Yamaha C2A preamp: another thread about crackling and popping

I understand and agree with your suggestion. I follow that same process on my restorations. I don't change out components like semiconductors unless they are obviously bad. The majority of problems I have encountered are solder joints (especially on connectors) and electrolytic capacitors. I will definitely start with those first. I was just looking ahead and preparing for the worst when I noticed that the transistors Adam mentioned aren't carried by my usual suppliers (Mouser, Newark and Digikey).

Thanks for the information on resistors. That was enlightening to learn.
 
Hello Sonavor
Watch inside your 2 C2A before to suspect transistors .
I have no doubt that your 2 items are sic and you will find cracked resistors inside .
The first thing to do is replacing bad capacitors (most of case the green ones ) and then all adjustment pot . Once your C2A are adjusted you will see if there is (or not) defective transistors !
What is the watt rating for the adjustment pots? Is it acceptable to use multi-turn?
 
I understand and agree with your suggestion. I follow that same process on my restorations. I don't change out components like semiconductors unless they are obviously bad. The majority of problems I have encountered are solder joints (especially on connectors) and electrolytic capacitors. I will definitely start with those first. I was just looking ahead and preparing for the worst when I noticed that the transistors Adam mentioned aren't carried by my usual suppliers (Mouser, Newark and Digikey).

Thanks for the information on resistors. That was enlightening to learn.
I bought mine from Mouser a couple months ago. They may be out of stock now. I have a couple extra, but not too many, if you find you need them. Their gain is about 40% higher than the originals.
 
After resoldering all joints and replacing all of the electrolytics (many tested poorly and were bulging out), the noise floor has dramatically improved. The bias, DC offset, and power supply voltage stay within range.
There is still intermittent "popping" coming from each channel, but not at the same time.
I'm going to use my scope to find where it is originating. Because it is intermittent, it may take some time to find.
 
Did you check out those resistors . That Patrice(clinic audio) was referring to ?
 
I visually inspected them all with a flashlight and magnifying glass. I didn't find any cracked ones, but that doesn't mean they're all good. I'm going to try to isolate the source, or close to it, tonight.
 
Hello

I'm going to use my scope to find where it is originating. Because it is intermittent, it may take some time to find.
Yes , but take a freeze spray to go faster and step by step you will create the noise more quickly

In my point of view , your trouble is coming from the long board at the front of the unit but difficult to confirm without the unit in front of me
 
I can change my order.
You have experience, and if the colder rated spray is more effective, I'll get it instead.
What brand (s) are rated -70?
 
Products depend of your location (country) but don't worried -65° will be fine !
All you have to do is a thermal chock . This will make the trouble "on" and you will not wait hours after it
 
Have you made any progress on the c2a preamp problem?
Not yet. I'm in the middle of a house move and working 12 hour days, so all fun is on hold for what I hope is only another week or two. I haven't given up on it, and will post again when I resume the project.
 
i have a c2a and the same problem arose for me.i had a tech attempt to repair but popping and crackling continued ,i use MC setting, so I purchased a Yamaha HA-1 moving coil head amp which operates through the c2a moving magnet setting and the problem disappeared completely.i can only assume that this problem with my c2a is with the MC circuitry.just a thought.
 
i have a c2a and the same problem arose for me.i had a tech attempt to repair but popping and crackling continued ,i use MC setting, so I purchased a Yamaha HA-1 moving coil head amp which operates through the c2a moving magnet setting and the problem disappeared completely.i can only assume that this problem with my c2a is with the MC circuitry.just a thought.

Noisy transistor or diode in the MC amp.
 
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