Hello folks!
Hope someone can help me with a stupid idea I have. I had an old hifi system lying around and I thought to add an AUX input to so i can use it with my PC/laptop/mobile to listen to music. The model is "Thomson AM1080"
Did a bit of research and from that I understood I had two options:
1: Use the radio receiver to intercept the signal
2: Use the CD player
Since the radio is integrated in the mainboard decided to go with the cdplayer cos it had a separate module and it would be easier to intercept. Found the cable connecting cdplayer module to the mainboard, cut the wires and connected 3.5mm cable I intented to use and to my surprise it kinda worked, I got the sound from the speakers easy like that. Problem is the sound was very low and distorted even with all volumes up! It was even lower than when connecting the speakers directly to my laptop. And more to that when i connected the speakers directly to my laptop the sound was low but at least clean.
So my theory was to intercept the preamped signal somewhere (in this case the CD Player). Than let it go through the mainboard, let the chips, amps, ICs do their magic and get a nice amped signal to the speakers but clearly I went wrong somewhere.
Now I have to add that from the CDplayer module there were 8 cables going out. 3 of them went to the control board and I did not touch them. The other 5 traveled together to the mainboard. The first two are labeled DGND and CD10V and I didnt touch them either. The other three are labeled CDR - AGND - CDL. These were the ones i connected my laptop signal in. Im also attaching a pic of my connection below. (Im sure Ive done the connection right. Weird as it sounds the orange wire from my 3.5mm cable is the ground, doublechecked it with multimeter)
http://oi66.tinypic.com/34hdj5v.jpg
Also made some tests using the cassette module but again got the same low distorted sound as in CD player. with the exception it was more complicated as there were way more outputs getting out from it. I see no need to describe that too in details.
Also tried to find the schematics/servise manual for it online to see if i could understand a bit more but didnt find it anywhere.
I feel necessary to add that my knowledge is very limited. I can understand a bit of the basics how stuff works, can make simple use of my multimeter, can solder things but thats it.
Im sorry that my English is not very good but its not my native language. Although I think im understandable!
Any help, advice, suggestion or question would be very welcomed
Hope someone can help me with a stupid idea I have. I had an old hifi system lying around and I thought to add an AUX input to so i can use it with my PC/laptop/mobile to listen to music. The model is "Thomson AM1080"
Did a bit of research and from that I understood I had two options:
1: Use the radio receiver to intercept the signal
2: Use the CD player
Since the radio is integrated in the mainboard decided to go with the cdplayer cos it had a separate module and it would be easier to intercept. Found the cable connecting cdplayer module to the mainboard, cut the wires and connected 3.5mm cable I intented to use and to my surprise it kinda worked, I got the sound from the speakers easy like that. Problem is the sound was very low and distorted even with all volumes up! It was even lower than when connecting the speakers directly to my laptop. And more to that when i connected the speakers directly to my laptop the sound was low but at least clean.
So my theory was to intercept the preamped signal somewhere (in this case the CD Player). Than let it go through the mainboard, let the chips, amps, ICs do their magic and get a nice amped signal to the speakers but clearly I went wrong somewhere.
Now I have to add that from the CDplayer module there were 8 cables going out. 3 of them went to the control board and I did not touch them. The other 5 traveled together to the mainboard. The first two are labeled DGND and CD10V and I didnt touch them either. The other three are labeled CDR - AGND - CDL. These were the ones i connected my laptop signal in. Im also attaching a pic of my connection below. (Im sure Ive done the connection right. Weird as it sounds the orange wire from my 3.5mm cable is the ground, doublechecked it with multimeter)
http://oi66.tinypic.com/34hdj5v.jpg
Also made some tests using the cassette module but again got the same low distorted sound as in CD player. with the exception it was more complicated as there were way more outputs getting out from it. I see no need to describe that too in details.
Also tried to find the schematics/servise manual for it online to see if i could understand a bit more but didnt find it anywhere.
I feel necessary to add that my knowledge is very limited. I can understand a bit of the basics how stuff works, can make simple use of my multimeter, can solder things but thats it.
Im sorry that my English is not very good but its not my native language. Although I think im understandable!
Any help, advice, suggestion or question would be very welcomed
Hard to make out from pictures how its all connected. First thought though, you can not connect an output (your PC/Mobile etc) across an output (the CD or radio feeds) because they are effectively a low impedance point. That means the PC etc is working into a short.
Is that what you have done ?
And welcome to diyAudio Your English is perfect.
Is that what you have done ?
Im sorry that my English is not very good but its not my native language. Although I think im understandable!
Any help, advice, suggestion or question would be very welcomed
And welcome to diyAudio
Your English is perfect.
Hard to make out from pictures how its all connected. First thought though, you can not connect an output (your PC/Mobile etc) across an output (the CD or radio feeds) because they are effectively a low impedance point. That means the PC etc is working into a short.
Is that what you have done ?
And welcome to diyAudio
Thank you for the quick reply
The cable that goes in the board (shown in the picture) is the cable which connects the mainboard with CD player which I cut. I dont think that is an output point since to my understanding it receives audio from the cdplayer (which is a sperate module with its own separate circuit) and than sends it to the AMP in the board and than to the speakers. So instead of CD player signal im sending to the board the signal from my PC and it is kida working as I said cos that signal is going into the board and comming out from the speakers, problem is it is too low and distorted
Just measured it with system on, there wasnt any voltage. What picowallspeaker said is a bit too advanced for me. I saw it on a video but i have to baypass the CDplayer stream locate the audio amp, locate the L.R,GND pins and make the connection there but im not sure that possible with my level of knowledge
Lets start again
The wires you mentioned at the beginning, DGND and CD10V are digital ground and most likely a 10 volt supply to the player.
CDR/CDL and AGND sound like the right and left outputs from the player together with the 'audio' or 'analogue' ground.
So based on that you leave the AGND intact and cut just the CDR and CDL wires.
You then connect the ground of the new audio feed (your PC) to the AGND point and the left and right feeds from the PC to the CDR and CDL points on the main board of the unit.
If a cap were needed then it would go in series with each audio feed (one in the left and one in the right) but if there is no DC voltage present at that point then you should be OK without.
The wires you mentioned at the beginning, DGND and CD10V are digital ground and most likely a 10 volt supply to the player.
CDR/CDL and AGND sound like the right and left outputs from the player together with the 'audio' or 'analogue' ground.
So based on that you leave the AGND intact and cut just the CDR and CDL wires.
You then connect the ground of the new audio feed (your PC) to the AGND point and the left and right feeds from the PC to the CDR and CDL points on the main board of the unit.
If a cap were needed then it would go in series with each audio feed (one in the left and one in the right) but if there is no DC voltage present at that point then you should be OK without.
This is what i have done so far. Connected left and right outputs from my PC to CDL/CDR and ground of my PC to AGND.
DGND and CD10V (yellow and blue in the picture) are left intact (but pretty much doing nothing since I've disconnected the cable from the CD player)
Do you think it safe and worth a try using DGND instead of AGND?
For the caps I have to wait till tomorrow since I dont have any and cant buy them right now.
DGND and CD10V (yellow and blue in the picture) are left intact (but pretty much doing nothing since I've disconnected the cable from the CD player)
Do you think it safe and worth a try using DGND instead of AGND?
For the caps I have to wait till tomorrow since I dont have any and cant buy them right now.
I'm sorry, I missed your reply...
Connecting as you have done sounds correct so long as the CDL and CDR lines are disconnected from the output of the inbuilt player. That is very important.
If you switch off and then measure the resistance between DGND and AGND then I'm sure you will find them one and the same. The only difference is in the way the various parts connect to ground and keeping digital and analogue separate ensures things like the CD player servos and motor current don't cause audible interference.
Just think of them as two wires from a common point. One is called DGND and the other AGND. The only reason this is done is because of the small but non the less significant resistance of all conductors. So keeping 'dirty' items like motors and servos away from the audio is common practice.
Connecting as you have done sounds correct so long as the CDL and CDR lines are disconnected from the output of the inbuilt player. That is very important.
If you switch off and then measure the resistance between DGND and AGND then I'm sure you will find them one and the same. The only difference is in the way the various parts connect to ground and keeping digital and analogue separate ensures things like the CD player servos and motor current don't cause audible interference.
Just think of them as two wires from a common point. One is called DGND and the other AGND. The only reason this is done is because of the small but non the less significant resistance of all conductors. So keeping 'dirty' items like motors and servos away from the audio is common practice.
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