RH-96 rewiring

[N9JIG]

I have 2 each 996XT and BCT15X in my van, all with RH-96 remote heads. I have on 2 occasions now damaged the fragile front serial port on the scanner to the point where it will no longer remain connected.

I did a little poking around in a BCT15 and found the points in the radio where the cable connects and have been thinking of installing a 1/8 stereo jack on the rear of the radio to allow a more secure connection. This would also allow the use of a regular male-male audio cable to connect the radio to the remote head.

These connections are marked as "RXD2" (ring), "TXD2" (tip) and "GND" (sleeve). They correspond to those points on the male audio plug on the remote head end of the cable.

My issue is that these solder pads are obstructed by the front panel of the radio and are difficult to access for this fumble-fingers dude. I did try to find an alternate location to tap into these points to no avail.

Below is a photo of the daughterboard directly behind the front serial port/earphone jacks on the radio. (It is identical on the BCT15, BCT15X, 996T and 996XT.)

There are small holes alongside each pad but I can't verify that they connect to the solder pads.

My question is this:
Has anyone successfully remoted the front serial port for this purpose? Also has anyone found an alternate and easier to access connection point?

(I did try the rear serial port, there seems to be no continuity between the front and rear ports.)

 

[mancow]

Why don't you use your continuity meter to check if the plated through holes go to the pads. They appear they do.

 

[N9JIG]

I just did, and there is continuity, but they are still difficult to access due to the lip of the front plastic panel.

I tried to disassemble and remove the daughter board to allow a wire to be pushed up from the other side but I can't get the board out.

I then took out the 5 screws holding the entire front assembly on and rotated it out of the way of the main board but the daughter board still won't budge and the holes are obstructed by the plastic framework of the jack assemblies.

 

[scanbc780]

Do you use the rear serial port for GPS? If not, why not just make a cable for the RH-96 and come of the back that way.

If you need really small wires to go from the front header board to a 1/8" jack in the rear, you can take an old parallel printer cable apart and use the wires in there. They are very thin and would work perfectly for your application with many colors to chose from.

 

[N9JIG]

I do need the GPS connection on the rear so that's out for that.

I have not seen anything where anyone successfully used the rear serial for a RH-96 anyway.

 

[scanbc780]

Ah, it looks like extending the front jack to the rear would solve it. The fragility of the front jack is the reason I don't use it. I have successfully used the rear serial for the RH-96 on a BCD996T and an XT.

In this post I was testing the distance one could go. http://forums.radioreference.com/907924-post16.html

DB-9 Pins - 1/8" connections
PIN 2 - RING
PIN 3 - TIP
PIN 5 - SLEEVE

 

[N9JIG]

Well, the experiment seems to have worked. I had to disassemble the front panel after removing it from the radio side frames. Once I removed the screws holding the metal backing to the faceplate I was able to remove the daughter board and it's plastic base.

I then used a couple strands of magnet wire thru the aforementioned and pictured hols, soldering them to the solder pads. The other end went to a stereo 1/8 jack I mounted on the rear panel. I had to mount it in the threaded hole after drilling it out since the rear panel is made up of two pieces of metal and is too thick elsewhere for the jack to mount with it's retaining nut.

I did not need to run a separate ground wire, it is grounded to the case. The wire from the daughter board to the jack is only a couple inches and when connected to an RH-96 it worked fine.

As a proof of concept I think of this as a success. I plan on doing this to the couple radios I have already damaged the front serial port unless I find another, easier point to access the front serial port. This is unlikely I fear as there appears to be a level converter on the daughter board, so a direct wiring point is probably non-existent.

BC780: Have you tried to run GPS and an RH-96 from the rear serial port at the same time?

 

[scanbc780]

From what I gather it won't work as they use the same pins, so I've never attempted.

 

[N9JIG]

Success!

Well, I modified all 4 of my scanners in the car (2 BCT15X and 2 BCD996XT). I had used an older BCT15 as a guinea pig for the proof of concept and it works great.

Here are the steps I took. Remember that this involves disassembling of the radio and is not for the feint of heart. It will void your warranty and I take no liability for any damage etc.

It works on the BCT15, BCT15X, BCD996T and BCD996XT. I used a stereo 1/8 inch panel mount jack from RadioShack.

1) Remove the 4 screws holding the black outer case on (rear of the radio)
2) Remove the 8 screws holding the inner silver case halves.
3) When removing the bottom (speaker side) case half be careful and remove the speaker connection gently.
4 Remove the 3 knobs on the front of the radio (Volume, squelch, rotary) then remove the restraining nuts.
5) Remove the 6 small screws holding the front panel to the metal structure.
6) Remove the 5 screws holding the front panel the the main frame. 2 each are on the right and left sides and 1 screws into the main board frame.
7) Remove the screw on the small daughter board holding the front serial and earphone jacks.
8) Carefully separate the front panel from the radio and loosen the daughter board from it's plastic saddle. Don't be surprised if the clear plastic keyboard light diffuser and plastic trim pieces from the volume and squelch panel drop off.
9) Drill a hole on the rear panel to fit the jack. (I drilled out the threaded hole above the barcode label, this allowed it to be used as the drill guide.) Be careful not to drill thru the components inside the radio!
10) Solder 2 fine wires to the Tip and Ring terminals of the jack. Don't worry about the common (sleeve) as the case ground takes care of this.
11) Mount the jack on the rear panel.
12) Solder the Tip wire to the solder pad marked TXD2 and the Ring to RXD2 on the daughter board. I pushed the wires up from the underside of the daughter board visible in the picture earlier in the thread. Do not over heat the joint to prevent damage.
13) Test for proper operation.
14) Reassemble the radio in reverse order.

This provides a much more secure connection than the fragile front serial port. This also allows you to retain use of the front port for programming if needed. I don't think you can program and have the RH96 working at the same time though...

This also allows you to use a common male-male 1/8 inch stereo jumper, of the type commonly used for iPods etc.

Enjoy!

 

[K4APR]

I have not seen anything where anyone successfully used the rear serial for a RH-96 anyway.

I can attest that using the rear DB9 works fine for this. I had one built up for our demo display, back when we were selling the remote mount kits out on the road. Very simple cable. DB9 pins 2,3 and 5.

 

[N9JIG]

I can attest that using the rear DB9 works fine for this. I had one built up for our demo display, back when we were selling the remote mount kits out on the road. Very simple cable. DB9 pins 2,3 and 5.

I thought about using the rear serial port too but I didn't want to lose the GPS functionality. I use GPS extensively.

Now that I have done it I can do a mod like this all in a half hour or so.

Since in my vehicle the fronts of the radios are a little hard to access relocating the serial port to the rear panel really helped, it is almost impossible to get the front port plugged in sometimes.

 

[KX4KDH]

Thank you guys for this bit of info. I want to go from the DB9 to the remote head. Someone said pins 2,3, and 5. Just need to figure out which goes where. That little USB port is, indeed pathetic.

 

[drsl2000]

"RXD2" (ring), "TXD2" (tip) and "GND" (sleeve).

This isn't a phone connection; it's a bidirectional serial interface.
RXD2: Receive Data, port 2
TXD2: Transmit Data, port 2
RTS: Request To Send

 

[KC8ESL]

I probably would have used a more obscure connector such as a 5 pin DIN or mini-DIN as a 3.5mm jack is associated with audio more often than not. Ideally, it would be a cable interface people don't typically have easy access to.

On the flip side, if you are like me you'll probably use the radios until their unfortunate deaths so no one but yourself would ever have to deal with the connectors...

As a concept, I really like this idea and when I purchase a 996xt or 15x, it will be among the first things I do to the radio. Warranties never seem to work out in my favor anyways.

 

[UPMan]

We wanted people to be able to easily/inexpensively extend the cable.

 

[N9JIG]

Along with that I chose to use the 3.5 stereo jack on the back panel for ease of installation, both on the radio and for the cables involved.

Since it is the only jack with a retaining not on the panel it is unlikely to be confused with the record or speaker jacks. I do however get those mixed up all the time!

Another nice thing with the panel mount jack is that the common/ground takes care of itself so I only needed to use 2 wires ( send, receive).

 

[cifd64]

If i want to use the provided extension cable to a DB9, what wire goes to which port on the DB9? going to have one of my techs build it for me. (I am lawfully banned from modifying electronics )