Hello,
Ive been slowly chipping away at repairing my m1.5t carver with the help of others in this forum in another topic.
I finally got everything installed and began testing using the service manual instructions.
I am very new to testing amps so pretty sure I am doing some stuff wrong, but headroom testing seems pretty straight forward.
Mine did not. I drove that thing so hard I was almost putting a 1khz square wave though it, it never protected itself...and then I started to smell something and I killed the input.
I started to look into the headroom protection circuit and explanation and after looking at the schematic and theory of operation, I looked at the amp and found the double diodes from IC1 connected to Q5 and Q6 do not exist on my amp(s). I have two, and they both are missing them.
Was this a design change that was never captured in the service manuals? The holes are there, and the traces on the boards are there, just no diodes feeding Q5 and Q6.
Granted I dont think I will ever be driving these amps to this point under normal operation, so its maybe no big deal. I was just curious if this is a known thing to have these headroom protections seemingly disabled like this.
Thanks.
Ive been slowly chipping away at repairing my m1.5t carver with the help of others in this forum in another topic.
I finally got everything installed and began testing using the service manual instructions.
I am very new to testing amps so pretty sure I am doing some stuff wrong, but headroom testing seems pretty straight forward.
- Drive both channels to clipping,
- output should drop 3dB after 5ish seconds.
Mine did not. I drove that thing so hard I was almost putting a 1khz square wave though it, it never protected itself...and then I started to smell something and I killed the input.
I started to look into the headroom protection circuit and explanation and after looking at the schematic and theory of operation, I looked at the amp and found the double diodes from IC1 connected to Q5 and Q6 do not exist on my amp(s). I have two, and they both are missing them.
Was this a design change that was never captured in the service manuals? The holes are there, and the traces on the boards are there, just no diodes feeding Q5 and Q6.
Granted I dont think I will ever be driving these amps to this point under normal operation, so its maybe no big deal. I was just curious if this is a known thing to have these headroom protections seemingly disabled like this.
Thanks.
Very unlikely they accidentally left them out.
Someone at the mfr decided the circuit was not such a good idea.
Someone at the mfr decided the circuit was not such a good idea.
