BC780XLT: BC780XLT issues after home lightning strike

[bongo1]

My 20 year old 780XLT was the victim of a lightning strike in june..there was a burnt smell so i parked it until now. The antenna(outside unit) was disconnected but the 12volt power cube wasn't. So today i pulled the case covers and did a visual(all looked ok) so i plugged in a 12v supply of a battery and it worked...well sort of. The display is dimmer but viewable kind of like the old dimmer medium setting and the audio is reduced..full volume like what used to be 1/2 volume. My old channel entries along w/ alpha tags stayed put. The audio quality and squelch seem fine to me at this point. In conclusion..just dimmer and less volume..i hate to do a full reset as i would lose all my channels and tags. Any advice would be appreciated.

 

[mancow]

Back it up first with Proscan.

 

[bongo1]

thanks for the option..
Just checked the original uniden wall power supply..reads 19vdc unloaded..

 

[lou9155]

My 20 year old 780XLT was the victim of a lightning strike in june..there was a burnt smell so i parked it until now. The antenna(outside unit) was disconnected but the 12volt power cube wasn't. So today i pulled the case covers and did a visual(all looked ok) so i plugged in a 12v supply of a battery and it worked...well sort of. The display is dimmer but viewable kind of like the old dimmer medium setting and the audio is reduced..full volume like what used to be 1/2 volume. My old channel entries along w/ alpha tags stayed put. The audio quality and squelch seem fine to me at this point. In conclusion..just dimmer and less volume..i hate to do a full reset as i would lose all my channels and tags. Any advice would be appreciated.

is your home ok?..i wonder because i use a non permanent discone setup..just ent pipe in an unbrella stand. but any chance of lightning/thunderstorms i disconnect my coax . i know i really got do the grounding right

 

[bongo1]

Home survived but i lost Wide screen tv,laptop(connected only to its power supply,another scanner in the garage,o guage train TIU computer and more..storm came up quick.State Farm stepped up nicely..seemed kinda of random what got damaged.

 

[w2xq]

is your home ok?..i wonder because i use a non permanent discone setup..just ent pipe in an unbrella stand. but any chance of lightning/thunderstorms i disconnect my coax . i know i really got do the grounding right

Not to sidetrack the scanner problem...

Decades ago lightning struck a 100' pitch pine rooted about 15' from the house's electrical meter and ground. (The lines are underground.) The electrical charge rippled through the house's electrical wiring coming through the ground. The various UPS on computers did their job, but a television power supply went out. Moral? Antenna grounding isn't the only concern to consider when lightning is afoot.

 

[wtp]

from the manual

You must use a power source that supplies 13.8 V DC and delivers at least 700 mA.
check the label on the transformer.
unloaded it would go up a bit.

 

[lou9155]

Not to sidetrack the scanner problem...

Decades ago lightning struck a 100' pitch pine rooted about 15' from the house's electrical meter and ground. (The lines are underground.) The electrical charge rippled through the house's electrical wiring coming through the ground. The various UPS on computers did their job, but a television power supply went out. Moral? Antenna grounding isn't the only concern to consider when lightning is afoot.

hi neighbor!.....thats for sure..luckily we dont get alot of lightning here....i never thought about trees getting hit and then zapping the underground electric feed

 

[bongo1]

Electrician and a fire dept inspector suggested underground strike as well...no visible damage to house..antenna to the scanner was disconnected.My Yaesu FT-DX1200 was disconnected as well. Here is what is weird..the laptop with power connected fried the laptop. New computer arrived and inadvertently i have been using the replacement laptop with that power supply with no issues.
Any way..should i try the uniden scanner cube even though it reads 18.5 to 19vdc unloaded?

 

[kruser]

Electrician and a fire dept inspector suggested underground strike as well...no visible damage to house..antenna to the scanner was disconnected.My Yaesu FT-DX1200 was disconnected as well. Here is what is weird..the laptop with power connected fried the laptop. New computer arrived and inadvertently i have been using the replacement laptop with that power supply with no issues.
Any way..should i try the uniden scanner cube even though it reads 18.5 to 19vdc unloaded?

I'd try it. The wall warts back in those days were not regulated so seeing 19 VDC with no load is not out of the question.
If your backlight and audio volume return to normal, your test adapter may not be putting out the current the 780 needs.

If this does work, it may be a good idea to get a regulated supply that can put out the current the 780 needs. No sense in supplying a higher voltage if not needed. This just makes the internal regulator run hotter as it dissipates the higher voltage.

 

[wtp]

i will try again

what does the wall wart label say about voltage and current ??

 

[bongo1]

Not using a cube . Using a jumper pack cig plug to barrel jack to power the scanner.Lead acid battery in the pack..17ah and reads 12.63.

 

[Ubbe]

Backlight and speaker amp are one of the few things that run directly from voltage from the power supply.
Most of the rest run on lower voltage from voltage stabilizers in the scanner.

I can't see the CPU have anything to do with the two problems. If you can change the backlight between off- middle-high then you can check that the voltage after the on/off switch are ok, it's labeled SWB on the circuit board.

/Ubbe

 

[bongo1]

Why voltage values should be present at SWB? Also the 3 legged regulator or? mounted with a machine screw..what is its function?

 

[kruser]

Why voltage values should be present at SWB? Also the 3 legged regulator or? mounted with a machine screw..what is its function?

Can you read the number on the three terminal device?

I'm thinking it is a regulator. Is that device running hot to touch after the 780 has been powered on for say 10 minutes?
If it's running hot, this could indicate a shorted device on the load or output side plus it could indicate a failed regulator. Measure the voltage between the scanners grounded case and all three terminals on this device and post them here along with any numbers printed on it if you can read them.
If it's a standard device, you can probably google the number and get a pinout so you know which pin in B+ and which is ground and out.

 

[jim202]

What most people miss is that if the home is more than about 10 years old, you may want to take a look at the ground rod under your electrical meter. Take a shovel and dig down around it and see just what shape it's in. They tend to corrode and then the low resistance they are suppose to provide is no longer there.

The reason I bring this up is that I had a tree take a hit near my house. The charge jumped into the tree next to it who had roots coming right up to the slab foundation of my house. The slab was constructed with pre stressed cables in it. Well the charge managed to jump to one of the ends of the cables on the edge of the slab and got into the house. Had all sorts of damage done to electronic items around the house.

Working for a cellular carrier at the time, I borrowed the ground tester and measured my ground rod resistance. Word of caution here. Kill the main breaker of the house before doing this. Then disconnect the ground wire going to the ground rod. It measured about 200 Ohms resistance. Got a new ground rod installed and measured it. It now was down where it should be at about 5 Ohms resistance.

I also suggest that a main electrical panel surge protector be install on your breaker box. This way you have surge protection for the whole house. But the surge protectors need a good ground to function. Poor ground resistance, poor protection. This goes for the surge protectors that you may have right at your devices. If your electrical system doesn't have a good ground, they won't work.

Hope this is some info for thought about your home and protecting the electronic devices you have.

 

[bongo1]

Excellent..i will grab some temp and voltage reads and post as soon as i can..FWI when i first turn on the scanner the display appears brighter for maybe a 1/2 second and then settles to medium brightness.

 

[Ubbe]

SWB is the voltage after the on/off switch, which should be the same as the power supplys voltage.

The three legged component are the 9V regulator that powers most of the scanner. If that's gone bad then the scanner shouldn't work normal. It should be printed 9v on the circuit board that can be measured. If you measure on the regulator and slip only the slightest you could destroy the regulator and it could also send the power supply voltage to all circuits that are designed for 9v.

/Ubbe

 

[bongo1]

Thanks..i have test probes and shall proceed with caution.Just did the finger on reg test..not even warm.

 

[bongo1]

Looking at the reg philips screw front..left leg 5.47 ctr 5.9 right leg 4.75 vdc
Regulator numbers are
D1667
R 0J5...i think really hard to see.
also not finding "SWB"..there is an 8 pin con at the on/off sw.