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Marantz 2220b Dead right channel

goodshelac

goodshelac

Member
Happy belated turkey day AK! Just finished recapping the phono board, power supply board, and pre amp/tone board. As was when I started the right channel is dead on all inputs. Power supply tested at 35mv. Idle current set at 20mv. Left channel DC is 0 and I can see it move as I adjust the trim pot. Right channel is getting no DC at the test points nor the speaker out. I'm debating on recapping the power amp board since I've got the rest done already. Wondering if any of you may know where I should be looking to find this issue. I'm thinking it is on the PA board??? Output transistors? Any insight would be appreciated. Thanks!!
 
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MarantzRefrb said:
Did your right channel work before any of the work was done to it?
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No, it did not. I've gone over the work I have done so far and I don't see anything that would cause only one channel to drop. I'm currently looking at H005 and H006 on the power supply board as per the manual. Nothing looks bad there yet. I swapped the output transistors and still the same issue so I think we can rule that out. I'm getting power at idle current test points but not at the DC offset test points. Schematics are still a work in progress for me so that's tough going tracing that path.
 
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http://akdatabase.com/AKview/albums/Marantz/Marantz 2220B Service Manual.pdf

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I can only find the schematic for the 2220, does it looks pretty similar to your 2220b?:
http://akdatabase.com/AKview/albums/userpics/10007/Marantz 2220 Schematic HiRes USA.pdf
 
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Are you using headphones to troubleshoot? H701 and H702 are 2SC945 transistors, those are notorious for failure. Not sure if your 2220b is the same as the schematic above though.
 
That is a lovely printable version. Thank you! Yes it looks similar. At least on the power amp P700. On another thread I read the manual was wrong for the B, in regards to the test points for idle current. They are J714 to J716 and J715 to J717. DC offset points are correct in the manual.
MarantzRefrb said:
http://akdatabase.com/AKview/albums/Marantz/Marantz 2220B Service Manual.pdf

DnCrmfm.jpg


I can only find the schematic for the 2220, does it looks pretty similar to your 2220b?:
http://akdatabase.com/AKview/albums/userpics/10007/Marantz 2220 Schematic HiRes USA.pdf
Click to expand...
 
goodshelac said:
I just swapped the output transistors H001 and H002 with H003 and H004. Same result. Left channel is fine. Right channel is dead.
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It is unlikely that a bad cap alone is killing your right channel. If it's not a control, its much more likely that it is a transistor or diode. Assuming you are getting power to the board, you will probably have to start pulling transistors and testing each one, putting them back if they are good. Unless you have specialized equipment, there are no shortcuts to troubleshooting a dead amp. You just have to test a lot of components, starting with semiconductors, then resistors.
 
Steven Tate said:
It is unlikely that a bad cap alone is killing your right channel. If it's not a control, its much more likely that it is a transistor or diode. Assuming you are getting power to the board, you will probably have to start pulling transistors and testing each one, putting them back if they are good. Unless you have specialized equipment, there are no shortcuts to troubleshooting a dead amp. You just have to test a lot of components, starting with semiconductors, then resistors.
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Ok, makes sense. Would it be safe to assume that the faulty component lies in the power amp board ?
 
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