Marantz cc4300 opamp change

[jclin4]

As a newbie to CD player mods, I tried to replace the stock opamp with the OPA067 BP. I used the browndog single to dual adapter, and oriented the writing on both chips the same way as I saw the single JRC 2114 chip placed on the circuit board.

After soldering the pins, re-assembling the unit and plugging it into my amp, the output volume level is very low. I basically have to pump up the volume 3-4 times normal on my amp.

Any ideas where I messed up?

Thanks for any help.

 

[Mooly]

Hi, OPA067? Are you sure that is correct number. Changing opamp will not affect gain of circuit, sounds like something seriously amiss hear, you,ve not substituted a dual for a single have you.
Regards Karl

 

[jclin4]

I used OPA627 BP

Apologies, I stated the wrong chip. This is a single chip, so I used two of them and placed them into this adapter:

http://cimarrontechnology.com/index.asp?PageAction=VIEWPROD&ProdID=9

 

[Mooly]

These should work O.K. Big clue, have both channels got the same fault, is the sound distorted ? Have you a meter, if so check that pins 7 on both surface mount OpAmps connect to pin 8 of the original I/C. (This will confirm correct orientation). At a distance it's hard to say what is going on, it could even be something obscure like the wider bandwidth of the new I/C's causing instability.
Regards Karl

 

[jclin4]

Thanks for the tips. I will have a look to make sure that pins 7 on the opamps connect to pin 8 on the adapter. I looked up the schematics for the OPA627 and the adapter and this makes sense to me now: this should be the +Vs connection (whatever that is!).

BTW, both channels have the same sound level and I don't hear any distortion.

I have much to learn. My previous DIY experience is in speakerbuilding, where the electronics is on a much different scale. I think I should be using thinner solder to make the work a bit easier 🙂