Anyone tweaked the Onyko DX7711 integra CD-player?

[mpopovics]

Is somebody own and tweaked the Onkyo DX7711 integra CD player?
Briefly about the player itself:
The filter/receiver is SM5843AP, and the DAC is 2xSM5864AP, one for each channel, >9kg, robust mechanics.

If somebody tweaked, what you did it with it?
I just own one, and I would like to change the opamps, but I do not know, which opamp can be suitable.
The existing opamp type is NJM4565DD.
I can not found any datasheet for it, only for the 4560 model.
May I replace it with OPA627 or AD825?
I think the clock circiut can be tweaked with Kwak Clock, but let's see.
My plan also to add one or two more transformers, to have separated for servo, digital and analog sections, change the main cable, and probably some capacitor upgrade (the existing is Nichicon, if remember well).

So, if somebody have practice in it, welcome! I need help!

Thanks in advance!
Milan

[KlaasH]

Hi

I have a DX77111 as well. Until now I only have eliminated the muting trasistors and replaced the ouput cap's with some MKP stuff. I' am stiil thinking to replace the complete output section.
Three opamps in a row for the fixed output makes me . The variabale output has another opamp, another set of muting transistors and output cap and 50 cm more signal path. If interested i can post a copy of the output section.

gr Klaas

[mpopovics]

Hello!

Yeah, those opamps are not very friendly for me too.

I would be more then happy, if you can send the schematic of the output section (or if you have for whole player too)...

I did not found anywhere on the web.
The variable output was that I have used, but now I build my preamp, finally.
Thanks,
Milan

[Wombat]

The njm4565 is a Dual OP.

You can find the datasheet here:

http://www.njr.co.jp/pdf/ae/ae04055.pdf


edit: really worth a try to exchange it

Wombat

[KlaasH]

Some details of the (fixed) output stage.
Any ideas what tos skip?

greetings Klaas

[mpopovics]

Hello Klaas!

Yes, it looks, that the muting transistors can be eliminated.
About DAC: it seems to me, that the output here is balanced, and the first two opamp is for it.
The second two/three has to be modified somehow. Let me think about it a little.

As I have checked the schematics, it looks, that the PS have three sections:
1. Analogue PS, +/-15V, from same AC wiring the +12V for muting transistors supplied
2. Digital PS, separated regulators for servo driver (digital) unit and uP, separated for filter/DAC digital PS, from same AC line the mechanism control unit (motor, servo, etc.) supplied, with separated regulators.
3. PS for display unit (the display can be turned off in various steps), IR receiver, etc., there is nor regulator, only BJTs.

All together is 11 (eleven) regulators originally in the CDplayer, plus the PS for the display and driver unit!

The DACs running in balanced mode (?), one stereo DAC per channel.
But, there is too many opamps after the DACs.
Probably a totally another LPF section should be used? I do not know yet. Maybe the whole analog section can be eliminated and new installed.

JockoHomo, Everybody!
Any idea is welcome to us about this issue. What is your opinion?

BR,
Milan

[Nicke]

Hi.
I have an Onkyo DX 706 and the schematics are almost the same as you published(the DAC is SM 5863 but the analog output stage is almost the same).
I have have made the following modifications:

1.Changed all resistors to 1% metal film

2.Changed all capacitors in the filter to Philips 1% polypropylen

3.Changed power supply diodes to BYV27(perhaps schottkys are better ?)

4.Bigger caps in the PS

5.A new transformer to supply the DAC & analog stage

6.Change the voltage regulators(the digital +5V to the oversampling filter & clock circuit and the +5 to each DAC´s analog PS) to LM317

7.New decoupling capacitators (OSCON)

8.Change the electrolytic output cap to a SCR polypropylen 10uF

9.Changed the opamps(I finally settled on the AD797(made some adapterboards because it´s a single opamp),but I have tried OPA2134,2604,OP275,LM6172,AD823(that one is OK).

10. Biasing the opamps to "class A" with a 2mA constant current diode

11.Eliminating the muting transistors

The most of these modifications is not very difficult to make if you have some experience.If you do not want to spend all that money(and time) you should at least try the constant current diode trick...You will notice the difference easy...

Please let us know your results.

Nicke

[mpopovics]

Originally posted by Nicke
10. Biasing the opamps to "class A" with a 2mA constant current diode

Hi Nicke!

Could you describe more detailed, how to change it with constant current diode?
Could you can take a simple picture with schematic, focused how and where to connect, which type of diode?
Thanks in advance!
BR,
Milan

[Nicke]

Attach the the diode with the anode to to output of the opamp,
Then the cathode(the one with the ring at it´s side) to pin 4 -Voltage.I used att constant current diode called E202 found at www.elfa.se.
I think that there are others at RS-components.
I found someone called J506 from Vishay that should work.
The article number in my catalog from RS is :290-8041
I will try to borrow a digital camera and take some photos.

Perhaps someone else can be of any help ??

Nicke

[mpopovics]

Many Thanks!

Milan