ampage
Tube Amps / Music Electronics
For current discussions, please visit Music Electronics Forum. The sunn still shines online!

ampage archive

Vintage threads from the first ten years

Search for:  Mode:  

Re: More Info


 :
4/25/1999 10:51 PM
Brian
Re: More Info
Carlo:  
 
The way Doug has done it is also a common way of putting a standby switch into a circuit. it effectively cuts the entire circuit. The only problem with this setup is that it is hard on the rectifier tube when it first starts up due to a high current being pulled by the first filter cap.  
 
Brian
 
4/26/1999 12:37 AM
Doug

Is there a better way? Enlighten me please!  
Doug
 
4/25/1999 11:00 PM
Brian
Are you sure that you don't have any B+?  
 
you list AC voltages which are correct, but you don't list any DC voltages. I was under the impression that when a voltmeter is set to AC it doesn't measure DC. Maybe I am wrong.  
 
It doesn't sound like you have a shorted rectifier. Your plate voltages on the tube are quite high. The spec sheet lists the max voltage on each plate as 350. I would imagine that you are not pulling any current because these are pretty high. (unless you have the wrong transformer.)  
 
you listed your pin 8 voltage as 0v AC. is this grounded?  
 
Brian
 
4/26/1999 12:34 AM
Doug

I have B+ into but not out of rectifier. Pin 8 feeds into the circuit, swapped the line to pin 2, had 5V on p8 and 0v on p2, problem moved. Still no B+ out of rectifier. Something in the circuit is loading me down. But Halfsplitting the circuit I can't find it, also doing a point to point didn't show anything either. I have done a star ground collected related areas and brought them into 1 common chassis point attached to a bolt, all good connections. No cold solder joints anywhere. I am going to do another point to point and check all of my wires and components again. Tomorrow I am going to pick up some 1n4007, a calibrated meter, and 400mhz scope, and sig gen from work and see if that helps shed some light here.  
doug
 
4/26/1999 9:36 AM
Doug

Problem #1: Shorted the shield on one of my inputs, fixed.  
NOW: I have the following voltages on the preamp tube, p1: 10 VAC, p2: input sig, p3: 0vac, p4,5,9: 7vac htrs, p6: 10vac, p7 input sig, p8 0vac. Still no output. The 10vac goes up through the vol/tone controls, and to the control side of the tone bleeder cap.  
Doug
 
4/26/1999 10:28 AM
Carlo

What are your DC voltages?
 
4/26/1999 10:28 AM
Ben

Doug,  
 
There should be no AC at all in the B+ chain like you are measuring. Are you sure  
that you are measuring the DC voltages with your DMM set on DCV? Or are you measuring  
everything with it set on AC?  
 
Ben
 

<<First Page<PrevPage 2 of 5 Next> Last Page>>