troubleshooting philips cd650

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I screwed up and have broken my cd player.
I changed some caps, and removed the output caps, reclocked it and put chokes in the supply lines.
As far as I can see I made two mistakes neither of which should have damaged the player.
The tda1541 -15V rail cap was back to front, I replaced it and the tda1541.
I also forgot to turn the power supply for the clock on (its still not permanently installed) So the thing was spinning like crazy for a couple of minutes untill I realised all was not well.
After I rectified the mistakes the player seems to track fine, but there is absolutely no output. Any ideas how to trouble shoot this fault?
I have a schematic BTW and a scope.

thanks Arthur
 
Hi Guido,

hope you had a good xmas, Ive finally managed some time to get back to this little problem.

Not really, that's a +5V supply cap. So maybe it's toast.

I changed the cap and still 3V.


Use that scope to see if there is anything going on on the I2S lines towards the 7220 and towards the 1541.

Im not sure what Im looking for here, the pins 3 and 4 of saa7220 is the I2S input from what I can tell.
There is a very high frequency square wave that doesnt change with play/stop sequence.

The pins 15 and 16 on this chip have nothing.

Im picking this chip has gone and dragging the rails down, what u say?

If so, where on earth can I get one of these things?
 
Luke said:
Hi Guido,

Im not sure what Im looking for here, the pins 3 and 4 of saa7220 is the I2S input from what I can tell.

1,2,3 actually

There is a very high frequency square wave that doesnt change with play/stop sequence.

on 1 and 2 ?

The pins 15 and 16 on this chip have nothing.

bad.

Im picking this chip has gone and dragging the rails down, what u say?

If so, where on earth can I get one of these things?

Maybe, but if i had to guess it is the tda1541 pulling down the i2s out of the 7220 and also the powersupply) the 7220 still provides the system clock on pen 9 to the 7210, otherwise the i2s in would not have a signal. Or maybe it is partly broken.

Take out the i2s conntection to the dac (15,16,18) and have another look. Think there are some wires near the dac which you can take out (to pen 1,2/4,3).

If that does not help the 7220 is toast. They do breake down, one in my cd80 died. As for replacements, in this parts of the woods it is easy. cdm2/1541 players for 15 euro's everywhere...
 
Wow this is annoying!
Arne thankyou very much for the saa7220, but sadly it is toast.(alot of toast in this pig).

Guido,

Im getting confused.
Take out the i2s conntection to the dac (15,16,18) and have another look.

You mean on the saa7220 right? I thought there are only two I2S connections in saa72202 to tda1541, pins 15 and 16? What is pin 18 for? Maybe I am doing something wrong and thats why I cant see any I2S?

I changed the tda1451a with the original tda1541 which was working and still nothing.

Help please:bawling:

regards Arthur
 
Hi Arne,

very kind of you:) Ill post you some funds for postage, that seems only fair.
The disc just spins with this chip in it wont read the disc. The old chip reads the tracks fine. Im wondering if its something upstream, maybe the signal isnt getting to the saa7220? Im not sure what Im loking for on the scope. However, my engineers intuition(which has failed me from time to time) is telling me saa7220.
 
Luke said:
Wow this is annoying!
Arne thankyou very much for the saa7220, but sadly it is toast.(alot of toast in this pig).

Guido,

Im getting confused.


You mean on the saa7220 right? I thought there are only two I2S connections in saa72202 to tda1541, pins 15 and 16? What is pin 18 for? Maybe I am doing something wrong and thats why I cant see any I2S?

I changed the tda1451a with the original tda1541 which was working and still nothing.

Help please:bawling:

regards Arthur

Yes at the 7220. i2s is three lines. the player does not need a tda1541 to work. It does need the 7220 for the clock generation to the 7210 and the 7210 itself. If you take out the 1541 and put nothing in return, you leave the opamp input pens floating.
They dont like that and take down the powersupply :smash:

So take out the 1541 and connect pen 6 and 25 (outputs) to ground for a moment to connect the opamp input's to ground.

Then try to get the player working with just 7210/7220 (without sound obviously). If you have that working, check the powersupply pens of the dac for the correct voltages and put a working 1541 in there. That should fix it.
 
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