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How do you add a line in to a Helix-4636?


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#1 Smeats

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Posted 27 February 2015 - 03:08 PM

Hi, I can't even find a schematic for a Helix-4636 aka WATSON RR 5600 so that would be a start! Where would you wire your new RCA input socket to?

 

I am sick of this lovely looking box just sitting on a shelf in my garage looking all pretty but never getting used and I know I could use a FM trasmitter or cassette adapter but if someone would be kind enough to take the time to answer this, I would be very very grateful and get right on it immediately :yes:


 

 

 

Attached File  helix.jpg   75.05K   7 downloads



#2 JVC Floyd

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Posted 27 February 2015 - 03:20 PM

if it has external mic inputs you can wire the rca cables straight to the board after removing the mic sockets.



#3 Smeats

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Posted 27 February 2015 - 07:29 PM

Thanks dude! I've bought the RCA sockets now and will check that option out this weekend!



#4 goodman

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Posted 28 February 2015 - 02:40 AM

Maybe you must find where radio board

is connected to main board - radio line out.

See this topics:

http://boomboxery.co.../?hl= line mod

 



#5 Smeats

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Posted 28 February 2015 - 05:44 AM

lots of good advice there, thanks Goodman!



#6 Smeats

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Posted 28 February 2015 - 10:50 AM

if it has external mic inputs you can wire the rca cables straight to the board after removing the mic sockets.

Just looked inside and it has a built in mic! Is it Just a matter of unsoldering the 2 wires from that (leaving the other ends attached to the PCB) then solder them to the new RCA sockets and running a wire from the new sockets to ground?



#7 Cpl-Chronic

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Posted 28 February 2015 - 01:44 PM

En  MIc inputs are much more sensitive than a proper LINE IN circuit.  It wouldn't work very well & your imput would be saturated.



#8 Smeats

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Posted 28 February 2015 - 03:14 PM

En  MIc inputs are much more sensitive than a proper LINE IN circuit.  It wouldn't work very well & your imput would be saturated.

thanks cpl! had a feeling it wasn't going to be that simple,

I wanted to find where the radio input +ve and -ve goes as it should be at the correct signal leval for an mp3 player but without any diagrams it's not obvious!



#9 JVC Floyd

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Posted 28 February 2015 - 03:32 PM

you need a dedicated mic input jack for my idea to work, i did this one my trident cx43f and it works great but it has external mic input jacks.



#10 Superduper

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Posted 28 February 2015 - 05:28 PM

Just looked inside and it has a built in mic! Is it Just a matter of unsoldering the 2 wires from that (leaving the other ends attached to the PCB) then solder them to the new RCA sockets and running a wire from the new sockets to ground?

Lets put it this way, mic inputs run about 2mv while Line inputs range from 150mv to 1.5v(1,500mv).



#11 Smeats

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Posted 28 February 2015 - 10:40 PM

Lets put it this way, mic inputs run about 2mv while Line inputs range from 150mv to 1.5v(1,500mv).

Just read your pinned thread on line in Super Duper! Tape, radio and mic can all have different signal levals and can all have their own pre amp circuit!!  Sounds like a  total mine field for damage if you don't know what you are doing.  I am now unsure how or if to proceed with this little project! :



#12 Superduper

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Posted 28 February 2015 - 11:42 PM

If  you are able to do some sherlock holmes with a digital meter, you will find that the function switch is the best place to tap into.  That's because all the signal levels are pretty much equalized at that point so line-levels are an appropriate signal to inject at that location.  The function selector is a multi-pole switch that switches the various functions (tape, aux, phono, radio) and pipes it to the preamp for processing.  You won't want to tap into the radio circuit since that will interfere/confilct with radio audio.  However, it is possible to pipe it into the phono function since presumably, you don't have a phono hooked up and at that point, the signals would have already been boosted to the proper signal level.  However, if you don't have a phono function and only have tape/radio, then that's more problematic since tape function usually requires the deck to function to turn on the amp.

 

However..........  somewhere in the archives, I did do a line-in add mod for a Wards 3996 Airline, and that basically took the radio signals and put them through a switched 1/8" phono jack.  Normally radio would work fine with nothing connected to the jack.  When a 1/8" plug in inserted into the jack, it switches out the radio signals and instead, takes the signal from the aux jack.  Perhaps that's the easiest way to do it for you.



#13 Cpl-Chronic

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Posted 01 March 2015 - 02:56 AM

Conceptually, I would try to tap into some location on the pre-amp stage, somewhere forward of the tone controls so that you can still adjust volume, bass, treble, etc. & then amplified by the main AMP IC's or transistors.......

 

Tap into that location with your RCA wires & use the right type of switch, maybe a 3 pole switch, to turn that home-made splice on & off....

 

Basically the signal input at the preamp stage would have 3 conductors, Gnd(-), L(+), R(+) just like a mini-stereo plug has a common(-), L(+), R(+) connection. 

 

Super can correct me if I have that wrong but from my limited knowledge, I think that's how it breaks down as far as raw connections.  You just have to find out where those points are on the preamp board/stage & tap in....right?



#14 goodman

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Posted 01 March 2015 - 06:33 AM

Smeats, please make a some good pictures of inside the boombox.

To see boards and to give you advice. :yes:



#15 Smeats

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Posted 01 March 2015 - 07:02 AM

Smeats, please make a some good pictures of inside the boombox.

To see boards and to give you advice. :yes:

I promised rokbox2112 some pics of the inside to help him out, so I'll get on that today!

 

thanks



#16 Smeats

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Posted 01 March 2015 - 07:27 AM

If  you are able to do some sherlock holmes with a digital meter, you will find that the function switch is the best place to tap into.  That's because all the signal levels are pretty much equalized at that point so line-levels are an appropriate signal to inject at that location.  The function selector is a multi-pole switch that switches the various functions (tape, aux, phono, radio) and pipes it to the preamp for processing.  You won't want to tap into the radio circuit since that will interfere/confilct with radio audio.  However, it is possible to pipe it into the phono function since presumably, you don't have a phono hooked up and at that point, the signals would have already been boosted to the proper signal level.  However, if you don't have a phono function and only have tape/radio, then that's more problematic since tape function usually requires the deck to function to turn on the amp.

 

However..........  somewhere in the archives, I did do a line-in add mod for a Wards 3996 Airline, and that basically took the radio signals and put them through a switched 1/8" phono jack.  Normally radio would work fine with nothing connected to the jack.  When a 1/8" plug in inserted into the jack, it switches out the radio signals and instead, takes the signal from the aux jack.  Perhaps that's the easiest way to do it for you.

Hi Superduper, found the thread with your mod and it looks like it would be the best solution, where can I find a switched phono jack, tried searching but no luck so far :hmmm:



#17 Smeats

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Posted 01 March 2015 - 10:31 AM



Smeats, please make a some good pictures of inside the boombox.

To see boards and to give you advice. :yes:

Here is a pic of the main PCB, all the radio circuitry is on the right, tape in the centre and amp on the right

 

Attached File  2015-03-01 13.57.29.jpg   104.7K   6 downloads

 

on the opposite side there are 3 wire going from the radio part of the pcb to another pcb for the 5 band balance equalizer controls, left and right channels (orange an white) and the grey is ground I think!

 

Attached File  2015-03-01 13.59.57.jpg   112.82K   6 downloads

 

 

Here is the wires connected at the equalizer pcb closer up

 

 

 

Attached File  2015-03-01 14.00.46.jpg   77.79K   4 downloads

 

 

I think this is where I should put my line in to but please correct me if I'm wrong! :-)



#18 goodman

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Posted 01 March 2015 - 12:16 PM

Smeats, thanks for pictures.

On last 2 pictures you show connection from main board to LED METER.

This isn't place to connect anything!!!

2015_03_01_13_59_57.jpg

 

2015_03_01_13_57_29.jpg

 

This Is my vision about boards:

Radio and main is on one big board. Not easy to find radio out ...

Is it possible to connect line in on tape head in jack, but sound will be distorted....

Wait for advice from other members, before do anything wrong...



#19 Smeats

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Posted 01 March 2015 - 10:30 PM

Looks like I was way wrong!  :dunce:  thanks for your detailed explanation goodman, I will take you advice and hold on for now!



#20 Reli

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Posted 02 March 2015 - 02:35 AM

Wow, all that stuff mounted to one HORIZONTAL board.  I hope there's some kind of ledge that helps support it on the rear case.



#21 Superduper

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Posted 02 March 2015 - 01:09 PM

I'm going to just flat out say it....  there is NO WAY that anybody, anywhere, anyplace, can look a a photo of a boombox circuit board, and tell you which pad to connect to, which wire to cut/splice, which trace to cut.  It would be hard enough to look at a blowup of a schematic diagram, but just looking at a photo, it would be impossible.  The exception is that IF someone were to have that exact same boombox in front of them, figure it out, and then post a closeup to you of how it's done.  Other than that, YOU would have to have enough technical expertise and skills to be able to figure out where to tie in.  That's because EVERY SINGLE MODEL or variant of that model is going to be different.  There is no modular system or interface like you would expect when assembling a modern computer.  And although one can sometimes "presume" that red=pos and black=neg/ground, it is by no way guaranteed, and beyond +/-, there simply is no standard wiring convention to go by for any other wire connection.  Also black neg is different than black ground.  Giiven this, the only way to do a mod like this is to test and trace to find the audio signals.  That is a hands on process and not a look at a photo of one side of a board and tell you what to do type of thing.

 

On my Wards retrofit, that refit, if done exactly like that, would only work for that particular model.  While it could technically work on virtually any model, the exact method of where to splice into the radio signals varies depending upon the model.  I showed it not to suggest that you do it exactly like that on any other boombox, rather it was to demonstrate the overall process you would employ and while a similar mod could be employed on say, a sanyo boombox, you would still need to customize the install and retrofit, and this means first finding out the exact audio signal path.

 

On your particular boombox, here are 2 possible methods  I would approach it:

 

1.  First, find the MPX decoder chip.  It would usually be one of the IC's on the tuner board.  Look up the datasheet and find the audio L/R output signals pins.  Follow those traces (through caps and resistors if necessary) until it terminates at the function selectors.  That would usually be where it would be tapped.  However, it MUST be confirmed by way of an audio signal tracer.  Cut these traces and they would be where you would splce into.  On some models with a separate tuner board, this is much easier since the audio signal lines would be tethered by wires and they are easier to find.

 

2.  I found a larger image online where I could see the buttons.  You have No AUX, No Phono.  Howver, you DO have a power button.  That is good because on many boomboxes, the function selector on tape setting shuts the boombox down.  It looks like it is possible to power on the boombox on the tape setting using only the power switch.  If that is the case, then you just need to find the audio signal pins of that tape switch.  The simplest way is to use an audio signal generator, and probe the pins from behind the switch.  I'm not going to go into a whole classroom lecture on how to do that.  But that is how I would approach it.  This is the simpler of the two methods since it requires no switching jack, just a standard stereo 1/8" jack (or even RCA's) and tap into the correct side of the tape switch.  Obviously, you should not have anything connected to the new aux connections when a tape is playing and make sure to use shielded cables.



#22 Smeats

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Posted 02 March 2015 - 02:09 PM

I really appreciate all of your time and input everyone and you are a wealth of knowledge Superduper! I was kinda banking on this being a (semi) simple job and I have to admit I'm........

 

Attached File  iomy.jpg   20.48K   9 downloads



#23 JVC Floyd

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Posted 02 March 2015 - 02:34 PM

i would just make some tapes to listen too on it .



#24 Reli

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Posted 02 March 2015 - 04:30 PM

Have you tried just turning your iPod down to its minimum volume setting?  That's what I've done on a couple of my boxes that only have Mic inputs, and it works fairly well.  You might have to press Play or Rec/Play, but if it has a Remote jack, you can stick a plug in there and it will short the tape motor so that it doesn't run.



#25 hemiguy2006

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Posted 02 March 2015 - 05:44 PM

this radio doesnt even have a phono input????



#26 Smeats

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Posted 03 March 2015 - 11:58 AM

Have you tried just turning your iPod down to its minimum volume setting?  That's what I've done on a couple of my boxes that only have Mic inputs, and it works fairly well.  You might have to press Play or Rec/Play, but if it has a Remote jack, you can stick a plug in there and it will stop the tape motor.

I'll probably give this a try by temporary connecting a jack (it doesn't have any inputs) and see how it sounds!

 

 

this radio doesnt even have a phono input????

not a single input of any sort! :no:



#27 Superduper

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Posted 03 March 2015 - 12:58 PM

I don't like to discourage anyone to work on their box, but this task simply isn't a diy project for a beginner with no electronic skills to attempt unless someone already did it and documented the exact steps.  The challenge of identifying the exact audio signal path locations alone require some understanding of electronics and test instruments that not everyone will have in their tool chest.



#28 Superduper

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Posted 03 March 2015 - 12:59 PM

Plus I don't have that box, nor is it even that common here in the USA.  And honestly, I doubt I would deliberately buy one either unless it was cheap at goodwill.



#29 Smeats

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Posted 04 March 2015 - 12:29 PM

I don't like to discourage anyone to work on their box, but this task simply isn't a diy project for a beginner with no electronic skills to attempt unless someone already did it and documented the exact steps.  The challenge of identifying the exact audio signal path locations alone require some understanding of electronics and test instruments that not everyone will have in their tool chest.

It's cool Superduper, I don't have much experience of electronics or the right tools for the job.

It's a good thing I asked here first and you were good enought to give some sound advice to stop me doing any damage here!  like I said before I was hoping it was going to be an easy job I could do at leisure on a Sunday afternoon!  I can't even find a schematic diagram, service manual or a data sheet for this model or any of its AKA's  helix-hx4636:
academy-pc1090
esc-unkn7
helix-hx4636
helix-hx4637
hortex-pc9090
international-unkn14
tec880
trident-unkn9
watson-rr5600

 

If I did I may have a (small) fighting chance :bang:



#30 trippy1313

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Posted 04 March 2015 - 07:07 PM

If you have, or can get maybe another boombox worth practicing on, that wouldn't hurt your feelings if you screwed up. I'd suggest building your skills on that. A more readily available and cheaper (price) box.

Like Superduper said, no box is going to be the same, but you may be able to harness some skills to be able to figure it out on this one later.

You'll never learn unless you do the research and try. But you'll feel terrible if you ruin a box you care about.