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-   -   Schematic Request: Adcom GCD-575 (http://www.diyaudio.com/forums/digital-source/130809-schematic-request-adcom-gcd-575-a.html)

Pars 3rd October 2008 09:27 PM

Schematic Request: Adcom GCD-575
 
Looking for a schematic for this CDP. Going to do some mods to my brother's and schematics would be beneficial if available.

Thanks!

Destroyer OS 15th October 2008 11:55 PM

I am looking for some as well. I can give you three modifications that make it sound MUCH better that are super easy.

Replace the two main capacitors next to the diodes (that feed it I think) and the two other large power supply ones with some panasonic FC's. I went with a bit more uf on the two feeding the dioes.

Here is the big one. Now I am not sure what value to use on the fixed outs, but the two little blue capacitors just behind the variable out, replace them with some Silver Mica .1uf's. They are tiny and fit just nice. The difference in sound will blow you away.

Pars 17th October 2008 06:14 PM

Thanks. I didn't intend on using the output stage, but I'll take a look at the PSU caps while I'm messing with it. Just out of curiosity, where do you find silver mica capacitors that big? All that I normally see are picofarad range....

Destroyer OS 19th October 2008 11:27 PM

Ops they are just 0.1uF panasonic polypropylene caps but let me tell you, they sound so amazingling transparent, they are probably just as good if not better.

Also replace the stock power cord, it is a joke, and throw at least one .1uf Panasonic film X2 cap across the main inputs for it.

Replacing any capacitors in the main power area with FC Panasonics would be a good idea. I might try by passing them with .1uf Panasonic polypropylene caps too.

I have not reviewed the digital area too much, maybe I will have some suggestions. Just in general the power coming it was a bit weak, and the stock capacitors are not that great either. I also put some rope caulk on the DAC chip. The diodes that are used seem to be some three legged creature.... I wanted to put in some MUR860s but no go.

I really want a schematic, the stuff is hard to follow, the tracings. I am sure there are excessive RC networks, resistors, and bad capacitors in the signal paths. Plus it runs on SPDIF, the digital I am sure needs some help. When I apply bypass caps to the main power caps tonight I will take a look at the digital if I can decipher anything about it.

Destroyer OS 23rd October 2008 12:20 AM

A friend said 1uf might be better, and I might try that. They are touchy though...

I am going to through some bypass .1uf on the psu caps I think, and start replacing more, well when all the stuff with paypal and things get worked out so I have not negative money again.

Destroyer OS 10th November 2008 01:51 AM

After looking over the digital I found that replacing the capacitors that feed the clock to be helpful. I think anything near the value will do, some Oscon or BG N's should be good over the crap that is in there.

The digital out has Elna's but you could put some Oscon's in for even better improvement, but in general I was impressed to find those.

There really is not a whole lot to do for the digital. I also put some dampening on the clock.


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