Pro-2004 & DC Power Supply

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af0h

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Hello all. New to the forum but long time Scanner user.

Anyway, I recently picked up a good Pro-2004 with all common mods (Backlight, Speed, Channels, Thru-hole solder joints, etc.) mods already done. Works great and couldn't be happier.

Some of you with more experience than me with this model = any advantage to running this model off a good DC Supply (not a wall-wart) over the internal PS? I've let it run for several days straight (through a good filtered/protected power strip) and the case never really gets warm. I have onhand a great adjustable and regulated PS more than capable of running this and puts out a better filtered DC with lower ripple than the internal.

Any advantage of doing this, or better off using the internal 110 supply?

Also, what is the low voltage cut-off point on these models? 11v? 11.5v 12v? 12.6v? I have no problem running the recommended 13.8v, but just curious for running off of backup battery when the need arises.

Sorry for all the questions, and great to be a member here!
 

w2xq

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Frankly I'm surprised that you have a PRO-2004 with a good display panel. My -2004 faded out years ago. To your question. No problem running it on a 12vdc supply so long as the supply has the required current output. I don't remember the amps required but it can't be all that much. Actually I run a bunch of receivers and accessories on a 20a Astron supply; the radios remain cold to the touch. The supply just loafs along, and there is better voltage regulation than within the radios' supplies. Also less wallwarts and only one outet is required.
 

KC5EIB

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From the manual

Power Requirements AC 120 Volts 60 Hz 20 watts. DC 13.8 Volts 12 watts
Memory Back-Up Battery 9 Volts
 

ak4fn

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If you have a good power supply by all means use it. Bill Cheek always recommend doing this. Just one less thing not to go wrong, and it would help keep it cooler. That was/is a great scanner!
 

af0h

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Thanks all for the replies.

Tsundstrom - the display is too bright for it to be the original. Although I didn't inspect the panel too closely when I peeked inside, it almost has to be a replacement. It sure is a bright blue - even on Dim mode. Bright is almost too bright. Whoever had it also replaced the 10-ohm resistor - which is inline with the display when it's set to Bright. It's been replaced with a 22-ohm resistor. I can only guess that the larger resistor is used to limit some of the current going to the display - hopefully preventing another fade-out in the future.

Doug - thank you for the manual quote. I do have copies of the OM and SM though...

AK4FN - thanks for the tip. I wasn't aware that Bill always recommended using an external PS. My PS is based on the LM338 ( a 5-amp version of the LM317 adjustable voltage regulator). All caps shown in the spec sheet diagrams were used, some of larger values as well. I also have over-voltage protection (crowbar circuit) in the form of a Zener which activates an SCR to short the supply to ground and blow both the main and output fuses before any damage can be done externally. Yes, I tested this function to make sure it works.

Guys, thanks again. Obviously i'm not a newbie when it comes to electronics, I just want to help make sure that this baby keeps on ticking for another 20-25 years - which I think it's more than capable of.
 

themadman364

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Thanks all for the replies.

AK4FN - thanks for the tip. I wasn't aware that Bill always recommended using an external PS. My PS is based on the LM338 ( a 5-amp version of the LM317 adjustable voltage regulator).

Guys, thanks again. Obviously i'm not a newbie when it comes to electronics, I just want to help make sure that this baby keeps on ticking for another 20-25 years - which I think it's more than capable of.

Both my 2006's lost their internal supplies long long ago. One fell victim to a memory upgrade and it being mounted in a vehicle, and the other to a 232 interface board. Both run off 12V supplies just fine. I also remember Bill saying to never use the internal, as it was too close to other components, built up heat, etc. If you remove the internal transformer, it removes a pound of weight from the scanner as well.
 

KR4BD

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The Pro-2004 was a great scanner. I've had mine since they came out and still use it. Mine is totally originally. The display finally gave out last year. The only thing I've had to do with it is replace the backup battery and spritz the volume control with contact cleaner every year or two. Fortunately, our local PD and Sheriff are still using conventional analog. But, I realize it's days are numbered!
 

af0h

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Thanks again, guys. I just performed a low-voltage experiment and found interesting results.

The PRO-2004 was put on my variable supply and voltage adjusted down until it quit scanning. The low-voltage cut-off operating point was exactly 9.4 volts. This is the point where the screen went blank (still back-lit though). When I increased the voltage back above 9.4 volts, it started up and resumed scanning.

This helps me a lot, since I use battery backup for Ham/SW/Receiving operations when the power goes out, or just decide to run the shack off-grid for the day. My biggest concern was how the PRO-2004 would act on battery power. Since most Deep Cycle Lead-Acid Marine Batteries have their RC and AH ratings calibrated for a cut-off voltage of 10.5 volts, this won't be a problem for the 2004. It seemed to run fine at that voltage, and no lack of sensitivity or volume was noticed.

Now I don't like to run equipment at that low a voltage, since we all know that when voltage decreases - current increases. That being said, I would have no problem running this unit on battery power when the battery does drop below 12.0 volts. I'd probably cut it off myself around 11 to 11.5 volts just to keep from discharging the battery too deeply.
 
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