Trying to fix a Kinergetics Research kcd40

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
I guess you can say I made the foolish attempt to replace the 8809 and 8808 IC's and then try the player out without making sure nothing else was bad or getting trouble shooting advice first.

I saved the player form the trash in the hopes of fixing it for a client. It would not spin a disc at all, it attempts to but does a sort of one, two step with the disc then nothing.

With past experience I have found that the laser is never the problem rather a bad spindle motor, bad connection on the board or a servo IC.

This player has a philips mechanism and board and philips IC's. I was able to source the TDA8808 and 8809 IC's on ebay... they look like the real thing or really good fakes, either way upon the first read with the new IC's the disc read out and spun up and played for about 5 seconds then the laser sled flipped "hard" to the end of the tray. :(

Now I'm back to the old problem... and possibly bad IC's again if they were bad in the first place. I was hoping some one might have a schematic for this player or have some idea were to find the "RF" test point and what the two adjustment pots on the board can do for me.

Any help or ideas would be greatly appreciated! (otherwise the player really is going in the trash)
 
The player is a KCD-40, I have no idea what model the philips board and mech are used in.

I found one philips 47uF 25V axial cap which read around 25uF so I swapped that out. All the other capacitors are Nichicon radial lead types.

I tried a cd again and it attempted to spin it up, this time I heard the laser sled snap over almost right away and the cd just sat there spinning lol

The first time I tried a cd with the new IC's I actually got a read out time and play time on the disc up to 5 seconds. The screen stays blank now.

Did some more probing and found a TCA0372DP2 14 pin servo amplifier opamp which appears to be driving the the laser sled coil. It looks like it took a little bit of heat on the board... could this be the real culprit or am I chasing wabbits again?

Not sure if there is a sub for this part... if pictures would help I can work on taking some.
 
Administrator
Joined 2007
Paid Member
The chip is a dual power opamp... I doubt that is the problem tbh. If the outputs are behaving normally (as in following normal opamp rules) then it will be fine.

Is there a separate servo board under the RAFOC unit ? That is where all the problem caps live in other Philips players. I'm not familiar with this one beyond pictures on the web but it looks to be based around second generation Philips era stuff judging by the mains transformer.
 
New TDA8808 IC (underside of board)

An externally hosted image should be here but it was not working when we last tested it.


New TDA8809 IC (underside of board)

An externally hosted image should be here but it was not working when we last tested it.


Full board with original Philips DAC removed.

An externally hosted image should be here but it was not working when we last tested it.


Close up of section with the TCA0372DP2 opamp and laser assembly connector. You will notice that I have all ready replaced some capacitors including the 47uF Philips axial lead one I mentioned earlier.

An externally hosted image should be here but it was not working when we last tested it.


The custom DAC board.

An externally hosted image should be here but it was not working when we last tested it.


Underside of laser assembly.

An externally hosted image should be here but it was not working when we last tested it.
 
Last edited:
Administrator
Joined 2007
Paid Member
Can I check the outputs with the scope? What should I see if the opamp is working?

I will get some pictures of the full board up.

It doesn't quite work like tbh. The opamp output could be in any one of a number of states, a static voltage, stuck at one rail or the other, or with an AC signal on it.

What it does do is follow rules regarding how it is arranged with regard to how the feedback around the opamp is configured, and what the applied input voltages are around the inputs.
 
Administrator
Joined 2007
Paid Member
A manual is pretty much essential tbh. You might get lucky trawling all the Philips models of that era because that main PCB is almost certainly from a standard player.

If you can still get it to spin up and read the TOC or play even for a second or two then that's enough to look at the RF on a scope and make a judgement call on amplitude and quality.

One of the pots will probably be laser current, the other perhaps some offset adjustment related to the servos.
 

Attachments

  • Philips.CD380.PCB.png
    Philips.CD380.PCB.png
    191.4 KB · Views: 100
*edit*
Thanks ahiukka! that is in fact the player I was looking for! A CD482 was pretty close as well but had a different DAC TDA1543 I think.

I was also looking at the data sheet for the TDA8808 to see where I should attempt to grab a signal from if I can get the player to read a disc again.

Pin9: FOCstart Pin16: FElag Pin18: LM which has the "monitor photodiode" Pin17: is LO which goes to what looks to be the CCS driving the laser diode.

I lack the knowledge behind the theory of how it all works other than the basics so this is a bit of a learning challenge for me right now.
 
Last edited:
Well I tried to measure the RF signal and got it trying to read out once and for a moment I saw something on the scope but it was so brief I wasn't able to even tune in to see what the wave form looked like.

The player seems to be doing a "read out" of the cd less frequently now. There is no pattern to the problem it seems.

I set the laser adjustment pot to 1K which is what the service manual says to start with and the "focus offset" to have the lens close to the mid way point. This indicates that this section of TCA0372 to me is working at least.

Pin 3 is the output output to the radial motor, on idle there is 1.86V present and the voltage hops around when the player tries to read a disc. This voltage have been skyrocketing when I heard the radial motor "snapping" to the limit point, I was hoping I could get a reading of the signal coming out of the opamp when it did that.

Have any more ideas Mooly? I'll see if I can get the player to read out again and put out an RF signal but it isn't looking good right now. Not sure how much more time this player is worth spending on but it is starting to look like it might be going to the grave yard.
 
Administrator
Joined 2007
Paid Member
No magic fixes I'm afraid. If it tries to read a disc then it means that electronically it is basically OK at a fundamental level.

Adjusting pots on a non working player introduces even more variables into the equation.

If you can get the RF to appear, even if its not locked on the scope, then you should be able to gauge the amplitude which is always useful. Around 1.2 volts pk/pk would be normal.
 
If I leave the player sit for a day now I can usually get it to spin up once or twice if I am lucky.

This is the best I can do for now... just looks like a bunch of noise. I had it set at 0.2V 0.5uS but I never really learned how to properly use a scope so the measurement is probably not accurate.

An externally hosted image should be here but it was not working when we last tested it.
 
Administrator
Joined 2007
Paid Member
Hard to say whether just noise or not.

If it is set to 0.2V/div then the level is really low. The 'Cal' knobs all need to be set to the 'Cal' position for the settings to be accurate. You need to set the trigger to be active on the scope channel being used (CH1).

You can get an idea of whether it is noise or not by carefully tweaking the laser power and seeing if the level alters. You've already altered this setting and so nothing lost in trying it on the scope.

Use AC coupling on the scope but before you measure again make sure you understand how to read the amplitude. If you set the coupling to DC then try measuring a 1.5V battery and check the trace moves around 8 divisions vertically (for the 0.2V/Div range. You will have to move the trace right down to bottom of the screen to fit it in.
 
Ok, I got it figured out now, I got the same sort of noise but on 0.5V and is around 0.75 p-p. Tried a couple of time settings and there was no real distinguishable difference... just noise.
You can get an idea of whether it is noise or not by carefully tweaking the laser power and seeing if the level alters. You've already altered this setting and so nothing lost in trying it on the scope.

Wish I had more time to work with to actually try tweaking with the laser power setting but I guess if I change it a bit I can tell if the level goes up or down or if I literally just have noise.

I'm still suspicious of the TCA0372 since I have seen intermittent/bad opamps do some very strange things it would be nice to know how it would affect the player is it was going bad... I do have a SOIC version on hand but would have to get an adaptor or hard wire it but I trust that you don't think that is what the real problem is so it would just be a blind assumption for me!

An odd thing I forgot to mention too is that the tray motor spins to pull the tray in as if it is not detecting the tray is closed just before the player attempts to read out a disk. I checked the functionality of the door switch and the player detects when the door is open or closed without problems. I also swapped out the switch for a good one and there was no difference.
 
The tray motor spins when I hit "play" then the spindle sort of "twitches" clockwise a bit then counterclockwise.

I did manage to get it to start playing the first track again for a couple seconds and was able to grab a much better shot this time before the player went into maximum overdrive and came to a slow hault.

An externally hosted image should be here but it was not working when we last tested it.


It seems to be pretty consistent with not working after this point, almost like something cools off or discharges allowing something to work for a brief period of time.
 
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.