I didn't know about the 2220b service manual error, now it wont pass DBT

Discussion in 'Marantz Audio' started by JoshHendi, Jun 13, 2018 at 10:58 AM.

  1. JoshHendi

    JoshHendi vintage audio student Subscriber

    Messages:
    899
    Location:
    southeastern Washington State
    So annoying...

    I recapped a working 2220B. After the recap, fired it up and it passed DBT and passed protection. Followed the service manual to check bias and now it wont pass DBT and wont come out of protection. Research shows the SM was wrong, but too little too late for me.

    Any ideas where to start troubleshooting? I pulled the outputs and verified they are all okay, but short of that didnt get to anything else, the situation was super deflating.

    Where should I start? The problem started after attempting to measure J712/J718
     

     

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  2. Leestereo

    Leestereo Super Member

    Messages:
    2,040
    Location:
    Ottawa, ON
    With the output transistors out, does it pass DBT and does the relay engage?
     
  3. JoshHendi

    JoshHendi vintage audio student Subscriber

    Messages:
    899
    Location:
    southeastern Washington State
    I didn't try having all four out at the same time, but I did try it once with each channel's OPTs out and it wouldn't pass DBT and protection not engage (i can try all four out when I get home)
     
  4. Jailtime

    Jailtime Standin' on a corner Subscriber

    Messages:
    11,371
    Location:
    Velva ND
    That shouldn't have blown it up using the SM procedure, I think it just measures off by a bit. Are you sure you didn't short across the pins with a probe?
     
  5. JoshHendi

    JoshHendi vintage audio student Subscriber

    Messages:
    899
    Location:
    southeastern Washington State
    Okay thanks for the clarification (wasnt sure if that was the case or not)... I use mini-grabbers so pretty sure I didnt short anything, but Im setting it to the side for now since I have other projects to get to,,, Ill be back
     

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