Philips Magnavox FD1000 / CD100 'Humming' issue - diyAudio
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Old 5th August 2008, 07:29 AM   #1
Raddek is offline Raddek  United States
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Default Philips Magnavox FD1000 / CD100 'Humming' issue

Hello everyone. This may have been discussed before, and if so I'm sorry. I tried searching the other threads for a solution, but didn't find a solid answer.

I have a Magnavox FD1000 CD Player, and for the few years I've had it, it has played great and the sound was fantastic. But the other day, when I was demonstrating my CD Player to a friend, it was anything but perfect working. (Figures, the one time I show this CD Player to someone, it has to break on me.. heh).. I actually listened to a few CD's the day before and they all played perfectly. Here is the problem I am having:

Right from the start when turning it on, it hums really loud. It will still play a CD, and the music is heard, but there is loud humming in the background. After letting it warm up for about 15-20 minutes having it on and not playing, the hum will go away. But, once I play a CD after the warming up period, the humming will come back (is also starts humming along with the laser searching for tracks). The sound is also really crackly. The humming and crackling sound intensifies with the beats of the music.

Someone please help me with this problem, as I want to keep this CD Player. The problem may be with a bad capacitor?? If so, can someone please point me to a place with the best possible replacement components (or really good brand equivalent). Thanks
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Old 5th August 2008, 08:29 AM   #2
poynton is offline poynton  United Kingdom
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OK. A couple of questions to clarify the situation.

On initial turn on , without a cd in, does it hum ?

During track seek, does it hum ?


I think the answer is yes to both in which case the problem is in the audio stage after the dac.

The output muting is by reed relays which are usually reliable but do go faulty. These should mute the utput during search and at switch on.

The hum could be due to a dry joint on the output chps or possibly the dac.

Hope this helps.

Andy
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Old 5th August 2008, 08:31 PM   #3
Raddek is offline Raddek  United States
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"On initial turn on , without a cd in, does it hum ?" -- Yes
"During track seek, does it hum ?" -- Yes

So you are saying I could have 2 problems with this player ? (sorry to repeat, but I'm only verifying). One could be a bad relay, and the other could be a bad solder somewhere ? I will try to take a look at the boards again to see where I can do the repairs.
I do have the schematics for this player (a scanned copy). I will try to look for the relays you were talking about (although I'm not very good at reading schematics.. heh). Any idea where I could find a relay if it did happen to go bad ? Thanks for your help!
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Old 8th August 2008, 12:10 AM   #4
Raddek is offline Raddek  United States
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Alright.. from what you have told me, and what I have read in other threads, it sounds like I am having trouble with the SAA7000 Chip. BUT, mine doesn't have the specified SAA7000 chip. In its place is a chip labeled M4 300. Is there any kind of difference between the two? Is this chip I have just a 'compatible' replacement someone else did at one time? If in other threads they say the SAA7000 chip can cause problems like I am having, I am guessing also this M4 300 chip is making the same problem. I have tried taking it out, and putting it back in, but no difference. I re-soldered all of the chips, but doing so still didn't fix anything. If anyone is still curious as to what this CD Player is doing, I may post a video on youtube so you can hear what's going on. If the problem truly is the SAA700 Chip (in my case the M4 300), I may just have to buy one. I posted pictures and added a Red arrow pointing to the said chip.

If I am Wrong in thinking that this chip is the trouble maker, someone please let me know! Thanks!

Click the image to open in full size.
Click the image to open in full size.
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Old 8th August 2008, 07:40 AM   #5
poynton is offline poynton  United Kingdom
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Quote:
Originally posted by Raddek
"On initial turn on , without a cd in, does it hum ?" -- Yes
"During track seek, does it hum ?" -- Yes

So you are saying I could have 2 problems with this player ? (sorry to repeat, but I'm only verifying). One could be a bad relay, and the other could be a bad solder somewhere ? I will try to take a look at the boards again to see where I can do the repairs.
I do have the schematics for this player (a scanned copy). I will try to look for the relays you were talking about (although I'm not very good at reading schematics.. heh). Any idea where I could find a relay if it did happen to go bad ? Thanks for your help!
The muting relay should short the output at startup and during seek, so there should be no output, even hum, at these times.

The fact that it plays and produces music rules out faults in a large part of the circuitry. Hence IMO the SA7000 is unlikely to be faulty.

So start from the output, you can check the voltages around the mute circuits and the output op-amps and also for bad joints in this area. Use the 'tap test' for bad contacts.

If they are all fine, in play or standby, check the voltages around the dacs.

Have you changed the power supply caps yet? (don't go mad and replace every cap in sight - start with the psu!!)

Andy
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Old 21st October 2008, 11:41 PM   #6
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I'm having the exact same problem with hum in my CD-100.
Raddek's description match my experience.

Raddek's and my CD-100 also have the same tiny orange modification-board, which in some point in time have been added.
4 lines on the PCB, going from the SAA7010 to the large M4281 chip, have been bypassed and the wires are instead fed into this modification.
On the backside of the PCB, the original lines/wires have been scratched away.

I've tried to pull'n push everything inside.
The wires [Red-Brown-Black] you see, just to the right of the center, on the bottom of the white PCB, when I pull in these on imidiate startup of the machine, the hum sometimes differs.

I've taken a look at all the solderjoints. To my eyes they look healthy.

I'm puzzled. Gotta have this fine piece of technology fixed, but how.
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Old 24th October 2008, 05:11 PM   #7
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Default Problem almost solved !

Today I replaced all the radial caps in the PSU/mainboard with Panasonic 105C caps with corresponding values, but with at least twice the rated voltage, just in case.

On the DAC all axial and radial caps were also replaced apart form the 1u0 axial to which I didn't find a replacement cap.

Actually it didn't solve anything, but it's nice to have them replaced since they're 25 years old.

That didn't help the problem with humming noise and I actually experienced that no sound at all came through for some time.
The CD-100 couldn't even read the TOC.

I resoldered as many soldering dots as possible and the CD-100 could eventually read the TOC, but still had noise.
All of a sudden while pulling the wires around the M4281 chip and the added mini-PCB, sound came back with no flaws.
No humming no nothing just pure sound
Compared to my CD-104 and CD-207, the CD-100 delivers audiophile quality with razorsharp treble and precise details, whereas the other two somewhat is good HiFi.

I guess the problem is within the modification made by Philips.
You see, I too have this mini PCB.
Other CD-100's don't and I think you and I live in different countries.

I guess that the problem is connected to the M4281 socket, because it was when I twisted it a bit, that lovely and juicy sound came back.
I will now resolder everything directly connected to this.

As of now, the machine works again and I think the above will solve the problem permanently.

I've said it before and I'll say it again.
If you can be fond of technology, I'm deeply in love with my CD-100
Just like women. A lot to be fond of, but only a few really touches your heart

I'll report back later this evening with final results.

Thank you.
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Old 24th October 2008, 06:48 PM   #8
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As promised here's an update.

The CD-100 is now stable and functional.

Allthough the replacement caps in the PSU are quite a bit taller I managed to fit them inside.

During the last year the humming became worse so it's good to have this baby up and running again.
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Old 5th February 2009, 05:45 PM   #9
Raddek is offline Raddek  United States
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Sorry for the very late reply. I ended up changing 5 Capacitors on the power supply side and now it works great! I used Rubycon ZL caps to replace the old Philips ones. Three of them are suppose to be rated 25v, but I could only find 35v. I have not changed any other capacitors on the other boards. Before replacing these caps, a few months ago, I went around and re-soldered all of the chips but doing so didn't fix it. It sat around for months before I finally found good-enough capacitors to replace the old ones with. Now it's up and running like new from '82

Also note.. the new capacitors seemed to have fixed another problem this CD player had. I noticed every once and a while the LED's would flicker while playing. I guess this was a warning sign something really was going bad. Now it's better.
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Old 9th February 2009, 11:15 PM   #10
lasrl is offline lasrl  Netherlands
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replace C2230 en C2229 to 27pF display problem is over
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