CDM9 servo/control pcb.....replacing the opamp

[tbla]

any good advice about replacing the original opamp JRC4560d on the controller pcb....?

[tubenut]

I have heard of some folks replacing this op amp and some report an improvement in sonics. I did it on my Philips CD850 (CDM4) but can not tell you that there was a difference. My gear is a lot more revealing now so I may do this one day on my Theta CDM9/pro based drive and see.
I recently fitted new lasers to both mine and a friends unit and both of us believe that besides reading CDRW again, our units sound quite a lot better with the new lasers then with the old worn ones. Scary......
The old ones did not skip as such, they just failed to read table of contents 1/10 times.


Regards
Guillaume

[tbla]

thanks for your input.....what opamp would be well suited for this position....?

[tubenut]

In those days I used to listen to different types on sockets and I probably used my favourite flavour at the time. AD712, AD847, OP275, NJM2114.
I can not make a "technical recomendation" but would steer toward a OPA2604 these days I think.

[capslock]

Hold it a second! Make sure this is not one of the op amps driving the focus or tracking coils. The servo amp is a special 1 A output current type op amp, and replacing it with an audio type will do no good.

[tubenut]

But you may be quite right. 4560 is often seen for higher current applications in audio gear like headphone outputs.

Regards
Guillaume

[tbla]

thanks for your inputs.....but the 4560d hardly qualifies for a 1A type or....?

http://www.njr.co.jp/pdf/ae/ae04053.pdf