Hello,
I'm having some trouble with a quad 66 cd player. It reads instantly and sounds very nice but when it has been on for while there's a slight crackle on the right channel. It had a lot of dry solder joints so I started there (including the smd caps on the dac) and cleaned the lens but the problem was still there. I had another TDA1451A in stock so I swapped it thinking that, as it affected only one channel, it had to be the dac. The problem is still there and I probably should have done this before but I used the coax digital output on an external dac and the problem is present as well (still just on one channel). Any thoughts as to what this might be ?
Thank you!
PS : I noticed that both channels are separated inside the SAA7220 and than mixed again to be sent to the dac and the digital output, could that chip be faulty and cause this ?
I'm having some trouble with a quad 66 cd player. It reads instantly and sounds very nice but when it has been on for while there's a slight crackle on the right channel. It had a lot of dry solder joints so I started there (including the smd caps on the dac) and cleaned the lens but the problem was still there. I had another TDA1451A in stock so I swapped it thinking that, as it affected only one channel, it had to be the dac. The problem is still there and I probably should have done this before but I used the coax digital output on an external dac and the problem is present as well (still just on one channel). Any thoughts as to what this might be ?
Thank you!
PS : I noticed that both channels are separated inside the SAA7220 and than mixed again to be sent to the dac and the digital output, could that chip be faulty and cause this ?
It's not the saa7220, I swapped it with a known working one from a philips player and it still does the same. I doesn't always happen, sometimes if I stop the disc and start it again it's gone and if I repeat the process it comes back. It doesn't seem to appear during a cd but is either there or not when I start playing it.
I feel like I'm talking to myself but it might help seeing things better to write it down. When gently tapping the transport, instead of the usual skipping the crackle intensifies and also appears on the other channel, it almost sounds like it's not correcting the missing bits (it crackles more with a more damaged cd and less with a perfectly clean one).
These things are always hard to diagnose at a distance. First thing I would do is look at the RF on a scope and make sure the amplitude and general Q or quality is good. A marginal signal level can cause audible noise/distortion as the error correction encounters non correctable data. You have to do this to eliminate it as a cause.
Hi Mooly,
Thank you for the suggestion, I started with that and it was nice clean stable and had the correct amplitude, I actually followed your advice on another thread for a marantz cd11le with something similar and replaced the dram chip (mn4264P-15) that I salvaged from another player. This seems to have solved the problem, but I'll have to continue testing to be sure as it didn't always occur.
Thank you for the suggestion, I started with that and it was nice clean stable and had the correct amplitude, I actually followed your advice on another thread for a marantz cd11le with something similar and replaced the dram chip (mn4264P-15) that I salvaged from another player. This seems to have solved the problem, but I'll have to continue testing to be sure as it didn't always occur.
: then.
How can the DRAM chip only affect one channel - I thought it was still a single channel on multiplexed info at this point? Keep us updated please 🙂
That's what I thought as well and why I started by replacing the dac and the SAA7220. I don't really know how it only affected one channel (it extended to both channels when causing more errors by gently tapping the transport). Anyway replacing the dram seems to have fixed it, also I can now pretty much bang the case, turn it upside down or on its side and it'll keep reading without as much as a little skip.