# Repair of a Phillips power board. (help with resistors)

#### Techbox

Joined Aug 15, 2018
8
Hi-
Rather than throw away a Phillips power board I would like to attempt to repair it. This board is known for bad resistors and I am trying to measure them with my Fluke. But first I need to know what they should measure. Problem is these resistors don't exactly fit the pattern shown online. Instead of 3 stripes close together and one separate stripe, 2 of the 3 resistors I am looking at are evenly striped.The third has a separate stripe, but no matter what online calculator I run it through it won't give me the ohms it should be. Here is what I have, I can post pictures but we'll start with this.These are all 4 band. The one with the separated stripe has brown, black , green, and a separate yellow. The next one, evenly striped is yellow, violet, red , silver. The next one is black, gold, red, red. These are the 3 that are in a common area of failure on this board but I would like to learn to measure all. The board is a Phillips PLCD190P5
Thanks for any help!

#### MrChips

Joined Oct 2, 2009
26,099
Welcome to AAC!

A picture is worth a thousand words.
Post pictures.

#### Techbox

Joined Aug 15, 2018
8
The three I am focused on at the moment. If it double posted I apologize, I am new to your system.

#### MrChips

Joined Oct 2, 2009
26,099
R002 - brown black green yellow = 1MΩ ±5% 1W
R015 - yellow violet brown silver = 470Ω ±10% 1W
L009 - red red gold black = 2.2μH ±20% inductor

#### Techbox

Joined Aug 15, 2018
8
R002 - brown black green yellow = 1MΩ ±5% 1W
R015 - yellow violet brown silver = 470Ω ±10% 1W
L009 - red red gold black = 2.2μH ±20% inductor
Humor my ignorance and slow learning R002 should read 1 on my fluke, correct? R015 I had right I believe at 47 1 watt, L009 you lost me.
Thank you for your patience. I assume you are using a chart and not using a calculator that lets you implement stripe color. I had tried to use your which eventually led me to your forum. https://www.allaboutcircuits.com/tools/resistor-color-code-calculator/

#### LesJones

Joined Jan 8, 2017
3,707
R002 should read 1MΩ If it is reading 1Ω then I think you are misreading your meter or there something in parallel with it causing a false reading. If this is so lift one end of the resistor you should get a correct reading.
You did not have R015 right. If MrChips has the multiplier right as being brown then it is 470 Ω On my monitor the multiplier band looks more red than brown which would make it 4.7K Ω
L009 is an inductor not a resistor.

Les.

#### MrChips

Joined Oct 2, 2009
26,099
Humor my ignorance and slow learning R002 should read 1 on my fluke, correct? R015 I had right I believe at 47 1 watt, L009 you lost me.
Thank you for your patience. I assume you are using a chart and not using a calculator that lets you implement stripe color. I had tried to use your which eventually led me to your forum. https://www.allaboutcircuits.com/tools/resistor-color-code-calculator/
Nope. i can read it off the top of my head. After a few months of reading resistor colour codes it sticks in your head like hearing morse code.
brown-black-green is 1M
yellow-violet- brown is 470

#### Techbox

Joined Aug 15, 2018
8
Nope. i can read it off the top of my head. After a few months of reading resistor colour codes it sticks in your head like hearing morse code.
brown-black-green is 1M
yellow-violet- brown is 470
I obviously have a long way to go...I realize measuring in circuit can produce a false reading. But I started there before I tried pulling a leg.
The commonly failed resistor on this board is R015 it reads 490.1 in circuit. The R002 is reading OL in circuit which could be false, so I think I will start there. I missed the L on the inductor but as I said I am learning. I have been repairing computers for 20 years but have mostly just replaced capacitors. Thank you.

#### JoeJester

Joined Apr 26, 2005
4,390
What do you have the meter set for when you read OL on the 1M resistor?

#### Techbox

Joined Aug 15, 2018
8
What do you have the meter set for when you read OL on the 1M resistor?
I have a Fluke that auto ranges.

#### LesJones

Joined Jan 8, 2017
3,707
Are you sure that you have not turned the auto range function off ? What it the model number of your meter ? I am wondering if it is a model designed for a special application (Possibly working on cars.) that does not have a high resistance range.

Les.

#### MrChips

Joined Oct 2, 2009
26,099

#### Techbox

Joined Aug 15, 2018
8

#### MrChips

Joined Oct 2, 2009
26,099

#### JoeJester

Joined Apr 26, 2005
4,390
That explains the OL.

#### ebp

Joined Feb 8, 2018
2,332
This looks like a fairly elaborate eletromagnetic interference/radio frequency interference (EMI/RFI) filter using two common mode chokes.

The 1M resistor is probably just a discharge resistor for the filter capacitors. Its purpose is to rapidly discharge the small filter capacitors when the line cord is unplugged so you don't get a shock if you touch the blades of the plug. It is very unlikely to have failed.

The functions of the 470 ohm resistor and the small inductor are harder to guess without knowing more about the circuit. It would be helpful to have a photo of the back of the board that shows what they are connected to. I'm guessing the resistor is a carbon composition type, which probably means it gets a transient overload (carbon comp handle this better than many other types; for most applications they are very rarely used anymore). It is also ±10% tolerance, which is also now quite a rarity. 490 ohms is well within tolerance.

A photo of more of the area around those parts would also be helpful.

---
I have never encountered a meter with a maximum resistance range of 60k! I presume it is intended for "electrical" work.

#### bertus

Joined Apr 5, 2008
21,896
Hello,

@ebp , It is strange but true. The Fluke113 has 3 Ohm ranges, the max is 60kΩ:

Bertus

#### Techbox

Joined Aug 15, 2018
8
I do have a secondary meter with the capability to set manual range from 200k to 20M I havn't used it yet but will drag it out Monday

#### Techbox

Joined Aug 15, 2018
8
But, since I am a bit of a newbie to circuits and components, explain this to be. If my fluke can only measure 60kΩ then why was it capable of measuring the 490 on the resistor. Or, was that 490 a lesser value than 60? Patience, I am learning = )

#### ebp

Joined Feb 8, 2018
2,332
490 is just that - four hundred an ninety ohms. 60k is sixty thousand ohms ("k" means "kilo"). The meter auto-ranges to select the best range for the value, but the maximum value it can measure is 60k, so any resistor greater than that it just "thinks" is open circuit.

You will find tables of commonly used multiplier suffixes on the web.
Since you are just learning, I strongly recommend learning the "right" way in conformance with SI ("The International System of Units, universally abbreviated SI (from the French Le Système International d’Unités)",)

This document is very useful:
https://www.nist.gov/document/special-publication-330

Unfortunately, you will find lots of non-conformance in electronics, especially things like time in seconds written with a capital S which is wrong
10 mS means ten milli-Siemens (electrical conductance) whereas 10 ms means ten milliseconds