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First of all it is called a diode and it is an active component. The way you test it is , first remove power from the circuit, then using a ohm meter on the high power ohms or diode test function. It should read high resistance in one direction and low resistance in the other direction you also can use a battery and light bulb in series connected to the diode. The light should light in one direction and not the other. If the diode is across a coil or low resistance device it may not be able to be tested accurately in circuit, in this case one end will need to be lifted from the circuit to test.
The resistor is acting as a fuse and will continue to blow until you fix the REAL problem. LIKELY the filter capacitor(s) beyond the bridge rectifier are failing. One needs to use test equipment to measure the current through the resistor and see if it is reasonable. The capacitors can heal briefly and then start to short. One should also check the rectifier in operation with an oscilloscope as one diode could intermittently short.
Is the pwr supply the one that blew. if so that is a fullwave bridge rectifier. around 40-45amps that is what makes the AC wall volts from transformer into the 28volts DC to run the power transistors in the rear on the heatsink.
Check the power supply transformer primary driver transistor and the associated components (some diodes and capacitors, resistors, an optocoupler maybe) and the rectifier diodes (or a bridge) and capacitors at the transformer secondary, what you are looking for is a short circuit, however, the short may as well be in another section of the circuit board (a shorted component may sometimes have signs of damage caused by heat, but this is not a rule).
pulling to many amps,diodes could not handle amps so they failed.unit should have kicked its breaker before the diodes burned out.most units have their own breaker to protect the system.I would replace the control board first see how unit reacts,probly fine,if not the you go to next step.
check your power board not the inverter board. Caps, diodes usually go first. get them replaced with a higher voltage capacitor, same value (1000 uF 15v with a 1000 25- 35v is ok)
You badly need a service manual, you might be able to get one at the Thermal Arc home page. Since it blew the input power breaker and let off a bit of smoke we'll take as given that something in there shorted. Inverter welders like this have a rectifier section, then an inverter section, then another rectifier section before the torch. I'd bet a little money that what went pop was one or more of the SCRs in the rectifier section. You really need the manual to do anything useful to this machine, pay particular attention to the repair sections where they talk about cold checks before powering the machine on again, it'll save you hours of replacing parts.
OK. I do not know the exact number for the diode off hand, because I don't have the same radio in front of me. On most cb radios, this diode is usually located on the component side of the pc board, close to where the positive lead solders to the board. Most of the time when it burns, it just becomes brittle.
If you do replace it on your own. The diode is called a rectifier diode, which you can pick up at radio shack or at partsexpress.com. The part number is between 1N4001 to 1N4008. When installing be sure to observe polarity, making sure that the side with the silver band is facing the direction of the arrow.
If I can help anymore, please don't hesitate to ask.
blown resistor (42ohm) replaced this and it imediately blew
it clearly shows that there is a short circuit in your tv.
if you are a tech person please proceed as follows.
1 isolate power supply from hor.output section.
2 now check power supply section.i.e. switching tran., cap..diode etc.
3 if it becomes ok check power supply output.
4 if output is ok then check hor. output section.i.e. h.out tr.,cap& diode in eht winding.
5 check print near eht.
6 at finally eht.
7 see every thing is normal now.
now reconnect power to hor.section.
put on tv.
good luck.
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