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Stupid Capacitor Reform Question


artto

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I have several SET amps, all with tube rectifiers. The amps haven't been used in approximately 12+ months. They are all relatively new (< 2yrs old).

 

Do I need to fire up these amps slowly with a variac to reform the caps if they have a tube rectifier?

 

 

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Thanks guys!

 

I was just hoping that having a tube rectifier might alleviate the need to pull out the variac.

 

So variac it is. 

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On 1/9/2023 at 2:28 PM, artto said:

I have several SET amps, all with tube rectifiers. The amps haven't been used in approximately 12+ months. They are all relatively new (< 2yrs old).

 

Do I need to fire up these amps slowly with a variac to reform the caps if they have a tube rectifier?

 

 

 

Just power them on and enjoy.

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On 1/9/2023 at 3:28 PM, artto said:

I have several SE

The Tube Recto comes up slowly anuwaysmps, all with tube rectifiers. The amps haven't been used in approximately 12+ months. They are all relatively new (< 2yrs old).

 

Do I need to fire up these amps slowly with a variac to reform the caps if they have a tube rectifier?

 

 

No Letter rip   ..the Tube Recto comes up slowly anyways

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Electrolytics age while under load.  The life expectancy of an electrolytic (say 4000h) is based on it operating typically at 2x its max. continuous ripple current and max temperature (usually 105C).  Temperature is the big driver.  Most electrolytics are rated to 105C max (220F) which is quite hot and sitting at that temperature with no power will shorten life.  

 

In real world circuits, electrolytics rarely exceed 40C and, at design ripple current, will last much, much longer.

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So, how slowly do you guys increase the voltage when reforming caps on a reasonably new tube amp ( <10 years old) that hasn't been turned on for more than a year?

 

AND, how slowly do you guys increase the voltage when reforming caps on a old tube amp ( 30+ years old) that hasn't been turned on for more than a year?

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9 minutes ago, tigerwoodKhorns said:

 

Yea, I am updating my electronic tools lately as I have several amps that are due for caps and refresh and I need to brush up on my skills with these. 

 

So any scope? 

 

 

 

 

Yeah there are some cool ones out there I have HP, Tektronix, and a sencore. The sencore is cool because it can measure voltage at the same time but  you wouldn't want to tie up that scope for one purpose. I really like the tektronix scopes. There are lots of them and they are affordable.

 

I am rebuilding my workbench from scratch which should be fun.... lol scary.....

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I have a number of scopes and like Seti really like my old analog scopes. Crap shoot finding a good working one but when you do you will love the trace it provides. Still I probably use my digital scope more being it is so easy to get numbers. Nothing fancy for me, a Hantek DSO5102 is plenty good enough for audio work. 

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Here is what I used to setup as curve tracer. Being able to step through caps and parts while in circuit is invaluable tool.

 

Here is a terrible pic of mine.

IMG_7883.thumb.JPG.b1833cc6d7e24f9adc86e259a96a9929.JPG

 

It is also fun to restore scopes of course it helps to have one as a curve tracer to start with....

 

Check your craigslist I bet there are a handful to choose from.

 

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8 minutes ago, seti said:

Here is what I used to setup as curve tracer. Being able to step through caps and parts while in circuit is invaluable tool.

 

Here is a terrible pic of mine.

IMG_7883.thumb.JPG.b1833cc6d7e24f9adc86e259a96a9929.JPG

 

It is also fun to restore scopes of course it helps to have one as a curve tracer to start with....

 

Check your craigslist I bet there are a handful to choose from.

 

Now that is an old one for sure. I have 6 or so old scopes but none that old. My repairs of old scopes has been hit or miss. Most times it is a power supply problem though. 

 

But getting back to reforming old caps, unless the equipment is decades old I do not go through the trouble myself. Does not hurt to be too careful though. To answer the how question, slowly bring the power up to approximately 60V's and hold it awhile there then slowly bring it up to line voltage from there. 

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