another question on the TDA1541A..
Hi all,
I'm playing with a TDA1541A and have noticed a odd behaviour from one chip: as soon as I apply power it sounds distorted but when I start checking pin voltages with my oscilloscope as soon as I touch pin 17 sound becomes OK and stays like that.
It looks like the DEM oscillator has troubles starting the oscillation.... btw I use a 470pF cap.
This happens with a chip dated 1994, while another chip dated 1997 works fine....
Any clue about that?
Cheers
Andrea
Hi all,
I'm playing with a TDA1541A and have noticed a odd behaviour from one chip: as soon as I apply power it sounds distorted but when I start checking pin voltages with my oscilloscope as soon as I touch pin 17 sound becomes OK and stays like that.
It looks like the DEM oscillator has troubles starting the oscillation.... btw I use a 470pF cap.
This happens with a chip dated 1994, while another chip dated 1997 works fine....
Any clue about that?
Cheers
Andrea
Some chips have built in cap.
Check with test CD and low level sine wave.
If the oscillator is not working gross crossover distortion
Check with test CD and low level sine wave.
If the oscillator is not working gross crossover distortion
tubee said:
Err... do you mean that the DEM oscillator needs to leak some current to properly start?😕
QSerraTico_Tico said:
The TDA1541 has the cap built-in .
The 1541A doesn't.
No need to check with sine, music is very distorted until I touch the pin 17 with my oscilloscope probe.
I am just asking if anyone experienced this problem and if found a way to cure it (bigger/ different cap, etc...)
Cheers
Andrea
Addendum to the oddities
Hi,
while testing some chips I plugged in a TDA1541.
This chip is supposed to have a internal DEM oscillator cap (datasheet shows pin 16 and 17 unconnected).
To my surprise leaving them disconnected distortion was rocket high. Putting the cap in made it lower to reasonable levels.
Using DEM reclock lowered it further. Go figure!
The chip used is late 1541 production (1987, and also has a Y printed, that, if I recall correctly, was mentioned to be meaning "development sample")....maybe a early 1541A?
Anyone had similar experience?
Cheers
Andrea😕
Hi,
while testing some chips I plugged in a TDA1541.
This chip is supposed to have a internal DEM oscillator cap (datasheet shows pin 16 and 17 unconnected).
To my surprise leaving them disconnected distortion was rocket high. Putting the cap in made it lower to reasonable levels.
Using DEM reclock lowered it further. Go figure!
The chip used is late 1541 production (1987, and also has a Y printed, that, if I recall correctly, was mentioned to be meaning "development sample")....maybe a early 1541A?
Anyone had similar experience?
Cheers
Andrea😕
I am a strong believer the TDA1541 nor the 1541-A cannot function without the dem cap or an external provided dem signal.
hi,
so why release a chip that doesn't work as stated in the datasheet? 😕
BTW did you happen to look at the DEM reclock signals with your scope? I use HtP's original schematic and I see a rather large negative peak (will take a photo soon).
Cheers
Andrea
so why release a chip that doesn't work as stated in the datasheet? 😕
BTW did you happen to look at the DEM reclock signals with your scope? I use HtP's original schematic and I see a rather large negative peak (will take a photo soon).
Cheers
Andrea
Philips did some curious things with the 1541.
I have looked at the dem signal, but it is for a while now, can't remember exactly.
Btw sit right here listening to Rush, Signals, with a plain 1541 (no A) in CD304mk2 with the dem clock, not HtP's but Ec's
I have looked at the dem signal, but it is for a while now, can't remember exactly.
Btw sit right here listening to Rush, Signals, with a plain 1541 (no A) in CD304mk2 with the dem clock, not HtP's but Ec's
I used to work for a large european semiconductor manufacturer (not Philips) and I can say, as useful as they are, datasheets can be wrong at times.
Hi,
This is certainly possible, but I doubt nobody verified it.
Surely there are players around with TDA1541 and without the Cosc cap
Example:
Does anybody have a direct experience?
Cheers
Andrea
edit: maybe the Cosc is under the green ceramic...wrong example in that case
This is certainly possible, but I doubt nobody verified it.
Surely there are players around with TDA1541 and without the Cosc cap
Example:
An externally hosted image should be here but it was not working when we last tested it.
Does anybody have a direct experience?
Cheers
Andrea
edit: maybe the Cosc is under the green ceramic...wrong example in that case
Hi,
the picture was taken on the net, so I can't flip the PCB and see underneath.
The question about TDA1541 (without A) remains the same.
Surely someone around here has a player with such a chip....
Cheers
Andrea
the picture was taken on the net, so I can't flip the PCB and see underneath.
The question about TDA1541 (without A) remains the same.
Surely someone around here has a player with such a chip....
Cheers
Andrea
Katapum,
the photo in the post you link shows that the PCB had a provision for the Cosc capacitor but it seems that it wasn't mounted. Or did you remove it?
Can you confirm?
Cheers
Andrea
the photo in the post you link shows that the PCB had a provision for the Cosc capacitor but it seems that it wasn't mounted. Or did you remove it?
Can you confirm?
Cheers
Andrea
)
- Status
- Not open for further replies.