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-   -   Magnavox FD3030/Philips cd303 static (http://www.diyaudio.com/forums/digital-source/220729-magnavox-fd3030-philips-cd303-static.html)

isitrisky 30th September 2012 05:10 PM

Magnavox FD3030/Philips cd303 LM317 wrong Values
 
Good day all,
I just recently pulled out my Maggie FD3030 out of storage only to discover static like sound coming from player when turned on. Static is present without cd in player. Once cd is inserted player plays but cracking can be heard through speakers for the first 5-6 tracks depending on play time. Not sure if its the power supply caps or dry joints, mute relay, or something completely different. It seems that once it warms up it goes away. And getting rid of it is not an option:D. Could it be the voltage regulators. Will measure them in a few days. Any ideas would help.

PlasticIsGood 2nd October 2012 11:24 PM

The player is worth saving, and the electrolytics will need replacing anyway, so you may as well start with a re-cap. While the boards are out, you should check it over for suspect solder joints or cracked pins on chips. If there are griplets, you should replace them with wire joints.

If the noise is on both channels and the machine is otherwise playing well, there aren't many possible causes, particularly as there's two DACs.

isitrisky 3rd October 2012 03:44 PM

I am going to overhaul the PSU. Just hoping its not the mute relay? But if it is I would just bypass it and just deal with the thud when turning off.

PlasticIsGood 3rd October 2012 05:53 PM

You could temporarily short out the contacts of relays with wire links and see if that makes any difference. If it cures the problem, check that the relay coils are getting the right voltage before you decide they are faulty. Don't short out a coil by mistake or you may blow up the circuit that drives it.

I don't have a manual and http://www.hifiengine.com/library/philips/cd303.shtml is offline just now. If there are polar electrolytic coupling caps in the audio stage, I would replace with bipolars, or back-to-back polars of double the value like Philips did on many models.

If I know an old player is worth saving and using, I always replace all electrolytics. They all have a purpose, and they're all too old. Fault-finding is much easier with new caps.

isitrisky 13th October 2012 06:17 PM

LM317 wrong values
 
I have replaced the PSU caps on the Magnavox fd3030, have yet to do the 22uf 25v cap, but have measured the voltage regulators attached to the heat sink. the 3rd one from the left is measuring different value. Pin 1 is measuring -12.34v instead of -17, pin2 is measuring -19.6 instead of -31, and pin 3 is also measuring 12.7 instead of -18v. Now could it be the regulator causing this or something else? Also there is no sound coming out of player when play is pressed just a loud hum.

PlasticIsGood 14th October 2012 04:02 PM

The -18V supply is for the two TDA1540. It is derived from one half of the same transformer winding that feeeds the +-12V supplies.

Check, measuring accross that whole winding, for 31VAC. Then check the half winding is about 15.5VAC with respect to the centre tap, and with respect to ground. Then that there is about -16.5VDC after the first stage of the voltage doubler, i.e. on the anode of diode 6111.

Did you replace the two 100uF caps 2106 and 2113? Are you sure they are the right way round?

isitrisky 14th October 2012 07:43 PM

Quote:

Originally Posted by PlasticIsGood (Post 3201358)
The -18V supply is for the two TDA1540. It is derived from one half of the same transformer winding that feeeds the +-12V supplies.

Check, measuring accross that whole winding, for 31VAC. Then check the half winding is about 15.5VAC with respect to the centre tap, and with respect to ground. Then that there is about -16.5VDC after the first stage of the voltage doubler, i.e. on the anode of diode 6111.

Did you replace the two 100uF caps 2106 and 2113? Are you sure they are the right way round?


Negative on the winding measure...No where near those values. Also the 20v are way off. The caps are on correctly. I have a resistor on the 2113 cap. Not sure why its there. Cd spins and plays, but no sound and tray wont open.


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