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RC-MJ70 Line In DIN question

RC-MJ70 Line In DIN

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#1 EX_m71_Owner

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Posted 10 April 2016 - 11:07 AM

Hello,

 

my unit is a European one and does not have the Cinch Line In connector as the american model but a DIN connector for Line In. This is for a 5 pin  DIN plug. I do have adapters with DIN Plug and on other end Cinch (which is 4 Cinch connectors =  Left +/- and Right +/- .

 

The problem is, when I connect it via DIN with an external source like an Ipod etc. and then  switch source at RC M70 to Line IN, it does not work. Waht I have to do is set the Tape on Record (with or without PAUSE) and then I get the external signal played via the RC M70.

 

In other posts I have read that there is no such a problem with American models. But I am not sure if this is a problem generally for models with DIN connector or just a problem of my unit.

Maybe someone can tell me.

 

 



#2 BoomboxLover48

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Posted 11 April 2016 - 06:08 AM

Klaus,

 

Please post pictures showing the line in and all for this version of M70. I don't think many of us are familiar with this version of M70.



#3 caution

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Posted 11 April 2016 - 10:22 AM

I own a M70L

You have to press down record if you want to use the line-in, that's how it was designed to work.



#4 EX_m71_Owner

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Posted 12 April 2016 - 01:37 AM

Hi,

 

Here is a picture of the DIN connector at the unit (called REC..)  and also the adaptor for Cinch I use. the white and red Cinch are for playing while Yellow and Black would be used for recording on an external unit (Line Out).

 

The color change in the picture at the DIN connector of the M-70 looks strange, that is why I did change the picture (brightness of that area) so the 5 connectors of the DIN can be seen better.

 

So I understand that it is regular that you have to press RECORD at European units in order to hear the Line In Signal. I think an electronic specialist should be able to make that work that setting the Source switch to LIne-In would automatically switch the other contact so pressing REC is not necessary anymore.

Attached Files



#5 jimmyjimmy19702010

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Posted 12 April 2016 - 01:47 AM

The 5 Din inputs I've seen always seem to play a lot quieter than the RCA version. A local member had a euro spec M90 with a 5 din input - it was virtually unusable with an MP3 player as the sound level was so low even with the MP3 players volume set to max.

#6 EX_m71_Owner

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Posted 12 April 2016 - 02:12 AM

Hi Jimmy,

 

that is funny - at my unit it is just the other way. I have to set the volume to almost minimum at eg my phone or Ipod. If I have a normal level there and the volume at the M70 is set to very low, it is already loud as hell (but not nicely loud, very distorted, too much input signal. Maybe it also depends on the adaptoers which are used. ? Basically something is strange with the DIN connection of the M70. I thinkt the signals there are not identic with the ones with the Cinch Line In.



#7 Helmar

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Posted 12 April 2016 - 02:51 AM

Hi Jimmy,

 

that is funny - at my unit it is just the other way. I have to set the volume to almost minimum at eg my phone or Ipod. If I have a normal level there and the volume at the M70 is set to very low, it is already loud as hell (but not nicely loud, very distorted, too much input signal. Maybe it also depends on the adaptoers which are used. ? Basically something is strange with the DIN connection of the M70. I thinkt the signals there are not identic with the ones with the Cinch Line In.

If it is too loud and distorted the signal probably goes through the internal phono pre-amplifier.

see

https://de.wikipedia...iki/DIN-Stecker

Read the german version, only there the differences between phono and line-in are explained.

Gruß

Helmar



#8 BoomboxLover48

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Posted 12 April 2016 - 06:54 AM

Hi Klaus,

 

   Try to get this unit which is another option.  I can see a phono RCA plug in your pic.

 



#9 caution

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Posted 12 April 2016 - 10:12 AM

You could modify the RCA jacks so it behaves like a JW model, wouldn't be impossible.



#10 BoomboxLover48

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Posted 12 April 2016 - 11:21 AM

For phono I believe there is a pre amp circuit and one can bypass and use it as a normal line in right?



#11 caution

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Posted 12 April 2016 - 12:11 PM

Yes, but L models seem to expect a line-in signal with different characteristics. Its schematic shows other differences to the JW model that I could not understand well enough to modify it. There are additional parts, perhaps an LC filter in there, and so on, so I left it alone.



#12 EX_m71_Owner

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Posted 14 April 2016 - 03:22 AM

Yes, but L models seem to expect a line-in signal with different characteristics. Its schematic shows other differences to the JW model that I could not understand well enough to modify it. There are additional parts, perhaps an LC filter in there, and so on, so I left it alone.

Caution - I was also thinking of Boomboxlover's proposal. I wanted to show that to a tech/electronical specialist who can read (and understand) the circuit schematic plans - to bypass the phono preamp section and by that turning it into a regular Line In. Your last post alerted me  and said loudely "CAUTION"  (and I do not mean your name ;-) ). What you say is, that the circuits and components of my model are different to the US model. I have the Service manual for the US model and that means that its schematics are actually "wrong" and not showing what is really deployed in my system - so I would maybe get the specialist on a wrong track. Where is your knowledge from of the fact, that the schematics of the JW model are different to the US model? Does it mean there is a different service manual specially for JW models, and if so, do you happen to have that maybe?



#13 caution

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Posted 15 April 2016 - 10:58 AM

Yes, like I already said, the JW and L versions are very different on the front end audio circuits.

 

Save the following two images and view them in full-screen mode, fit to the screen. Then flip back and forth between them. They are the amplifier schematic pages from the L and JW models. Notice all of the differences. There are just too many to bother with.

 

26419995796_69bf02c9a5_o.jpg

26173081550_f0aeb690c8_o.jpg



#14 EX_m71_Owner

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Posted 16 April 2016 - 03:21 AM

Thank you for the information Caution. So there are different service manuals around obviousely. Good to know.



#15 Hisrudeness

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Posted 16 April 2016 - 02:55 PM

To be honest it would be way easier to use an attenuator. Pretty much any L or LB model will sound much better and smoother with one of these.
I use a couple of these for at least 7 euro spec boxes including an M90 and they work very well.

#16 goodman

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Posted 17 April 2016 - 01:13 AM

The same problem is solved with phono / line adapter:

https://boomboxery.c...ine-in-problem/

 

dsc07431.jpg



#17 goodman

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Posted 17 April 2016 - 02:06 AM

if you understand a bit of electronics you can make a similar mod:
- install 3.5mm jack near the din jack.
- use this scheme with 10 k ohms resistors to adjust input levels.

 

Attached File  line in mod.jpg   103.63K   107 downloads

 

 



#18 EX_m71_Owner

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Posted 17 April 2016 - 07:38 AM

HisRudeness:

Thank you .  When you speak of an attenuator (I had to check in internet what that is , now I know I guess). It is described as a unit that reduces incoming power so the signal coming to the unit "at the end" is weaker than the original power received by the attenuator. So if you look at Goodman's proposal with the 3.5 jack, that is actually an attenuator, right? So I guess a line IN to Phono adpater is also more or less also an attenuator. ? 

 

 

Goodman:

 

Thank you for the schematics with 3.5 Jack. By doing this you would not even need any adapter (Cinch/3.5) resp a Line In to phono changer.

that means (as said above to HisRudeness) that the 3.5 jack solution is actually the same (technically) as the Line In to Phono unit, right, you could say a built in Line In to Phono adaptor.

I am not a specialist but I understand a bit of it to say it in your words. Do you confirm that I can also do my next proposal of which I think that it is actually just the same as your solution, or better a variation of it:

I just take a regular cable with a 3.5 plug (for MP3 unit)  on one , and 2 Cinch plugs at the other end. Then I cut the cable and apply the 2 10k Ohm resistors in between. That should be the same as yours with the built in jack, right?

By doing it that way I would not change anything inside the unit and keep it original. That is why I came to this idea.



#19 goodman

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Posted 17 April 2016 - 09:49 AM

 

I am not a specialist but I understand a bit of it to say it in your words. Do you confirm that I can also do my next proposal of which I think that it is actually just the same as your solution, or better a variation of it:

I just take a regular cable with a 3.5 plug (for MP3 unit)  on one , and 2 Cinch plugs at the other end. Then I cut the cable and apply the 2 10k Ohm resistors in between. That should be the same as yours with the built in jack, right?

 

This is impracticable and I think would not work...

This is an attempt to do attenuator,

but he does not only consist of 2 resistors...

Attenuator is specifically designed scheme.

Therefore, it is placed in such a case.

 

My Idea is to bypassing the phono amp.

In this case, you must open the radio, drill hole for 3.5mm jack,

find 8 pin connector, with a soldering gun making electrical connections.

 

 

If you don't want to open the radio and keep it in its original form,

you must buy attenuator, just like this:

41tdwy9O6WL._SX300_.jpg



#20 caution

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Posted 17 April 2016 - 10:54 AM

I noticed that the aux input on my C-100F uses the same op amp, but it has a switch that allows you to toggle between line-in and phono on the same RCA jacks.

 

Instead of just using a 10k in series for line-in, they used a voltage divider setup with a 39K in series with a 6.8K to ground, which is probably a little better. When all positions for switch S102 are toward the op amps, it's in phono mode. When they are positioned away, it connects to the resistor divider networks for line-in mode. The part values are all slightly different but accomplish the same task.

 

If you don't want to add another jack, you could just convert the phono to be line-in instead :-) Or add a switch and have both :-)

 

26392356112_8bd1285820_o.jpg

 

26484656935_b9836de58d_o.jpg



#21 EX_m71_Owner

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Posted 18 April 2016 - 11:24 AM

My Idea is to bypassing the phono amp.
In this case, you must open the radio, drill hole for 3.5mm jack,
find 8 pin connector, with a soldering gun making electrical connections.

Ah, now I see. With your first reply I did not understand because I thought my variation was just the same  as yours. But what you added in the meantime about bypassing made clear that it is absolutely not the same. You see, I am not a specialist in reading schematics. My fault was, that I thought that the way of the signal from the DIN would be the same as the way from your new 3.5 jack. The reason for my mistake was that I just did not see the DIN plug anywhere in this schematics. I think I have found it now. I actually thought that it is the location shown below before, but I thought it was not this one,because there are 6 contacts and the DIN socket has only 5. Why is that? Am I right with the location of the DIN socket? See Pic:

Attached Files



#22 EX_m71_Owner

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Posted 18 April 2016 - 11:44 AM

I noticed that the aux input on my C-100F uses the same op amp, but it has a switch that allows you to toggle between line-in and phono on the same RCA jacks.

 

Instead of just using a 10k in series for line-in, they used a voltage divider setup with a 39K in series with a 6.8K to ground, which is probably a little better. When all positions for switch S102 are toward the op amps, it's in phono mode. When they are positioned away, it connects to the resistor divider networks for line-in mode. The part values are all slightly different but accomplish the same task.

 

If you don't want to add another jack, you could just convert the phono to be line-in instead :-) Or add a switch and have both :-)

Thank you Caution , even though I do real changes in the unit, they are only inside and can not be seen (without switch). And the times when I needed to really connect to a turntable for recording are long gone. The phono line is probably not used by many people generally .



#23 goodman

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Posted 18 April 2016 - 01:19 PM

Look carefully next picture.
On the top in purple color is DIN socket.
In blue color is DIN amplifier.
Signal from DIN socket go to DIN amp and go to recording head.
You dont need to do anything here.
In green is chinch for PHONO IN.
In red is PHONO amplifier.
Signal from PHONO chinch go to PHONO amp and conected to MODE SWITCH (3 yellow lines)

My idea is bypasiing Phono amp, and conect 3.5 mm jack to this 3 yellow lines

 - this is the 8 pin conector - you need pin 6, 7, 8. (see my previous picture)
When MODE switch is on PHONO position,
signal from 3.5 mm jack go direct to FINAL JVC amplifier.

 

 

Attached File  din and phono.jpg   149.63K   30 downloads

 

picture of din and phono plate.

In red is 8 pin connector - you need pin 6, 7, 8.

 

Attached File  din and phono plate.jpg   109.47K   43 downloads



#24 EX_m71_Owner

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Posted 19 April 2016 - 07:00 AM

Thank you Goodman - and Caution

I should have had a closer look at Cautions 2 pictures (or the JW manual resp), but once I had seen the pictures made by Goodman (with the external jack) I only looked at this further. So I did not see the DIN socket of course because it was not on there.

 

Well , you both will probably think, if I really will do that change, that will turn out in a desaster :blush: and my M70 will  :angelic:  , because I am obviousely not that what you would call an electronic specialist. But when I will be up to it I will have an electronic pro with me. I just wanted to understand as well and by that also learn something . And you helped me a lot - THANK YOU.

 

I will post, when I will do it. Before I will try to clean contacts of the unit, because I have a lot of problems especially with the SOurce switch. I have to "play" with it again and again everytime I change source until I can hear correct volume and both channels. When this is done I will do start with the modification.



#25 goodman

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Posted 19 April 2016 - 11:34 PM

Thanks for the kind words. I'm glad that I helped you.
I waiting for information and photos of the modification process.

 

PS:

I think, that you won't use phono and din connectors,
and won't make modification on phono board.
In this case, must disconnect 8 pin jack from phono board.
This is easy way to stop 12 v to phono amp (pin 5).

This is important step!!!

 

Connect 3.5 mm jack with resistors to this 8 pin connector. You need pin 6, 7, 8.

I agree with member caution about resistors. 10 kohm is min. value.
Adjust of sound level depends of type music, mp3 player volume, and this resistors.
You must test first with 33 k ohm, and low volume of MP3 player.

If sound level is low you can use 20 K ohms or 10 K ohms.



#26 goodman

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Posted 27 January 2017 - 04:38 AM

Is there any progress with this mod?



#27 Dancorp

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Posted 13 December 2017 - 01:13 PM

I just bought a JVC M70L that I am waiting to receive.
I would like to integrate a Bluetooth module... so a line-in is mandatory.
Any progress / tests to share ?
 
Does the DIN connector have a output line too ?

PB seems to mean PlayBack, like a kind of Line Out?.



#28 goodman

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Posted 17 December 2017 - 04:32 AM

JVC_RC-_MJ70_Line_In_DIN_-_04.jpg

Find a 8 pin jack.
Solder violet cable to ground (7).
Cut the cables for L (8) and R (6) channels at 4-5 cm before jack.
Solder 8a to 3 (L channel).
Solder 8b to 1 (L channel).
Solder 6a to 4 (R Channel).
Solder 6b to 2 (R Channel).

PHONO IN  - work as before modification.
LINE IN - use 3.5 mm jack for line in, phono input is disconnected.

BT module line out must be connect to 3.5 mm line in jack.

You need power supply to BT module too.

This is on theory.

I don't have this box to made this mod.



#29 Dancorp

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Posted 17 December 2017 - 05:56 AM

Goddamn it! You made my day !
Thanks a lot for your study
I would try that when i will receive the box.


#30 Dancorp

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Posted 21 December 2017 - 05:39 PM

Where's Wally?

https://photos.app.g...oGZBz1Zvyfakcu1

 

The easiest way would be to have the M70L service manual..

Someone to share it pls ?





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