Starcom1 CAB-36A cable for Radar Detectors

[Fred W]

This past weekend (while out on the chowder ride) I lost the audio feed from my Escort Passport 8500 to my Starcom1 Advance. I had been using a Starcom isolation / attenuation cable part number CAB-36A as recommended by Jeff of Bike Effects (the "A" is significant as this is the model that also attenuates the audio signal). That setup had always worked flawlessly up until this weekend.

Sunday, it struck me that I did not hear all the happy chirpy noises that I am used to in my helmet speakers when I start the bike and the Escort senses the voltage dip caused by the starter dragging the battery voltage down. Further investigation revealed that my suspicions were true, I was running around... unprotected.

Troubleshooting:

Unplugging the audio cable, the RD chirps through it's own speaker fine.

Substituting the MUS-04 isolation cable that I normally use between zumo and starcom audio jack, into position the same as the suspect between the RD and Aux jack makes the RD audio available. Hmmm... welp, sure seems like a cable problem.

The isolation part of the CAB-36A appears to be an audio transformer. I measured the resistance on the (mono) Radar Detector source end of the cable / transformer, between the tip and ring connection and get a respectable 90 ohms. On the stereo connector on the Starcom end I measure wide open between tip, ring and shield even on the 20M ohm range on my fluke DVM.

I'm hoping that someone with one of these cables and a VOM can just validate that my readings are FUBARed. I would expect the audio transformer to be 1:1 and so the Tip to ring and/or shield resistance should be the same 90 ohms on both ends.

I dropped an email note to Jeff A, but it may take him a while to get me the pertinent info from Starcom. So anyone to help me out would be be greatly appreciated (PS - I searched).

BTW - for anyone confused about tips and rings and shields: wiki that

 

[Beamer Reamer]

Fred,

I decided to help a brother out so I grabbed up my venerable Fluke 73 DVM and took some quick readings. I have the same attenuated cable and oh so love have the radar signals in my ear. Here is what I found:

Radar Detector end (mono): 92.4 ohms

Starcom end: Found 93.3 ohms between tip and shield.

Starcom end: Found 186.4 ohms between tip and ring.

Wasn't sure what to expect on that last one...not sure what it means other than mine still works.

David

 

[MartyA]

Frankly I don't understand any of that, but when I had some voice and two-way radio issues with my Starcom1 I went right to the Starcom people.

This is the email for Anna, aka

Admin1 [[email protected]]

well my email came from Admin1 signed by Anna...

Tony Starling is some sort of customer service engineer there

Sales [[email protected]]

I described my symptoms in very layman's terms to Tony. Admin1 would update me occasionally. End of a long story I sent mine back and they returned it with a new circuit board installed by them. Just cost shipping.

HTH

 

[Fred W]

Thank you both. The reading are what I was expecting (roughly) and my open circuit on the Starcom end says the isolation transformer is bad. I'll get another cable. The one that I have has a round transformer that (was) covered in heat shrink tubing. I peeled off the shrink tube and the transformer underneath is potted in some sort of silicone looking goop. I may open it up if they do not want it back at Starcom.

And Marty, I dealt with Tony Starling during the PPT-3 go-round. You might remember that the VOX inhibit wasn't working "as advertised" to inhibit the FRS radio being keyed all the time. WE got that figured out, it just had the wrong value of jumper resistance inside, so all the new ones should work OK.

I may hit him up and see if he'll give me a new cable. Ho2w long is a cable's warranty?

If not I'll drop the $45 with Jeff.

Thanks again guys. I knew I could count on this forum.

 

[Fred W]

Got a return e-mail from Jeff (Bike Effects) where he was passing along some info from the Starcom folks. The correct resistance readings for this cable are as follows:

Measuring at the mono plug end should read the transformer you will se

approx 90ohms.

The stereo plug end base to tip is open, and base to middle should read

around 500ohms.

So, this confirmed my cable is bad. Also he confirmed my cable is out of warranty, so that gives me the green light to do an electronic autopsy. First step is to carefully cut away the outer layer of shrink tubing / insulation. Next is an outer layer of semi rigid plastic tube which is used as a form to fill with the potting compound, which looks a lot like hot melt glue. Cut that away and this is what you see:

Now remove the remnants of the glue

and you have access to the resistor and audio transformer that make up this expensive cable. I found that the white wire between the resistor and ring terminal had an intermittent open. By flexing the wires I could see that break was very near the transformer end, so I cut the cable back about an inch and re-connected it.

edit: Note you will measure ~90 ohms across both the primary the secondary side of the audio transformer, much as I anticipated. The remainder of the ~ 500 ohms on the secondary is comprised of the attenuator (series 470 ohm resistor resistor) which is only found on the "A" suffiix cables, and is intended to keep the volume of the RD from blowing your eardrums out.

Warning, this work requires medium to poor soldering skills to accomplish.

Here's the reconnected transformer. I put a piece of blue shrink tube around the bare shield wire to be sure I didn't short it out later. Since the red (tip) wire was not originally connected to anything I wrapped it around the transformer terminal to serve as an additional strain relief.

My readings are now exactly as above. Now all I need to do is goop it back up with some fresh hot melt glue and put a nice shrink tube wrapper around it and I'm back in bidness.

Thanks to Beamer and Marty and especially to Jeff A from BikeEffects.com, who has once again gone above and beyond the call of duty to help out a fellow motorcycle rider!!

PS - Doesn't $45 seem a tad steep for what's inside this cable? I'm pretty sure I could crank these out for around $10 on a low volume.

 

[MartyA]

Doesn't $45 seem a tad steep for what's inside this cable? I'm pretty sure I could crank these out for around $10 on a low volume.

Does look simple enough, even to me. Seems like you should make 100% profit on a $10 cable, maybe? Maybe I'll send my cables to you for 'certification' and I'll pay you for testing / fixing them?

Briefly, my main problem was my GMRS radio would work in the morning, then late in the day wouldn't transmit. Next morning it worked fine, then again later in the day it wouldn't transmit. The little light would come on but nobody could hear me. I have to run with VOX off or else everyone would hear Sally telling me how to drive... My Starcom1 is in my tank bag so I can switch between my FJR and my FZ-1. I have a PTT-03 on my FJR, and a PTT-02 on my FZ-1 both work the same. After 2 years I finally sent the Starcom1 unit back and they replaced the insides. I hope to try it this weekend.

 

[road runner]

Nice find Fred.

I need to find some time and see if I can figure out what is wrong with mine. I think maybe I'll call Jeff and or starcom first.

I am thinking it maybe my Zumo base that could be messing things up. Although I'm not sure. I wish I new more about this audio stuff.

Art

 

[kleake]

Hmmm,,, I might have to hunt down a source for these little transformers.... I need to isolate a couple of leads from my blackberry and my gps. These are the mono versions correct? I would think you could do the stereo version as well by putting two of these in there, one on each channel. A little google search and I found the data sheet, but no prices yet. I've got too many projects at the moment, but I will be looking into this soon. Fred W, if you are interested and you make some of these, let me know, I may be interested in a couple...

 

[Fred W]

Kleake,

I may be interested in making a few for personal use, as I need to outfit a second bike with isolation for GPS and RD, and if I do make some up I'll be glad to share my experiences. But I won't likely be wanting to producing them for sale for a couple of reasons. One is I can make way more money doing my real job, so unless I get laid off in the near future I shouldn't need to start a cottage cable industry.

The other because cloning Starcom cables seems like it might be an infringement on their IP/patent rights. I guess one could just make some generic isolation cables and be safe. In which case, see reason 1.

As to your needs, unless you are powering a device from the bike there is no need for an isolation transformer cable. So hooking the Crackberry up you really shouldn't need one. The GPS OTOH, being bike powered, isolation will be a must.

 

[kleake]

Fred W, I can relate to the cottage cable industry as I find myself doing so many things for others I sometimes run out of time for my own.

As for my need for them, here is my issue. First off I run an "autocom", but my setup is similar. I run a GPS for turn by turn, but I also run the GPS on my crackberry for a "large" map that I can see all around where I am,,, as well as running MP3 tunes and "Trapster". With this being the case, I have custom wired in power devices for both of these to be bike powered. I also have a CB that is bike powered. Now, with all of these devices I am really doing pretty good, but,,,,,, the GPS gets a very minor static when I plug it in,,, but I can live with that and barely even notice it. The crackberry on the other hand, makes a much more noticable static when I plug in the power to it. Neither one is horrible, but if I don't get the power all the way plugged in on the crackberry it gives me a nice loud whine until I fiddle with it a second or two. So mostly, I "need" one on the crackberry, but would like to have one on the GPS as well. The CB on the otherhand has it's own issue. It's odd, but I put remote squelch and volume controls up front while the unit itself is under the rear seat. All works fine until I turn the volume all the way up,,, then all it will transmit is a buzzing sound. If I turn the volume down a little, it works fine. A couple of my riding buddys don't talk very loud and I have to have it all the way up to hear them. It does transmit a slight engine noise all of the time though, so I am looking into a filter to fix that too.

All in all,, too many other projects going on to be able to mess with those at the moment, and all of them I can deal with sufficiently for now anyway. If you do get time to tinker with them, I would be interested in hearing your experiences though.

 

[Fred W]

Ha ha ha. Aren't modern electronics wonderful?

I swear, since I re-entered motorcycling (about 10 years back) I've spent an equal amount of time dicking around with all this electronic paraphernalia as the bikes themselves. Bikes got (much) more reliable so we had to introduce something that wasn't so reliable to keep us all busy.

If all we had was an FJR with no farkles, I think this (and many like) forum(s) would implode.

 

[Fred W]

As I reported above, these fancy isolation cables from Starcom (and Autocom?) are just using cheap little audio transformers to provide ground loop isolation. I could have gone mail order, but decided to look at the local Radio Shack first. It seems that RS carries a small audio transformer that is quite suitable under part number 273-1374 for $4. It seems that most of the local stores stock this part too.

I was able to splice the appropriate cable ends onto one of these transformers, added the required 470 ohm resistor, as shown, for the attenuation required when using with a Radar Detector output (it prevents you from blowing your eardrums out)

The black and white transformer wires are the xfmr primary. They hook up to the tip and shield of the mono RD end. Red and yellow are the secondary. They hook up to the ring and shield of the stereo cable end that goes to the Starcom's Aux port. Polarity is unimportant. Resistor goes into the secondary side.

Shrink wrapped the individual wires to keep thenm from shorting to each other, and then used one big piece of shrink tube around the transformer and wiring. Then just squirted hot melt glue liberally into both ends of the big Heat Shrink tube which sealed it up as it shrunk the tubing and restrained the cables well.

This cobbed up cable works just as well as the $45 one from Starcom. The little ETAL P3188 transformers that Starcom uses are nice as they are a bit smaller, but the radio shack ones are readily available at your closest store.

 

[kleake]

hmmmm,,,, very good to know.... I might have to start hacking up some wires soon... I might even build one with a male on one end and female on the other end so I can use it on different devices that are pre-wired. Also I would guess using 3 of these on a cord that is used for two way communications would work as well. 1 for left, 1 for right, and 1 for mic. Why doesn't starcom & autocom just build these into their devices? Guess that would mean they wouldn't sell the $45 cables huh?

 

[kleake]

Woohoo, I added 4 of these little transformers tonight. One on the GPS since it had just a tad of background noise. Used this one as my test and it worked perfectly. Then I hacked into my blackberry cord. Put one transformer on the left channel, one for the right, and one for the mic. It works perfectly and has gotten rid of 100% of my ground loop noise. Now I just need a little filter on my CB to cut out the ignition static I get due to my remote squelch and volume controls. While I was installing these, I jumped the wires to see if there was any real difference in volume with or without the transformer. There is a small decrease, but not much, and likely not enough to make any real difference. Thanks Fred W for the helpful info that encouraged me to start hacking up my cords! I'm much happier now!

 

[kleake]

Found a "minor" issue with my cable and my blackberry. I could listen to music all day long, but when I got a call and tried to answer it, I couldn't here them at all. :blink: I scratched my head for a few days but figured it out tonight. Seems the blackberry uses the resistance in the mic circuit to determine what to do. Plug in a set of headphones and you create a short, plug in a headset and you have approximately 1k until you push the little button to answer or hang up which creates almost a short. Well, these little isolation transformers are 51 ohms on the primary side, so it was thinking I had a set of headphones, instead of a headset. Basically, I could listen to the music, but when I would answer a call it switches to the handset. Solution=I answer, then tell it to go to the headset and it works perfectly after that. :yahoo: I could add some resistance into the isolation transformer, but that would likely reduce my volume too much, so since it is a simple solution, I'll leave it as is until I am bored enough to change it.