Onkyo DX-7333 schematic/service manual

[stmarci]

Hello,

I have an old Onkyo DX-7333 which I just bought 2 weeks ago. At first it did not recognize discs at all, or was very picky when it did so I decided to change the whole laser assembly which resolved the issue, it plays fine everything.

Before that happened and I could listen to CDs and even after the laser assembly was changed every CD I listen to has a mild distortion in the analogue signal path - headphones and RCA out (SPDIF is perfectly fine).

I'm wondering if anyone has a schematic for this particular CD player, or service manual.

I'm a newbie but I would like to fix this issue. However I wouldn't want to start swapping out components one-by-one without understanding the insides at first. I couldn't find it on the Internet.

Any help is appreciated.

Best Regards,
Márton

 

[DadoOsk]

Hi stmarci,
I also own this model and I found that DX-7222 has very similar schematic.
Service manual in attachment.

 

[stmarci]

Hi DadoOsk,

Thank you so much!

 

[DadoOsk]

Hope it helps.

 

[cumbb]

I still have a friend's Onkyo DX-7333 to tune. I think I'll post the progress in this thread.
First of all: in my opinion, this Onkyo is one of the best CD players. Its sonic potential is far greater than that of expensive and most expensive ones. In addition, most of the components that can reasonably be replaced are in a lower size range, which allows the use of e.g. mica capacitors. The construction is not very complex, so that a complete re-soldering is within a feasible range. Almost everything is connected to just one SINGLE 5 VDC. This prevents audible modulations caused by different power supplies (less noise and dirt: much much cleaner). I had this many years ago. And also connected it to the amplifier's power supply unit, for example. That was final: quasi endless resolution and homogeneity;-) And its DAC (also symmetrical) allows direct connection to an amplifier. It is also usually loud enough - most here are over motorized anyway: lots of amplifiers between source and speakers;-) A lot can also be done mechanically.

So you could simply leave out its analog output at the beginning of the revision: bridge it with capacitors. Since the analog output amplifiers are no longer running, I disconnected them from the power supply. Since only a positive voltage is needed now, I will disconnect the - 12 VDC later.
And here are the photos: From the DAC directly to the RCA sockets using electrolytic capacitors (e.g. KS-C, 100 µF - 16V, they sound great) and also the ground directly from the DAC to the sockets. I removed the original feeds to the sockets (all the holes).

 

[cumbb]

I still had time to quickly omit a secondary winding (2 diodes removed) and deaden the negative voltage (negative diode of the remaining secondary winding removed). I also recommend removing the small diode-bridging capacitors for sound reasons.
I would install larger power supply capacitors later. But you can also connect the 3,300 µF of the negative voltage to the positive voltage, thus doubling its capacitance.
Since every little bit helps, I laid a wire from the transformer directly to the electrolytic capacitor (earth). This saves an undefined path and some soldering transitions.
And as always: use a minimum of solder.

 

[phofman]

And its DAC (also symmetrical) allows direct connection to an amplifier. It is also usually loud enough - most here are over motorized anyway: lots of amplifiers between source and speakers;-) A lot can also be done mechanically.

So you could simply leave out its analog output at the beginning of the revision: bridge it with capacitors.

Those opamps behind the DAC subtract the common-mode noise on the DAC symmetrical outputs, implement the low-pass filters required for complete/correct DA conversion, and provide low-impedance outputs so that subsequent cables and amp input do not affect the signal. Also the datasheet https://download.datasheets.com/pdfs/source/qd/tos/e008591.pdf mentions in the "Cautions" section specifically:

The wiring between the TC9268F/P output and the analog filter amplifier input must be made the shortest.

IIUC that's the exact opposite of the mod.

 

[cumbb]

I do audio;-) First I ask: what is audible, is it audible. Secondly, I ask: is it safe, does it endanger anything else?
Experience shows that the majority will prefer this pure DAC, and RF residues or influences on the sound are not audible (of the most?-). If anyone has a PP power amplifier with a tendency to oscillate, it might...-? But if anyone has a PP oscillator, he don't listen anyway;-)

So a little further work here. I want to get this thing off the table one day;-)
I replaced what I could with mica, the larger capacities with poly-caps. As always, the solder joints are minimal.

Basically, I would replace the capacitors of the quartz with mica. That helps quite a lot. But many devices do not have clean circuits. You can imagine what it looks like with tact when a tact takes different parallel or poorly defined paths. Beware of big expensive battleships - it's not worth the effort;-)

At one point I replaced the earth path. The original is soooo thin. Don't forget: no parallelization, so cut this PCB path.