I modified my 3rd CD104 with NOS and 2 TDA1541A's
This time the decoupler caps etc are on the upper side of the
PCB. see attached photo.
(MSB=1mf)
On the saa7000 every decoupler cap (0,022mf) is parallelled with a 0,1 mf mkt cap
The data and clock lines go directly from the SAA7000
to the TDA1541A's with thick copper wires ( Including the groudline, I cut the lines on the PCB.)
In a former post I mentioned that I have replaced the output caps
with tantaliums. That was a big mistake !!
Now there are two 3.3 mf (MKT) parallel, and that differs a lot !!
(6.8 mf MKT were not available)
Again I compared this mod with a NOS mod and 2 tda 1540P.
And the difference is clear. The 2 TDA1541A sound nicer !
Is there actually somebody who has done this mod too ???
Regards to all
Onno
Onno, this is interesting. Is your CD104 still alive and kicking?
Do you have the TDA1541 in simultaneous mode (like the original TDA1540 if I am correct; and like is the favourate mode nowadays)? As far as I understand the SAA7030 makes the simultaneous mode interface, so taking it out makes me not understand.
albert; Rotjeknor
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I spent some hours today trying to fix it. I switched it on after several years, and it played. Then I decided to upgrade the elco output coupling caps. Did it. Now it refuses to read the TOC it used to read very quickly some days ago!
The tray doesn't open or close. The Open/Close button acts the motor, the belt runs but I fear some piece felt and the tray doesn't move... if I play the laser turns on and moves up/down, the motor spindle a couple of turns. Then it stops and no TOC... Since the look of the servo board I suspect it, but meanwhile I'm reading this whole thread... Merci!
Stefano
The tray doesn't open or close. The Open/Close button acts the motor, the belt runs but I fear some piece felt and the tray doesn't move... if I play the laser turns on and moves up/down, the motor spindle a couple of turns. Then it stops and no TOC... Since the look of the servo board I suspect it, but meanwhile I'm reading this whole thread... Merci!
Stefano
Finally understood what the hell the griplets are! Found a link with nice shots (sorry for the Italian). Grundig CD7550 Riparazione | GRUNDIG love
CD 104 radial arm does not move.
Hi everybody.
Even though I have read a lot of fantastic postings in this forum, I just recently became a member.
And I hope all you guys with many years of Philips CD 104 experience can help me in the right direction.
The story is, that I just bought this player cheap, hoping to fix it using all your good advices. The griplets and other solderings have been fixed.
The player acts the same before and after having done the basic treatment. When putting a CD in, it can read the TOC. But when I want to play a track, the swing arm moves from side to side, without playing anything.
Eventually I manually tried to move the swing arm in action. When I moved it, it tried to get back to another position. Eventually it does not move anymore.
Service Loop A works fine, but Service Loop B slows down the disc rotation, and eventually ends saying f.ex. "-2 0000" in the display. Sometimes "-1 0000". The swing arm does not move at all, and stays fixed in the center position. The disc keeps rotating.
The radial motor amplifier transistors BD135/136 (6241/6240) gets pretty hot. I can hardly hold my finger on it.
When I switch off the CD player, the swing arm moves half the way op and back. So it seems like the radial motor amplifier works somehow.
I have checked all the static voltages on the SERVO 2 diagram, and they all seem fine. Apart from the voltage on pin 1 of the LM321 (6712) quad op-amp. When stopped, the voltage is about the 10.3V as indicated. When I press play, the voltage drops for a second to about -4.3V, but quickly returns to 10.3V, as the CD stops rotating, and the "--" is shown in the display.
The voltages on the basis of BD135/136 is close to the +/-11.5V as specified.
Because the swing arm moves, when powered off, I assume the CDM-0 drive (which is installed in my 104) works fine, and the problem should be found on the SERVO print.
I have changed all the electrolytic capacitors on the SERVO print to the exact values. I have read, that especially the 33uF capacitor values are important.
I have re-soldered all the plugs on the print, and also all the transistors, which were swimming in solder.
Do you think it would be a good idea to insert new BD135/136 transistors, and a new uA741 operational amplifier?
I am so excited to get this old fantastic CD player working again. I would appreciate any help on locating the cause of my problem. I do not hope I ruined it by manually moving the swing arm, while it was working. But since I did that, it has never moved again :-(
Best regards
Thomas from Denmark.
Hi everybody.
Even though I have read a lot of fantastic postings in this forum, I just recently became a member.
And I hope all you guys with many years of Philips CD 104 experience can help me in the right direction.
The story is, that I just bought this player cheap, hoping to fix it using all your good advices. The griplets and other solderings have been fixed.
The player acts the same before and after having done the basic treatment. When putting a CD in, it can read the TOC. But when I want to play a track, the swing arm moves from side to side, without playing anything.
Eventually I manually tried to move the swing arm in action. When I moved it, it tried to get back to another position. Eventually it does not move anymore.
Service Loop A works fine, but Service Loop B slows down the disc rotation, and eventually ends saying f.ex. "-2 0000" in the display. Sometimes "-1 0000". The swing arm does not move at all, and stays fixed in the center position. The disc keeps rotating.
The radial motor amplifier transistors BD135/136 (6241/6240) gets pretty hot. I can hardly hold my finger on it.
When I switch off the CD player, the swing arm moves half the way op and back. So it seems like the radial motor amplifier works somehow.
I have checked all the static voltages on the SERVO 2 diagram, and they all seem fine. Apart from the voltage on pin 1 of the LM321 (6712) quad op-amp. When stopped, the voltage is about the 10.3V as indicated. When I press play, the voltage drops for a second to about -4.3V, but quickly returns to 10.3V, as the CD stops rotating, and the "--" is shown in the display.
The voltages on the basis of BD135/136 is close to the +/-11.5V as specified.
Because the swing arm moves, when powered off, I assume the CDM-0 drive (which is installed in my 104) works fine, and the problem should be found on the SERVO print.
I have changed all the electrolytic capacitors on the SERVO print to the exact values. I have read, that especially the 33uF capacitor values are important.
I have re-soldered all the plugs on the print, and also all the transistors, which were swimming in solder.
Do you think it would be a good idea to insert new BD135/136 transistors, and a new uA741 operational amplifier?
I am so excited to get this old fantastic CD player working again. I would appreciate any help on locating the cause of my problem. I do not hope I ruined it by manually moving the swing arm, while it was working. But since I did that, it has never moved again :-(
Best regards
Thomas from Denmark.
Diagnosing something like this at a distance is near impossible... so just some quick thoughts.
The two transistors should only get hot if the output is supplying current... so it might be worth disconnecting connector 23-4 to the radial motor and confirming they now run cold. Its an unusual output stage with the opamp output being grounded, which means it then relies on the increase in opamp supply current to turn on the transistors via the volt drop across the 120 ohm supply feed resistors.
If you do change the opamp (its almost certainly 100% OK) then use a genuine 741, do not be tempted fit anything of better performance as the circuit is designed around that particular device.
You will not cause damage manually moving a swing arm, but if the radial motor coils are continually fed with a high voltage under fault conditions then that could cause overheating within the coils.
The two transistors should only get hot if the output is supplying current... so it might be worth disconnecting connector 23-4 to the radial motor and confirming they now run cold. Its an unusual output stage with the opamp output being grounded, which means it then relies on the increase in opamp supply current to turn on the transistors via the volt drop across the 120 ohm supply feed resistors.
If you do change the opamp (its almost certainly 100% OK) then use a genuine 741, do not be tempted fit anything of better performance as the circuit is designed around that particular device.
You will not cause damage manually moving a swing arm, but if the radial motor coils are continually fed with a high voltage under fault conditions then that could cause overheating within the coils.
Hi Mooly.
Thank you very much for your quick and very useful comment. I wondered why the 741 output was grounded. Now I know What an alternative way of using an opamp. Using the supply current is used to controll the radial motor amplifier.
Good idea to disconnect the 23-4 connector. I tried that, and now the the transistors do NOT get very hot. That means, that the coil in the radial arm kind of works, I assume. Also the fact, that the arm moves when I turn off the CD gives me indication, that the radial arm and amp works. I will try to feed the radial arm with current from a power supply to see, if I can controll it that way.
Regarding the pretty hot transistors, I have read this interesting post here:
1984 Philips CD104 CD player restoration - UK Vintage Radio Repair and Restoration Discussion Forum
"
However, Ron discovered a continuing potential problem in the machine, the radial servo BD136 replacement transistor gets rather hot (70+ degrees C), but only when the machine is idle with a disc still in the tray. Ron worked out that the MAB8440P-041 chip microDAC output was causing this as it was continuing to drive the radial servo, but interestingly, when a later MAB8440P-061 chip borrowed from the other CD104B machine was fitted in this one, the problem went away. Thinking maybe this was a faulty chip, I placed an ad on the forum for a spare chip and Mick (Mickmcmichael) very kindly sent me a spare MAB8440P-041 chip .... which behaved in exactly the same way as the original chip. So we have concluded that this is a 'feature' of this particular CD104 model which was corrected in the later CD104B model.
"
So - maybe it is okay, that these transistors get hot when idle with at CD mounted?
I have to look at the other components like 6211, 6214, 6215, 6212 and maybe the discrete transistors and diodes.
It is so frustrating that the arm previously moved (but player did not work) and now don't. All voltages seems fine, and the signal on 6212 pin 1 is 10.3V, and shortly the correct -4.3V, before giving up :-(
Thank again, Mooly. You gave me new energy to continue trying to get this old machine working again.
Best regards
Thomas.
Thank you very much for your quick and very useful comment. I wondered why the 741 output was grounded. Now I know
What an alternative way of using an opamp. Using the supply current is used to controll the radial motor amplifier.Good idea to disconnect the 23-4 connector. I tried that, and now the the transistors do NOT get very hot. That means, that the coil in the radial arm kind of works, I assume. Also the fact, that the arm moves when I turn off the CD gives me indication, that the radial arm and amp works. I will try to feed the radial arm with current from a power supply to see, if I can controll it that way.
Regarding the pretty hot transistors, I have read this interesting post here:
1984 Philips CD104 CD player restoration - UK Vintage Radio Repair and Restoration Discussion Forum
"
However, Ron discovered a continuing potential problem in the machine, the radial servo BD136 replacement transistor gets rather hot (70+ degrees C), but only when the machine is idle with a disc still in the tray. Ron worked out that the MAB8440P-041 chip microDAC output was causing this as it was continuing to drive the radial servo, but interestingly, when a later MAB8440P-061 chip borrowed from the other CD104B machine was fitted in this one, the problem went away. Thinking maybe this was a faulty chip, I placed an ad on the forum for a spare chip and Mick (Mickmcmichael) very kindly sent me a spare MAB8440P-041 chip .... which behaved in exactly the same way as the original chip. So we have concluded that this is a 'feature' of this particular CD104 model which was corrected in the later CD104B model.
"
So - maybe it is okay, that these transistors get hot when idle with at CD mounted?
I have to look at the other components like 6211, 6214, 6215, 6212 and maybe the discrete transistors and diodes.
It is so frustrating that the arm previously moved (but player did not work) and now don't. All voltages seems fine, and the signal on 6212 pin 1 is 10.3V, and shortly the correct -4.3V, before giving up :-(
Thank again, Mooly. You gave me new energy to continue trying to get this old machine working again.
Best regards
Thomas.
Now I did some more research on my 104'er.
With the connector 23-4 disconnected, I tried to put voltage directly on the rotation arm. And the good thing is, that I can control the arm position by changing the voltage. Strange enough, only about 1V gave full rotation. But I assume that is okay.
Then I measured the voltage on the 24-4 output plug from the radial motor amplifier. And it is constantly about 11.5V. To me it indicates, that the BD135 and/or BD136 might be blown (short circuited).
I double-checked pin 6 (741 output) to verify, that the griplet here is okay. And it is - pin 6 is 0V.
I also changed one transistor (BC548/6243) and 3 diodes (BAW62/6249, 6250, 6255). All in the radial motor control circuit. That did not help.
All these observations leeds me to the idea of changing the BD135/136 transistors, and maybe also the 741 (even though I think it is okay).
Thank you for reading about all my troubles with this old machine
Best regards
Thomas.
With the connector 23-4 disconnected, I tried to put voltage directly on the rotation arm. And the good thing is, that I can control the arm position by changing the voltage. Strange enough, only about 1V gave full rotation. But I assume that is okay.
Then I measured the voltage on the 24-4 output plug from the radial motor amplifier. And it is constantly about 11.5V. To me it indicates, that the BD135 and/or BD136 might be blown (short circuited).
I double-checked pin 6 (741 output) to verify, that the griplet here is okay. And it is - pin 6 is 0V.
I also changed one transistor (BC548/6243) and 3 diodes (BAW62/6249, 6250, 6255). All in the radial motor control circuit. That did not help.
All these observations leeds me to the idea of changing the BD135/136 transistors, and maybe also the 741 (even though I think it is okay).
Thank you for reading about all my troubles with this old machine
Best regards
Thomas.
I somehow doubt the transistor will be faulty although of course you have to check. They will conduct if the volt drop across the 120 ohm exceeds around 0.6 volts. If the offset is positive then that means R3381 would be the one with the volt drop, R3382 would be well below that threshold.
Isolating pin 6 of the opamp should bring the offset to near zero as no significant voltage can be developed across either of the 120 ohm resistors... so a simple check in itself of what is happening.
The DC voltage on pin 3 of the opamp will essential determine what happens at the output stage but this is a very difficult circuit to analyse because there is an additional AC 'wobble' component fed into pin 2 of the opamp from earlier opamp 6215.
You mention earlier that it can read the TOC. That kind of suggests that the radial circuit is at least basically functional. I think the first thing you need to do is to look at the RF from the pickup when reading the TOC and confirm that it is at the expected amplitude of around 1.2 volts pk/pk. That would be a big clue as to the goodness of the laser and optics.
Isolating pin 6 of the opamp should bring the offset to near zero as no significant voltage can be developed across either of the 120 ohm resistors... so a simple check in itself of what is happening.
The DC voltage on pin 3 of the opamp will essential determine what happens at the output stage but this is a very difficult circuit to analyse because there is an additional AC 'wobble' component fed into pin 2 of the opamp from earlier opamp 6215.
You mention earlier that it can read the TOC. That kind of suggests that the radial circuit is at least basically functional. I think the first thing you need to do is to look at the RF from the pickup when reading the TOC and confirm that it is at the expected amplitude of around 1.2 volts pk/pk. That would be a big clue as to the goodness of the laser and optics.
Thanx again, Mooly.
Why I think one of the BD transistors might be dead is, that initially the radial arm moved fine, and I was able to read TOC. But when pressing play, the radial arm keeps searching on the disc.
Once while it was searching, I manually move the radial arm, after which it moved back and continued searching. Eventually the arm did not move anymore, so I am afraid I destroyed something when manually moving the arm while it was working.
And since the 24-4 output pin to the rotating arm coil is constantly 11.5V it could indicate, that one of the BD transistors is blown.
Anyway - I just ordered some new transistors, and hope that will at least bring my CD back to its initial state: TOC Ok, but play NoK.
Best regards
Thomas.
Why I think one of the BD transistors might be dead is, that initially the radial arm moved fine, and I was able to read TOC. But when pressing play, the radial arm keeps searching on the disc.
Once while it was searching, I manually move the radial arm, after which it moved back and continued searching. Eventually the arm did not move anymore, so I am afraid I destroyed something when manually moving the arm while it was working.
And since the 24-4 output pin to the rotating arm coil is constantly 11.5V it could indicate, that one of the BD transistors is blown.
Anyway - I just ordered some new transistors, and hope that will at least bring my CD back to its initial state: TOC Ok, but play NoK.
Best regards
Thomas.
good luck.Did anyone ever deal with the problem that all electronics -including the boards on the CDM-1 itself -work but the player still does not read?
Eyepattern seems to be ok in amplitude in the rare moments when the laser locks to read TOC.
Arm moves freely. I know that it must be a problem with the laser / mechanics as I have a spare CDM-1.
Again I evem swapped the boards on the CDM-1 for testing and the spare CDM worked witn the boards of the defective one.
Before this happened I did a complete swap of all capacitors and found a way to align the swing arm by measuring the focus signal:
http://www.diyaudio.com/forums/digi...-cdm-1-swing-arm-alignment-4.html#post5020778
After this, the player (Philips CD-304MKII) worked for about two months...
Eyepattern seems to be ok in amplitude in the rare moments when the laser locks to read TOC.
Arm moves freely. I know that it must be a problem with the laser / mechanics as I have a spare CDM-1.
Again I evem swapped the boards on the CDM-1 for testing and the spare CDM worked witn the boards of the defective one.
Before this happened I did a complete swap of all capacitors and found a way to align the swing arm by measuring the focus signal:
http://www.diyaudio.com/forums/digi...-cdm-1-swing-arm-alignment-4.html#post5020778
After this, the player (Philips CD-304MKII) worked for about two months...
Hi - I am back
I have a good and a bad experience.
The good is, that after having changed the BD135/136 transistors and the 741 opamp, my rotating arm is working again. I guess these transistors have been changed before, because BD136 had been changed to a BD231. Equivalent yes, but a little weaker ampere and power wise.
The bad is, that after having done this, and all the griplets, and renewied a lot of capacitors, it is no longer able to read TOC. I can hear the rotating arm work heavily for a couple of seconds, before it gives up
Service mode A works, and Service mode B likewise works apart from never ends, and no music. The rotating arm is working like crazy around the TOC.
Hmm - what a pity. I have to take a rest, and look at it again tomorrow.
Best regards
Thomas.
I have a good and a bad experience.
The good is, that after having changed the BD135/136 transistors and the 741 opamp, my rotating arm is working again. I guess these transistors have been changed before, because BD136 had been changed to a BD231. Equivalent yes, but a little weaker ampere and power wise.
The bad is, that after having done this, and all the griplets, and renewied a lot of capacitors, it is no longer able to read TOC. I can hear the rotating arm work heavily for a couple of seconds, before it gives up
Service mode A works, and Service mode B likewise works apart from never ends, and no music. The rotating arm is working like crazy around the TOC.
Hmm - what a pity. I have to take a rest, and look at it again tomorrow.
Best regards
Thomas.
I have a small question to all you experts I have now changed all the electrolytic capacitors on the decoder board as well, and my 104 has become a little better. It can sometimes read TOC - sometimes not. But it can never play. It tries hard for a minute or so, before giving up with "--" in the display.
My question is: Is it advisable to also change the 5-6 electrolytic capacitors on the CDM-0 print board as well? How important are they?
Best regards
Thomas.
I have now changed all the electrolytic capacitors on the decoder board as well, and my 104 has become a little better. It can sometimes read TOC - sometimes not. But it can never play. It tries hard for a minute or so, before giving up with "--" in the display.My question is: Is it advisable to also change the 5-6 electrolytic capacitors on the CDM-0 print board as well? How important are they?
Best regards
Thomas.
Absolutely yes, they have got to be replaced, in particular the two related to the laser drive and monitoring circuit C2140 and 2144. Replace them all and do not alter values.
I should have realised when you mentioned replacing the caps on the servo board that you were referring to the main PCB. Its probably from working on the later models that I always mentally refer to the PCB under the pickup as the 'Servo' and the main PCB as the 'Decoder'.
Yes, get them changed
I should have realised when you mentioned replacing the caps on the servo board that you were referring to the main PCB. Its probably from working on the later models that I always mentally refer to the PCB under the pickup as the 'Servo' and the main PCB as the 'Decoder'.
Yes, get them changed
