Question about Radio Shack TRC-447 CB Radio

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No power what is the number for protection diode on back of circuit board?

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  • Dean Pitts
    Dean Pitts May 11, 2010

    Lol, I didn't read enough on the tags. I just looked at the description, used to people putting it in there. I will try to find it for u.



    Dean

  • Dean Pitts
    Dean Pitts May 11, 2010

    What brand and model of radio do you have? The item number varies by radio.



    Dean

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It it blowing fuses?

Posted on Nov 05, 2008

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Posted on Jan 02, 2017

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Hi. My uhf band cp 200 won't power up because it was placed in a charger .Please tell me what protection diodes I need to replace, and it's proximal location. Thank You.


Chargers have higher voltage ratings than the one it charges. It also lacks the needed filters to supply the exact direct current which damaged your equipment but first check if it blows up your fuses when you connect the power supply. If it does check for Zener Diodes usually connected to the mains of the equipment to simulate the simple crowbar effect of protection. If it does not blow up your main fuse then the fuse might be in the circuit board of your base unit. Zener Diodes are cased in striped crystal that short circuits itself when applied with reverse or higher voltage rating power supplies. You will need a multimeter positioned at continuity to test this. Remove it and replace the fuse then apply power, it will light up but remember to replace the damaged part for protection.

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Would like a circuit diagram for dell inspiron 1000 power circuit


There is a reverse polarity diode that prob popped. It doesn't allow the power to even reach the battery anymore. It'll prob charge in another laptop that takes that battery. The diode is on the mother board.

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1 Answer

Crossed power wires on uniden c b radio


Remove the top, the red wire is + and the black - there should be a small black diode near by, if the wires were crossed the diode is shorted and must be replaced "part of the protection circuitry" check for any open foils on the circuit board, If you are very lucky the unit will come back online.

Mar 07, 2012 | Uniden Bearcat Pro PC78LTW 40-Channels...

1 Answer

Control board replacement


You may want to look at the following components on the circuit board and replace them as necessary. If there appears to be no power to the machine (clock), the machine may have received a power spike from an unclean/fluctuating power source. Look at resistor R5. If it shows any signs of heat damage, replace it. Then look at diode D3, which has been the cause of malfunction on my unit for four times already. Replace this diode (10V, 1.3W) and it should run again. This diode is working like an over-voltage protection fuse (which should have been built into this machine with easy access in the first place!) and since it gets fried so often on my unit I'm planning an illustrated writeup on how to mod the board to make exchanging this diode easier and without disassembling the machine.

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1 Answer

My tv has double images and color is off, how do i fix this?


If it is a 46GW947 there is a common problem---pretty easy to fix

This model with the set unplugged and the back removed has above all the main boards another board suspended over 12 inches from the main boards--it is about 10 inches wide and 4 inches deep---a few plugs, and 4 screws and it comes right out--among other things it is the main power for the CONVERGENCE circuit in this model.

Towards the far right side of the board you will see several diodes-------two of them near each other are much larger----Commonly on this model one of the two SHORTS, stopping voltage to the convergence circuit.

You can test the diode in this case like checking a fuse----it should NOT have a reading like a fuse--if you find either of those two diodes reads across--it is bad and most likely your problem.

Each diode will have a LOCATION number under it on the top of the board----if you find one bad--let me know the location number and I will get you a part number---both those diodes are somewhat special.

If this has helped you, rate this solution as I do this here for free.

SD TECH

Nov 08, 2009 | GE 46GW947 46" Rear Projection Television

1 Answer

DIODE PART NUMBER 907 ON POWER SUPPLY CIRCUIT HAS HOW MANY VOLTAGES


That diode part number is not recognizable. IT IS possible that the full number is 1s1907.which is a 400PIV diode.

If the diode is about 3/8 inch long and 1/8 diameter replace with a 1N4007 which should have adequate voltage margin if it is a rectifier diode.

One has to be careful as the original could also be a Zener regulator. The board nomenclature for that would likely have "ZD" followed by a number. Verify the diode is used as a rectifier type by tracing the circuit enough.

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3 Answers

Tv turns off a second after I turn it on


Just repaired this actual model.
remove the back of the tv. Loof at the circuit board on the left as you face the back of the tv. In the middle there is a diode that burns out. Remove all ov the screws holding this circuit board to the tv. Carefully unplug all of the connections and flip the board over. See that the number on the back side of the board by the burnt diode is d1940. Have the diode replaced by a competent repairman and oberve polarity. put everthing back as you found it and try the tv. You may want to have a fire extiguisher nearby.

Sep 28, 2009 | Emerson LC320EM9 32 in. LCD HDTV

1 Answer

No power to radio wont even turn on


The most likely thing is what we techs call revers polarity. this means that the customer accedently hook up the power in reverse. this happens more often then not. The fix for this is to replace the 1 amp diode that goes between the negative and positive power input on the board. the Diode number is a 1N4007 or any 1amp silicone diode. You will also see that once Blown diode is cut the radio will come back on. this does not mean the radio is fixed what this means is that the shorted diode has been removed from the circuit. which also means the radio has nom protection until the diode is replaced.

Patrick Patterson N5SLI

Jun 01, 2009 | Cobra 29 WX NW ST 40-Channels Base CB...

1 Answer

Magnum delta force


What you saw smoke was the protection diode. I do not have one of these radios and have not worked on one yet, but most radios are the same where the protection diode is located on the pc board, one the components side, close to where the wire from the main power positive pin is soldered into the pc board.

I will have to do a little research to see if I can come up with the number of the diode. I have a couple of diagrams and a schematic from cbtricks.com. If I can not located it from their informaiton, I can contact my supplier Monday to see if he can tell me the number. If you happen to located the burnt diode before I come up with the information, please respond so I will know.

Dean Pitts
Rollin CBs

Nov 01, 2008 | Radio Communications

2 Answers

Power was reversed now radio keeps bowing fuse and will not come on


Hello hubcap,

 

When the power was reversed this shorted out one of the components, possibly an Operational Amplifier. This tells me that there is no diode protection and possibly the circuitry is exposed directly to the input power supply. The fix would be to find the shorted component with the use of a schematic and a multimeter. Once you correct the shorted component then if possible you can add diode protection by putting a diode (forward biased direction) in the path of the positive line.

 

Again you will need a schematic, and a multimeter to work on this problem.

 

I hope this helps,

 

Thank you,

 

Shuttle83

Oct 12, 2007 | Uniden PC78ELITE 40-Channels Base CB Radio

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