Resistor Identification - Help Needed - Page 1
Forum section: electronics / beginners

author: Melkor
author_rank: Contributor
timestamp: March 30, 2014, 12:49:04 pm
content: Hi,It's about a 2-3W resistor based on it's size(about 15x5mm).However I'm not sure about the value of the attached resistor.Could a more experienced person help me with the value and the reasons behind it ?Thank You.

author: Fank1
author_rank: Regular Contributor
timestamp: March 30, 2014, 12:57:34 pm
content: Looks like .12 ohms 5%

author: dentaku
author_rank: Frequent Contributor
timestamp: March 30, 2014, 01:05:36 pm
content: Quote from: Fank1 on March 30, 2014, 12:57:34 pmBrown-Red-Silver-Gold would be 0.12 ±5% but what's the Green stripe?

author: Dave Turner
author_rank: Frequent Contributor
timestamp: March 30, 2014, 01:13:31 pm
content: I read it as 12.8 Ohm at 5%5 band colour codeBrown 1Red 2Silver 8Gold 0.1 multiplierGreen +- 5% tolerance

author: romantronixlab
author_rank: Regular Contributor
timestamp: March 30, 2014, 01:21:28 pm
content: Quote from: Dave Turner on March 30, 2014, 01:13:31 pmExactly what i was going to write. But instead of 5% tolerance according to my table from a EE E-book green would be .5% tolerance

author: grumpydoc
author_rank: Super Contributor
timestamp: March 30, 2014, 01:27:02 pm
content: QuoteOK, but that precision at that tolerance doesn't make sense.Not to mention that not even E192 has 12.8 - 12.7 and 12.9 would be closest

author: romantronixlab
author_rank: Regular Contributor
timestamp: March 30, 2014, 01:29:51 pm
content: Quote from: grumpydoc on March 30, 2014, 01:27:02 pmWas thinking the same thing. Could have been a defect in the banding?

author: grumpydoc
author_rank: Super Contributor
timestamp: March 30, 2014, 01:33:55 pm
content: What does it currently measure?

author: Melkor
author_rank: Contributor
timestamp: March 30, 2014, 01:36:33 pm
content: I should add that the resistor is from a faulty PC power supply(Fortron FSP400-60APN, no schematics).It measures about 0.12Ohm on a Tonghui TH2822A.So, do you think is a good 0.12Ohm resistor with some strange banding or a shorted larger resistor ?

author: grumpydoc
author_rank: Super Contributor
timestamp: March 30, 2014, 02:12:20 pm
content: QuoteIt's more common to find a resistor has drifted up in value rather than down so I'd suspect it is meant to be 0.12ohms.

author: SeanB
author_rank: Super Contributor
timestamp: March 30, 2014, 02:27:50 pm
content: 0.12 Ohm, 5% fusible resistor. If it measures that then it is working, as they always fail higher value to open circuit. Resistors that are coated very rarely ( almost never and only those that are wire wound) fail by going low resistance, the coating tends to thin or the wire corrodes to make the resistance higher, never lower. The power devices associated with it are open circuit or dead short, probably along with the mains bridge and the fuse which will be open. If the supply is not running check for the standby 5V, it has to be there to get any thing out of the supply. Likely the little 8 pin standby power supply chip is very dead, or the small capacitors associated with it. Check the secondary side of the 5V SBY as well for bad capacitors and shorted diodes as well. Check as well the active PFC on the little heatshrunk board is working to generate about 300-400v on the main capacitor ( use care as any fault here will make it go bang)

author: Dave Turner
author_rank: Frequent Contributor
timestamp: March 31, 2014, 11:22:37 pm
content: Agreed - typo - missed the '0.' from my post. Should have read +- 0.5%However if this is not a standard resistor then all bets are off. Perhaps Melkor could post a reading of the resistance of the component.