Re: New member saying Hi.

I don't know how far the part numbers differ from the UBC780XLT and the BC780XLT. The parts may be the same in this case. BC780XLT has a NPN Epitaxial Planar Silicon Transistor in a TO-220ML package. In my BC78XLT the part number is 2SD1667R. When you turn the volume knob and switch the unit from off position to on position you are completing a circuit involving this transistor. The unit is designed so that the center pole (the positive lead) of the power plug is connected to one side of a two pin transformer, the other side (other pin) of this transformer is routed to one side of the On/OFF switch built into the Volume/Squelch control, when the knob is turned to the on position, the switch inside the knob closes and sends the (+) power to various circuits and directly to pin two of J7. J7 connects to a wire harness that connects to a small and simple PCB board that has the 2SD1667R transistor. This transistor is mounted directly to a shelf made in the frame directly behind the area where the VFO/SELECT Knob and VOLUME-SQUELCH knob meet on the front panel. If you unplug your unit, turn it to ON (discharge the stored charge), flip the unit so the speaker now directs upwards, remove the four screws holding the cover containing the speaker, and carefully lift the cover side that runs along the faceplate, you can take a glimpse at the black transistor I am referencing, it will be on your left hand side, just be careful not to lift the cover too high as you could break your internal speaker components. the unit body (the black part) is 16mm X 10mm X 4.5mm and has three legs that protrude 14mm and are 0.75mm X 0.7mm. you will notice that the legs pass through the simple PCB. Connected to that small PCB will be a three wire harness that connects to a three pin connector on the main PCB marked as J7.

The reason you notice the unit warming up when on is because of this transistor. The frame serves as a heat sinking radiator which is why the unit feels warmest directly behind the VFO/SELECT and VOLUME-SQUELCH knobs when the unit is on. This is normal operation, all transistors dissipate energy as heat, similar to how a car engine gets hot when it is running.

Dimming the backlight will only reduce the heat produced by the backlight diodes, and may make it hard to navigate the device. Since the lights are isolated to the front panel, the backlight suggestion will not address the greater source of heat, and it may not be practical.

I do not suggest using any fans as these produce magnetic fields and can impact your scanner. If you can't sleep because the heat concerns you that much, you can go out and salvage some old computer processor heat sink/s (ideally copper, aluminum will work, ideally you can find a copper cored aluminum heat sink) and Artic Silver 5 Thermal compound. Securely and tightly fasten the heat sink/s to the side of the case via bolt and nut (or copper screws which will match the existing case screw thread size and step.)

I think the most basic entry level heat pump solution is best made with an Intel Slot 1 processor Heat sink. This type of heat sink is not too large and suitable for the scanner's design. Just remember, Artic Silver 5 compound and NO use of a fan!
--- In [email protected], "Bigjed" <gerrytweedie@...> wrote:
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> --- In [email protected], "Bigjed"  wrote:
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> > Right,thank you Michael.One other thing,the ProScan software seems pretty good,but I'd like to know how,in other's opinions,it compares to the ARC780.I feel I could get to grips with ProScan OK as I really just want to be able to program the 780 from my keyboard for now.Both are capable of much more I'm sure.
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> > Gerry.
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> > --- In [email protected], michael  wrote:
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> > > Yes, normal.
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> > >Couple more little queries guys,if you din't mind.I noticed that when entering some Mil-Air frequencies that the 780 would tend to 'round them up' to the nearest whole Mhz. EG when I entered 236.175,it appeared as 236.2000 on the scanner.Normal,or a wrong setting somewhere?
> My 780 seems to run kinda warm after a while.Pretty warm in fact.Again normal or not?
> Also it seems from some research on the subject that I may as well forget about Trunking,as there are practically NO users in N.Ireland.A pity,as I was looking forward to trying it out.
> Me and my 780,ProScan,and FlightRadar24 are doing just fine for the moment.I think I will go ahead and buy Proscan.Seems to do everything I need it to do.
> 
> Gerry,Norn Iron.
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