I decided to start my own thread, instead of leeching off another thread, and taking it further off topic.
I currently have a Bedini 100/100, pictured below. The schematics on this thing are non-existent unfortunately, and I just finally took care of my offset issue I was previously having.
Now, the current issue I'm having is that I'm getting a slight hum from the bad channel that had the high offset. By replacing the DIFF transistors, I was able to get the offset close to zero. Unit does power.
On the side with the hum, I have a measurable ripple. Not sure if it has any relevance, but I'm thinking it might be one of the transistors. All caps check ok, but I'm not sure how far I can trust that.
I'm going to go ahead and post what I've done so far with this unit from the other thread.
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-Checked all semi-conductors
-Checked all caps
-Swapped power supply from the other channel to see if that would clear up the hum. Still a slight hum coming out of that channel.
-I checked all the Zeners, and had one reading 28v. I replaced it with a corrective 30v one. The offset then went from 142mv to 180mv. What?! (FIXED)
---------------------------------
Let me know if you guys have a better idea as to where my hum might be coming from.
I currently have a Bedini 100/100, pictured below. The schematics on this thing are non-existent unfortunately, and I just finally took care of my offset issue I was previously having.
An externally hosted image should be here but it was not working when we last tested it.
Now, the current issue I'm having is that I'm getting a slight hum from the bad channel that had the high offset. By replacing the DIFF transistors, I was able to get the offset close to zero. Unit does power.
On the side with the hum, I have a measurable ripple. Not sure if it has any relevance, but I'm thinking it might be one of the transistors. All caps check ok, but I'm not sure how far I can trust that.
I'm going to go ahead and post what I've done so far with this unit from the other thread.
---------------------------------
-Checked all semi-conductors
-Checked all caps
-Swapped power supply from the other channel to see if that would clear up the hum. Still a slight hum coming out of that channel.
-I checked all the Zeners, and had one reading 28v. I replaced it with a corrective 30v one. The offset then went from 142mv to 180mv. What?! (FIXED)
---------------------------------
Let me know if you guys have a better idea as to where my hum might be coming from.
Ok, I think I found the issue.
I have a bad transformer. Brand is an ETronics 1647, and the date it was manufactured was 3/83. Highly doubt I can find a supplier. All but one of the four transformers is checking out at 46v/45v secondary. The one is wide open. Not sure if this is going to be an easy fix without replacements readily available.
The transformer in question.
I have a bad transformer. Brand is an ETronics 1647, and the date it was manufactured was 3/83. Highly doubt I can find a supplier. All but one of the four transformers is checking out at 46v/45v secondary. The one is wide open. Not sure if this is going to be an easy fix without replacements readily available.
The transformer in question.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
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