You know ho wit goes, you buy a mint, working PA-5 only to find when you receive it that there are 'issues' with it. I did not do my due diligence and purchase a mint PA-5 and CA-5 from someone on Craigslist without listening to them. Bad move. The problems are as follows:
CA-5 - sounds fine after cleaning the pots. I am missing the retainer ring for a knob so it does not 'click' into place when it is placed on the shaft.
PA-5 - here is where my issues are biggest. I was a broadcast engineer but have been out of the field for many years so I am at a bit of a loss on where to start. The amplifier sounds fine when driven with my McCormack and the CA-5 at low-levels of volume or with my iPad driven directly into the PA-5. The problems start when the volume is set over about 9AM on the CA-5 or 10AM on the McCormack and over 50% on the iPad driven directly. There is cracking, static and clipping with the sound reverting to 'thin' to muting to clipping on the RIGHT channel by way of the indicator LED. I am unsure the first step to take in diagnosing the issues. I also have a BUZZ near the power button that is not related to the physical power switch. It was initially not attached as the glue that originally held it had lost the ability to hold. I removed the front panel and after a bit of Gorilla Glue it is structurally solid. It seems the become louder (the buzz) after the amplifier is on longer and increases in level when more drive is provided to the amplifier.
I downloaded the schematics and I will look at it tonight when I put the PA-5 on the bench. I am going to start with cleaning the relay contacts (if they are not sealed) and remove a couple of input capacitors and check them on my Cricket capacitance checker. I am also going to check the FET's for issues short of removing them, although I know it is not ideal.
Any other thoughts? The buzz and clipping? Are they related? What would be the first thing to check?
Thank you in advance,
Darren
CA-5 - sounds fine after cleaning the pots. I am missing the retainer ring for a knob so it does not 'click' into place when it is placed on the shaft.
PA-5 - here is where my issues are biggest. I was a broadcast engineer but have been out of the field for many years so I am at a bit of a loss on where to start. The amplifier sounds fine when driven with my McCormack and the CA-5 at low-levels of volume or with my iPad driven directly into the PA-5. The problems start when the volume is set over about 9AM on the CA-5 or 10AM on the McCormack and over 50% on the iPad driven directly. There is cracking, static and clipping with the sound reverting to 'thin' to muting to clipping on the RIGHT channel by way of the indicator LED. I am unsure the first step to take in diagnosing the issues. I also have a BUZZ near the power button that is not related to the physical power switch. It was initially not attached as the glue that originally held it had lost the ability to hold. I removed the front panel and after a bit of Gorilla Glue it is structurally solid. It seems the become louder (the buzz) after the amplifier is on longer and increases in level when more drive is provided to the amplifier.
I downloaded the schematics and I will look at it tonight when I put the PA-5 on the bench. I am going to start with cleaning the relay contacts (if they are not sealed) and remove a couple of input capacitors and check them on my Cricket capacitance checker. I am also going to check the FET's for issues short of removing them, although I know it is not ideal.
Any other thoughts? The buzz and clipping? Are they related? What would be the first thing to check?
Thank you in advance,
Darren