Nakamichi CDC-4A Laser Focus Coil -10V after new power supply Caps

[markos4553]

R118= 1.006 Kohms should be 1 Kohms
R119= 5.699 Kohms should be 1 Kohms

In the above post R118 and R119 are transposed with an error in the "should be....."


R118= 5.699 Kohms should be 5.6 Kohms
R119= 1.006 Kohms should be 1 Kohms


Sorry!


Mark K.

 

[Salar]

There shouldn´t be nothing wrong with the real worls values against the thoretical values from the schematic. I guess they are o.k. As I mentioned before, are there transistors -that amplify he signal - in the singnal path to the coils?

 

[anatech]

Hi Mark,
Depending on what equipment you are using to measure capacitance and resistance, a few components seem to be out of tolerance or close to it. This is unusual these days, so you should have a second look at them. I don't think they would cause your problem, but the readings you have might point to a problem with the part. So the parts to recheck are:
R108
R110
R116
R118
C136
As for the fault you are seeing, if I had to point my finger at a chip, it would be IC101 for sure. I have had to replace them in the past, but this is a rare occurrence. I have fixed a lot of Sony based CD players in my time. I wouldn't be pointing my finger at a chip just yet. Have you cleaned the PCB carefully in the area of IC101? Leakage current could really throw things off in the servo. The last chemical to hit that board should be a no residue type cleaner.

-Chris

 

[markos4553]

Hey Chris,


Thank you for the suggestions and I will check them again. I have a Craftsman Auto ranging DMM that seems to work well but I may upgrade sooner than later.


I will have to get back to you again in a few days. Weekends are spoken for these days!


Take care,


Mark K.

 

[markos4553]

Hi Chris,


I rechecked those components completely out of circuit with my DMM and a Cheap component tester(CCT).


First measurement is with CCT and second is with DMM

R108= 116.4ohm; 117.7ohm should be 120ohm
R110= 3.578Mohm; 3.545Mohm should be 3.3Mohm
R116= 5.688Kohm; 5.62Kohm should be 5.6Kohm
R118= 5.701Kohm; 5.61Kohm should be 5.6Kohm


C136= 5.773uf 3.8ohm 4.2% Vloss; 5.71uf should be 4.7uf BP !!!! Replaced with New 4.7uf BP nichicon measuring ~5uf this seems to be normal for measuring BP caps with my methods.


With components in place and unit on voltage measurements across the component:
R108= 4.69V --- 4.69V
R110= 55.3mV --- -1.5mV
R116= -2.2mV --- -.3mV
R118= -2.1mV --- -.3mV


New C136= 2.3mV --- -.3mV

IC101 and surrounding areas cleaned carefully with 91% Isopropyl. Nothing indicating a problem there.


Thanks,

Mark K.

 

[markos4553]

While I had the board out again I took the opportunity to measure some more components for reference by lifting single legs.


R161= 4.88ohm should be 4.7ohm
R162= 4.91ohm should be 4.7ohm
R163= 46.2ohm should be 47ohm
R164= 10.24Kohm should be 10Kohm
R165= 33.1Kohm should be 33Kohm
R166= 337.6Kohm should be 330Kohm
R167= 522.7Kohm should be 510Kohm
R182= 10.24Kohm should be 10Kohm
R183= 98.94Kohm should be 100Kohm


C112= 473.8nf should be 470nf
C114= 46.8uf should be 47uf
C115= 47.1uf should be 47uf
C119= 48.1uf should be 47uf
C121= 48.33uf should be 47uf
C128= 34.4nf should be 33nf
C129= 48.64uf should be 47uf
C130= 48.37uf should be 47uf
C131= 1008pf should be 1000pf


Mark K.