BCD536HP Discriminator and inside look

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N9JIG

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OK, I did this so you won't have to. Don't do it if you don't want to void your warranty. I am not responsible for any errors or if you toast your scanner.


I took my 2-day old BCD536HP apart and found the discriminator jack. While I was there I took some photos to satisfy the curiosity of those less inclined to incur the wrath of the warranty gods.

First, how to safely disassemble the radio:



The BCD536HP is mechanically similar to the prior BCD996XT and related radios. It is a DIN case surrounded by a second case for non-DIN mounting.

Remove the outer case (the black one) by pulling the 4 screws on the back of the radio case's tabs. Then remove the 4 screws on both the right and left sides of the interior clam-shell case. The top peice comes off easily but be very careful removing the lower case, this has the speaker mounted on the case and the wire for the speaker is connected to the board. CAREFULLY remove the speaker wire from the main board!

With the radio right side up look almost dead center at the main board and see the conveniently labeled "DISC OUT" solder pad. Could we be so lucky? We could!



Tack solder a small insulated wore to this pad using just enough heat to melt the solder and provide a good electrical connection. Place a bit of electrical tape over this after running the wire to your jack point. Run the wire to the side of the board where there is plenty of room between the board and case edge to where you decide to mount your jack.

Placing a jack of your choice someplace on the rear panel is the best bet. On other scanners of this series I drilled a 1/4 inch hole thru the threaded rear brace hole. Since I don't use that and it is clear behind it it does the trick. I use an RCA jack, some people prefer other solutions. You could run a pigtail thru the hole or modify an existing jack. Since the 536HP does not have the rear panel Record Jack of it's predecessors that isn't an option.

If the jack you chose grounds to the case then you are done. Some people prefer to put in a tantalum capacitor or a small resistor in their discriminator jacks, go for it if you want. I usually don't and have never had an issue. If you use a pigtail the be sure to ground the shield.

When reassembling the radio remember to plug in the speaker! I have forgotten this many times and had to go back and tear it all apart to reconnect it.

Now more pics!

First is the overview of the main board:




Next here are some protected areas. The epoxy is usually used to protect the region switches and other parts of the CPU to satisfy regulations and prevent tampering with frequency ranges etc.




One of the issues Uniden had with prior scanners is that the ribbon cable from the display/control daughter board would loosen up and need to be reseated. I had this happen on a couple BCT15's and a 996. Now they put a dab of glop to help keep this from shaking out.







The photos should be decent enough quality to view most of the goodies inside it. While most people do not need to tap the discriminator a lot of people are curious about the inside of their radios. The 536's guts look remarkedly similar to those of the earlier BCD996XT, BCD996X, BCT15X and BCT15 that it evolved from.

Right off I noticed that there is no record jack, the rear USB port (Used for the WiFi dongle) is there now. I haven't read up enough to see if there is a setting or selection to allow the rear speaker jack to be set up as a Record jack for constant level output regardless of the volume setting.

The board appears to be typical surface mount tech with multi-layer pathways. It appears uncrowded and perhaps could have been made much smaller if they wished. It appears well labeled thru out.
 

mikewazowski

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If I could +1 this I would! Thanks, it's greatly appreciated. This scanner will be replacing a tapped scanner in my vehicle so tapping it is a must.
 

RadioDaze

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Thanks for taking one for the team!
This unit really is crying out for a line-level audio output. I wish that was done during the manufacturing. I don't even stream a feed, but I like to send audio to a mixer with other radios.
 
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awattam

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When soldering to the motherboard of a scanner...

I prefer to `tin' the exposed end of the tap wire with a little solder. This served two purposes. IF you are using multi strand wire for your tap then it solders these into one item. Secondlywhen you come to solder this wire to the motherboard, you only need to melt the two soldered elements (the end of the tap wire and the solder on the motherboard) together and therefore you are only applying heat to the scanner for a brief second.

Just a little tip I learned at college.
 

Markb

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It's a shame that discriminator taps don't come standard on scanners in this day and age. I am inclined to wait for 6 months to a year until the headphone jack issue and any other potential hardware bugs are ironed out. Thanks for cracking the shell!!!

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N9JIG

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It's a shame that discriminator taps don't come standard on scanners in this day and age. I am inclined to wait for 6 months to a year until the headphone jack issue and any other potential hardware bugs are ironed out. Thanks for cracking the shell!!!
The overwhelmingly vast majority of scanner users would never need a discriminator tap, especially now that there are built-in features like PL/DPL decode and CC-Dump in high end scanners.

The "One Percenters" like us can add taps as needed.

TTTT, I actually won't be adding a tap to this scanner for now, I don't really need it. I have a batch at home if I need one. I might try my hand at some DSD decoding eventually so that might change things but outside my R8500 and a BCT15 connected to a couple external decoders I am pretty much not in need of tapped radios these days.
 

Markb

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I agree that many users don't need a tap and probably wouldn't know what to do with it if it did have one. The thing to me is that it would probably cost Uniden mere pennies to add it and then we wouldn't have to worry about voiding our warranties. i do think there is sufficient demand, but I think that one big roadblock to people using applications like Unitrunker or DSD+ is that they are afraid/unable to open up their radio and start soldering.

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ffexpCP

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Can you get a close up of the on/off knob solder connections? I'm thinking I may be able to modify for ignition sense with a relay.
 

ffexpCP

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Have you checked to see what you get with the AUD_OUT? Maybe this could be tapped for line out / recording.
 

SCPD

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car

Can you get a close up of the on/off knob solder connections? I'm thinking I may be able to modify for ignition sense with a relay.
Why would you wanna do that theres 3 wires on the DC cable one ground (black),one orange (ACC or Switched) and one is Red for (constant 12volts),if you connect the third it should turn on off with the car key.
If thats not the case hook the red to the ACC 12 volts in the car for on off with the car,I would leave it constant so you can play parked.
 

N9JIG

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Why would you wanna do that theres 3 wires on the DC cable one ground (black),one orange (ACC or Switched) and one is Red for (constant 12volts),if you connect the third it should turn on off with the car key.
If thats not the case hook the red to the ACC 12 volts in the car for on off with the car,I would leave it constant so you can play parked.
The orange wire is for lighting control only, it allows one to vary the brightness of the scanner's lighting with the dashboard lights.
 

N9JIG

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Can you get a close up of the on/off knob solder connections? I'm thinking I may be able to modify for ignition sense with a relay.
Here is a cropping of the daughter board if it helps. I already reassembled the radio but hopefully this will help.

 

ffexpCP

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Why would you wanna do that theres 3 wires on the DC cable one ground (black),one orange (ACC or Switched) and one is Red for (constant 12volts),if you connect the third it should turn on off with the car key.
If thats not the case hook the red to the ACC 12 volts in the car for on off with the car,I would leave it constant so you can play parked.
As was already mentioned the orange is only for backlight.

I'm interested in simulating turning it off with by knob by using a relay. I'd have the power wire go to battery (always hot) , and the new ignition sense to accessory power (switched).

This would allow the radio to write settings to the memory, and power down.
 

W2GLD

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Unlike the BCD996XT series, it appears Uniden has moved over the speaker jack into the place holder where the original REC jack was in order to make room for the USB port for the WiFi adapter.

With that said, you can also add a wire to the AUD OUT port on the board when you add the one for DISC' the oscilloscope shows a leveled audio at that port, which is unaffected by the volume control. This is the exact same setup as the BCD996XT units. The level is just a hair lower than the REC port provided; however, with a decent sound card and feed computer setup, this is easily overcome.

So to summarize, yes, there is low level line out audio available at the AUD OUT port on the board, one wire this port and another to ground and you're in business for a feed receiver.

I will also add, for those with the external speaker jack issues, that the wave form on the speaker jack is MUCH different from the AUD OUT port; it appears that some additional audio processing is being done there now that is not the same on the BCD996XT's.
 
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y84media

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So what parts were drown in the BLACK resin? That screams "don't touch"....as if modifying anything under the resin could result in undocumented features. Not trying to start rumors or trouble, just letting my imagination run wild with the possibilities. :D



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Markb

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So what parts were drown in the BLACK resin? That screams "don't touch"....as if modifying anything under the resin could result in undocumented features. Not trying to start rumors or trouble, just letting my imagination run wild with the possibilities. :D



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You might want to reign in the ol' imagination a bit. It's probably the circuitry that, if modified, would enable you to receive analog cellphone traffic which is all but history anymore. Likely not anywhere near worth the trouble.
No easter eggs there........

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sixtytwo

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Interesting - discriminator tap, but not seeing any I and Q branches so labelled, nor an IF tap.

Not saying they aren't there - but if they are, they're not labeled as nicely.
 
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