Wadia 8 VRDS Sony KSS-151A Laser parameters

[zabrzeski]

Good Day


I got a Wadia 8 with old laser and a new spare laser KSS-151A
It seems the new laser needs some voltage adjustment - if i build it in it works worse then old laser.

Does somebody got a Wadia schematic? Where are the meassuring points? What voltage should be adjust for the Wadia?



Regards Christopher

 

[Mike P]

I'm not familiar with your Wadia player but on Sony machines with the KSS-151A there is usually the facility to adjust:

Focus bias
EF balance
Focus gain
Tracking gain

If I was fitting a new laser in a Sony I would check all of the above.

The laser power adjustment should generally not be touched.

 

[zabrzeski]

Good Day
Thanks for reply.

But how to adjust it - dont want to "overclock" the laser (that the laser will get demaged much quicker) You dont have any schematic?

 

[Mooly]

Using a laser power meter is the official method.

You should be able to make a good judgement call by looking at the RF on a suitable scope. You can also infer the laser current by monitoring the volt drop across the low value resistor that will be present in laser drive transistor circuit and calculating the current using ohms law. Compare the value to that printed on the pickup (last 3 digits of serial number, for example 593 would be 59.3 milliamps)

Unless you are well versed in CD theory and operation you could well end up causing damage. The laser power should not need altering when replacing a pickup.

 

[percival007]

Can you take pictures of the PCB where any adjustment pots may be?
Also of the chip-set used so we can work out what should be happening.

I doubt there'll be a Manual available to anyone other than Wadia ASC's.

P

 

[zabrzeski]

Yes it will be done today.
Will make a photo description of that what was not ok in the Wadia and what was done .It will make a clearer view of this problem

 

[zabrzeski]

 

[canvas]

Do not touch these pots if you don't have tools or knowledge to tune them. Basically, you need a SONY yeds-18 disc, DMM and an analog oscilloscope to do these adjustment. KSS-151A is very expensive. If it plays, it should be fine.

 

[zabrzeski]

CD

I took it from local service yesterday. The Wadia does not play good. I have to make more observation but it looks like this. I start play a like new original CD , it goes for incens track 3 then its for incens skip again to 3 track to the beginnig and in the speakers i hear scratching sound like You would be a DJ and moves the turntable plate.After souch sounds it skips few seconds or go back to the begining.
WAdia runs over a DAC. I asume the DAC get wrong reading from the CD and thats the sound

What was done by the service. The plate high that press the cd has been align and the motor axis was corrected couse it was not straight ( previous owner demaged the wadia )

What is strange - a new laser does not play (almost not play ) at this potentiometer positions (i or the service did not move them since we dont have a service manual for the teac or wadia.

 

[Mooly]

Unless you have a good oscilloscope and can firstly look at the RF (eyepattern) signal from the pickup then I'm afraid you have little realistic chance of fixing this.

Looking at the RF (its quality, clarity, amplitude, jitter and so on) would tell you much.