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Marantz 2220b Bias Questions

Richs_Trains

Richs_Trains

Well-Known Member
Hello all,

My saga of the 2220b goes on. I posted in another thread the power amp PC from the 2220b I was trying to recap, it showed some very questionable factory connections and foils. After I installed the new caps and tried to adjust the amp, I could get everything right except the bias adjustment. The SM says it should be 20mv and I get 1 volt. I thought the board was bad enough that I purchased a replacement on ebay. I completed the recap and transplant of the power amp board with the help of AK members and again went to set the amp. Well, it is still at 1 volt, not even close to 20mv. I think this amp may have been this way when I purchased it, but being a novice, I did not check the readings before starting. I used it for about a year to power the pool speakers and then switched it for a 2218 that better matched the other equipment and figured I would recap the power and amp boards. Even at 1 volt the unit sounds just great when connected to speakers. I am not a tech, I am trying to learn from AK, so please any insight as to what is causing this and should I just let it go and use the amp the way it sits or am I risking the amp or my speakers? Thanks as always!!!! Rich
 
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Steven, Thank you so much!!!!!!! I too was freaking at the voltage. Yes, using the pins in post 38 gave me the values I was looking for. I had already closed it up and put it in the closet, but after your reply, I had to see. This is just wrong, I am as dumb as a rock when it comes to knowing what everything does, but I can follow directions, if the directions are wrong, I'm screwed! Unit sounds good, I pronounce it done!
 
Well, I wanted to pronounce it done, but I notice something while letting it run. On FM only, I get a small pop, like a cap discharging, every 2 or 3 minutes. It is very slight and I really didn't listen to the FM on this unit when I was using it , so it may have been there all along. I made no change to the FM or anything but the power supply and power amp board. All other functions seem to work just fine, I am currently playing a different tuner thru the aux on the same station and all is well. Any thoughts on this one? I can't believe how much help is on this site, Thank you again Steven for help on the previous issue.
 
Wrong again, just got a pop through the aux on the extra tuner, so I guess I did something, or the new amp board could have a problem I don't know about. The first power amp board was probably fine, since the SM had me checking the wrong pins, but I really don't want to transplant the boards again. This pop just happens at random and seemingly for no reason. Ugh.
 
I'm not really experienced at diagnosis on these things yet. I read a lot of threads and am trying to absorb some of it. I guess the questions I see most often revolve around whether the sound is coming out of one channel or both. Probably hard to tell with a pop. Might need to move balance to one channel until you hear a pop and then try the other side for a while. When you know whether it is one or both channels, that begins to focus the search on certain areas within the receiver. Hopefully some real techs will guide you with some questions.
 
I bit the bullet and swapped the original power amp board back in, it was still recapped. The board is nasty, but it seems to be working. It is just so frustrating that an error in the manual caused me 3 days of grief. Thanks Steven for the help in getting it right. Rich
 
So, I am hoping I can safely say the 2220B is up an running smooth. It has been on for about 2-3 hours and no pops and all the adjustments are in spec and it plays music. Thank you all who helped in the threads about this unit.
 
Glad you got it fixed. I just rebuilt another 2220B and they sound awesome. I had kept notes from some previous rebuilds and knew about the error in the SM. It is frustrating spending time and sometimes not knowing what to do to fix it. Thanks to the posts from members on this great site all can may be overcome.

:thumbsup:
 
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