Electronics > Repair
Marantz SR5200 amp damaged center channel + DAC issues
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poot36:
Thanks for the info.  I will do the reset if necessary.  I have found out that me previous post about the I2C bus been shorted is incorrect.  Even though it is marked SDA and SCL on the board silk screen, based on the configuration of other chips I now believe that it is a SPI bus and it was still a clock line that was getting shorted out.  It now correctly detects digital input signals but I am still getting no correct audio out of the surround DAC.  I will do some more testing now that I have the digital input working as I can now remove the tuner and analog input board to probe the digital board.  I really hope my replacement IC719 is not fake.
Chris56000:
Hi!

Does anyone mind if I join the party?

A seller was offering one of these "sold working with assorted intermittent buzzing faults!!" and at two figures I thought I'd join in as well!

Pics & repair–tales to follow when I get it!

Chris Williams
poot36:
Well I did the reset and that did not change anything.  I probed around with the scope and got what looked like reasonable readings on the DAC pins.  I do want to confirm that the FILT pin on the CS4228A chip is supposed to be around 3.6V or so.  It is not listed in the datasheet and is a internal voltage supply to the chip.  I did try my 2nd CS4228A chip as I ordered 2 of them and managed to blow it up by using flux that I thought was for electronics soldering but was actually for pipe work.  There were sparks between the pins!!! Not fun.  Is there a modern replacement chip for this DAC?
m3vuv:
base and drain??,is it a bipolar or mosfet?
poot36:
@m3vuv I think you may have responded to the wrong post or I have not made clear that I have fixed the transistor amplifier section of the amp and am now working on the digital side of it now.
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