This is not an "antique" radio question, but I'm hoping that one of you radio pros might be able to help me anyway.

I have a Panasonic RX-DT690 all-in-one "Portable Stereo Component CD System" (CD/AM/FM/2 cassettes). Its about 9 years old now, but still a great unit with excellent sound. I would like to connect the output of my MP3 player to it, but there's a problem- it doesn't have an external line input. It does have a microphone input, which works OK, but the darned thing is a monaural input (it sends the left input to both channels. No, it's apparently not a bad microphone jack- it's designed that way). That's OK for old Benny Goodman recordings, but anything more recent requires a left and right input.

The solution is to hack the circuitry and add a line/auxilliary input, perhaps using switch selection between the tape decks (which I never use) and an external connector. So my question is, can anyone supply me with a schematic for this unit? I don't need a complete manual. All I really need is the schematic so I can pick the best place to insert the signals.

By the way, I'm aware of those devices that can play an external source into the cassette deck. They just don't work well in my machine, and even if they did, I don't want the cassette motor running continuously. I could also use one of the many FM transmitters available, but they don't have the cleanest of signals, and I would rather not transmit everything to the neighbors.

So I'm stuck with adding an auxilliary input. Any help with a schematic would be appreciated.

Thanks.

Isn't that just the way it goes.
My Panasonic Ghetto Blaster manuals end at RX-DT680. I wonder how different the 680 and the 690 are? The 690 is probably either the next one in that model line, or the 680's replacement in the next model year, or even the US version of the Canadian 680.
Anyway, I've been selling my portable audio, VCR, and TV/VCR combo manuals for $2.00us + postage. If you get stuck finding a 690 schematic maybe the 680 is close enough in circuit design to accomplish what you want to do. Often the differences in models close to each other is purely cosmetic.
I did a quick google for your model and didn't find anything to promising but a lengthy search might turn up something.
Good luck
Jim C.

Jim-
Thanks for the offer. I have the -680 schematic already, and it seems to be at least a little different than my -690. I have been hoping to get a diagram that I know is 100% accurate, but as you said, the other one might be good enough to steer me in the right direction.

I've got exactly the same Panasonic boombox: I like it, but no way to plug a MP3, computer or LP player in!

One year later... Did you manage to fix your problem ?

I've downloaded the 680's schematics, but I'm unable to do anything with them all by myself: maybe you could give me a hint?

Thanks,
Frederic
(Sorry for my poor English writing)

Frederick,

Yes, I managed to modify my 690, and everything works well, including the added "auxilliary inputs". Check your Personal Message box.

I have a RX-DT690 and would like to add an aux input as well. Can you guys tell me how you went about doing this.

Thanks

Send me your email address via PM or email, and I'll send the instructions to you (250KB pdf file).

Update:
The link to download the instructions for this modification is at
http://www.mediafire.com/?clymytnyymd
Please don't ask me to send the file to you, just go to that site and download it for yourself.

Hey Guys I have got the same problem and need to add an aux input to my RX-DT680 radio as well and I was wondering if you could help me. I noticed ALLTARE you mentioned 690 but I wouldnt think there would be much difference between 690 and 680.

Thanks

Nope, not much difference as far as this mod is concerned. Frederic, above, says the mod works OK for his 680. Send me your email address via Personal Message, and I'll send the instructions to you (~350KB pdf file- it keeps growing).

Update:
The link to download the instructions for this modification is at
http://www.mediafire.com/?clymytnyymd
Please don't ask me to send the file to you, just go to that site and download it for yourself.

Hello,
Can you please send me the instructions for adding an aux to the 680

Thanks
lzk

I received your PM, but you didn't give your email address. PM it to me and I'll send the info.

Update:
The link to download the instructions for this modification is at
http://www.mediafire.com/?clymytnyymd
Please don't ask me to send the file to you, just go to that site and download it for yourself.

I also have a RX-DT690. I found this thread via Google and don't know if my other request is in the correct area.
My first request has to do with receiving the instructions for adding an aux input to my RX-DT680 radio. I hadn't used it for at least 4 years and finally unpacked it after moving sometime ago and recently began using it again about 3 weeks ago.
I forgot how good the sound is, particularly the bass and was thrilled that I found a thread that can accomplish this. I will PM to get the instructions as I've read on the other posts.

My second request is that unfortunately after about 2 weeks of using it, the CD player has several problems.

1. Sometimes when I push the Play button it won't play and I can see the CD spinning.

2. Sometimes it will play but stops when it gets to Track 2.

3. Sometimes it will play a little past Track 2 but will start Fast-Forwarding and then stop after about 1 min or so while still showing Track 1. I've tried hitting Play or Fast-Forward to help it along but it didn't work.

4. The CD compartment gets VERY hot. Not sure if this is normal for the player. I do seem to remember it normally being hot, but not sure if it was this hot.

Can this be repaired easily by most anyone, or is this going to be a major undertaking because of the age and type of device it is?

I almost forgot to mention that I haven't used a lens cleaner since unpacking it because I've heard from various sources that they ruin the lens. I used to use one in the past quite regularly. The type I used was the kind with the brush attached to the CD.

What is the best way to clean this type of lens?

It sounds like your CD player is failing- mine only gets slightly warm. My attitude would be to not worry about it- If you remove some of the CD-playing hardware, you'll be left with a nice little compartment that's perfect for stashing your mp3 player, if it's small enough, while it plays into your new input connectors. Since I did the modification, I have never seen the need to play ordinary CDs. I have ripped all of my CDs to mp3 files, and they're all on the ipod now.

On my other CD/DVD players, the only "cleaning" I've done is with a can of compressed air, so I can't say anything about your brush. However, since your player is out of commission anyway, it can't hurt to try various cleaning methods.

Check your email for the modification instructions.

When I first started this thread, I was simply looking for schematics, but since I completed the project I have been offering how-to-do-it instructions to anyone else who wants them. I expected that there might be 3 or 4 interested parties, but instead, there have been several dozen.

To make life easier for me, and to save everyone from the bother of having to contact me for emailed instructions, I have now posted them online on MediaFire. For free download, go here: http://www.mediafire.com/?clymytnyymd .

If I sent you the instructions before March 15, 2008, you may want to take a look at this updated file. Note- the file size has now risen to about 450KB.

Alltare

PS- I'm still looking for schematics for the RX-DT690

Hey guys, thanks for the helpful tips on making a line input for the Panasonic RX-DT680/690. I just picked up the 680 at the thrift store. Took a gamble because there was no power cord present to test at the store. I came with the remote though. It's a great sounding boom box. Now the conflict of the Line Input. I used the first example to make the line in, but I did not use a toggle switch, and I used a 1/8th inch stereo input I ripped off an old broken CD-ROM drive, it served as the headphone input to the CD drive. I got everything working fine. No noise or hum. Great! And through the process, am now intimate with the machine. I used my $1 solder iron to do the whole project and used it to punch a hole in the back wall to run an extra long cable with the 1/8th inch input on the end. Like a snake, instead of 'fixing' it to the boom box. Suits my needs. I'll post pictures here in the message..just scroll down if you don't see them. So far so good. I have the input fed from my GLI mixer, which mixes 2 Phono inputs for turntables, and AUX input from my computer, and another AUX from TV, and then TAPE from my tape deck. When I play i through the Panasonic, I have to keep the volume very Low, like at 1 or less to keep from distorting. It seems to be running through and peaking at a low Attenuation. Not a problem really, but I wonder why this is? And when I play a MONO record through, it is garbled noisy, but somehow relevant audio information on the right speaker, and the left is clear and full range. I'm wondering if I missed doing something when hooking up the Jack i took from the CD-R, to run two similar channels (ie. MONO) through stereo..I'm afraid somehow with mono, they go out of phase. IF anyone can help me rectify that.. But stereo is fine. Yep..so this is a superb boom box..and the CD MASH algorhythm is lush, the tape deck very solid (but will need new belts soon, I have to ff..rew a couple times at first to get the rubber to stick, at first i thought the belts were done for..but both work for now) Thanks again for posting details!!!

I ended up just trashing the 1/8th" mini jack because I could not figure out why it was dropping out the Right side when playing a dual Mono source. I tried different wiring combo's, but nothing helped. I could make it total Mono, or Stereo, but not both. Weird. I guess I don't understand how to wire the mini jack? So i just spliced the wire, and took a RCA Female stereo plug and adapted it. Now everything works great. No longer as sensitive, i can turn the volume up without the weird distortion i was getting before after only 1 o' clock and Stereo and MONO sources work crystal clearly.

Now for the next question..anyone know why only the CD is transferred to the output RCA jacks, and not the Tape and Radio functions? This might be possible?

scottsasonic-

I'm glad everything finally worked out OK. Your idea of using the 1/8" jack is certainly valid. I suspect that you were somehow getting the left and right hot audio signals connected to the shield/ground conductors, but that's just a guess. Or maybe it was just an oddball jack.

As for the output jacks, who knows why they're only for the CD deck. For that matter, why does the microphone jack only feed the left channel (of a stereo mic) to the amplifiers? Maybe they sold a 'deluxe' model that didn't have these glitches.

If you don't mind telling us, how much did you have to spend for your 680? It seems to me that I paid about $300 for my 690 when new.

alltare
===================================

I have a bunch of stuff on audio tapes that I would like to digitize, but unfortunately the tape deck my stereo no longer works. When I put in a tape, it recognizes that there is a tape inserted, and if I press play it sounds like the motor starts, but then it pretty much immediately stops.

I am wondering if there is a malfunction due to a tension sensor so that for some reason the unit thinks it is pulling too hard and has reached the end of the tape?

I don't see anything that I can clean.

I really like this stereo and I hate to destroy it trying to fix the tape deck, but if anyone has any thoughts, I would greatly appreciate it.

Cheers!
-T

tater, if you open it up I'm sure you will see that the belts have turned to goo. They will need replacement as well as replacing/resurfacing any clutch assemblies. Usually the pinch rollers will still be good IF they haven't hardened on you.

alltare, Thanks for the PDF with the modification. I have the RX-DT680 and it's been a great unit. I sure would love a line level out put on it though.

Right now I'm working through a problem with it. I think the transformer died. I can only get a very small amount of sound out of the tweaters. No sound out of the woofers at all. Hopefully I'll get it fixed.

I haven't found a free download of the schematic or service manual for the 690 but I did find a rather cheap download.

http://eshop-manuals.com/product_info.p ... s_id/72954

I like the 1/8th" stereo jack mod removing the need for the separate switch.