EEVblog Electronics Community Forum

Electronics => Repair => Topic started by: montarbo on March 17, 2019, 08:24:18 pm

Title: F27 resistor value
Post by: montarbo on March 17, 2019, 08:24:18 pm

Hello,
Thanks a head for help with SMD resistor value. A code F27 on the resistor itself.

Title: Re: F27 resistor value
Post by: shakalnokturn on March 18, 2019, 08:10:48 am

Size, circuit context  and maybe a photo would be helpful.
Any way it could be a fuse?

Title: Re: F27 resistor value
Post by: montarbo on March 18, 2019, 11:41:06 am

1812 package and its in PSU mains input to an industrial LED light, there are two of these in series with a TH (green, black, silver, gold, blue), ie
F27--TH as above--F27. Both the F27 are fried. 

Title: Re: F27 resistor value
Post by: montarbo on March 20, 2019, 07:35:45 pm

Any ideas???

Title: Re: F27 resistor value
Post by: shakalnokturn on March 21, 2019, 06:28:58 pm

Check if there is a fuse anywhere else.
Is TH a NTC thermistor? What power is the light?

With no better clues I'd throw in a couple of 27 \$\Omega\$ fusible resistors.

Title: Re: F27 resistor value
Post by: SiliconWizard on March 21, 2019, 08:28:16 pm

If this is indeed a resistor, this should be a 12Mohm, +/-5% resistor.

See here for SMD resistor marking:
http://www.marsport.org.uk/smd/res.htm (http://www.marsport.org.uk/smd/res.htm)

Title: Re: F27 resistor value
Post by: shakalnokturn on March 21, 2019, 11:52:21 pm

12M \$\Omega\$ on the power input that's not going to fit...

Maybe TH is trough-hole, in that case the TH would be an inductor.
An inductor and series resistor is a common setup on the input of cheap SMPSs. I'd still stick to 2x 27 \$\Omega\$ but check power consumption and size of bulk capacitor.