Marantz cd50 distorted unclear audio after mod

[MaccaAu]

I had a spare CD50, that i messed up the traces a little and repaired. Anyway, i was happy that I least got some distorted sound out of one channel.

Mind you, i had to use some old opamps that I left in the with a box of throw outs, ? could they be damaged or some issue with soldering?

Thanks Sam

[Light Dependant Resistor]

Hi Sam
Best to using some solder wick, de solder the op amps you placed in.
The technique with solder wick is to wet it with solder , then within about 3
seconds the solder wick will mop up any excess solder -in the process
clearing the holes, enabling easy removal. Using turned pin DIP adapters
you can then choose and trial different opamps with ease ,

With the player normally in front of you, orientation to place each dual op amp
back, is Pin 1 facing toward the right, that is furthest from the transport
toward the right. The small half circle on the op amp indicates Pin 1
is on the left of the op amp- sometimes indicated with a circle.

Many options for dual opamp, like LM4562, LM833, LM6172 ,
with an adapter you are free to trial. A humble TL072 available
everywhere will confirm the CD50 is otherwise working OK

With a multimeter you can also check for positive voltage at Pin 8
and negative voltage at Pin 4. that is with negative probe to the copper ground plane
Note how well these players were made with respect to grounding
on the top pcb,

Cheers / Chris

[Puffin]

I had this recently with my CD63. I was awaiting some Burson discrete op-amps and fitted some old ones I have had for years. One was ok, but the other sounded dreadful, distortion etc. Not sure what had happened to it before I put it away. I always put 8 pin DIL sockets in if I am intending to op-amp roll do you don't have to keep soldering and de-soldering.

[MaccaAu]

Hi Chris,
I found my DIP adaptors, so I can swap opamps. Only have 1 new OPA2134, which I was going to use for my phonostage in my amplifer but decided to put a LME4990860 instead.

Thanks for the solder tip, i couldve killed or damaged the old ones getting them out with heat. I remember the direction of the opamps, LME/LMs have a little indent, I noticed some smds just writting or a slash.

Jaycar, which I think is also in NZ, stock opamps, like the TL072. LM833N etc. For now I could use one new one? or would i need 2 to check?

The Test the RCAs can be ground also?

Thanks Regards
Sam


Hi Sam
Best to using some solder wick, de solder the op amps you placed in.
The technique with solder wick is to wet it with solder , then within about 3
seconds the solder wick will mop up any excess solder -in the process
clearing the holes, enabling easy removal. Using turned pin DIP adapters
you can then choose and trial different opamps with ease ,

With the player normally in front of you, orientation to place each dual op amp
back, is Pin 1 facing toward the right, that is furthest from the transport
toward the right. The small half circle on the op amp indicates Pin 1
is on the left of the op amp- sometimes indicated with a circle.

Many options for dual opamp, like LM4562, LM833, LM6172 ,
with an adapter you are free to trial. A humble TL072 available
everywhere will confirm the CD50 is otherwise working OK

With a multimeter you can also check for positive voltage at Pin 8
and negative voltage at Pin 4. that is with negative probe to the copper ground plane
Note how well these players were made with respect to grounding
on the top pcb,

Cheers / Chris


I had this recently with my CD63. I was awaiting some Burson discrete op-amps and fitted some old ones I have had for years. One was ok, but the other sounded dreadful, distortion etc. Not sure what had happened to it before I put it away. I always put 8 pin DIL sockets in if I am intending to op-amp roll do you don't have to keep soldering and de-soldering.

Hi Rob
Good news i found my dil socket adaptors, so I can swap in a new OPA2134 ( only 1) or use the LM4562 out of the board of a CD84 player which is a part machine now I have the working CD74, since you experienced the same, i hope that swapping will solve the problem :)

[Light Dependant Resistor]

Hi Sam
You will need both opamps in place, suggest 2x LM833 until you
get a more exotic pair. The LM833 is actually very good and will
surprise you just how good.

Yes you can use the RCA as a ground for testing, Remember
to have your meter set for ohms before attaching probe.
Ohms setting on your meter being very high impedance.

Cheers / Chris

[MaccaAu]

Hi Chris,
I just got some cheap TL072s with a cheap adaptor socket from Jaycar, sound - no audio but cracklling popping sound. I hope I didnt fry the TDA or something, as I was re doing the NOS, though least there is some sound i guess. I will check soldering or try to revert back to non NOS on the TDA.

LM833N in the Technics SL-P477A is awesome sounding with the slimcII 2 upgrade. I only forgot to replace the 2 bipolars - 22uf 16v, , only ES i have is 100uf 35v, which I think wouild be too much capacitance /voltage maybe.

http://theartofsound.net/forum/showthread.php?44518-techniccs-sl-pg477a-mash-cd-player-opamps-which-to-changer

Thanks
Cheers
Sam

[agk]

When doing the nos mod did you remember to add the mute link and lift pin 11 on the SAA7210?

[MaccaAu]

Hi Andrew I did add the mute link cable, but the 34 spc is very brittle and breaks, so maybe another wire. Currently I have no sound from it since the other opamps it was making a loud buzz. I might end up keeping it for parts - laser :)