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Post subject: Sprague ATOM caps tolerance values questions..
Posted: Thu Nov 28, 2019 7:31 am
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I'm recaping a 1966 Bandmaster Blackface with AB763 chassis.
I checked the available Electrolytic recaping kits and
I found the F&T company used for many techs as a replacement
for vintage Fender amps, but I already had Sprague on hand..
So before installing any I measured all of them.
The 2 x 100uf/350v tested at around 120uf (+20%) --- (Sprague specs them -10% +75% tolerance)
The 3 x 20uf/500v tested at around 29uf (+45%) --- (Sprague specs them -10% +50% tolerance)
The 5 x 25uf/25v tested at around 30uf (+20%) --- (Sprague specs them 20% tolerance)
The only 100uf/100v BIAS cap tested at around 120uf (+20%) --- (Sprague specs them 20% tolerance)

I find the 20uf/500v +45% high for a manufacturer part..
Are they OK for my Bandmaster Blackface recaping ?


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Post subject: Re: Sprague ATOM caps tolerance values questions..
Posted: Thu Nov 28, 2019 11:03 am
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What the tolerance is at operating temp often determines how well they filter. Not, static, room temp measurements.

How long have these Atoms been sitting on a shelf? That counts. Do they have yellow, blue, or black outer covers? Yellow is the oldest of the plastic wrapped versions --- can be as old as the 1970s. It should have the EIA code somewhere on the label. "303" (Sprague's EIA code), followed by 3-4 digits to indicate year-month or year-week made.

AFAIK, light blue and black are modern (at least this century made) Sprague 'lytics.

You have any photos of this stock? Thanks!

:mrgreen:


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Post subject: Re: Sprague ATOM caps tolerance values questions..
Posted: Thu Nov 28, 2019 12:56 pm
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BMW2002Ti wrote:
What the tolerance is at operating temp often determines how well they filter. Not, static, room temp measurements.

How long have these Atoms been sitting on a shelf? That counts. Do they have yellow, blue, or black outer covers? Yellow is the oldest of the plastic wrapped versions --- can be as old as the 1970s. It should have the EIA code somewhere on the label. "303" (Sprague's EIA code), followed by 3-4 digits to indicate year-month or year-week made.

AFAIK, light blue and black are modern (at least this century made) Sprague 'lytics.

You have any photos of this stock? Thanks!

:mrgreen:


They are pretty new.
Since there was no reply about installing them or not I decided to give them a try..

Here is a picture of all of them just installed in the Bandmaster Blackface:
http://www.arcenson.com/public/Just_ins ... M_caps.JPG


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Post subject: Re: Sprague ATOM caps tolerance values questions..
Posted: Thu Nov 28, 2019 1:04 pm
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Good job! You have a Variac, to ramp them up the first time? Just to avoid any miss-wiring disasters.

Those caps and metal oxide resistors should last to mid-21st century! :)


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Post subject: Re: Sprague ATOM caps tolerance values questions..
Posted: Thu Nov 28, 2019 2:05 pm
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What do you use to read those caps ?


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Post subject: Re: Sprague ATOM caps tolerance values questions..
Posted: Thu Nov 28, 2019 3:12 pm
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stratele52 wrote:
What do you use to read those caps ?


I have 3 different caps testers. All are cheapo chinese digital types.
Compared, they measured all the same caps values.
And I checked these meters with 1% tolerance caps
and they gave me good readings, so noo problem with that..

Here is my final rig..:
Bandmaster connected to my 2 x DIY rotary speaker cabinets
(loaded with Eminence Legend 1058 - 10" 8ohms in each cabinet)
http://www.arcenson.com/public/My_final_rig.JPG

I was expecting a pretty good sound out of this.
It was AMAZINGLY GOOD !!
The last 2 extensive days of restoring finally pay off.
Very happy !


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Post subject: Re: Sprague ATOM caps tolerance values questions..
Posted: Thu Nov 28, 2019 5:34 pm
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Nice rig!

Do you have those two rotors sync'd together?

Arjay

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"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


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Post subject: Re: Sprague ATOM caps tolerance values questions..
Posted: Thu Nov 28, 2019 5:45 pm
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Retroverbial wrote:
Nice rig!

Do you have those two rotors sync'd together?

Arjay


No, These are leslie modules ripped from old Hammond and Yamaha organs.
They have different slow/fast speeds but they are very close.
This creates a very nice kind of stereo waving sound..
And the time both cabinets change speed is a little different
for each of them. Very interesting results.
I switch both cabinet speeds SLOW/FAST or STOP using an internal CPU card
talking to a remote pedal across a standard mic XLR 3 wires cable that makes speed changes on both cabinets.
I love that spinning sound !


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Post subject: Re: Sprague ATOM caps tolerance values questions..
Posted: Thu Nov 28, 2019 7:46 pm
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I imagine it makes for a great "Badge" tone!

Arjay

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"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


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Post subject: Re: Sprague ATOM caps tolerance values questions..
Posted: Fri Nov 29, 2019 2:52 am
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jpdesroc wrote:
stratele52 wrote:
What do you use to read those caps ?


I have 3 different caps testers. All are cheapo chinese digital types.
Compared, they measured all the same caps values.
And I checked these meters with 1% tolerance caps
and they gave me good readings, so noo problem with that..

!


What is your % tolerance / precision of your meter ?
You can't trust cheap meter to write reading in forum where it can be misinterpreted by those who read us and do not know anything about it.

I have a Meterman LCR55 and Fluke 175 these are not cheap meters.

Test 2 Sprague 10 mfd , 150 Vdc; one reading 9.99 mfd, other 10.3 mfd
Test 5 Sprague 10 mfd 50 dc volts reading between 11 and 11.7 mfd Reading with Fluke 175 ; 10.4 , 10.7 mfd
Test 7 Sprague 25 MFD 25 vdc ; they are all close to 5 % tolerance Reading with Fluke 175 all less 5%
test 2 Sprague 100 mfd 450 volts one is 92.5 and other are 89 mfd Fluke 175 96.1, 101 mfd
Test 2 Sprague 40 mfd 450 v ; 45.2 and 44.6 mfd Fluke 175 ; 45.8, 46.6
20 mfd 500 v test 22.9 mfd
test 2 Sprague 16 mfd 475 V ; 18 and 18 mfd Fluke 175 18.7, 18.8mfd

My conclusion is that the Sprague that I was able to check are capacitors whose advertised values are reliable


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Post subject: Re: Sprague ATOM caps tolerance values questions..
Posted: Fri Nov 29, 2019 9:23 am
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stratele52 wrote:
jpdesroc wrote:
stratele52 wrote:
What do you use to read those caps ?


I have 3 different caps testers. All are cheapo chinese digital types.
Compared, they measured all the same caps values.
And I checked these meters with 1% tolerance caps
and they gave me good readings, so noo problem with that..

!


What is your % tolerance / precision of your meter ?
You can't trust cheap meter to write reading in forum where it can be misinterpreted by those who read us and do not know anything about it.

I have a Meterman LCR55 and Fluke 175 these are not cheap meters.

Test 2 Sprague 10 mfd , 150 Vdc; one reading 9.99 mfd, other 10.3 mfd
Test 5 Sprague 10 mfd 50 dc volts reading between 11 and 11.7 mfd Reading with Fluke 175 ; 10.4 , 10.7 mfd
Test 7 Sprague 25 MFD 25 vdc ; they are all close to 5 % tolerance Reading with Fluke 175 all less 5%
test 2 Sprague 100 mfd 450 volts one is 92.5 and other are 89 mfd Fluke 175 96.1, 101 mfd
Test 2 Sprague 40 mfd 450 v ; 45.2 and 44.6 mfd Fluke 175 ; 45.8, 46.6
20 mfd 500 v test 22.9 mfd
test 2 Sprague 16 mfd 475 V ; 18 and 18 mfd Fluke 175 18.7, 18.8mfd

My conclusion is that the Sprague that I was able to check are capacitors whose advertised values are reliable


Here are the 4 meters I used to measure all the Sprague caps.
I forgot to ad my very good Fluke V meter in the list
and the K2574 ESR meter..

FLUKE 87V meter (capacitance read mode)
https://www.toolup.com/Fluke-87-5-Fluke ... Multimeter

LC200A meter (capacitance read mode)
https://ebay.us/FMVoJM

Digital LC100-A LCD High Precision Inductance Capacitance L/C Meter Tester
https://ebay.us/hAbIK4

ALTRONICS K2574 ESR meter
https://www.altronics.com.au/p/k2574-esr-meter-kit/

I did some other test on good ESR electrolytic caps I had on hand
and see the results:

-----------------------Sprague ATOM---Sprague ATOM---MIEC------------Sprague ATOM---Sprague ATOM
-----------------------80uf/450v----------80uf/450v----------22uf/450v----10uf/450v----------10uf/450v

FLUKE 87V--------92.5uf----------------97.4uf--------------21.8uf----------10.2uf---------------10.5uf
LC200A------------85.0uf----------------92.1uf--------------20.0uf----------9.97uf---------------9.82uf
Chinese tester---90.7uf----------------94.3uf--------------22.3uf----------10.6uf---------------10.4uf

ALTRONICS-----.38 ohm-------------.30 ohm------------1.5 ohm-------4.0 ohm------------4.1 ohm
K2574 ESR meter

So... I think my yesterday's readings were correct..
JP


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Post subject: Re: Sprague ATOM caps tolerance values questions..
Posted: Sat Nov 30, 2019 7:08 am
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Your samples seems well within tolerance. Good to go!


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Post subject: Re: Sprague ATOM caps tolerance values questions..
Posted: Sat Nov 30, 2019 1:12 pm
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BMW2002Ti wrote:
Your samples seems well within tolerance. Good to go!


+1 :)


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Post subject: Re: Sprague ATOM caps tolerance values questions..
Posted: Mon Dec 02, 2019 3:27 pm
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See yesterday on a trip in LaGrange, Alabama. Georgia Radio Museum.


ImageDSC07619 by


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Post subject: Re: Sprague ATOM caps tolerance values questions..
Posted: Mon Dec 02, 2019 7:10 pm
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The thing to watch on tolerance is if they are reading high, make note of how long it takes to get a reading compared to a new cap of the same value.
coupling caps will eventually start to leak, which will allow DC to pass through to the next stage... not a good thing.
The leakage acts like a parallel resistance, so it will cause the cap to take a bit longer to charge, and will show higher than rated. This may or may not show on an ohmmeter.
If it's starting to approach the limits of spec on the high side, it may be time to replace it.

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