Marantz CD63 & CD67 mods list

Put one or two ~10uF 250VAC lighting capacitors across live - neutral.
These can make thing worse..!:

http://www.acoustica.org.uk/other/filter.html - scroll down to 'Don't try this at home.' Not picking on you Simon - just pointing out that these things are incredibly context-dependant.

You could also throw some Y-rated caps across L-N and L-E.
Not more than 4.7nF please - any more risks serious shock from casework if there's any problem in your earth installation.
 
martin clark said:

These can make thing worse..!:

Sure, I'd better add that adding capicatance worked for me, in 3 houses, with varying systems. I didn't measure anything or study the technical side, nor do I know why it can work or in which contexts it may not.

Actually, I thought I'd not hear any difference with my current cheap bookshelf speakers, so I didn't even plug in my filter till recently. I was pleasantly surprised when it had the same effect again!

Simon
 
I've fitted Ray's CD63 things in the main:

- Place varistor S20K250 directly on mains pins of IEC socket or on mains terminals on PCB.
- Insert common-mode filter (Farnell 353-2331). Remove U242/243/245/246 and insert filter instead. Place two class X or Y capacitors 4,7n/250Vac across mains before and after filter.

My main is really bad, should be rock solid 238V like my former flat in town, now it's dancing from 215 to 220 with many noises ( I can tell when the washing machine is on... ).

I trust Ray for his good adivces, as my palyer sounds very good, but any backdraw of the filter?
 
Malefoda said:
I've fitted Ray's CD63 things in the main:

My main is really bad, should be rock solid 238V like my former flat in town, now it's dancing from 215 to 220 with many noises ( I can tell when the washing machine is on... ).

I trust Ray for his good adivces, as my palyer sounds very good, but any backdraw of the filter?

It probably won't be helping the sound, nor will it be ruining it.

Sadly the fluctuations can't be helped short of complaining to the electricity supplier (good luck!) or buying a mains regeneration gizmo (expensive!)...

Unless some of it is caused by faulty or inadequate wiring in your house, which seems unlikely.
 
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Problems!

So I have replaced all the caps FC on P/S, BlackGate on op-amp, replaced voltage regs with 2% units, replaced the op-amps with LM4562's, removed mute and HDAM and wired the output of the op-amp directly to new gold RCA jacks on the back. The player was working fine for months. Now all of a sudden, I start it up and put a CD in and it plays fine for a while then it starts to get staticy and the volume fades until there is no output at all. The only thing I can think of is driving the cables direct with the op-amp. Would putting a 100K from op-amp output to ground solve this?

Any other ideas? I'd like to fix this so I can sell it in working condition on eBay. My wife got me a C521BEE for Christmas that I already modded with AD627's on adapter boards!

Thanx in advance!
 
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After my last modds on the CD spinner (superregs with BG cap on the capacitance multiplier) used to power the dac analog, I have been noticing big improvements with time.

I will try more of these superegs on the digital +5v rails and will report latter.

As all my technical questions have allways been solved in this forum, I am now exposing a tottaly different question hoping you can point me in the right direction:

I am rebuilding a power amp (DENON POA 6600 A) and believe I am almost done.:hot:

However I am getting some trouble getting the the bias simetrical in the pre drivers bases.

This is a push pull amp that relies on a optical ship to set bias.

On the top pre driver I get 1.67v and the lower predriver base I get -1.79v. (These values should be +-1.7V)

On the drivers bases I get 1.04v (top) and -1.19v (bottom driver). (These should read +-1.1v)

The final stage is composed of four 2SC3856 and four A1492.

I should be able to get +-0.5v on the output transistors bases but I can only get 0.48v on the 2SC3856 bases and -0.62v on the bases of the A1492.

I have not soldered the output transistors yet so the readings are made in the drivers and pre drivers only (without output stage).

I did not solder the output transistors because I am afraid these voltage differences might provoque an oscilation and burn the outputs.

I really need some help and advise.

Best Regards

Ricardo
 
Just a little update

Hi folks..

Here's just a little update. I changed the coupling caps from el-caps (the old Silmics fitted perfectly :clown: ) to these films. MUCH better resolution now. It's really like night and day.
 

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