Amprobe resistor identification - Page 1
Forum section: electronics / beginners

author: Captnshacky
author_rank: Newbie
timestamp: May 06, 2019, 11:43:52 am
content: Could someone here help me identify this resistor? If it is even a resistor. Its directly solder to the positive lead trace of an Amprobe ACD -41PQ. I asked Digikey to identify and they say the color bands do not make any sense. Which is the same conclusion I got. Any help would be great. Thanks

author: radiolistener
author_rank: Super Contributor
timestamp: May 06, 2019, 12:01:44 pm
content: according to color code calculator, this is 10.2 Ohm ±3% resistor:https://www.allaboutcircuits.com/tools/resistor-color-code-calculator/

author: Captnshacky
author_rank: Newbie
timestamp: May 06, 2019, 12:05:56 pm
content: Thanks for the help. Would this be a 4 or 5 band color code? Just for my future reference.

author: Captnshacky
author_rank: Newbie
timestamp: May 06, 2019, 12:17:48 pm
content: This is what Digi-Key came up with. They said is was the closets choice.https://www.digikey.com/products/en/resistors/through-hole-resistors/53?k=10.2+OHMS+AXIAL&k=&pkeyword=10.2+OHMS+AXIAL&sv=0&pv2085=u10.2+Ohms&sf=0&FV=ffe00035&quantity=&ColumnSort=0&page=1&stock=1&pageSize=25

author: retiredcaps
author_rank: Super Contributor
timestamp: May 06, 2019, 06:40:51 pm
content: A picture of that resistor and its surrounding area might help us help you?

author: Andy Watson
author_rank: Super Contributor
timestamp: May 06, 2019, 07:05:35 pm
content: 1k 5%.Edit: I think the orange band is a voltage rating - 300V.

author: retiredcaps
author_rank: Super Contributor
timestamp: May 06, 2019, 07:17:29 pm
content: Quote from: Andy Watson on May 06, 2019, 07:05:35 pmThat would be my guess as well if the resistor is part of the input protection. Likely a fusible 1k resistor found in many higher end multimeters.http://mrmodemhead.com/blog/fluke-87-fusible-resistor/@Captnshacky, is that resistor open in your clamp meter?

author: Jwillis
author_rank: Super Contributor
timestamp: May 06, 2019, 09:56:04 pm
content: Although many resistor code charts don't show orange as a tolerance, some do .Orange band is 3% toleranceSo the resistor is a 10.2 Ohm 3% tolerance

author: Andy Watson
author_rank: Super Contributor
timestamp: May 07, 2019, 09:57:31 am
content: Curious! To those advocating 10.2 at 3%, does it not worry you to be specifying three significant digits on a resistor that has 3% tolerence?

author: Zero999
author_rank: Super Contributor
timestamp: May 07, 2019, 02:49:18 pm
content: Quote from: Andy Watson on May 07, 2019, 09:57:31 amI agree. It does sound strange. 10R2 is an E96 value, which is normally only used for 1% tolerance parts or better. I'd expect a 3% tolerance resistor to be an E24 value, with E48 being feasible, but not E96.https://en.wikipedia.org/wiki/E_series_of_preferred_numbers#E24_vs._E48,_E96,_E192

author: Captnshacky
author_rank: Newbie
timestamp: May 07, 2019, 11:06:45 pm
content: Here the entire pcb. Gold band was closet to the lead input or the left side of this pcb. Thanks guys

author: Captnshacky
author_rank: Newbie
timestamp: May 07, 2019, 11:16:18 pm
content: Quote from: retiredcaps on May 06, 2019, 07:17:29 pmYou may be correct. I would hate to send this to Amprobe for repair for a simple resistor swap....

author: Captnshacky
author_rank: Newbie
timestamp: May 07, 2019, 11:44:33 pm
content: Does this look correct? Its a 1k 5%https://www.mouser.com/ProductDetail/Vishay/NFR2500001001JA500?qs=%2Fha2pyFadujwYBQf3%252BFYSuuGxPDNPv1QpIGWG5vyaRjUWSvp39XiAA%3D%3D

author: retiredcaps
author_rank: Super Contributor
timestamp: May 08, 2019, 06:14:42 am
content: Quote from: Captnshacky on May 07, 2019, 11:44:33 pmThe one you linked is 1/3 W. Most fusible resistors in the input protection is 1W or 2W. I suggest this one as per modemhead's bloghttps://www.digikey.com/products/en?keywords=OY102KEAs a test to see if your clamp meter works, and assuming your existing resistor R2C is open (since you didn't answer me earlier), I would just put in a normal 1k resistor to test low voltage measurements like a 1.5V AA cell. If that works, then order the replacement part.

author: Captnshacky
author_rank: Newbie
timestamp: May 08, 2019, 10:37:56 am
content: Quote from: retiredcaps on May 08, 2019, 06:14:42 amWill it matter that its 10% and not 5%? Thanks

author: David Hess
author_rank: Super Contributor
timestamp: May 08, 2019, 08:18:11 pm
content: Quote from: Captnshacky on May 08, 2019, 10:37:56 amNo, it will not matter.I also think it is 1k 5%. It is some sort of flame proof or fusible resistor for safety and overload protection.

author: retiredcaps
author_rank: Super Contributor
timestamp: May 08, 2019, 10:29:24 pm
content: Quote from: Captnshacky on May 08, 2019, 10:37:56 amModemhead's blog that I linked tells you why.http://mrmodemhead.com/blog/fluke-87-fusible-resistor/"The replacement I’ve selected is a 1kΩ 2W Vishay metal-film fusible resistor. It is 5% tolerance instead of the original 1%, but the value of this resistor does not affect the calibration. (It is in series with the voltage divider’s 10 Meg input impedance, which far outweighs any variations in this resistor.)"

author: Captnshacky
author_rank: Newbie
timestamp: May 08, 2019, 10:57:37 pm
content: R2C is open. You assume correct. Thanks for the help

author: retiredcaps
author_rank: Super Contributor
timestamp: May 08, 2019, 11:05:22 pm
content: Since RC2 is open, it's prudent and very quick, qucker for you test, than for me to write this out, PTC, SPG1, SPG2 and SPG3.The PTC should be around 1k ohm. SPG1, 2 and 3 should all measure open circuit.

author: Captnshacky
author_rank: Newbie
timestamp: May 08, 2019, 11:11:57 pm
content: Quote from: retiredcaps on May 08, 2019, 11:05:22 pmall correct 1.7k ohms on PTC Thank you so much for the help.

author: retiredcaps
author_rank: Super Contributor
timestamp: May 09, 2019, 05:08:56 am
content: Quote from: Captnshacky on May 08, 2019, 11:11:57 pm1.7k ohm is in the ball park. I just see Fluke use 1k to 1.1k ohm for their PTCs. I wouldn't worry too much about 1.7k ohms.I found a PTC in the 100k ohm range on one used/abused meter.