Vintage CD player repair : Philips CDC 486 6 disc changer.

[Vince]

Thanks for the advise... getting a cheap broken amp, didn't even think of that, will see what I can find on ebay or LBC....

Hmm, found that thing on LBC, a defective Sony F261R for 10 Euros. Says Stereo doesn't work anymore. I guess he means one of the channels failed... with some luck just a few power transistors to replace...

https://www.leboncoin.fr/image_son/1897811897.htm

[shakalnokturn]

Often as simple as refreshing plenty of solders.
The Sony TA-F261R doesn't use discrete power transistors on the output stage but a Sanyo STK hybrid module instead, it could cost a little more than a pair of transistors if the output is blown.
A bit of a gamble...

[Vince]

Boy I just pick an amp at random and you are telling me that you know what this thing is and what's in it ?!

... there is one thing I lie a lot about it : there is decent service manual available for it !!! Always amazes me to find service manuals for consumer gear, especially in the '90s when even professional test gear like Tektronix and HP started NOT including schematics any longer in their manuals. The world is upside down...

So am looking at the schematic as we speak.. yes first thing I noticed is what you just said ... oh well.

It uses precisely an STK4182Mk2. At least it's still available used for a couple Euros it seems, so not the end of the world even if it turns out it is indeed that thing that's faulty.

Only one channel is not working so the chip is not 100% dead, just one half of it... is that even a plausible scenario ?
We shall see. Anyway, it looks like there is quite a bunch of discrete components in that amp, other than the STK module per se.
So lots of room for a simpler fix    Hey let's be optimistic....
Who know, maybe the STK is fine and it's just the input signal that's not getting to the STK...

For 10 Euros (+ 10 Euros shipping) not much to lose... if it's not repairable I will just keep it for parts...

Anyway, it's all your fault, YOU suggested that I get a cheap amp to fix rather than getting a more expensive working one !    .... and now I am sold to the idea, I am excited to get my first amplifier and start work on it, whatever the outcome it should be fun trying to fix it...

[shakalnokturn]

Well... No, although I do have a lot of equipment in mind I didn't know off the top of my head. I did suspect the model may be STK based and as you mentioned output transistors and I kinda dragged you into this I thought I better check before feeling too guilty.

Well it's still 20€ arguably you may find a working one for hardly more, a real gamble would be to find a non working model that sells for a nice price once working.
Then you face the problem of having to sell one before you buy the next - or not.

It will soon be time you rename the topic...

[Vince]

Well it's still 20€ arguably you may find a working one for hardly more,

It's 20° shipped, the amp itself is only 10 Euros. Working ones I saw were more like :  "make me a serious offer "...

It will soon be time you rename the topic...

Naaaaaah, next post will be the last one  : "just got the amp, here is the link to its topic if you care " 

[Vince]

Deal done for the amp, got shipped today... 18,5 Euros all in ! Can't wait to receive it. In the meantime, let's play a little more with the CD player shall we ?

I just measured the current in the windings of the turntable motor, as you suggested. See results below.
Motor runs from the floating output of the lab power supply.

I had a home made 0.1 ohm-ish current shunt I cobbled together a while ago for some other purpose. 5 identical age old wire wound resistors, 0,47 ohm each, soldered in parallel. Enough to take some juice. Well now I think of it, was probably not very clever to probe motor windings with... a wire wound resistor. I don't know how much of a change I would get if I used a non inductive current shunt... guess I will have to do the experiment all over again !..... 

Anyway, for what it's worth here is what I get.

Motor draws about 10mA per volt. At 10V there is way too much noise and spikes to make sense of the waveform. Tried some mild averaging but it kills the signals along with the noise, so not much use sadly. So had to resort to single shot with no averaging. Lowered the voltage and noticed that from 5V or so and below, signal becomes much more "calm" and you can actually see something usable. I took the screenshot at 5V or so.

2mV per division AC coupled. About 1.5 DIV peak to peak, so about 3mV, which means 30mA.

Unless I am mistaken, we can see about 4 "periods" on the screen, so 4 windings passing by, hence a full revolution. We have a complete picture of the motor then. The 3 windings look pretty much identical in shape and amplitude eh ? So motor good enough for a few more years ?!

[Vince]

...

GRRR !!!!

Can't upload the pic of the scope screenshot showing the waveform, forum AGAIN refused to upload the pic with this weird and stupid message, as it did a the other day :

Code: [Select]

" Your attachment has failed security checks and cannot be uploaded. Please consult the forum administrator ".

This forum is starting to drive me nuts, can't even post bloody pictures any more ! 

[Vince]

At last !!! Here goes the offending picture !

Converted it from JPG to PNG file format, seems to make the forum happy !

However the file is now 4 times the size even though I reduced the resolution of the pic by 4 fold !

So it's not acceptable... just a short term work-around to get by ! This needs to be fixed properly...

[Gyro]

Looks fine.    The turntable is part of a closed loop system anyway, so it would actually need to have a dead spot to prevent it from spinning up.

[Vince]

Thanks Gyro, this lovely 30 year old player is good for a few more years of service then, great 

Just received my broken amp to go along with the CD player, played with it yesterday, just posted the topic about it there, if some kind soul knows about audio amps and could help me there.... or just want to see me suffer as I scratch my head about just every single tiny little thing...

https://www.eevblog.com/forum/repair/90s-audio-amp-repair-(need-help)-sony-f261r/msg3393546/#msg3393546

[Vince]

Just started work on fixing my second Philips CD player here, in case you guys might be willing to give me a hand... the swing arm experience taught me the basics so I have been able to start work on it my own, yesterday :

https://www.eevblog.com/forum/repair/cd-player-in-distress-philips-3-disc-carousel-changer/msg3403700/#msg3403700

[TheNewLab]

Yay Vince!

Been following, I have the same unit, found on the street. My CD changer won't rotate. Maybe I'll get around to fix it. Right now having fun playing old cassettes...

[Vince]

Found on the street ?! Lucky you... all I find in the streets is dog poop and cigarette butts.

Your issue sounds like an easy one, at least to diagnose. If it's a mechanical issue with a broken plastic part, might not be that easy to actually fix... but with a 3D printer these days, that's the kind of part one can make.

If you create a topic about it, come back here to give us the link, I am curious to see the repair 

[Vince]

Friends !  If I may steal 5 minutes of your valuable time, maybe I direct your attention to yet another CD repair, my third, over there :

https://www.eevblog.com/forum/repair/vintage-cd-player-repair-sony-cdp-c305-5-disc-carousel/msg3504280/#msg3504280

I fixed it somehow, but could use your input regarding what to do.. or not do, regarding adjusting the laser output, before I call it done and button it up.... thanks in advance !