* Panasonic RX-DT680 line-in mod for phones/MP3 players*

jimmyjimmy19702010

Member (SA)
May 5, 2012
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Sunny Brisbane, Australia
Hi Guys,

As mentioned in my recent thread regarding a newly acquired RX-DT680, this morning I've just completed the line-in mod that has now allowed this Panny to become my 'go to' indoor boombox.

I've done the same mod before on my original DT680 and as before, it was a pretty straight forward process.

This mod is suitable for connecting mobile phones/MP3 players. The tape circuit this mod connects to has a higher sensitivity than standard line level line inputs so is not suitable for input sources that do not allow adjustment of the input levels e.g external CD players etc.

This time around, I'm providing a more detailed description of what's involved for anyone out there contemplating the same mod:

1. Remove all the rear screws including the two inside the main battery compartment + the small front screw located behind the volume knob. Open both deck doors and then open the CD cover. Lift up the little tab located at the front of the CD opening and remove the front cover.
C9852AF4-CEA4-491E-BAB2-F62E1C954C3D.jpeg
2. Remove the 3 screws retaining the bottom button switch 'stick assembly' and push aside.

3. Remove the 6 screws retaining the deck assembly. Lift up the deck assembly just enough to allow you to disconnect the two multi pin connectors. The deck assembly can now be removed. One of the multi pin connectors is slightly longer than the other so they can only be reconnected the right way. :-)

4. Turn the unit around and locate the yellow sticker on the rear. This will be the location of your new RCA inputs.

5. Drill two holes in the approximate left to right center of the yellow sticker. Start out drilling small pilot holes first and then go to a stepped style of drill bit to avoid cracking the rear casing.
9A0F139D-3358-46C8-A32A-9B2FEA088752.jpeg

I then used a round file to enlarge the holes to the exact size required.
D52D85EC-35F7-4A84-8343-685F1D69F151.jpeg

6. I used an RCA input panel from Jaycar Electronics. https://www.jaycar.com.au/2-way-phenolic-rca-socket/p/PS0263
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I had to trim around 6mm from each side to allow it to fit in the space allowed.

7. Bridge the ground terminals of both channels of the RCA inputs with wire/solder.
8. Cut 3 pieces of suitable gauge wire to around 10 inches in length each and then solder these wires to the Left and Right channel terminals of the RCA inputs. Next solder a third wire to create the earth.
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9. Place a little super glue on the RCA input panel before inserting them, together with the 3 attached wires from the front into the holes you've drilled in the rear case.
6E072622-9743-4D41-B3DA-6734420E7080.jpeg

Then JB Weld around the RCA panel to ensure a solid joint.
2200DECE-659A-4C48-972B-A896652F2472.jpeg

As you can see, with the decks out of the way, there is plenty of room allowing for easy access. The main board does not have to be removed during the mod.

10. Tin the ends of the 3 wires. Locate the 3 solder pads on the underside of the main board. (W301). The pads are very close together so you will need a fine tip soldering iron to make things easier. With pre-tinned wire tips, you should be able to simply hold the wire against the factory solder blob and apply heat for a clean solder joint.

a: The left most pad is your GROUND. (Black wire).
b: The next pad to the right is your RIGHT channel. (Blue wire)
c: The next one to the right is your LEFT channel. (Yellow wire)
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11. Ensure you have not bridged the connections whilst soldering. Test for continuity with a multi-meter. If the left and right channel solder pads are accidentally bridged, the 680 line in mod will only operate in mono!

12. Re-assemble in the reverse order.

13. Fire the Panny back up and select 'Tape' mode. Hook up your Iphone/MP3 player and you're away. The sensitivity of the tape circuit is ideal. I normally have the volume of my Iphone set to 1/2 to 2/3 volume for a volume similar to that offered by the CD player in this unit at a given volume setting. I've noticed no RF interference and no hiss at all whilst using the new Line In. :thumbsup:
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The function of the tape decks is completely unaffected by this mod. However, you will have to disconnect the RCA line in cables when playing a tape as leaving them connected will reduce the output level to the speakers.

Total time to complete the mod was around 1.5 hours. Centering, drilling and filing the holes for the RCA inputs is probably the most time consuming part of this mod.

Have fun and good luck with your own mod project.

James.... :-)
 

superlew

Member (SA)
Apr 22, 2012
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Looks good. :yes:
A successful Line-In Mod is very rewarding.
I did one on my Mom's DT600, using the Superduper method, through the tuner.
Being a 3-Piece, I used an unswitched 1/8" stereo jack, mounted in the back, and added a very discrete switch under the handle for switching between the tuner and the line-in.
I really should have taken pictures. :dunce: I'll have to do it the next time I'm in FL.
 

jimmyjimmy19702010

Member (SA)
May 5, 2012
3,578
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Sunny Brisbane, Australia
Sazeus said:
Thanks for the info!

This is one that I need to do. I don't see myself getting round to it in a hurry though.
I've been rocking the RX-DT680 like a wild man!! I had it at a BBQ on Friday night and it was a real hit. I had various party goers plugging in their MP3 players to the line in to play their favorite tunes! :cool:

James..... :-)
 

boomdon

Member (SA)
Jun 5, 2014
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0
:-)


Hey,
I recently did the line-in mod on my Panasonic RX-DT680 and it works with sound coming from both speakers and the balance control working switching from left to right.
One thing I noticed though is that the sound is not in stereo. Sounds like mono coming from each speaker. Followed the mod instructions to the letter.
Can I get some feedback on this ?
Shouldn't I be getting stereo sound with this mod ?
Don Warren
 

jimmyjimmy19702010

Member (SA)
May 5, 2012
3,578
26
38
Sunny Brisbane, Australia
boomdon said:
Hey,
I recently did the line-in mod on my Panasonic RX-DT680 and it works with sound coming from both speakers and the balance control working switching from left to right.
One thing I noticed though is that the sound is not in stereo. Sounds like mono coming from each speaker. Followed the mod instructions to the letter.
Can I get some feedback on this ?
Shouldn't I be getting stereo sound with this mod ?
Don Warren
Hi Don,

All 4 radios I have modded are all operating in stereo.

My guess would be a soldering issue where you may have a bridged left/right channel.
The pads a very close together on the circuit board. Check with a multi meter and get back to us. Do you have any pics of your mod?
 

boomdon

Member (SA)
Jun 5, 2014
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0
Hey Jimmy,
Thanks a bunch for the speedy reply and the advice. Found out indeed the left and right channels were bridge soldered together.
Performed the fix and now I'm getting great sounding stereo out of the unit.
I tip my hat to you, sir !!
 

riker1068

Member (SA)
Jun 5, 2014
1,088
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FLORIDA Jacksonville
Curious. I was thinking of doing all of my radios with a 3.5mm port. Could I just tap into the line in rca/aux and drill in a port assembly for the 3.5mm Stereo Panel Mount
? In no particular proper language. As I am trying to explain my thought :-D

image 1 as entry view
3 5 panel jack.jpg

Image 2 as rear for wire hook up from line in.
3 5 panel jack rear .jpg

Curious if I can just hook up a jumper? Or would that create feedback?

Figure I'd ask before I try.
 

jimmyjimmy19702010

Member (SA)
May 5, 2012
3,578
26
38
Sunny Brisbane, Australia
riker1068 said:
Curious. I was thinking of doing all of my radios with a 3.5mm port. Could I just tap into the line in rca/aux and drill in a port assembly for the 3.5mm Stereo Panel Mount
? In no particular proper language. As I am trying to explain my thought :-D

image 1 as entry view
3 5 panel jack.jpg

Image 2 as rear for wire hook up from line in.
3 5 panel jack rear .jpg

Curious if I can just hook up a jumper? Or would that create feedback?

Figure I'd ask before I try.
There is no reason why you couldn't do exactly what you suggest. I used RCA inputs on this mod so I could use the same cables I use on all my other boxes.

Good luck,

James.... :-)
 

Upuaut

Member (SA)
May 18, 2015
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0
Thanks,James.
I am not very clever with my hands but it all worked smooth as butter. Even knowing the number of screws in each case helps a lot :) I will be using a FiiO x3 as a source, however, using the line-out produces a signal which is a bit too strong and tends to give some distortion. But the earphone jack gives a very delicate output especially once the internal amplifier's treble ans bass are set to zero, only using the Panasonic's amplifier with the lavish bass.

Thanks again and good luck !
 

rci3044

Member (SA)
Jan 10, 2016
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Idaho, USA
Love the mod provided here. It has effectively resurrected my 680. I found an RCA block that had a tab sticking out that would accept a screw. I used this to mount the RCA's to the back of the box instead of JB Weld!

I, too tried using the data CD to play through the RCA outs but I wasn't pleased with the sound. It just didn't seem full enough. I am extremely pleased with the sound quality using this line-in RCA mod.
 

jimmyjimmy19702010

Member (SA)
May 5, 2012
3,578
26
38
Sunny Brisbane, Australia
rci3044 said:
Love the mod provided here. It has effectively resurrected my 680. I found an RCA block that had a tab sticking out that would accept a screw. I used this to mount the RCA's to the back of the box instead of JB Weld!

I, too tried using the data CD to play through the RCA outs but I wasn't pleased with the sound. It just didn't seem full enough. I am extremely pleased with the sound quality using this line-in RCA mod.
Nicely done rci3044! I've lost count how many people have now successfully added a line in to their RX-DT680s - certainly a lot more than have posted in this thread.

We've got to do all we can to keep these awesome 680s thumping deep into this century!

James....':-)