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Bleed circuit?

Posted: Tue 11/21/06 12:04 pm
by Gauge
I'm starting my build (finally) off of this layout.
Did I circle the bleed circuit? if there is not one in the layout, where would/could i put one and with what components?

thanks all

Posted: Tue 11/21/06 12:30 pm
by dartanion
Attachment?

If you are talking about a bleed resistor for the filter caps, you just need to put a 220K 2W across the first filter cap.

Posted: Tue 11/21/06 12:45 pm
by markh
What Darin said. Connect a 220k 2W resistor from the left to the bottom terminals of the 32uF/32uF in the layout.

Most of the layouts here don't have them, but I always add them!

--mark h

Posted: Tue 11/21/06 12:58 pm
by Gauge
so the 1.5k 5w resistor already there isn't doing the bleeding
i need to add on from the left lug to the bottom lug like the attachment

Posted: Tue 11/21/06 1:43 pm
by markh
Your drawing is correct. All the other resistors in the power supply circuits are in series with the flow of B+ current, and all have a cap connected to both ends. The added bleeder is in parallel (from B+ directly to ground).

--mark h

Posted: Tue 11/21/06 2:10 pm
by Gauge
Thanks much!
am i correct that this allows the caps to drain shorlty after shutoff
though i will of course check with a multimeter to make sure, i will not have to attach that alligator clip contraption?

Posted: Tue 11/21/06 2:55 pm
by dartanion
Yes, you are correct sir!!! Huh huh huh!!!

It may take a few seconds for them to completely drain though.

Posted: Tue 11/21/06 4:27 pm
by markh
Another quick way to discharge caps when you're working on an amp is to turn off the power while leaving the standby on (for several seconds). The idle current from the tubes before they cool down will draw down the B+ fairly quickly.

--mark h

Posted: Tue 11/21/06 4:51 pm
by Gauge
any noticable detriment to the sound to have this circuit in place

Posted: Tue 11/21/06 5:22 pm
by dartanion
Nope!

I use the standby method on some of the vintage amps that I work on. Most owners don't want the circuit altered, so you do what you gotta do.

Posted: Wed 09/12/07 9:07 pm
by pylet2000
Gauge wrote:any noticable detriment to the sound to have this circuit in place
Does this 220k bleed resistor lower the B+ at all? If a lower value was used, could it lower the B+ noticably?

I would assume there would always be a certain amount of current running across it with the amp running, does it increase the current demands of the high voltage windings?