Cardiopulmonary resuscitation of an Philips CD460 by short-curcuit? - diyAudio
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Old 6th November 2010, 11:09 AM   #1
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Cool Cardiopulmonary resuscitation of an Philips CD460 by short-curcuit?

Hi All,

my first post with more questions than answers ... A few weeks ago I got a rather old but quite well sounding Philips CD204 on Ebay. My selfmade CDP based on CDM-12 since is No. 2 ...

Back to topic: I'm planning to get the CD204 modified to NonOS and the normal stuff, but first wanted to do some kind of exercises. So I pulled out a stored for years CD460, which was my first CDP.

Click the image to open in full size.

Several years ago the Twin of this 460 was the base for my first self-made CDP. CDM-2/10, TDA1541 - not the badest stuff at all. I added a tube-out stage and some other stuff like string-suspension, conversion to a top-loader, and then had to sell it to my best friend, after he compared it with his Sony 779-ES. Doing some final shieldings to the Transformer I unfortunately murdered it by drilling a nice 1/8 hole in the windings , so I did a cardiac transplantation and took the heart from his Twin. That's about 12 years ago, so it's really interesting what happened to the PCB in the years lying around. I searched for the Service-Manual in my chaos and purchased two almost suitable Transformers, trying to get the 460 back to life.

Click the image to open in full size.

Before doing so I resoldered the most important points and checked the regulators without Display and CD-drive connected. Everything seemed fine. So I plugged the other stuff and what I saw was - nothing. Short twitching of the CD - that's it. Only with the fingers touching (yes, I know, CMOS, never ever do this ) the Display µC's Pins, it reacts up to full lightened Display.

Click the image to open in full size.

But no spinning CD, no reaction on any button. Dead?

I did some measurements as described in the Manual. Last point was the check of the Display-µC by cutting the I²-wires and connecting Pin 2 (Reset) of the MC6805L3P to Ground. Using my DMM including a Logic-Tester, Pin 1 (VSS) didn't went "Low". Second Death ?

Click the image to open in full size.

This morning I tried again some things for an hour or so - dead is normally dead, so what? Being a bit careless, I shortened "VSS" and "Reset" with the test prod. And now it's getting curious: The tray went in, the Display showed two blinking " - - ", the CD rotates and this sweet little a***ole started working . After some tests I switched it off and on again - still working? Ahhhhm, yes. Now it was possible to do the whole bunch of tests - everything ok.

Click the image to open in full size.



Click the image to open in full size.

So normally you can think "put this rather old stuff back to its case and get the hell out of here, stupid". No, there are still open questions:

  • Why resp. how can a µC come back to life by shortening two pins as mentioned above? Remarkable coincidence?
  • What I found out was, that one of the two parallel Caps (2052 and 2051, the blue ones below the µC) only showed 2.somewhat V, the other one full 5 V. Changing the Caps wouldn't be the badest idea though?
  • As it can be seen on the first picture, the LED and the Displays are all able to work - but they don't:

Click the image to open in full size.

Any suggestions for fixing?

Last questions: Does it look the same at your bench ?

Click the image to open in full size.

Click the image to open in full size.


There's still some stuff waiting for the pars practica:

Click the image to open in full size.

Click the image to open in full size.

Click the image to open in full size.

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Old 6th November 2010, 06:49 PM   #2
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Generally, the reset pin of a uproc wants a hi pulse, so shorting to the vcc was exactly the right simulation. Not having the schem, I would guess that one of those two notoriously awful blue axial electrolytics is part of the reset circuit, and replacing it will fix the fault permanently. You NEED to replace every single one of those type of caps in the unit if you want it to work for any length of time. Use Nichicons if you really want it to last. You will no doubt find that every cap in the unit that is already a Nichicon is still perfectly fine. I wouldn't trust those sanyo caps you have in mind as far as I could throw them, and throw them I would. As for the display, unless there is a bad solder joiint in the vicinity, it appears you simply have dead segments, with no option but to replace display unit. Or does that one photo show all segments lit? If so, must be a bad solder joint or two, since it is unlikely in the extreme that the controller would fail in that manner. Of course, may simply be those horrid blue lytics mucking it up.
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Old 7th November 2010, 08:53 PM   #3
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Hi Stephen,

thanks for your reply. New Caps and OPs have been already ordered last week (Oscon and Panasonic 105°, Nichicon seems not be that easy to get here?!), should arrive the next days.

What takes me wonder depending the display is, that on my "finger-trial" all Segments and LED lit, but in normal condition some segments fail, also two normal LED do so ("Repeat" & "Pause"). That was the reason I switched over the whole Display-Unit to it's Twin at that time, as mentioned above.

Today I started the Non-OS conversion (Philips put most of the IC like the SAA7220 already on sockets - Team-players ...) and tried to get the transformers into the plastic-chassis of the CD460. Not easy at all, but possible.

We'll see what's going on after replacing the satanically blue electronic crap .
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Old 8th November 2010, 02:31 PM   #4
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It sounds to me as though some sort of clock pulse was missing, and you kick started it with your 'tweak'.

If you can get it back into the faulty state, check for missing clock data to the micro.
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Old 11th November 2010, 01:55 PM   #5
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Hi All,

perhaps it is interesting for someone. I finished what was written in the Title of this Thread. The CD-460 is now running again, playing music for the first time after approx. 16 years.

Ok, what I did in between:

- tried to get the player in this kind of "Zombie-State" again; no chance, workes fine

- changed all Caps to Panasonics

- changed all Diodes to BUY25

Click the image to open in full size.


- added additional decoupling-Caps (220 nF Ceramics)

Click the image to open in full size.


- more capacity on electrolytic Caps (more than twice in summary)

Click the image to open in full size.


- tried different ways for NON-OS conversion; complete removing of the SAA7220 didn't work due to the need of the clock-output for the MA4804A, equiv. to SAA7210. Next step would be a new clock, but not for this CDP.

Click the image to open in full size.

Click the image to open in full size.


- removed the LM833N and tried some different OPs. BB OPA2132 seems to be my favorite.

Click the image to open in full size.


- brought the output of the two OP to the same Level.
- got the whole stuff in this plastic-grave and set down.

And now the moment we (ok, me ...) have all been waiting for: Music!

Very impressive at all. Very relaxed sounding, perhaps best to be compared with driving an SLS with 100 km/h on the Highway. You KNOW, that you have enough power to beat them all - but there's no need to (Norah Jones, Aziza Mustafa Zadeh, ...). But if you want, put the pedal to the metal and get started (Billy Cobham, Metallica, ...)! If then your wife calls you back to daily grind e.g. buying something for lunch, you can do so in either case (Pop).

After listening over the Silicium-Amp I plugged it to my Tube Pre/End. The acoustic Valhalla seems to be quite nearer now. I caught me several times nearly running to the CD460 due to some "unnormal sounds", which turned out to be until now buried informations on my well-known CDs ...

Again: Very impressive, not only for an old third-line CD-Player. Wiping the floor with my CDM-12 based and well-modded Player.
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