ZEN V4 PLEASE HELP

[fligti91]

ok so i just finished the build of a dual mono z4 using smps regulated supplies for the 50v power source. after running both channels for about 1.5 hour with nothing connected to speaker outs and rca the heatsinks stabilize at @58 c.
now my real problem starts. when speakers are connected all is well, no noise heard from ripple or other wise. BUT when rca's are connected things get crazy! weird crackle sounds and such that are obvious that something is very wrong. now when i just insert the rca so just the center pin is making contact then no crazy noises and i can hear the audio as intended except at a very low level. now i have not installed the resistor from the earth ground to the rca ground yet. could this be causing all my problems? i dont see how it could but then again im on here looking for help. im a novice for sure although i have built a zen v1 that is working awsome. please any advice will be greatly appreciated as i dont have a clue as to where to start right now.

 

[flg]

Let's see, yes it could. Could be the imfamous ground loop?
Very nice looking by the way.

 

[fligti91]

really? could the lack of having a ground from the rca jacket to earth be causing all my problems? why is it when the center pin is the only part of the rca connected i do hear some audio but at a very low level? will this also be corrected when the ground is resolved? im all ears.....

 

[fligti91]

i forgot to add when the rca is completely plugged in there is no sound out of the amplifier at all except the hidious crackles and such

 

[flg]

When the center pin is connected you have some sort of ground connection. Possibly only capacitive?
When the connector is all the way in??? Do you have a coupling (DC Blocking) capacitor in the input or the output of your source? Do you have a resistor to ground on the gate of your input FET?

 

[Rodeodave]

Nice, Nichicon and Orange Drops? Looking good.
Please clarify: You take the 'hot' signal from your source, but not the ground? In other words, are the ground of the source and the ground of the amp meeting somewhere?
What is the source? Is the source's ground connected to earth (safety) ground?
Is the amp's input ground connected to the circuit ground?
Is the circuit ground connected to the earth (safety) ground?

Too many questions, and too many Budvar...

 

[Rodeodave]

Nice, Nichicon and Orange Drops? Looking good.
Please clarify: You take the 'hot' signal from your source, but not the ground? In other words, are the ground of the source and the ground of the amp meeting somewhere?
What is the source? Is the source's ground connected to earth (safety) ground?
Is the amp's input ground connected to the circuit ground?
Is the circuit ground connected to the earth (safety) ground?

Too many questions, and too many Budvar...

 

[fligti91]

first the source ground and the amp ground are not connected in any way when i do get some sort of audio. second, the source is a b&k cs-117 preamp and is grounded through the ac line with a 3 prong plug. third, the amps rails are in no way connected to the earth unless the regulated supplies are doing that for me internally. the earth is connected to the input of the power supplies and thats it.

 

[fligti91]

lol, it got quiet here. i have found that the case of the smps's are conducting in some sort. my dvom is at work so i wont know in what way till tomorrow night. what i did do is dismount the power supplies and isolate them from the chassi then tried to plug everything in again. now the rca's can be plugged in and all is well on one channel(explain after). but still the gain of the amp is very poor. my preamp has a 9vrms out and at full crank the sound is barely above a whisper.
now one of my channels is down, no sound and the regulated supply bleeds down on power off almost instant. so ive got an excessive load somewhere on the board now. im not to concerned about that right now as i can just replace some common parts that would fail under conditions such as mine. so now my main question is why is the gain so low? any ideas why i would have to pump so much voltage to hear anything on the output?

 

[Zen Mod]

you must give us either proper schematic of wiring , including chassis safety gnd , or several decent macro pictures

 

[flg]

You have a PM

 

[fligti91]

.64volts across r1
41 volts at the source of the 3310
0 volts at the drain of the 3310
3.5 volts at the gate of q1
42 at the source of q5
3.5 at c2 and 3310

regulated switch mode power supply set at 49.9 volts

 

[fligti91]

drain of q1 exactly 27 volts

 

[fligti91]

gate of the 3310 is 41 volts and the center pin on the rca jack has 41 volts on it!

 

[Nelson Pass]

gate of the 3310 is 41 volts and the center pin on the rca jack has 41 volts on it!

Hard to achieve with a properly wired piece and no broken
parts. I think the Gate of the ZVP3310 is blown assuming that
it is wired correctly.

 

[fligti91]

mr pass you are the god of these amps and amp in general so ill take your word for it. thats the road i was starting to go down at this point. digikey package with new 3310's will be here tomorrow so ill post and let you know if that fixes it. hopefully ill get the gain from the amplifier then. then i gotta repair the other channel, shouldnt be to hard. its amazing how much im learning from all this even as simple as it is.

 

[flg]

I read somewhere once, if you spend 17 seconds with something on your mind, you will remeber it! And I know from many years of playing with this stuff, digging it out yourself is eaqually as imprinting on the brain as 17seconds. It just might take 4 hours
I have e'ed you but it looks like you got the same dope already
Let us know...

 

[fligti91]

great news everyone! the zvp3310 fixed it. i got my gain back. now to bring the other channel back to life. thank you all very much for all the input and help.
mr pass a special thanks for taking your valuable time to help me!

 

[fligti91]

ok the other channel is back up and running after some parts replaced. the v4 is ready for some tunes!

 

[flg]