Ok, just some news: I measured the voltages on the 7918. If I'm right, should be the 2nd from left, the one from wich I uploaded a picture, with a silly gold coloration...
Input: -20,7 volt
Output: -12,3 volt
As far as I know, it should be -18Volt, at least from the spec sheet! If someone know how much it should be at the input pin, I could for sure know if the problem is coming from a defective cap or from the 7918 itself!
Thanks all!
Input: -20,7 volt
Output: -12,3 volt
As far as I know, it should be -18Volt, at least from the spec sheet! If someone know how much it should be at the input pin, I could for sure know if the problem is coming from a defective cap or from the 7918 itself!
Thanks all!
Hi,
Doesn't sound quite right. The 7918 is a negative 18 volt reg see
http://www.datasheetcatalog.org/datasheet2/3/07wj61wwrjxhoxd4gwe1k51sg5py.pdf
Not a 7912 is it ?
Doesn't sound quite right. The 7918 is a negative 18 volt reg see
http://www.datasheetcatalog.org/datasheet2/3/07wj61wwrjxhoxd4gwe1k51sg5py.pdf
Not a 7912 is it ?
Mooly said:
Sorry, I of course mean -30 or -32 volts!
Scope is saddly at work... Was 7 o' clock pm as I went from work, I had nothing to eat since yesterday evning, so I forgot the scope!
Will get it tomorrow. Hmm, wich cable should I take? The normal ones or the HF ones?
No idea if the regulator is going hot, I'll check this now! I can read "something"18"something", so I assume this is a 18volt regulator
Silly question: the regs are mounted directly on the heatsink which is direcly linked to the ground! Is that a prefect configuration for ground loop? Should I insulate the regs (mica sheet)?
If you are not sure if it is the correct reg, then with the CD Player off and unplugged ( as any residual voltage totally confuses DVM's on ohms) measure continuity on a low ohms range from pin 11 on the TDA ( the -18 volt rail ) to the reg you suspect.
If thats OK work further back seeing where the input pin to the 7918 goes. It may be worth just replacing this reg anyway as it has been mentioned a few times as causing problems. It's not one of the more common voltages so if you can't get one locally, a 7912 and a 6.8 volt zener ( small 400mw or 1.3 watt ) or a 7915 and 3.3 volt zener will do. Can show how to fit the zener to lift the voltage -- it's a recognised trick Check also any low value resistors ( if there are any ) feeding the inputs to these regs as Philips love using these. Any fault may cause one or more to go high in value.
If thats OK work further back seeing where the input pin to the 7918 goes. It may be worth just replacing this reg anyway as it has been mentioned a few times as causing problems. It's not one of the more common voltages so if you can't get one locally, a 7912 and a 6.8 volt zener ( small 400mw or 1.3 watt ) or a 7915 and 3.3 volt zener will do. Can show how to fit the zener to lift the voltage -- it's a recognised trick
Check also any low value resistors ( if there are any ) feeding the inputs to these regs as Philips love using these. Any fault may cause one or more to go high in value.Sorry, I was without internet until now!
Here are the results for the measurments on the regs!
Top view, from left to rigt, pin layout:
As I don't have the pcb layout, I can't be sure if the value are what they should be! On top of this, I can't read the ref. of the regs! Next thing that I'll have to to: get a little mirror and try to decipher what's wrotten on the regs!
But for sure is that I missed the -18 volt reg in my first measurement!
I hpe that I'll have the scipe tonight and time to dismantle the cage so I can measure the values at the TDA inputs!
Here are the results for the measurments on the regs!
Top view, from left to rigt, pin layout:
Code:
| | | |
+20,0 V +11,9 V | 0,0 V -12,3 V | -17,0 V -18,3 V | +3,8 V +11,7 V | -6,0 V -7,3 V
-0,1 V | -21,0 V | -26,0 V | +5,0 V | -13,8 V
| | | |As I don't have the pcb layout, I can't be sure if the value are what they should be! On top of this, I can't read the ref. of the regs! Next thing that I'll have to to: get a little mirror and try to decipher what's wrotten on the regs!
But for sure is that I missed the -18 volt reg in my first measurement!
I hpe that I'll have the scipe tonight and time to dismantle the cage so I can measure the values at the TDA inputs!
Hi there! 
Still alive! I opened the "cage" this afternoon: it's no fun, believe me... Don't know how I'll get it closed Now is everything back in place, just missing the top of the cage as I wanted to measure inside the problem child.
Before continuing, many many thanks to Mooly who helped me a lot with advices in his mails!
Now let's start!
Output at the power board:
That looks nice,
now both TDA1540D (left is left on the pcb an so on...)
Once again, looks nice (maybe the -3,7 noisy... should be -3,8 clean...
Both NE5532
That looks nice too...
So, if someone has an idea...
Maybe I'll try to swap the 1540 later this afternoon, but I'm not so confortable with this. I fear that I'll bend one or more leg :/
Oh, if someone is interessed, I've all the voltage for every legs of every Opamp... As the voltage "form", sinus... (only the measured values, not the theoretical!!!)
Thanks!
Still alive! I opened the "cage" this afternoon: it's no fun, believe me... Don't know how I'll get it closed
Now is everything back in place, just missing the top of the cage as I wanted to measure inside the problem child.Before continuing, many many thanks to Mooly who helped me a lot with advices in his mails!
Now let's start!
Output at the power board:
Code:
-12,0 V +05,4 V +12,0 V -7,3 V -00,1 V -18,x VThat looks nice,
now both TDA1540D (left is left on the pcb an so on...)
Code:
pin 4: +3,7 V (noisy!) pin 4: +3,8 V (clean)
pin 7: -6,45 V pin 7: -6,40 V
pin 11: -18 V pin 11: -18 VOnce again, looks nice (maybe the -3,7 noisy... should be -3,8 clean...
Both NE5532
Code:
pin 4: -12,2 V pin 4: -12,2 V
pin 8: +11,8 V pin 8: +11,8 VThat looks nice too...
So, if someone has an idea...
Maybe I'll try to swap the 1540 later this afternoon, but I'm not so confortable with this. I fear that I'll bend one or more leg :/
Oh, if someone is interessed, I've all the voltage for every legs of every Opamp... As the voltage "form", sinus... (only the measured values, not the theoretical!!!)
Thanks!
Pin4 should be +5v
Pin7 should be -5v
Pin11 should be -12v
all should be "clean" with little noise.
Are you sure that your ground was good? Pin6 is gnd.
TDA1540 Datasheet:-
http://pdf1.alldatasheet.com/datasheet-pdf/view/82318/ETC/TDA1540.html
Andy
Pin7 should be -5v
Pin11 should be -12v
all should be "clean" with little noise.
Are you sure that your ground was good? Pin6 is gnd.
TDA1540 Datasheet:-
http://pdf1.alldatasheet.com/datasheet-pdf/view/82318/ETC/TDA1540.html
Andy
Yeap, maybe thesere the values from the datasheet (I didn't checked!), but from the SM, values should be:
pin 4: +3,8 V
pin 7: -6,3 V
pin 11: -18 V
Scope was grounded on the "cage", which is the audio ground, so should be fine!
Nisy or not: hmm, well, maybe I should make a pic and post it here, as noisy for me is maybe not noisy for you...
pin 4: +3,8 V
pin 7: -6,3 V
pin 11: -18 V
Scope was grounded on the "cage", which is the audio ground, so should be fine!
Nisy or not: hmm, well, maybe I should make a pic and post it here, as noisy for me is maybe not noisy for you...
If i understand correctly one channel still has (nearly) no sound
output.
Here's a suggestion based on recent experience with a CD104:
C2723 left channel or C2758 right channel.
In one of my CD104's which I bought as spares the right channel
did not produce sound. Only very light crackling noise.
I used a CD with a recorded tone of 1000Hz and found that
the signal appeared at pin 7 of both NE5532's. But not at the
KILL switch in the right channel. So I desoldered both capacitors
and measured them with a LCR meter.
The left one was some 15uF and the right one was open.
I then proceded mounting two new 22uF nichinon and the player
was well again.
The CD 104 has a famous ailment called griplet's. I don't know
if the CD303 uses something similar. But if it does, you might
want to fix that right away.
Hope this helps
output.
Here's a suggestion based on recent experience with a CD104:
C2723 left channel or C2758 right channel.
In one of my CD104's which I bought as spares the right channel
did not produce sound. Only very light crackling noise.
I used a CD with a recorded tone of 1000Hz and found that
the signal appeared at pin 7 of both NE5532's. But not at the
KILL switch in the right channel. So I desoldered both capacitors
and measured them with a LCR meter.
The left one was some 15uF and the right one was open.
I then proceded mounting two new 22uF nichinon and the player
was well again.
The CD 104 has a famous ailment called griplet's. I don't know
if the CD303 uses something similar. But if it does, you might
want to fix that right away.
Hope this helps
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