Electronics > Repair

Vintage CD player repair : Philips CD 371 AKA Radiola CD 1371

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Vince:
Hello world,

Among the 20 old cheap broken CD players I bought the other day.. is this little thing. I bought it for 10 Euros, a Radiola CD1371. Looked like a cheap random player to me, but bought it just because somehow I found it cute, and wanted to diversify my experience, and also it had an uncommon fault : seller said it was working/playing CD's fine, but the display was not displaying anything, never. So works, but going blind...

Then when I popped the hood, was surprises to see a swing arm in it, a CDM 4/11, along with a TDA 1541A DAC !

That's when Gyro told me that this little thing was actually nothing less than an old Philips CD 371, pure and simple, simply wearing a "Radiola" badge... because, I learned soon after, Radiola was actually a brand owned by Philips. So makes sense. This old Philips is worth a  lot more than the 10 Euros I paid for it.. even found one on Ebay for 500 USD / 400 Euros, yikes !  :o 

Could really do with some cash at the moment but... I am not going to sell it for a profit. I am now very fond of this thing, especially know I know it's a technically interesting player. So, am keeping it for sure !  :-+

So... ater testing, here is what I found :

1) Display does not work indeed, completely kaput.  Gyro already told me it was a common problem on this player. The couple 7 segments LED displays, are driven by decoder which sports a serial interface to the CPU on the main board. Decoder goes south but the displays are fine. IIRC, Gyro said the faulty decoder chip can be replaced by an off the shelf decoder that's still available today ? Is that right ? 

2) Unlike what the seller said, the player won't read CD's. Seller is surprised, said it was working fine "last time" he tested it... now "last time" can be ages ago I guess... but regardless of how long that may be, I guess at least we can assume that if the pickup was good "last time".. it should still be good now, since it has seen no use/wear at all during that period of rest.  The guy really was very decent, I will give him the benefit of the doubt, at least until proven otherwise, of course...

So for now, we will consider that the problem could be due to

A) The storage period causing trouble : electrolytic caps gone bad ?

B) Physical damage during the transport.


Here is what happens. Initial conditions : no CD present, tray closed, player at rest, and CD clamp/top part removed so I can see what the pickup is doing.
Then I press the PLAY button and here is the sequence of events that that I witness, i chronological order

1) Something strange from the get go : the tray motor runs for one second, in the direction where it wants to close the tray, which is already closed.....
2) Laser turns on
3) Spindle turns for one second or so, a CD revolution or so, while the focus servo goes up and down full range, once. Trying to focus then, I assume...
4) Spindle stops for a split second
5) Spindle turns again for one second or so, while the focus servo goes up and down full range, once... I guess performing a second attempt at focusing.
6) This fails so spindle stop, and laser is turned off.

Then if I press PLAY again, the whole sequence is carried out again.
In the video below, I press PLAY a few times. A disc is present so you can't see the pickup, and the disc does not stop when spindle is de-energized, due to the inertia of the CD of course, but if you pay attention you can see the CD slow down a little bit then speed up again when the player does its second attempt at focusing.





You can also hear that the CD is rubbing a bit.. don't know where it comes from.. the clamping arm I guess ? Not sure it would be enough to cause the player no to read the disc ? I mean the disc looks like it's turning quite effortlessly no ?...
Still, would be cool if it didn't rub at all of course, but I don't know what I can do to fix that, in practice...


Should I try to fix this before the fixing the display, or the other way around ?

I have a Toshiba with a CDM 4/11 transport too, so I guess plug and play.. could swap transports to at least be 100% certain the problem comes from this, rather than some problem on the main board.

So here we go... let's try to save this cute little Philips shall we....

Gyro:
Yay, the impatient little bugger gets his wish at last!  ;D

I'd investigate the power rails first. The failure mode of the LED display is usually to lose the odd segment, not blank, which makes me suspect an issue with the +5V rail.

The disc seems to be starting and stopping fine. You occasionally get a scraping sound from the disc clamp if the white nylon cage catches the edge of the clamp disc. Nothing serious, it just needs a little grease. If the clamp is badly worn then it can cause the transport to vibrate, but I don't see / hear that. It's a good idea to lubricate the hinge points and clamp with a little plastic grease.

It might be worth a gentle clean of the lens too (at least this one has one!).


P.S. The case looks in pristine condition, always a good sign (the PCB too).

Gyro:
Another thought. That Axial 47uF electrolytic (2546) located underneath the transport is notorious for failure, causing laser power stability issues. I would replace that immediately (as you have the transport out). A radial part is fine as long as you lay it flat.

This could easily cause initial focus lock issues. Never attempt to change the laser adjustment without replacing this capacitor first.


P.S. You can quickly replace the electrolytic without removing the PCB, just snip the existing leads at the body and tack on a radial one. Just don't apply heat for long enough to loosen the PCB solder joints.

shakalnokturn:
Yep Gyro knows his classics!

To me it sounded like a slipping sound in your video, I'd check that the clamping is correct. I can't remember for sure but no doubt Gyro will chime in, I think there is a metal ball pivot between the white plastic and the black clamping disc.
Maybe check that isn't lost or seized in old grease.

Other than that usual checks... Swing arm swings freely, state of flex at the back plastic clamp on the lower right of the transport.

Gyro:
Haha, thanks shakalnokturn.  :D

Yes, there is a metal ball on the top of the black disc clamp shaft which bears on the underside of the main sprung flap. The white nylon bit is there to hold and centre the disc clamp when it is released and when it is dropping down onto the spindle hub and CD. If the two pivot points between the white nylon carrier and the main flap are a bit tight, it won't sit level and will slightly rub on the disc clamp. Everything just unclips.

Earlier transports used a slightly rounded blunt plastic end instead of a metal ball. These tended to wear badly and cause the whole transport to shake.


EDIT: Just reading back to the first post - Don't swap in the Toshiba transport at this stage, best to break one at a time. :)

Another Edit (I miss a lot of questions):

--- Quote ---1) Display does not work indeed, completely kaput.  Gyro already told me it was a common problem on this player. The couple 7 segments LED displays, are driven by decoder which sports a serial interface to the CPU on the main board. Decoder goes south but the displays are fine. IIRC, Gyro said the faulty decoder chip can be replaced by an off the shelf decoder that's still available today ? Is that right ? 
--- End quote ---

The shift register/decoder is built into the display. It is easy to replace with a decode chip and standard common anode LED display though. The decoder is a (NS/Microchip MM5450 / ST M5450).

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