Resistor that looks like a capacitor - Page 1
Forum section: electronics / repair

author: zz28zz
author_rank: Regular Contributor
timestamp: November 28, 2019, 12:33:20 am
content: Found a couple of capacitors on an old car stereo amplifier that measure as open and need to be replaced. They look like 1/8 watt resistors and have bands like a resistor.They have the following sequence of color bands:Brown-Green-Black-Gold-BlackI'm pretty sure that means 15p 5% but not sure abt the last black band.Found a couple of color band maps online. The last band has to do with voltage but seems to depend what type of cap it is. Ceramic is not listed as an option. Can I assume 100V?

author: floobydust
author_rank: Super Contributor
timestamp: November 28, 2019, 12:41:19 am
content: can you post pics?

author: zz28zz
author_rank: Regular Contributor
timestamp: November 28, 2019, 02:05:41 am
content: Here's a pic of one. Cap is pretty small. DIP included for scale.

author: coppercone2
author_rank: Super Contributor
timestamp: November 28, 2019, 02:15:10 am
content: I think they are called bumble bee capacitors

author: andy3055
author_rank: Super Contributor
timestamp: November 28, 2019, 02:21:44 am
content: Since it is from a car radio/amp. you will be safe to use anything with 50v rating which is easily found.

author: zz28zz
author_rank: Regular Contributor
timestamp: November 28, 2019, 03:12:26 am
content: Digikey has two 100V options but no 50V in stock. Guess I'll be going with a 100V.

author: andy3055
author_rank: Super Contributor
timestamp: November 28, 2019, 05:58:21 am
content: Quote from: zz28zz on November 28, 2019, 03:12:26 amhttps://www.mouser.com/ProductDetail/Murata-Electronics/RCE5C1H150J0K1H03B?qs=sGAEpiMZZMuMW9TJLBQkXnz0ht4ERydtJwj1BZh32ok%3D

author: zz28zz
author_rank: Regular Contributor
timestamp: November 28, 2019, 06:47:55 am
content: Is there any advantage to using a 50V as opposed to a 100V?One of the 100V caps was low ESL. Any advantage to using low ESL caps at audio frequencies?

author: andy3055
author_rank: Super Contributor
timestamp: November 28, 2019, 06:58:37 pm
content: Quote from: zz28zz on November 28, 2019, 06:47:55 am50v/100v is the working voltage. The higher the safer, but you don't need it to be so much in a low voltage circuit like this and the higher rated might be too large physically. As for ESL, I am not sure how the effect will be. I usually prefer caps that have low to no leakage.

author: m3vuv
author_rank: Super Contributor
timestamp: November 29, 2019, 09:24:11 am
content: that looks more like a choke to me?

author: gbaddeley
author_rank: Regular Contributor
timestamp: November 29, 2019, 09:58:09 am
content: Yeah, me too. OP, where is it located in the circuit? Does it join two voltage rails, or is across rail to 0 V?

author: coromonadalix
author_rank: Super Contributor
timestamp: November 29, 2019, 11:22:21 am
content: I would have said the same thing, they are inductors not resistors.Show us photos where they go on the pcb ?? pcb markings ...

author: zz28zz
author_rank: Regular Contributor
timestamp: November 29, 2019, 07:31:38 pm
content: Components in question are C559 and C560. I made rectangular outlines around them on the enclosed schematic. (The circled components were the ones I found to be overheated when I first started repair)The cap is sorta across the +/- 50V rails but not directly. See attached.I'm not 100% sure they are open. Their advertised capacitance is below the lower limit of my cap meter. If I connect the two 15P caps in parallel then attach cap meter, it still reads open but I'm still right at the lower threshold of my cap meter.