks again
Andyman95023
P.S I know a MM is for monitoring but curious as to its use as a cap drain and now I get the picture.

Wilder Amplification · 10-20-2009, 12:36 PM

Quote:

Originally Posted by andyman95023

Thank you guys for all the great info and the "POP" is what I'm looking to avoid.
So should these alligator clips be insulated as it seems clipping a metal clip onto pin 1 exposes the hand to a possible charge.

Thanks again
Andyman95023
P.S I know a MM is for monitoring but curious as to its use as a cap drain and now I get the picture.

Yeah the internal resistance of a MM is way too high to use it as a current drain, which is why it would take years to drain them by itself.

As far as the insulated alligator clips, yes that would be a good idea. You can buy them at any electronics store and they're pretty inexpensive. They usually sell them in multiple amounts.

You shouldn't get much of a spark if any at all by clipping to pin 1 as not much current can flow all at once due to the value of the dropping resistors in the power supply.

Frankie · 10-20-2009, 03:04 PM

Well right on, you learn something new every day! I always left my amp grounded when working on it.

10-16-2009, 10:33 AM	#1 (permalink)
Valentine Smith Junior Member Join Date: Aug 2009 Location: Lisbon Posts: 11	earth the chassis when draining filter caps? Hi, Later on I'm going to clean my switches and tube sockets on my SL-X 2500 and like a good boy first I'm going to drain the filter caps with my newly made 2 croc clips with a resistor in the middle device by clipping one end to the chassis and then touching the other clip to the caps contacts for a few seconds. (one hand behind the back) But my question is I'm going to do this on my wooden kitchen table so do I also have to have the chassis connected to a good ground point at the same time or is good enough to drain to the chassis just sitting isolated on the kitchen table?

10-16-2009, 10:46 AM	#2 (permalink)
jcmjmp Senior Member Join Date: Nov 2008 Posts: 1,341	Re: earth the chassis when draining filter caps? No need to ground the chassis. The energy is dissipated through the resistor.

10-16-2009, 11:39 AM	#5 (permalink)
Frankie Senior Member Join Date: Sep 2007 Location: Clearwater, FL Posts: 362	Re: earth the chassis when draining filter caps? I always ground mine. I don't know about you, but I don't wanna chance a bum resistor and find out I have a 500 volt chassis when I touch it. Is it really that hard to plug the thing in? __________________ w w w . c o w b o y m a f i a . n e t Myspace.com \| YouTube \| Facebook

10-16-2009, 12:37 PM	#8 (permalink)
andyman95023 Junior Member Join Date: Apr 2009 Location: Hollister Ca Posts: 19	Re: earth the chassis when draining filter caps? Just curious if something like a light bulb would work in place of the resistor for a visual indication of draining Thanks Andy

10-16-2009, 02:04 PM	#11 (permalink)
Valentine Smith Junior Member Join Date: Aug 2009 Location: Lisbon Posts: 11	Re: earth the chassis when draining filter caps? Thanks very much for the advice. And I also learnt some useful theory, thanks for taking the time to explain that Wilder Amps. I've bleed the caps and cleaned the switches and it was all very uneventfull. I'm just waiting for it to all evaporate (the cleaner not my amp) before I put it all back together and plug in. I did find some strange black stuff on one of my PCB's but I'm going to post it in the amps forum with a pic.

10-17-2009, 12:17 AM	#17 (permalink)
MajorNut1967 Senior Member Join Date: Jul 2009 Location: South Pacific Posts: 710	Re: earth the chassis when draining filter caps? I'm glad there are a couple of you guys here who really know what you are talking about! Some of these people need not be giving out advice on how to open the Tooth paste tube even! __________________ MJN1967 aka BA (Bad Attitude) 1968 model 1987 50watt. A Baby Major (Half-Power) I built from the ground up. JTM 45 Clone combo Ground up build. JCM 800 Clone Ground up build. Custom Built Warmoth Strat 75' Fender Tele-Deluxe '70 style strat custom build w/Custom Shop 69's PU's

10-19-2009, 11:57 AM	#19 (permalink)
andyman95023 Junior Member Join Date: Apr 2009 Location: Hollister Ca Posts: 19	Re: earth the chassis when draining filter caps? Very well stated and true Thanks Jon P.S I tried to go to the website is it not ready yet? Andyman95023

10-19-2009, 05:31 PM	#21 (permalink)
andyman95023 Junior Member Join Date: Apr 2009 Location: Hollister Ca Posts: 19	Re: earth the chassis when draining filter caps? Yes it sort of works. When clicking any of the commands it comes back with in valid address though? Ok so a multi meter rated above 500 vdc will work good for cap draining and I feel better then doing any kind of spark shorting and yes I know unplugged and 1 hand behind the back. Will the meter take a bit longer to drain ? I'm absorbing all the info you've been posting and always the safety precautions this really is serious sh*t. Safety first save a buck secondary. Thnx Andyman95023

10-19-2009, 06:10 PM	#23 (permalink)
MartyStrat54 Senior Member Join Date: Feb 2009 Location: Formerly Phoenix, now north of KC Posts: 2,583	Re: earth the chassis when draining filter caps? I'm glad you came back and straightened out Andy. I was reading all of this and then I see that he is going to use his MM to drain caps. Thanks for all of the info. I've seen the destructive force of high DC voltages. Even 270VAC that you find in commercial electricity will knock you off a ladder. I agree that there are probably people giving advice that shouldn't. I have a military electronics background, but even so, I'm smart enough to know when I am in need of assistance. If it's too complicated, I take it to the tech. __________________ MARTY 2009 Gibson Explorer-Hell Raising Machine 1989 Fender Strat Plus USA 2008 Fender Tele USA 2004 Schecter Elite w/DiMarzio's TSL100 with custom 4x12 cab. TSL122 with Man 'O War Speakers. TSL602 #1 with JBL D123 Speakers and 602 #2 with Altec 417 Speakers. "Oh so sweet my friends." DSL401 #1 with Red Fang Speaker and 401 #2 with JBL D123 Speaker. Tubes: Let's just say they are NOS that kick ass.

10-19-2009, 07:04 PM	#25 (permalink)
MartyStrat54 Senior Member Join Date: Feb 2009 Location: Formerly Phoenix, now north of KC Posts: 2,583	Re: earth the chassis when draining filter caps? I'm a Viet Nam "era" vet. Meaning the war was basically over with. I was in the Air Force for six years. I worked on specialized electronics on U-2 and SR-71 spy planes and did some stints with NSA. Late 74 to early 80. __________________ MARTY 2009 Gibson Explorer-Hell Raising Machine 1989 Fender Strat Plus USA 2008 Fender Tele USA 2004 Schecter Elite w/DiMarzio's TSL100 with custom 4x12 cab. TSL122 with Man 'O War Speakers. TSL602 #1 with JBL D123 Speakers and 602 #2 with Altec 417 Speakers. "Oh so sweet my friends." DSL401 #1 with Red Fang Speaker and 401 #2 with JBL D123 Speaker. Tubes: Let's just say they are NOS that kick ass.

10-20-2009, 03:04 PM	#30 (permalink)
Frankie Senior Member Join Date: Sep 2007 Location: Clearwater, FL Posts: 362	Re: earth the chassis when draining filter caps? Well right on, you learn something new every day! I always left my amp grounded when working on it. __________________ w w w . c o w b o y m a f i a . n e t Myspace.com \| YouTube \| Facebook

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