How often should I power them up?

TPR · 10-17-2009, 12:32 PM

I have 3 functional amps and one I'm working on and hope to have up and running soon. Let's say, hypothetically, that I play the marshall every day and not so much through the others

I understand that if the caps drain and then get hit with power, that's bad over time. So, how often should I turn them on and for how long (give or take)? Thanks.

Sir Don · 10-17-2009, 09:47 PM

Bump for this one, I'm curious too.

Wilder Amplification · 10-17-2009, 10:05 PM

Six months is the absolute limit on this. As a matter of practice, I'd do it once a month or so.

riffdrive · 10-17-2009, 10:46 PM

I'd be interested as well to hear from some honest-to-goodness amp techs on this, but I normally try to power up tube amps I don't use every month or so.

I think a lot of it might be influenced by the climate and humidity that the amp in question sees on a daily basis. I.E. if you live in Death Valley, your caps will likely dry out sooner than if you live in the tropics.

Then again, if you're living in Death Valley, you've probably got bigger problems than the caps in your Marshall drying out :P

Wilder Amplification · 10-17-2009, 10:54 PM

Quote:

Originally Posted by riffdrive

I'd be interested as well to hear from some honest-to-goodness amp techs on this, but I normally try to power up tube amps I don't use every month or so.

I think a lot of it might be influenced by the climate and humidity that the amp in question sees on a daily basis. I.E. if you live in Death Valley, your caps will likely dry out sooner than if you live in the tropics.

Then again, if you're living in Death Valley, you've probably got bigger problems than the caps in your Marshall drying out :P

What happens is that when caps are brand new, the dielectric has to "form". There is a high leakage through the dielectric where current can pass through the dielectric, hence the reason why we form caps that are brand new. When caps are "formed", it forms a film that the electrons cannot flow through.

Overtime, this film layer that is formed on the dielectric to keep the electrons from "leaking through" deteriorates when no power is applied for a long time period. When you all of a sudden "shock the cap" with high voltage after this film has deteriorated, you risk damaging the dielectric and shorting the cap.

TPR · 10-17-2009, 11:26 PM

Great, thanks for the info. I think I can handle once a month. For that matter, I can really baby them and turn them on once every couple of weeks.

Is it enough just to turn them on for a few minutes, or is it better to play through them a bit?

And is it better for them for me to play the Jimi riffs or the Angus riffs? Yeah, yeah, I already know the answer to that one. "You can't play either one, so just sell the amps and shut up about it."

Wilder Amplification · 10-17-2009, 11:46 PM

Quote:

Originally Posted by TPR

Great, thanks for the info. I think I can handle once a month. For that matter, I can really baby them and turn them on once every couple of weeks.

Is it enough just to turn them on for a few minutes, or is it better to play through them a bit?

And is it better for them for me to play the Jimi riffs or the Angus riffs? Yeah, yeah, I already know the answer to that one. "You can't play either one, so just sell the amps and shut up about it."

LOL that's funny shit right there.

A few minutes is fine...you don't even have to play through it. It just has to be on with the standby switch set to "play" mode. Make sure you hook it to a speaker cab though.

T-Bird · 10-18-2009, 02:40 AM

Hi.

Yep, as answered already, once a month is quite enough. If You have a vari-ac, the period between power-ups can be as long as You like.

It's really sad to see that quite a few people in the tube amp circles are somewhat familiar with the care of the tubes, but caps are still regarded as maintenance free. Maintenance in this case being the occasional use.

A good topic, perhaps this'll increase the awarness a bit.

Regards
Sam

Wilder Amplification · 10-18-2009, 02:52 AM

Quote:

Originally Posted by T-Bird

Hi.

Yep, as answered already, once a month is quite enough. If You have a vari-ac, the period between power-ups can be as long as You like.

It's really sad to see that quite a few people in the tube amp circles are somewhat familiar with the care of the tubes, but caps are still regarded as maintenance free. Maintenance in this case being the occasional use.

A good topic, perhaps this'll increase the awarness a bit.

Regards
Sam

Instead of using the variac, another trick I know of to form caps is to install a 100K resistor between the positive side of the rectifier and the first filter cap, then monitor the voltage drop across this resistor with a DMM as the caps form. Once it's down to 5 volts or less, the caps are formed and you can then remove the resistor.

JohnH · 10-18-2009, 04:17 AM

Interesting stuff Jon and others. So presumably this could apply to any equipment with large electrolytics as filter caps? Or is it just for HT gear such as tube amps? is there a smaller size of cap below which you dont need to worry? And if a cap is left for many years, is there a time after which it is unlikely to be retrievable by slow power up?

cheers

John

T-Bird · 10-18-2009, 05:17 AM

Hi.

Quote:

Originally Posted by Wilder Amplification

Instead of using the variac, another trick I know of to form caps is to install a 100K resistor between the positive side of the rectifier and the first filter cap, then monitor the voltage drop across this resistor with a DMM as the caps form. Once it's down to 5 volts or less, the caps are formed and you can then remove the resistor.

Thanks Jon, didn't think of that.

Fortunately I've always had a variac as I found an old 2KW "dimmer unit" back in the day when I was starting out. Just a largish 2KW variable resistor really

.
Been using that ever since for all "soft starts". Not ideal, but gets the job done.

Been using that for another application that You can probably guess as well, but as it's not recommended by anyone I'll leave it at that...

John, IMLE all the electrolytic caps that have not been used for a while will benefit from the "soft start" as the physics and chemistry is about the same regardless of the size.
The higher voltage ones obviously are the ones which we are concerned with, as those are the ones in the power supply and are the most expensive ones.

On a circuit, there's usually a "soft start" by design so those caps are less likely to suffer.

If there's no visible damage on an el-cap, virtually all can be revived/reformed. IMLE again.

Regards
Sam

Wilder Amplification · 10-18-2009, 12:58 PM

Quote:

Originally Posted by T-Bird

Hi.

Thanks Jon, didn't think of that.

Fortunately I've always had a variac as I found an old 2KW "dimmer unit" back in the day when I was starting out. Just a largish 2KW variable resistor really

.
Been using that ever since for all "soft starts". Not ideal, but gets the job done.

Been using that for another application that You can probably guess as well, but as it's not recommended by anyone I'll leave it at that...

John, IMLE all the electrolytic caps that have not been used for a while will benefit from the "soft start" as the physics and chemistry is about the same regardless of the size.
The higher voltage ones obviously are the ones which we are concerned with, as those are the ones in the power supply and are the most expensive ones.

On a circuit, there's usually a "soft start" by design so those caps are less likely to suffer.

If there's no visible damage on an el-cap, virtually all can be revived/reformed. IMLE again.

Regards
Sam

Well...and the reason I recommend the resistor method is as you very well know, there are just some people that shouldn't own certain things for certain reasons (i.e. variacs) just as well, there are certain bits of information you just should not share with certain people, if for nothing else for their own well being.

And as far as the other thing you mentioned...you're already well aware of the risks involved so nothing more needs to be said there.

There is a saying that goes "What is understood need not be discussed"...believe me, that statement has a lot more meaning than one would think.

TPR · 10-18-2009, 02:36 PM

Quote:

Originally Posted by Wilder Amplification

A few minutes is fine...you don't even have to play through it. It just has to be on with the standby switch set to "play" mode. Make sure you hook it to a speaker cab though.

Good point. Of course I understand about needing the speaker cab, but I could see accidentally firing up one of the heads without thinking about it, so good catch on that.

Plenty of excellent info. Thanks to all.

10-17-2009, 12:32 PM	#1 (permalink)
TPR Senior Member Join Date: Sep 2009 Posts: 109	How often should I power them up? I have 3 functional amps and one I'm working on and hope to have up and running soon. Let's say, hypothetically, that I play the marshall every day and not so much through the others I understand that if the caps drain and then get hit with power, that's bad over time. So, how often should I turn them on and for how long (give or take)? Thanks. __________________ The awesome tone coming out of my amp almost makes up for my inability to play. '91 JCM 900 Head w/ EL34s '68 Bassman Head- Blackfaced Hand Built 2x12 Classic 30 Gibson LP Studio w/ PAFs Epi LP Standard w/ G 57s The usual assortment of pedals and stuff

10-17-2009, 09:47 PM	#2 (permalink)
Sir Don Senior Member Join Date: Aug 2009 Location: Adelaide, South Australia Posts: 139	Re: How often should I power them up? Bump for this one, I'm curious too. __________________ My gear: 2204, 2210, 2555, 9005, 1959, 5005, 4103, 2100, TSL100 www.myspace.com/rockthebosss

10-17-2009, 10:46 PM	#4 (permalink)
riffdrive Senior Member Join Date: Jan 2009 Location: north Georgia mountains Posts: 204	Re: How often should I power them up? I'd be interested as well to hear from some honest-to-goodness amp techs on this, but I normally try to power up tube amps I don't use every month or so. I think a lot of it might be influenced by the climate and humidity that the amp in question sees on a daily basis. I.E. if you live in Death Valley, your caps will likely dry out sooner than if you live in the tropics. Then again, if you're living in Death Valley, you've probably got bigger problems than the caps in your Marshall drying out :P __________________ ----------------------------------------------------------- 2001 Marshall DSL 50 (JJ ECC83, Svetlana EL34) 2005 Marshall Mode Four Avatar 2x12 (1x Vintage 30, 1x Greenback) Peavey 4x12 (Sheffield 1290) Taylor Standard Solidbody Ibanez RG2EX2

10-17-2009, 11:26 PM	#6 (permalink)
TPR Senior Member Join Date: Sep 2009 Posts: 109	Re: How often should I power them up? Great, thanks for the info. I think I can handle once a month. For that matter, I can really baby them and turn them on once every couple of weeks. Is it enough just to turn them on for a few minutes, or is it better to play through them a bit? And is it better for them for me to play the Jimi riffs or the Angus riffs? Yeah, yeah, I already know the answer to that one. "You can't play either one, so just sell the amps and shut up about it." __________________ The awesome tone coming out of my amp almost makes up for my inability to play. '91 JCM 900 Head w/ EL34s '68 Bassman Head- Blackfaced Hand Built 2x12 Classic 30 Gibson LP Studio w/ PAFs Epi LP Standard w/ G 57s The usual assortment of pedals and stuff

10-18-2009, 02:40 AM	#8 (permalink)
T-Bird Senior Member Join Date: Jul 2009 Location: Finland (Northern Europe) Posts: 151	Re: How often should I power them up? Hi. Yep, as answered already, once a month is quite enough. If You have a vari-ac, the period between power-ups can be as long as You like. It's really sad to see that quite a few people in the tube amp circles are somewhat familiar with the care of the tubes, but caps are still regarded as maintenance free. Maintenance in this case being the occasional use. A good topic, perhaps this'll increase the awarness a bit. Regards Sam

10-18-2009, 04:17 AM	#10 (permalink)
JohnH Senior Member Join Date: May 2008 Location: Wollongong NSW Posts: 640	Re: How often should I power them up? Interesting stuff Jon and others. So presumably this could apply to any equipment with large electrolytics as filter caps? Or is it just for HT gear such as tube amps? is there a smaller size of cap below which you dont need to worry? And if a cap is left for many years, is there a time after which it is unlikely to be retrievable by slow power up? cheers John __________________ DSL401 8412 cab Crate Powerblock 1 x 12 Vintage 30 cab '76 Shergold Masquerader '93 Les Paul Studio '83 Roadstar

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