Marantz SR5200 amp damaged center channel + DAC issues

[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.

[Chris56000]

Hi!

I've had a quick look and there's no direct drop–in replacement that springs to mind'

There are still reasonable supplies of the CS4228A on eBay from UK and other sellers tho' – it's highly likely that's what's causing the faults on the one I've just bought!

Chris Williams

[mzacharias]

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?

I've had very good luck with UTSource. Takes a couple weeks or even more but never had a counterfeit.

https://www.utsource.net/

[poot36]

Thanks for the link, I will have a look.

[martinho1974]

I have the same problem in my sr 5200 marantz. Was it fixed with the exchange of the cs4392?

[poot36]

@martinho1974 I have not yet ordered the replacement DACs.  A quick test to see if your DAC is bad is try inputting a digital signal into the unit and if it does not detect it cs4391 could be bad.  If you remove it you will only lose the front right and left channels but the surround channels will still work I would think.

@mzacharias When you ordered off UTSource did you get the components from them or one of the cheaper alternatives they listed?

[martinho1974]

I already changed cs4228 and it did not work, it actually got worse. Only in direct source, it recognizes the channels  passed more than 5 minutes, has sound but with noise similar to the sound of a helicopter. my doubt now is, will the substitution of 4391 will solve everything, or the 4228a having been ordered from china, very cheap, is false?

[poot36]

If the sound is bad in direct mode you have way more problems then just the DACs (as direct mode disables all digital functions of the amp).  If not I would go back to the original DAC and try replacing the cs4391.  Do you have a scope to check the clocks and digital inputs to the DACs?