Mc 2505 no power

intoaudio

Active Member
Well I went to turn on the amp and heard loud buzz from speakers and the circuit breaker tripped so I rest it. Tried to power up again same thing. Unhooked everything and went inside. Found 2 SI rectifier diodes cracked.(mc pn# 070-041). The circuit breaker is also pouched. I bypassed the CB to get power and got smoke from one of the si rectifier's. shut it down. Does anyone happen to know a good replacement rectifier as I will change all 4. Could my power transformer also be pouched? I will need a new CB as well.
 
I also discovered that the c79 500uf cap has nothing hooked up to it, was this normal? it is a 2505-2 ser# AT3008. Does anyone have a schematic for this amp.
 
Original Mac # 070-041 was replaced with 070-126. Commercial #s 1N5401 replaced with 2N5402.
 
Perfect thanks, I' ve been looking at pics of the inside for the 2505 and everyone I come across has wires attached to the C79 cap usually a green and white wire coming from a resistor then 2 gr/wh wires going off to one side and a br wire grounding off on the other cap. I have no such wiring on mine.
 
There are a couple of circuit changes with this amplifier, and several service bulletins related to it. Just so you know. I have the manuals and the bulletins if you need them on PDF scans I can share.
 
Here are the pics

Notice the one cap I am referring to has no wires connected. The wires are hooked up to the resistor on the heat sinks (gr/wh) on other amps I see they are hooked up to the cap and then routed to the board.
 

Attachments

  • IMG_0439.jpg
    IMG_0439.jpg
    87.3 KB · Views: 91
  • IMG_0441.jpg
    IMG_0441.jpg
    72 KB · Views: 84
Got the rectifier diodes in, put in the resistor for the cap and all wiring. It is back up and sounding great. Thanks for the help.
 
MC2505: Could I ask where you got the circuit breaker, and also how exactly to bypass until i can find one?
Thank you in advance
 
You would best be patient with your orginal posted thread, there are always serious safety and liability issues when dealing with AC mains power and it's modifacation.

With the further information you have provided in your dedicated thread more complications have been added.
 
thanks for your help!

You would best be patient with your orginal posted thread, there are always serious safety and liability issues when dealing with AC mains power and it's modifacation.

With the further information you have provided in your dedicated thread more complications have been added.
 
Back
Top Bottom