Yamaha CX-1000 DAC issue

n2oula

New Member
It's been a couple of month I randomly end up with distorted sound and unbearable squeaking after 1 or 2 hours of listening .

I thought it was my Denon DCD-1520 CD player that was getting old until the same phenomenon began happening more and more oftenly.

The problem turned out to come from my CX-1000 preamp DAC. I was able to make sure that was the problem by switching digital inputs (both coaxial and optical) and switching CD players on the same inputs (I own another Denon multiple CD player with digital output). The problem never happens on analog inputs.

The squeaking sounds begin after a quick deterioration of the sound quality followed by an almost complete fade out of the music. It sounds like some digital parasites you can hear when you have bad reception on your satellite receiver. I have to turn off and on the preamp to solve the issue. And then again, same problem after a couple of minutes of listening.

I think that the issue is more frequent when the preamp is warm.

Before thinking of opening up my CX-1000, does anybody know if there is a possibility it's something simple like a capacitor that was blown? Or is it most probably the DAC board?

Thanks!
 
It can a bit of a pain to get into the digital board, lots of screws. Do as elektronror writes, but also check any lose cabling inside.
 
Could be fun to locate, but start with the digital power supply rails as suggested above, their regulators and their capacitors. It sounds thermal. Run it with the lid off and see what happens- look for the hot bits and caps etc around them- dry joints etc. Try a source with 32kHz or 48kHz sampling and see if it still does it- it could be the PLL drifting off lock too.
 
For termal related issue, use cooling spray - turned upside down duster can is the simple choice for it.
 
Make sure your digital output from the CD player is set at 44.1khz or something that's compatible with the CX-1000, then start checking for bad solder joints since it does work to a certain extent.
 
CX-1000 dos 32kHz, 44.1kHz and 48kHz auto switch - so hard to do wrong.

Yeah but digital things are weird sometimes like how a computer can freeze up for no reason. OP could try feeding it a different bitrate and see if the issue is still the same, although I want to say it is probably something within the unit's internal digital realm.
 
Thank you all for your suggestions.

I retested the unit today, played for almost an hour with no issues at all, then had to leave home.
I think this is absolutely a thermal issue since last time the problem happened it was repeatedly doing it after an extended playing time even if I turned OFF / ON the unit.

Do you think cleaning up the contacts with a contact cleaner without doing any soldering work would be of any use?

Thanks again!
 
Thank you all for your suggestions.

I retested the unit today, played for almost an hour with no issues at all, then had to leave home.
I think this is absolutely a thermal issue since last time the problem happened it was repeatedly doing it after an extended playing time even if I turned OFF / ON the unit.

Do you think cleaning up the contacts with a contact cleaner without doing any soldering work would be of any use?

Thanks again!

It won't likely help. Thermal issues are either soldering cracks or failure of one of chips used in DAC section. In both cases soldering is required. You can use heat gun alond with cooling sparay to roughly identify area on board whre faulty component is located. Then oscilloscope will likely be needed to identify exact point of failure. Some can say that full board solder reflow is a way to go, but unless board is in poor shape to begin with, I do not recommend this.
 
And...did you finally have success?
In case, could you possibly describe the solution for your problem?

Actually, I have a similar problem, but contrary:
After using my CX-1000 for ~25 years, my digital board started to produce "distorted sound and unbearable squeaking" straight after powering up the unit for - only - about 2 minutes (and the "2 minutes" seem to be getting longer every month).

I suppose, the problem is connected to a capacitor on the digital board, very likely near the PLL of the digital input section.
Maybe, you have a good advice and already an idea, which cap; I also have the schematics...

Thank you, best regards from Berlin,
falconi98
 
I just took a look into the service manual: The problem should be connected to IC420, a Yamaha custom-I/O-chip called YM3623B, which obviously allows PLL-adjustment on pin 2. However, written part of the service manual says, that it is "non-connected", while schematic says the opposite. VCO-frequency seems to be determined by pin 3.

Did you (or the person who actually fixed the unit for you) change any capacitors or do adjustments on pin 2 or 3 of IC420? ;)

Thx for any information,
falconi98
 
Replacement/upgrade of C476 (25V 330uF) and C477 (25V 220uF) already solved my problem.
After doing that, it also makes sense to replace C468, 469, 470, 471, 472, 472 (10V 100uF) and all smaller ELNA caps on the board (25V 22uF) with brandnew electrolytic caps.

falconi98
 
It's been a couple of month I randomly end up with distorted sound and unbearable squeaking after 1 or 2 hours of listening .

I thought it was my Denon DCD-1520 CD player that was getting old until the same phenomenon began happening more and more oftenly.

The problem turned out to come from my CX-1000 preamp DAC. I was able to make sure that was the problem by switching digital inputs (both coaxial and optical) and switching CD players on the same inputs (I own another Denon multiple CD player with digital output). The problem never happens on analog inputs.

The squeaking sounds begin after a quick deterioration of the sound quality followed by an almost complete fade out of the music. It sounds like some digital parasites you can hear when you have bad reception on your satellite receiver. I have to turn off and on the preamp to solve the issue. And then again, same problem after a couple of minutes of listening.

I think that the issue is more frequent when the preamp is warm.

Before thinking of opening up my CX-1000, does anybody know if there is a possibility it's something simple like a capacitor that was blown? Or is it most probably the DAC board?

Thanks!

Both channels affected ?
 
Your problem may be caused by a dirty accessory coupler switch. I had an issue with mine on my CX-2000 (same as CX-1000 internally), cleaned the switch and the problem went away.
 
Your problem may be caused by a dirty accessory coupler switch. I had an issue with mine on my CX-2000 (same as CX-1000 internally), cleaned the switch and the problem went away.
Yes, I used to have a CX-1000 with contact issues on the coupler switch...
 
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