resistor value

jestaudio · Post by **jestaudio** » Sat Jul 23, 2011 8:01 am

could some of you kind people take at look at the picture and give me a opinion as to the value of the resistor

diagrammatiks · Post by **diagrammatiks** » Sat Jul 23, 2011 8:46 am

5 megs.

opinion is why in the world.

jestaudio · Post by **jestaudio** » Sat Jul 23, 2011 9:09 am

i,d figured 5.1 meg and i can,t see what function it serves

statorvane · Post by **statorvane** » Sat Jul 23, 2011 9:39 am

Probably a bleeder resistor.

azatplayer · Post by **azatplayer** » Sat Jul 23, 2011 1:46 pm

green red green? or is the red actually brown?
5 2 100000, = 5.2M or if its brown 5.1M
Very high/slow for a bleeder.

da Geezer · Post by **da Geezer** » Sat Jul 23, 2011 1:56 pm

azatplayer wrote:green red green? or is the red actually brown?
5 2 100000, = 5.2M or if its brown 5.1M
Very high/slow for a bleeder.

Yes, If that value is correct (which it appears to be) you may as well not have a bleeder there (if that's the intended purpose)....I use 220k/3W as bleeders with good results.

G

VacuumVoodoo · Post by **VacuumVoodoo** » Sat Jul 23, 2011 2:22 pm

Perhaps a 5.1M resistor fell into 510k component bin by mistake and continued its journey to the board? A 5.1M bleeder makes no sense. Don't look for secret ingredient where there's none.

Firestorm · Post by **Firestorm** » Sat Jul 23, 2011 4:03 pm

It's definitely supposed to be 5M1. It goes across the additional larger filter cap that is switched in when the amp is switched from tube rectifier to solid-state. Maybe intended to suppress the switching transient.

diagrammatiks · Post by **diagrammatiks** » Sat Jul 23, 2011 4:38 pm

aha.

if it's in parallel with the bleeder already on the always on cap...and that bleeder is like 220k.

that would make senses.

T Wilcox · Post by **T Wilcox** » Sat Jul 23, 2011 5:46 pm

Which amp are we looking at here?

Todd

jestaudio · Post by **jestaudio** » Sat Jul 23, 2011 8:51 pm

T Wilcox wrote:Which amp are we looking at here?

Todd

stray cat Todd

C Moore · Post by **C Moore** » Sun Jul 24, 2011 12:58 am

http://www.webphix.com/schematic%20heav ... cat_30.pdf
This is the schem....so what is happening exactly.?
Thank You

diagrammatiks · Post by **diagrammatiks** » Sun Jul 24, 2011 1:07 am

there's got to be another bleeder missing or else there is no bleeder resistor in tube rec mode.

also..a 36Hy choke...

is that even possible...it would be the size of a house...

martin manning · Post by **martin manning** » Sun Jul 24, 2011 1:39 am

Don't know about the 5M1, but 80's Marshalls used 40H chokes.

VacuumVoodoo · Post by **VacuumVoodoo** » Sun Jul 24, 2011 6:57 am

"Bleeder" resistors, more correctly called "drain", are not really needed in PSU circuit, but nice to have, where the caps are NOT stacked, they will discharge through the rest of the circuit when you turn the amp off. Voltage equalizing resistors are necessary on stacked caps, drainage function is a freebe they provide.

The 5M1 resistor won't do its expected job the way it's drawn on the schematic.
It should be connected in series with the 100uF cap with the lower switch connected in parallel with the resistor. Switch will short it when changing over to SS rectifier. When in tube rectifier mode the 5M1 resistor will effectively isolate the cap from rest of circuit while keeping it charged.
It's analogous function to a switch parallel with a resistor in series with decoupling cap in cathode of a preamp gain stage. It prevents a switching transient.
Still, 5M1 is ridiculous, 510k would be more than sufficient for this job.

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