Spectra Guru Needed

fire-medic8104 · Post by **fire-medic8104** » Tue Nov 28, 2006 5:55 am

Ok, I recently bought a number of radios from a government auction. They programmed fine, disabled the securenet and got rid of the box, and recieve great.

Now here's the problem. When I key up the radio, it is transmitting but with no audio. I can see it on my wattmeter and I can hear it on another radio, but I can't hear any voice. I was using a DTMF mic that I thought was good, so I ordered another one from Ebay and it is doing the same exact thing.

Anyone ever run into this problem?

These are dashmount Vhf Units. Can post any info needed.

kcbooboo · Post by **kcbooboo** » Tue Nov 28, 2006 7:49 am

The first thing I'd suspect is "...removed securenet..." Since this has to intercept the TX and RX audio, I bet you need a jumper changed/added to restore regular MIC audio into the radio.

Try some of the built-in test features via the control head. These can generate PL, MDC, and DTMF frequencies internal to the radio. At least you'll know if the problem is before or after the audio chip.

When all else fails, time to trace the MIC audio from the control head into the command board and then to the RF board to see how it does. Service manual time.

Bob M.

fire-medic8104 · Post by **fire-medic8104** » Tue Nov 28, 2006 8:03 am

I have done alot of these and never had a problem in the past. Though these are the first dash mounts I have done most of the other ones have been trunk mounts.

On a side note, there is a cut out in the bottom of the radio that has a plug sticking in a board that is where the securenet box plugged in. I wonder if that plug being in there crosses the audio somehow.

I have the service manuals what would I need to trace the audio? Is this something I could see voltage on or does it require a special piece of equipment?

kcbooboo · Post by **kcbooboo** » Tue Nov 28, 2006 8:31 am

The best piece of equipment is an oscilloscope as it will show you the audio signal as well as DC voltages. You could make do with an AC voltmeter but the signal levels will be in the millivolt range and not many meters are good down that low.

I also have a dash-mount Spectra with the cutout underneath. I never knew what it was for, but I suspect it does intercept the TX and RX audio paths. Whether simple jumpers could be added to it is unknown. If you can remove that board entirely and put in a regular interface board, that might just get it working.

You could also try to trace the MIC audio line from the control head, through the interface board, and into the command board. An ohm-meter would be the best tool for this, but do it with the interface board sitting alone, not plugged into anything. You may have to work it back from both ends and find out which pins on the securenet connector pass the audio. Then either add a jumper or solder a wire as needed to get the audio signal flowing again.

Some of the info is in the basic service manual and some is in the detailed service manual (which is No Longer Available - I just found out today).

Bob M.

motorola_otaku · Post by **motorola_otaku** » Tue Nov 28, 2006 9:06 am

fire-medic8104 wrote: On a side note, there is a cut out in the bottom of the radio that has a plug sticking in a board that is where the securenet box plugged in. I wonder if that plug being in there crosses the audio somehow.

DING DING DING

I had one of those once. If you pull the control head, there is a weird interconnect board in there that routes mic audio through the external securenet box. Replace it with a HLN6285 and you'll be good.

edit: You can also add some jumpers to the existing board and make it workable, but I didn't save my work. I do remember that it wasn't hard to figure out, though.

fire-medic8104 · Post by **fire-medic8104** » Tue Nov 28, 2006 9:28 am

Are the HLN6285's hard to come by or very expensive? Or anyone know how to jumper it possibly? I appreciate all the help.

motorola_otaku · Post by **motorola_otaku** » Tue Nov 28, 2006 9:35 am

fire-medic8104 wrote:Are the HLN6285's hard to come by or very expensive?

$50.75 list in MOL, but that's Motorola. Market value is around $5 - $10.

I just threw that number out because that's the current part. Any normal Spectra control head interconnect board will work, unless your control head shows as an advanced type in the RSS or the MLM firmware is 6.xx or greater in which case you'll want to do this mod (quoted from batlabs.com)

Take your your 6058's and 6066's and isolate pins 4,5,22,and 29. To find these pins, look at your interconnect board while it is still in the radio after taking off the control head. They will be the pins at the top of the board, not to be confused with the lower black plug which the control head mates with.

Starting from the top row of pins at the very left which will be pin 1. As you get to pin 6 you will see that pin 7 is missing and then continues to pin 8 all the way to the far right which will be pin 19. Pin 20 starts at the bottom left bellow pin 1 and proceeds to the far right which will be pin 38.

You can cut the traces to each pin or just unsolder it and remove it like a bad tooth.

You now have an HLN6285.

Will · Post by **Will** » Tue Nov 28, 2006 11:46 am

That is correct, you need a jumper on the plug for the external Securenet box.

I will look up the pins that need to be jumpered for 'normal' operation. No need to waste the interconnect boards and try to find the non Securenet ones.

fire-medic8104 · Post by **fire-medic8104** » Tue Nov 28, 2006 2:46 pm

Thanks Will. These pins we are talking about jumpering are the ones coming from the securenet board to where the securenet cord plugged in or the interconnect board that goes to the control head? I kinda got lost (which happens often).

kcbooboo · Post by **kcbooboo** » Tue Nov 28, 2006 2:56 pm

These would be the pins you can see when looking up into the bottom of the radio where the securenet cable plugged in. These are on the inter-connect board between the control head and command board.

A regular radio doesn't have the cutout or the pins, just straight wiring on a circuit board.

Bob M.

fire-medic8104 · Post by **fire-medic8104** » Wed Nov 29, 2006 8:01 am

Ok, that makes sense. Once Will lets me know which one to jumper, I should be able to just solder a jumper on the plug, right? Or is there a better way to do it?

kcbooboo · Post by **kcbooboo** » Wed Nov 29, 2006 8:13 am

If the pins are adjacent, you could use a two-pin jumper, like the kind you find in PCs or on their hard drives. Also, wire-wrap technology can be used if you have it. I would surmise you'll never use securenet so soldering a wire will work fine but it's just a little bit messy.

By the time you hear from Will, you could trace the wires yourself, if you have all the required manuals.

Bob M.

fire-medic8104 · Post by **fire-medic8104** » Wed Nov 29, 2006 9:52 am

The spectra manual I have came from a government auction and doesn't show it. So I can't find any reference to it. It appears that several pages are missing. I have had a need for the manual since I bought it a year ago, now find out pages are missing, go figure.

motorola_otaku · Post by **motorola_otaku** » Wed Nov 29, 2006 11:10 am

kcbooboo wrote:If the pins are adjacent, you could use a two-pin jumper, like the kind you find in PCs or on their hard drives.

They're not. I had to cut a trace and solder a jumper across another on the board itself.

edit: 8104, as you know, I live on the southeast side of H-town. I have a couple of 6285s and some modded 6058s and 6066s. I'll happily trade you one of either for the your government board, then I'll mod it, take pictures, and then we'll all know.

kcbooboo · Post by **kcbooboo** » Thu Nov 30, 2006 7:32 am

I looked at my board - HLN6258A (the radio does not currently work). Starting at the MIC jack on the front of the control head, pin 8 is MIC HI. This is the bottom row, 2nd pin from the right, next to the raised pin.

This comes out the back of the control head on pin 27, bottom row, 2nd from right when looking at the back of the head.

On the interconnect board, control head pin 27 goes to the 24-pin securenet connector. If it's numbered the same as the control head connector, this comes out to be pin 19.

My board has a blue jumper going from pin 19 to pin 6 (bottom row to top row). As I suspected, this carries mike audio through to the command board.

Pin 6 makes its way, on the front of the board, to the command board connector pin 6, which is MIC HI into the command board. I actually ohmed the full circuit; MIC HI on the mike jack does make it to the command board connector pin 6.

Hope this helps. Of course, your mileage may vary.

Bob M.

motorola_otaku · Post by **motorola_otaku** » Thu Nov 30, 2006 8:18 am

Holy crow.. yeah, that's it.

I'm hooking up with 8104 this weekend to pick up his board, and we'll see if that's all there is to it.

Will · Post by **Will** » Thu Nov 30, 2006 11:58 pm

I just checked a HLN6282A interface board used with an external Securenet housing today.

Pin 6 and 18 do need to be jumpered. Bob's photo shows a Berg jumper on the two pins. The board I have has a soldered in jumper which is the same circuit.

fire-medic8104 · Post by **fire-medic8104** » Fri Dec 01, 2006 5:36 am

So basically I need the blue jumper or make one. As usual you guys come through. Thanks for all the info.

kcbooboo · Post by **kcbooboo** » Fri Dec 01, 2006 7:14 am

Connect those two pins any way you can:

- use a push-on jumper like the one in the photo.
- use a piece of wire and solder it across the two pins.
- solder a piece of wire across the pins on the back of the connector.

Bob M.

fire-medic8104 · Post by **fire-medic8104** » Sat Dec 02, 2006 12:12 pm

Well, went to radioshack today and picked up some shorting jumpers and plugged it in. Instantly went to working. Thanks to everyone for all the help. It's alive