dr*audio
Fish fingers and custard!
Is this the right channel? What voltage do you measure at the speaker terminals?
sansui g8000
- Thread starter maclvrbr
- Start date
kevzep
Its all about the Music
Its not in protection is it?
Speaker selector switch turned on?
Meter switched to DC mV?
Just stating the obvious things here as sometimes they are easily overlooked.
Thanks Kev I had a speaker switch off. Unit is not in protection bulb is dim. Left channel dc offset fluctuates between -4mv to 1.2mv. Left channel bias dialed in around 14mv, (SM) states 16mv.
right channel dc offset 0m vto 18mv fluctuating. right channel bias 0mv to -16mv using adjustments. I had hoped I could get these values somewhat stable, thanks for th ehelp guys
right channel dc offset 0m vto 18mv fluctuating. right channel bias 0mv to -16mv using adjustments. I had hoped I could get these values somewhat stable, thanks for th ehelp guys
kevzep
Its all about the Music
The DC offset will never be stable, it always floats around, just go put your thumb on the differential FET and you'll see what I mean.
Anything close to 0vDC is fine, as long as its not swinging up to 200mV or something like that.....
I think you are good to go.....
Anything close to 0vDC is fine, as long as its not swinging up to 200mV or something like that.....
I think you are good to go.....
kevzep
Its all about the Music
Turn your DMM leads around the other way......
I didn't quite understand what you meant by "wouldn't go above 0".....if you can dial in -16, all this is telling you is you have the leads hooked up the wrong way round but the bias is actually good...I don't actually worry about it because all you're measuring is the voltage drop across one of the emitter resistors...you just need the number 16.
kevzep
Its all about the Music
If you reverse the leads the voltage will be reading correct. Its not important whether it is displaying negative or positive, what is important is whether its displaying a voltage. You are in the DCmV range correct?
You should be able to dial that voltage from 0mV up to over 100mV.....NOT that you should be trying that. A voltage present over the emitter resistor is showing current flow, that is all. If the range is not going higher than 16mV then something is wrong.
KingBubba
"Too Much Stuff"
My G-8000, before I replaced the trimmers to Bournes, had one original that was backwards. I tested resistance on both before I fired up. My intent was to 0 them out before setting offset. To my surprise, one of the pots had to be turned clockwise to 0 it out. I am glad I used a meter before following the manual's instructions to set both pots all the way counter-clockwise. It could have had some bad side effects. From that point on, I always use the meter to set the pots down before offset is done on any amp.
kevzep
Its all about the Music
I was just going to say what Dr Audio said, its not still on DBT is it?
Correct, the factory trimmer is anti-clockwise to increase bias.....
dr*audio
Fish fingers and custard!
What is your adjustment range from what voltage to what voltage?
You are confusing DC offset with bias current adjustment. If you are measuring the voltage at the speaker terminals, adjust the DC offset trimmers to 0 volts.
The 16mV specification is for setting bias current. To measure that, you connect your meter probes to the test terminals located in the corners of the receiver's back panel.
These are two separate and distinct adjustments using different trimmers on the driver board. Each driver board has three trimmers. The two closest to the top are for setting DC offset. The one in the middle of the board is for setting bias current. Facing the front of the receiver, the driver board on the left is for the left channel and the driver board on the right is for the right channel.
This is pretty basic stuff. You have some of the most knowledgeable AK members helping you. At some point you need to accept your limitations and take it to a professional.
- Pete
The 16mV specification is for setting bias current. To measure that, you connect your meter probes to the test terminals located in the corners of the receiver's back panel.
These are two separate and distinct adjustments using different trimmers on the driver board. Each driver board has three trimmers. The two closest to the top are for setting DC offset. The one in the middle of the board is for setting bias current. Facing the front of the receiver, the driver board on the left is for the left channel and the driver board on the right is for the right channel.
This is pretty basic stuff. You have some of the most knowledgeable AK members helping you. At some point you need to accept your limitations and take it to a professional.
- Pete
dr*audio
Fish fingers and custard!
You are in the home stretch. The most important thing right now is not to blow the receiver up. When you do the bias adjustment do not use pencil type meter probes. You can slip with the probe and short something out, blowing the output transistors. Get some Pomona Mini-Grabber leads.
https://www.amazon.com/Pomona-3782-...coding=UTF8&psc=1&refRID=RN13HJFFVWNAPRJKK9AP
Get a red one and a black one.
https://www.amazon.com/Pomona-3782-...coding=UTF8&psc=1&refRID=RN13HJFFVWNAPRJKK9AP
Get a red one and a black one.
Hipocrates
Super Member
Fill the blanks.
Bias (terminals on the back of the receiver)
L:_____
R:_____
DC offset(speaker terminals) with no volume and no source.
L:_____
R:_____
You need to be very precise with the info that you post in order to get help, otherwise it gets frustrating for the nice people that are trying to help you.
Bias (terminals on the back of the receiver)
L:_____
R:_____
DC offset(speaker terminals) with no volume and no source.
L:_____
R:_____
You need to be very precise with the info that you post in order to get help, otherwise it gets frustrating for the nice people that are trying to help you.
If the previous posters comments are shared by those who have been helping please forgive me for the frustrations I have caused you. That is not what I have wanted here and will do what is necessary to be at peace with you. For those willing to assist
left DC offset .6 mv right DC offset.5 mv.
Left bias 15 mv, upper test point positive lead, lower test point negative lead. Right bias 0 mv is the closest I can get to a positive 16 mv, negative lead upper test point and positive lead lower test point. Right bias ranges from 0 mv fully CW on pot to a negative 92 mv fully CCW. Suggestions and thanks I hope this is clearly stated
left DC offset .6 mv right DC offset.5 mv.
Left bias 15 mv, upper test point positive lead, lower test point negative lead. Right bias 0 mv is the closest I can get to a positive 16 mv, negative lead upper test point and positive lead lower test point. Right bias ranges from 0 mv fully CW on pot to a negative 92 mv fully CCW. Suggestions and thanks I hope this is clearly stated
