Volvo Owners Club Forum - View Single Post - Stereo/DVD: - "Auxiliary In" Hack for HU-6XX series

pierremcalpine · Jan 22nd, 2013, 13:46

Posting purely for entertainment...

So I took it a step further and continued the quest to gain access to the underside of the main board of the HU. Turns of that you need to take the entire HU appart to be able to remove the bottom panel (on the HU-615 anyway). You then have to be able to put it back together in a manner than still allows access to the underside which meant putting the back and sides back on and using some electric tape to support the CD player in its place.

Brought it back in the car, plugged it in upside down and proceeded to find a good point to connect to for audio.

Took quite a while as there is absolutely no helpful notation on the underside of the panel. The only points that gave reasonable sound where the four connections near the output of the amplifier. I did not like the four points instead of two and my instincts were telling me that something was up but I ignored them and forged ahead. Some trial and error indicated which were left and which were right so I took the unit back into the house for soldering.

I first took a small piece of insulated wire and soldered the lefts together as well as the rights (again the instincts were in high gear advising that this was probably not a good idea but ignored them as the sound was quite crisp (and loud) from these connect points). I then soldered on an audio cable (L and R) + grounded on a screw inside the unit.

Put the whole thing back together (without any screws left over) and hurried out to the car to give it a go.

Plugged it in and sound was fantastic! Turned the volume down but...what's this? No volume control? Tried to adjust base and treble...oh oh, no base and treble. Changed from CD to Radio and my blackberry continued to blare through the radio signal. Turned the Radio volume right down and got really nice sound out of the blackberry. Crap.

Long story short, when a device is plugged in it pumps the signal in over top of whatever is playing be it a blank CD (which was my original plan) or FM/AM radio. Furthermore, the sound is totally reliant on the quality of the amp in the portable device (in my case a Blackberry) so the treble is good but base is not strong.

So basically what I've done (I believe) is connect to a point in the circuit "after" the volume has been inserted (+ other audio controls) and therefore I am not able to use any of the HU's native functions. Theoretically all I need to do is trace the signal backwards until I find the point at which the audio controls are inserted...I'm curious as to whether such a point exists on this board or whether the "front" PCB is the one that needs to be looked at. If this is the case, I'll need to also take off the face and put the unit back together without it in order to fish around to find a good connection point...that would be tough.

I may have to give up for a while as I regain my sanity and will post if/when I give this another go.

Jan 22nd, 2013, 13:46	#12
pierremcalpine Premier Member Last Online: Jan 3rd, 2024 14:43 Join Date: Feb 2012 Location: Toronto Canada	Another Update Posting purely for entertainment... So I took it a step further and continued the quest to gain access to the underside of the main board of the HU. Turns of that you need to take the entire HU appart to be able to remove the bottom panel (on the HU-615 anyway). You then have to be able to put it back together in a manner than still allows access to the underside which meant putting the back and sides back on and using some electric tape to support the CD player in its place. Brought it back in the car, plugged it in upside down and proceeded to find a good point to connect to for audio. Took quite a while as there is absolutely no helpful notation on the underside of the panel. The only points that gave reasonable sound where the four connections near the output of the amplifier. I did not like the four points instead of two and my instincts were telling me that something was up but I ignored them and forged ahead. Some trial and error indicated which were left and which were right so I took the unit back into the house for soldering. I first took a small piece of insulated wire and soldered the lefts together as well as the rights (again the instincts were in high gear advising that this was probably not a good idea but ignored them as the sound was quite crisp (and loud) from these connect points). I then soldered on an audio cable (L and R) + grounded on a screw inside the unit. Put the whole thing back together (without any screws left over) and hurried out to the car to give it a go. Plugged it in and sound was fantastic! Turned the volume down but...what's this? No volume control? Tried to adjust base and treble...oh oh, no base and treble. Changed from CD to Radio and my blackberry continued to blare through the radio signal. Turned the Radio volume right down and got really nice sound out of the blackberry. Crap. Long story short, when a device is plugged in it pumps the signal in over top of whatever is playing be it a blank CD (which was my original plan) or FM/AM radio. Furthermore, the sound is totally reliant on the quality of the amp in the portable device (in my case a Blackberry) so the treble is good but base is not strong. So basically what I've done (I believe) is connect to a point in the circuit "after" the volume has been inserted (+ other audio controls) and therefore I am not able to use any of the HU's native functions. Theoretically all I need to do is trace the signal backwards until I find the point at which the audio controls are inserted...I'm curious as to whether such a point exists on this board or whether the "front" PCB is the one that needs to be looked at. If this is the case, I'll need to also take off the face and put the unit back together without it in order to fish around to find a good connection point...that would be tough. I may have to give up for a while as I regain my sanity and will post if/when I give this another go.