Sony CDP-990 very low right channel output

[gnexus]

I don't see an AK CD forum. So I suppose CD player threads go here...

Background for this post:
Those here who have read my Nakamichi threads should know that all of my audio components were in non-climate storage for 20 years. Very bad idea!

Basically ALL those components now are unfortunately damaged in one way or another. Flooding of 4 feet of water during hurricane Harvey did not help the situation. Fortunately most things were ok. But the audio components did not fare well due to excessive heat and humidity.

The CDP-990 has slight top panel cosmetic damage and a bad belt. The output level pot also needed a cleaning. But otherwise it seemed fine. Until now...

The CDP-990 still sounds fantastic. But when I went to re-record a broken cassette tape I found out that the right channel (why is it ALWAYS the right channel?) is -20dB lower than the left.

Fortunately the CDP-990 seems a lot more straightforward to repair than a cassette deck! The schematic shows not much in the audio amp output section other than ICs 403/503. Those are RC5532 op amps. There's also some electrolytic caps.

I don't currently have a scope for detailed diagnostics. I haven't even checked the optical output yet as I don't have an optical cable. But most likely the digital sections are fine. Both the fixed and variable line outs have the same issue. So it's not the output pot causing the low output.

Currently, after being very depressed about having ANOTHER audio component with problems, I'm wondering if there's anything else I should check before ordering and swapping out the right channel op amp?

Thanks in advance for any comments and suggestions.

Edit:
Wow! This is a no brainer!
RC5532 op amps are currently on sale for only $3.99 for 10, with free shipping, at a very large but unnamed e-commerce site! Might as well just swap it out and see what happens!

 

[Hajidub]

I don't see an AK CD forum. So I suppose CD player threads go here...

Background for this post:
Those here who have read my Nakamichi threads should know that all of my audio components were in non-climate storage for 20 years. Very bad idea!

Basically ALL those components now are unfortunately damaged in one way or another. Flooding of 4 feet of water during hurricane Harvey did not help the situation. Fortunately most things were ok. But the audio components did not fare well due to excessive heat and humidity.

The CDP-990 has slight top panel cosmetic damage and a bad belt. The output level pot also needed a cleaning. But otherwise it seemed fine. Until now...

The CDP-990 still sounds fantastic. But when I went to re-record a broken cassette tape I found out that the right channel (why is it ALWAYS the right channel?) is -20dB lower than the left.

Fortunately the CDP-990 seems a lot more straightforward to repair than a cassette deck! The schematic shows not much in the audio amp output section other than ICs 403/503. Those are RC5532 op amps. There's also some electrolytic caps.

I don't currently have a scope for detailed diagnostics. I haven't even checked the optical output yet as I don't have an optical cable. But most likely the digital sections are fine. Both the fixed and variable line outs have the same issue. So it's not the output pot causing the low output.

Currently, after being very depressed about having ANOTHER audio component with problems, I'm wondering if there's anything else I should check before ordering and swapping out the right channel op amp?

Thanks in advance for any comments and suggestions.

Edit:
Wow! This is a no brainer!
RC5532 op amps are currently on sale for only $3.99 for 10, with free shipping, at a very large but unnamed e-commerce site! Might as well just swap it out and see what happens!

Couldn't hurt to swap them out for that price, but swapping left/right would have determined if those were the issue.

 

[gnexus]

Couldn't hurt to swap them out for that price, but swapping left/right would have determined if those were the issue.

Yeah. That was my first thought also.

But that's twice as much work if it's actually bad, which is likely. In addition, there's always the chance of solder pads lifting when replacing any ICs. So best just to swap with new if the part is readily available.

I checked the headphone output with a meter this morning. It's also -20dB low on the right channel. Both outputs go through the op amps. So it's quite likely the op amp is bad. Will check the optical out tomorrow when parts arrive to confirm the op amp.

 

[dimanag]

Hello!
IMHO if the IC was bad then it will be No or very distorted music from that channel.
I will suspect the capacitor at the input of the ic for that Chanel to be high on ESR.

 

[gnexus]

Hello!
IMHO if the IC was bad then it will be No or very distorted music from that channel.
I will suspect the capacitor at the input of the ic for that Chanel to be high on ESR.

Thanks very much for that! That possibility is exactly why I was asking here.

 

[gnexus]

I have just noticed, after now looking at the PCB, that C410/510(470uF electrolytic), which the power supply of the both op amps, are badly leaking and have probably leaked out most or all the electrolyte.

Haven't yet checked the capacitance. But it looks like both those caps are definitely bad!

 

[dimanag]

C403 and c503 47uf /50v will be of interest
C510 and c410 are for the power supply o the ic. If it looks/ measure bad you have to change them.
Are you sure it is not glue?

 

[gnexus]

These Elna "Duorex"(Durex?) caps are the NASTIEST slimy caustic pieces of crap ever seen!

Their leakage badly damaged the PCB making it nearly impossible to solder anything to it! I really hope it's just these caps because it would be nearly impossible to replace those ICs the way this board is now. You can barely see the traces and the photo of the traces in the manual is for other PCB.

Edit:
Found the correct PCB trace photo. That helps!

 

[gnexus]

The only 470uF caps I currently had were 200V. So had to adapt them to work.

Will need to order new caps... at least it still works.

I'm currently uncertain if this actually fixed the right output level. Even my headphones got screwed up in the non-climate storage and flood. I've cleaned the level pot on the headphones 3 times now and it STILL has intermittent problems...

At least the output pot on the Sony is now working good after extensive cleaning...

 

[gnexus]

Right output definitely looks better now. But it's still 5-10dB lower.

 

[gnexus]

C403 and c503 47uf /50v will be of interest
C510 and c410 are for the power supply o the ic. If it looks/ measure bad you have to change them.
Are you sure it is not glue?

C410 and c510 were badly leaking.

After replacing those caps the right volume level in my headphones was intermittently quite loud. I assumed it was the headphone connection or headphone volume pot because it seemed to change as the cable was moved. But maybe it was from the Sony? It didn't last long enough to know.

If it's now intermittent it probably wouldn't be the IC... maybe C503?

 

[gnexus]

Swapping out C503 had no effect. That cap reads 53uF. So it's within the correct tolerance.

Reinstalled the original C503 cap. No change, of course. Right channel is currently -6dB lower compared to the left.

 

[dimanag]

Can you unplug the headfone pcb? Is now the sound equal to both chanels?
I think that your phone jack may have corroded contacts . Just an ideea!

 

[gnexus]

Can you unplug the headfone pcb? Is now the sound equal to both chanels?
I think that your phone jack may have corroded contacts . Just an ideea!

That's easy enough to do!
But that idea doesn't really make sense. The headphone amp is a different IC. (No change)

Still waiting on delayed shipment of an optical cable and RC5532 op amps to test. I'm running out of other possibilities unless a resistor is bad...

But thanks for reminding me that I need to clean the volume pot on my headphones. Again...

 

[gnexus]

It's not IC503... replacing it had no effect.

There's equal output on optical digital out. So, fortunately and as assumed, it's not a problem in the digital sections.

Now I'm running out of ideas of the culprit with my very limited test equipment and audio troubleshooting experience.

Resistor somewhere maybe? But resistors very rarely go bad...

 

[dimanag]

My mistake!
Take out the vr board!
The one with the volume pot.
Check again from the fixed outputs.

 

[gnexus]

My mistake!
Take out the vr board!
The one with the volume pot.
Check again from the fixed outputs.

Been there. Done that already... That was actually the first step before even posting here.

Obviously I was going about the troubleshooting all wrong on this CD player. This was because the analog section looked very straightforward and it certainly doesn't seem to be a digital issue.

I'm now doing the troubleshooting (somewhat, since still no scope...) more professionally:

1) Made an audio test tones CD with 90 test tones, including 440Hz.

2) I used that test CD with a DMM capable of reading low level AC RMS voltages to locate where the audio signal is lower.

That allowed me to determine that IC502, an AD1860N d/a converter, has no audio output. So the incoming right input to the audio amp is only half the level of the left channel.

The P/S voltages to IC502 are all correct. The digital input from IC203 is good. But the input to IC502 is incorrect voltage. So either there's PCB trace issues at IC502 or it's bad.

There's lots of leaked electrolyte crap at the IC502 socket. So it's possible that's what's causing the issue. Either that or the electrolyte crap damaged that IC.

 

[gnexus]

Swapped IC402 with IC502. Now the right level is only 1-2 dB lower than left with 400Hz test tone.

But right channel is slightly lower still with music - maybe 3-4dB at most.

So it was mainly a PCB issue causing the low right channel.

I can live with only 1-3dB lower. But it would be nice to eliminate the cause of that, if possible.

It still also needs a new belt (backordered) and new caps...

 

[gnexus]

Gonna go ahead and also swap the left channel RC5532 with a TI NE5532. That way they'll at least be matching. The TI NE5532 also has slightly better specs.

Maybe that will also help even out the output levels?
Hopefully at least won't make them more uneven!

Edit:
No change. At least not worse!

 

[gnexus]

Still waiting on a new belt for the CD tray... but it worked okay with assistance of a finger.

In the meantime I replaced the caps with correct ones.

But now the tray won't stay closed and it never detects a CD - even though it worked fine before the new caps.