• The move to the new server is done. There are some software and database maintenance updates in process. This has us passing the hat around to help out. We appreciate any donations. Seriously, even a dollar helps. The payment page may be found here - https://www.audiokarma.org/support.html

Scott 222C

thefragger said:
Thank you :)

Quick question--is it normal for that cap in the centre of all the tubes to get moderately warm? I think it's okay since it's surrounded by tubes, but just wanted to ask.
Click to expand...

My 222C has the same JJ's replacements for the can caps and that center one does pick up some heat after being on for awhile. Lukewarm is how I'd describe it but not "hot" like the PT gets or anything.
 
Hi,
Those bottles look real nice, and yes that middle cap does get warm, if you
hold your hand over the amp when it's on, you feel the heat from all those tube's rising
and it's pretty warm!
 
thefragger said:
Thank you :)

Quick question--is it normal for that cap in the centre of all the tubes to get moderately warm? I think it's okay since it's surrounded by tubes, but just wanted to ask.
Click to expand...

yup normal...the longer you run the amp the warmer everything will get to a point. The right channel output transformer always gets hotter then the left channel for the same reason.
 
Wow, I go away for a couple weeks and you two have filled a couple pages. Nice work. Glad to see it running. Nice photos too.
 
thefragger said:
--snip--And then that dinky 1A fuse in the VARIC popped again, but she sounded great for the hour or so she was playing for! :( I need a more permanent solution for stepping the voltage down!
Click to expand...

Now that you're basically finished you might be interested in the thread that discusses power transformer temperature, cooling fans and bucking transformers:

http://www.audiokarma.org/forums/showthread.php?t=294444

It sounds to me like you could free up your variac and plug your 222C into its own bucking transformer.
 
Hi,
Do you guy's think I should make one of these to lower the voltage on my Scott
LK48 as well, Right now I have it plugged in to a Tripp lite Line Stabilizer the Spec
are,

Input 87-127 Volts
output: Within ANSI-C84-1 Voltage Limits
With a Maximum Load of 600 Watts

What do you guy's think

Tube
 
Blast said:
:dunno: I'm using Sovtek 5AR4's in two Scott 222C's (and a 299A) with no problems whatsoever...

Ask yourself, "What would Herman do?"
Click to expand...

I was happy with a Sovtek in a Heathkit AA-100 completely rebuilt... until a few days ago when it began to hum. Testing the 5AR4, one half is totally dead...

Time to chase for some NOS ones in my case.

BTW, the Sovtek lived for two years.
 
tube-a-lou said:
Hi,
Do you guy's think I should make one of these to lower the voltage on my Scott
LK48 as well, Right now I have it plugged in to a Tripp lite Line Stabilizer the Spec
are,

Input 87-127 Volts
output: Within ANSI-C84-1 Voltage Limits
With a Maximum Load of 600 Watts

What do you guy's think

Tube
Click to expand...

That sounds like it just might stabilize the wall voltage without lowering it. After I was done my B+ sits at 438V, a little higher than the 420V specified, but that's at 117V input. If I were to run it at my wall voltage of 125V, the B+ would be at 468V--which I think it way too high! The VARIAC is clunky right now so I'm building a bucking traffo into a box that'll just sit behind my rack. Cooler amp, happier tubes, and no mess.

gugusse said:
I was happy with a Sovtek in a Heathkit AA-100 completely rebuilt... until a few days ago when it began to hum. Testing the 5AR4, one half is totally dead...

Time to chase for some NOS ones in my case.

BTW, the Sovtek lived for two years.
Click to expand...

Yea, I nabbed a 'MESA ENGINEERING' tube, which turns out to be a Sovtek for something like $17. I plan to grab an older US rectifier sometime in the future just in case :thmbsp:
 
Last edited:
thefragger said:
That sounds like it just might stabilize the wall voltage without lowering it. After I was done my B+ sits at 438V, a little higher than the 420V specified, but that's at 117V input. If I were to run it at my wall voltage of 125V, the B+ would be at 468V--which I think it way too high! The VARIAC is clunky right now so I'm building a bucking traffo into a box that'll just sit behind my rack. Cooler amp, happier tubes, and no mess.



Yea, I nabbed a 'MESA ENGINEERING' tube, which turns out to be a Sovtek for something like $17. I plan to grab an older US rectifier sometime in the future just in case :thmbsp:
Click to expand...

Where in the power supply are you getting 438V? At the rectifier or the center tap of the output transformers? At the restifier the Schematic I have shows 430V.
 
NOSValves said:
Where in the power supply are you getting 438V? At the rectifier or the center tap of the output transformers? At the restifier the Schematic I have shows 430V.
Click to expand...

At the output transformer's C/T, relative to ground.

I assumed that because the 430V isn't used by anything (other than the resistor that steps it down) that the 420V is the B+. Here's what my schematic says;

420VB.jpg
 
Let's say I want to replace all the resistors for the fun of it--is there a way to tell the wattage of the old resistors based on their size? I've been digging around for a little bit but cannot find any concise reference for this vintage.

I'm hoping to replace all the carbon comps with metal film to help the little bit of (constant, independent of volume) white noise I can hear with my ear next to the woofer.
 
thefragger said:
Let's say I want to replace all the resistors for the fun of it--is there a way to tell the wattage of the old resistors based on their size? I've been digging around for a little bit but cannot find any concise reference for this vintage.

I'm hoping to replace all the carbon comps with metal film to help the little bit of (constant, independent of volume) white noise I can hear with my ear next to the woofer.
Click to expand...
Did you check the schematic? They often have notes where it tells you - look for something like: "All resistors are ½ Watt unless otherwise specified"
 
Tinkerbelle said:
Did you check the schematic? They often have notes where it tells you - look for something like: "All resistors are ½ Watt unless otherwise specified"
Click to expand...

Yea, I can't find that on any of the 222A, B, C, or D versions, nor the 299 or LK48 schematics that I have. :no:
 
Tinkerbelle said:
Did you check the schematic? They often have notes where it tells you - look for something like: "All resistors are ½ Watt unless otherwise specified"
Click to expand...

The SAMS Photofact I have for the 222B just says:

Resistors: all wattages 1/2 watt, or less, unless otherwise specified.

Do you have a SAMS for your 222C ?
 
Last edited:
mikey99 said:
The SAMS Photofact I have for the 222B just says:

Resistors: all wattages 1/2 watt, or less, unless otherwise specified.

Do you have a SAMS for your 222C ?
Click to expand...

Excellent! I thought it might've been 1/2W parts. Thank you for that!!

Unfortunately, I do not have the SAMS for my 222C, they sound like useful documents! :sigh:
 
mikey99 said:
Another thing I noticed , that article about rebuilding the Scott 222C
has a parts list, including resistors, about 2/3 of the way down.
I'm not sure if this represents the original parts values or an upgraded parts
list used for the rebuild.

http://www.audioxpress.com/magsdirx/ax/addenda/media/hansen2644.pdf

EDIT: Hmm, apparently the values are different, based on the modifications the author made to the circuit.
Click to expand...

Yea, they didn't rebuilt the 'correct' circuit in that article, which I was bummed out to read AFTER I printed it out in its entirety.

They also use 1/4W parts, it seems.
 
Last edited:
You must log in or register to reply here.
Back
Top Bottom