On 3/6/24 16:57, M De Simone via Jukebox-list wrote:
I’m currently working on a V200 amplifier and can’t figure out where the current draw is coming from. I’ve isolated it to the 6.3 heater circuit but can’t find any issue with it.
The heater current should be 3.15 amps at 6.3 volts by adding the values of all of the tubes. This is fed from the selection receiver on two of the pins of the large 4-pin Jones plug, not the transformer on the amplifier itself.
The only problem is the humidity adjustment is missing the wire wound section so it’s basically not doing anything. I put 2 resistors in place as a replacement but when I fire up the amp my amp meter starts rising and I shut it down between 2 and 3 amps.
It's a hum adjustment, not humidity. It just sets the center tap ground on the heater circuit. You can leave it out in most cases. Original is 75 ohms but 100 ohms will be fine for a replacement. Should be rated for at least half a watt for a 100-ohm pot.
Usually when texting one of these amplifiers it slowly rises to about 1.5 amps and holds steady there. What am I missing here?
Where are you measuring this current? Overall for selection receiver and amplifier on the AC line?
Has the amplifier been recapped? Does the current drop substantially if you pull the 5U4? Are the output tubes redplating?