Help identifying a five bands resistor from a Canberra 2022 - Page 1
Forum section: electronics / beginners

author: Erik L
author_rank: Contributor
timestamp: June 02, 2024, 10:57:48 am
content: I had an issue with a NIM Canberra 2022 amplifier I recently purchased. The "holly smoke" started pouring out after I inserted it into my BIN and powered up the unit. After shutting down, removing, and opening the amplifier, I found that the current limiting resistors were burnt out, likely due to some defective tantalum capacitors. I identified at least three capacitors as shorted.I am now trying to identify the resistors with the following color bands: wide silver, brown, black, black, and silver. The size of the resistors is approximately 2 mm by 6 mm. Typically, the color code ends with two silver bands.Can you help me determine if these resistors are 100 Ohm or 1 Ohm 1/4 W or something else?Thanks for your help!

author: wraper
author_rank: Unknown
timestamp: June 02, 2024, 11:11:36 am
content: You literally have 8 of the same resistors, just measure them.

author: Erik L
author_rank: Contributor
timestamp: June 02, 2024, 11:13:14 am
content: They are fried, no consistency in the measured values.

author: pcprogrammer
author_rank: Super Contributor
timestamp: June 02, 2024, 11:26:09 am
content: Quote from: wraper on June 02, 2024, 11:11:36 amThat is what I would do.But as silver at both ends of the resistor is not normal, my guess is that you have to ignore the wider band and then it would be 100 Ohm 10%. To validate this you can also see what the supply voltage is and consider if the damage concurs with what you see. At 5V there is enough current to heat up a 100 Ohm 1/4W resistor, but would take a while to burn up. At 20V it is consuming 4W and can go up in smoke more easily. For 1 Ohm it would be 25W at 5V and that for sure would smoke it up real good.

author: Andy Watson
author_rank: Super Contributor
timestamp: June 02, 2024, 11:41:44 am
content: Are there any legends on the pcb to indicate the component type? The sivler at boths ends, and the style of case makes me think that these are inductors (100\$\mu\$H10\$\mu\$H).The manuals for Canberra suggest that you can contact them for circuit diagrams - and other technical help. It might be worth contacting these people (who now own Canberra):https://www.mirion.com/mirion-technologies-canbera-bnls-nv

author: wraper
author_rank: Unknown
timestamp: June 02, 2024, 12:14:22 pm
content: Quote from: Erik L on June 02, 2024, 11:13:14 amYou don't need consistency. You need one with lowest value and that looks like it could match the rings.

author: Erik L
author_rank: Contributor
timestamp: June 02, 2024, 06:03:34 pm
content: This topic can be closed.The second ring wasn't brown but rather orange...Silver: ~10 %Orange: 3Black: 0Black: 0Silver: x 0.01The resistor value is 3 Ohm 10 % 300x0.01=3Thank for your help!

author: daisizhou
author_rank: Super Contributor
timestamp: June 02, 2024, 10:40:13 pm
content: This resistor looks like a carbon core resistor, but it is not easy to buy it.

author: wraper
author_rank: Unknown
timestamp: June 02, 2024, 10:56:26 pm
content: Quote from: daisizhou on June 02, 2024, 10:40:13 pmAnd you shouldn't as they're garbage.

author: Andy Watson
author_rank: Super Contributor
timestamp: June 03, 2024, 06:54:46 pm
content: Orange ! My eyesight might be fading but orange?Something I suspected but only found out for sure today: The doulbe-thick silver starting band indicates an indicutor, specifically one with "mil-spec" marking. So they are 10\$\mu\$H inductors 10% tolerance. (Or 30\$\mu\$H, if you insist on orange)

author: wraper
author_rank: Unknown
timestamp: June 03, 2024, 07:43:09 pm
content: ^I never seen inductors of this package style but found some while googling. Also I found about silver band being military identifier, although not sure if it's inductor exclusive. Band is brown on the picture, however considering there are signs of overheating paint could have changed the color. Also considering these look like carbon composition resistorshttps://www.ebay.com/itm/144613216641, those that did not fail entirely could have drifted to high side a lot, they're notorious for this. In any case I think it's worth to check their inductance or break one apart to see what's inside.

author: daisizhou
author_rank: Super Contributor
timestamp: June 03, 2024, 08:03:12 pm
content: Quote from: wraper on June 03, 2024, 07:43:09 pmCarbon composite inductors or carbon core inductorsOK .My wrong perception

author: wraper
author_rank: Unknown
timestamp: June 03, 2024, 08:44:55 pm
content: Quote from: daisizhou on June 03, 2024, 08:03:12 pmMakes no sense, who the hell would put carbon core into inductor. Not to say supposed 10uH inductance won't be possible with non ferromagnetic core.

author: floobydust
author_rank: Super Contributor
timestamp: June 03, 2024, 09:18:03 pm
content: OP, I recognize the components as Dale (Vishay) inductors, the IM series.

author: jmelson
author_rank: Super Contributor
timestamp: June 04, 2024, 01:59:30 am
content: Those are inductors, for power supply filtering.Jon

author: Erik L
author_rank: Contributor
timestamp: September 02, 2024, 04:27:09 pm
content: Thank you very much for your help.Yes, those are indeed inductors.I ordered new ones, as well as tantalum capacitors for the power rails.Unfortunately, this didn't solve the issue.When I re-powered the device after fitting the new components, the "holy smoke" returned...