Hello everyone! Hope you're doing well.
I recently bought a Philips CD303 that couldn’t read discs, and after a complete recap of all the boards, it seems to have come back from the dead.
When I first got it, the player powered on, but the disc would spin a couple of times very slowly and then stop. After replacing all the capacitors (Power Supply, Decoder, Servo, CDM0, and Side Panel boards), it now reads discs and plays them perfectly. The biggest improvement came after replacing the capacitors on the CDM0 board.
While I’m thrilled to have brought this gem back to life, there’s still one issue I’d like to share with you all in case someone has any ideas about what might be causing it.
When I turn on the player (cold), the disc starts spinning very fast for about 1-2 minutes. After this time, the disc stops, and pressing PLAY starts playback without any issues. It feels as though some component needs to "warm up."
Additionally, while playing a disc, the playback occasionally (though rarely) stops, and the disc halts. However, pressing PLAY again, playback starts again normally without further issues.
Here’s what I’ve observed:
I also own a working CD202. I suppose I could try swapping chips between the two units, but honestly, the thought of opening the CD202 drains my will to live… I hate those metal cages around the boards!
Any help or suggestions would be greatly appreciated.
I recently bought a Philips CD303 that couldn’t read discs, and after a complete recap of all the boards, it seems to have come back from the dead.
When I first got it, the player powered on, but the disc would spin a couple of times very slowly and then stop. After replacing all the capacitors (Power Supply, Decoder, Servo, CDM0, and Side Panel boards), it now reads discs and plays them perfectly. The biggest improvement came after replacing the capacitors on the CDM0 board.
While I’m thrilled to have brought this gem back to life, there’s still one issue I’d like to share with you all in case someone has any ideas about what might be causing it.
When I turn on the player (cold), the disc starts spinning very fast for about 1-2 minutes. After this time, the disc stops, and pressing PLAY starts playback without any issues. It feels as though some component needs to "warm up."
Additionally, while playing a disc, the playback occasionally (though rarely) stops, and the disc halts. However, pressing PLAY again, playback starts again normally without further issues.
Here’s what I’ve observed:
- The SAA7030 chip gets very hot, reaching almost 60°C.
- The SONY CX7934 chip (the slim chip located on the additional board of the decoder PCB) gets even hotter, reaching around 66°C.
I also own a working CD202. I suppose I could try swapping chips between the two units, but honestly, the thought of opening the CD202 drains my will to live… I hate those metal cages around the boards!
Any help or suggestions would be greatly appreciated.
Well, it seems that is not a fault of this chips (SAA7030 and CX7934) since I cooled down them using cold air, then turned the player ON again in less than 5 min, and works OK.
I'm lost... I don't know what to do. Maybe it's because of a capacitor? I changed them all (except the silver ones and the ceramics).
It would be great to know what part of the circuit can cause this issue (fast spinning for 2 mins).
I'm lost... I don't know what to do. Maybe it's because of a capacitor? I changed them all (except the silver ones and the ceramics).
It would be great to know what part of the circuit can cause this issue (fast spinning for 2 mins).
I can't readily find the datasheets for the chips you mention, but if memory serves correctly they are in the audio path. I own a CD 102 which is the narrower brother of of the 202. And I think the 303 is a newer generation.
Based on experience I could give you some guidelines.
"I recapped all the boards". I don't want to be rude, but do all those people restoring old audio equipment think audio equipment is like an antique car? Grind all valves, renew the piston rings, change the oil and cooling fluid, then we are good to start the engine? Electrolytic capacitors tend to deteriorate over time, sure. But it is a risk to unsolder that many components from a without even knowing what is defect. I have many capacitors in and out equipment from the 1980-ies which measure perfectly. When I service old audio equipment, I change what is out of spec, not everything randomly.
You only have to look for defective ICs as the very last step. When everything else fails, and even better, when through measurements and deduction you have established proof an IC is defective. Swapping out is a risk as such (bending pins, static electricity, damaging the socket) and I am not even mentioning desoldering a 28 pin DIL. ICs almost never fail, in literally 98% of the time it is something else. And the audio processing chips are far from the motor servo control anyway.
These CD players rely on getting a good signal from the CD, and then start working. Apparently there is no readable signal coming from the sensor. I would first start looking at the sensor output(s) with a scope. Then a possible error could be the laser itself. It only starts working after the laser itself or the controlling components have warmed up. The focus control servo. Does the lense move up and down all the time? IIRC this CD player has 4 light sensors to control tracking. What is their output?
This complete procedure has been extensively described in the service documentation, including scope pictures. Which was still made available for that equipment in the time. (What a blessing!). Unfortunately I am abroad until January and can't access the service manual. If you can't get access to it by that time, feel free to post a message in this thread and I will scan the relevant pages and post them.
But that is the path to follow, not randomly replacing components.
Based on experience I could give you some guidelines.
"I recapped all the boards". I don't want to be rude, but do all those people restoring old audio equipment think audio equipment is like an antique car? Grind all valves, renew the piston rings, change the oil and cooling fluid, then we are good to start the engine? Electrolytic capacitors tend to deteriorate over time, sure. But it is a risk to unsolder that many components from a without even knowing what is defect. I have many capacitors in and out equipment from the 1980-ies which measure perfectly. When I service old audio equipment, I change what is out of spec, not everything randomly.
You only have to look for defective ICs as the very last step. When everything else fails, and even better, when through measurements and deduction you have established proof an IC is defective. Swapping out is a risk as such (bending pins, static electricity, damaging the socket) and I am not even mentioning desoldering a 28 pin DIL. ICs almost never fail, in literally 98% of the time it is something else. And the audio processing chips are far from the motor servo control anyway.
These CD players rely on getting a good signal from the CD, and then start working. Apparently there is no readable signal coming from the sensor. I would first start looking at the sensor output(s) with a scope. Then a possible error could be the laser itself. It only starts working after the laser itself or the controlling components have warmed up. The focus control servo. Does the lense move up and down all the time? IIRC this CD player has 4 light sensors to control tracking. What is their output?
This complete procedure has been extensively described in the service documentation, including scope pictures. Which was still made available for that equipment in the time. (What a blessing!). Unfortunately I am abroad until January and can't access the service manual. If you can't get access to it by that time, feel free to post a message in this thread and I will scan the relevant pages and post them.
But that is the path to follow, not randomly replacing components.
Thank you for your response. I think you’re right about replacing components randomly, but as you’ve said, I’m a novice. It’s always a good time to learn, and I appreciate the lesson.
Before reading your post, I did some further investigation and noticed that by slightly moving the decoder board, the player started working perfectly, even from the first time I turned it on. This led me to suspect a cold solder joint, so I decided it would be a good idea to reflow all the solder joints.
After doing so, the symptoms of the disc spinning fast for 2 minutes have disappeared. Now the player powers on correctly and responds well to the PLAY button.
However, there’s now a new issue: it’s unable to read the TOC. Before reflowing the solder joints, it was able to read the TOC.
Now when it tries to read the TOC, the CDM0 fails and produces a distinctive sound, almost like a two-tone melody: niii niiii.
It’s probably a good idea to hook up the oscilloscope to check signals like the eye pattern.
Normal discs... Michael Jackson - BAD, and Methods Of Mayhem ^^'
Tomorrow I'll try to scope signals with my bro's oscilloscope.
Now I'm trying to do something that worked to me in similar situations: to add a small cardboard on the motor just change the distance between the disc and the lens. The machine is obviously trying to read the TOC. With different distances bewteen laser and CD, the CDM0 reacts different. Sometimes with this music niii niii and sometimes doing noises that suggest me that it's trying to read...
Before you do that, measure all the different paths of the 5volt supply and see, if any of them are lower than 5v the first couple of minutes.
Next, use the scope to se, if there´s substantial ripple on any of the 5volts, which may be falling in the first couple of minutes.
If the latter, you may have a bad smoothing capacitor on the 5v supply somewhere.
Thanks for your response. The issue about fast spinning the first 2 minutes is gone. Now the only issue is that it can't read the TOC.
No offense...... but it´s starting to look like, you´re doing more harm than good 😉
Rule of thumb........ Reverse the last thing you did,
and see if it will read the TOC then.
I finally have the oscilloscope, although it’s not a high-end model, it has allowed me to correctly view the eye pattern signals on other players.
I just connected it to the HF signal of a Philips CD460 player, and I can see a proper eye pattern signal. Using the same oscilloscope settings, I probed the CD303 and got a strange signal that is obviously not an eye pattern. It’s a signal that fluctuates in sync with the lens movements as it tries to read.
I also tried probing the HF signal directly at the demodulator chip (pin 7) and got a similar signal.
Here are some images showing the point where I measured the signal and the output I got on the oscilloscope:
Signal at RED point:
What I don’t understand is how this could be happening just from reflowing the solder joints on the servo board.
Is it completely impossible, that you created a "short", or actually created a cold joint in your efford to do the opposite ?
No... either you misunderstood me, or perhaps I didn’t explain myself clearly. My apologies for that.
What I mean is that before, the player could read the TOC, but it had an issue where it needed about 2 minutes to “warm up” while spinning the disc fast. When I noticed that moving the board caused strange behavior, I thought there might be some cold solder joints. That’s why I decided to reflow the entire board point by point.
After doing this on the servo board, I turned the player on, and miraculously, the 2-minute warm-up phase was gone. However, now it no longer reads the TOC.
Could it be that I fixed one issue but made another worse?
How is it possible that reflowing solder joints caused it to stop reading the TOC?
Could I have overheated a component?
Not likely.
But you have noticed, when moving the board around, that all the wire plugs/wire bundles are stiff, one core wires?
Not that unusual, that a wire can break inside a plug. I know..... boring test, but you might need to measure continuity in
all the plugs pin by pin to the other end of the wire, just to be sure, you didn´t make an unprovoked error. I know from
experience, how PITA it is to try and fix things end end up with a new error.
I decided recently to drag my CD-650 out of storage. Plugged it into the mains, light in display for about one second,
and then it died. It makes a slight squeeking sound from the power supply, and overloads one of the 5v to the front pcb
down to around 1.4v. It´s an on and off goto rep, but so far no luck.
Good luck with your 303 😉
Thanks for the idea. Tomorrow I’ll measure continuity.
Also, what I need to know is which signals I should measure with the oscilloscope besides HF.
Regarding the HF signal (eye pattern), I need to know the exact point on the board where I should take this measurement. I would be very grateful if someone could help me with this.
Good news! Here’s an update to bring you up to speed:
After countless attempts, I decided to start adjusting the Focus offset and Focus gain potentiometers. Tweaking the Focus offset pot didn’t achieve anything. But when I turned the Focus gain pot… the player started making strange noises, and… it began to read!
I tried to find the optimal position for the Focus gain pot, and at the point where it works best, it performs well for the first tracks of the CD. However, from the middle of the disc onwards, read errors start to occur.
Could it be a matter of adjusting Offset and Gain together?
The problem is that the procedure in the service manual is in German, and it also seems to require a special calibration board. Is it really necessary to follow the service manual instructions exactly? Or is there another technique I could use?
Thanks!!
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Again, very very good news:
The oscilloscope is old and needs some adjustment because the image looks a bit blurry, but it allows me to see the eye pattern clearly enough.
As you can see, this is the best signal I can achieve by adjusting Focus Offset and Focus Gain. I prefer not to touch the Laser Power potentiometer because I don’t want to risk damaging the lens or putting it under stress. I’m honestly quite scared of that potentiometer, haha.
Judging by the signal, do you think it can be improved? It seems to me that it's not symmetrical or very clean, but I'm not sure what other adjustments I can make to improve it further.
I'm quite happy with the result, although when changing discs I get different results. I need to fine-tune the potentiometers so that it reads all the discs correctly. It will be a bit of a complicated task, but I'm really motivated. It's almost there!!!
The oscilloscope is old and needs some adjustment because the image looks a bit blurry, but it allows me to see the eye pattern clearly enough.
As you can see, this is the best signal I can achieve by adjusting Focus Offset and Focus Gain. I prefer not to touch the Laser Power potentiometer because I don’t want to risk damaging the lens or putting it under stress. I’m honestly quite scared of that potentiometer, haha.
Judging by the signal, do you think it can be improved? It seems to me that it's not symmetrical or very clean, but I'm not sure what other adjustments I can make to improve it further.
I'm quite happy with the result, although when changing discs I get different results. I need to fine-tune the potentiometers so that it reads all the discs correctly. It will be a bit of a complicated task, but I'm really motivated. It's almost there!!!
Its hard to say if that is a problem in the RF or a problem with the scope not triggering correctly but as shown its not good at all. Make sure you are using the correct ground for the RF measurement and you should use a divider probe to minimise loading.
This shows a correctly adjusted eye pattern (not Philips but that doesn't matter here). Also make sure the scope is calibrated and determine if the amplitude is correct. This shows 1.2 volts pk/pk which is a typical value across many makes and models.
This shows a correctly adjusted eye pattern (not Philips but that doesn't matter here). Also make sure the scope is calibrated and determine if the amplitude is correct. This shows 1.2 volts pk/pk which is a typical value across many makes and models.
Thanks for your help Mooly!
I’m using the ground point just at the left of the HF signal.
The red circle is where I’m getting the HF signal (pin 1) and the ground I’m using is the pin 3.
I would assume that is the correct point given it looks like the test point to pick the RF up.
If you are sure the scope is triggering correctly... internal trigger, correct channel to trigger from, no HF reject, no trigger delay if the scope has that and you have adjusted the trigger point manually on the scope then it looks like a problem.
If you are sure the scope is triggering correctly... internal trigger, correct channel to trigger from, no HF reject, no trigger delay if the scope has that and you have adjusted the trigger point manually on the scope then it looks like a problem.