How to connect ext audio to GL1200 radio


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SlowTyper
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How to connect ext audio to GL1200 radio

Postby SlowTyper » Sat Mar 09, 2013 5:29 pm



Here is how I connected external audio (my GPS, w/ MP3 player) to my GL1200 factory radio. Hopefully, this will help anyone else attempting to do the same.

First, thank-you, to whomever posted schematics for the RM-1100 radio on the Internet.

The approach I took was to find the ‘summing junctions’ in the radio, where the Cassette and FM Radio signal paths join to go to the audio amplifier [and intercom] sections. First, I soldered 27K resistors to these junction points, so the my external audio source would not short out the Radio or Cassette signals. I then attached a short shielded cable to these resistors, which I ran out the back of the radio chassis through a small hole. I then added an audio connector (earphone jack) to this cable pigtail, so that it was possible to get the radio in and out of the fairing.

I found I could run my added pigtail external audio wire below the factory radio connector, and into the steering head area. From there, I ran it along the left edge of the opening and tied it to the existing wiring panels so it would remain clear of the front forks and steering head. I then ran a cable to from my external audio source (GPS), and plugged it into my new added connector.

This approach has worked well. If the radio is OFF, and no cassette is inserted, I hear only my external audio thru the radio speakers and/or intercom. If the radio or cassette is playing, I hear both. In the case on my GPS, I can hear audio turn prompts over the radio station audio I am listening to.

The picture shows the L/R audio junction points I connected to, marked with red dots. This circuitry is near the back of the radio on the bottom side of the circuit board. Thus, you must temporarily remove the circuit board (the one with the audio volume controls) in order to solder these connections. It is a bit tedious, but for me, it was well worth it.
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BOSNBOB
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Re: How to connect ext audio to GL1200 radio

Postby BOSNBOB » Sun May 05, 2013 5:03 pm

Hello I have a 1986 1200 SEI and the radio in mine is RM-1400A is it the same wiring hook up as the RM1100 and if not do you have the diagram.
BMC SW/USN RETIRED
1993 Aspencade

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SlowTyper
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Re: How to connect ext audio to GL1200 radio

Postby SlowTyper » Mon May 06, 2013 9:43 am

Sorry, but I do not have a service manual / schematic for the RM-1400A, nor do I know if the applicable portion of the circuitry is the same. A Google search implied the service manual is available (for a price), but since I have not seen its contents I of course do not know how helpful it would be -- it may or may not be useful to you...

You could take your radio out and have a look. If your circuit board looks identical to that pictured above, the circuitry is similar enough that the scheme should work. If not, then you will no doubt need a schematic to figure out how to accomplish the same thing with different circuitry.

w4r
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Re: How to connect ext audio to GL1200 radio

Postby w4r » Mon Nov 18, 2013 5:52 pm

1. You indicate to install 27K resistors at the two red dots (junction points). Could you clairify. Do you connect a 27K resistor at each location? Or, do you connect one 27K resistor between the two points?

2. Does it matter in which dirction the resistors are connected - Positive to negative direction; or are the terminals connected to one red dot and the other red dot?

3. As my FM has no output and the cassette has little or no volume does this make any difference?

w4r

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SlowTyper
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Re: How to connect ext audio to GL1200 radio

Postby SlowTyper » Mon Nov 18, 2013 8:24 pm

1. I used two resistors - one for each channel (L/R). If you connect each audio input channel wire directly to its corresponding red dot (one is L; the other is R), then it can potentially short out the radio audio. The 27K resistors limit how much the external audio signal can shunt the existing audio, which in turn let's me still listen to my FM/cassette even when my GPS (external audio) is making turn announcements. So, in summary, connect each channel (L/R) of your external audio to its respective resistor, and then connect the other end of each resistor each to its respective red dot. Which red dot you use for which channel (L/R), will determine whether the external audio has L and R switched around or if the channel play on the correct side.

2. Resistors are not polarity sensitive. You can swap them end for end. You may notice +/- notations on the circuit board. That is because capacitors (on the other side of the board) are connected to the red dots - and many capacitors are polarity sensitive. The factory notations on the circuit board simply help a repairman install replacement capacitors the correct way.

3. Whether your current problems with your FM & cassette will make a difference or not depends on what has failed. If the problem(s) is prior to the point of the 'red dot' in the circuitry, then you should be OK. However, the red dot just happens to be the point where the FM & cassette audio signals are joined (my circuit simply joins a third signal). So, there is a good chance you have an issue with the audio circuitry that will affect all audio, including the external audio you wish to add. If your intercom works and if the FM & cassette can play through the headset, then there is a good chance your external audio will play through the headset also. This scenario would imply there is a high likelihood that your power amplifier (or even more likely the auto volume unit) has failed, in which case nothing will play through your speakers.

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Re: How to connect ext audio to GL1200 radio

Postby w4r » Mon Nov 18, 2013 11:13 pm

Thank you very much. I guess l will give it a try - if I can get my nerve up. I know zip about electronics.

W4r

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goldper
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Re: How to connect ext audio to GL1200 radio

Postby goldper » Sun Feb 02, 2014 2:03 pm

Hi.

Where did you connect the shield ?


Regards

Per

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SlowTyper
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Re: How to connect ext audio to GL1200 radio

Postby SlowTyper » Sun Feb 02, 2014 2:27 pm

I connected the shield to a ground trace on the circuit board - I don't recall the precise location, but was probably near or at the volume control.

SidAbma
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Re: How to connect ext audio to GL1200 radio

Postby SidAbma » Mon Feb 03, 2014 11:13 pm

My radio on my 85 LE can totally lose reception at a traffic light, and when rolling forward or back 10" get clear reception back. Are all these stereo's that way, or just mine? Would an extra external amp help to receive FM signals better?

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SlowTyper
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Re: How to connect ext audio to GL1200 radio

Postby SlowTyper » Tue Feb 04, 2014 2:09 am

Concerning spot reception loss, the simplest solution is to stop a foot back, and then roll forward if needed.

A booster will not help. You need a "true diversity" receiver to address the problem, which is a radio that has two antennas and automatically and inaudibly switches between the two for the best signal.

The problem is called 'multi-path' reception. Specifically, two or more signals arrive at your antenna, but take different paths to get there. Since it takes longer for the signal traveling the longer path to arrive, the various signals are not in sync. When the distance difference is a half wavelength of the signal, the signals will cancel each other out! (Consider a wave that starts with a positive voltage, goes negative, and then back to positive again, repeating the cycle over & over. At the half-way point, the positive and negative exactly balance out to zero.) When you move, it changes the distance of one signal path more than the other, such that you are no longer at the half-wave point that results in full signal cancellation.

Another impractical solution (beside trying to find a true diversity FM radio) is rather than using a vertical antenna, use a circularly polarized receiving antenna (assuming the FM station is using a circularly polarized signal -- most do). When a circularly polarized signal bounces off a reflective surface (the way/reason multi-path occurs; your problem doesn't occur in open areas) the circular rotation reverses, eliminating the opportunity for cancellation. Thus the only way multi-path can become an issue with a circularly polarized receiving antenna is when an even number of reflections occur (two wrongs make a right!). However, after two (or four) reflections, that signal is typically too weak to cause complete cancellation. (This is mostly theoretical, since I know of no FM vehicle antennas that are circularly polarized. However, I have seen this solution employed in other situations. FYI, my Cadillac actually has a true diversity radio, with antennas in both the front and rear windows specifically to address this issue.)

Ok, ok. I know. TOO MUCH INFO!. Which is why I said to just stop early and nudge forward if needed. OR get out of town, and ride in the open spaces!!

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Re: How to connect ext audio to GL1200 radio

Postby SidAbma » Tue Feb 04, 2014 9:44 am

Hi Slow Typer
Gold Wings have their 2 antenna that makes them so recognizable going down the road.
If the whips were to be changed to an antenna like I had way back when on the windshield for the first cell phones, or if there could be a way to coil the last 6" of these antennas, it might make the difference?

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Re: How to connect ext audio to GL1200 radio

Postby SlowTyper » Tue Feb 04, 2014 12:07 pm

SidAbma,

Your idea of 2 antennas is on the right track, but dual antennas alone will not resolve the problem of multi-path reception.

Dual antennas will be directional, since signals arriving from one direction will be in sync and add together while signals arriving from a substantially different direction will be out of sync and subtract from each other.

So, while it would be helpful if multi-path signals would arrive at sufficiently different angles that one would be boosted and the other suppressed by a directional antenna system, after going around a bend in the road your directional array my do more harm than good since it would no longer favor the desired signal path.

The thing that makes diversity receivers work is the fact that in addition to two antennas, they consist of two separate radios/tuners. And furthermore, rather than the two signals being joined (a scenario that will always be susceptible to multi-path), only one signal or the other is used. That is, a diversity receiver transparently selects the best signal and mutes the poor signal.

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Re: How to connect ext audio to GL1200 radio

Postby SidAbma » Tue Feb 04, 2014 5:21 pm

So all Goldwings have this problem? Why has Honda not found a better way, or are we all supposed to play cassettes?

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SlowTyper
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Re: How to connect ext audio to GL1200 radio

Postby SlowTyper » Tue Feb 04, 2014 6:16 pm

All vehicles have this problem in the city, where buildings reflect FM signals. And AM signals get weak under bridges. That's the way radio propagation works.

Well, not all vehicles... A few expensive cars have expensive radios that employ diversity receivers.

Wouldn't you rather just roll forward a foot or so to fix the reception, than pay a lot more for your radio? And not have to deal with two antennas located more than several feet apart?

An no, you're not supposed to play cassettes these days. You're not even supposed to play CDs... You are supposed to listen to your MP3 player, which is what my post explained one way of connecting up (as an alternative to using a FM modulator). Or listen to AM radio!! :lol: :lol:

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Re: How to connect ext audio to GL1200 radio

Postby SidAbma » Tue Feb 04, 2014 7:47 pm

I'm Old School. I don't have an MP3 player. Where we live there are no tall buildings, unless 2 story is considered tall. No my bike just has poor reception. Riding along the side of the lake at 15 mph it will fade in and out.

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lopet
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Re: How to connect ext audio to GL1200 radio

Postby lopet » Wed Mar 12, 2014 8:08 am

Hi SlowerTyper
I have two questions. Are the resistors necessary if you only want to listen to your external audio i.e. iPhone (including MP3 and GPS) and never the radio?
Wouldn’t it have been easier just to connect the external audio to the Auto Volume Connector? It was my plan to do that, but then i saw your post.

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SlowTyper
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Re: How to connect ext audio to GL1200 radio

Postby SlowTyper » Wed Mar 12, 2014 8:43 am

Lopet,

Yes, you could eliminate the resistors, and it would play at a slightly higher volume due to the slightly lower input impedance. However, you would also end up with a direct connection from the radio circuitry to the 'outside' world, which would make it more susceptible to transients and any voltage spikes (imagine if your ground wire became loose).

You could optionally connect to the auto volume control, but that would eliminate the possibility of playing the audio through the helmet earpieces, since the auto volume control provides an audio signal only to the power amp & speakers.

A radar detector is a good candidate to connect to the auto volume control, since it is unaffected by the volume control on the radio (you still here the audio even with the radio volume turned way down), and the warning gets louder the faster you are going!

And while I am on the subject of the auto volume control, I will mention that if you wish to add a subwoofer to your system (I have), you need to connect its amplifier to the output of the auto volume control, so that the subwoofer also increases in volume with speed.

Tim (the Slow Typer)

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goldper
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Re: How to connect ext audio to GL1200 radio

Postby goldper » Sat Mar 22, 2014 3:19 pm

Hi.

Well, thank you Mr. SlowTyper.

You have just saved me a lot of work.

I have now connected my Cell Phone, a new CB radio and a PMR radio to the audio system on my GL1200 SEI 1986.
If you ever find yourself in my area, be sure to collect a cold Beer.


Regards

Per
Herlev
Denmark

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Re: How to connect ext audio to GL1200 radio

Postby Rapter » Tue Mar 29, 2016 8:09 pm

Hi comunity
I don't know if being in UK gives me more freedom, what with the FCC in USA but I recently purchased a 12v fm transmitter which allows me to connect either MP3 player (using earphone output), SD card (the old 1" sized ones) or USB stick (pen drive).
This then is transmitted on normal 88-108fm (finding a place without a local station). The radio on my GL1200 is then tuned to this frequency. I use 90mhz but any 0.1 step between 88 and 108 is possible.

I am unsure of the range of the transmitter, but I figure it is only a few yards (maybe 50, maybe 10) but it's not much.
The device is plugged into a handy 12v outlet (cigar lighter type) I have in cockpit. Stored in top box when I am off the bike.
I load my playlists onto SD memory cards (even 1 gig gives hours of music) and can choose the mood as suits me.

This seems a more practical solution than fitting new kit and I paid around $8 yes eight for a really cheep one from China (love ebay) as I wasn't going to pay $30+ if it did't work. Works well enough to keep till it brakes (which it will, it's from China and was £5.25 for God's sake hahaha).

So I have no clue if it's legal .. I certainly aint worried about it ..
and have all the tunes I can cruse to played as Soichiro Honda intended (more or less).

No ear buds, extra wires (like we need more), not Bluetooth (so doesn't interfere with my comms), simply plug, set and play.




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