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Re: Resistor "calculator"
It's incorrect, though.
I've used 1/4W 0805 and 1/2W 1206 on my boards.
I've also encountered 3W 2512 devices -- as metal hybrid current shunts.Last edited by tom66; 01-14-2013, 03:19 PM.Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
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Re: Resistor "calculator"
"An engineer can do for a dollar what any fool can do for two." - Arthur M. Wellington
I always over-rate my resistors when making my designs. Typically I apply a fudge factor of between 30% and 100%, depending on the customer's requirements and the required cost of the board. (Also, I like to make my circuits more understandable at a glance, so I'll strive to make current shunt resistors bigger, even if that isn't necessary, etc.)
However it is incorrect to say that they can only handle 1/4W (or whatever) at room temperature.
The vast majority are rated up to 70°C or 85°C at full power dissipation.
I have no problem with finding innovative and clever ways of saving money in making electronics, though often it goes too far and we see unreliable electronics.
If an engineer can design something that is half the price but only last 15 years instead of 20 years, I have no problem with that.
If an engineer can design something that is $5 less but only lasts 3 years instead of 15 years, then I have a problem.Attached FilesPlease do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
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Hi
I am trying to repair an ancient Dell 2209WA Monitor which suddenly shut off with a pop sound. On investigation found that one of the fusible resistors had blown. Further investigation identified multiple components as faulty because of which the fusible resistor blew. Please refer the attached circuit diagram showing the components that were found to be damaged.
1. FR950 - blown fusible resistor - 0.2 Ohm 1W
2. Q950 - shorted Q950 MOSFET - 650V 10A N Channel Mosfet
3. R835 - Blown Resistor - 20KOhm SMD resistor
4. D930 - Shorted Schottkey Diode... -
Hi to all forum members,
Got this faulty 350 watt atx psu dirt cheap from a local online seller as i am keen to use it as a learning tool to repair faulty power supply.
The faulty part is quite obvious from the burn area near the 16pin KA7500 BD pwm. The fuse is still intact with good continuity.
Upon power on ac, there is 5vdc standby power on cathode of diode D14 and about 10vdc on cathode of diode D13.(This should be the aux power to generate the 12v and 5v rail.)
Initially i replace the two burned resistors near my marked red arrow to 200 ohm resistor... -
I am curious if a 0402 resistor could go from 43 ohm to 0. In electronics class and my experience a resistor can degrade and gain resistance all the way up to not being able to conduct at all. I have never heard of a resistor decreasing in resistance and becoming 0 ohm or a dead short… that's not the direction they fail… or so I thought.
I was attempting to remove a wson8 chip on an iMac motherboard and it required a lot of heat, on one side of the chip were 3 0402 resistors that were very close. I popped the chip out unintentionally out of the tweezers and sent those resistors... -
The resistor on this waterpik blew. I changed it with the a similar spec 47ohm 2 watt yageo resistor but it still keeps blowing the resistor. Checking with the multimeter the motor, capacitor, diodes, and thermal fuse all checked normal. Will a higher ohm resistor work better? What ohm resistor will work better to repair this waterpik? This video is showing the repair with a 56 ohm resistor https://www.youtube.com/watch?v=_J7_rV7ui1Y -
I have purchased an 100-240v AC/5v 2a DC adaptor from aliexpress,and a month ago It smelled burning when I plugin it powerstrip.
Since then, This AC/DC adaptor have been out of order.
But A few days ago,I replace 0.5 watt resistor with 1 watt resistor(1ohm) in this adapter.
After replacing resistor,It succeed to recharge all of android phone.And When I measure voltage on the two pins of USB port,It shows 5.5v
Is it okay to replace 1/2 watt resistor with 1 watt resistor in AC/DC adapter?
And Is there any possibility that it will suddenly explode as well as to be out...
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